Arsenic Adsorption Technology- A Review of Long-Term

Transcripción

Abstract Volume
Congress
Mexico-City, 20 - 24 June 2006
Editors
Jochen Bundschuh
María Aurora Armienta
(Germany/Argentina/Costa Rica)
(Mexico)
Prosun Bhattacharya
Jörg Matschullat
(Sweden)
(Germany)
Peter Birkle
Ramiro Rodríguez
(Mexico)
(Mexico)
International Society of
Groundwater for Sustainable Development
1
Welcome to the
International Congress
“Natural Arsenic
in Groundwaters
of Latin America”
Dear Participant,
On behalf of the whole organisational team, we
welcome you heartily to this congress which
tands in the tradition of the San Diego conferences and the conference held in Santiago de
Chile – all dedicated to a better understanding
of arsenic-related problems and challenges.
At the same time, we welcome you to MexicoCity, and we hope that you will enjoy both the
enlightening atmosphere of the congress and the
relentless dynamics of this fascinating capital.
The Congress
In many parts of the world groundwater resources – a backbone for human development – naturally contain elevated levels of arsenic (As).
These As-concentrations often exceed the World
Health Organisation (WHO) guideline value of
10 µg L-1. Severe health effects have been associated with elevated As-concentrations in
groundwater used for drinking purposes. Many
people in low income countries, particularly in
South East Asia and Latin America, are most
severely affected. There is increasing evidence of
various susceptibility factors, e.g., malnutrition.
Arsenic in groundwater poses one of the most
important environmental health risks of the
present century. Several million people depending on arsenic-containing groundwater for
drinking purposes are at increased risk of arsenic-related health effects. So far, most research
focussed on As-related cancer effects. More
information about other health effects is needed
and on susceptibility.
During the last decade, As-rich groundwaters in
South and South-East Asia have received much
attention. However, the situation seems to be
equally important in Latin America, where the
number of studies is still relatively low, and the
extent and severity of As-exposure in the population only marginally evaluated. Arsenic occurrence in groundwater in Argentina, Bolivia,
Brazil, Chile, Mexico, Nicaragua, Peru, and
other Latin American countries need to be in-
vestigated. Recently, in Nicaragua – a country
where the groundwater arsenic problem was not
assumed to exist – elevated groundwater Asconcentrations as well as As-related health effects were detected. However, the actual number
of people at risk for chronic As-toxicity is not yet
known. This current status of insufficient knowledge on As-occurrence and related health risks
deserves attention.
The sustainable land-use and agricultural practices in the Latin American countries are regionally threatened by the use of As-contaminated
irrigation water. Elevated levels of natural As in
groundwater from geogenic sources is therefore
an issue of primary environmental concern,
which limits the use of these resources for drinking or other purposes, and hinders socioeconomic growth. Hence there is a need to improve our understanding of the genesis of As-rich
groundwaters, constraints on the mobility of As
in groundwater and other environmental compartments, As-uptake from soil and water by
plants, As-propagation through the food chain,
health impacts on human beings, life stock, and
other animals, assessment of environmental
health risks and impacts, and As-removal technologies, to improve the socio-economic status of
the affected regions.
Interdisciplinary Platform Objective
The goal of the international congress "As 2006"
is to bring together geo-scientists, specialists
from public health, from chemical and engineering sciences involved in arsenic-related issues.
The regional focus of attention is dedicated to
Latin America.
The conference serves as a platform for discussion and exchange of scientific knowledge and
ideas to identify future research targets needed to
improve the understanding of (1) the occurrence
and mobility of arsenic in groundwater, (2) the
health impacts and risks when using this water
for drinking or irrigation purposes, and (3) to
develop, evaluate, select and apply the most
suitable remediation methods, which means
adapted to the hydrogeological and hydrogeochemical properties of the aquifer, the specific
hydrochemical composition of the groundwater,
the social conditions and the economic situation
2
of the affected population and the respective
water service providers.
Content
The international congress is designed to (1)
create interest within the Latin American countries, affected by the presence of arseniferous
aquifers, (2) to address the international scientific community in general, (3) to update the
current status of knowledge on the dynamics of
natural arsenic from the bedrock and soils via
aquifers and groundwater to food chain, (4) to
continue the important worldwide forum on
improved and efficient techniques for Asremoval in regions with elevated arsenic levels
in groundwater, and (5) to increase awareness
among administrators, policy makers and company executives, and to improve the international cooperation on that topic. However, we
strongly encourage all other researchers working on arsenic elsewhere in the world to contribute, which would strengthen this global
issue.
Welcome address
1
Author list
3
Abstracts
7
Topic list
89
On behalf of the organizing comittee
Jochen Bundschuh, María Aurora Armienta,
Prosun Bhattacharya , Jörg Matschullat,
Peter Birkle and Ramiro Rodríguez
3
Alphabetical list of authors with page
location in this abstract volume
Acarapi C J ................................................... 21
Acosta-Saavedra L ....................................... 79
Aguilera-Alvarado AF.................................. 15
Aguirre RJ ...................................................... 7
Aguirre V...................................................... 22
Agusto M...................................................... 29
Ahmed KM......................................... 7, 11, 39
Alam MGM .................................................. 80
Alfaro-De la Torre MC................................. 53
Alonso MS.................................................... 50
Altamirano Espinoza M.................................. 8
Andrade G .................................................... 83
Aranyosiová, M ............................................ 19
Arenas H MJ................................................. 21
Armienta MA ................................... 10, 36, 52
Avena M................................................. 43, 64
Ávila Carrera ME ......................................... 28
Balczewski A.................................................. 7
Bandara A..................................................... 84
Banerjee K...................................................... 7
Barberá R...................................................... 42
Barahona F ................................................... 44
Barnes RM.................................................... 88
Barrera A ...................................................... 33
Bastías JM .............................................. 36, 83
Bastida M ..................................................... 79
Beltrán-Hernández RI................................... 45
Berdón V ...................................................... 62
Bhattacharya P...................... 11, 12, 39, 59, 80
Bianco de Salas G......................................... 28
Billib M ........................................................ 37
Birkle P .................................................. 12, 13
Blesa MA...................................................... 24
Bonorino G................................................... 43
Boochs PW................................................... 37
Bovi Mitre G .......................................... 28, 69
Briones-Gallardo R................................. 46, 82
Bruha T......................................................... 27
Bundschuh J ....................11, 12, 13, 44, 54, 80
Caetano LM.................................................. 20
Caldeira C L ................................................. 20
Calderón-Aranda ES..................................... 79
Calderón-Hernandez J ............................ 46, 62
Cama J...........................................................15
Cano-Aguilera I ............................................15
Canyelles C ...................................................16
Carrizales Yañez L..................................46, 62
Caselli AT .....................................................29
Castro de Esparza ML.............................16, 18
Castro-Larragoitia J.......................................53
Caussy D .......................................................19
Cebrián ME.................................26, 45, 52, 79
Cerbon M ......................................................62
Čerňanský S ..................................................19
Chandrajith R ................................................84
Charlet L .................................................64, 65
Chavez C.......................................................22
Choi H...........................................................60
Ciminelli VST.........................................20, 77
Conde P.........................................................79
Cornejo P L .............................................21, 88
Corona M ......................................................70
Cortina JL......................................................16
Cruz L ...........................................................52
Cumbal LH.............................................. 22 (2)
d´Hiriart J ......................................................24
Dahmke A ...............................................40, 41
Daus B...........................................................40
De Haro-Bailón A .........................................31
de Oliveira Couto e Silva N ..............23, 47, 53
de Oliveira Vilhena MJ .................................48
Del Razo LM. 28, 33, 34, 35, 38, 45, 55, 69, 81
Del Río-Celestino M .....................................31
del Valle Hidalgo M................................24, 32
Deschamps E...............................23, 43, 48, 51
Deshpande L .................................................23
Díaz Sch O ....................................................25
Díaz-Villaseñor A ...................................26, 52
Doušová B...............................................26, 27
Driehaus W .....................................................7
Ebert M ...................................................40, 41
Espinosa M................................................8, 28
Esteller MV...................................................49
Estévez J .......................................................81
Etchichury MC..............................................50
Falcón CM ....................................................50
Farías SS .....................................28, 29, 54, 69
Farré R ..........................................................42
Fazio AM ......................................................29
4
Fernández DS ............................................... 32
Fernández RG............................................... 30
Fernández-Cirelli A...................................... 53
Fierro V ........................................................ 88
Figueroa L .................................................... 88
Flores-Valverde E......................................... 10
Font R........................................................... 31
Freitas SHD .................................................. 77
Fuitová L ...................................................... 26
Gabrio T ....................................................... 48
Gaiero D ....................................................... 65
Galindo MC .................................................. 32
Gallaga-Solorzano JC................................... 48
García JW..................................................... 50
Garcia ME .............................................. 13, 54
García MG.............................................. 24, 32
García-Chavéz E........................................... 33
García-Montalvo EA ........................ 28, 34, 81
García-Rico L ......................................... 40, 69
Garcia-Vargas G........................................... 81
Germolec DR................................................ 81
Giarolli F ................................................ 40, 41
Giménez E .................................................... 49
Giordano M .................................................. 35
Giuliano G .................................................... 85
Gonsebatt ME......................................... 35, 62
Grygar T ....................................................... 26
Guadarrama JC ............................................. 33
Gutiérrez Ospina G....................................... 35
Gutiérrez-Ojeda C ........................................ 35
Gutiérrez-Ruiz M ................................... 44, 65
Haque N........................................................ 15
Hasan MA .............................................. 11, 39
Hasan MT..................................................... 59
Helal Uddin M.............................................. 59
Hernández JC ............................................... 51
Hernández H................................................. 36
Hernández M ................................................ 62
Hernández-Ramosa I .................................... 48
Hernández-Zavala A............................... 34, 81
Herrera C ...................................................... 36
Hiriart M................................................. 26, 52
Holländer HM .............................................. 37
Hossain MA.................................................... 9
Hossain MM................................................. 59
Hugo M ........................................................ 57
Izquierdo-Vega JA ........................................38
Jacks G.................................................... 11 (2)
Jakariya M...............................................11, 39
Jara-Marini ME .............................................40
Jiménez I .......................................................33
Jonsson L ......................................................11
Kanel S..........................................................61
Kanel SR .................................................60, 61
Kannel PR .....................................................61
Kinniburgh DG .............................................76
Köber R...................................................40, 41
Koloušek D .............................................26, 27
Königskötter H..............................................66
Korban Ali M..................................................9
Krüger T........................................................37
Kumar M.......................................................59
Laparra JM ....................................................42
Lara-Castro RH.............................................53
Leonhardt Palmiere HE.................................43
Lienqueo A H................................................21
Limbozzi F ....................................................43
Limón JH ......................................................35
Litter MI........................................................24
Lòpez DL ......................................................44
Lopez-Bayghen E..........................................70
López-Carrillo L ...........................................79
López-Sánchez JF ...................................67, 68
López-Zepeda JL ..........................................44
Lucho-Constantino C ..............................45, 55
Luna AL ........................................................79
Lundell L.......................................................11
Machado-Estrada BP.....................................46
Machovič V.............................................26, 27
Maciasa AE...................................................48
Madé B..........................................................85
Mahlknecht J.................................................68
Maldonado Reyes A......................................47
Mansilla H...............................................21, 88
Marcus M ......................................................44
Marijuan L ....................................................51
Mariño E .......................................................73
Martaus A................................................26, 27
Martin RA ...............................................12, 80
Martín Romero F.....................................44, 65
Mata E...........................................................63
Matin Ahmed K ............................................38
5
Matschullat J .......................................... 23, 48
Mattusch J .................................................... 40
Mejia JA ....................................................... 63
Merchant H................................................... 33
Merino MH................................................... 50
Micete S........................................................ 10
Monroy-Fernández MG................................ 82
Monroy-Torres R.......................................... 48
Montero A .................................................... 81
Montero Ocampo C ...................................... 47
Monterrosa J................................................. 44
Montoro M R.............................. 25, 31, 42, 69
Morales L ..................................................... 16
Morales VR .................................................. 62
Morell I......................................................... 49
Moreno C...................................................... 32
Morrison GM................................................ 15
Moscuzza C .................................................. 53
Mridha MAU................................................ 59
Mugica V...................................................... 52
Muñoz O................................................. 36, 83
Nahar S......................................................... 39
Navarrete R .................................................. 35
Navarro C ME .............................................. 62
Nazim Uddin M............................................ 59
Nicolli HB .............................................. 50, 76
Novák M....................................................... 80
Núñez S N .................................................... 25
Oberdá SM ................................................... 51
Orihuela DL.................................................. 51
Ortega MA.................................................... 70
Ortiz E .......................................................... 52
Ostrosky-Wegman P......................... 26, 52, 70
Oswaldo R .................................................... 57
Pande S......................................................... 23
Pant, KK ................................................. 71, 72
Pastene O R .................................................. 25
Pauli C .......................................................... 64
Pažout V ....................................................... 27
Pelallo-Martínez NA .................................... 53
Pérez-Carrera A............................................ 53
Pérez-Mohedano S ....................................... 51
Petrusevski B................................................ 30
Pflüger JC..................................................... 54
Pilar Asta M ................................................. 15
Pimentel A.................................................... 55
Poggi-Varaldo HM..................................45, 55
Ponce RI........................................................28
Pradhan B......................................................56
Preziosi E ......................................................85
Prieto-García F..............................................45
Puigdomènech AP.........................................16
Punti A ..........................................................16
Pupo I............................................................81
Queriol H ......................................................35
Quintanilla J ..................................................57
Rahman IMM................................................59
Ramanathan AL ............................................59
Ramírez E......................................................52
Ramirez P......................................................62
Ransom L ......................................................44
Raßbach K.....................................................48
Recabarren G E .............................................25
Rema P ............................................................9
Reséndiz I......................................................52
Reyes Agüero JA ..........................................46
Rinderknecht-Seijas N ..................................55
Rocha CA......................................................51
Rocha-Amador DO .......................................62
Rodríguez R ............................................36, 63
Rodríguez V ..................................................35
Román-Ross G ........................................64, 65
Ruales J .........................................................69
Rubio R ...................................................67, 68
Rüde TR........................................................66
Ruiz-Chancho MJ ...................................67, 68
Ruiz-Gonzalez Y...........................................68
Sacchi G ........................................................64
Sancha AM........................................16, 68, 69
Sánchez-Peña LC ..............................33, 38, 69
Sánchez-Soto M ............................................26
Sandoval M ...................................................70
Santiago-Garcia EJ........................................48
Sarvinder Singh T ...................................71, 72
Sastre-Conde I...............................................45
Schulz CJ ......................................................73
Segura B........................................................33
Selim HM......................................................74
Senapati K.....................................................75
Sen Gupta AK ...............................................22
Servant RE ....................................................28
Ševc J ............................................................19
6
Shi F ............................................................. 11
Silva A.......................................................... 77
Silva J ........................................................... 43
Silva JCJ....................................................... 77
Smedley PL .................................................. 76
Sordo M........................................................ 70
Soria de Paredes GN..................................... 78
Soriano T ...................................................... 44
Soto-Peña GA............................................... 79
Soto-Peredo CA............................................ 38
Sracek O ..................................... 11, 12, 32, 80
Stummeyer J ................................................. 37
Sulovsky P.................................................... 80
Tineo A......................................................... 50
Tipan R......................................................... 22
Tofalo OR..................................................... 50
Tokunaga S................................................... 80
Torres E ........................................................ 16
Tripathi P...................................................... 59
Urík M .......................................................... 19
Valcárcel L ................................................... 81
Valenzuela OL.................................. 28, 34, 81
Vasconcelos O.................................. 23, 43, 77
Vázquez-Rodríguez G .................................. 82
Vega L .......................................................... 79
Vélez P D ................................... 25, 31, 42, 69
Vieira Alves T .............................................. 51
Vilches S ...................................................... 83
Villaamil E ................................................... 69
Villalobos M........................................... 44, 65
Vithanage M................................................. 84
Vivona R ...................................................... 85
Von Brömssen M.......................................... 11
Wajrak M...................................................... 85
Wallschläger D ....................................... 86, 87
Weerasooriya R ............................................ 84
Weidner U .................................................... 48
Welter E.................................................. 40, 41
Yadav PK ..................................................... 87
Yañez J ................................................... 21, 88
Zhang H........................................................ 74
Zuñiga O....................................................... 62
7
1. Me arsenic adsorption technology
– A review of long-term performance in
full-scale applications from Stadtoldendorf to Phoenix
Roman J. Aguirre1, Kashi Banerjee1, Aaron
Balczewski1, Wolfgang Driehaus2
1
U.S. Filter, 1728 Paonia Street, Colorado
Springs, CO 80915, USA
2
GEH, Germany
In anticipation of the upcoming lower limit
of 10 µg L-1 for Arsenic issued by the
USEPA many utilities and private water
companies are investigating their treatment
options. A recent search of arsenic removal
solutions on the internet identified 307,000
websites pages offering ‘arsenic treatment’.
It can be stated that while most websites
promised the ‘latest and greatest’ solution
to arsenic removal, full scale experience
and commercial availability of many products is non-existent or extremely lacking.
As the plethora of adsorption media and
revolutionary treatment approaches have
gained most of the attention in the market
place, successful, full-scale long-term operating experiences have not been published
for many new technologies.
This paper will in detail focus on longterm, full-scale arsenic adsorption installations in Germany, United Kingdom, India
and the United States. Overall operating
performance, influent and finished water
quality, waste disposal options employed,
site conditions and regional challenges will
be examined and compared. Included in the
analysis are comments from the operating
staff providing their view point of the overall system.
2. Management of shallow groundwater
arsenic: Bangladesh experiences
K M Ahmed
Department of Geology, University of Dhaka,
Dhaka 1000, Bangladesh [email protected]
Presence of arsenic at concentrations above
Bangladesh drinking water standards has
emerged as serious public health hazard
where at least 30 millions people are exposed. This is because of about 30% of
country’s domestic hand tube wells pumping
water with arsenic concentrations above 0.05
mg L-1. Despite enormous variability in spatial and vertical distribution of arsenic in
groundwater, there are certain geological
provinces which are less affected compared
to some severely affected ones. Also there
are certain aquifers which are almost fully
safe compared to others which are almost
entirely unsafe. There are forecasts of significant increase in cancer and other arsenic
related diseases in the coming years. Access
to safe water coverage has come down to
70% from 97% due to arsenic occurrences in
shallow groundwater which is the main
source of potable water in the country.
Since first detection in 1993, lots of activities have been carried out by GOB, UN
agencies, development partners and NGOs.
A large number of research initiatives have
also been taken by local and overseas universities and institutions. A large number of
papers have been published covering various
aspects of the arsenic in groundwater which
have certainly the enhanced the knowledge
base about occurrences, distribution and
remediation of the menace. However, still
there are debates about the origin and release
mechanism and possible consequences of
drinking high arsenic water. And the scale of
mitigation does not match with the magnitude of the problem.
This paper aims to review the existing
knowledge base on various aspects of arsenic occurrences in Bangladesh groundwater
along side critically reviewing the efforts by
8
government and other agencies. As the
arsenic problem occurs in many other countries, particularly in South and East Asia,
Bangladesh experiences would be useful in
designing mitigation strategies in other
countries. For example, Bangladesh has
adopted a National Arsenic Policy and Action Plan for mitigation of the issue. Such a
policy can be adapted to other countries.
Another commendable task carried out by
the World Bank supported Bangladesh
Arsenic Mitigation Water Supply Project is
testing of more than 5 million wells all over
the affected regions of the country. Despite
questions about the validity of such tests
using field kits, there good examples of
using these data is designing village based
mitigation strategy. Also various other research initiatives and mitigation options
can be useful to countries who are trying to
understand and manage the problem.
una extensión de 52 km2. El área comprende
15 comunidades con un total de 3225 habitantes (INEC,1995) y una tasa de crecimiento del 2.6% anual.
Características generales. Las rocas expuestas presentan una intensa alteración hidrotermal. Fallas y fracturas NE y NW próximas a la superficie son verdaderos conductos
y fuentes para que el contaminante entre al
medio acuífero.
Métodos de investigación. Se realizaron
análisis físico-químicos del agua subterránea
y arsénico total en rocas, suelos y aguas. Se
hizo reconocimiento geológico, para conocer
las condiciones geomorfológicos, estructurales y la zonificación de la alteración hidrotermal. Se usó geofísica (magnetometría)
para identificar posibles estructuras asociadas a las concentraciones de As en las
aguas subterráneas.
Principales hallazgos.
3. Distribución de la contaminación
natural por arsénico en las aguas
subterráneas de la subcuenca Suroeste
de El Valle de Sebaco-Matagalpa,
Nicaragua
M. Altamirano Espinoza
Centro para la Investigación de Recursos
Acuáticos –Universidad Nacional Autónoma de
Nicaragua (CIRA/UNAN), Managua 4598
Nicaragua; [email protected]
Un problema ambiental serio en Nicaragua
es la concentración natural de arsénico en
las aguas subterránea próximos a áreas
mineralizadas por procesos hidrotermales
producto de la dinámica de Nicaragua Occidental, donde el proceso de subducción
de la placa de Cocos por debajo de la placa
del Caribe es el motor principal de la formación de la Depresión de Nicaragua, la
principal estructura geológica regional, en
cuyo margen oriental externo ocurre el
Valle de Sébaco y el área de estudio en la
parte SW. Entre estas áreas podemos ubicar
la parte suroeste del Valle de Sébaco, con
1- Las principales concentraciones de arsénico en roca, suelo y agua se asocian a
procesos singenéticos (primarios) y epigenéticos (secundarios), evidenciados a lo largo
de fallas y fracturas NE y E-W principalmente.
2- Desde el punto de vista físico químico, las
muestras analizadas en los 25 pozos
estudiados son consideradas aguas de buena
calidad. (CAPRE,1994). Un total de 16 pozos (64%) se clasifican como aguas bicarbonatadas cálcicas.
3- Las mayores concentraciones de arsénico
se encuentran asociadas a sistemas de fallas
secundarias E-W las cuales favorecen la
formación de micro estructuras que influencian las características propias del acuífero
especialmente el espesor y la profundidad
del basamento.
4- De los 57 muestras de agua captadas, el
36% presentan concentraciones de arsénico
total (10 a 122 µg L-1) que sobrepasan el
valor guía establecidos para agua de consumo humano. En el 93% de las muestras de
9
aguas, el arsénico se encuentra como arsenatos con un estado de oxidación (V) y el
7% se encuentran como arsenito (III), el
cual es la especie más toxica y móvil de
arsénico.
5- En la comunidad de El Zapote se encontraron las mayores concentraciones de
arsénico. En rocas y suelos, las concentraciones de arsénico total detectadas fueron
de 14.98 µg g-1 y 57.19 µg g-1 respectivamente, en el agua fue de 122.15 µg L-1.
Dos muestras comparativas de suelo,
ubicadas fuera del área de estudio, en la
entrada a Mina La India y en los
alrededores de la comunidad Agua Fría,
presentaron concentraciones mayores y
similares a la de El Zapote con concentraciones de 95.2 y 59.5 µg g-1 respectivamente
6- La presencia de arsénico en los suelos
evidencia el origen desde fuentes naturales.
El contacto de la población con el xenobiótico ocurre de forma permanente no solo
en la ingesta de agua si no en su actividad
cotidiana incrementando el riesgo toxicológico.
4. Unacceptability of the Two Bucket
Arsenic Removal Filter in Dhobawra,
Bangladesh
M. Anwar Hossain1, Pulok Rema2 and M.
Korban Ali2
1
Department of Farm Structure, Faculty of
Agricultural Engineering & Technology, Bangladesh Agricultural University, Mymensingh2202, Bangladesh
2
Faculty of Agricultural Engineering &
Technology, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh;
[email protected]
This study aimed to determine the reasons
why people unaccepting the arsenic removal technology (two bucket filter) and
the causes why people return back for using
tubewells water instead of arsenic removal
technology’s water. Data were collected by
using an interview schedule from 85 users
from Ghosh Gaon union under Dhobawra
upazilla of Mymensingh district, Bangladesh
between the times of Jan/2004 to Feb/2005.
The most of the users are middle aged illiterate low income farmers. The large percent of
respondent (50.3%) has no knowledge about
arsenic diseases. There were no social/family
problem faced by the users during using of
two bucket filter and has no arsenic patients.
Only 12.9% of the tubewells are bearing
arsenic concentration over danger level. The
unacceptability index (U.I) of 10-items of
arsenic removal unit (two bucket filter
method) ranged from 110.6 to 295.3 against
a possible range 0 to 300. The score of 6 U.I
exceeded 250. Among the causes ‘Very low
flow of water through two bucket filter’ was
found high unacceptability index (U.I) of
295.3, while, ‘Repair-Maintenance and Replacement of Sand, Coal and brick particles
is not available’ was second ranked order
(UI =287.2), ‘More time required to fill up a
Jar of water’ the third (U.I = 286) and ‘Easily Block out of filters and Screens’ the
fourth ranked order (U.I = 284.9). However,
all the remaining indices of unacceptability
were found above 150 except one which was
110.6. From the overall unacceptability of
the users revealed that 18.8 percent of users
shown medium high unacceptability, 63.5
percent users high and 17.6 percent very
high unacceptability. There is 100 percent
users’ currently consuming tubewells water
from their own tubewells. The acceptability
index (A.I) revealed that the No. 1 rank order obtained by the statements of ‘water is
clean and pure’ with an acceptability index
of 298.4. The No. 2 and No. 3 rank order
obtained by the statements of ‘Water is safe
for use and ‘Easily available in all time’ with
the acceptability index of 296.5 and 268.1
respectively. From the overall acceptability
it is found that 32.9 percent of users have
highly accepted the tubewells water instead
of two balti method, 64.7 percent users’ medium highly and only 2.4 percent users’ medium accepted.
10
These research findings has recommended
to the decision makers and NGO for evaluating the unacceptability and sustainability
before supplying or install the arsenic removal technology in a particular area.
5. Feasability of arsenic removal from
polluted water using indigenous geological materials
M.A. Armienta1, S. Micete2, E. FloresValverde2
1
Instituto de Geofísica, Universidad Nacional
Autónoma de México. Circuito Exterior C.U.,
México 04510 D.F.
[email protected]
2
Posgrado en Ciencias e Ingeniería Ambientales, Universidad Autónoma Metropolitana,
México D.F.
Arsenic concentrations above the Mexican
drinking water standard have been measured in deep wells used for potable supply
at Zimapán, México. Arsenic contamination in these wells is produced by natural
processes. Lack of productive non-contaminated wells and surface water bodies in the
area, gives few alternatives to As pollution.
Currently, good quality water from a well
located about 25 km from Zimapán, is
pumped 400 m height and mixed with water from a well (Z5) containing 0.5 mg L-1
As, to supply potable water. Variations on
the proportion of water from each source
results on variable As concentrations, being
0.15 mg L-1 in February 2005. Iron oxides
and zeolites are the geological materials
most used to remove arsenic at other polluted sites. However, the geology of Zimapán with abundant limestone outcrops,
prompted to study their As removal potential. Besides, previous studies have shown
the capacity of limestones from this area to
remove arsenic.
The feasibility of the Soyatal limestone to
produce clean water from the deep well Z5
was determined with batch and column
tests. Batch tests were performed varying
time, rock: water ratio, and rock sizes. Results showed a 90% decrease on the arsenic
concentration treating 1 liter of water with
10 g rock of a size <0.5 mm. Experiments
were run during one hour, but removal took
place within the first minutes. Clean water
was removed and contaminated water was
again added to the same rocks. This procedure was repeated several times, obtaining
the same efficiency of As removal up to the
fifth addition of water. Use of rock particles
0.84-1.00 mm decreased As content to 0.057
mg L-1 or less, within 5 minutes. Particle size
played a relevant role in the column experiments. Use of particles <0.5 mm hindered
the water flow. Packing with rocks 0.84 mm
to 1.00 size allowed an adequate water flow,
and produced an As concentration of 0.025
mg L-1 in the outflow.
Use of the Soyatal limestone rocks at Zimapán has several advantages: this type of
rock is abundant in the area, is of easy harvesting and of easy milling. Limestones may
be used for a domestic water-treatment. The
same rocks may be used five times to clean
new batches of contaminated water. Packed
columns may be used on site to treat the
water pumped from the polluted wells.
Waste rocks may be disposed on tailings
located at Zimapán town, and contribute to
increase their pH and control acid mine
drainage.
11
6. Targeting safe aquifers in Matlab Upzila, Bangladesh – Validating the initiatives of local drillers
P. Bhattacharya1, M. von Brömssen1, M.
Jakariya1,2, L. Jonsson1, L. Lundell1, G.
Jacks1, K.M. Ahmed3 and M. A. Hasan3
1
KTH-International Groundwater Arsenic
Research Group, Department of Land and
Water Resources Engineering, KTH, SE100 44 Stockholm, Sweden; [email protected]
2
NGO-Forum for Drinking Water Supply
and Sanitation, 4/6, Block-E, Lalmatia,
Dhaka 1207, Bangladesh
3
Department of Geology, Dhaka University,
Natural arsenic (As) is encountered in
groundwaters from the shallow aquifers of
Holocene age in Bengal Delta Plain (BDP)
of Bangladesh above the safe drinking water standard of WHO (10 µg L-1). Groundwaters with elevated As levels are abstracted. In our ongoing studies in Matlab
Upazila of SE Bangladesh, it is observed
that local drillers prefer to install tube wells
based on the characteristics of the aquifer
sediments. The present paper attempts to
link the groundwater composition to the
redox characteristics of the sediments that
would validate the initiatives of the local
drillers to identify and target the relatively
oxidized aquifers for installation of As-safe
tube wells.
The Holocene aquifers in Matlab Upazila is
characterized by a sequence of sediments
with considerable heterogeneity in terms of
grain size, color and mineralogy. In general, a thick layer of grey (herein after referred to as black) sediments with thickness
varying between 40-50 m, overlies a sequence of sediments characterized by
white, off-white and red colors. The
groundwater is near-neutral (pH = 6-7) and
predominantly of Ca-Mg-HCO3 or Na-ClHCO3 type. The groundwater was generally
reducing with low concentrations of SO42and NO3- but with high concentrations of
Fetot and Mn. The concentration of Astot
range between below detection limit to 355
µg L-1. The groundwater samples were classified in accordance with the four groups of
the color of the sediments (black, white,
offwhite and red) at the screen depths of the
wells. Four different groups of sediments
were characterized by a distinct scale of
groundwater composition governed by the
redox characteristics.
Groundwater extracted from black sediments
was most reduced, followed by white, offwhite and red where the groundwater was
less reduced. The reddish/yellowish color of
the sediments and low concentrations of
dissolved Fe in groundwater at these depths
suggest a relatively oxidised condition. In
these sediments, most of the Fe is likely to
be present as coatings on the framework
grains as oxyhydroxides, which impart reddish/yellowish colour to these sediments,
thereby have the ability to adsorb As. We
believe that it is possible to target safe aquifers by combining the indigenous knowledge
and techniques of the local drillers along
with modern geological and hydrogeochemical expertise.
7. Groundwater characteristics in the
shallow aquifers of Huhhot region in Inner Mongolia, PR China: Implications on
the mobilisation of arsenic
Prosun Bhattacharya1*, Fei Shi1, Ondra Sracek2,
Gunnar Jacks1 and Jochen Bundschuh3
1
KTH-International Groundwater Arsenic Research Group, Department of Land and Water
Resources Engineering, Kungliga Tekniska Högskolan, SE-100 44 Stockholm, Sweden;
[email protected]
2
Institute of Geological Sciences, Faculty of
Science, Masaryk University, Kotlařská 2, 611
37 Brno, Czech Republic
3
Instituto Costarricense de Electricidad, Apartado
Postal 10032, 1000 San José, Costa Rica
Elevated arsenic (As) concentration in
groundwater is becoming a worldwide problem. In Huhhot Alluvial Basin (HAB) in
12
Inner Mongolia, People’s Republic of
China, a population of over a million is
exposed to severe health risk due to the
consumption of groundwater with high As
concentration. In some arsenic seriously
affected areas, As concentration reach 1491
µg L-1, 149 times over WHO’s drinking
water guideline value for As and exceed the
Chinese drinking water standard by a factor
of 30 times. Due to the acute shortage of
safe water supply and inefficient water
management system, people are compelled
to drink groundwater with high As concentration. Long period ingestion of water with
high As concentration have lead to chronic
arsenic poisoning among the residents of
the region. This present work deals with the
hydrogeochemical characterisation of the
groundwater of the shallow alluvial aquifers and their implications on the chemistry
and its relation to the mechanism of As
mobilization in the HAB.
Groundwater samples were collected during October 2003, from 29 sites in the village of Tie Men Jing, located about 100 km
from Inner Mongolia’s capital Huhhot. The
pH, redox potential (Eh), temperature and
electrical conductivity were measured at
sites while major ions, trace elements including As total and As (III) were analyzed
in laboratories at the Royal Institute of
Technology and Stockholm University in
Sweden. Groundwater is generally neutral
to alkaline and the pH varies from 6.67 to
8.7. The redox potential (Eh) lies between
74 and 669 mV. The electrical conductivity
(EC) range varies from 581 to 5200 µS cm1
. Temperature ranges from 9.1 to 13.5 °C.
Depths of wells are from 4 m to 75 m.
Groundwater is mostly of Na-Mg-HCO3Cl-type and dominated by HCO3- and Cl- as
the predominant anions. The concentrations
of SO42- range between 0.3 and 172.8 mg L1
and there is a trend of decreasing sulfate
concentrations with increase in well depth.
The levels of NO3- were lower than the
WHO´s guideline value of 50 mg L-1 in 27
wells. These high NO3- concentrations
could have been caused by anthropogenic
contamination due to the sanitation practices.
The PO43- concentration ranges between 0.04
to 2.6 mg L-1.
Total As concentration ranged from below
detect limit (5.2 µg L-1) to 141 µg L-1. In 28
of the investigated wells, As levels exceeded
WHO’s guideline value 10 µg L-1 and 17
wells exceeded Chinese standard 50 µg L-1.
Among the 42 groundwater samples of the
shallow aquifers only three complied with
the WHO drinking water guideline value for
As. The dominant species in the groundwater
was As (III). In the 29 wells of Tie Men
Jing, the concentration of Fe and Mn –
exceeded the WHO’s guideline value by a
factor of 10.
The aquifers are composed of Quaternary
(mainly Holocene) fluvial and lacustrine
sediments. High As occurring in anaerobic
groundwater in low-lying areas is associated
with high concenrations of dissolved Fe and
Mn. Improved water supply system, employment new water and energy resources,
poverty fighting and expertise cooperation
are recommended to solve Huhhot basin
rural area’s drinking water problem.
8. The abundance of natural arsenic in
deep thermal fluids of geothermal and
petroleum reservoirs in Mexico
Peter Birkle1 and Jochen Bundschuh2
1
Instituto de Investigaciones Eléctricas, Gerencia
de Geotermia, Avenida Reforma 113, Col.
Palmira, Cuernavaca, 62490 México;
[email protected]
2
Instituto Costarricense de Electricidad ICE,
Apartado Postal 10032, 1000 San José, Costa
Rica
In general, little data is available on the
metal and non-metal composition of thermal
groundwater in Mexican geothermal and
petroleum reservoirs. The abundance of
hydrothermal minerals at the volcanic reservoir of the Los Azufres geothermal field
(State of Michoacán, Central Mexico), as
13
well as arsenic concentrations between 5.1
mg/L and 24.0 mg L-1 in geothermal brines
indicate the importance of dissolution and
exchange processes between hot fluids and
arsenic-enriched host rock. Elevated natural
arsenic concentrations of up to 3.9 mg L-1
in surface manifestations - hot springs and
fumaroles - are probably related to the vertical ascent of convective fluids towards the
surface. Deep waters from the Los Humeros geothermal field, located in the eastern part of the Transmexican Volcanic Belt,
show a depth-related increase of arsenic
concentrations from 3.9 mg/L (e.g., Well
H-1) towards 162 mg L-1 (Well H-12).
Lower mineralized waters form part of a
liquid-dominated, bicarbonate reservoir
type at a depth from 1,025 m to 1,600 m
a.s.l., whereas deeper wells (800 – 100 m
a.s.l.) produce a two-phase fluid. Arsenicbearing minerals are not reported. The
dominance of sandstones in the sedimentary basin of the Cerro Prieto geothermal
field, State of Baja California, NW-Mexico,
explains the presence of relatively low Asconcentrations from 0.25 to 1.5 mg L-1 in
reservoir fluids, although bottomhole temperatures are extremely elevated (max.
