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Integrated Field Lysimetry and Porewater Sampling for Evaluation of Chemical Mobility in Soils and Established Vegetation
Published on: July 4, 2014
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Leaching effect on arsenic mobility in agricultural soils
Barbora Dousova1, Frantisek Buzek2, Miloslav Lhotka1
1University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic.
Journal of Hazardous Materials
|January 20, 2016
Summary
Soil arsenic stability was investigated through long-term leaching experiments. Arsenic release peaked initially, then stabilized, with soil properties like hydraulic conductivity and particle size primarily influencing arsenic retention.
Area of Science:
- Environmental Science
- Soil Science
- Geochemistry
Background:
- Arsenic (As) contamination in agricultural soils poses risks to food safety and environmental health.
- Understanding arsenic's long-term behavior, particularly its mobility and accumulation under leaching conditions, is crucial for risk assessment and management.
Purpose of the Study:
- To evaluate the stability and mobility of soil arsenic during long-term leaching with arsenic-free rainwater.
- To investigate the factors controlling arsenic release, accumulation, and transformation in different soil types.
Main Methods:
- Soil columns were leached with arsenic-free and arsenic-enriched rainwater to simulate natural conditions.
- Arsenic flow, release kinetics, and accumulation were monitored over time.
- Sequential extraction (SEP) was used to determine the distribution of arsenic species.
- Soil properties such as saturated hydraulic conductivity (Ksat), particle size, clay fraction, free iron oxides, organic matter (OM), and specific surface area (SBET) were analyzed.
Main Results:
- Arsenic release exhibited an initial peak followed by a tendency to equilibrate, indicating a dynamic release process.
- Saturated hydraulic conductivity (Ksat) and free iron oxides were key factors controlling the amount of released arsenic.
- The kinetics of arsenic leaching correlated with organic matter content.
- Overall arsenic stability and accumulation were predominantly influenced by soil physical properties (Ksat, particle size, clay fraction).
- Chemical composition and surface properties had marginal significance on arsenic retention.
- Sequential extraction revealed negligible transformation (<12%) of arsenic species in the upper soil layers.
Conclusions:
- Soil properties, particularly Ksat and particle size distribution, are the primary determinants of arsenic stability and accumulation under leaching.
- While initial arsenic release can be significant, soils tend towards a stable state over time.
- Arsenic species showed remarkable stability within the soil matrix, with minimal transformation observed.
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