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Selenium speciation in seleniferous agricultural soils under different cropping systems using sequential extraction
Hai-Bo Qin1, Jian-Ming Zhu2, Zhi-Qing Lin3
1State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
Environmental Pollution (Barking, Essex : 1987)
|March 19, 2017
Summary
Soil selenium speciation is crucial for environmental understanding. Organic selenium dominates agricultural soils, influenced by cropping systems, impacting plant uptake and potential toxicity.
Area of Science:
- Environmental Chemistry
- Soil Science
- Geochemistry
Background:
- Selenium (Se) speciation in soil is vital for assessing its environmental fate, including solubility, mobility, bioavailability, and toxicity.
- Understanding Se speciation is critical in agricultural soils, especially in seleniferous regions, to manage potential risks and benefits.
Purpose of the Study:
- To investigate selenium fractionation and chemical speciation in agricultural soils from seleniferous areas.
- To compare and combine sequential extraction and X-ray absorption near-edge structure (XANES) spectroscopy for reliable Se speciation analysis.
Main Methods:
- Utilized sequential extraction to fractionate soil samples.
- Employed X-ray absorption near-edge structure (XANES) spectroscopy for quantitative Se speciation.
- Integrated data from both methods for robust speciation characterization.
Main Results:
- Dominant forms of selenium in seleniferous agricultural soils were organic Se (56-81%) and Se(IV) (19-44%).
- The proportion of organic Se decreased in the order: paddy soil (81%) > uncultivated soil (69-73%) > upland soil (56-63%).
- Se speciation was significantly influenced by different cropping systems, with organic Se likely originating from plant litter.
Conclusions:
- The combination of sequential extraction and XANES is a reliable method for characterizing soil Se speciation.
- Cropping systems significantly affect selenium speciation in agricultural soils.
- Elevated organic Se may lead to increased Se accumulation in crops and potential chronic toxicity in humans.
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