370°C). In order to avoid environmental
impacts of arsenic-enriched, deep geothermal fluids with the surface environment, it
is essential to maintain a closed production
cycle between extraction wells, energy
generation and reinjection wells.
In contrast, deep fluids from petroleum
reservoirs in SE-Mexico are less enriched
in arsenic in comparison to geothermal
reservoir fluids in Mexico. The reservoirs
of Pol-Chuc, Abkatun, Batab, Caan, and
Taratunich, located 80 km off-shore the
Gulf coast, reach maximum Asconcentrations of 2.01 mg/L at a depth
from 2,910 to 4,658 m b.s.l. Formation
water from the Cactus, Nispero and Sitio
Grande oil reservoirs (State of Tabasco) are
located at a depth from 3,670 to 4,315 m
b.s.l. Although mineralization of these fluids can reach hypersaline conditions (up to
257,000 mg L-1 TDS), arsenic concentrations
(< 0.003 to 0.047 mg L-1) are relatively low.
This effect can be attributed to the carbonate
host rock type – calcareous sandstone, dolomitized mudstone and brecciated and fractured dolomite units from lower-upper Cretaceous period - with little ore content and
hydrothermal mineralization. Relatively lowtemperature reservoir conditions around
130°C prevent major geochemical reactions.
Concluding remarks about the origin of arsenic in Mexican deep reservoirs, the studied
geothermal fluids are strongly affected (Los
Azufres and especially Los Humeros fluids)
by water-rock interaction processes under
elevated temperatures conditions (> 280°C).
Although fluid salinization is relatively low
(maximum TDS: 15,000 and 2,000 mg L-1,
respectively), the combination of physical
and chemical conditions causes an enrichment in metal and non-metal concentrations
In contrast, low saline to hypersaline waters
in Mexican oil reservoirs (maximum TDS:
257,000 mg L-1) are less concentrated in
arsenic, which must be attributed to the
sedimentary host rock type and lower temperatures conditions.
9. Rural Latin America —A forgotten
part of the global groundwater arsenic
problem?
J. Bundschuh1, M.E. García2, P. Birkle3
International Technical Cooperation Program,
CIM (GTZ/BA), Frankfurt, Germany —Instituto
Costarricense de Electricidad (ICE), UEN, PySA,
Apartado Postal 10032, 1000 San José, Costa
Rica; [email protected]
2
Instituto de Investigaciones Químicas,
Universidad Mayor de San Andrés, P. Box
10201, La Paz, Bolivia,
[email protected]
3
Instituto de Investigaciones Eléctricas, Gerencia
de Geotermia, Avenida Reforma 113, Col.
Palmira, Cuernavaca, 62490 México
In different countries of Latin America as
Argentina, Chile, México, and Peru at least 4
million people are permanently drinking
14
water with elevated arsenic concentrations
in a magnitude, which converts the issue in
some of the countries as in Argentina and
Mexico into a public health problem. So
e.g. in Argentina and Chile over 1% of the
population is exposed to the problem,
whereas in Bolivia, Brazil, Ecuador, Costa
Rica, El Salvador, and Guatemala, arsenic
in drinking water is proved, but the
numbers of persons affected are yet
unknown. In other Latin American
countries, the existence of the groundwater
arsenic problem is not yet known. This was
for example the case of Nicaragua where
the arsenic exposure of population from
groundwater and related severe health
effects, was detected just two years ago.
Additionally it must be taken into account
that with advances in the modern analytical
methods for arsenic at low levels of
concentrations, and with the introduction of
new national arsenic limits of 0.01 mg L-1,
as already introduced by Nicaragua and
being planned to be implemented Mexico,
it is expected that in future arsenic will be
detected also in several countries with
elevated concentrations, where it was
presumed until now to be arsenic safe, and
that numbers of people exposed will
significantly increase.
Although that the arsenic drinking water
problem is already solved in most urban
areas by installing corresponding treatment
plants, practically no action was performed
by the authorities or international and
bilateral cooperation agencies to mitigate
the arsenic problem for the rural
population, making especially the dispersed
living rural population, which drinks
arsenic-contaminated water — often
without being aware of its toxicity — to the
most disadvantaged group and to an
emerging target for further actions to
reduce the arsenic exposure.
In most of the these countries, the problem
is of natural origin, related to arsenic occurrence in groundwater containing up to
several mg As L-1, used for drinking water.
In decreasing order of importance, it is either
related to (1) the presence of arsenic in the
aquifer sediments, related to volcanism
(Argentina, Bolivia, Chile, Peru, Nicaragua,
Mexico, El Salvador), (2) mining activities
(Chile, Bolivia, Peru, Mexico), (3) electrolytic metal producing processes (Brazil), and
(4) agricultural activities (arsenic containing
pesticides).
This paper comprises of 3 parts: First it gives
a country-by-country state of art overview
on the occurrence of arsenic in the
groundwaters and surface waters used for
drinking purposes in Latin America,
including the respective arsenic sources, the
numbers of persons exposed and affected,
and the respective already observed and
future possible health effects. In each case
the need and the possibilities of mitigating
the impact are discussed.
The second part discusses the experiences
from the until now applied remediation
methods for both, applications in urban and
rural areas, and the third block deals with
future needed measures to mitigate the
drinking water arsenic problem of "Rural
Latin America". Therefore remediation
methods as well as the identification of safe
water resources free of arsenic are addressed
as possible solutions.
Special emphasis is drawn on the fact, that
—at first— it is not a technological problem
to be solved. First, the local, national authorities of the affected countries and the
bilateral or international cooperation agencies must recognize groundwater arsenic in
the rural areas of Latin America as one of the
most important natural health risks of the
present century. They must recognize that
groundwater arsenic is an issue and a problem that would challenge the UN Millennium Development Goals of sustainable
development on a global scale, and therefore
consider doing its utmost to better equip
people for life in those parts, where groundwater arsenic affects population and their
sustainable development.
15
In order to mitigate the groundwater arsenic
problem in rural areas, it must be considered, that the most sustainable strategies for
the management of water supply systems
are executed by the communities itself.
Such is especially applicable in rural areas
with small communities. It requires participatory development strategies comprising
community consultation for problem definition, involvement in investigation and planning and in the execution and maintenance
of the constructions. This needs a strong
technical assistance or expertise. Often with
little education and assistance, communities
can be highly motivated to take action to
develop and manage local water infrastructure in a sustainable way. If this is not
achieved, even successful arsenic remediation programs may be abandoned soon by
the local users, as it could be recently observed in the case study of Nicaragua.
10. Preliminary results on the dissolution
kinetics of arsenopyrite (FeAsS)
Jordi Cama and Maria Pilar Asta
Institute of Earth Sciences “Jaume Almera”,
CSIC; Barcelona, E-08028 Catalonia, EU
Arsenopyrite oxidative dissolution contributes arsenic to waters. The effects that environmental factors (e.g., pH, content of iron
and sulphate, dissolved oxygen and surface
reactivity) exert on the arsenopyrite decomposition are studied by means of nonstirred flow-through experiments at pH
from 1 to 3 and variable DO content.
Steady-state dissolution rates are calculated
based on the release of arsenic and iron into
solution. In the pH range studied proton
concentration has no or little influence on
the arsenopyrite dissolution. On the contrary, the decrease in dissolved oxygen
concentration up to PO2 approx. 0%
strongly diminished the arsenopyrite rate at
pH 3.
Arsenic and iron species in solution (e.g.,
As(III), As(V), Fe(II), and Fe(III)) may be
present in solution and affect the arsenopyrite dissolution. Moreover, the toxicity of an
arsenic rich solution will depend on the oxygen content interacting with either the arsenopyrite surface or with solutions.
Ongoing experiments are aimed to obtain the
temperature effect on the arsenopyrite dissolution rate. Nanoscale techniques, such as in
situ AFM experiments and XPS surface
analysis will be used to understand the
mechanisms governing the overall oxidative
dissolution reaction.
11. Fe-modified light expanded clay aggregates (LECA) for the removal of arsenic from aqueous solutions
Irene Cano-Aguilera1*, Nazmul Haque1,2, Alberto F. Aguilera-Alvarado1 and Gregory M.
Morrison2.
1
Facultad de Química, Universidad de Guanajuato, Noria Alta S/N, C.P. 36050, Guanajuato,
Gto., México; [email protected]
2
Water Environment Transport Department,
Chalmers University of Technology, SE-41296,
Göteborg, Sweden
Iron modified materials have been proposed
as a filter medium to remove arsenic compounds from groundwater. This study was
investigated the removal of arsenic from
aqueous solutions by iron-coated light expanded clay aggregates (LECA). Kinetic experiments were performed to investigate the
sorption mechanisms. More than 80% of arsenic adsorbs to Fe-LECA within one hour.
Equilibrium is slowly approached within the
next 5 hours. At equilibrium, low redox potential and a pH value of >6.0 clearly represents a favorable media (iron hydroxides) to
adsorb arsenic by Fe-LECA. The experimental data fitted the pseudo-first-order equation.
For a 1 mg L-1 of arsenic concentration, the
rate constant k1 of pseudo-first-order was
0.098 min-1 that represents a rapid adsorption
to reach equilibrium early. Surface complexation and ion exchange proposed to be the
major arsenic removal mechanisms. Column
16
experiments were conducted under different
bed depths, flow rates, coating duration and
initial iron salts concentration for coating
were tested to optimize the arsenic removal
efficiency by Fe-LECA column. Volumetric
design as well as higher hydraulic detention
time was proposed to optimize the efficiency
of the column to remove arsenic. In addition,
concentrated iron salts and longer coating
duration was also found very influencing
parameter for arsenic removal. The maximum arsenic accumulation was found 3.31
mg of As g-1 of Fe-LECA when the column
was operated at a flow rate of 10 ml min-1
and the LECA was coated with 0.1M FeCl3
suspension for 24 h coating duration.
12. Evaluación de alternativas a la
mejora de la calidad del agua de pozos
en las comunidades rurales de San Juan
de Limay, Nicaragua
Caterina Canyelles1, Ester Torres1, Laura
Morales1, Clàudia Puigdomènech1, Anna Punti1,
Jose Luis Cortina1, Ana Maria Sancha2
cación de algunas medidas de fácil uso y
bajo costo para mejorar la calidad del agua
en esta zona rural de bajos ingresos.
El presente trabajo presentará los estudios
realizados para determinar el nivel de contaminación de una serie de pozos de las
comunidades afectadas de San Juan de Limay y una primera aproximación a la identificación del origen del As en las aguas.
Finalmente el trabajo proporciona una serie
de recomendaciones para la remoción de las
aguas de los contaminantes identificados,
especialmente del arsénico.
13. Presencia de arsénico en el agua de
bebida en América Latina y su efecto en la
salud pública
María Luisa Castro de Esparza
Asesora Regional en Aseguramiento de la
Calidad y Servicios Analíticos. CEPIS / SDE /
OPS; Calle Los Pinos 259, Urbanización
Camacho, La Molina, Lima, Perú;
[email protected]
1
Department of Chemical Engineering , Universitat Politècnica de Catalunya, ETSEIB, Av.
Diagonal, 647, E-08028 Barcelona (España);
[email protected]
2
División de Recursos Hídricos y Medio
Ambiente, Facultad de Ciencias Físicas y
Matemáticas, Universidad de Chile, Santiago,
Chile
En los últimos años el centro de Salud de
San Juan de Limay, que atiende a decenas
de miles de persona anualmente, ha establecido que el agua de algunos pozos de las
comunidades del municipio está contaminadas. La población tiene enfermedades con
síntomas característicos de elevada presencia de microorganismos patógenos, y muy
posiblemente de arsénico, además de otros
contaminantes. Con objeto de tomar medidas urgentes, el centro de salud del MINSA
(Ministerio de Salud) promovió el estudio
de evaluación de la calidad del agua de
diferentes pozos ubicados en las comunidades campesinas afectadas, estudiar la apli-
En varios países de América Latina como:
Argentina, Chile, México, El Salvador;
Nicaragua, Perú y Bolivia por lo menos
cuatro millones de personas beben en forma
permanente agua con niveles de arsénico que
ponen en riesgo su salud en tal magnitud que
en algunos de los países se ha convertido en
un problema de salud pública.
Este trabajo constituye una recopilación
bibliográfica de la problemática del arsénico
en el agua de bebida y sus efectos en la salud
de las personas expuestas. Situación que se
necesita atender a fin de minimizar sus
efectos y disminuir el arsenicismo en las
zonas afectadas.
Se describe la presencia del arsénico en el
ambiente y en las fuentes de agua para
consumo humano se debe a factores
naturales de origen geológico (México,
Argentina, Chile, Perú, Nicaragua) a
actividades antropogénicas que involucran la
explotación minera y refinación de metales
17
por fundición (Chile, Bolivia y Perú),
procesos electrolíticos de producción de
metales de alta calidad como cadmio y cinc
(Brasil), y en menor proporción en la
agricultura en el empleo de plaguicidas
arsenicales orgánicos (México).
Como se conoce en la mayoría de los casos
la presencia de arsénico en aguas superficiales y subterráneas de América Latina es
natural y está asociada al volcanismo terciario y cuaternario desarrollado en la Cordillera de Los Andes. Proviene de la
disolución de minerales, la erosión y desintegración de rocas y por deposición atmosférica (aerosoles). En el agua puede encontrarse en su forma trivalente y pentavalente.
En el agua de bebida, por lo general el
arsénico se encuentra en la forma de
arsenato y puede ser absorbido con
facilidad en el tracto gastrointestinal en una
proporción entre el 40 y 100%. El arsénico
inorgánico ingerido es absorbido por los
tejidos y luego se elimina progresivamente
por metilación a través de los riñones, en la
orina. Cuando la ingestión es mayor que la
excreción, tiende a acumularse en el cabello y en las uñas.
Las principales rutas de exposición de las
personas al arsénico son la ingesta e inhalación. Es acumulable en el organismo por
exposición crónica, y a ciertas concentraciones ocasiona alteraciones de la piel con
efectos secundarios en los sistemas nervioso,
respiratorio, gastrointestinal, y hematopoyético y acumulación en los huesos, músculos y
piel, y en menor grado en hígado y riñones.
Estudios toxicológicos y epidemiológicos
confirman la información anterior e indican
que la ingestión crónica de arsénico en el
agua de bebida genera lesiones en la piel, la
hiperpigmentación e hiperqueratosis palmo
plantar; desórdenes del sistema nervioso;
diabetes mellitus; anemia; alteraciones del
hígado; enfermedades vasculares, cáncer de
piel, pulmón y vejiga.
El consumo de agua con arsénico a largo
plazo conlleva a efectos crónicos y a la generación de arsenicismo. El tratamiento involucra proporcionar al paciente agua de
bebida libre de arsénico. El siguiente paso es
monitorearlo y asegurarse de que no esté
expuesto a este elemento. Otros tratamientos
propuestos son la quelación y la mejora de la
nutrición.
Su toxicidad depende del estado de oxidación,
estructura química y solubilidad en el medio
biológico. La escala de toxicidad del arsénico
decrece en el siguiente orden: arsina > As+3
inorgánico > As+3 orgánico > As+5 inorgánico
> As+5 orgánico > compuestos arsenicales y
arsénico elemental. La toxicidad del As+3 es
10 veces mayor que la del As+5 y la dosis
letal para adultos es de 1-4 mg As kg-1. Para
las formas más comunes como AsH3,
As2O3, As2O5 esta dosis varía en un rango
entre 1,5 mg kg-1 y 500 mg kg-1 de masa
corporal.
Se ha demostrado que los niños son más
sensibles que los adultos a la toxicidad por el
arsénico y son los más afectados por el arsenicismo, por problemas de desnutrición y
precario saneamiento en las zonas rurales
dispersas (pobres). La población más
afectada es la población dispersa ubicada en
el área rural que consume agua sin ningún
tratamiento y desconoce el riesgo al que está
expuesta. Se requiere que las autoridades de
salud, ambiente y saneamiento planifiquen
los servicios de aprovisionamiento de agua y
promuevan e intervengan en la ejecución de
programas de prevención y control de riesgos del consumo del agua de bebida con
niveles de arsénico superiores a los recomendados. Los programas deben involucrar la participación de las autoridades,
comunidad y sistemas locales de salud.
18
14. Remoción del arsénico en el agua para
bebida y biorremediación de suelos
tiva (arcilla verde natural, arcillas activadas,
zeolita natural y activada y carbón de hueso.
María Luisa Castro de Esparza
Chile es el país con más experiencia en el
tratamiento de agua para distribución urbana,
cuentan con cuatro plantas de remoción de
arsénico del agua de abastecimiento (0,40 µg
L-1) que tratan en conjunto 2000 L s-1 y
producen agua potable con 0,040 mg As L-1.
Han evaluado la mejora del sistema agregando osmosis inversa (postratamiento) y
desalinización. En Perú hay una planta de
remoción de arsénico que trata el agua con
cloruro férrico y ácido sulfúrico.
Asesora Regional en Aseguramiento de la
Calidad y Servicios Analíticos. CEPIS / SDE /
OPS; Calle Los Pinos 259, Urbanización
Camacho, La Molina, Lima, Perú;
[email protected]
Varios países de América han reportado la
existencia de población expuesta crónicamente a concentraciones de arsénico en
agua de bebida, superiores a las previstas
por la normatividad de los países. Es el
caso de Canadá, Estados Unidos, Chile,
Perú, Bolivia, México, El Salvador y Nicaragua. Algunos de estos países han resuelto
total o parcialmente el problema de disposición de tecnología, dependiendo de que
la población afectada fuera rural o urbana.
Existen alrededor de 14 tecnologías para
remover arsénico del agua con eficiencias
del 70 al 99%. Los métodos de coagulación-floculación y ablandamiento con cal,
son los más usados en grandes sistemas y
no exclusivamente para remover el arsénico. En pequeños sistemas pueden ser
aplicados el intercambio iónico, alúmina
activada, osmosis inversa, nanofiltración y
electro diálisis inversa. Las tecnologías
emergentes son: arena recubierta con óxidos de hierro, hidróxido férrico granular,
empaques de hierro, hierro modificado con
azufre, filtración con zeolita, adición de
hierro con filtración directa y remoción
convencional de hierro y manganeso.
En Latinoamérica los estudios han estado
orientados al uso de la coagulación
química: con sulfato de aluminio, cal
hidratada y poli electrolito de sodio y han
logrado tenores de arsénico a 0,12-0,15 mg
L-1. Con coagulación directa sobre filtro y
con coagulación-floculación han logrado
alcanzar valores bajo 0,05 mg L-1. En la
remoción mediante adsorción han empleado hematitas y materiales con alto contenido de hierro y superficies de carga posi-
El CEPIS/SDE/OPS, ha desarrollado y patentado el producto ALUFLOC que es una
mezcla de un oxidante, arcillas activadas y
un coagulante (sulfato de aluminio ó cloruro
férrico). Es una metodología simple y de
bajo costo que permite remover a nivel
domiciliario el arsénico natural presente en
las aguas subterráneas que son usadas como
agua de bebida por la población rural. Se
lograron niveles de remoción de hasta un
98%, usando como coagulantes Al2(SO)3.
and FeCl3.
Para la remediación de suelos de zonas contaminadas se ha estudiado la capacidad de
algunos vegetales para absorber y concentrar
las sustancias tóxicas. La Universidad de
Florida ha identificado un helecho que absorbe arsénico del suelo contaminado que
hiper acumula este elemento.
Las tecnologías de recuperación y estabilización de arsénico en lodos, suelos y
residuos de actividades industriales por lo
general son precipitados con cal y soda cáustica. Luego separación por sedimentación
y/o filtración. En México han obtenido un
compuesto de arsénico insoluble y que también se puede emplear como materia prima
en la formulación de productos solidificados
para ser usados en construcción o dispuestos
en un relleno sanitario.
Para afrontar la problemática del agua de
bebida, se debe tener en cuenta las características de las fuentes, la adecuación del
19
agua, forma de distribución y/o consumo y
las variantes de la tecnología a emplear
considerando las características propias del
lugar.
En los países de Latinoamérica existe experiencia y capacidad para el desarrollo de
tecnología, pero limitada por la carencia de
recursos financieros, facilidades y sobre
todo políticas de estado que faciliten y orienten el desarrollo de la tecnología que
conlleve a la solución efectiva de problemas o satisfacción de las necesidades existentes.
La población más afectada se encuentra
dispersa en el área rural consume agua sin
ningún tratamiento y desconoce el riesgo al
que está expuesto. Es necesario desarrollar
estudios piloto en forma permanente y sostenida hasta lograr una solución definitiva
que pueda ser recomendada para su implementación en los programas nacionales de
remoción de arsénico en el agua de bebida.
15. The World Health Organization normative roles in mitigating health impacts
of arsenic in South East Asia
Deoraj Caussy
Department of Sustainable Development and
Healthy Environment, Department of Evidence
for Information and Policy, World Health Organization, Office of the South East Asia,
World Health House, Ring Road, New Delhi
110 002, India; [email protected]
Ground water contamination, in excess of
the World Health Organization (WHO)
guideline value of 0.01 mg L-1, has been
observed in many parts of the world including India, Bangladesh, Thailand, Myanmar,
Nepal, China, Taiwan and Vietnam among
others. In the South East Asia Region of
WHO, it is currently estimated that about
40 million persons may have been exposed
to contaminated ground water at various
concentrations of arsenic and almost a
quarter of a million exposed subjects are
already showing overt symptoms of chronic
arsenic poisoning. A review of the epidemiological data shows that there is a need for
internationally accepted criteria based on
evidence in the following areas: Exposure
assessment, case-definition and case management. This paper reviews the existing
epidemiological evidence for standard case
definition and management and presents
WHO strategic goals to meet these objectives. Data will be presented on the formulation and validation of standard regional protocol for case definition and case management. Other mitigation strategies including
applied research and community empowerment will also be presented.
16. Microbial volatilization of arsenic
Čerňanský S, Urík M, Ševc J1, Aranyosiová M2
1
Institute of Geology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina G, 842 15, Bratislava, Slovakia,
[email protected]
2
International Laser Center, Bratislava, Slovakia
Microorganisms have evolved diverse
strategies to overcome the toxic effects of
arsenic including microbial volatilization
through biomethylation and bioreduction.
The biological volatilization may be possibly
applied as method for arsenic removal from
contaminated localities. Microscopic filamentous fungi participate in this process as a
part of microbial community. Because of
their low nutrition demand, adaptability,
high intensity and diversity of metabolism
represent dominant biopotential for environment, which is realized in effecting of
transformation and mobility of arsenic.
Our studies have shown that the efficiency of
arsenic removal is influenced by temperature, pH value, presence of oxygen, bioavailability and concentration of arsenic, and
dominant species of filamentous fungi. For
quantification of arsenic removal and identification of arsenic metabolites in vitro the
cultivation system of different fungi
(Neosartorya fischeri, Aspergillus clavatus,
20
A. niger, Talaromyces wortmanii, T. flavus,
T. viride, Penicillium glabrum) and cultivation media enriched by desired amount of
arsenic (0,25 – 15 mg) was prepared. Fungal strains were originally isolated from
sediments from locality Pezinok – Kolársky
vrch (Slovakia) that is contaminated with
arsenic. Total arsenic concentrations of
sediments were 363-1650 mg kg-1. After a
desired time of cultivation (10, 30 and 60
days) under different conditions (pH value,
temperature) the total arsenic in cultivation
medium and mycelium was measured using
Hydride Generation Atomic Absorption
Spectrometry (HG AAS). The removal of
arsenic from cultivation system through
microbial volatilization varied between 10
– 70% of the initial amount of arsenic depending on cultivation conditions and fungal species.
For detailed chemical analysis of biological
samples (mycelia) with focus on specific
arsenic metabolites was used Secondary
Ion Mass Spectrometry (SIMS), an analytical method based on the time of flight principle. Instrument ION-TOF, SIMS IV with
unique parameters (spatial resolution 100
nm, mass resolution > 9000 m/Dm) was
used in cooperation with International Laser Center in Bratislava.
Volatile arsenicals have been identified
during a cultivation period from myceliar
head gas in cultivation system by using
sorption tubes Anasorb CSC (USA).
17. Enriched arsenic precipitates obtained from diluted industrial solutions
Ciminelli, Virgínia1, Caldeira, Cláudia Lima1;
Lara, Michelle Caetano1
1
Dept. of Metallurgical and Materials Engineering, UFMG, Rua Espírito Santo, 35, 30160-030
Belo Horizonte, Brazil;
[email protected]
[email protected]
Arsenic is a frequent toxic element released
during processing of sulfide ores. The treat-
ment of As-containing solutions involves
As(III) oxidation, followed by fixation of the
resulting As(V) in a solid phase. The most
common residues are the crystalline ferric
arsenates (e.g., scorodite, FeAsO4.2H2O)
produced in the hydrothermal processing of
refractory gold ores, or the arsenical ferrihydrites formed by precipitation of arsenic at
moderate temperatures. The latter involves a
neutralization of arsenic-rich acidic solutions
and generates large volumes of ferric hydroxide/gypsum sludge (e.g., 3-6% As).
Arsenic immobilization by scorodite precipitation under ambient pressure has been proposed as an alternative to the ferrihydrite
process but the studies have been mostly
limited to relatively concentrated solutions
(10 g As L-1) and batch systems. The present
work investigated the removal of arsenic
from dilute solutions (1 g L-1 As) produced
in the washing tower of the gas released in
the roasting of a refractory gold ore. It was
demonstrated that industrial solutions with
low arsenic concentrations (1.1 – 0.1 g L-1)
could be treated in one stage of scorodite
precipitation under ambient pressure conditions, with a removal in a range of 80.5 to
94.6%. Precipitation was carried out at 95°C.
In order to reach a molar Fe/As ratio of 1,
required for scorodite precipitation, iron (II)
sulfate was added, followed by As(III) and
Fe(II) oxidation with H2O2. In order to control supersaturation and to avoid homogeneous nucleation that yields amorphous ferric
arsenate pH was adjusted according to the
initial arsenic concentration. The removal
increased with the increase of the scorodite
seed concentration and became approximately constant (85-88%) in a range of 20 to
80 g L-1 of seeds. It was shown that a surface
area higher than 270 m2 g-1 As in solution
was necessary to promote an arsenic removal
of approximately 85%. Gypsum was an effective seed only in concentrated arsenic
solutions (10 g L-1). A procedure to achieve
high yields of arsenic removal in continuous
system was established. Due to the low rate
of crystal growth, the recycle of seeds was
required. The precipitation was favored by
21
the excess of iron, due to the increase of
initial supersaturation obtained under these
conditions. For a Fe:As molar ratio of 2:1
and 1:1, 86% and 70% of the arsenic was
removed from the solution, respectively.
The TCLP tests suggested that ageing plays
an important role on scorodite TCLP- dissolution, which decreased from 13.66 mg
As L-1 to 0.1 mg As L-1 after 8 hours of
precipitation reaction in batch tests. Scorodite was the only phase identified by microRaman and X-Ray diffraction analyses of
the precipitates. Advantages and difficulties
of the ambient-pressure scorodite precipitation with respect to industrial applications
are discussed.
18. Remoción de arsénico de aguas
naturales del valle de Camarones
mediante procesos inducidos por
radiación solar: tecnología de
descontaminación aplicable a recursos
hídricos al norte del Desierto de
Atacama, Chile
Lorena Cornejo P.1, 2, Hugo Lienqueo A.2, Jorge
Acarapi C.2, Maria J. Arenas H.2, Héctor Mansilla3, Jorge Yañez3
1
Universidad de Tarapacá, Facultad de
Ciencias, Departamento de Química, AricaChile, Casilla 7-D; [email protected].
2
Centro de Investigaciones del Hombre en el
Desierto, Universidad de Tarapacá, Arica-Chile.
3
Facultad de Ciencias Químicas, Universidad de
Concepción, Chile
Los poblados de Camarones, Esquiña e
Illapata se encuentran insertos en el valle
de Camarones al norte del Desierto de Atacama, Chile. Son beneficiados con las
aguas naturales de su única fuente de recurso hídrico el río de Camarones y diversos flujos menores de agua, como vertientes y pozos que los habitantes utilizan
para suplir sus necesidades de consumo
personal, animal y riego. Dichas aguas
presentan una contaminación natural de
Arsénico, proveniente de las zonas cordilleranas, con concentraciones en el rango de
1200 a 1300 µg L-1. Este tipo de contaminación ha afectado en forma crónica a las
poblaciones rurales asentadas en la zona
norte del país, ocasionando diversos problemas a la salud de sus habitantes. Debido a la
baja densidad poblacional que poseen estos
pueblos no es factible la utilización de tecnologías de alto costo, compleja mantención
u operación para lograr abastecer de agua
potable a estas localidades, que es el objetivo
de este trabajo.
Esta problemática ha originado un interés
creciente en el desarrollo de metodologías de
remoción útiles para disminuir niveles de
arsénico a concentraciones adecuadas para el
consumo humano y se ajuste a los niveles
máximos de arsénico permitidos, por normativas nacionales e internacionales (NCh 409 =
50 µg As L-1, OMS = 10 µg As L-1).
Este estudio comenzó con el tratamiento de
aguas sintéticas que poseían una concentración de arsénico de 500 µg L-1 y con exposición a luz artificial obteniendo resultados del 80-90% de remoción.
En seguida se trabajó el diseño, adaptación y
posterior aplicación de una metodología de
remoción simple y económica mediante ensayos de laboratorio univariados en la ciudad
de Arica. Para ello se realizaron análisis
fisicoquímicos a las muestras de aguas naturales a fin de conocer su composición, y así
trabajar con muestras sintéticas de igual
matriz. Las variables estudiadas fueron
hierro (FeSO4), citrato (C6H5Na3O7), pH,
remoción en presencia y ausencia de luz
solar y tiempo de exposición solar. El hierro
y el citrato fueron posteriormente reemplazados por materiales de uso casero accesible al poblador rural.
Finalmente, se realizaron los ensayos de
remoción “in situ”con muestras de aguas
reales del valle de Camarones. La información recopilada fue evaluada, utilizando un
software de optimización basado en métodos
de superficie de respuesta (MSR).
22
La determinación de la concentración de
arsénico remanente en solución, en todos
los casos, fue mediante espectroscopia de
absorción atómica con generación de
hidruros.
En conclusión, con la metodología propuesta se obtuvo una remoción de arsénico
mayor al 99% en terreno, presentándose
como una interesante alternativa que rinde
logros favorables en la descontaminación
del recurso hídrico para consumo de los
habitantes del Valle de Camarones.
19. Monitoring concentrations, speciation, and mobility of arsenic in geothermal sources of Ecuador´s NorthCenter Andean Region
Luis H. Cumbal, Vladimir Aguirre, Ricardo
Tipan and Carlos Chavez
Research Center Escuela Politecnica del
Ejercito, Sangolqui, Ecuador;
[email protected]
It is well known that arsenic contamination
has emerged as a worldwide problem due
to pollution of groundwater and surface
water. In several areas of Mexico and
Chile, groundwaters have been contaminated with arsenic of volcano origin. In
Ecuador, the Andean Region is surrounded
by volcanoes and geothermal waters and
some of them are used as sources of drinking water particularly in rural areas. After
petroleum contamination of a lake that is
fed by geothermal waters, its water was
characterized and arsenic concentrations
oscillated between 390 and 670 µg L-1. At
that time, it was thought that arsenic was
petroleum origin; however, our research
group recently measured arsenic in that
lake and found concentrations in the range
of 330 and 900 µg L-1. In addition, it was
found that nearby thermal waters such as El
Tambo swimming pool, Jamanco reservoir,
and Rio Tambo watershed contained between 970 and 5080 µg L-1 of arsenic.
These findings eventually indicate that
other thermal sources in Ecuador’s Andean
Region can contain this toxic element.
The objective of this study is to determine arsenic concentrations in thermal waters from the
North-Center Andean Region of Ecuador, its
chemical speciation and mobilization during the
travel towards rivers, lakes, and reservoirs. With
this information we will make a map to localize
thermal waters with concentrations above the
Ecuadorian maximum concentration level (50
µg L-1). In next stage of this study, we will investigate with local sorbents for selective arsenic removal such as zeolite or allophane rich
clay. Our research will be aimed to treat thermal
waters that are used as sources of drinking water
in rural areas.
20. Polymer-supported Fe(III) oxide
nanoparticles: A robust, reusable and
arsenic-selective sorbent
Luis H. Cumbal1 and Arup K. Sen Gupta2
1
Research Center of Escuela Politecnica del
Ejercito, Sangolqui, Ecuador
2
Department of Civil & Environmental Engineering, Lehigh University, 13 E. Packer Ave., Bethlehem, PA 18015, USA;
[email protected]
Many nanoscale inorganic particles (NIPs)
such as hydrated Fe(III) oxides, Mn(IV)
oxides, elemental Fe, magnetite, etc.; show
excellent properties conducive to selective
removal of target compounds from contaminated water bodies. Extremely high surface
area to volume ratio of these tiny particles
offers favorable kinetics for selective sorption and redox reactions. However, these
nanoparticles cannot be used in fixed-bed
columns, in-situ reactive barriers and in
similar plug flow configurations due to excessive pressure drops and poor durability.
Harnessing these NIPs within polymeric
beads offers new opportunities that are amenable to rapid implementation in the area
environmental separation and control. While
the NIPs retain their intrinsic sorption/desorption, redox, acid-base or magnetic
23
characteristics, the robust polymeric support offers excellent mechanical strength,
durability, and favorable hydraulic properties. In this investigation commercially
available cation and anion exchangers were
used as host materials for dispersing nanoscale Hydrated Fe(III) Oxides (HFO)
within the polymer phase using a simple
thermochemical technique. The resulting
polymeric/inorganic hybrid sorbent particles were subsequently used for arsenic
removal in the laboratory. The major finding of this study reveals that an anion exchanger as a support of dispersed HFO
particles offered considerably higher arsenate removal capacity compared to a cation
exchanger, all other conditions remaining
the same, the difference in selectivity and
removal capacity can be attributed to functional groups of polymeric supports. In
addition, hybrid polymers are amenable to
efficient regeneration; thus, assuring their
reuse in several sorption/desorption cycles.
On the other hand, rubbing tests demonstrate that HAIX-M particles do not lose
mechanical resistance and there is no fines
formation. Besides, sorption tests using
HAIX-M particles reveal an excellent and
simultaneous removal of arsenic and perchlorate. Consequently, HAIX-M sorbents
are media with enormous potential to be
used in community water supplies to selectively remove arsenic and other toxic
ligands.
21. Mitigation actions as a result of As
exposure investigations in Brazil
Eleonora Deschamps1, Jörg Matschullat2, Olivia
Vasconcelos3, Nilton de Oliveira Couto Silva4
1
Environmental Agency of the Minas Gerais
State - FEAM, Av. Prudente de Morais 1671,
Santa Lucia,30380-000, Belo Horizonte, Brazil;
[email protected]
2
Interdisciplinary Environmental Research
Center, TU Bergakademie Freiberg, Brennhausgasse 14, D-09599, Freiberg, Germany;
[email protected]
3
Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais,
UFMG, Brazil; olí[email protected]
4
Fundação Ezequiel Dias-FUNED, Laboratório
de Contaminantes Metálicos, Belo
Horizonte,MG,Brazil; [email protected]
Globally, millions of people are at risk from
adverse health effects of arsenic from both
acute and chronic exposure. Although most
of the As exposure comes from drinking
water, other important sources are through
food, soil and air. In Brazil, arsenic anomalies are related to geological structures, and
the additional dissipation due to centuries of
gold mining and smelting activities. Most of
the gold is associated with arsenopyrite and
to a lesser extend with pyrite. Although not
as severe and not exclusively water-related
as in Bangladesh and West Bengal, Asenrichments were recently detected in environmental and biological media in the Iron
Quadrangle, Minas Gerais state. This project
presents the mitigation actions to improve
the situation, starting with an environmental
and health perception study which led to an
environmental educational program. Next,
appropriate tailings deposits management
was started to improve control of tailings
with very high As concentrations, and to
slow down As-dissipation into the environment. Additionally, a water treatment plant
is under construction to avoid the ingestion
via As-loaded particulates in drinking water.
