Silene vulgaris rhizospere-induced chemical changes in pore

Silene vulgaris rhizospere-induced chemical changes in pore

Silene vulgaris rhizospere-induced chemical changes in pore
water samples from chromium polluted soils.
A.E. Pradas del Real1*, M.J. Gismera2, P. García-Gonzalo1, M.C. Lobo1, A. PerezSanz1.
1
Dpto. de Investigación Agroambiental. IMIDRA, Finca “El Encín”, A-II Km. 38.200,
28800, Alcalá de Henares, Madrid, SPAIN
2
Dpto de Química Analítica y Análisis Instrumental, Facultad de Ciencias, C/Francisco
Tomás y Valiente 7. Universidad Autónoma de Madrid, 28049 Madrid, SPAIN.
*
Presenting author contact: [email protected]
Plant roots modify the biochemical characteristic of rhizosphere region
depending on their root exudation, nutrient acquisition strategies and root system
architecture. By these processes plant roots may change the concentration of
bioavailable and soluble metals to control metal uptake and to improve
phytomanagement tecnologies.
A pot experiment was performed to study the influence of Silene vulgaris roots
on biochemical characteristics and metal bioavailability in pore water samples from
chromium polluted soils. Plastic pots were filled with 17 kg of two agricultural soils from
“Alcalá de Henares” (clay; pH=8.1; O.M.=0.66%) and “El Escorial“(sandy loam;
pH=6.62; O.M.=2.67%), both located in Madrid (Spain). Degradation of soil caused by
chromium industrial activities was simulated by spilling K2Cr2O4 solution (1000mgCr·L-1)
or ammended with Cr enriched sludge (1050 mgCr·Kg-1) to reach a chromium final
concentration in pots of 100mg·Kg soil-1. Two genotypes of S.vulgaris (SV21 and
SV38) were used to evaluate the vegetation influence. Soil controls without plant were
also included. Pore water samples from rhizosphere were extracted by using Rhizon
soil moisture samplers (Rhizon SMS 19.21). After 6 months of plant growing, organic
acid and total Cr concentrations, pH, Electrical Conductivity (EC) and Total Organic
Carbon (TOC) were determined in pore water samples.
Plant, soil characteristics, and the source of Cr significantly influenced the
evaluated parameters. The concentration of organic acids decreases in pore water
samples from uncontaminated soil “El Escorial” and cultivated with S.vulgaris. On
contrary, this concentration increases when the pore water samples were taken from
similar treatments, but in soil from “Alcala de Henares”, poor in organic matter and
more basic than “El Escorial”. In both soils polluted with Cr and grown with plants,
organic acid concentration increased in pore water samples. That indicates S.vulgaris
might release organic acids into the rhizosphere to undergo adverse conditions. Plant
presence also increased Cr bioavailabilty in pore water samples from soil “Alcalá de
Henares”, which is accompanied by an increase of pH and TOC, probably due to
complex reaction between soluble organic Cr and TOC induced by roots. S.vulgaris
roots influenced pH, TOC and Cr concentration in the rhizosphere soil solutions which
might be considered in phytomanagement processes.