WP2. Effect of agricultural practices on arsenic concentration, bioavailability and toxicity in water and soil
(Leader: BRGM, Partners: GEOS, LEB, KTH)
Objective
The objective of WP2 is to quantify the effect of chemical or organic fertilizers and liming on the behaviour of As, transfer toward crop plants and transfer towards groundwater or surface water.
Approach
Task 2.1.Characterization of As bioavailability and mobility on targeted sites (BRGM, GEOS)
Plots on contaminated sites will be selected and inventory of agricultural practices will be conducted. Soil sampling on target sites for laboratory tests will be made (input to WP3).
As speciation in soils and water will be characterised and As bioavailability will be evaluated from analyses of interstitial water. Estimation of As mobility through groundwater will be evaluated on water samples and geochemical modelling. Transfer, bioavailability and the toxicity of As from soils will be assessed by measuring the bioaccumulation in the aerial part of plants grown on soils and by analysing the lipidic bioindicator on the same plants. Comparison between plots will contribute to evaluate the impact of As speciation and agricultural practices on As fate.
Task 2.2 Effects of amendments on As bioavailability and mobility: microcosms (BRGM)
Microcosms experiments: soils will be mixed with fertilizers (NPK) and soil amendments such as liming, organic/green manure selected as used in the region of the site. The effect on soil geochemistry (solid and water phase), with extended speciation of As, and biogeochemistry (microbial bio-indicators) will be determined. Identification of the mechanisms will be done by using geochemical modelling to simulate experimental results and to predict As speciation and mobility.
Task 2.3 Effects of amendments on arsenic toxicity (LEB, BRGM)
Experiments in pots: crop plants specific to each site will be seeded in pots. The different agricultural amendments specific of the sites will be tested.
The Lipidic bio-indicator will be measured in the young plants. Arsenic transfer towards plants will be determined by analysis and speciation of As in the edible parts of the plants (ex. grain of cereals).
Arsenic migration to water will be determined by sampling and analysis of the pore water (with extended As speciation), and microbial bio-indicators will be applied.
Task 2.4 Mass balance and hydrogeochemical modelling (BRGM, KTH)
The data from previous tasks will be integrated to predict the mass balance of the fate of As, initially present in the soil, including the temporal factor, taking advantage of historical data on As input and the biogeochemical mechanisms highlighted during the lab experiments. The data acquired in WP3 will be made available for WP4 and WP5.
Outputs
- Effect of agricultural amendments on speciation and bioavailability of As;
- Effect of agricultural amendments on transfer and toxicity of As toward plants and groundwater;
- Mass balance of As transfer according to agricultural amendment