22. Speciation and instrumental analytical
methods as effective analytical tools for
quantification of arsenic in drinking water
Leena Deshpande and Sunil Pande
National Environmental Engineering Research
Institute, Nehru Marg, Nagpur, India;
[email protected]
Arsenic in ground water has been well recognized as a serious public health hazard in
various parts over the globe. Despite recent
developments in the quantification of arsenic
in water, the method involving generation of
24
arsine, colour development with Silver
Diethyldithiocarbamate (SDDC) and measuring colour spectrophotometrically, still
remains the method of choice in the domain
of public health laboratories.
This paper presents development of spectrophotometric method with modified glass
assembly for arsine generation. Recovery
studies of arsenic have been carried out in
presence of various cations and anions. For
validation of the method, its precision and
accuracy was determined by analyzing
synthetic water samples. Also an attempt
has been made to study substitute for pyridine, which is a hazardous solvent used in
the conventional SDDC Method.
A rapid Hydride Generation-Inductively
Coupled Plasma (HG-ICP) spectrometric
method has been developed using the ICP
spectrometer, which serves as an efficient
analytical tool for the monitoring of low
levels of arsenic in raw and potable waters.
The HG-ICP method is precise and accurate as per the international norms. This
method can be routinely adopted for the
analysis of arsenic in water samples.
23. Arsenic removal by solar oxidation in
groundwaters of Los Pereyra, Tucumán
Province, Argentina
Josefina d´Hiriart1, María Gabriela García2,
Margarita del V. Hidalgo1, Marta I. Litter3,
Miguel A. Blesa 3,4
1
Facultad de Ciencias Naturales e Instituto
Miguel Lillo, Universidad Nacional de Tucumán, Argentina
2
Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Argentina
3
Unidad de Actividad Química, Centro Atómico
Constituyentes, Comisión Nacional de Energía
Atómica
4
Universidad Nacional de San Martín,
Argentina
Shallow groundwaters from Los Pereyra,
Tucumán, are normally used for human
consumption. These waters show arsenic
concentrations that exceed the Argentine
standard requirements for drinking water.
The SORAS method (Solar Oxidation and
Removal of Arsenic) is based on the photochemical oxidation of As(III) to As(V) produced by reactive oxygen species formed in
Fe/citrate containing systems, followed by
As(V) adsorption onto the precipitated
iron(hydroxides). SORAS method provides
an economical technology to eliminate arsenic until the allowable limits.
In the present work, the efficiency of As removal by solar oxidation was assessed using
synthetic waters of known ionic composition
and shallow groundwater samples. As the
concentration of iron in the tested waters is
very low and the photooxidation of As (III) at
pH between 6 and 8 is favoured by citrate,
studies changing the sources of iron and
amounts of citrate were made. Citrate was
added in the form of lemon juice.
Tests carried out with synthetic waters of
similar composition to the study waters
showed an excellent removal, ranging between 90-60%. The efficiency of removal
was much lower in well waters, between 6030%. Results showed the influence of the
water matrix and the source of iron supply,
both factors related to the precipitation of
iron (hydr)oxides.
The influence of organic matter, HCO3- content and the initial As concentration on the
precipitation of (hydr)oxides and on the
AsO43- adsorption was assessed. An increase
in the concentration of HCO3- enhanced As
removal and Fe(III) precipitation, whereas
an increase of organic matter produced only
a slight decrease in both factors. Removal
efficiency decreased with the increase of the
initial As concentration.
The effect of different Fe sources on the
efficiency was analyzed using synthetic goethite, Fe-oxide rich sandstones and pelites,
packing wire, and nails. Removal varied
between 30 to 90% depending on the experimental conditions and the nature of the
25
iron source. Results obtained using nongalvanized packing wire are prominent, due
to the short solar exposure time and the
absence of color or turbidity in the final
treated water.
24. Concentración de arsénico total e
inorgánico en el sistema agua – alga –
trucha
Oscar Díaz Sch.1*, Nelson Núñez S.2, Estela
Recabarren G.1, Rubén Pastene O.1, Dinoraz
Vélez P.3, Rosa Montoro M.3
1
Universidad de Santiago de Chile, Casilla 40,
Correo 33, Santiago, Chile;
[email protected]
2
Programa Indígena CODELCO, Chile
3
Instituto de Agroquímica y Tecnología de
Alimentos (IATA), Valencia, España
El curso del río Loa, ubicado en la II
Región de Chile, presenta condiciones
ecológicas especiales, particularmente debido a las altas concentraciones de As en el
agua, salinidad y drenaje de los suelos. El
objetivo de este trabajo, consistió en
estudiar el comportamiento del arsénico y
su forma inorgánica más tóxica (AsIII +
AsV), en el sistema agua – alga –trucha en
un área del curso del río Loa. Muestras de
agua del río Loa, hábitat natural del alga
(Durvillea sp) y la trucha (Orcorhynchus
mykiss), fueron recolectadas en el mes de
noviembre del 2000 y 2001, en una cantidad suficiente para asegurar la confiabilidad de los resultados. Las muestras de agua
(500 mL en botellas de vidrio) y del alga
fueron obtenidas desde 5 lugares del curso
del río. Cinco ejemplares de trucha fueron
recolectados desde el río mediante red de
captura y luego cada organismo fue eviscerado y separada la cabeza, tronco y cola.
Todo el material biológico fue lavado con
agua destilada, envasado en bolsas de polietileno y congelado (-20°C) hasta ser
liofilizado. La concentración de As en el
agua fue medida directamente mediante
espectrofotometría de absorción atómica
por generación de hidruros (EAA-GH). La
determinación de arsénico total (AsT) en las
muestras liofilizadas (0.25 g) se realizó mediante mineralización por vía seca y
medición del analito mediante EAA – GH y
flujo de inyección (EAA – GH – FI). La
concentración de arsénico inorgánico (AsI),
fue determinada a través de digestión ácida,
su posterior extracción (CHCl3, 10 mL) y
cuantificación a través de EAA – GH – FI.
Altas concentraciones de As en el agua resultaron en las muestras recolectadas tanto
en noviembre del 2000 (0.07 – 0.28 mg L-1)
como en noviembre del 2001 (0.05 – 0.92
mg L-1) dependiendo del lugar de recolección. En el alga recolectada en noviembre de
2000 se encontró concentraciones de AsT
(54.02 – 98.03 µg g-1 b.s.) y AsI (41.53 –
100.55 µg g-1 b.s.), mientras que las obtenidas en noviembre de 2001 fueron 64.74 –
86.43 µg AsT g-1 b.s. y 36.90 – 59.70 µg AsI
g-1 b.s.. Altos valores del factor de bioacumulación de AsT en el alga (86 – 1281) y de
AsI (42 – 1004) fueron determinados, así
como el porcentaje de AsI, respecto al AsT,
fluctuó entre 46 – 103%. Se observó que las
concentraciones de AsT y AsI, dependen de
las respectivas concentraciones existentes en
el agua. Los niveles de AsT y AsI en la
trucha, fueron mayores en el tronco (16.02
µg AsT g-1 y 2.40 µg AsI g-1 b.s.), observándose que el AsI representa sólo el 15% del
total, a diferencia de lo que se apreció en el
alga. Se concluye que existe transferencia
del metaloide, del agua al alga y la trucha, no
evidenciándose tal situación entre el alga y la
trucha, posiblemente debido a que no existe
una relación trófica entre ambos.
26
25. Sodium arsenite impairs insulin secretion and transcription in pancreatic
β-Cells
Andrea Díaz-Villaseñor1, M. Carmen SánchezSoto2, Mariano E. Cebrián3, Patricia OstroskyWegman1 and Marcia Hiriart2
1
Department of Genomic Medicine and Environmental Toxicology, Instituto de Investigaciones Biomédicas;
[email protected]
2
Department of Biophysics, Instituto de
Fisiología Celular, Universidad Nacional
Autónoma de México.
3
Section of Environmental Toxicology, CINVESTAV, IPN, Mexico City, México
Chronic arsenic exposure by drinking water
has been epidemiologically associated with
several complex diseases and recently with
type 2 diabetes. In the present study we analyzed the impairment of insulin secretion in
single adult rat pancreatic β-cells treated
with sodium arsenite. Insulin secretion was
evaluated in vitro in a subchronic exposure
model during 72 and 144 h in the presence
of 1 and 5 µM sodium arsenite, in which cell
viability was not significantly affected.
Basal insulin secretion was not modified
with 72 h treatment, but was reduced with 5
µM sodium arsenite for 144 h. Glucosestimulated insulin secretion decreased in a
dose-dependent manner in such a way that
cells were not longer able to distinguish
between different glucose concentrations.
We further demonstrated that 5 µM sodium
arsenite can reduce insulin mRNA expression. Our data indicate that by impairing
pancreatic β-cell functions arsenic might
contribute to the development of type 2 diabetes.
26. Characterization of Fe-treated clays
and zeolites as effective As sorbents
B. Doušová1, T. Grygar2, A. Martaus1, D.
Koloušek1, L. Fuitová1, & V. Machovič1
1
Institute of Chemical Technology in Prague,
Technická 5, CZ-166 28 Prague 6;
[email protected]
2
Institute of Inorganic Chemistry AS, CZ-250 68 Řež
Adsorption of arsenic from aqueous environment on clay surfaces becomes more and
more important for economic reasons. Most
of the considered natural alumosilicates belong to low-cost and environmentally acceptable materials.
Two methods using FeII and FeIII salts were
applied to the alumosilicate pre-treatment to
improve their sorption efficiency to AsV and
AsIII species. In the first case three samples
concerning natural kaoline from the Merkur
quarry, Czech Republic, calcined at 550 °C
for 3 hours, raw clinoptiolite-rich tuff from
the Nizne Hrabovce deposit, Slovakia, and
zeolite P prepared from fly ashes were exposed to concentrated solution of FeII (0.6 M
FeSO4·7H2O) for 24 hours. Within that process, Fe2+ ions are oxidized to Fe3+ ions and the
mineral surface is covered with FeIII (oxidohydr)oxides whose high affinity for the AsV
adsorption is well known. In all investigated
systems the efficiency of AsV sorption increased significantly after the FeII treatment,
i.e. from about 15% to more than 90%.
In the second procedure, the sorbents were
prepared from raw bentonite obtained from a
mineral deposit in Cerny Vrch, Czech Republic. The bentonite was pre-treated with
solutions of FeIII (0.025 M Fe(NO3)3·9H2O,
10 min; sample a) and partly hydrolyzed
Fe(NO3)3·9H2O (0.025 M Fe(NO3)3·9H2O
0.05 M NaOH, overnight; sample b). The
sorption efficiency of FeIII-treated bentonite
to AsV increased from ~16 % in original
bentonite to ~78% (sample a, treated bentonite containing Fe3+ in cation exchangeable
positions) and to ~95% (treated bentonite
with Fe3+ in cation exchangeable positions
and in ferrihydrite).
The treatment of clays and zeolites by Fe is a
very simple method opening new possibilities in effective and cheap decontamination
of As-polluted aqueous systems. The indi-
27
vidual Fe species in the sorbents, namely
Fe3+ ions in cation exchangeable positions
and in hydrous ferric oxides were identified
by voltammetry of microparticles, diffuse
reflectance electronic spectroscopy, hightemperature X-ray diffraction, and chemical extraction by Ni-edta complex, i.e. by
novel methods, which are specific and sufficiently sensitive to detect molecular and
oligomeric species in the sorbents. The
characterization of the solid phase with
above mentioned methods will permit to
identify the actual As-sorbing species and
to tailor the sorbents with the optimal sorption properties.
27. Two-step in situ decontamination of
mining water enriched with As and Fe
B. Doušová, T. Bruha, A. Martaus, D.
Koloušek, R. Pažout, V. Machovič,
Institute of Chemical Technology in Prague,
Technická 5, CZ-166 28 Prague 6;
[email protected]
The suggested method enables the effective
removal of arsenic from strongly contaminated mining water, resulting from former
ore mining activity at Kutna Hora, central
Bohemia. The average chemical composition of mining water is in Table 1.
Table 1: Average composition of the raw
mining water from Kaňk locality
Compound
Fe
Zn
Cu
As
Mn
Cd
SO42Insoluble comp.
pH
Concentration
[g L-1]
5.752
1.589
2.7x10-5
0.054
0.166
2.27x10-4
17.665
0.295
3.5 - 4.1
The two-step process includes partial precipitation of contaminated water with a
small amount of alkaline agent. In the first
step the raw water is partially precipitated
with a defined amount of alkaline agent
(NaOH, Na2CO3 or Ca(OH)2) to pH value ~
5.0. The precipitation ran under the summary
equation:
2Fe2+ + O2 + 5OH- + H3O+ = 2FeO(OH) +
4H2O
(I)
During the first precipitation more than 90%
of presented arsenic is adsorbed as AsV on
the iron oxihydr(oxides) surface immediately, forming the inner-sphere complexes.
About 30 – 40% of precipitated iron enables
the quantitative removal of arsenic from
mining water. The “arsenic“ mass from the
first step is than separated by decantation
and/or filtration.
The final treatment of mining water runs in
the second step. The liquid residue after the
first step is precipitated with lime Ca(OH)2
to the pH value ~ 8.5. While arsenic was
substantially removed by the first precipitation, the other components including residual
iron, manganese, zinc and sulfates are precipitated quantitatively during the second
step. The mass of the second precipitate
depends strongly on the amount of alkaline
agent used in the second step. The first step
– second step precipitate ratio varies about
1:4. The higher concentration of sulfates in
the final treated water relates to the application of sodium alkalies in the first step. The
water solubilities of NaOH and Na2CO3 are
substantially higher in comparison with
Ca(OH)2 solubility.
The study of AsV - Fe - SO42- changes in
relation to the pH value enables to estimate
the optimal conditions of the process, i.e. to
produce the minimal mass of toxic precipitate while keeping ecological limits of
treated water. The two step decontamination
of arsenic enriched mining water improves
ecological and economical aspects of the
current technology.
28
28. Subchronic exposure to fluoride
modifies the arsenic metabolism and
renal oxidative damage in mice
complex, that can reduce the bioavailability
and increase the half life time in the organism for both elements.
Maribel Espinosa, Eliud A. García-Montalvo,
Olga L. Valenzuela and Luz M. Del Razo
The subchronic exposure to iAs or F- caused
oxidative stress, the exposure to both elements caused increase levels of renal GSH.
Nevertheless, in the As-F co-exposure GSH
concentrations were less than those caused
by the single exposure to each xenobiotic.
Besides this, the renal TBARS was higher in
the iAs exposure group, whereas in the exposure to F- group the renal TBARS was
increase only at the second week of exposure; this effect was similar in the coexposed group to As-F-.
Toxicology, Cinvestav-IPN, Mexico City
Inorganic arsenic (iAs) and fluoride (F-) are
ubiquitous elements. Their co-exposure is
frequent in several endemic areas due to the
natural contamination of well water supplies destined for the human consumption.
In Mexico and other areas; has been reported that the co-exposure of these two
elements in high concentrations in the water can cause typical toxic effects of arsenicism and endemic fluorosis.
The aim of this study was to evaluate the
oxidative stress of the repeated co-exposure
to arsenite (As3+) and F- in renal tissue of
female C57BL/6 mice, which were divided
in four groups and exposed daily via gavage during 6 weeks with: a) water (control
group); b) 3 mg As3+ kg-1 day-1 of sodium
arsenite, c) 10 mg F- kg-1 day-1 of sodium
fluoride, and d) both As3+ and F-, (3 mg
As3+ kg-1 day-1 and 10 mg F- kg-1 day-1),
respectively. Urine samples were collected
every two weeks (2, 4 and 6 weeks) and
levels of F- and the trivalent and pentavalent arsenical species were performed. Furthermore, at the end of exposure the arsenical species (AsIII+V, MAsIII+V, DMAsIII+V)
were determined in kidney homogenate.
Considering the pro-oxidants antecedents
associated to the exposure with iAs and F-,
oxidative stress biomarkers at renal level
were evaluated such as glutathione (GSH)
concentrations, also the renal oxidative
damage was evaluated through lipid peroxidation (TBARS).
The results showed that the As3+-F- coexposure modified the pattern of arsenical
species excreted and modified the urinary
excretion of the F-. These results suggesting
an interaction between the As3+ and the Fthrough the possible formation of As-F
In future studies to evaluate the biotransformation and the toxic effects caused by iAs
exposure, the co-exposure to F- need to be
considered.
29. Evaluación de riesgo toxicológico
asociado a la ingesta de aguas
naturalmente contaminadas con arsénico
y otros oligoelementos tóxicos en La Puna,
Argentina
Silvia S. Farías1, Graciela Bovi Mitre2, Rebeca I.
Ponce2, María E. Ávila Carrera2, Gladi Bianco de
Salas1, Roberto E. Servant1
1
Atómica. Av. Gral. Paz 1499. B1650KNA-San
Martín. Pcia. de Buenos Aires. Argentina
2
Grupo InQA- Investigación Química Aplicada.
Facultad de Ingeniería. Universidad Nacional de
Jujuy. Gorriti 237-(4600) S. S. de Jujuy- Pcia de
Jujuy. Argentina.
El presente trabajo fue realizado entre mayo
de 2001 y julio de 2003 en el Noroeste de la
República Argentina. A partir de imágenes
satelitales, se estudió un área de 20 000 km2
en la zona de La Puna salto- jujeña y otra de
unos 10 000 km2 en la zona de los valles y
sierras sub- andinas, en las que se realizó un
muestreo bajo normas de calidad, para
comparar los tenores de As, B, V y F- y
estimar el riesgo asociado a su ingesta.
29
Las muestras, provenientes de fuentes superficiales y subterráneas fueron analizadas
mediante ICP-OES, para determinar As, B
y V y cromatografía iónica para evaluar F-.
En la Puna se detectaron valores de hasta 2
mg/L As, mientras que en los valles las
concentraciones de As nunca fueron mayores que el límite establecido por el Código
Alimentario Argentino (50 µg L-1 As). Las
concentraciones de B asociadas a los
máximos tenores de As treparon hasta 50
mg L-1 B, las de F- alcanzaron valores de
hasta 4 mg L-1 F-, en las muestras captadas
en La Puna, superando así los máximos
permitidos por dicha Ley (1 y 2 mg L-1,
respectivamente). Y, contrariamente a lo
descrito en estudios anteriores realizados en
Llanura Pampeana, no se ha observado
correlación entre As y V, encontrándose
concentraciones que nunca fueron mayores
que 100 µg V L-1 en las dos zonas
estudiadas.
Una vez identificada el área impactada por
estos contaminantes se evaluó la dosis de
exposición para caracterización de riesgos
no- cancerígenos para la población expuesta, discriminando entre adultos y niños,
que por sus condiciones físicas y su menor
peso corporal, constituyen el grupo de
mayor riesgo.
Los resultados informados se discuten en
relación con una estimación preliminar de
riesgo toxicológico al que están expuestos
los grupos poblacionales estudiados considerando únicamente la ingesta de agua
como vía de exposición para estos contaminantes críticos, especialmente el arsénico.
Para ese elemento, en la zona de los valles,
los valores de dosis para adultos y niños
(0.8-2.0 µg kg-1 peso/día, respectivamente),
nunca superaron el LOAEL- mínima concentración con la que se observan efectos
tóxicos (LOAEL para riesgo no- cancerígeno * = 2.6 µg kg-1 peso corporal /
día), mientras que en la zona de La Puna se
determinaron valores de estas dosis com-
prendidas entre 1 y 30 µg kg-1 peso/día, para
adultos, y entre 4 y 80 µg kg-1 peso/ día, para
el caso de niños, valores que podrían llegar a
superar en algunos casos el LOAEL para
riesgo cancerígeno (15 µg kg-1 peso/día).
Se propone la realización de un mapa de
riesgo para estos elementos, la evaluación de
los pobladores por médicos dermatólogos y
psicólogos que efectúen pruebas neuroconductuales, especialmente en niños, así como
también la implementación de un sistema de
abatimiento sencillo y económico aplicable a
poblaciones rurales dispersas.
(*riesgo no-cancerígeno, relacionado con
lesiones dérmicas y efectos neurológicos)
30. Arsénico y otros elementos tóxicos en
aguas termales, lagos, vertientes y aguas
de consumo, en las cercanías del volcán
Copahue, Argentina
Ana María Fazio1, Silvia S. Farías2, Alberto T.
Caselli1, Mariano Agusto1
1
Departamento Ciencias Geológicas. Facultad de
Ciencias Exactas y Naturales, Universidad de
Buenos Aires. Ciudad Universitaria, Pabellón
2.1428EHA Buenos Aires, Argentina
2
Atómica. Av. Gral. Paz 1499. B1650KNA- San
Martín. Pcia. de Buenos Aires. Argentina
El Copahue, es un volcán activo de 2297
metros de altura, localizado en la parte
oriental de la zona volcánica de Los Andes,
al Sur-Oeste de la República Argentina. La
presencia de un lago ácido en el cráter,
fuentes termales ácidas de elevada temperatura y un campo geotermal, son las
expresiones superficiales de un sistema
hidrotermal volcano-magmático. La principal fuente termal, de características ácidas y
elevada temperatura emerge alrededor de
100 metros por debajo del lago del cráter y
alimenta al llamado “Río Agrio”, que
descarga 12 kilómetros más abajo en el Lago
Caviahue, un espejo de agua ácida de origen
glacial.
30
Desde el invierno de 2003 se han venido
realizando muestreos estacionales, bajo
normas de calidad, para observar las
variaciones en las concentraciones de
aniones y de cationes presentes en las aguas
bajo estudio, de forma de poder establecer
tácticas de monitoreo.
ellos como “curativas”; y a prohibir su utilización en el caso que los tenores de As y
otros elementos tóxicos, superen los valores
establecidos por la legislación vigente al respecto.
Las muestras, provenientes de fuentes superficiales y subterráneas fueron analizadas
mediante espectroscopia de emisiónplasma inductivo de argón para determinar
As, Al, B, Ba, Be, Bi, Cd, Cr, Co, Cu, Fe,
La, Mn, Mo, Ni, P, Pb, Sb, Se, Sr, Ti, V, Y
y Zn; mediante cromatografía iónica para
evaluar F-, Cl-, NO3-, SO4-, y se empleó
absorción atómica en llama para cuantificar
Na, K, Ca y Mg.
31. Arsenic removal using ferric chloride
and direct filtration
Los tenores de As observados superaron en
muchos casos valores de 5 mg As mL-1,
para muestras captadas durante el invierno.
Se hallaron concentraciones significativamente menores de este elemento, para
muestreos realizados en otras épocas del
año. Asimismo, se observaron variaciones
estacionales para la mayoría de los otros
elementos estudiados, muchos de ellos con
niveles de toxicidad comparables al del As.
Arsenic is a carcinogenic metalloid that is
currently regulated in drinking water. The
levels of arsenic in finished water in an existing water treatment plant are exceeding
the current regulation of 10 µg L-1. One of
the available technologies for arsenic removal from groundwater is adsorption onto
coagulated flocs and in this field, ferric chloride is the most commonly used coagulant
for arsenic removal. This research work was
conducted to explore a suitable conventional
treatment technology for arsenic removal
from given groundwater in order to reduce
the filtrate arsenic concentration to less than
10 µg L-1.
Una vez identificado el patrón de variación
de las concentraciones de los diferentes
elementos a lo largo del año se procedió a
establecer una frecuencia de muestreo para
monitorear las aguas de consumo, y las
aguas termales a las que están expuestos
miles de turistas que acuden cada año, a
este Centro Termal, durante períodos semanales o quincenales, en busca de alivio
para el caso de patologías reumáticas y
óseas, de terapias anti- estrés ó simplemente de merecido descanso y relajación.
Los resultados obtenidos se han informado a
las autoridades sanitarias para que alerten a
los turistas sobre los peligros inherentes a la
exposición prolongada a aguas naturalmente
muy contaminadas, durante los baños termales que practican diariamente y por largos
períodos de tiempo; a evitar la ingesta de
esas aguas, consideradas por muchos de
R. G. Fernández1, B. Petrusevski2
1
Centro de Ingeniería Sanitaria - Facultad de
Ingeniería, Universidad Nacional de Rosario.
Riobamba 245 bis – 2000 Rosario – Argentina;
[email protected]
2
UNESCO-IHE - Institute for Water Education.
PO Box 3015 – NL-2601 DA Delft – The
Netherlands; [email protected]
Bench scale jar test experiments and pilotscale investigations were carried out to
evaluate and improve the coagulation / flocculation process for arsenic removal using
ferric chloride. Model water that represented
the water from the existing water treatment
plant was used to investigate the effects of
different conditions of pH, coagulant doses,
arsenic speciation, initial arsenic concentration, temperature, and flocculation conditions on the arsenic removal efficiency by
coagulation / flocculation process. Based on
these bench scale experiments, a direct filtration technique to separate the formed flocs
was considered as the most suitable floc
31
separation system to be applied after coagulation/flocculation process. A direct filtration pilot plant was operated to evaluate the
efficiency of arsenic removal.
The results of series of jar test experiments
showed that As(V) could be completely
removed with iron doses higher than 2 mg L1
for filtered samples and at pH value about
7.0. The lower efficiencies obtained for unfiltered samples indicate that settling mechanisms are not effective enough to ensure
complete removal of As(V), even when
using very high doses of coagulant. In agreement with the results of previous studies, it
was found that As removal efficiency increased with the coagulant dose. Additionally it was also observed that under the
given conditions As(III) removal efficiency
was much lower (up to 60%) compared to
As(V) removal efficiency (90 - 100%).
Direct filtration with iron doses of 2 mg L-1
at pH value about 7.0, could reduce As(V)
levels from 50 to 4 µg L-1 or less without
any risk of iron or turbidity increasing in
the filtered water within a reasonable filterrun length.
Direct filtration using ferric chloride as
coagulant, could be an appropriate technology to reduce arsenic levels below 10 µg L-1
for the given groundwater.
32. Rapid, clean and low-cost assessment
of inorganic arsenic in the mussel Mytilus
Galloprovincialis Lmk. by visible and
near-infrared spectroscopy
Rafael Font1, Dinoraz Vélez2, Mercedes Del
Río-Celestino3, Antonio De Haro-Bailón1, Rosa
Montoro2
1
Instituto de Agricultura Sostenible (CSIC).
Alameda del Obispo s/n. 14080, Córdoba, Spain
2
Instituto de Agroquímica y Tecnología de
Alimentos (CSIC), Apartado 73, 46100, Burjassot (Valencia), Spain
3
CIFA, Junta de Andalucía, Apdo. 4240, 14080
Córdoba, Spain
M. galloprovincialis Lmk. represents an
important resource for fishery in Spain. This
production places Spain as the second producer of mussel of the world, after China. In
addition, Spanish export trade for mussel is
increasing quickly, mainly in Europe, where
countries as Belgium imports over 12000 kg
of M. galloprovincialis every day.
Among the metals and metalloids present in
the environment, arsenic (As) stands out
because of its toxicological potential. Arsenic is found in food in various chemical
forms that differ in their degree of toxicity
and pathologies associated with it. The most
toxic forms of As are the inorganic ones
(iAs), i.e., As(III) and As(V), which are considered human carcinogens.
Thus, concern for food safety in relation to
iAs occurrence in foods currently calls for
exhaustive controls of these molecular forms
in a variety of food products. The standard
methodologies for iAs determination offer a
high level of precision but at the same time
show some handicaps, such as high cost of
analysis, slowness of operation, destruction
of the sample, and use of hazardous chemicals. The availability of fast methodologies
to quantify iAs levels in different kinds of
foods would contribute to the drawing up of
legislation to guarantee the healthiness of
foods with respect to this metalloid.
One approach to the consecution of such
objectives is made through the use of Visible-Near-Infrared Spectroscopy (VIS-NIRS).
VIS-NIRS is a valuable technique that offers
speed and low cost of analysis, and also the
sample is analyzed without using chemicals.
The spectral information obtained from samples can be used for prediction of the iAs,
once appropriate calibration equations have
been prepared from sets of samples analyzed
by both VIS-NIRS and conventional analytical techniques.
We present in this work the potential of VISNIRS to predict iAs in different matrices of
animal and plant origin. Mathematical models (calibration equations) were developed
32
over the spectral data jointly with the iAs
concentrations in the samples, by using
Modified Partial Least Squares (PLSm)
regression. On the basis of the coefficients
of determination (R2) shown by the equations in the validation, and also of the standard deviation to standard error of prediction in the validation (RPD), the equations
obtained displayed a high predictive ability
to determine iAs in such matrices. Our
results suggest that both, the VIS (chomophores) and NIR (X-H, where X= C, O, N)
regions of the spectrum from the matrices
used to conduct this work, contain relevant
information that can be related to the iAs
concentration in the samples. This pioneering use of VIS-NIRS to predict the iAs
content in biological matrices represents an
important saving in time and cost of analysis.
33. Intermediate to high levels of arsenic
and fluoride in deep geothermal aquifers
from the northwestern Chacopampean
Plain, Argentina
María Gabriela García1, César Moreno2, Diego
Sebastián Fernández3, María Cristina Galindo2
Ondra Sracek4 and Margarita del Valle Hidalgo2
1
Centro de Investigaciones Geoquímicas y de
Procesos de la Superficie. FCEFyN. Universidad Nacional de Córdoba
2
Centro de Investigaciones y Transferencia en
Química Aplicada. Tucumán. FCN e IML.
Universidad Nacional de Tucumán. Tucumán,
Argentina. Córdoba, Argentina
3
Servicio Geológico Minero Argentino, Delegación Tucumán
4
Dep. of Geological Sciences, Faculty of Science, Masaryk University, Brno, Czech Republic
High levels of natural occurring arsenic and
fluoride in groundwaters from the Chacopampean plain have been assigned to the
presence of volcanic shards spread within
the loess matrix. The primary source of
these elements has not been determined yet
but there is almost a clear understanding
about the mechanisms that promote their
mobilization in the aquifers. Geochemical
evidence suggests that, after being released
into groundwater, the concentration of arsenic in solution is controlled by pH. Arsenic
is preferentially scavenged by adsorption on
Fe (hydr)oxide coatings under acidic to neutral pH conditions. The concentration of
fluoride depends on the fluorite solubility
and also on pH-dependent adsorption with
adsorption minimum at high pH values.
In the province of Tucumán, the loessic layer
is restricted to the first 30 meters of the Quaternary sequence. As a consequence, most
shallow groundwater is contaminated by
high levels of As and F-. Groundwater in
deep confined aquifers is considered to be
suitable for human consumption. However,
in the southern part of the province several
wells show from intermediate to high concentrations of As (between 10 to 79 µg L-1)
and high concentrations of F- (between 0.6
and 6.0 mg L-1). These wells that penetrate
saturated layers as deep as 500 mbs, show
ground water temperatures above the annual
average in the region. Some authors proposed that the heat is supplied from a basaltic layer located 7000 mbs.
The geochemistry of As and F- in deep aquifers shows certain characteristics that are not
completely coincident with those described
in the rest of the Chacopampean plain.
Unlike in shallow groundwaters, the concentrations of As increase with increasing depth
and temperature. The same trend is observed
for F-, but the relation with depth is not such
clear. Furthermore, As shows direct linear
correlation with sulphate and reverse correlation with bicarbonate and calcium. F- is
poorly correlated with arsenic, but highly
correlated with chloride and sodium. It also
shows reverse correlation with calcium.
Concentrations of F- increase at increasing
pH and decreasing Eh, but this trend is less
evident for As.
The primary source of As and F- in the deep
confined aquifers can be associated with
volcanic Tertiary sediments that are sup-
33
posed to be in the deepest part of the sedimentary sequence. The up-flow of geothermal fluids through structural conduits is
considered negligible because ground water
chemistry matches those of volcanic sediments. The mobilization of As does not
seem to be controlled only by the pH, but
also by other factors such as the presence of
As-rich primary source sediments. The
concentration of F- is not affected by the
precipitation of fluorite as its supersaturation is never reached due the removal of
Ca2+ by the precipitation of calcite and/or
cation exchange.
34. Lipoperoxidative damage, nerve conduction and histological characteristics
of sensory sural nerves of rats exposed to
arsenite
Erika García-Chavéz1; Bertha Segura2; Horacio
Merchant3; Luz C. Sánchez-Peña1; A. Barrera1,
Jose C. Guadarrama4, Ismael Jiménez4 and Luz
M. Del Razo1
1
Toxicology, Cinvestav-IPN, Mexico. 2 FESIztacala, UNAM, Mexico,3IIB-UNAM, Mexico,4Physiol., Biophys. & Neurosci., CinvestavIPN, Mexico
Although the remarkable interest on toxicological properties of inorganic arsenic
(iAs), it has limited amount of information
on the capacity of this metalloid to interact
and cause structural and functional alterations of the nervous system. Previous studies have demonstrated that humans exposed
to iAs affect the central nervous system and
can produce peripheral neurotoxicity. Generation of reactive oxygen species (ROS) is
the major mechanism by which arsenic
exerts its toxicity in a variety of tissues.
ROS has been demonstrated in rat brain
exposed to iAs, although their role in the
peripheral nervous system is not fully established. In addition, the adverse effects of
arsenical exposure have not been related to
the presence of methylated arsenic species
(MAs and DMAs) formed during the iAs
metabolism and distributed in nervous sys-
tem, which could be in some extent responsible for the neurotoxic alterations reported.
Our aim was to assess the relation of the
distribution of iAs and its metabolites, its
oxidative damage, nerve conduction and
histological characteristics of the peripheral
sural nervous of rat subchronic exposure to
arsenite. Wistar male rats (200 g body
weight) received sodium arsenite (10 mg kg-1
bw/day, gavage, for 30 days). Thiobarbituric
acid-reactive substances (TBARS) and distribution of iAs and its metabolite in sural
nerve were evaluated at the end of 30 days of
exposure. Sural nerve conduction studies
were performed for measurement the compound action potentials and transversal sections using standard electrophysiological and
histological techniques. The results revealed
oxidative damage in sural nerve as compared
from control group (p<0.0001). Dimethyl
arsenic was the predominant metabolite of
iAs (∼95%) in peripheral nervous tissue.
Meanwhile, the compound action potential
evoked in exposed nerves showed a considerable reduction area (~18%; p<0.05) and
conduction velocity (~18%; p<0.05). These
electrophysiological finding were well supported by the histological observation of
reduction in axon diameter (~34.8%;
p<0.01) and myelin sheath thickness of axons (~40%; p<0.01), as compared with those
of control nerves.
Our results may indicate that the high concentration of DMA in rat peripheral nerves
causes demyelinating and axonal changes
altering the generation and propagation of
action potentials in peripheral nerves and
those effects could result in decreased
transmission of sensory information from
peripheral receptors to the spinal cord.
34
35. Arsenite biotransformation in mice
feed with selenium deficient diet and
exposure to arsenite
Eliud A. García-Montalvo, Olga L.Valenzuela,
Araceli Hernández-Zavala, Luz M. Del Razo
Cinvestav-IPN, Toxicology; Mexico City,
Mexico
Arsenic (As) is a widespread environmental
toxicant in several parts of the world, the
main way of exposure is through the drinking water or industrial emissions. In humans, like in most mammalian species,
inorganic arsenic (iAs) is methylated to
methylarsonic acid (MMAV) by AsIIImethyltransferase (AS3MT) using Sadenosylmethionine (SAM) as a methyl
group donor. The MMAV through alternative reductions form methylarsonous acid
(MMAIII) which is methylated by AS3MT
and SAM producing dimethylarsinic
(DMAV) which again by alternative reduction produce dimethylarsinous (DMAIII).
The main mechanism of toxic action related
with the exposure to iAs and the produced
metabolites, mainly the trivalent arsenicals
species are linked with the reactive oxygen
species (ROS) who are the responsible of
the stress generation and oxidative damage.
On the other hand, selenium (Se) is an essential constituent of the antioxidant system
that allows the survival of whom in a rich
oxygen environment where the free radicals
can damage the biological molecules. Is an
essential micronutrient for humans because
it is an important component of antioxidants enzymes as glutathione peroxidase
(GPx) and thioredoxin reductase (TrxR).
Like As, Se is a metalloid which undergoes
similar metabolic conversions, the inorganic species as selenate (SeIV) and selenite
(SeVI), are reduced by glutathione (GSH) to
yield hydrogen selenide (H2Se), H2Se
serves to produce the organic selenium
compounds of interest in health and nutrition. Since the metabolic interactions between As and Se are complex and it would
represent a practical significance because
many human populations are simultaneously
exposed to As through drinking water and
different levels of Se mainly in the diet. The
aim of this study was to evaluate the biotransformation and distribution of As and
their relationship with stress oxidative events
in function of the deficient SeMet concentration in weanling female C57BL/6 mice feed
by 42 days with Se deficient diet (0.02 mg
Se kg-1) and exposed daily to 6 mg As kg-1
day-1 for 9 consecutives days. Oxidative
stress biomarkers at hepatic level were
evaluated such as GSH and GPx concentrations; also the renal oxidative damage was
evaluated through lipid peroxidation
(TBARS).
Se deficiency group had not alteration in the
urinary and liver concentration of arsenicals
comparing with diet Se sufficient (0.2 mg Se
kg-1) but, increases the urinary relative proportions of iAsIII, iAsV, MMAIII, and MMAV
accompanied by decreases in DMAIII and
DMAV. In addition, increases the relative
proportion of iAs and decreases DMA proportion in liver.
The Se deficient group exposed to arsenite
decreases the concentration of hepatic GPx.
However, this decrease was not associated to
the presence of hepatic oxidative damage
suggesting the possibility of DMA metabolite could be the responsible of oxidative
damage observed in mice exposed to arsenite
and feed with Se sufficient diet.
Se deficiency in the diet affected the arsenite
biotransformation pattern and its relation
with stress oxidative markers.
35
36. Neurotoxicity of arsenic
María E. Gonsebatt, Verónica Rodríguez, Jorge
H. Limón, Roxana Navarrete, Hielen Queriol,
Magda Giordano, Gabriel Gutiérrez Ospina y
Luz Maria Del Razo
Instituto de Investigaciones Biomédicas e Instituto de Neurobiología, UNAM, CINVESTAV,
IPN México; [email protected]
Epidemiological studies demonstrate that
inorganic arsenic exerts other adverse effects that do not involve the induction of
cancer such as injury to the peripheral and
central nervous systems. Arsenic crosses
the blood brain barrier and might accumulate in brain where it could be metabolized
to monomethyl (MMA) and dimethyl
(DMA) arsenic forms. In mammals, biomethylation by the arsenic methyltransferase (As3MT) occurs in two steps: 1) the
reduction of pentavalent species to trivalency in the presence of glutathione (GSH)
or thioredoxin and 2) the oxidative methylation whereby inorganic arsenic is converted to MMA, DMA and trimethyl
(TMAO) arsenic forms using S-adenosyl
methione (SAM) as the main methyl donor.
To investigate the possibility that arsenite
was methylated in brain, we treated mice
with different doses of sodium arsenite and
observed the generation of methylated species not only in the animals but also in
brain organotipic cultures. Arsenic is metabolized in mouse brain, mostly to DMA
in a dose related manner. Also, contrary to
what have been shown in “vitro” inhibition
of glutathione reductase, a key enzyme in
the maintenance of GSH pool, was observed only at very high doses of arsenite.
Besides the toxic effects of the accumulation of methylated arsenicals in neural tissue, both GSH and SAM are important
molecules not only in the biochemistry of
arsenic but in the physiology of the nervous
system. Thus, arsenic metabolism could
diminish the GSH pool in the central nervous system, a condition that is associated to
neurodegenerative processes such as Alz-
heimer’s, Parkinson and schizophrenia. Biotransformation of arsenic in brain could also
alter the homeostasis of SAM and its intermediate metabolites, including methionine,
choline, folate, and vitamins B6 and B12,
some of which are important substrates or
cofactors in neurotransmitter metabolism or
in the development of the CNS especially in
more susceptible individuals such as children
and older people.
37. Arsenic origin determination by geochemical modeling: Region Lagunera
aquifer system, Mexico
Carlos Gutiérrez-Ojeda
Instituto Mexicano de Tecnología del Agua,
Paseo Cuauhnáhuac 8532, Jiutepec, Morelos,
62550 México.; Tel (+52 73) 194000 ext
793/805; Fax (+52 73) 194341 / 193422
The elevated arsenic concentrations found in
the groundwater of the alluvial aquifer of the
Region Lagunera, northern Mexico, have been
attributed to several potential sources:
hydrothermal activity, use of arsenical
pesticides, mining activities and sedimentary
origin.
Arsenic concentrations range from 0.003 to
0.443 mg L-1 (mean of 0.074 mg L-1; standard deviation 0.099). Extensive areas of the
alluvial aquifer have concentrations quite
above 0.03 mg L-1, the Mexican Maximum
Contaminant Level (MCL) for drinking water. The highest concentrations are found in
the lagoonal deposits located in the northeastern part of the basin, as well as towards
the northwestern and southeastern areas.
Previous studies have showed that arsenic is
naturally occurring and its most probable
origin is due to extinct intrusive hydrothermal
activity. Geochemical modeling were used in
this work to show that under natural and
unchanged conditions, the evaporation of
surface water carried by the Nazas and
Aguanaval Rivers (0.00201 < As < 0.01766
mg L-1) could have contributed to the elevated
36
groundwater arsenic concentrations (0.003 <
As < 0.443 mg L-1) found in the lower parts
of the closed basin.
The idea was to select two water samples;
one representative of the surface water (from
reservoirs) and the other of the groundwater
of the area where elevated arsenic
concentrations have been found. Then,
artificially evaporate the surface water by
multiplying its analytic chemical data by the
chloride ratio between both samples. A
modified version of the aqueous speciation
program WATEQF was used to determine
the saturation indices of plausible minerals
(phases) of both the evaporated surface water
and the groundwater. The geochemical
program NETPATH was then used to determine the net geochemical mass-balance
reactions between the evaporated surface
water (initial water) and the groundwater
(final water).
The results show that evaporation of 51.51
liters of surface water from the Nazas River
would produce one liter of well 1387; this
would require the precipitation of calcite
(43.86 mmol) and fluorite (1.46 mmol),
dissolution of gypsum (6.60 mmol), outgassing of CO2 43.19 mmol), and an exchange
of 1 mmol of calcium (entering the aqueous
solution) per every 0.42 mmol of sodium,
2.46 mmol of potassium and 4.01 mmol of
magnesium (leaving the aqueous solution).
Salamanca. There are not alternative water
supply sources.
The local aquifer is composed by 3 permeable units, forming a multilayer aquifer system. A shallow formation, an intermediate
one, semi confined, and a deep unit, confined. The shallow water table is located 1819 m depth. The intermediate water table is
found to 35-45 m. Clay, gravel and sand
composed the shallow and intermediate aquifers, whereas volcanic material formed the
deep unit.
The arsenic concentration in the 3 units is
variable. The space distribution looks to be
controlled by a fault originated by subsidence.
A local fast recharge through the fault system
can affect the As concentration.
The deep aquifer As could be associated to
the sequence of volcanic rocks. Its groundwater is thermal. The As detected in the intermediate formation, exploited for urban
supply could be natural and anthropogenic.
Taken into account these chemical characteristics some alternatives for aquifer management are proposed.
39. Estudio del efecto de los procesos
termicos sobre la concentración de
arsénico total, arsénico inorgánico en los
productos pesqueros
C. Herrera†; O. Muñoz*†; J,M. Bastias‡;
38. Arsenic distribution in the multilayer aquifer of Salamanca, México
H. Hernández, R. Rodríguez and A. Armienta
Geophysics Institute, UNAM; Earth Sciences
Postgraduate Program UNAM, Mexico
Salamanca is located in Central Mexico,
Guanajuato state, in the Subprovince Bajio
Guanajuatense in the Physiographic Province Eje Neovolcanico. The geologic environment is defined by volcanic and sedimentary rocks from Tertiary to Recent.
Groundwater is the only water supply for
†Centro de Estudios en Ciencia y Tecnología de
Alimentos, Universidad de Santiago de Chile,
Casilla 33074, Correo 33 Santiago;
[email protected]
‡ Departamento de Ingeniería en Alimentos,
Universidad del Bío-Bío, Casilla 447, Chillán,
Chile; [email protected]
El presente estudio determinó el efecto de
los procesos térmicos utilizados en el
cocinado habitual sobre la concentración de
arsénico total, y arsénico inorgánico en cinco
especies marinas de mayor consumo en la
ciudad de Santiago (Choritos, Almejas,
Cholgas, Jurel y Congrio negro), Se
37
utilizaron cinco muestras de cada especie y
tres tratamientos (crudo, hervida y al
horno). La determinación de Arsénico total
se realizó por digestión por vía seca, En el
caso del arsénico inorgánico, se utilizó un
procedimiento de extracción por solventes,
obteniendo en todos los casos resultados
reproducibles y representativos.
Para la determinación analítica se utilizó un
Espectrofotómetro de Absorción Atómica
(AAS) Varian A 55 acoplado a generación
de hidruros.
En las muestras crudas, la mayor concentración de metales se encuentra en los bivalvos (6.18-15.19 µg g-1, base seca (bs) de
As total; 0.11-0.23 µg g-1, bs de As inorgánico), los peces obtuvieron menores contenidos de ambos metales (1.69-5.61 µg g-1,
bs de As total; 0.08-0.12 µg g-1, bs de As
inorgánico).
El Análisis de ANOVA por especie (Choritos, Almejas, Cholgas, Jurel y Congrio
negro), de los resultados obtenidos en
relación a los tres tratamientos utilizados
(crudo, hervida y al horno), tanto para arsénico total como para arsénico inorgánico,
presentaron un valor de P<0.05 indicando
que existen diferencias estadísticamente
significativas entre los tratamiento. Por lo
tanto, al someter los productos pesqueros a
procesos térmicos se producen modificaciones en el contenido de Arsénico total, las
que se atribuyen a la suma de efectos contrarios: concentración debido a la pérdida
de peso del alimento, la cual es mayor en el
caso de productos horneados, y por pérdida
del arsénico soluble debido a la eliminación
de exudados. Con respecto al arsénico inorgánico se suma el efecto de transformaciones que pueden ocurrir en las especies
orgánicas a inorgánicas.
40. Subsurface treatment of arsenic in
groundwater – laboratory scale
experiments
Holländer, H.M.*; Boochs, P.-W.*; Stummeyer,
J.**; Billib, M.*; Krüger, T.*
*
Institute of Water Resources Management, Hydrology and Agricultural Hydraulic Engineering, University of Hannover, Germany;
[email protected]
**
Federal Institute of Geosciences and Natural
Resources (BGR), Hannover, Germany
Objectives. High arsenic concentrations in
groundwater (up to 8500 µg L-1) have been
found at a military site. It should be investigated whether a subsurface groundwater
treatment (in-situ treatment) can be applied
to remove the arsenic. The procedure is
based on the injection of iron and oxygen
enriched water into the aquifer to precipitate
the arsenic together with the iron.
Methods.
Laboratory experiments were
carried out at batch reactors using natural
groundwater with high arsenic concentrations from the contaminated site. Different
iron compounds containing Fe(II), Fe(III) or
Fe0-particles have be mixed with the water
and were aerated for several hours. The detection of arsenic was separated into As(III),
As(V) and organic As.
Results. The results showed that it is impossible in this case to precipitate the arsenic
without adding additional iron (removal of
arsenic was below 2%) because the iron
which is naturally in the groundwater is too
low. Fe(II) showed the best results. The reduction of arsenic was nearly 80%. The presents of ammonium was reducing the arsenic
to only 40%. This is caused by the oxygen
demand of the nitrification process. The
precipitant Fe(III) had only a small effect in
reducing the arsenic concentration (less than
10%). Fe0-particles can be also used to reduce the arsenic. The reduction was observed of 60%.
Conclusions. The removal of arsenic by
injecting oxygen into the aquifer without an
38
additional precipitant is impossible at the
contaminated site because the natural iron
content is very low. But first laboratory
experiments showed that it is possible to
remove high arsenic concentrations with
adding additional iron as participant. Best
results were observed using Fe(II) or Fe0particles.
Further investigations will be carried out to
optimize the iron concentration and to
transfer the results to a field experiment at
the military site.
41. Effects of selenium deficiency on diabetogenic action of arsenite in rats
Jeannett A. Izquierdo-Vega1, Claudia A. SotoPeredo2, Luz C. Sánchez-Peña1, and Luz M. Del
Razo1
1
Toxicología, Cinvestav-IPN, Mexico
Sistemas Biológicos, UAM-Xochimilco, Mexico
2
Selenium (Se) is an essential trace element
for animals and humans, it play important
role in the protection against oxidative
damage. In addition, it is an insulin-like
trace mineral that regulate homeostasis of
the glucose.
Selenium deficiency is one of the factors
related to diabetes, malnutrition, low corporal weight, muscular dystrophy, rheumatoid
arthritis and diseases associated to the presence of oxidative stress. The metabolic and
toxicological interactions between arsenic
(As) and Se have been reported in many
experimental studies. It would represent a
practical significance because many human
populations are simultaneously exposed to
As through drinking water and different
levels of Se mainly in the diet. There are
recent epidemiologic studies that have associated chronic exposure to inorganic
arsenic with an increase in the prevalence
of diabetes mellitus. In a previous study,
we showed that the subchronic exposure to
arsenite in rats causes insulin resistance.
Our aim was evaluate if deficiencies of Se,
therefore, can have a detrimental effect on
insulin resistance caused by subchronical
arsenite exposure.
In the present study we evaluated the endocrine function and oxidative damage in pancreas of male Wistar rats (200 g body
weight) feed with Se deficient diet (0.02 mg
Se kg-1) and exposed to sodium arsenite at
1.7 mg kg-1 12 h by gavage for 90 consecutive days. Rats received the Se deficient diet
twenty days before the administration of first
dose of arsenite and continued for 90 days of
arsenite exposure. At the end of the treatment, glucose, insulin and glucagon concentration in serum were quantified. A simple
method to quantify insulin resistance was
assessed through the measurement of glucose and insulin (fasting glucose [mmol/L]
X fasting insulin [mU L-1]/22.5). Oxidative
stress biomarkers at pancreatic level were
evaluated such as glutathione and the activity of seleno-enzyme thioredoxin reductase
(TrxR); also the pancreatic oxidative damage
was evaluated through lipid peroxidation
(TBARS).
The insulin resistance caused by subchronic
arsenite exposure in rats feed with Se sufficient diet (0.2 mg Se kg-1) was no exacerbated in Se deficiency. Rats exposed to arsenite and fed with Se deficiency had value
of insulin resistance of 14.10 ± 5.04 vs
13.17± 4.79 obtained in Se sufficiency; these
values were significantly higher than those
of their respective Se-deficient and Sesufficient control groups (1.84± 1.35 vs
3.34± 1.19).
Independent of arsenite exposure, the Sedeficient diet caused stress and oxidative
damage in pancreas. Besides, pancreatic
oxidative damage was significantly higher in
rats subchronically exposed to arsenite with
low Se status than rats with Se adequate diet.
The changes may be related to the decreased
activity of TrxR, selenoenzyme with antioxidative functions.
Se deficiency in the diet intensifies the pancreatic oxidative damage but did not alter the
39
hiperinsulinemia caused by subchronic
arsenite exposure.
42. Occurrence, distribution and temporal variation of the concentrations of
arsenic in groundwater from Jhikorgachha Upazila, Bangladesh
M. Jakariya1*, Kazi Matin Ahmed2, M. Abul
Hasan2, Sultana Nahar2 and P. Bhattacharya3
1
Research and Evaluation Division (RED),
BRAC, 75 Mohakhali, Dhaka 1212, Bangladesh; [email protected], [email protected]
2
Department of Geology, Dhaka University,
3
Resources Engineering, KTH, SE-100 44
Stockholm, Sweden
Arsenic contamination, in fact, has become
a global issue of public health as it has been
encountered in many countries and regions
under varying conditions. The presence of
arsenic in groundwater has lead to widespread concern in Bangladesh. According
to the information gathered through the
extensive work of various agencies, at least
one third of the countries domestic hand
tube wells yield water at concentrations
above the Bangladesh limit of 50 µg L-1
and more than 60% of the wells exceed the
WHO provisional guideline value of 10 µg
L-1. Since detection of arsenic contamination in 1993, various studies have provided
useful information regarding origin, occurrence, distribution and the factors controlling the mobilization of arsenic in groundwater. Studies have been undertaken to find
sustainable mitigation of the arsenic problem in Bangladesh. In the process, new
concerns such as change of arsenic concentrations with time and transfer of arsenic
through irrigation need proper attention.
BRAC completed a community based arsenic mitigation study in Jhikorgachha
Upazila, which was started in early 1999
and completed in December 2001. One of
the main objectives of the project was to test
all the tube well water of the study area and
to develop recommendation about the influence of time series and seasonal fluctuation
of arsenic concentration in tube well water.
The current study synthesizes the data generated from the BRAC’s community-based
arsenic mitigation pilot study in Jhikorgachha Upazila with financial support from
UNICEF and the Department of Public
Health Engineering (DPHE) of the Government of Bangladesh. In the present study, we
present the salient characteristics about the
occurrence, distribution and time trends of
the variations in arsenic concentration in the
tube wells of Jhikorgachha Upazila in
southwestern Bangladesh.
The present study reveals subtle changes in
the levels of arsenic concentration in the
tube well water. The decrease in the concentration of arsenic occurred in almost 50% of
the wells of Jhikorgachha Upazila while
46% of the wells showed an increase in the
levels of arsenic. However in 4% of the
wells the no change in the arsenic concentration was observed. The highest concentration
increase in the analyzed tube well water was
91 µg L-1 with a mean increase of 15.7 µg L1
and the lowest decrease was ca. 128 µg L-1
with a mean decrease of ca. 19 µg L-1.
Therefore, it can be said from the findings of
the present study that arsenic concentration
in tube well water might increase or decrease
with time; however these results indicate that
there is a strong tendency of a reduction in
the levels of arsenic concentration with time
depending on the local hydrogeological conditions.
40
43. Distribution of arsenic in three geochemical fractions of surface sediments
from coastal sites of Sonora, Mexico
M.E. Jara-Marini and L. García-Rico
Centro de Investigación en Alimentación y
Desarrollo, A.C; Division of Food Science, km
0.6, Carretera a la Victoria, PO Box 1735,
Hermosillo, Sonora 83000 Mexico
Arsenic is widely distributed in marine
environments and their interaction properties are determined by chemical and
physiochemical parameters, as well as its
toxic effects in the marine organisms. An
indirect metal toxicity evaluation has been
performed by operational fractionation
using selective chemical extraction solutions. Sonora is one of the principal fishery
producers in Mexico and in a previous
study, a range of 0.09-7.71 µg g-1 of total
arsenic was detected in surface sediments
of oyster farms of the Sonora state. For this
reason, the aim of this study was evaluate
arsenic distribution in geochemical fractions of surface sediment of four oyster
culture sites in the Sonora coast using a
three step microwave sequential extraction
scheme. Fifty-four surface sediment samples were collected from February to August 1999. A microwave selective extraction scheme was used. Arsenic concentration was determined in exchangeable (EF),
bound to organic matter (OMF) and residual (RF) fractions by hydride vapour generation coupled to an atomic absorption
spectrophotometer. Duplicates, blanks and
standard reference material were analyzed
during the procedure. Statistical analysis
were performed using ANOVA-General
Linear Model, Fisher´s LDS mean comparison and Pearson correlations. The total
mean arsenic range of concentration (EFRF) was 0.10-6.59 µg g-1. By study sites
wide ranges were also detected (µg g-1):
Puerto Peñasco 0.08-6.20, Caborca 0.115.35, Hermosillo 0.14-7.30 and Guaymas
0.07-8.68. No significant Pearson correlations (p>0.05) were detected. Furthermore,
the sites show a similar concentration of
arsenic in the EF and OMF fractions, but
slightly higher in Caborca and Hermosillo
sites. Both sites are associated to agricultural
districts, it is possible that arsenic has been
mobilized from deep volcanic deposits into
the watertable that is used for agriculture and
drinking needs in the cities. Arsenic concentrations detected may be also related to fertilizers that could be used in intensive agriculture. These arsenic concentrations ranges
were similar to those reported in nonpolluted sediments. Highest (p<0.05) mean
concentration of arsenic (>95%) was detected in the RF and then potentially
bioavailable arsenic was of minimal toxic
risk. However, arsenic may mobilize to
bioavailable fractions by changes in environmental factors (e.g., pH, salinity and redox potential), increasing its toxic potential
to biota and producing bioaccumulation. In
conclusion, the sites studied are pristine in
arsenic levels but is important to keep monitoring sediment, water, and biomonitor organisms to detect alterations of arsenic
bioavailability.
44. Using permeable compost barriers for
accelerated release of arsenic from contaminated sites
Ralf Köber1, Jürgen Mattusch2, Birgit Daus2,
Edmund Welter3, Francesca Giarolli4, Markus
Ebert1 & Andreas Dahmke1
1
Institute of Geosciences, University of Kiel,
Ohlshausenstrasse 40, 24118 Kiel,Germany;
[email protected]
2
UFZ – Environmental Research Center
Halle/Leipzig, Germany
3
HASYLAB/DESY, Hamburg, Germany
4
Agency for Environmental Protection and for
Technical Services, Rome; Italy
The bulk of arsenic (As) in the solid phase is
frequently associated with iron (hydr)oxides
at contaminated sites. Slow desorption of As
from iron (hydr)oxide sorption sites can be
problematic because this contaminates
ground water for decades and longer. Vari-
41
ous studies ascribed increasing dissolved
As concentrations to the transformation of
iron (hydr)oxides into iron sulfides which
was initiated by dissolved sulfide that
originated from microbial sulfate reduction.
We investigated if this processes can be
utilized as a source treatment approach
using compost based permeable reactive
barriers (PRB) which are located upstream
of contaminated areas and promote microbial sulfate reduction, or if sulfide supply
rather causes precipitation of arsenic sulfides which would decelerate the As release.
Two sets of column experiments, composed
of sequential columns connected by tubing
were performed. The first column of system 1 was filled with organic matter (40%
compost, 33% chaff, 27% wood chips), the
second with As bearing aquifer sediment
from a former fuchsine production site and
the third with ZVI. In system 2 (reference),
which was run to compare the As release
without preset organic matter, the first column contained As contaminated sediment
and the second ZVI (As removal by ZVI
shall be discussed in a separate presentation).
The As bearing aquifer sediment showed
no significant decrease in As content after
420 days of percolation with sulfide-free
artificial ground water. In contrast, water
that previously passed through organic
matter and exhibited sulfide concentrations
of 10-30 mg L-1 decreased the As content in
the sediment for 87% within 360 days. XRay diffraction (XRD) and X-Ray absorption spectroscopy (XAS) investigations
showed that no arsenic sulfides precipitated, although saturation indices for arsenic sulfides occasionally were near equilibrium. The speciation of dissolved As
(measured by IC-ICP-MS) changed from
initially As(V) dominated to As(III) dominated immediately after starting the sulfide
flushing, which increases the mobility of
As. The resulting solution could appropriately be treated by zerovalent iron. Because
sulfide can be supplied not only by compost
based PRBs but also by direct injection of
solutions with high sulfide concentrations,
sulfide flushing has a wide range of application for source treatment of arsenic.
45. Sulfide – A controlling species for
treatment of As by zero valent iron
R.F.Köber1, E. Welter2, F. Giarolli3, M. Ebert1 &
A. Dahmke1
1
Institute of Geosciences, University of Kiel,
Ohlshausenstrasse 40, 24118 Kiel,Germany;
[email protected]
2
HASYLAB/DESY, Hamburg, Germany
3
Agency for Environmental Protection and for
Technical Services, Rome
Several investigations showed an encouraging potential for the removal of arsenic (As)
from groundwater by granular zero-valent
iron (ZVI). Even though microbial sulfate
reduction (MSR) is a known and omnipresent process in ZVI-PRBs, most of these studies did not consider the presence of dissolved
sulfide. These studies showed that sorption
of As to iron (hydr)oxide corrosion products
is the predominant mechanism under such
conditions. Contrasting to those former studies, we investigated the applicability of this
method and the nature of the As bonding
under conditions with dissolved sulfide.
Sulfide can lower the corrosion rate by precipitation of iron sulfide layers and thereby
decrease the formation of new iron
(hydr)oxide sorption sites for As. Secondly
As can get incorporated in these iron sulfides. Thirdly As and sulfide could be precipitated as As sulfides like realgar, orpiment
or arsenopyrite. And fourthly the formation
of thio-arsenic (As-S) species can either
diminish the removal from solution by increasing the solubility of As, or otherwise it
can enhance the As removal by sorption of
negatively charged thio-arsenic species to
positively charged surfaces. Because of
those divergent effects on the long-term
42
performance, it was important to investigate the influence of MSR and sulfide.
Three column tests containing ZVI were
performed for the term of one year (with
cis-DCE as a co-contaminant). The input
solutions contained either predominantly
As(III) (2-200 mg L-1) or predominantly
As(V) (4-10 mg L-1). Arsenic outflow concentrations decreased from initially 30-100
µg L-1 to concentrations of below 1 µg L-1
as a result of decreasing outflow pH with
time. XANES and EXAFS spectra indicated that As in the solid phase was not
only directly coordinated with oxygen like
in adsorbed or coprecipitated arsenite and
arsenate. Samples with high sulfur content
showed an additional bonding for which
EXAFS data exhibited a peak between 2.2
and 2.4 Å. This bonding most likely originated from direct coordination of sulfur or
iron with As that is incorporated in iron
sulfides or from adsorbed thio-arsenic species. The formation of this sulfidic bonding
supports removal of As by ZVI since sulfide production by MSR is ubiquitous in
ZVI-PRBs. Whereas degradation of cisDCE significantly decelerated with time
half life-times for As removal were relatively constant. Association of As with
sulfur is likely to account for the fast and
constant As removal that makes As removal by ZVI-PRBs a much more durable
process than degradation of chlorinated
aliphatics.
46. Bioavailability of arsenic species in
food: practical aspects for human health
risk assessments
Laparra, J.M.1, Vélez, D.1 *, Barberá, R.2, Farré,
R.2, Montoro, R.1
1
Institute of Agrochemistry and Food Technology (CSIC), Apdo. 73, 46100 - Burjassot (Valencia), Spain
2
Nutrition and Food Chemistry. Faculty of
Pharmacy, University of Valencia, Avda.
Vicente Andrés Estellés s/n, 46100 - Burjassot
(Valencia), Spain
Humans are fundamentally exposed to arsenic, a metalloid widely distributed in nature,
through the ingestion of food. The toxicity of
arsenic depends on its chemical form –
hence the importance of As speciation in the
assessment of toxicological risk. The studies
of arsenic in foods have mainly focused on
the characterization of As species in raw
products. However, to date there have been
no antecedents of studies on the bioavailability of arsenic and its chemical species in
foodstuffs.
Three groups of foods have been selected for
estimating the bioavailability of arsenic:
algae (due to their high As content); fish
(due to its important contribution to As intake); and rices (since the latter constitute
the main source of As for over 50 million
people). Simulated gastrointestinal digestion
has been used to assess bioaccessibility
(maximum soluble concentration of the element) as a prerequisite to absorption, with
the incorporation of an in vitro cell culture
(Caco-2 cells, a validated intestinal epithelial
model) to estimate retention and transport,
with the purpose of affording an improved
approximation to the actual in vivo situation.
The bioaccessibility of arsenic and its
chemical species in the analyzed foods is
high (>60%) – thus reflecting high solubility
and availability for absorption in the gastrointestinal medium. Cooking does not modify
the chemical species or reduce bioaccessibility. Based on the bioaccessible fraction of
the foods studied, the cellular retention of
arsenic is seen to be very low (1-6%), with
comparatively superior transport performance (4-18%) of the different species.
The studies conducted may be regarded as a
pioneering effort in the evaluation of the
toxicological risk posed by arsenic and its
chemical species in foods, by contemplating
the bioavailability of As as it is found in
food prepared for actual consumption.
43
47. Investigation of arsenic accumulation
by vegetables and ferns from Ascontaminated area in Brazil
48. Hydrogeochemistry of arsenic in the
regional Loessic aquifer in the southwest
of Buenos Aires Province, Argentina
Helena Eugênia Leonhardt Palmiere1, Olivia
Vasconcelos2, Julio Silva2, Eleonora
Deschamps3
Fabiana Limbozzi1, A. Guillermo Bonorino2 and
Marcelo J.Avena1
1
Nuclear Technology Development Centre/
National Commission for Nuclear Energy
(CDTN/CNEN) Belo Horizonte, Minas Gerais,
Brazil; [email protected]
2
Department of Metallurgical and Materials
Engineering, Universidade Federal de Minas
Gerais, UFMG, Belo Horizonte, Brazil;
[email protected]
3
Fundação Estadual do Meio Ambiente-FEAM,
Av.Prudente de Morais, 1671, 30380-000,Santa
Lucia, Belo Horizonte,MG, Brazil;
[email protected]
In Brazil hydrothermal gold deposits in the
state of Minas Gerais, contain varying proportions of gold bearing sulfides, such as
arsenopyrite, pyrite and pyhrrotite. Soil and
sediments around gold ore deposits and
mining areas present positive anomalies
(median concentrations > 100 mg kg-1) and
wide ranges (<20 to 2000 mg kg-1) even in
densely populated area. Total arsenic concentrations in soil, plants and vegetables
were determined by graphide furnace
atomic absorption spectrometric (GFAAS),
inductively coupled plasma mass spectrometry (ICP-MS), neutron activation
(NA), and by energy dispersive spectrometry (EDS). The ferns Pteris Vittata and Pityrogramma calomelanos extract arsenic from
the soi and translocate it onto their fronds
showing higher arsenic concentration in the
leaves (from 102 to 2585 µg g-1) than in the
rhizoid (from 55 to 128 µg g-1). All vegetables from private gardens investigated present increased As-uptake in both their edible and non-edible parts. Enrichments differed between species but reached elevated
values.
1
Departamento de Química, Universidad
Nacional del Sur, Av. Alem 1253; (B8000CPB)
Bahía Blanca, Argentina; [email protected],
[email protected]
2
Departamento de Geología, Universidad
Nacional del Sur, San Juan 670; (B8000ICN)
Bahía Blanca, Argentina; [email protected]
The phreatic water of the regional aquifer in
the southwest of Buenos Aires province is
the source of water for both the agricultural
production systems and the supply of drinking water of all the rural populations of the
region. Much of the water witdrawaled from
the aquifer contains naturally occurring As
from the plio-pleistocene loessic sediments
in levels higher than WHO guideline value
and the Argentine national standard.
An investigation has been carried out to examine occurrence of arsenic and mechanisms of As release to groundwater at the
Napostá Grande drainage basin of the Sierras
Australes’ occidental drainage slope.
Total arsenic, iron, major cations and anions
were measured in water samples collected
from holes and/or wells with windmills or
submergible pumps and interstitial water
extracted from sediments of vadose zone
through immiscible liquids displacement
method. Arsenic contents were determinated
also in sediments, volcanic glass and calcretes to delineate interrelationships.
Total arsenic concentrations range between 1.5
and 204.6 µg L-1 (mean value: 72.2 µg L-1) in
groundwater, 10.7 and 375.4 µg L-1 (176.8 µg
L-1) in interstitial water, 3.0 and 10.0 mg L-1 (5.8
mg L-1) in sediments, 7.6 and 21.3 mg L-1 (14.0
mg L-1) in calcrete, and between 2.2 and 5.0 mg
L-1 (3.2 mg L-1) in volcanic glass. Among the
investigated groundwater samples, 90% exceed
the WHO guidelines value at full length of the
basin, including the upper basin.
44
Very weak correlations with iron contents
suggest that redox processes containing
iron and arsenic are not dominant mechanism controlling As release to groundwater.
Instead, arsenic groundwater correlates
positively with alkalinity, so that bicarbonate leaching could be the main mechanism
to mobilize arsenic in a loessic aquifer.
49. Volcanic pollution of Arsenic and
Boron at Ilopango Lake, El Salvador
D.L. López1, L. Ransom1, J. Monterrosa2, T.
Soriano3, F. Barahona3, J. Bundschuh4
Department of Geological Sciences, Ohio University, Athens, Ohio 45701, USA;
[email protected]
1
Fundacion de Amigos del Lago de Ilopango,
San Salvador, El Salvador, Central America
2
Departamento de Fisica, Facultad de Ciencias
y Humanidades, Universidad de El Salvador
3, 4
International Technical Cooperation Program, CIM (GTZ/BA), Frankfurt, Germany;
[email protected]
3
Instituto Costarricense de Electricidad (ICE),
UEN, PySA, Apartado Postal 10032, 1000 San
José, Costa Rica
Ilopango lake in central El Salvador, Central America, has an area of 184.9 km2 and
maximum depth of 240 m.
More than 300,000 inhabitants live in the
drainage basin of the lake and use its water
even when high concentrations of B and As
make this water unsuitable for human consumption. High deforestation, fertilization,
and industrialization in the lake basin contribute to the environmental degradation of
Ilopango. The lake has seasonal stratification.
Between November and March the lake
shows almost isothermal and oxygenated
conditions. High wind velocities and slightly
lower air temperatures during this time of the
year produce convective water movement
and mixing of the water column. In comparison, from March to November, high air temperatures and low wind velocities produce a
mild thermal stratification. The water and
sediments of Ilopango lake have been sampled
and analyzed for main cations and heavy metals, especially B and As. For the waters, B concentrations range from 1.5 to 8.7 mg L-1 and
As concentrations from 0.15 to 0.77 mg L-1,
with the higher values to the South and lower
values close to Cerros Quemados Islands (at
the lake center), where the last volcanic activity happened in 1880. In comparison, the As
concentrations in the sediments was high at
Cerros Quemados (86 mg kg-1 sediment),
which also has the lowest concentration of organic matter. The sediment sample collected
close to the confluence of Rio Chaguite show
high concentrations of B, As, and Li (3.4 g kg-1,
103 and 55 mg kg-1 of sediment respectively)
as well as other heavy metals. These results
suggest that two sources of As and other heavy
metals can be identified for Ilopango waters.
One is the internal sediments of the lake that
contain the volcanic products of the last eruptions of this caldera and are rich in As and B,
and the other is the material transported to the
lake by the Chaguite River. Leaching and erosion from the volcanic deposits of the lake
basin as well as possible anthropogenic inputs
could be the sources for the river loads. The
ash of the last calderic eruption of Ilopango
(about 2000 years ago) cover all El Salvador
and part of Central America and could be the
source of As contamination for other aquifers.
50. The use of synchrotron-based microX-ray techniques to determine arsenic
speciation in contaminated soils
Jorge Luis López-Zepeda1, Mario Villalobos1,
Matthew Marcus2, Margarita Gutiérrez-Ruiz1,
and Francisco Martín Romero1
1
Grupo de Bio-Geoquímica Ambiental, LAFQA,
Instituto de Geografía, UNAM, 04510, D.F.,
México; [email protected]
2
Advanced Light Source, Lawrence Berkeley
National Laboratory, MS 2R0222, Berkeley,
California, 94720-8199 USA
Molecular-scale speciation of environmentally relevant trace elements in soils is of
utmost importance to understand their bio-
45
geochemical behavior, including prediction
of their mobility and fate in the environment. In the case of arsenic, extensive
evidence exists on the commanding role of
iron oxides in the regulation of arsenic mobility in aqueous environments, such as
soils, through mechanisms that range from
adsorption to precipitation. Recently, the
involvement of other trace metals in coprecipitation processes of arsenic is under
investigation.
Mining and mineral processing activities
alter the natural stability of arsenic mainly
via oxidation, rendering wastes containing
arsenic species that are more mobile than
the originally reduced counterparts. Nevertheless, we have found a greatly reduced
mobility of oxidized arsenic in soils contaminated by these kinds of wastes compared to that in the original wastes, in three
different areas of México, regardless of
their specific origin: Real de Ángeles,
Zacatecas, contaminated by mine tailings
from mining of Pb, Ag y Zn ores; San Luis
Potosí, capital of the state with the same
name, near Cu, As and Pb refinement
plants; and Monterrey, Nuevo León, surrounding a Pb smelting plant where calcium arsenate wastes were generated.
The present work reports the kind of information provided, and procedures followed
to determine the molecular-scale speciation
of arsenic in heterogeneous soil samples,
by using micro-X-ray techniques from synchrotron sources, including µ-XRF (X-ray
fluorescence), µ-XRD (X-ray diffraction),
and µ-XAS (X-ray absorption spectroscopy). Suitable soil samples with high total
arsenic contents, but low aqueous arsenic
levels were processed at the Advanced
Light Source of the Lawrence Berkeley
National Laboratory, in California, USA.
Synchrotron facilities provide extremely
bright X-rays obtained from circular motions of electrons accelerated to near speeds
of light. These X-rays allow structural determinations of trace element local environments to very accurate levels, including
interatomic distances to 0.03 Å, and nature
and number of neighbors in first few atomic
shells surrounding the element of interest.
The data obtained through simultaneous
processing of adequate arsenic standards
provided structural information on the correlation and involvement of other metal
cations such as Fe, Pb, and Zn, in the immobilization processes of arsenic in soils. The
latter include formation of adsorbed species
and surface precipitates on mineral oxides
surfaces.
51. Effect of Irrigation with Wastewater
on Arsenic Concentration in Soils and
Selected Crops of Irrigation District 03,
Hidalgo State, Mexico
C. A Lucho-Constantino1,2, L.M. Del Razo3, R.I.
Beltrán-Hernández,4, I.Sastre-Conde5, M. Cebrián3, F. Prieto-García4, H.M. Poggi-Varaldo1
1
CINVESTAV del IPN, Dept. Biotechnology and
Bioengineering, Environmental Biotechnology
R&D Group, P.O.Box 14-740, México D.F.,
07000, México; [email protected]
2
UTTT, Tepeji del Río, Hgo. México
3
CINVESTAV del IPN, Section of Toxicology,
México D.F., México
4
UAEH, Chemistry Research Centre, Pachuca,
Hgo, México
5
Conselleria d’Agricultura i Pesca, Government
of Islas Baleares, Palma de Mallorca, Islas
Baleares, Spain
The accumulation and distribution of arsenic, boron, selected heavy metals and several
major elements in 31 agricultural soils of the
District 03 (DR03) in the State of Hidalgo,
Mexico, irrigated with raw wastewater for 0
to 90 years, was evaluated. Also, four control soils (rainfed) were analyzed. Samples
of topsoils (0-30 cm depth) were extracted
using a modified Tessier method. As a complementary study, arsenic and heavy metal
concentrations were determined in selected
crops harvested in soils of DR03.
Total concentrations of the species tested fell
in the following ranges: 10- 9009 mg K kg-1,
144 – 1002 mg Na kg-1; 9.3 – 123.8 mg B
46
kg-1, 0.06 – 5.6 mg Cd kg-1, 7.63 – 256.6
mg Cr kg-1, 4.0 – 660 mg Pb kg-1. The concentrations of As were below the detection
level of the method (0.03 mg kg-1) in all
soils, whereas soils S3 (Ixmiquilpan1), S4
(Ixmiquilpan2), S11 (Rosario) and S18
(San Juan Tepa) showed Hg contents above
the detection level of the method, with values 0.77, 0.03, 5.59, and 3.15 mg kg-1. The
concentrations of total Cd, and Cr were
generally below the maximum permissible
levels set by the regulations of the European Union. By contrast, cadmium and lead
in several soils were in the middle to the
high side of European Union maximum
ranges. Moreover, contents of Pb in the
most mobile fractions (soluble and exchangeable) were significant in a range
between 3 to 28%. This distribution translates into concentrations of soluble plus
exchangeable lead around 2 mg Pb kg-1 or
higher in several soils, significantly superior to the Swiss tolerance limit of 1.0 mg
Pb kg-1 for mobile fractions of lead in soils.
Contents of arsenic in alfalfa (Medicago
sativo) ranged between 0.003 to 0.09 mg
kg-1, depending on the soil and the part of
the plant (i.e., stem, leaves) whereas As
concentrations in nopal (Opuntia robusta)
were up to 0.54 mg kg-1 for irrigated soils.
By contrast, As content in nopal grown in
control soils (rainfed) was in the range
between detection level to 0.003 mg kg-1.
Yet, lead concentration in alfalfa and nopal
reached values as high as 30 - 46 mg kg-1,
whereas the corresponding levels in nopal
harvested in control soils was 0.04 mg kg-1.
It seems that long term irrigation with
wastewater of agricultural soils in Irrigation
District 03 of Mexico does not pose an
immediate risk from the standpoint of arsenic accumulation in soils and crops, although lead contents in several soils, alfalfa
and nopal seem to be of concern. Further
monitoring and research are required to
have a more complete assessment, although
it seems that lead accumulation would jus-
tify the implementation and enforcement of
crop restriction regulations in some soils.
52. Identification of arsenic tolerant
plants in the mining district of Villa de la
Paz, S.L.P.
B.P. Machado-Estrada1, J. Calderón-Hernández2,
L. Carrizalez-Yañez2, J.A.Reyes Agüero3, R.
Briones-Gallardo1
1
Facultad de Ingeniería, Instituto de Metalurgia,
U.A.S.L.P., San Luis Potosí, S.L.P., México;
[email protected]
2
Laboratorio de toxicología ambiental, Facultad
de Medicina, U.A.S.L.P., San Luis Potosí.
México
3
Instituto de Investigaciones de Zonas Desérticas,
U.A.S.L.P, San Luis Potosí, S.L.P., México
The identification of native plants that are
both tolerant to arsenic and phytocumulator
of arsenic is of main importance in remediation and restoration of soils impacted by
mining activity. This work shows the results
obtained after the analysis of nine physiognomical predominant plants in the mining
district of Villa de la Paz-San Luis Potosí,
Mexico. All plants were identified taxonomically Five sampling areas were defined
by isoconcentration maps of arsenic (Razo,
2004). Total arsenic concentrations in the
sampling areas are in the range of 10 µg.g-1S
to 10224 µg.g-1S. Total arsenic concentration
measurements in dry biomass (DB) were the
result of the sum of independent arsenic
concentration analysis in different sections
of the plant (root, stem and leaves). Total
digestion of plants was performed using both
the hotplate method and total soil digestion
by the microwaveoven method.
Arsenic was determined using a flow injection analysis system (FIAS) coupled to an
atomic absorption spectroscopy system
(AAS). Sampling areas with a concentration
of up to 10224 µg.g-1S of arsenic, showed
that accumulated concentration in Solidago
scabrida biomass (330 µg.g-1DB) was 3.5
times higher than accumulation in Viguiera
47
dentata (95 µg.g-1DB) and Brickellia veronicifolia (90 µg.g-1DB) and 4.7 times
higher than in Flaveria appositifolia (70 µg
g-1DB). Also, it was observed that the accumulation of arsenic in root on Solidago
scabrida was of 89%; Viguiera dentata
accumulated 82% of As in leaves; Brickelia
veronicifolia accumulated 56% and 36% of
As in leaves and root, respectively; while
Flaveria appositifolia accumulated 49% and
48% of As in leaves and root, respectively.
For Brickellia veroncifolia a linear relationship was observed between the arsenic
concentrations in biomass and the total
arsenic concentration in soil.
The results suggest that the mechanisms of
arsenic accumulation in all plants analyzed
are different. These differences can be attributed to several factors: physicochemical
processes or biological mobilization at the
rhizosphere of the plant; possible symbiotic
associations; exposure to the biological
surface; and local physical processes (e.g.,
atmospheric mineral dispersion). This work
shows the importance of defining the arsenic distribution in different sections of the
plant as a selection criterion for the potential use of such plant for remediation treatment.
53. Effect of current density in the arsenic removal by electrocoagulation from
groundwater
A. Maldonado Reyes1, C. Montero
Ocampo1
1
CINVESTAV. U. Saltillo, P.O. Box 663,
Saltillo Coah, México 25000;
[email protected]
Elevated concentrations of arsenic (As) are
found in groundwater in many regions of the
world due the anthropogenic activities and
natural process. Arsenic drinking water contamination occurs is a world wide concern
because millions of people may be affected in
several. In the central part of northern of
México this problem is severe because re-
cently underground sources of water have been
located with approximate arsenic contents of
120 µg L-1, which is approximately a magnitude order higher than the maximum value
admissible for drinking water (<10 µg L-1).
Exist important methods for removal As
from drinking water, but one of the more
promising methods of total As removal from
drinking water is the electrocoagulation (EC)
method due to several advantages that presents respect with other conventional methods as for example, it does not requires addition of chemical reagents and produces very
small amount of sludge. In natural groundwater, inorganic soluble As is normally present in oxidation states 5+ (As(V)) and 3+
(As(III)) (2). As(V) species (H2AsO4- and
HAsO42-) are the most easily removed by
any method because of their ionic nature.
The opposite case found for As(III) species
(predominantly H3AsO3) which are difficult
to remove. However, generally is assumed
that small amounts of As(III) are present
along with As(V) in groundwater
This study compares the total arsenic removal from contaminated (120 µg As L-1)
groundwater degree by EC using five different currents densities. The experiments were
carried out using iron electrodes in galvanostatic conditions for 1 hour and five
current densities, 1.5, 3, 4.5, 6 and 12 mA
cm-2 at constant temperature (30°C). The
results have shown that As content was removed reaching values lower than 10 µg L-1
at the end of the EC process when the current was greater than 4.5 mA cm-2, that can
be explain as follow: when the current increases, the amount of iron dissolved also
increases and therefore the insoluble iron
species which form complexes with the arsenates present in the underground water are
also increased. This evidence that the ratio
Fe/As is very important in the As removal by
this EC process, its means that when the iron
dissolves anodically increase, the As total
removal by this EC process is also increased.
48
54. Long-term environmental impact of
As-dispersion in Minas Gerais, Brazil
Jörg Matschullat1, Eleonora M. Deschamps2,
Thomas Gabrio3, Nilton de Oliveira4, Kirstin
Raßbach1, Marcelo José de Oliveira Vilhena5,
Ursula Weidner3
1
Interdisciplinary Environmental Research
Center, TU Bergakademie Freiberg, Brennhausgasse 14, D-09599 Freiberg, Germany;
[email protected]
2
Fundacao Estadual do Meio Ambiente
(FEAM), Avenida Prudente de Morais 1671,
CEP 30380-000 Belo Horizonte, Minas Gerais,
Brazil
3
Landesgesundheitsamt Baden-Württemberg,
Department of Toxicology, Widerholdstr. 15,
D-70174 Stuttgart, Germany
4
Fundacao Ezequiel Dias (FUNED), Instituto
Octávio Magalhaes, Rua Conde Pereira
Carneiro 80, CEP 30510-010 Belo Horizonte,
Minas Gerais, Brazil
5
Companhia de Saneamento de Minas Gerais
(COPASA), Br 356, km 4, Trevo de Nova
Lima, Bairrio Belvedere, CEP 31950-640 Belo
Horizonte, Minas Gerais, Brazil
To answer the question whether up to 250
years of continual gold mining, and related
activities in parts of the Iron Quadrangle,
Brazil, have lead to arsenic-pollution problems, a comprehensive research project was
launched in1998. Within this project, air,
soils, surface and groundwater, suspended
particulates and fresh, unconsolidated sediments were sampled and investigated together with home-grown vegetables, human
urine and hair, and private water supplies.
All sampling, sample processing and analytical work has been done until today by
the same people with the same methods
applying strict quality control measures.
Elevated to very high soil As-concentrations (50–1000 mg As kg-1) in living
quarters, and extremely high (percentage
range) As-values on derelict industrial sites,
including old tailings surfaces characterize
the areas. Soil dust, As-enriched vegetables, and partly As-contaminated water
from private wells and unauthorized sur-
face sources explained the partially high Asload particularly in children of the area (up
to 60 µg As L-1 urine). This load was successfully lowered over the past few years,
although the exposure of some families
could not be improved. The complex evaluation of all environmental compartments and
their interactions allows for a thorough understanding of the dominating processes and
As-pathways. Thus, a detailed risk assessment is possible and, following the results,
additional action to improve the situation is
being suggested.
55. High level of arsenic in children’s hair
from communities exposed to well water
contaminated with arsenic despite its limited use as drinking water
Rebeca Monroy-Torresa, Alejandro E. Macíasa,
Juan Carlos Gallaga–Solorzanob, Enrique Javier
Santiago-García, Isabel Hernández-Ramosa
a
University of Guanajuato School of Medicine at
León, Mexico
b
State Public Health Laboratory, Guanajuato,
Mexico
Objective: To know the level of arsenic
absorption in children chronically exposed to
contaminated well water.
Design: Cross sectional study to compare
arsenic level in hair of children exposed and
unexposed to contaminated well water.
Subjects/setting: We recruited school children with at least two years of residency in
four rural communities in Guanajuato,
México on 2004; two villages had arsenic
contaminated well water.
Main outcome measure: Arsenic in hair
measured by hydride generation atomic absorption spectrophotometry.
Statistical analyses performed: Chi square,
Fisher’s exact test, t test or Wilcoxon, used
as appropriate.
Results: Overall, 110 children 10 years old
on average (range 7-14) were included; half
49
were males. Neither age, sex, nutritional
status nor total water consumption were
different between exposed and unexposed
groups. Among 55 exposed children, mean
arsenic level on hair was 1.3 mg kg-1 (range
<0.006 - 5.9); 49 had abnormal levels
(>0.05 mg/kg) and only six had undetectable values. All unexposed children had
undetectable arsenic levels on hair. Categorical analysis showed a statistical relationship between the high level of arsenic
in water and hair (p< 0.0001). However,
compared to unexposed children, exposed
kids drank with less frequency well water
at school (3.6% vs. 58.2%, p < 0.0001) or
at home (7.3% vs. 38.1%, p < 0.0001).
Conclusion: The use of contaminated well
water to cook or for agricultural purposes
may play an important role in chronic
population exposition to arsenic.
Application: Analyses of local practices
that enhance the exposure might help understand and limit the problem.
56. Presencia de arsénico en areniscas:
Caso de estudio en un acuífero del
Mediterráneo Español
I. Morell1, M.V. Esteller2, E. Giménez3
1
Departamento de Ciencias Experimentales Universitat Jaume I de Castellón, España;
[email protected]
2
CIRA - Universidad Autónoma del Estado de
México, México; [email protected]
3
Universidad Católica de Ávila, España;
[email protected]
El acuífero de areniscas del Buntsandstein
(Triásico) es una fuente de abastecimiento
de agua potable para varias poblaciones de
la costa del Mediterráneo, en concreto de
las provincias de Castellón y Valencia. La
explotación de este acuífero se inicio debido a los problemas de calidad (presencia
de nitratos y salinización) que presentan los
acuíferos costeros detríticos.
Este acuífero está constituido por una homogénea y potente secuencia de areniscas
silíceas (cuarzoarenitas), localmente pueden
observarse en contadas ocasiones alguna
intercalación de lutitas rojas, muy compactas
y de escasa potencia. Los componentes principales son granos de cuarzo monocristalino,
aunque también se observan otros cuarzos
policristalinos y algunas láminas de mica.
También se ha reconocido la presencia de
feldespato potásico, moscovita, turmalina,
circón y óxidos de hierro. La matriz es
clorítica y procede de la alteración de micas,
sobre todo biotita, proceso en el que se libera
hierro ferroso que es posteriormente oxidado
y fijado como cemento o matriz, y es el que
de el color rojizo característicos de estas
rocas.
La permeabilidad del acuífero es debida a la
fisuración, la cual presenta diversos grados
de intensidad y penetración que ha dado
lugar a que no toda esta formación conforme
un acuífero y que exista una alta compartimentación. En cuanto a la hidroquímica, se
trata de aguas bicarbonatadas cálcicomagnésicas.
Últimamente, y debido a los cambios en la
normativa sobre calidad del agua de consumo humano que ha fijado un limite de 10
µg L-1 para el As, se ha prestado especial
atención a la presencia de este elemento en
las aguas, habiéndose detectado concentraciones de hasta 14 µg L-1. Por otro lado, altas
concentraciones Fe (830 µg L-1) y Mn (25 µg
L-1) también han sido detectadas en algunos
pozos aunque en otros pozos con As, la concentración de estos elementos es minima.
Otro dato a tener encuenta es que la concentración de As ha aumentado con el tiempo,
pasando de concentraciones inferiores a 2 µg
L-1 hasta de más de 10 µg L-1, en unos 3
años.
Para establecer cual es el origen de este
arsénico se está planteando dos hipótesis: la
oxidación de pirita (cuya presencia ha sido
detectada) por la entrada de oxigeno atmosférico originada por el descenso de los nive-
50
les piezométricos de la zona (la oxidación
del sulfuro podría liberar el As contenido
en él) y/o la desorción de As que esté fijado
en los óxidos de Fe.
57. Hydrogeochemistry of arsenic in
groundwaters from Burruyacú basin,
Tucumán province, Argentina
H. B. Nicolli1,2, A. Tineo1, C. M. Falcón, J. W.
García1, M. H. Merino1, M. C. Etchichury1, M S
Alonso and O. R. Tofalo
1
Instituto de Geoquı´mica, Av. Mitre 3100,
1663 San Miguel, Provincia de Buenos Aires,
Argentina
2
Consejo Nacional de Investigationes
Cientı´fı´cas y Te´cnicas (CONICET), Buenos
Aires, Argentina
[email protected]
The Burrucayú basin (2700 km2 area) in the
Eastern Plain, Tucumán Province, Argentina, has been filled by loess deposits from
Tertiary and Quaternary ages and substantially reworked by fluvial and aeolian processes. Three well-differentiated hydrological environments have been defined: 1) a
lower hydraulic system (below a 200 m
depth) in Tertiary quartzose sands with
thermal anomalies (up to 40ºC); 2) a middle
hydraulic system in Quaternary reservoirs
in alluvial fans with confined levels; and 3)
an upper hydraulic system (between 10 and
40 m depth) corresponds to a low permeability unconfined aquifer made up of siltyclayey sediments. This groundwater is used
by the local rural population.
Groundwaters have a highly variable
chemical composition. Their salinity presents a wide range of variation (TDS from
451 to 4830 mg L-1). Major ion composition is controlled by the reaction of the
silicate minerals and by the carbonate equilibrium. Most groundwaters are hard or
very hard (hardness ranges up to 1130 mg
L-1 CaCO3). Sodium is the dominant cation
(maximum content 1040 mg L-1) and bicarbonate the dominant anion (maximum con-
tent 1080 mg L-1), but in more saline waters
sulphate and chloride contents are high. Sodium mainly results from the dissolution of
sodium plagioclase and is concentrated by
evaporation. Bicarbonate concentrations are
high, the same as the pH values that vary
from 7.2 to 8.6. High nitrate contents are
restricted to shallow groundwaters (maximum 64.8 mg L-1) and lower values, in deep
aquifers. The highest contents result from
agricultural pollution.
Trace-element contents in groundwaters
from Burruyacú basin exhibit a high variability with an observed range of 15.8-1610
µg L-1 in shallow groundwaters. Fluorine
variation range is also high (149-8740 µg L-1).
Arsenic correlates positively with several
other trace elements that also reach a high
concentration: vanadium contents reach up
to 1090 µg L-1; uranium, up to 155 µg L-1;
boron, up to 6740 µg L-1; molybdenum, up to
90.1 µg L-1 and antimony, up to 0.46 µg L-1
in shallow groundwaters.
There is no regional trend in the distribution
of trace elements, and local phenomena play
a fundamental role: geomorphological factors (small slope variations) influence the
flow velocity of the waters as well as the
variations in the composition of the host
sediments. The trace elements are strongly
concentrated in materials of volcanic origin,
the Quaternary loess being their source. The
main components are feldspars, quartz and
volcanic glass shards, with minor amounts of
muscovite, calcite and lithic fragments, with
opal and chalcedony. Heavy minerals (<5%)
are pyroxene and amphibole, with minor
amounts of epidote and biotite, and scarce
zircon. The clay minerals have a low degree
of crystallinity and illite prevails over smectites and interstratified illite-montmorillonite.
Sorption processes of arsenic and other trace
elements onto Al and Fe oxide and oxihydroxide surfaces tend to restrict the mobility of those trace elements and consequently
control their distribution in groundwaters.
51
However, sorption processes are limited in
waters with high pH values and high bicarbonate contents. Under such conditions,
desorption processes may occur, increasing
their mobility and trace-element contents in
shallow groundwaters.
58. Evaluation of the human contamination by arsenic in the municipal district
of Santa Bárbara, MG, Brazil
tion of health, which were later used to study
the results. Approximately 700 samples were
collected and were analyzed through atomic
absorption spectrometry with hydrite generation. The results were corrected by the
creatinine, correlated with the answers of the
questionnaires, and it was evident that the
arsenic content of the urine samples increased with the arsenic enrichment in the
different environmental compartments.
Nilton de Oliveira Couto e Silva1, Clélia
Aparecida Rocha1, Tatiana Vieira Alves1,
Eleonora Deschamps2, Sandra Maria Oberdá2
59. Factores de transferencia (FT) suelohojas de As en Prunus persica L. modificaciones por la aplicación de sulfato de
hierro monohidratado (SFM)
1
Laboratório de Contaminantes Metálicos,
Divisão de Vigilância Sanitária, Instituto
Octávio Magalhães, Fundação Ezequiel Dias,
Rua Conde Pereira Carneiro, 80, CEP: 30510010, Gameleira, Belo Horizonte,MG, Brazil;
[email protected]
2
Fundação Estadual do Meio Ambiente-FEAM,
Av. Prudente de Morais,1671,
CEP: 30380-000, Santa Lucia, Belo Horizonte,
MG, Brazil; [email protected]
Santa Bárbara, located in the Iron Quadrangle, is rich in iron ore and hydrothermal
gold deposits, which contains several sulfides as principal accompanying minerals,
among them the arsenopyrite (FeAsS),
principal mineral arsenic bearer. With the
intense activity of gold mining in the area,
the arsenic minerals are liberated to the
external compartments, contaminating the
waters, soils and sediments. The objective
of this research was the evaluation of the
contamination of the local population by
the arsenic and the identification of the
main sources of contamination. Five places
of the area were studied between 2002 to
2005: Barra Feliz, Brumal, Sumidouro,
Santana do Morro and "Rua do Carrapato",
occasion when 6 campaigns were carried
out by collecting samples of the residents’
urine, mainly the children, who were the
most affected. During the collecting time
the participants were invited to answer an
epidemic questionnaire containing information about the lifestyle, feeding and situa-
b
Orihuela, DL. aHernández, J.C.; bPérezMohedano, S. bMarijuan, L.
a
Escuela Politécnica Superior La Rábida. Universidad de Huelva. Huelva. España; bHUNTSMAN-Tioxide. Madrid. España; [email protected]
La cantidad de un elemento que la planta es
capaz de absorber de un suelo ha sido objeto
de numerosos estudios científicos. El Factor
de Transferencia (FT) se define, conceptualmente, en la literatura científica, como la
relación entre la concentración en la planta,
o en un órgano de ella, de un elemento determinado y la concentración de ese elemento en el suelo. Esta definición desde una
óptica matemática sería un modelo lineal
muy simplista. Los modelos matemáticos
que expresan los datos experimentales del
Factor Transferencia (FT) serán, por lo
general, más complicados, pero siempre
tienen la notable ventaja de ayudar a
entender parte del proceso de traslocación de
los elementos nutritivos desde los suelos a
las plantas cuantitativa y temporalmente.
El objeto de este trabajo es estudiar en un
cultivo de melocotones, Prunus persica L.
los FT del As cuando la solubilidad del suelo
se altera por un proceso de corrección de pH.
Concluimos que los modelos de transferencia de As expresados por el valor de FT
desde suelos calizos hacia las hojas en cultivos de melocotón (Prunus persica L.) son
52
por lo general modelos lineales y casi horizontales expresando el hecho de que las
concentraciones de este elemento en hojas
son independientes de las concentraciones
en el suelo, y que las alteraciones del pH
modifica escasamente los valores de FT.
60. Desarrollo de un sistema de
información geográfica para el
municipio de Zimapán Hidalgo, México
E. Ortiz1, I. Reséndiz1, E. Ramírez1, M.A. Armienta2, V. Mugica1
1
Universidad Autónoma MetropolitanaAzcapotzalco, Av. San Pablo 180, Col Reynoza, México D.F. 02200
2
Instituto de Geofísica, UNAM, México 04510 D.F.
En este trabajo se desarrolla la metodología
para el diseño de un sistema de información
geográfica que permita la identificación de
sitios y fuentes potenciales de contaminación de agua y aire en el municipio de
Zimapán Hidalgo. En el sistema se incluye
a nivel AGEB: Ubicación geográfica de la
zona de estudio, uso del suelo, meteorología disponible, fuentes de abastecimiento hidrológico, y desarrollo poblacional, localización de la industria, servicios urbanos y transporte. Con el fin de
diagnosticar la exposición al arsénico en
pobladores del municipio de Zimapán, asociándolo a las enfermedades como hipocromia, hipercromia, hiperqueratosis y
zonas verrugosas, se incorpora información
publicada en estudios previos.
61. Sodium arsenite increases calpains activity and induces expression of calpain-10
Patricia Ostrosky-Wegman1, Andrea DíazVillaseñor1, Laura Cruz3, Marcia Hiriart2 and
Mariano E. Cebrián3
1
Department of Genomic Medicine and
Environmental Toxicology, Instituto de
Investigaciones Biomédicas, Universidad
Nacional Autónoma de México, México;
[email protected]
2
Department of Biophysics, Instituto de Fisiología Celular, Universidad Nacional Autónoma
de México, México
3
Section of Environmental Toxicology, CINVESTAV, IPN, Mexico City, México
Type 2 diabetes is a complex disease with
genetic and environmental risk factors.
Chronic arsenic exposure by drinking water
has been epidemiologically associated with
with type 2 diabetes. Single nucleotide
polymorphisms (SNPs) in calpain-10 gene
have been associated with type 2 diabetes in
some populations. Calpain-10 is member of
the family of calcium-dependent nonlysosomal cystein protease and plays an important role in insulin secretion by pancreatic β
cells. The capacity of arsenic to alter calcium
currents and intracellular concentrations has
been shown. This modification of calcium by
arsenic could lead to alterations in calpains
activity inducing a diabetogenic effect. In the
present study we analyzed the interaction
between calpains and sodium arsenite. Non
cytotoxic sodium arsenite dosis in a subcronic exposure model were used to evaluate
calpain-10 expression and functionality in
RINm5F rat insulinoma cell line. Sodium
arsenite (1 µM) increases calpains activity
by 60.3% and there was a 2.79 ± 1.02 foldinduction in the expression of one isoforma
of calpain-10. Major dosis (5 µM) affected
cell viability and cause morphological cell
changes. More experiments are going to be
realized to evaluate specific calpain-10 functionality, alterations in calcium concentration
and to discard the involvement of another
member of the calpain family. The modifications of calpain-10 by arsenic could contribute to the dysfunction of β-cells present in
type 2 diabetes.
53
62. Arsenic mobilization in aquatic sediments of an impacted mining area, north
central Mexico
N.A. Pelallo-Martínez1, R.H. Lara-Castro2,
M.C. Alfaro-De la Torre1, J.Castro-Larragoitia3
1
Facultad de Ciencias Químicas; UASLP, San
Luis Potosí, México;
[email protected];
[email protected]
2
Instituto de Metalurgia UASLP, San Luis Potosí, México
3
Facultad de Ingeniería/Instituto de Geología;
UASLP, San Luis Potosí, México;
[email protected]
The presence of arsenic in groundwater has
been a main environmental research topic in
Mexico for over two decades. There are well
studied sites as the Lagunera Region near the
city of Torreon on the north central zone and
Zimapan in the central State of Hidalgo. In
those places, concentrations from 8 to 1112
µg L-1 As have been reported, with As(V) as
the predominant species. Health risk and
some effects in humans have been also studied.
Previous studies on the mining district of
Villa de la Paz-Matehuala located in the
semiarid Altiplano of Central Mexico reported polluted soils, and aquatic systems
and associated them to the dispersion of
historical and active tailings impoundments, waste rock dumps and historical
refining activities. Arsenic was identified as
the most important pollutant at this site and
reported concentrations in groundwater
exceed more than 100 times the Mexican
Drinking Water Standard.
Our work focuses in elucidating the mechanism of arsenic mobilization between sediments and groundwater in sites (dug wells,
springs and channels) where residues of
mining and smelting activities may have
polluted the groundwater. The results may
conduct to information about the source or
sources of pollution.
Porewater and overlying water concentrations of As and other chemical were obtained using dialysis samplers (peepers)
placed in sediments of three contaminated
sites. Sediment cores were also taken at
those sites. Data showed that total As concentrations in porewater are different from
site to site ranging from 26 to 123 000 µg L1
. However, concentration profiles suggest
As mobilization from sediments to the water
column associated with the sulfides dissolution or the sulfate/sulfide redox process. The
concentrations of total dissolved As change
among the sites probably related to the pollution source or sources but this relationship
with the source has not been demonstrated.
High Arsenic(III) concentrations were determined in two sediment and water sampling sites. Sediment and porewater concentration profiles of As suggest mobilization
from the solid phase followed by diffusion
from the sediment to the water column in
one site. Our results suggest this mechanism
because the maximum concentration of As
occurs near to the maximum of sulfides
[ΣH2S] in pore water. Decreasing concentrations of total As in the more recent sediments occurs near the maximum of dissolved
As in porewater suggesting not only that As
is lost to the water column but also that the
emission of this chemical has probably decreased in the last years.
63. High arsenic in drinking water of
dairy cattles in Cordoba, Argentina and
its transfer to milk
Alejo Pérez-Carrera, Carlos Moscuzza and Alicia
Fernández-Cirelli
Centro de Estudios Transdisciplinarios del Agua.
Facultad de Ciencias Veterinarias, Universidad
de Buenos Aires. Av Chorroarín 280 (C1427
CWO). Ciudad Autónoma de Buenos Aires,
Argentina; [email protected]
The Chaco Pampean Plain of central Argentina constitutes one of the largest regions of
high arsenic groundwaters known, covering
54
around 1x106 km2. The high-As groundwaters derive from Quaternary loess deposits
(mainly silt) with intermixed rhyolitic or
dacitic volcanic ash. One of the most affected region is the province of Cordoba,
where As concentrations that exceed the
maximum level of 50 µg L-1 for drinking
water have been reported. The southeast of
Cordoba is an important milk production
zone in Argentina, where dairy products
consumption is up to 192 equivalent milk
L/inhabitant/ year. As an excretion of the
mammary gland, milk can carry numerous
xenobiotic substances, which constitute a
technological risk factor for dairy products
and above all for the health of the consumer. Nevertheless no studies on the incidence of high-As livestock drinking water
in livestock health and its transfer to milk
have been performed in Argentina.
The aim of the present study was the determination of arsenic content in livestock
drinking water and milk from dairy farms
located in an area of high arsenic groundwaters, to analyse the relation between As
uptake through water and its transfer to
milk. Groundwater is the main source of
livestock drinking water. In 54% of the
analysed wells, the phreatic water was
found between 3 and 8 m, with extreme
depths of 2 and 15 m, while the remaining
wells range in depth from around 80 to 150
m (deep wells). Arsenic concentration in all
phreatic water samples was over the suggested level for occurrence of chronic intoxication in cattle (0.15 mg L-1) and 53% of
them showed higher values than those recommended for livestock drinking water
(0.5 µg L-1). Arsenic concentration in deep
wells was under 0.15 mg L-1. As milk content ranged from 2.8 to 10.5 ng g-1 for dairy
farms using phreatic groundwater, while a
mean value of 0.5 ng g-1 was obtained for
farms using deep wells.
In order to analyse the relation between As
uptake through water and its transfer to
milk, four farms (Holstein dairy cows)
were selected. Two of these stablishments
where medium size (100-120 dairy cows)
and two were small (10-20 dairy cows). One
medium size stablishment with As water
concentration of 0.04 mg L-1 was also selected for comparison. If As water content is
considered as the only exposure dosis of As
to milk, assuming steady state conditions, a
biotransfer factor (BTF) may be calculated
as: concentration of As in milk (mg L-1) /
daily animal intake of As (mg day-1). The
values obtained ranged from 5.2 x 10-5 to 1.8
x 10-4. No significant differences were found
between the five farms analyzed, where food
is the same in all cases and one of them has
very low As water content.
Although As transfer to milk is a complex
process, the fact that a BTF may be estimated through As water contribution reinforce the importance of dairy cattle drinking
water quality not only from a productive
point of view but also because of its incidence in the agricultural food chain.
64. Arsenic in Argentina groundwater:
need to develop methodologies to define
problems and arrive to actual solutions
J. Pflüger1, S.S. Farías2, J. Bundschuh4, M. E.
Garcia3
1
Ente Nacional de Obras Hídricas de
Saneamiento. Av. L. N. Alem 628 pisos
10/11/12/13. Capital Federal. Buenos Aires.
2
Comisión Nacional de Energía Atómica. Centro
Atómico Constituyentes. Av. Gral. Paz. 1499
(1650). San Martín. Provincia de Buenos Aires.
3
International Technical Cooperation Program,
CIM (GTZ/BA), Frankfurt, Germany - Instituto
Costarricense de Electricidad (ICE), UEN, PySA,
Apartado Postal 10032, 1000.San José, Costa
Rica; [email protected]
4
Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés. P. Box 10201, La Paz,
Bolivia; [email protected]
In Argentina, water quality is affected in
more than a half of its provinces by the presence of anomalous, high contents of arsenic
55
and other toxic trace elements. This fact
was well known since the beginnings of
1900, and studies developed during last
century identified that the source was in
most of the cases due to the natural presence of these contaminants in soils and
their migration to aquifers through time.
These aquifers have supplied groundwaters
to first inmigrants and nowadays provide
cities, towns and disperse rural populations
with this valuable resource all around
Chaco-Pampean Plain and also in some
Argentinian Western and North-Western
areas.
Although the situation has been thoroughly
described and divulged, it has not been
treated in a systematic manner in the whole
country. In this way, there are some counties that develop and perform their own
mitigation programs and there are some
other that disregard this situation with the
subsequent damage of affected population
health.
A number of Argentinian government organisations are devoted to arsenic and other
toxic trace elements studies about occurrence and remediation; Water Resourses
Office, Health and Environment Department and Federal Planning Department can
be mentioned; even though their works are
sometimes overlapped.
The present work appoints to the organization of resources to carry out a detailed
analysis of the situation, through to knowledge of contamination levels, their geographic limits and localization, the statement of remediation tecnologies adequate
to each particular case, fitting the budget
and cost-benefit equations.
This survey also mention the programs that
are being performed, the fulfilled investments and those that are going to be realized by the organisms mentioned above, in
order to supply well-being to inhabitants
and, the need to develop innovative projects involving new treatment strategies and
remediation technologies that can be ex-
pensive but may be trivial compared with
potential health- care costs. This work also
mention that social concience about health
risks and consequences of environmental
circumstances have to be developed and the
actual situation must be taken into account
by authorities to achieve a final and definite
solution for this old problem.
65. A review of suitable technologies for
treatment of waters contaminated with
arsenic in Mexico
Héctor M. Poggi-Varaldo1; Carlos LuchoConstantino1,2; Luz María Del Razo3; Abigail
Pimentel1; Noemí Rinderknecht-Seijas4
1
Cinvestav-IPN, Dept. Biotechnology and Bioengineering, Environmental Biotechnology R&D
Group, México D.F. México
2
UTTT, Dept. Environmental Technology, Tepeji, Hgo., Mexico
3
Cinvestav-IPN, Toxicology, México D.F.,
México.4 ESIQIE-IPN, Division Basic Sciences,
México D.F., México
In México, several regions have been identified whose communities rely on fossil
groundwater contaminated with inorganic
Arsenic (iAs) for drinking water supply.
There is a pressing need for supplying
treated, low iAs drinking water to hundreds
of thousand people in our country. Then, the
objective of this review is to critically evaluate the most feasible modern technologies of
water treatment that could comply with the
WHO limit for As (< 10 µg L-1) and to identify a few niches of further research and
development adapted to the needs of Mexico.
The chemical speciation of iAs is crucial for
the treatment of polluted waters. The iAs can
exist as tri- and pentavalent species. The
speciation and predominance of the species
mainly depend on the pH. Arsenic removal
is favoured when the chemical species has
negative charges, thus, some type of preoxidation of iAs(III) to iAs(V) is generally
required for all the available technologies.
56
So, the fist step of treatment generally is
the preoxidation. Chlorine, hypochlorites,
ozone, permanganate, and a few patented
chemicals are recognized to be effective
oxidants for iAs. On the other hand, chlorine dioxide, chloramines, UV light alone
are not as effective. The combined photochemical oxidation consisting of UV light
with sulfite seems to be a promising alternative.
Traditionally, the iAs removal technologies
can be grouped in three categories: adsorption, membrane, and precipitation / coagulation-flocculation treatments. Several electro-technologies under development seem
to fall in the third category. The adsorption
of iAs by using ionic exchange resins and
zeolites is well established. Yet, it does not
remove iAs(III) at the working pH; high
iAs concentration can suddenly appear in
the effluent; the presence of sulfate and
other anions in the water can deteriorate the
process performance; liquid wastes are
produced by regeneration of the resin; and
poisoning and fouling of the resin lead to
costly resin replacement. The adsorption
using activated alumina does not remove
arsenite; it usually requires pH preadjustment; an aggressive liquid waste is
generated in each regeneration cycle; the
medium has to be replaced in the mid-term
due to solubilization of the alumina in the
regeneration cycles. The adsorption can be
also carried out using iron oxide media.
Regarding the removal of iAs by membrane
processes, the reverse osmosis (RO) is the
standard treatment. It can remove high
amounts of iAs(V) and considerable
amounts of iAs(III) as well. However, the
fouling of the membranes may lead to shutdowns and generation of liquid wastes; it is
energy-intensive because of the high pressure pumps.
The processes based on precipitation and
coagulation-flocculation are increasingly
becoming less favoured, since the conditioning-handling-and-disposal of the phys-
chem hazardous sludges is cumbersome and
expensive.
As a common denominator, all the currently
available technologies are expensive for
underdeveloped countries. Moreover, very
often the treatment selection depends on the
water characteristics other than that the mere
iAs concentration. Our future work seems to
revolve around two axes (i) adapting the
existing technologies for making them more
simple and cost-effective; or (ii) to find and
develop a technological breakthrough. It is
foreseen that the most feasible niches for
short-term R&D regarding iAs removal from
drinking water in Mexico are: (i) development of patent-free, hybrid or new adsorptive media; (ii) optimization studies on design and operation of RO for minimizing the
energy and maintenance requirements; (iii)
development of patent-free RO membranes
that can work at lower pressures and are
more resistant to fouling; (iv) coupling solar
energy to RO for minimizing costs associated to the energy of pumping; (v) last, but
foremost, any strategy of supplying drinking
water with low concentration of iAs should
be implemented together with effective and
strong programs of water conservation and
reuse. This is the only feasible approach to a
cost-effective, low-iAs drinking water supply.
66. Irrigation strategy in the context of
arsenic threat in Nepal
Bandana Pradhan
Department of Community Medicine and Family
Health, Institute of Medicine, Tribhuvan University, Kathmandu Nepal;
[email protected]
Arsenic contamination in groundwater and
the threat it poses to human health is relatively new for Nepal. Groundwater is the
main source of drinking and irrigation water
for the people living in the country’s southern part called Tarai region, a contiguous
part of the Indian Gangetic plain, where the
57
number of Arsenic risk population has increased during the last few years. Arsenic
studies carried out in 29,953 tube wells in
the Tarai region have shown that 32 percent
tube wells have Arsenic level above the
WHO Guidelines (10 µg L-1) and 7 percent
above the Nepal interim standard (50 µg L1
). Further, about 500,000 people living in
the Tarai are estimated at risk of Arsenic
problem.
The Tarai is the principal region for
potential agricultural development of
Nepal, where groundwater is the most
potential source for irrigation development.
His Majesty’s Government of Nepal has
recently taken significant initiatives for the
exploitation of groundwater in order to
increase the production of agricultural
crops. If irrigation is relied completely on
the groundwater, there is high chance that
arsenic may turn out to be disastrous in the
future. This situation needs to be taken very
seriously and ways and means need to be
devised to deal with the Arsenic threat in
implementing the government irrigation
strategy for agriculture intensification
through year round irrigation.
From the irrigation perspective, there is no
study conducted in Nepal to explore uptake
of Arsenic by different crops from irrigation water. Nevertheless, studies conducted
elsewhere in the world demonstrate that
uptake of Arsenic by a variety of vegetables and cereals that can get into the food
chain and ultimately affect the human
health. Scientists have argued that the
groundwater abstraction from Arsenic-rich
aquifers generates water fluctuation and
also accelerates weathering process of Arsenic-rich rocks and therefore creates conducive environment for Arsenic to be released and dissolved in water. If this hypothesis is true, mining of groundwater in
the Tarai region of Nepal will increase the
Arsenic content and thus will worsen the
existing situation.
This study intends to relate water availability
in the Narayani irrigation command area and
the arsenic contamination in groundwater in
four districts of the central Tarai region,
based on the thorough review of the existing
studies on arsenic contamination and identifies areas for better management for surface
water resources through modern irrigation
system. The findings of the study have revealed that the Arsenic level is high in areas
where there is low availability of surface
irrigation water and vice versa. Though the
analysis needs to be further verified through
more investigations, it is assumed that the
Arsenic level can be reduced by improving
the performance of surface irrigation delivery or less dependency on groundwater or
adopting arsenic removal strategy.
67. Arsenico: Evaluación, contaminacion,
especiacion; Su incidencia ambiental en la
cuenca del Altiplano Boliviano y la ciudad
de Oruro
Jorge Quintanilla1, Ramos Oswaldo1,
Medina Hugo2
1
Instituto de Investigaciones Químicas,
Universidad Mayor de San Andrés, La Paz,
Bolivia
2
Instituto Nacional de Salud Ocupacional
(INSO-SNS), La Paz, Bolivia
Varios trabajos se realizaron en el Altiplano
boliviano basados principalmente en la determinación de los parámetros fisicoquímicos de aguas superficiales (estado y calidad) fuentes de contaminación natural y
antrópica. Fundamentalmente en este trabajo
trata del arsénico contaminante natural,
evaluación de su distribución, modelación
geoquímica para determinar su naturaleza
primaria y su especiación teórica.
Estudios en aguas superficiales determinaron
las fuentes naturales y antropogénicas como
medios para el aporte significativo de
arsénico. Los estudios del Plan Piloto Oruro
(PPO, 1997) en la cuenca de los lagos
58
Poopó, han permitido establecer el origen
de la contaminación natural de los metales
pesados, concluyendo que el 85% del arsénico transportado por el agua superficial al
lago Poopó tiene origen natural, en el intemperismo de vulcanitas del Mioceno en
la cuenca colectora del río Mauri y de las
vulcanitas del Mioceno tardío/Plioceno en
la meseta de Los Frailes, en las cuencas
colectoras de los ríos Sevaruyo y Marquez.
La contribución de arsénico debida a las
minas y al procesamiento de minerales, es
poco significativa.
Otros estudios en la cuenca de los lagos
Poopó y Uru Uru realizados por la Universidad Mayor de San Andrés (UMSA-IIQ,
2004), indican que las aguas superficiales
con y sin actividad minera, en su mayoría
se encuentran por encima de los límites
permisibles para cualquier consumo (50
µg/L) y puede utilizarse para riego con
restricciones, según la Ley de Medio Ambiente de Bolivia Nº 1333, salvo alguna
excepción como el río Huaya Pajchi (vertiente Huari) muestra valores que están por
debajo de los limites permisibles para
cualquier uso. Los puntos ubicados en el
lago Poopó (sur, centro y norte) y Uru Uru
presentan valores que elevadas concentraciones de arsénico que las hacen no aptas
para ningún uso.
En general en el altiplano boliviano, las
aguas subterráneas de las cuencas del lago
Poopó y Uru-Uru (PPO, 1997) y del salar
de Uyuni presentan poca evidencia de
cualquier contaminación relacionada con la
actividad minera. Sin embargo, en la escala
local, las concentraciones de antimonio,
arsénico y cadmio son mucho más elevadas
en los sitios impactados que en los sitios de
referencia.
Para ésta evaluación se utilizaron datos de
trabajos anteriores (Quintanilla, 1992) que
permitió realizar la modelización, usando el
modelo geoquímico CHIMERE, lo cual
permitió determinar las especies secundarias y sus concentraciones al equilibrio,
derivadas del arsénico, que muestra predominancia en cinco especies secundarias
“mayoritarias” en condiciones reales de pH,
presión atmosférica y temperatura, cuya
distribución es AsO3-4 (32%), H2AsO-4
(22%), HAsO-4 (16.5%), As2O5 (17%),
H3AsO-4 (6%) y otros (6.5%).
Además, se cuantifico su incidencia, riesgo
ambiental y humano a través del control
toxicológico en la ciudad de Oruro (fundiciones de Vinto y Peró), en el año 1993, de
201 trabajadores sometidos al control toxicológico de arsénico en orina, el 32% presentaron niveles anormales de arsénico; en
1994, 120 trabajadores fueron sometidos a
control médico y se detectó que el 28,5%
presentaban niveles anormales de arsénico y
a fines del mismo año y como seguimiento
preventivo, fueron sometidos al control 199
trabajadores, habiéndose establecido que el
63,3% presentaban índices por encima los
máximos permisibles para indicadores
biológicos.
A objeto de compatibilizar los valores de
arsénico en orina, con muestras de arsénico
en aire, en diferentes puestos de trabajo se
determinó, que el 50% de las evaluaciones
en higiene industrial, en las áreas de hornos
los índices detectados se encontraban por
encima los máximos permisibles establecidos por la Conferencia de Higienistas
Americanos.
59
68. Arsenic assimilation into edible
plants grown in homestead garden soil
irrigated with arsenic laden groundwater
I.M.M. Rahman*a, M. Nazim Uddina, M.T.
Hasana, M. Helal Uddina, M.M. Hossainb and
M.A.U. Mridhac
intake of arsenic from the plants in the study
area was estimated to be 14.69 µg day-1.
Correlation with the groundwater arsenic
status and statistical significance of variations has also been determined.
a
Applied Research Laboratory, Department of
Chemistry, University of Chittagong, Chittagong-4331, Bangladesh;
[email protected]
b
Institute of Forestry and Environmental Sciences, University of Chittagong, Chittagong4331, Bangladesh.
c
Department of Botany, University of Chittagong, Chittagong-4331, Bangladesh.
One of the most important global environmental toxicants is arsenic whose high concentrations in groundwater have been reported from many countries. The arsenic
calamity of Bangladesh is the largest
known mass poisoning in the history, with
approximately 35–77 million people being
exposed to arsenic-contaminated drinking
water. Edible vegetables, medicinal and
aromatic plants grown in arsenic contaminated soil may uptake and accumulate significant amount of arsenic in their tissue.
The plants studied during the present investigation were Lablab niger (Bean), Lycopersicon esculentum (Tomato), Solanum
melongena (Brinjal), Cucurbita maxima
(Sweet gourd), Amaranthus gangeticus
(Red amaranth), Carica papaya (Green
papaya), Capsicum sp. (Chilli), Lagenaria
siceraria (Bottle gourd), Momordica charantia (Bitter gourd), Mentha viridis (Mint),
Vigna sesquipedalis (String bean), Abelmoschus esculentus (Okra), Trichosanthes
dioica (Palwal), Basella alba (Indian spinach). Mean arsenic concentration in the
selected plants in the area studied was
0.113 µg g-1. The minimum was found in T.
dioica (0.026 µg g-1) and the maximum in
M. viridis (0.566 µg g-1) followed by V.
sesquipedalis, Capsicum sp. (0.400, 0.200
µg g-1, respectively) while arsenic content
in A. esculentus, B. alba and C. papaya was
below detectable limit. The average dietary
69. Arsenic in surface and ground waters
of the Ghazipur and Ballia in the Central
Gangetic Plain of Uttar Pradesh, India
AL. Ramanathan1*, Prosun Bhattacharya2 ,P,
Tripathi1 and Manish Kumar1
1
School of Environmental Sciences, Jawaharlal
Nehru University, New Delhi-110067, India;
[email protected]
2
Resources Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
In the Holocene aquifers of the Indo-Gangetic plains of the states of Uttar Pradesh,
Bihar and Jharkhand elevated concentrations
of arsenic (As) have been reported in
groundwaters. The present paper reports
about the As and related contamination in
groundwater and surface water in two district of Gangetic plain in northern India.
Groundwater samples and surface water
samples were collected from a 2 km stretch
in the flood plain of the two rivers Ganga
and Ghagra river over a three year period in
Ballia and for one year in Ghazipur. The
water samples were collected from surface,
shallow and deep aquifers and analyzed for
other hydrogeochemical parameters including major anions and cations, and dissolved
trace elements.
Arsenic concentration in Ballia varies from
below detection limit up to as high as 80 µg
L-1. The concentration of As was very high
in the location close to the river basin. The
concentration of As near an inland lake was
also very high. Concentration of As were
found to be moderate to low in the interior
flood plains between these two basins. The
surface water showed high concentration
near the confluence of the two rivers. The
60
Ghagra seems to contributing more As. The
groundwater in the intermediate and deeper
aquifers has more As compared to As in
Shallow aquifers. In the Ghazipur the it is
observed that As concentration in ground
water is very low in most places expect few
locations where it exceed 30 µg L-1, where
as the surface water As concentrations is
very low. The correlation between Fe and
As was low. The sulphate concentration in
groundwater was low as compared to surface waters. These aquifers seem to be particularly in risk, due to the prevailing geochemical conditions in which oxidized and
reduced waters mix, and where the amount
of sulphate available for microbial reduction seem to be limited. The study needs
further refinement and the detailed work is
under progress to understand the processes
controlling the As concentration in surface
and ground waters.
70. Arsenic remediation from groundwater by environmentally reactive iron
nano particles
Sushil Raj Kanel* and Heechul Choi
Environmental Nano Particle Laboratory, Department of Environmental Science and Engineering, Gwangju Institute of Science and
Technology (GIST), Oryong-dong Bukgu, 500712 Gwangju, The Republic of Korea; *
[email protected]
It is well established that removal of Arsenic (As) is the major environmental concern due to its existence in groundwater
and acute toxicity. Many different methods
including precipitation-coagulation, co-precipitation, ion exchange, electro-coagulation, oxidation and adsorption are being
used for its remediation. Among them, the
adsorption method has received more attention due to its high efficiency and costeffectiveness, and considered as the most
suitable technology in the developing countries.
Among different types of adsorbents being
used for As remediation, zero-valent iron
nano particle (INP) is one of the most common because its capacity to remove both
As(III) and As(V) simultaneously. Providentially, recent study shows that INP has
shown great promise for environmental application. Due to the extremely small particle
size, large surface area, and high in-situ reactivity, these materials have great potential
in a wide array of environmental applications such as soil, sediment and groundwater
remediation. In addition, due to small size
and capacity to remain in suspension, INP
can be transported effectively by groundwater and can be injected as sub colloidal metal
particles into contaminated soils, sediments,
and aquifers.
In this perspective we have utilized for the
first time Environmental Iron Nano Particle
(E-INP) for the remediation of As. For
which we synthesized in laboratory E-INP
and tested for the removal of As(III). We
used SEM-EDX, AFM, and XRD to characterize particle size, surface morphology, and
corrosion layers formed on pristine E-INP
and As(III)-treated E-INP. AFM results
showed that particle size ranged from 1 to
120 nm. XRD and SEM results revealed that
E-INP gradually converted to magnetite /
maghemite corrosion products mixed with
lepidocrocite over 60 d. Arsenic(III) adsorption kinetics were rapid and occurred on a
scale of minutes following a pseudo-firstorder rate expression with observed reaction
rate constants (kobs) of 0.07-1.3 min-1 (at
varied E-INP concentration). These values
are about 1000?higher than kobs literature
values for As(III) adsorption on micron size
ZVI. Batch experiments were performed to
determine the feasibility of E-INP as an adsorbent for As(III) treatment in groundwater
as affected by initial As(III) concentration
and pH (pH 3-12). The maximum As(III)
adsorption capacity in batch experiments
calculated by Freundlich adsorption isotherm
was 3.5 mg of As(III)/g of E-INP. Laser
light scattering (electrophoretic mobility
61
measurement) confirmed E-INP-As(III)
inner-sphere surface complexation. The
effects of competing anions showed HCO3-,
H4SiO40, and H2PO42- are potential interferences in the As(III) adsorption reaction.
Our results suggest that E-INP is a suitable
candidate for both in-situ and ex-situ
groundwater treatment due to its high reactivity.
71. Arsenic crisis in Nepal: Key issues
and remediation
Prakash Raj Kannel1, Sushil Raj Kanel2, Sabina
Kanel3
1
Water and Remediation Research Center, Korea Institute of Science and Technology, PO
Box 131, Cheongryang, Seoul 130-650, South
Korea; [email protected]
2
Department of Environmental Science and
Engineering, Gwangju Institute of Science
and Technology (GIST), 1 Oryong-dong,
Buk-gu, Gwangju 500-712, South Korea;
[email protected]
3
Social Welfare Council Nepal, GPO Box
10907, Kathmandu, Nepal;
[email protected]
Groundwater is a significant source of
drinking water in many parts of the world
as well-protected groundwater is safer in
terms of microbiological quality than water
from open dug wells and ponds. Unfortunately, water is a universal solvent and
hence groundwater is notoriously prone to
chemical and other types of contaminations
from natural sources and anthropogenic
activities. The presence of unwanted contaminants in water makes it unacceptable to
drink for humans from both an aesthetic
and a health aspect, and can have severe
implications for all life forms. One of the
substances that water can dissolve is
chemical combination of the element “arsenic”.
The arsenic contamination is becoming
worldwide concern due to its high toxicity
and carcinogenic effect. Arsenic has long
been known as a poison and is best known
for its harmful acute and chronic effects.
Due to long exposer about ten to twenty
years, it ultimately leads to cancer. Arsenic
in drinking water has been detected in many
countries at concentrations greater than the
WHO guideline value of 10 µg L-1 or the
prevailing national standards. These include
Argentina, Australia, Bangladesh, Chile,
China, Hungary, Mexico, Peru, the United
States of America, Thailand, Myanmar and
Nepal. Among them, the arsenic crisis in
Bangladesh has been described as one of the
worst cases of mass poisoning in the world
history. Arsenic occurrence in groundwater
in Gangetic plains of Bengal Delta Plains of
Bangladesh, West Bengal of India is the
largest environmental health disaster areas of
the present century, where at least 50 million
people is at risk of cancer and other arsenic
related diseases due to the consumption of
high arsenic contaminated groundwater. The
levels of arsenic in the groundwater on these
areas are greater than the WHO guideline
and have been shown to cause adverse
chronic health effects.
Recently arsenic contamination of the
groundwater has been detected in Nepal
above 50 µg L-1 when arsenic testing was
undertaken realizing that it shares some geological features with the Gangetic plains of
India and Bangladesh. It is suspected that the
groundwater should have been contaminated
by natural arsenic source as the districts of
the Terai region is the area forming the
northern extension of the Indo-Gangetic
Plain and is composed of alluvial soil. In
such context millions of Nepalese are at risk
from diseases caused by drinking water contaminated with the poison arsenic. The problem is affecting the Terai lowlands, home to
47 percent of Nepal's 26 million people.
People are suffering from skin and other
serious diseases due to drinking underground
water laced with arsenic. It is estimated from
the studies that about 3.19 million people
may have been affected by arsenic contamination in Nepal.
62
To tackle arsenic problem, several milestones have been achieved in the three
years period in at the national level. One of
the significant achievement on this issue is
the formation of National Arsenic Steering
Committee (NASC)) for better coordination among the concerned agencies
which has formulated a national and a
working guideline for all interested concerned agencies. Presently, different options are tried for arsenic removal process
to the affected households and communities
of Nepal. Low cost, effective and socially
acceptable systems are still to be investigated. In addition, sufficient public awareness is still to be raised about the arsenic
hazards in Nepal.
72. Arsenite induces cytokeratin expression in mouse liver
P. Ramirez1, Oscar Zuñiga1, Mirna Hernández1
Valeria Berdón3, M. Cerbon2 and M. E. Gonsebatt3
1
Laboratorio de Toxicología Celular, FES
Cuautitlán
2
Laboratorio de Biología Molecular, Facultad
de Química, UNAM, México, DF.
3
Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones
Biomédicas, UNAM, México, DF.
Cytokeratins (CK) constitute a family of
cytoskeletal intermediate filament (IF) proteins that are typically expressed in epithelial cells. In simple type epithelia such as
liver, exocrine pancreas and intestine the
two major IF proteins are CK polypeptides
8 and 18. Increased levels of CK18 are
observed in human liver disease such as
primary billiary cirrhosis and in alcoholic
liver disease, related to Mallory body formation as a consequence of CK accumulation. Modified synthesis and abnormal organization of these intermediate filaments
are considered indicators of liver damage.
The liver is also the main organ where
many carcinogens such as arsenic are metabolized. Studies in humans exposed to
inorganic arsenic by the oral route have
noted signs or symptoms of liver injury.
Also, lipid vacuolation and fibrosis have
been reported in rats exposed to arsenic in
drinking water. Increased synthesis and disruption of CK 18 cellular organization, have
been induced in WRL-68 human fetal hepatic cell line by sodium arsenite. In this
work, male BALB/c mice were given orally
2.5, 5 and 10 mg kg-1 per day of sodium
arsenite. CK expression was monitored in
liver after 2 and 9 days. Significant induction
of CK18 mRNA and protein synthesis were
observed in those animals exposed to the
lower doses when liver samples were examined by RT-PCR and Western blotting respectively. We did not observe significant
induction at the highest dose employed, suggesting that arsenite is inhibiting the synthesis of this important protein to hepatocyte
architecture. The induction of CK 18 could
be considered as an early indicator of liver
damage by arsenic. This work was partially
supported by PAPIIT IX201004 and
CONACYT I38967-N.
73. Effects of arsenic and fluoride on the
central nervous system
Rocha-Amador D. O.1, Carrizales Yañez L.1,
Morales V. R.2, Navarro C. M.E.2, Calderón H. J.1
1
Facultad de Medicina de la Universidad
Autónoma de San Luis Potosí
2
Facultad de Psicología de la Universidad
Autónoma de San Luis Potosí
Million of people around the world are exposed to arsenic (As) and/or fluoride (F)
through drinking water (DW). In Mexico,
approximately 6 million of people are exposed to both pollutants; from these 35% are
children. Experimental and epidemiological
studies, supports the evidence that both pollutants are neurotoxic. They have the ability
to cross the blood brain barrier and to accumulate in the brain. Nevertheless, one of the
worrisome effects is the reduction of the
intelligence quotient (IQ). In the center-north
63
of Mexico the As and F levels in DW are
superior to the established values in the
Norma Oficial Mexicana (NOM SSA1027). We designed a cross-sectional study
in children, to evaluate the effect of the
exposure to As and the F on the IQ and the
neurological functions in children. Onehundred thirty two children from 6 to 10
years were included in the study from four
communities with different As and F concentrations in DW: 1) Soledad de Graciano
Sánchez, San Luis Potosí, (SLP) (As 6.7 ±
1.2 µg L-1; F 0.7 ± 0.3 mg L-1); 2) Moctezuma, SLP (As 4.5 ± 1.5 µg L-1; F 1.1 ±
0.01 mg L-1); 3) Salitral de Carrera, Villa
de Ramos, SLP (As 169.5 ± 16 µg L-1; F
5.3 ± 0.18 mg L-1 and 4) 5 de Febrero, Durango (Dgo) (As 200 ± 84 µg L-1; F 9.4 ±
1.1 mg L-1). Two neuropsychological tests
were applied; 1) The Weschler Intelligence
Scale revised version for Mexican children
(WISC-RM) to evaluate, the IQ (verbal,
performance and full), as well as cognitive
functions (like attention, memory, visuospatial organization and language), and 2)
The Rey-Osterrieth Complex Figure Test
(ROCF), to evaluate visuospatial organization and short term memory. As exposure
biomarkers As and F in urine were analyzed by atomic absorption spectrophotometry. As confounding factors lead in
blood (PbS), socioeconomic status (SES)
and nutritional evaluation (anthropometric
measurements and iron deficiency) were
evaluated. After adjusting by confounding
factors, inverse associations between As
and the F in urine and the scores of Full IQ,
verbal IQ, performance IQ and the ROCF
were obtained. These results suggest that
the chronic exposure to both pollutants
affects the higher brain functions in these
children.
74. As behavior in an urban aquifer:
Chemical, geological and hydrogeological
characterization
R. Rodriguez, E. Mata and J.A. Mejia
Geophysics Institute, UNAM, Mexico
COTAS, Irapuato valle de Santiago, Mexico
Salamanca is an industrial city where a Petrochemical Plant and chemical industries are
established. The urban area is crossed by the
Lerma River. In most of 80% of the urban
wells As was detected. The As concentrations are 0.01 to 0.07 mg L-1. Population is
been exposed to low, but constant, As concentrations. There are not evidences of
health affectations.
Some urban wells are located inside the urban area, around the industrial zone. The
high As concentrations allow the closure of
3 wells. In 2 of them, was detected also hydrocarbons. There is not a clear correlation
between free phase and As content in
groundwater.
A hydrochemical, geological and hydrogeological characterization is been realized
in order to clarify the origin and factors that
control the As mobility.
The aquifer system is composed by sedimentary and volcanic rocks, in both environments As was detected. The main recharge
mechanism is associated to rainfall infiltrations in the Guanajuato range. A regional
flow component was inferred to the north
were the As concentrations are very low.
The preliminary results show that fault, fractures and paleochannels are controlling the
As distribution in a shallow aquifer unit. The
origin is mainly natural but there are evidences that there are also anthropogenic
sources.
64
75. Arsenic in drinking water in Córdoba Province, Argentina
G. Román-Ross1, G. Sacchi2, L. Charlet3, M.
Avena4, and C. Pauli2
1
Department of Chemistry, Faculty of Sciences,
University of Girona, Campus de Montilivi, E17071 Girona, Spain; [email protected]
2
Facultad de Ciencias Químicas, Universidad
Nacional de Córdoba, Ciudad Universitaria,
5000 Córdoba, Argentina
3
LGIT-OSUG, Université Joseph Fourier, BP
53, F-38041 Grenoble Cedex 9, France
4
Departamento de Química, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahía
Blanca, Argentina
Arsenic in drinking water can impact human health and is considered one of the
prominent environmental causes of cancer
mortality in the world. Latin America is
among the most affected areas worldwide.
As opposed to the now well studied Bangladesh case, arsenic contaminated waters in
Argentina are well oxygenated waters. Arsenic affects mainly rural population, which
is exposed to arsenic levels of around 5.3
mg L-1 in the most contaminated areas. At
present, epidemiological studies are scarce
due to the lack of Cancer Registries and to
exposure heterogeneity. In Argentina, national and local governments do not have
the responsibility for providing safe drinking water. Each small local water company
is responsible for the quality of the supplied
water. In addition, only few local laboratories are able to provide quality control arsenic analyses. The current Argentinean As
guideline has been set up equal to 50 µg L-1.
However, this guideline can be considered
as a temporary measure due to the increasing international efforts to lower this limit
down to 10 µg L-1. The estimated costs of
compliance with more stringent standards
are high. In this context, it is worthwhile to
examine the arsenic contamination on the
basis of these different possible guidelines.
In the present study we analysed drinking
water supplied by local companies in the
Cordoba Province. The As-contaminated
waters in this region are in contact with
loess, a thick sequence (generally around
200-300 m) of Tertiary and Quaternary
sediments. Borehole depth is highly variable
depending on the regional topography. In the
western area, where loess deposits are extremely thick and groundwaters rather deep,
it may be as deep as 140 m below ground
level. In the eastern area wells are shallow,
as groundwater level is closer to the surface,
and wells depth is typically 10 m or less. In
the major towns, groundwater is treated by
reverse osmosis to remove dissolved salts
and As before to be delivered as drinking
water. In the rural areas, this is not possible
and water is typically used without pretreatment, and is thus often arseniccontaminated. We have collected and analyzed arsenic as well as V, F, U, Se, in drinking water from 200 cities and villages across
Cordoba Province, during 2004. The number
of samples, broad geographic coverage, and
consistency of methods produce the most
accurate and detailed picture of arsenic concentrations in drinking water for the region.
Maps of the contamination have been produced to show the hotspots and the factors
affecting the presence of arsenic (borehole
depth, water treatments, etc). Most rivers and
streams in Córdoba province contain arsenic
concentrations ≤1 µg L-1. Therefore, towns
and cities that use this water as source are
free of As contamination. In contrast, waters
from heavily impacted areas in the E and S
exceed the As limit (50 µg L-1). This data
contribute to the understanding of the status
and trends of arsenic concentrations in drinking water in Córdoba Province, and can: (1)
assist water managers and users in overcoming adverse health effects through avoidance
or treatment; (2) provide a basis for evaluating the costs of adopting a particular value
for a drinking-water standard; and (3) assist
epidemiologists interested in evaluating the
intake of arsenic from drinking water.
65
76. Arsenic in loess and volcanic ashes of
Cordoba Province, Argentina
G. Roman-Ross1, Laurent Charlet2 and Diego
Gaiero3
1
Dept. of Chemistry, Faculty of Sciences, University of Girona, Campus de Montilivi,
17071 Girona, Spain; [email protected]
2
LGIT-OSUG, Université Joseph Fourier, BP
53, F-38041 Grenoble Cedex 9, France
3
CIGeS- FCEFyN, Universidad Nacional de
Córdoba, Pabellón Geología, Avda. Velez Sarsfield 1611. X5016GCA Córdoba, Argentina
The main objective of this study was to
explore whether iron oxides or volcanic
ashes are the main arsenic storage material
in the sedimentary aquifers of the Cordoba
Province, Argentina.
Loess samples were collected from two 14
and 7 m thick natural outcrops. One profile
is located in the western region, and the
second one in the eastern part of Cordoba
province where groundwaters have the highest As concentrations. Identification and
separation of volcanic ashes from loess outcrops is difficult to perform and little
amount can be obtained from loess samples
to perform laboratory studies. Therefore, we
sampled volcanic ashes from a sedimentary
lacustrine core which has yielded a continuous record of particles deposited over the
last 15.0 kyr BP.
Total concentration of As in volcanic ashes
samples varies from 5 to 20 mg kg-1. Although volcanic ashes represent only a tiny
fraction of loess material, the same concentration range has been measured in loess
materials. Furthermore, the percentage of
As linked to the different phases as determined by selective extractions is nearly
constant both in loess and volcanic ashes
sampled in the lake core. Ionically bounded
As is very rare (2% of total As). In Argentinian loess, secondary carbonates are
abundant as nodules, layers or cements and
secondary Mn oxide is also present as nodules in some horizons. Arsenic found in the
corresponding fraction represents 18% of
total arsenic in loess samples and 22% in
volcanic ashes. A special attention was given
to Fe oxides since these minerals have been
cited in the literature as being the main
source of As in Pampean aquifers. Selective
extractions performed on volcanic ashes and
loess samples show that As is mainly associated to Fe oxides (around 60% of extracted
As).
These studies were complemented by incubation experiments to investigate As desorption under conditions prevailing during
flooding periods, i.e. desorption induced
either by excess of bicarbonate ions or by
reducing conditions. The quantity of As release in oxic waters is equal to 100 µg L-1
and increase linearly up to 300 µg L-1 in
presence of increasing bicarbonate ion concentrations. Therefore, bicarbonate leaching
is presumed to be one important mechanism
to mobilize arsenic in bicarbonate dominated
oxidizing aquifer of the region.
In Córdoba Province, recent variations in the
hydrological budget have lead dry and wet
intervals that resulted in distinctive fluctuations of lake levels, river discharges and
recurrent floods of very productive soils in
the low plain. This shift in aeration status of
the soils lead to the reduction of As(V) reduction to As(III), a more mobile and toxic
species. Leacheable As(III) concentrations in
anoxic conditions may increase up to 400 µg
L-1.
77. Sources and transport of arsenic contaminating shallow groundwater in the
historical industrial zone of Monterrey
City, Nuevo León, México
Francisco Martín Romero, Margarita Gutiérrez
Ruiz and Mario Villalobos
Instituto de Geografía, UNAM-México, Mexico;
[email protected]
Arsenic contamination has been detected in a
shallow aquifer of the geographical center of
66
Monterrey City, in the Northeast of Mexico, and where the historical industrial zone
of the city is located, reaching concentrations of up to 3.1 mg L-1. A metallurgical
plant that operated more than 100 years and
closed down in 1999 is identified as a possible pollution source because it deposited
arsenic-rich wastes in the fields adjoining
it, showing total arsenic contents that reach
up to 1-2% As in weight. We deem arsenic
transport through the soil profile as highly
unlikely based on the following experimental and field evidence: water-soluble arsenic contents in 1:20 soil:water extracts of
both surface and subsurface samples is very
low, showing values in a majority of samples below 1 mg As L-1; the unsatured zone
under the inactive plant is characterized by
the presence of two impermeable clay layers (hydraulic conductivities of 2.1 x 10-8
cms-1 to 8.4 x 10-8 cms-1), the first one occurring at 0.6 to 1 m below the surface, and
the second one at approximately 17 m below the surface; arsenic analyses of several
core samples from boreholes 40 m deep
show that As released at the soil surface is
completely retained in the upper clay layer.
Nevertheless, the highest dissolved arsenic
concentrations (1.1 to 3.1 mg L-1) were
found in wells from shallow groundwater
from active industries located to the north
of the inactive plant. The groundwater flux
in the area goes in a direction west to east,
therefore, the source of these arsenic levels
cannot come from the inactive plant premises and indicates the occurrence of additional sources of arsenic groundwater contamination.
The evidence points to the fact that the
most likely cause of shallow groundwater
contamination inside the inactive plant is
via surface runoff of deposited wastes during the rainy season, into drilled boreholes
in the area. This is supported by a 10-year
semester analysis database, which shows a
constant seasonal variation in dissolved
arsenic concentrations measured at the
drilled boreholes, fluctuating between 0.1
and 0.9 mg L-1. Therefore, the authors recommend a suitable and immediate closure of
these boreholes.
78. Geogenic arsenic enrichment in histosols
Thomas R. Rüde1 and Henrietta Königskötter2
1
RWTH Aachen University, Institute of Hydrogeology, Aachen, Germany;
[email protected]
2
Ludwig-Maximilians-University Munich, Department of Earth and Environmental Sciences,
Munich, Germany; [email protected]
There is an increasing awareness of natural
arsenic enrichments in aquifers and overlying soils worldwide. In contrast to anthropogenic contaminated sites, these geogenic
enrichments occupy large areas and cause an
often unforeseen threat to humans. There are
now several reports in Germany of soils,
often histosols, which have very high arsenic
concentrations. The example discussed here
is an area in southeastern Germany with up
to 4000 mg kg-1 As.
There, soils are cultivated since approx. one
hundred years and it is discussed that arsenic
was enriched in the organic matter due to
cultivation. The process in mind is a dewatering of the organic rich horizons accompanied by shrinking and decomposition of
these horizons and enrichment of arsenic on
residual matter. Alternatively, arsenic can be
enriched on pedogenic iron and/or manganese oxides.
We tested both hypotheses on three profiles
which were studied in detail. The profiles
show organic rich layers on top with total
thicknesses of 0.25 to 0.55 m. The humic
horizons contain 15 to 35% of organic carbon. The lower parts of the profiles consist
of carbonaceous gravels with up to 70% of
calcite and only around 1% of organic carbon. These lower horizons show redoximorphic features and the lowermost horizon is
saturated by capillary fringe and groundwater. All profiles show concentrations of iron
of 5 to 8% in the humic layers which de-
67
crease sharply in the redoximorphic lower
layers to values of 1 – 2%. The second
uppermost horizon of one profile is a ferric
one with up to 30% of iron. Manganese is
only a minor constituent with concentrations around 1300 mg kg-1 in the humic and
approx. 150 mg kg-1 in the calcareous redoximorphic horizons. Sequential extractions demonstrate that pedogenic iron oxides are the dominant iron minerals especially in the humic horizons which make up
80% of iron as a maximum.
Arsenic concentrations in the profiles follow sharply the distribution of iron oxides
with a fraction of explained variance r2 =
0.914. Using total iron concentrations the
correlation is much weaker with r2 = 0.661.
There is now distinct relation of arsenic to
the organic carbon. We conclude from our
observations that arsenic is enriched on iron
oxides in the soils and that the organic carbon is only of minor importance.
The original source of the arsenic is probably a deeper aquifer with well known geogenic enrichment of arsenic. That aquifer
and the one covered by the soils are regionally connected by hydraulic windows
which allow for the transport of arsenic into
the upper one and enrichment of arsenic
during pedogenesis.
Actually, the mobile fraction of arsenic is
very small (less than 1% of the total concentration) which is proved by small water
soluble concentrations, low concentrations
in the groundwaters of the area and only a
few spots of increased arsenic concentrations in grass and crops. The risk is that the
pedogenic sink of arsenic will become dissolved during changes of land use especially renaturalization of bogs and wetlands.
79. Arsenic determination in soils from a
mining zone in the eastern Pyrenees,
Spain
M.J. Ruiz-Chancho, J.F. López-Sánchez, R.
Rubio
1
Departament de Química Analítica, Universitat
de Barcelona. Martí i Franqués 1, 3ª planta,
08028 Barcelona; [email protected]
The Vall de Ribes is situated in the Eastern
Pyrenees and at the beginning of this century; the now abandoned mining district
produced small amounts of several metals
like As, Sb, Au. Nowadays soils with high
contents of As can be found in this zone,
usually associated with the presence of arsenopyrite.
Seven soil samples were collected in three
differentiated sites of this mining zone, the
first sample point belongs to an old Sb mine,
the second one to an As and Sb mine and the
third one belongs to an old As mine. Soil
samples were air dried and sieved to 2 mm
and 90 µm. For these soil samples the mineralogical composition, pH, organic matter
estimation and major components were determined.
Total arsenic content was carried out in aqua
regia extracts by ICP-AES and HG-AFS. For
the species extraction a mixture of phosphoric and ascorbic acid was used and the determination of arsenic species was performed by using the coupled technique
HPLC-HG-AFS.
High levels of arsenic were found in some
samples ranging from 51 to 38000 mg kg-1
and with the only presence of inorganic arsenic (As(III) and As(V)) were detected
when the speciation analysis was performed.
68
80. Arsenic content in plant samples
from a mining contaminated area
M.J. Ruiz-Chancho, J.F. López-Sánchez, R.
Rubio
Centro de Estudios del Agua, Instituto
Tecnológico y de Estudios Superiores de
Monterrey; Av. Eugenio Garza Sada No. 2501
C.P. 64849, Monterrey, N.L., Mexico;
[email protected]
1
Departament de Química Analítica, Universitat de Barcelona. Martí i Franqués 1, 3ª planta,
08028 Barcelona; [email protected]
The Vall de Ribes, situated in the Eastern
Pyrenees in Spain, was one of the main
producers of iron at the end of the last century. It is also known the presence of As,
Sb, Cu. High levels of As were found in
soils of this zone in a range from 51 to
38000 mg kg-1. For this reason it was expected that plants growing on the contaminated zone could contain relatively high
concentrations of As. Arsenic present in
these plant samples in determined conditions could be bioavailable.
Several plant samples were collected in
seven contaminated sites. About 40 plant
samples of 20 different species were collected, cleaned with deionized water, dried
at 40ºC and finally crushed. Total content
of As was carried out by acid digestion in a
microwave oven and quantification was
performed by ICP-MS. Arsenic concentration in plant samples ranged from 0.1 to
5400 mg kg-1 depending on the sample
specie as well as the arsenic soil concentration. Uncontaminated terrestrial plants usually contain about 0.2 to 0.4 mg kg-1.
The arsenic species content was determined
in several samples by using coupled techniques as HPLC-(UV)-HG-AFS and
HPLC-ICP-MS. Several extraction media
were tested in order to obtain the best extraction efficiency and to preserve the
original species of the sample.
81. Identification of areas with major
arsenic concentration in the MeoquíDelicias aquifer, Chihuahua
Yadira Ruiz-Gonzalez, Jürgen Mahlknecht*
It is known that the groundwater of semiarid
Meoquí-Delicias area in Chihuahua, Northern Mexico, consisting of several municipalities (Saucillo, Rosales, Meoquí, Delicias
and Julimes), is affected by arsenic contamination. The present study deals about presence, distribution and plausible origin of
arsenic in the Meoquí-Delicias aquifer.
Of a total of 47 water samples from deep
tubewells of the Meoquí-Delicias aquifer,
68% demonstrate not to comply with the
maximum admissible value of the Mexican
Standard for drinking water (NORMA OFICIAL MEXICANA NOM-127-SSA1-1994;
0.025 mg L-1). A maximum value of 0.45 mg
L-1 has been observed in the area of Delicias
City, which is 17 times the maximum admissible value. This concentration represents a
major social risk for the inhabitants of this
city.
The tubewells with a major arsenic concentration generally lie very near of or in urbanized areas of the region: in the north of the
Meoquí city, in Delicias city, and south to
the Saucillo town; those municipalities represent the major population of the study area.
It is assumed that the origin of arsenic is
geologic, induced by heavy pumping of
groundwater resources.
82. Estimate of the current exposure to
total arsenic in Chile
Ana María Sancha
Department of Civil Engineering. Universidad de
Chile. P.O. Box 228/3; Santiago, Chile;
[email protected]
Exposure to arsenic in Chile results from
natural hydrogeochemical conditions and
from antropic sources derived from the mining activities carried out in some areas of the
69
country, mainly in the north and central
zone.The arsenic levels found in different
environments and the results of epidemiological studies indicate that this element
constitutes an important health risk factor,
principally for the inhabitants of the north
of Chile.
Current total arsenic “external” exposure
was assessed by combining data on the
levels of arsenic in water, food and air, with
information about food consumption, rates
of water ingestion and air inhalation. The
results showed that the population’s mean
level of exposure to total arsenic fluctuates
between 173.85 and 80.99 µg As day-1.
Ingestion of water was found to be the most
important exposure pathway for population
of northern and central Chile and for the
southern Chile the largest contribution corresponds to food. Air is not a significative
exposure pathway
A historical estimation of the total exposure
of the northern Chile indicates that in the
decade of the 70’s the arsenic exposure via
water became, in some cities as Antofagasta and Calama, ten times as high as it is
now. Exposure via air must have been
somewhat lower due to less intensive mining activity at that time. Exposure via food
may be considered similar or slightly
higher than the current one.
83. Arsenic removal from water with low
initial turbidity: Chilean experience
Ana María Sancha
Department of Civil Engineering. Universidad
de Chile. P.O. Box 228/3; Santiago, Chile;
[email protected]
This study presents Chilean experience in
arsenic removal from groundwater. Neither
the origin of arsenic in groundwater nor the
processes responsible for its mobility are
known with certainty, but it is suspected
that it is a naturally occurring contaminant.
The coagulation process has been used in
Chile since the 70’s to remove arsenic from
surface waters with high arsenic content.
Through previous studies, we know that in
the case of water with low arsenic content and
low turbidity, this process could be replaced
by a simplified treatment consisting of a direct coagulation-filtration process. This results in a significant cost reduction in investment, operation and maintenance costs.
Arsenic is removed through chemical sorption and particulate removal processes with a
previous oxidation and pH conditioning. The
addition of metallic coagulants facilitates the
conversion of inorganic arsenic species into
insoluble reaction products which are separated later on by means of filtration. Key
factors in arsenic removal by this simple and
low cost technology are: pH, oxidant and
coagulant dosage mixture speed, retention
times and filter washing frequency. During
the experimentation period the arsenic concentration in raw water ranged from 0.05 to
0.07 mg L-1 and the pH ranged from 7.0 to 9.0.
Good correlations exist between particulate
removal and arsenic removal. Treated water
with residual As <0.010 mg L-1 is obtained
during long operation periods.
84. Dietary arsenic and selenium intake
by school children in arsenic-endemic
areas of Argentina, Ecuador and Mexico
Luz C. Sanchez-Peña1, Silvia S. Farias2, Graciela
Bovi-Mitre3, Edda Villaamil4, Leticia GarciaRico5, Jenny Ruales6, Dinoraz Velez7, Rosa
Montoro7 and Luz M. Del Razo1
1
Toxicology-Cinvestav-IPN; Mexico City, Mexico
2
CNEA, Buenos Aires, Argentina
3
Ingenieria-UNJu, Jujuy, Argentina,
4
FFyB-UBA, Argentina,
5
CIAD, Sonora, Mexico,
6
IIT-EPN, Quito, Ecuado,
7
IATA, Valencia, España
Arsenic (As) occurrence in the aquifers of
several geographic regions such as Argentina, Ecuador and Mexico have been identi-
70
fied. Selenium (Se) is an essential micronutrient with a recommended dietary allowance for humans of 50 to 200 µg per day. It
functions as an essential constituent of selenoproteins. In the Andean regions of Ecuador, Se deficiency has been reported in
children. People in many other areas of the
world are selenium deficient, with the consequence that they are unable to express
their selenoproteins fully. As and Se are
metalloids with similar chemical properties
and metabolic fates.
The interactions between As y Se are complex. The toxic effects of inorganic Se can
be ameliorated by exposure to As. In contrast, inorganic As (iAs) potentiates the
toxicity of methylated Se compounds. The
metabolism, retention and toxicity of As
can be modified by exposure to Se. Because chronic exposure to As has been
associated with increased incidences of a
variety of cancers and increased risk of
morbidity or mortality due to peripheral
vascular, cardiovascular or cerebrovascular
disease, to hypertension or to diabetes mellitus, there is considerable interest in identifying factors that modify the susceptibility
of individuals to the toxic and carcinogenic
effects of As. For example, it has been suggested that differences among human populations chronically exposed to As in the
manifestations of the adverse effects of this
metalloid might be related to variation in
Se intake. Thus, it can be postulated that
individuals with a high intake of Se may be
less likely to suffer from a given toxic effect of chronic exposure to iAs than are
individuals with a lower intake of Se. Conversely, a lower intake of Se may exacerbate the toxic effects of As, increasing the
risk associated with chronic exposure to
this metalloid.
In order to estimate the intakes of total
arsenic, iAs and total Se concentrations,
food consumed by school children attending elementary school were evaluated. Four
schools whose communities rely on fossil
groundwater contaminated with As for
drinking water supply (> WHO limit of 10
µg L-1) were selected. The source of As contamination of the groundwater is the subsurface soil chemical composition and characteristics and not the anthropogenic activities.
School are sited in Santiago del Estero,
Argentina; Quito, Ecuador; Hermosillo and
Zimapan, Mexico.
Total As, iAs and total Se levels were measured by AAS. The dietary intakes of these
elements were determined by a total diet
study. Calculations were carried out on the
basis of recent data on the consumption of
the selected food items.
Information about Se intake in arsenicendemic areas will be useful information for
identification of factors that affect the toxic
effects of As exposure.
85. Exposure to arsenic: Modification of
cell proliferation and differentiation markers in primary human keratinocytes
M. Sandoval1, M. Corona1, Moisés A. Ortega, M.
Sordo2, P. Ostrosky2, E. Lopez-Bayghen1
1
Departamento de Genética y Biología
Molecular, CINVESTAV-IPN, 2Departamento de
Genética y Toxicología Ambiental, Instituto de
Investigaciones Biomédicas, UNAM, Mexico
D.F., Mexico
Human exposure to arsenic is associated
with an increased incidence of skin pathologies as hyperkeratosis and cancer. Different
mechanisms have been explored including
genotoxicity, cell proliferation changes, altered DNA repair or modifications in methylation patterns. The proliferation and differentiation of skin stratified epithelial cells
requires the coordinated expression of structural and regulatory proteins. All modifications in expression patterns of these proteins
result of special interest in arsenicassociated-skin pathologies. Here, we test if
during arsenic exposure, some changes in the
proliferation and differentiation process in
human keratinocytes can be mediated by
modifications in the expression levels of p53
71
and human involucrin (Hi). The tumour
suppressor p53 is a potent mediator of cellular responses against genotoxic damage,
controling normal cell proliferation and
may be a modifier of the differentiation
process in keratinocytes. The human involucrin (Hi) is an important differentiation
marker and estructural protein in cornified
envelope of terminally differentiated
keratinocytes. Based on this premise, we
treated human keratinocyte cultures (HKC)
with increasing concentrations of sodium
arsenite for up to 24 h. We evaluated the
effects of arsenic on cell proliferation,
genotoxic damage, and changes in Hi and
p53 protein levels. Likewise, we examine
the effect of arsenite on cyclin D1 protein
levels, as an indicator of regulation of cell
proliferation.
gel shift assays were performed using a p53consensus DNA-binding sequence. A dosedependent response in DNA binding can be
noticed under arsenic exposure. Using a
reporter system, in which, transcriptional
activity is mediated by a p53-driven-SV40
promoter, the augmentation in arsenic concentrations correlates with a higher transcriptional activity. Additional data support
the idea that signalling events as Protein
Kinase B activation may be important in p53
activation. Current work in evaluating sodium arsenite effect on p53-regulated genes
may result in important data to understand
modifications in the differentiation process,
via p53, which may be an important altered
pathway during skin carcinogenesis.
The arsenite effect on HKC was an increase
in proliferation, in cells under treatment
with a relatively low concentration
(0.1µM). This effect was companied by an
increase in cyclin D1 protein levels, when
cells are exposure at concentrations of arsenite less than 0.5 µM. Significantly, using
concentrations higher than 0.5µM, we noticed a decrease in proliferation and increased levels of Hi protein, supporting the
idea that arsenic may act as a differentiation inducer in our system. Exposure of
HKC to different concentrations of sodium
arsenite resulted in increased levels of p53
and Hi (in a dose-response manner). These
data indicate that sodium arsenite induces
an increase in p53 protein levels, probably
in response to DNA damage. Increment of
micronuclei counts in cells exposed to 1µM
of sodium arsenite for 24 hr, indicated a
significant cell damage associated with
exposure to arsenic.
86. Remediation of arsenic contaminated
waters by ferric iron and ferric compounds – a review
In order to understand the molecular
mechanisms underlying p53 role as modulator of gene expression controlling cell
proliferation, and even in the control of
keratinocyte differentiation, we tested if
arsenic may modulate the ability of p53 to
act as a transcription factor. Electrophoretic
Tony Sarvinder Singh* and K. K Pant
Department of Chemical Engineering, Indian
Institute of Technology,
Hauz Khas, Delhi 110016 INDIA; *:
[email protected]
Arsenic, a commonly occurring toxic metal
in natural ecosystem, is associated with either natural conditions or the industrial practices of mankind. Arsenic does not often
form in its elemental state and is far more
common in sulfides and sulfo salts such as
arsenopyrite, orpiment, realgar, lollingite and
tennantite whereas it readily substitutes for
silicon, ferric, iron and aluminium in crystal
lattices of silicate minerals. One of the two
distinct mechanisms that lead to the release
of arsenic on a large scale, is the development of high pH (>8.5) conditions in semiarid or arid environments usually as a result
of the combined effects of mineral weathering and high evaporation rates. This pH
change leads either to desorption of adsorbed
arsenic and a range of other anion-forming
elements from mineral oxides, especially
iron oxides. The second is the development
72
of strongly reducing conditions at nearneutral pH values, leading to the desorption
of As from mineral oxides and to the reductive dissolution of Fe and Mn oxides, also
leading to arsenic release. The process is
generally aided by the high water table and
fine-grained surface layers which impede
the penetration of air to the aquifer. Elevated concentrations of arsenic (> 1 mg L-1)
in groundwater of geochemical origins
have been found in many countries such as
Taiwan, India (West Bengal), Bangladesh,
Chile, North Mexico, Argentina, USA and
Nepal. Due to its various carcinogenic and
mutagenic effects on human and animals,
various regulatory agencies have prescribed
different permissible limits for arsenic such
as 0.01 mg L-1 (WHO).
Various technologies reported in the literature for the treatment of arsenic are conventional co-precipitation, lime softening, filtration, ion exchange, reverse osmosis and
membrane filtration but due to the excessive use of chemicals, bulky sludge, high
cost, these techniques are not cost effective
at small scale or household level. A thorough literature review revealed that adsorption has been extensively used for arsenic
removal. Some of the most common adsorbents tried for the removal of arsenic are
activated carbon, iron oxide, manganese
oxides, different polymeric materials and
alumina. In recent years, elemental and
zero valent iron has received considerable
attention as a media for treatment of wide
variety of contaminants in water such as
chlorinated hydrocarbons, chromium, nitrates and radionucides. One of the chief
advantages of using this media for treatment is its adaptability to passive flow
through application, which can be significantly less expansive to operate. This paper
is an effort to review the different kinds of
Iron and Iron based adsorbents used for
arsenic removal.
Several iron (II) oxides such as amorphous
hydrous ferric oxide (FeOOH), Hydrous
ferric oxide (poorly crystalline ferrihy-
drite), goethite, pyrite, hematite and green
rust (an intermediate product of iron oxidation that eventually transform to ferric oxyhydroxide) have shown promising results for
both As(V) and As(III) removal from aqueous solution.
Most of the Fe oxide shows strong sorption
affinity toward both As(V) and As(III)
through ligand exchange in the co ordination
sphere of structural Fe atom. Various investigation into the mechanism of arsenic removal revealed that As(III) and As(V) are
selectively bound to the oxide surfaces
through formation of inner sphere complex.
Electrostatic interaction and specific adsorption are also important mechanisms for arsenic removal by the iron oxides, which form a
passivation layer on Feo iron oxides including poorly crystalline oxide. As(III) is more
toxic and difficult to remove from aqueous
solution, Attempts have also been made to
impregnate this Fe metal/ion on basic material such as sand, clays to increase its sorption capacity. This paper discusses the adsorbent preparation techniques and the comparisons of Iron and Iron based adsorbents
with other sorbents have also been presented.
87. Effect of chloride, sulphate, phosphate
and fluoride ions and regeneration studies
on the sorption of arsenic by activated
alumina and Iron oxide impregnated activated alumina
Tony Sarvinder Singh* and K. K Pant
Department of Chemical Engineering, Indian
Institute of Technology, Hauz Khas New Delhi
110016, India; *: [email protected]
Numerous studies regarding the sorption of
arsenic have been reported in the literature
where different kinds of adsorbents such as
Activated Carbon, Iron and Manganese
based adsorbents, Lanthanum based adsorbents have been used. In most of these studies, synthetic solutions (arsenic solution
prepared in distilled water) have been used
73
whereas in real ground or surface water,
presence of other ions such as Chloride,
Sulphate, Phosphate and Fluoride was also
observed. As few studies are available in
literature on the effect of competing ions
moreover the concentrations of competing
ions taken in their studies were very less as
compared to natural systems.
To simulate the conditions prevailing in
natural ecosystems/ environment, the present study was undertaken to assess the
impact of these competing ions on the removal As(III) and As(V) by Activated
Alumina (AA) and Iron Oxide Impregnated
Activated Alumina` (IOIAA). were conducted. The concentrations of Chloride (0600 mg L-1), Sulphate (0-600 mg L-1),
Phosphate (0-600 mg L-1) and Fluoride (015 mg L-1) ions were studied in the range
found in ground water. Effect of these ions
on the % As(III) and As(V) removal was
investigated. The binding affinity of various competing ions such as Phosphate,
Fluoride, Chloride and Sulphate was determined using adsorption kinetics experiments.
loss studies. A known amount of regenerated
sorbent from each batch was taken and the
remaining sorbent was again subjected to
second regeneration cycle. The same procedure was repeated for second and subsequent
regeneration cycles. Regeneration studies
were carried out up to five regeneration cycles. Regeneration efficiency was tested for
repeated regeneration cycles. Exhausted
activated alumina can be effectively regenerated with 4% NaOH followed by reactivation with 0.5 M HCl. However, higher loss
of activated alumina was observed at higher
NaOH concentration due to dissolution of
activated alumina. Therefore 2% NaOH with
reactivation by 0.1 M HCl may be desirable.
88. El arsénico en las aguas subterráneas
en La Pampa Central, Argentina.
Hallazgos y consecuencias
Carlos J. Schulz1,2,3 y Eduardo Mariño2
1
Facultad de Ciencias Humanas (UNLPam).
Facultad de C. Exactas y Naturales (UNLPam)
3
Secretaría de Recursos Hídricos de la Pampa (L.P)
Uruguay 153, 6300 Santa Rosa, La Pampa. Argentina. Tel +54-2954-425166;
[email protected]
2
Investigations on the effect of competing
ions revealed that adsorption of arsenic
strongly depends on the presence of phosphate, sulfate and fluoride ions whereas
presence of chloride ion had negligible
effect on uptake of arsenic in the range
studied. The effect of competing ions on
arsenic removal followed the sequence as
PO4> F- > SO4-- > Cl-.
La presencia de Arsénico en las aguas subterráneas en la región de La Pampa central
de la República Argentina plantea una serie
de interrogantes que nos lleva a establecer
nuevas líneas de razonamiento que tiendan a
constituir otras metodologías de reflexión
hidrogeológica para la zona.
To evaluate the performance of regenerated
sorbent for arsenic removal, equilibrium
studies were carried out with the samples
after each regeneration cycle. Exhausted
AA was desorbed with different concentration of NaOH (1%, 2% and 4% by weight)
for 24 h followed by washing with water
and activation with different HCl concentration (0.1 M- 0.5M). The treatment was
carried out for 12 hours. Each batch was
dried in the oven at 378 K for 24 hours and
the final weight was measured for weight
Es importante destacar que la clásica visión
hidrogeoquímica en la caracterización de las
aguas subterráneas en lo que respecta a la
presencia del Arsénico, como de otros oligoelementos, constituye en la mayoría de los
casos un enfoque parcial o a veces equivocado de la realidad. Esta situación induce
muchas veces a toma de decisiones totalmente equivocada por los gestores del agua
o muchas veces por otras disciplinas que
tienen que ver con la saluda de las personas
(médicos, odontólogos, etc.).
74
A partir de estos conceptos y, de manera
preliminar, podemos decir que la presencia
del arsénico en las aguas subterráneas en la
región de La Pampa central de la República
Argentina constituye una incógnita desde el
punto de vista hidrogeoquímico ya que, de
acuerdo a las distintas regiones se comporta
de manera diferente, y su variación en profundidad es errática.
Como puede observarse entonces, no resulta
para nada sencillo establecer los mecanismos
que gobiernan el aporte de sales por parte de
los sedimentos que conforman la zona no
saturada (ZNS) y zona saturada (ZS) al agua
subterránea en el tiempo de contacto entre
ésta y el material que la contiene. Lo que es
indudable es que en este fenómeno deben
contemplarse una serie de factores y
parámetros tales como la alterabilidad de los
materiales ante el disolvente universal, las
condiciones climáticas, la geoquímica de las
aguas de recarga, los tiempos de contacto, la
sinuosidad del camino recorrido, los
procesos biológicos que se han llevado a
cabo en su transcurso, los parámetros
hidrogeológicos
tales
como
la
Transmisividad, Permeabilidad, Coeficiente
de Almacenamiento, etc.
Ejemplos de la anarquía de patrones
hidrogeológicos e hidroquímicos que presenta el Arsénico en nuestro medio, tanto en
lo que respecta a su distribución areal como
vertical, se verifican en casos en que en un
mismo sector se pueden localizar valores de
0,05 mg L-1 en la parte superior del acuífero y
0,30 mg L-1 en profundidad o exactamente el
fenómeno a la inversa. Asimismo, también es
importante determinar en que estado de
valencia se encuentra, si como arsénico
tetravalente o pentavalente, ya que de ello
depende en gran parte su nocividad o
toxicidad que afecta a la salud humana.
Si bien, la presencia del agua subterránea y
las posibilidades de su aprovechamiento se
encuentran condicionadas principalmente
por tres factores naturales: a) Clima, b)
Geología (litología y tectónica) y c) Geo-
morfología, la compleja génesis y presencia
del Arsénico en dichas aguas, constituye una
incógnita desde el punto de vista hidrogeoquímico y puede deberse, según a algunos
estudios realizados, a tres factores preponderantes como lo son: los litológicos, hidráulicos
y químicos.
Lamentablemente, existe un profundo desconocimiento de esta problemática por parte de
la población en general, incluyendo a los organismos vinculados a la salud que no registran
estadísticas de patologías vinculadas al tema
ni han encarado esta cuestión en el sentido de
fomentar y desarrollar investigaciones científicas que tiendan a morigerar y determinar fehacientemente el origen y comportamiento de
este elemento en las aguas subterráneas.
89. Adsorption-desorption kinetics of
As(V) in soils: Multireaction modeling
H. M. Selim and Hua Zhang
Department of Agronomy & Environmental
Management, Louisiana State University, Baton Rouge, Louisiana 70803, USA;
[email protected]
Knowledge of adsorption and desorption of
arsenic (As) on soil mineral surfaces is a prerequisite for predicting its fate in the soil environment. Kinetic data have the advantage of
taking into account possible time-dependent
reactions for adsorption, release, or desorption. Nonequilibrium conditions may be due
to heterogeneity of sorption sites and slow
diffusion to sites within the soil matrix, i.e.
slowly accessible sites with variable degrees
of affinities to heavy metals. The focus of this
investigation was (i) to quantify the kinetics
of adsorption and desorption of As in two
different soils: Sharkey clay and Olivier silt
loam; and (ii) to present multi-reaction kinetic
type models of the nonlinear type and assess
their capability of describing the sorption as
well as release or desorption behavior of As
in soils.
75
Recent approaches based on soil
heterogeneity and kinetics of adsorptiondesorption have been proposed for the
purpose of describing the time-dependent
sorption of heavy metals in the soil
environment. The multireaction (MRM)
kinetic approach presented here considers
several interactions of heavy metals with
soil matrix surfaces. Specifically, the model
assumes that a fraction of the total sorption
sites is kinetic whereas the remaining
fractions interact rapidly with solute in the
soil solution. The model accounts for
reversible as well as irreversible sorption of
the concurrent and consecutive type.
Batch kinetic experiments were carried to
determine adsorption and desorption isotherms for As (V) by our three surface soils
having different properties; Sharkey clay
and Olivier silt loam, and Windsor sand.
The technique used here is kinetic batch
type. Six initial As(V) concentrations (5,
10, 20, 40, 80, and 100 mg L-1) of
KH2AsO4 prepared in 0.01M KNO3 background solution were used. The reaction
times of adsorption ranged from 2 to 504 h.
Desorption commenced immediately after
the last adsorption time step (504 h) using
successive dilutions for 12 days. The
amount of As(V) retained by the soil following the last desorption step was determined using sequential extraction methods.
Our Results indicated that adsorption of
As(V) were highly nonlinear with a
Freundlich reaction order N much less than
1 for all soils. Adsorption of arsenate was
strongly kinetic, where the rate of As(V)
retention was rapid initially and was followed by gradual or somewhat slow retention behaviour with increasing reaction
time. Freundlich distribution coefficients
and Langmuir adsorption maxima exhibited
continued increase with reaction time for
all soils. Desorption of As(V) from all soils
were hysteretic in nature which are indications of lack of equilibrium retention and/or
irreversible or slowly reversible processes.
A sequential extraction procedure provided
evidence that a significant amount of As(V)
was irreversibly adsorbed on all soils. Moreover, the multi-reaction model with equilibrium and kinetic sorption successfully described the adsorption kinetics of As(V) to
Olivier loam and Windsor sand. This model
with optimized parameters was found to be
capable of predicting the desorption of
As(V) from these two soils. However, for
Sharkey clay, with high adsorption affinity,
an additional irreversible reaction phase was
required to predict the desorption processes.
90. Community arsenic removal system
using ADI media G2
Kiron Senapati
ANANT Technologies Inc., Tampa, Florida,
USA; [email protected]
Several treatment technologies to remove
arsenic are available for use, of which “Adsorption” has been found to be the most cost
effective and easy to implement. ADI International, Inc., of Canada www.adi.ca / Water/water.html has developed an arsenic removal media called “MEDIA G2” that performs with significant advantages over other
adsorbent media, and has been determined to
be one of the most cost effective technologies from field studies. MEDIA G2 is a
highly porous media with an extremely large
surface area to volume ratio. The technology
proposed allows for the concurrent treatment
of multiple contaminants, rendering it more
efficient and cost-effective compared to conventional treatment methods.
The combined benefits of these attributes
will be reflected in lower life-cycle treatment
costs combined with removal of other elements of concern that are not targeted for
treatment. As such, this technology presents
a tremendous opportunity to apply proven
technology in Latin America. The objective
is to offer affordable arsenic water treatment
systems to provide arsenic safe drinking
water in remote areas. The need is especially
urgent for rural communities, which consti-
76
tute 97% of the people affected by arsenic
contamination.
For a technology to be effective in arsenic
removal, it must be simple, economical,
easy to apply, requiring minimal operation
and maintenance. The MEDIA G2 selectively removes arsenic and is unaffected by
common interfering such as fluorides, chlorides, sulfates, and iron which are usually
found in drinking water. Arsenic removal
by adsorption is a simple process, which
usually does not require addition of any
chemicals during the treatment. Arsenic is
removed from water via a combination of
adsorption, occlusion (adhesion) or
solid-solution formation by reaction with
ferric oxide ions. The MEDIA G2 technology is a novel iron oxide-based media with
high surface area and enhanced selectivity
for arsenic compared to conventional adsorbents. It is ideal for groundwater treatment given its physical and chemical properties such as stability, porosity, and high
surface area.
The paper proposes to present the results of
the study undertaken in India and Bangladesh and describe the ADI Media G2 arsenic removal technology and process as
applied to small community treatment systems. The paper will also provide capital
and operating costs for implementing such
treatment systems.
91. Arsenic in groundwater and sediments from La Pampa, Argentina
P L Smedley, H B Nicolli and D G Kinniburgh
1
British Geological Survey, Wallingford, Oxfordshire, OX10 8BB, United Kingdom;
[email protected]
2
Instituto de Geoquı´mica, Av. Mitre 3100,
1663 San Miguel, Provincia de Buenos Aires,
Argentina
Groundwater from the Quaternary loess
aquifer of northern La Pampa has spatially
variable but often high concentrations of
As. Pumped groundwater samples from
boreholes and wells in the region have an
observed range of <4–5300 µg L–1. The dissolved As correlates positively with several
other trace elements which also reach unusually high concentrations: V concentrations
reach up to 5.4 mg L–1, F up to 29 mg L–1, B
up to 14 mg L–1, Mo up to 990 µg L–1 and U
up to 250 µg L–1. The groundwater is universally oxic with a neutral to alkaline pH (7.0–
8.7) and the dissolved As is present predominantly as As(V). Some of the highest
As and associated trace-element concentrations are found in topographic depressions
which are likely to be zones of groundwater
discharge and increased residence time.
Extracted porewater from a cored borehole
in one investigated topographic depression
(Tamagnoni borehole) had concentrations of
As up to 7500 µg L–1. The mineral sources
of the As in the groundwater are difficult to
identify unequivocally. The aquifer sediments have unexceptional concentrations of
As (3–18 mg kg–1), although porewater As
concentrations correlate broadly with host
sediment As concentrations. Data for selective sediment extracts suggest that secondary
iron and manganese oxides are likely to be
among the most significant minerals involved in the cycling of As.
As the groundwater is oxic, As release from
the metal oxides is concluded to be through
desorption rather than dissolution reactions.
Oxalate-extract data have been used to estimate the amount of labile As in the sediments. From an observed linear correlation
between oxalate-extractable As and dissolved As in the cored Tamagnoni borehole,
a partition coefficient, Kd, was estimated as
0.94 L kg–1. This unusually low value demonstrates the low affinity of the Pampean
sediments for As sorption. Modelling of As
sorption to hydrous ferric oxide (HFO) suggests that competition from other anions can
have a significant effect on the amounts of
sorbed As, with the biggest effect being from
vanadate at the concentrations of solutes
observed. Although HFO is probably not the
dominant Fe(III) oxide present in the Pam-
77
pean aquifer, it serves as a useful indicator
of the likely reactions involved in As release to groundwater in the region.
92. Using GIS to define As-anomalous
catchment basins considering drainage
sinuosity
Ardemirio Silva
State University Of Feira De Santana, Salvador,
Bahia, 41940-250, Brazil;
[email protected], [email protected]
Arsenic values in stream sediments of
anomalous catchment basins are a function
of several geological factors, including
average composition of underlying rocks,
geochemical controls, such as dispersion
processes and scavenging of metal ions by
oxides. The influence of all these factors, in
turn, is a reflection of sorting of minerals in
drainages during sediments accumulation.
Drainages with lower gradients and more
sinuous paths, are more likely to yield
higher As levels, as these factors restrict
dispersion. In the study area, 121 As bearing basins (above the detection limit of 4
ppb in the <177 µm sieve fraction), out of
385 sampled basins situated entirely in a
Archaean volcanic-sedimentary sequences,
the Itapicuru Greenstone belt (Bahia State,
northeastern Brazil), were modelled in a
Geographic Information System (GIS) with
respect to total lenghts of drainage and
distances from uppermost to lowermost
points. Firstly, it was calculated the presence or absence of ouliers, secondly, it was
calculated statistical parameters such as,
mean, standard deviation, median and
mode. To define the behaviour of the data a
Kolmogorov-Smirnov test was carried out.
The sinuosity indexes were calculated by
dividing total stream lenght by the distance
between uppermost and lowermost points.
The results were reclassified into three
ranges for sinuosity (low, medium and
high). To each of those range empirical values of 1, 1.5 and 2 were assigned. As values
for each basin were weighted by classes of
sinuosity and reclassified, resulting in a modified As anomaly map. The basins were automatically extracted from a Digital Elevation
Model (DEM). Some basins otherwise not
considered first priority were thus emphasized, while others which were originally
considered anomalous were de-emphasized.
Thus, the resulting As anomalous map reflects more accurately the factors afecting the
dispersion of As and filter out the cofounding
effects of physical dispersion and accumulation of As in stream sediments sampled as
part of a exploration program. Basins selected
using sinuosity-weighted As anomalies correlate well with those selected by pathfinder
associations, and the two approaches are considered complementary.
93. Determination of arsenic in river
sediments from geographical basins in the
state of Minas Gerais, Brazil, using GFatomic absorption spectrometry
Julio C. J. Silva (PQ), Sandro H. D. Freitas (IC),
Olivia V. M. S. Vasconcelos1 (PQ), Virginia S.
T. Ciminelli1 (PQ)
Institutos do Milênio: Água-uma visão mineral,
CNPq, CAPES; Department of Metallurgical
Engineering and Materials, UFMG, Brazil;
[email protected]
Environmental pollution is a problem of
fundamental importance in relation to
aquatic life and its quality. This problem is
especially critical in the Ferrous Quadrilateral in the state of Minas Gerais, one of the
most important mining areas in Brazil, which
has suffered the effects of predatory mining
activities since the XVII century. Among the
many chemical pollutants, arsenic is considered to be one of the most concerning, its
high toxicity places at risk both the environment and human health. Work has then been
carried out to develop a method for the determination of arsenic in samples of river
sediments by means of graphite furnace
atomic absorption spectrometry (GFAAS).
The samples of interest were collected from
78
five geographical basins in the State of
Minas Gerais, Brazil. The samples (approximately 100 mg) were digested in a
microwave oven with cavity and closed
vessels using an acid mixture (HNO3 + HF
+ H3BO3). In the experiments graphite pyrolytically covered tubes were used, and
integration of signals and chemical modifiers (0.015 mg Pd + 0.01 mg Mg(NO3)2).
The total volume (sample + diluent + modifier) delivery in the graphite tube was 50
µL, the pyrolysis temperatures and atomization was 1400 and 2500°C, respectively.
The accuracy of the procedure was evaluated with certified reference material (NIST
2780 - Hard Rock Mines Waste and NIST
2780 - Inorganics in Marine Sediment) and
recovery and addition tests. The quantification was conducted using the analyte addition method. Preliminary results for arsenic
(λ = 196 nm) showed recoveries around
100% for the certified samples. To compare
the obtained values and the certified values
two statistical tests were used, the F test
and T test matched, and the values obtained
were not significantly different within the
evaluated interval (P = 0.05). The arsenic
concentration obtained in one of the sediment samples (SF 017) was 11.4 mg L-1.
Additional studies are being conducted and
will be extended to the samples of interest.
94. Causas sociales de la patalogía del
hidroarsenicismo en las localidades de
Urutau y Benado Solo departamento
Copo – Provincia de Santiago del Estero,
Argentina
Gladys N. Soria de Paredes
Programa de Prevención y Control de
Hidroarsenicismo (H.A.C.R.E.) – Ministerio de
Salud y Desarrollo Social de la Provincia
Santiago del Estero, Argentina, 4200 Santiago
del Estero, Argentina;
[email protected]
El presente trabajo de Investigación apunta a
poner de manifiesto que la escasa dispon-
ibilidad de Agua y las Causas Sociales emergentes del Medio Ambiente donde habitan los
pobladores de Urutaú y Benado Solo, sigue
siendo una de las grandes preocupaciones de
los pobladores del Departamento Copo en la
Provincia de Santiago del Estero – Argentina
– desconociendo los mismos la importancia
de la calidad para sus vidas.
De acuerdo a las visitas realizadas en la zona
se ha podido comprobar la falta del elemento
vital para consumo humano, ganado y cultivos condicionando los medios de sustento
para esta población rural, poniendo énfasis en
contaminación arsenical.
En estas zonas el hombre normalmente consumió el agua de represas, pozos perforados
extraídos con baldes, molinos de viento, y
bombas cuando cuenta con los elementos
necesarios o bien ha construido aljibes, calicantos de diversos tamaños donde almacena
agua de lluvias para consumo.
En estas diferentes formas de almacenamiento muchas veces no cuentan las condiciones sanitarias mínimas necesarias para ser
usadas en el consumo humano, pero a pesar
de esto u ante la necesidad los pobladores
continúan consumiendo este tipo de agua,
preparando sus alimentos y también usándola en la higiene personal.
Esta agua así obtenida satisface sus necesidades, una de las fuentes más utilizadas en la
actualidad es el agua subterránea o sea de la
napa freática con alta concertación de arsénico. Ante esta realidad surgió un
interrogante ¿desde que época los
pobladores de la zona ponen en riesgo su
vida al consumir agua contaminada?.
Indagadas estas instancias, las respuestas
obtenidas son paralizantes a tal punto que
paso a ser un problema social, político y
sanitario en la provincia.
En la actualidad se han detectado casos en la
población con afecciones contraídas en el
medio ambiente donde habitan, enfermedad
crónica y agudas, de fácil diagnostico, observables ha simple vista se pueden observar
79
las manifestaciones dermatológicas propio
de la ingesta de agua arsenicales.
Este trabajo de investigación pretende entre
sus objetivos ser un aporte desde la Investigación Social en la relación hombre-medio
y de que manera influye en estas poblaciones rurales el marco histórico,
geográfico y cultural, como así también el
nivel socio económico y de que manera son
validas las alternativas de solución para
logra erradicar definitivamente este flagelo
que viene condicionando sus vidas desde
muchas décadas.
95. Lymphocyte subpopulations and
cytokine secretion in an infant population exposed to arsenic
Soto-Peña GA, Luna AL, Acosta-Saavedra L,
Conde P, López-Carrillo L2, Cebrián ME,
Bastida M3, Calderón-Aranda ES, Vega L*.
*Sección Externa de Toxicología, Centro de
Investigación y de Estudios Avanzados del IPN.
Av. IPN 2508, San Pedro Zacatenco, Mexico D.
F. 07360, Mexico; [email protected]
2
Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico.
3
Jurisdicción Sanitaria 5, Secretaría de Salubridad y Asistencia, Zimapán, Hidalgo, Mexico
In animal models and human cells in vitro,
arsenic has shown to modulate some transcription factors, cytokine secretion, cell
proliferation, and hypersensitivity response,
among other cellular and systemic activities
that confers arsenic it’s immunotoxic ability.
To date, no studies have been conducted
with the aim of immunotoxic effects on
human, neither on infant populations (that
could be more susceptible to arsenic effects).
We evaluated some parameters within the
immunological status in an infant population
in Mexico exposed to arsenic via drinking
water.
Peripheral blood mononuclear cells
(PBMC) of 66 infants (6 to 10 years old)
from an arsenic exposed area were collected. Proportion of lymphocyte subpopu-
lations, their mitogenic proliferative response, and activation capacity were evaluated and related with the arsenic levels found
in urine. In this study we included children
with no clinical history of cancer development or immune related diseases, children
participating in this study were not taken any
drugs for at least three weeks before sampling and a questionnaire including exposure
history, exposure to heavy metals and pesticides, socioeconomic status and clinical
history was answered by their legal guardians.
Urine samples were collected and kept frozen until arsenic concentration was evaluated by hydride generation atomic absorption spectrophotometry (iAs, MMA and
DMA). Heparinized blood samples were
collected and mononuclear cells subpopulations were evaluated in whole blood samples, mitogenic response and cytokine secretion were evaluated on isolated cultured cells
after 24 or 48 h of culture. Also hemoglobin
and lead levels were evaluated.
In this infant population we observed a reduction in the proportion of helper T cells (CD4)
subpopulation (β = -0.0039, p = 0.097), and
in the CD4/CD8 ratio (β = -0.0032, p =
0.090) that was related with arsenic levels in
urine. The proportion of cytotoxic T cells
(CD8), B cells and Natural killer cells was not
modified by arsenic exposure. In isolated
lymphocytes we observed a reduction in the
proliferative response to PHA-stimulation (β
= -0.0016, p = 0.010), and in the IL-2 secretion (β = -0.018, p = 0.001) related with an
increased in urine arsenic levels. Meanwhile
IL-4, IL-10, or IFN-γ secretion was not modified by arsenic exposure. Additionally, we
observed an increment in GM-CSF secretion
on LPS/IFN-γ activated mononucleated cells
associated with increasing arsenic levels in
urine (β = -0.0099, p = 0.000). Gender, age,
socioeconomic status, or other co-variables
evaluated in this study did not modified the
relationship of the immune response parame-
80
ters evaluated with the arsenic levels found
in urine of exposed individuals.
These data indicate that arsenic exposure
could alter the activation processes of T
cells and macrophages, representing an
immunodeppressed status that could favor
opportunistic infections and cancer development in human populations exposed to
arsenic. In addition, several reports of in
vivo genotoxic effects of arsenic exposure
in Mexican human populations had indicated a gender differential effect of arsenic
exposure. Some in vitro studies of arsenic
effects on immune response parameters had
also indicated that this susceptibility is
related with helper T cells in adult women.
96. Mineralogical study of arsenicenriched aquifer sediments at Santiago
del Estero, northwest Argentina
O. Sracek1*, M. Novák1, P. Sulovský1, R. Martin2, J. Bundschuh2, P. Bhattacharya3
1
Institute of Geological Sciences, Faculty of
Science, Masaryk University, Kotlářská 2, 611
37 Brno, Czech Republic; [email protected]
2
Facultad de Ciencias Exactas y Tecnologias,
Universidad Nacional de Santiago del Estero
(UNSE), Av. Belgrano 1912, 4200 Santiago del
Estero, Argentina
3
Resources Engineering, Kungliga Tekniska
Högskolan, SE-100 44 Stockholm, Sweden
Shallow aquifer located in an alluvial fan at
Santiago del Estero, northwest Argentina,
is enriched in arsenic. Sediments from sites
with high As concentration were collected
by hand auger and studied by X-ray diffraction and by electron microprobe. X-ray
diffraction confirmed the presence of
quartz and albite. Concentrations of total
organic carbon (TOC) in soil are low, but
concentration of total inorganic carbon
(TIC) may be significant.
The electron microprobe investigation
found abundant glass particles with fluidal
structure. The grains show significant
weathering (voids, dissolution pits etc.).
Biotite grains present in sediments are also
weathered. Iron oxyhydroxides occur in
isolated spots on the surface of silicate minerals, but not as continuous coatings. Heavy
minerals were represented by altered ilmenite, monazite, zircon, and garnet with predominant almandine component.
The primary source of arsenic could not be
determined unequivocally, but volcanic glass,
and biotite are potential candidates. Ferric
oxyhydroxides, which are important adsorbents of arsenic, seem to have formed by precipitation of iron released from titanomagnetite, ilmenite, and biotite. However, the
amount of precipitated ferric oxides and hydroxides is limited and, furthermore, their
arsenic adsorption capacity depends on factors like pH and ionic strength of ground water and on concentrations of species competing for adsorption sites.
97. Sorption and desorption behavior of
arsenic in a soil
S. Tokunaga* and M.G. M. Alam
National Institute of Advanced Industrial Science
& Technology; Central 5, Higashi, Tsukuba,
Ibaraki 305-8565 Japan; [email protected]
Arsenic carries a +III or +V valence in soil
environments. Difference in the behavior of
As(III) and As(V) in soils has not been well
known. The authors studied sorption and
desorption behavior of As(III) and As(V) in
Kuroboku soil, one of the typical soils in
Japan. Comparison was made between the
behavior of As(III) and As(V).
A 0.25 g of soil was contacted with 25 mL
of 1.60 mg L-1 As(III) or 14.9 mg L-1 As(V)
solution for 16 h under N2 atmosphere. The
As(III) sorption was less pH-dependent, only
75% of As(III) ion being removed in the pH
range 8 to 10. On the other hand, the As(V)
sorption was highly pH-dependent, almost
100% of As(V) ion being removed in the pH
81
range 2 to 5 in spite of much higher initial
As concentration. Little As(V) was sorbed
in the pH range > 11. The sorption rates of
As(III) and As(V) ion were measured at pH
8 and 4, respectively, under N2 atmosphere.
The kinetic data were analyzed using zeroorder, first-order, second-order, third-order,
parabolic diffusion, two-constants rate,
Elovich-type, and differential rate models.
The soil was artificially contaminated with
As(III) or As(V) ion. The contents of
As(III) and As(V) were 1,622 and 3,190
mg kg-1, respectively. The desorption rates
of As(III) and As(V) ion were measured by
controlling pH at 4, 7, and 9 under N2 atmosphere. The desorption of As(III)
reached equilibrium within 3 h. The desorption rate of As(III) increased in the
order at pH 9 < pH 7 < pH 4. A significant
amount of As(V) ion was detected in the
leachate at pH 9, indicating oxidation of
As(III) ion. Only several µg/L of As(V)
desorbed from As(V)-contaminated soil at
pH 4. The desorption rate of As(V) increased in the order at pH 4 < pH 7 < pH 9.
The desorption of As(V) was still much
less than that of As(III) at pH 7. At pH 9,
the desorption of As(V) continuously increased even after 10 h.
98. Estudios de especiacion de arsenico
en agua por fluorescencia de rayos X y
voltametría de redisolución catódica
L. Valcárcel, J. Estévez, A. Montero, I. Pupo
CEADEN: Centro de Aplicaciones
Tecnológicas y Desarrollo Nuclear Calle 30 No
502, Playa, Ciudad de la Habana, Cuba;
[email protected]
Se implementaron dos métodos para la
determinación de las especies inorgánicas
de arsénico en agua por Fluorescencia de
Rayos X (FRXDE) y Voltametría de Redisolución Catódica (VRC).
Durante el desarrollo del primer procedimiento se estudiaron los rendimientos de la
precipitación de As (III) y As (V) con
APDC, que posteriormente se determinaron
por un método absoluto de capa fina de
FRXDE. Se aplicaron además procesos de
oxidación reducción para la determinación
del contenido total del elemento.
Paralelamente se implementó un método
polarográfico alternativo de análisis de las
especies de arsénico, utilizando la variante
de VRC. El As (III) se reduce a As (0) y se
deposita en la gota de Hg en forma de un
compuesto intermetálico de As-Cu-Hg. La
señal medida corresponde a la reducción de
As (0) a As (-3). La determinación del contenido total de arsénico inorgánico requirió
de un paso previo de reducción de As (V) a
As (III).
En el trabajo se reflejan los parámetros
metrológicos de los métodos tales como
Precisión, Límites de Detección e Incertidumbre. La exactitud se evalúa por comparación de los resultados obtenidos por
ambos procedimientos.
Estos métodos fueron aplicados en el análisis
de las especies inorgánicas de este elemento
en aguas naturales.
99. Transforming growth factor alpha
concentration in exfoliated bladder
epithelial cells from Mexican population
environmentally exposed to inorganic
arsenic
Olga L. Valenzuela1, Gonzalo Garcia-Vargas2, Araceli
Hernandez-Zavala1, Eliud A. García Montalvo1, Dori
R. Germolec3 and Luz M. Del Razo1
1
Toxicology, Cinvestav-IPN, Mexico City
2
Medicin, UJED, GP, Durango, México
3
Environmental Immunology Laboratory,
NIEHS, NIH, RTP, NC, USA
Arsenic is a well established human carcinogen and is associated with a variety of cancers including those of skin, liver, kidney,
lung and bladder. The activation of the proliferation cellular-induced growth factor has
been linked to the biological effects of arse-
82
nic. Recently has been demonstrating that
overexpression of growth factors, such as
transforming growth factor alpha (TGF-α),
promote the formation of skin tumors.
TGF-α is secreted by epithelial cells in a
variety of normal tissues (including skin,
pituitary and brain) and function as a
paracrine mediator of epithelial cell proliferation. The urinary concentration of TGFα has often been used as a marker of various malignancies (e.g., liver, lung, bladder,
and skin cancer) or as an indicator of an
elevated risk of cancer in humans. In addition, increased TGF-α production has previously been reported in normal human
keratinocytes treated with arsenite and in
the skin of mice exposed to arsenite in
drinking water.
This study examines the relationship between urinary profiles of arsenic and TGFα concentrations in exfoliated bladder
epithelial cells among 90 residents (18-51year-old) in both high and low inorganic
arsenic-exposed subjects of an endemic
region of central Mexico.
Previous studies carried out in the local
populations have found an increased incidence of pathologies, primarily skin lesions
that are characteristic of arseniasis. Additionally in this study, we compared the
pattern of urinary methylated metabolites
between persons with and without skin
lesions associated to arseniasis in an endemic Mexican area.
Urinary arsenic species and total arsenic
(TAs) were measured by hydride generation atomic absorption spectrometry
method. The concentration of TGF-α in
urothelial cells was measured by using an
enzyme-linked immunoabsorbent assay.
The participants on this study are from
areas exposed to different concentrations of
arsenic in drinking water (6 – 378 µg L-1).
Preliminar results in 75 individuals show a
statistically significant positive correlation
between the log-normalized TGF-α concentration in exfoliated cells and the TAs con-
centration in urine (R = 0.44, P < 0.001).
However, this association is higher between
TGFα levels and DMA in urine (R = 0.47, P
< 0.001). Besides, people exposed to high
concentration of arsenic (mean 114 µgAs/g
creatinine) was significantly (P < 0.05)
greater in TGF α levels than individuals with
lower arsenic exposure (mean 26.6 µg As g-1
creatinine). People from areas with high
arsenic concentration had a significantly
higher TGF α concentrations in urothelial
cells than people of areas with low arsenic
exposure (P<0.05). In addition, the average
TGF-α concentration was significantly
higher in exposed individuals as compared to
unexposed controls: 67.5 vs. 34.6 pg mg-1
protein (p = 0.020). Notably, exfoliated cells
isolated from exposed individuals with skin
lesions contained significantly greater
amount of TGF-α than cells from exposed
individuals without skin lesions: 84.5 vs.
39.1 pg mg-1 protein (p = 0.017). These results indicate that in arsenic-endemic areas,
the concentration of TGF-α in exfoliated
bladder epithelial cells may serve as a
marker of the exposure to inorganic arsenic
in drinking water and as an indicator of adverse epidermal health effects associated
with this exposure.
100. Arsenic mobility in the rhizosphere
of the tolerant plant Viguiera dentata
G. Vázquez-Rodríguez, M.G. MonroyFernández, R. Briones-Gallardo*
Facultad de Ingeniería-Instituto de Metalurgia,
Universidad Autónoma de San Luis Potosí. Av.
Sierra Leona 550, Col. Lomas 2ª. Sección. San
Luis Potosí, S. L. P. México; *[email protected]
The arsenic (As) mobility or retention in
soils as a result of mining activity is directly
related to the chemical equilibria between
the existing phases (soluble, mineral or biological). In polluted sites, the exposure of
plants to arsenic is determined by these equilibria at the rhizosphere. In this work, arsenic
mobilization in the rhizospheric soil (RS) of
83
a tolerant plant taxonomically identified, as
Viguiera dentate was studied. The plant
was collected in the mining district of Villa
de la Paz Matehuala- SLP, Mexico. In this
site, a total arsenic concentration in
rhizospheric soils 3867 µg g-1RS was found.
The analysis of the total arsenic concentration on dry total biomass (DB) of this plant
was 94.8 µg As g-1DB, distributed as 82%,
12% and 6% in leaves, stem and root, respectively. This distribution was further
studied as available and bioavailable arsenic fractions for physicochemical and biological mobilization, respectively.
101. Determinación del contenido de
arsénico en productos marinos entregados
por el Programa de Alimentación Escolar
(PAE), de la Junta Nacional Escolar y
Becas (JUNAEB), Vii región, Chile
The physicochemical mobilization in the
rhizospheric soil was analyzed by two different tests of successive sequential extraction (ESS). The results have shown that the
available fraction by ionic exchange was 40
µg As g-1SR while 72 µg As g-1SR were associated to carbonates phases. These last susceptible of being mobilized by acidification
of soil at a pH value of 5. Also, 687 µg As
g-1SR were adsorbed on iron and manganese
oxides. A modified ESS protocol was used
in order to favor chemical availability of
arsenic for anionic exchange with a soluble
phosphate salt. It was observed that the
available arsenic concentration, under such
conditions, corresponds to 83.4% of the
arsenic associated to iron and manganese
oxides which might suggests that arsenic is
in the form of arsenates. Finally, arsenic
bioavailability in the rhizosphere was determined using a synthetic solution that
resembled the organic acid solution found
in plants at a pH value of 4.7. The available
arsenic concentration at the interface of the
biological surface exposed in the
rhizosphere of Viguiera dentata is 147 µg
As g-1SR.
El objetivo del presente estudio fue determinar el contenido de arsénico total e inorgánico en productos marinos entregados por
el Programa de Alimentación Escolar (PAE),
de la Junta Nacional de Auxilio Escolar y
Becas (JUNAEB), VII región, Chile. La
determinación de arsénico total e inorgánico
se realizo sobre 35 muestras (24 filetes de
merluza, 5 pulpas de salmón, 5 Jurel en conserva y 1 surtido de marisco deshidratado),
obtenidas de las empresas concesionarias
que atienden el PAE de la VII región. La
determinación de Arsénico total se realizó
por digestión por vía seca. En el caso del
arsénico inorgánico, se utilizó un procedimiento de extracción por solventes, obteniendo en todos los casos resultados reproducibles y representativos.Para la determinación analítica se utilizó un Espectrofotómetro de Absorción Atómica (AAS)
Varian A 55 acoplado a generación de
hidruros.
The results of this work show that not all
arsenic in soils is available, nevertheless it
was found that the arsenic accumulation
observed in the plants studied, could be the
result of a progressive exposure of low
arsenic concentration of the plant that explains its tolerance.
S. Vilches1, G. Andrade1, O. Muñoz2, J.M. Bastías1
1
Departamento de Ingeniería en Alimentos,
Universidad del Bío-Bío, Casilla 447, Chillán,
Chile; [email protected]
2
Centro de Estudios en Ciencia y Tecnología de
Alimentos, Universidad de Santiago de Chile,
Casilla 33074, Correo 33 Santiago, Chile;
[email protected]
La concentración mínima Arsénico total
encontrados en los productos marinos fue de
0.379 µg g-1 base húmeda (bh) y la máxima
de 1.404 µg g-1 (b.h.), sobrepasando seis
muestras el límite establecido por el Reglamento Sanitario de los Alimentos de Chile
(RSA), para pescados (1 µg g-1). La concentración mínima de Arsénico inorgánico obtenido fue de 0.012 µg g-1 (bh) y la máxima
de 1.130 µg g-1 (bh), no sobrepasando ninguna muestra el límite establecido por el
RSA, ya que sólo establece arsénico inor-
84
gánico para mariscos y crustáceos (2 µg g1)
, siendo la muestra con mayor concentración la de surtido de mariscos deshidratados.
El Análisis de ANOVA por especie, producto y proceso de los contenidos de Arsénico total e inorgánico en las muestras
analizadas, arrojan que la especie influye
en forma significativa en las concentraciones obtenidas y en menor grado el tipo
de producto, pero los procesos en sí no
afectan de manera significativa tales concentraciones.
102. Natural red earth – an effective sorbent for arsenic removal
Meththika Vithanage1, Rohana Chandrajith2,
Athula Bandara3 and Rohan Weerasooriya1
1
Chemical Modeling Laboratory, Institute of
Fundamental Studies, Kandy, Sri Lanka;
[email protected]
2
Department of Geology, University of
Peradeniya, Peradeniya, Sri Lanka
3
Department of Chemistry, University of
Peradeniya, Peradeniya, Sri Lanka
Arsenic is present mainly in water as a
natural contaminant mainly in the form of
arsenate and arsenite. The natural release of
arsenic species into groundwater results in
detrimental health effects. Arsenic toxicity
leads to a host of problems including skin
cancers, Bladder and lung cancers, tumors,
keratosis and hyperpigmentation. Therefore
attention is focused to determine dominant
adsorptive minerals to characterize them
systematically for better prediction of arsenic removal from natural systems. This
study was focused on modeling the adsorption of arsenite and arsenate on to natural
red earth (here after NRE) found in Sri
Lanka.
X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) and Scanning Electron Microscopic (SEM) analysis were performed to
determine the characteristics of red earth.
Potentiometric surface titrations of NRE,
were carried out by auto-titration system
under inert environmental condition for three
different ionic strengths. The retention of As
species, both As3+ and As5+ ([As3+] = [As5+]
= 0.385 µmol/L =50 µg L-1 of As3+) were
examined as a function of pH and ionic
strength in single- (As3+ or As5+ only) and
dual-sorbate (As+3 and As+5) systems using
AAS. Fourier Transform Infra Red (FTIR)
studies were performed to study the mechanisms of surface complex formation. Experimental results were modeled using diffuse layer model.
NRE is found to be dominated with SiO2
(54.15%), Al2O3 (20.73%), Fe2O3 (12.39%)
and TiO2 (5.54%). No peaks were obtained
for Al and Fe or other constituents from
XRD indicating that Al and Fe are in the
surface coating, not in the crystal structure.
Proton titration data of red earth showed that
pHzpc = 8.8, which was fitted well with the
modeling, denoting the red earth surface is
dominantly positive when pH < pHzpc. Both
As3+ and As5+ were adsorbed over 95% on to
red earth when initial [As3+] = [As5+] = 0.385
µmol/L in single sorbate systems. In the dual
sorbate system, when both As3+ and As5+ are
present; the retention of As3+ decreases by
about 80% above pH > 7, however pH < 7
adsorption of both species were shown
strong. Modeling results showed a competition between arsenic species to the solid
binding sites. However both experimental
and modeled data showed that there is no
dependency of arsenic species on pH or
ionic strength in both single and dual sorbate
systems, which indicates that the affinity of
arsenic species on to NRE is strong forming
inner sphere complexes with the NRE surface. From the FTIR studies it was suggested
that arsenite form monodentate complexes
while arsenate form bidentate complexes
with NRE surface. As determined by the
simple diffuse layer model the binding constants were very well fitted with experimental data, proving that red earth can be effectively used to remove arsenic from aqueous
85
systems by modifying the available filtering systems.
103. Natural arsenic in groundwater: a
case study from central Italy
R. Vivona1, E. Preziosi1, G. Giuliano1, B. Madé2
1
Water Research Institute, IRSA-CNR, 1, Via
Reno – 00198, Rome, Italy
2
Ecole des Mines de Paris, CIG, 35, rue St
Honoré – 77305, Fontainebleau, France
The widespread presence of high concentrations of natural micro-pollutants is well
known in the volcanic aquifers of central
Italy where groundwater are largely exploited for agricultural and drinking purposes. Their presence is related to the alkaline-potassic volcanism which developed
along the Tyrrhenian margin of the Italian
peninsula in the Quaternary age.
The aim of this research was to characterize
the groundwater system and the geochemical processes by means of an integrated
methodology including field activity (collection of groundwater samples from wells,
springs and rivers), chemical analysis in
laboratory, geochemical modelling to study
the thermodynamic state of the waters,
minor elements origin and their enrichment
in the solution in a pilot area about 100 km2
north of Rome.
The interest was pointed out on F and As,
the latter being a cancerogenic element
which is often above the threshold value for
drinking waters (10 µg L-1 fixed by the
European Council Directive 98/83/EC) in
several Italian aquifers. The study of minor
elements allowed us to better understand
the hydrogeological setting of the area and
to define a local hydrogeological scheme;
moreover the analysis of the hydrofacies
and the elements contents was useful to
shed light on the origin and the processes
leading to high concentrations of minor
elements, their evolution along the
groundwater pathway and possible mecha-
nisms of their natural removal from solution,
giving at the same time new insights on the
quality of groundwater of the study area.
The integration of a quantitative study (discharge measurements along the main
streams, piezometric levels in the wells,
elaboration of the water table map) with a
qualitative analysis (characterization of the
hydrofacies and study of the spatial distribution of elements concentration) was a helpful
tool to point out the differences in the waterrock interaction along groundwater flow and
to understand the concentration variations
(in particular of As, F and Ca) observed
from the highest sector of the region downstream along the main flow direction. Two
hypothesis were made about the possible
geochemical processes responsible of the
hydrochemistry observed in the sampled
waters: the good correlation between As an
F and their decrease with Ca augmentation
downstream was related in the first hypothesis to the precipitation of As-F-bearing minerals (fluorapatite); in the second hypothesis
a dilution due to mixing processes between
waters of different origin and different composition (volcanic aquifer + sedimentary
aquifer) was considered.
104. Infield detection of arsenic using a
portable digital voltameter
Magdalena Wajrak
School of Natural Sciences, Edith Cowan University Joondalup Campus, JOONDALUP, WA,
6027; [email protected]
There are a growing number of countries in
the world where arsenic in groundwater has
been detected at concentrations greater than
the WHO Guideline Value of 10 µg L-1. These
include; Argentina, Bangladesh, Chile,
China, Hungary, India, Mexico, Peru, Thailand, and the USA. More recently this issue
has also become a concern in Western Australia. A decline in the watertable due to a
low period of rainfall and the disturbance of
sulfidic peat soils by dewatering and exca-
86
vation in some of Perth’s suburbs has resulted in widespread acidification of
groundwater and has caused the water to be
contaminated by arsenic and other metals.
Groundwater forms 70% of Perth’s water
usage and people use the groundwater to
water their vegetable gardens and thus expose themselves to high levels (up to 800
µg L-1) of arsenic.
Of particular concern is the situation in
Bangladesh where it is estimated that there
are more than 1 million people drinking
arsenic-rich water (>50 µg L-1). The consequences of arsenic poisoning have already affected many thousands; skin discoloration, ulcers and cancer of the skin,
lungs and intestines. It is imperative that
people stop drinking from wells where
arsenic levels are high. However, as yet,
there is no reliable, simple, inexpensive
and field-based method for arsenic detection.
The current methods of arsenic detection
use sophisticated and expensive laboratory
based instruments, such as Atomic Absorption Spectroscopy - hydride generation
(AAS-HG) and Inductively Coupled
Plasma – Mass Spectrometry (ICP-MS)4.
With over 6 million wells spread across
Bangladesh, using such methods is not only
highly expensive, but also time-consuming.
What is needed is a method which can be
used in-field, is relatively easy to implement, accurate and has a detection limit of
10 µg L-1.
This research involves the development of
an infield method for arsenic detection in
ground-water using anodic stripping voltammetry (ASV). The instrument used is a
Portable Digital Voltammeter, PDV6000,
designed by Monitoring Technologies International (MTI) company in Perth, WA.
Using solid gold working electrode the
instrument can detect down to 5 µg L1
using arsenic standard solution in ethanoic
acid electrolyte with a 5 minute deposition
time. The results are reproducible and lin-
ear and speciation between the two stable
forms of arsenic, As 3+ and As 5+ is possible.
The method is now being validated using
‘real’ ground water samples from Perth suburbs by comparing the ASV results to ICPMS. Initial results are promising, the voltammeter values are within +/- 3 µg L-1of the
ICP-MS method. The next step in this project is to implement and validate this method
for groundwater samples from Bangladesh
(currently awaiting the arrival of those samples).
105. Occurrence of hexafluoroarsenate in
fluoride-rich waters – blessing or curse?
Dirk Wallschläger
Environmental & Resource Sciences Program,
Trent University, 1600 West Bank Dr, Peterborough, ON K9J 7B8, Canada;
[email protected]
The hexafluoroarsenate anion [AsF6]- is an
extremely stable compound well known in
inorganic chemistry, but to date, it has received little to no attention in environmental
As speciation studies, despite the fact that it
is used as a pesticide and in certain types of
batteries. Synthetic literature also suggests
that [AsF6]- may be formed from arsenate
and dissolved fluoride or fluoride minerals.
The lack of studies on the occurrence of
[AsF6]- in natural waters is mostly due to the
lack of analytical methods for its determination. In this paper, I present a method for the
selective and sensitive determination of
[AsF6]- in waters by anion-exchange chromatography coupled to inductively-coupled
plasma mass spectrometry (AEC-ICP-MS),
and demonstrate that this compound occurs
in certain types of waters.
Separation of [AsF6]- from all other known
inorganic As species and methyl-As pesticides was accomplished by AEC using perchlorate as the eluant under alkaline conditions. Detection limits around 5 ng L-1 As
were achieved. The species mass balance (=
87
sum of all detected species vs. the independently determined total As concentration) in real world samples was excellent
(95-110%). I will discuss why other common As speciation methods are unsuitable
for waters where [AsF6]- occurs, which may
explain why it hasn’t been detected in the
environment before.
Hexafluoroarsenate was detected in process
waters from an industrial fluorination process, where it constituted the vast majority
(78-100%) of the total As concentration. It
was not at all removed by iron hydroxide
co-precipitation.
Iron-sulfur (Fe-S) minerals have been recognized to play important parts in the overall
fate of As in the reducing aquifers. Understanding the interaction of As with Fe-S
minerals is more important when deeper
wells are sought as an alternative to the exisiting shallow contaminated wells.
In this study, we have investigated As
exchange at the interface between water and
Fe-S minerals under controlled laboratory
conditions. From our experiments, we expect
to outline the geochemical reactions
affecting the mobilty of the As in these
environments.
I will present further experiments on the
formation and fate of [AsF6]-, and illustrate
under what circumstances this species
might be encountered in natural waters,
with particular reference to ground waters
that contain both elevated As and fluoride
concentrations. I will also attempt to discuss if the occurrence of [AsF6]- is positive
or negative with respect to As toxicity and
environmental cycling and fate, and what
implications this may have for potential
treatment strategies.
Batch experiments equilibrating synthetic
Fe-S minerals (FeS2 and FeS) with As (arsenite or arsenate) were performed in oxic,
anoxic and sulfidic environment. In the first
set of experiments, As oxyanions were
equilibrated with Fe-S minerals, while with
the second set, As was spiked to the dissolving Fe-S minerals solution after they had
partially dissolved for 1, 3 and 5 days. Samples were collected daily for 5 days after
spiking. Experimental environments were
controlled by standard methods. Total As, Fe
and S in the collected samples were analyzed
by ICP-MS.
106. Interaction between arsenic
oxyanions and iron-sulfide minerals
As
reported
previously,
pronounced
differences between the solubilities of
different Fe-S minerals were observed. As
for the corresponding Fe-O minerals,
arsenate generally showed a higher affinity
for the studied Fe-S mineral surfaces than
arsenite, which often remained in solution to
a significant extent. Also, FeS adsorbed both
As species stronger than FeS2. The kinetics
of these reactions will be described, and
apparent equilibrium distribution coefficients are determined.
1
Prabhas Kr. Yadav, Dirk Wallschläger
Environmental & Resource Studies Program,
Trent University, 1600 West Bank Dr, Peterborough, ON K9J 7B8, Canada;
[email protected]
Arsenic (As) contaminations of groundwater used for drinking water production is
among the most severe environmental
problems encountered in several parts of
world. Studies have shown that As usually
originates from geogenic sources, and is
mobilized through geochemical changes
caused directly or indirectly by human activities. However, factors of As release and
mobilization in the groundwater are still
under investigation.
Our results suggest that removal of As from
the solution is severely by the constituents of
the dissolving minerals (see figure below),
likely due to the modification of the surface
during the partial dissolution process and/or
reactions between the released Fe and S
species with the added As species. We also
88
observed reddish-brown Fe-O precipitate
on the Fe-S mineral surface after 2 days
under oxic and anoxic conditions. We
believe this new precipitate to be some FeO minerals.
Finally, we will combine the results
obtained from batch experiment withs flow
through experiments and derive result as a
simple model which describes the changes
in As speciation and mobility as it crosses
from one set of geochemical conditions into
another in order to simulate the effects of
geochemical transition zones.
107. Arsenic exposure in rural
population from Atacama Desert, Chile:
Characterization of arsenic species in
water, urine, hair and nails
J. Yáñez, H. Mansilla & V. Fierro1, L. Cornejo
& L. Figueroa2, and R.M. Barnes3
1
Faculty of Chemical Sciences, University of
Concepción, Concepción, Chile;
[email protected]
Department of Chemistry, Faculty of Sciences,
University of Tarapacá, Arica, Chile
2
Centro de Investigaciones del Hombre en el
Desierto (CIHDE)
3
University Research Institute for Analytical
Chemistry, URIAC, Amherst, MA, USA
Por primera vez se presenta a la comunidad
científica un estudio integral de caracterización de arsénico en aguas de consumo
humano, su transformación en otras
especies químicas y su eliminación en
orina, cabello y uñas en una población
altamente expuesta del norte de Chile
(Illapata). Se determinó que el As(V) fue la
especie más abundante en las aguas del río
Camarones y vertientes asociadas, constituyendo la principal especie ingerida por la
población. El río Camarones presentó
concentraciones de hasta 1252 µg L-1 de
arsénico total, siendo casi exclusivamente
As(V). En la orina de la población
expuesta, la distribución de las especies
As(III), As(V), MMA y DMA fue de 5, 1, 6
y 87% respectivamente. Estos resultados
indican que existe una alta capacidad de
metilación de arsénico de los individuos de
Illapata, en comparación con la población
control y con datos de la literatura. El As(V)
ingerido también fue transformado y
depositado en cabello principalmente a la
forma de As(III), que fue la especie más
abundante encontrada, 57 y 85% en individuos de la población control y expuesta
(Esquiña e Illapata respectivamente). Se
relacionó la concentración de arsénico total
en cabello y uñas con la edad de los
individuos expuestos crónicamente, encontrándose una mejor correlación con cabello
(0.64) en comparación con las uñas (0.44).
89
Topic areas with abstract number
Remediation material and technology:
1 – 4 – 5 – 11 – 14 – 17 – 18 – 20 – 23 – 26
– 27 – 31 – 39 – 40 – 44 – 45 – 53 – 65 –
70 – 71 – 83 – 86 – 87 – 90 – 102
Arsenic (biogeo)chemistry and analysis:
10 – 16 – 22 – 24 – 32 – 39 – 45 – 50 – 87
– 89 – 93 – 97 – 98 – 100 – 104 – 105 –
106
Environmental management:
2 – 12 – 19 – 21 – 37 – 51 – 52 – 54 – 60 –
64 – 66 – 67 – 71 – 81 – 92 – 94 – 101 –
107
Geoenvironmental situation and processes:
3 – 7 – 8 – 9 – 21 – 24 – 30 – 33 – 37 – 38
– 42 – 43 – 47 – 48 – 49 – 52 – 54 – 56 –
57 – 59 – 62 – 63 – 64 – 67 – 68 – 69 – 71
– 74 –75 – 76 – 77 – 78 – 79 – 80 – 81 – 82
– 88 – 91 – 93 – 96 – 103 – 107
Public health issues and physiology:
13 – 15 – 25 – 28 – 29 – 34 – 35 – 36 – 41
– 46 – 47 – 54 – 55 – 58 – 61 – 63 – 72 –
73 – 82 – 84 – 85 – 94 – 95 – 99 – 101
Resúmenes Cortos
Congreso
México, 20 al 24 de Junio de 2006
Editores
Jochen Bundschuh
María Aurora Armienta
(Germany/Argentina/Costa Rica)
(Mexico)
Prosun Bhattacharya
Jörg Matschullat
(Sweden)
(Germany)
Peter Birkle
Ramiro Rodríguez
(Mexico)
(Mexico)

Arsenic Adsorption Technology- A Review of Long-Term

Transcripción

Documentos relacionados

conservacion del agua water conservation

Communication is key but what about Inspiration?