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Redox-dependent effects of phosphate on arsenic speciation in paddy soils.
Environmental Pollution ( IF 7.6 ) Pub Date : 2020-05-11 , DOI: 10.1016/j.envpol.2020.114783 Yingxuan Deng 1 , Liping Weng 2 , Yongtao Li 3 , Yali Chen 1 , Jie Ma 1
Environmental Pollution ( IF 7.6 ) Pub Date : 2020-05-11 , DOI: 10.1016/j.envpol.2020.114783 Yingxuan Deng 1 , Liping Weng 2 , Yongtao Li 3 , Yali Chen 1 , Jie Ma 1
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Evaluating speciation of arsenic (As) is essential to assess its risk in paddy soils. In this study, effects of phosphate on speciation of As in six paddy soils differing in redox status were studied over a range of pH (pH 3-9) and different background calcium (Ca) levels by batch adsorption experiments and speciation modeling. Contrasting effects of phosphate on As speciation were observed in suboxic and anoxic soils. Under suboxic conditions, phosphate inhibited Fe and As reduction probably due to stabilization of Fe-(hydr)oxides, but increased soluble As(V) concentration as a result of competitive adsorption between As(V) and phosphate. In anoxic soils, phosphate stimulated Fe and As reduction and caused increases of As(III) in soil solution under both acidic and neutral/alkaline pH. The LCD (Ligand and Charge Distribution) and NOM-CD (Natural Organic Matter-Charge Distribution) model can describe effects of pH, calcium and phosphate on As speciation in these paddy soils. The results suggest that phosphate fertilization may decrease (at low pH) or increase (at neutral/alkaline pH) As mobility in paddy soils under (sub)oxic conditions, but under anoxic conditions and in phosphorus deficient soils phosphate fertilization may strongly mobilize As by promoting microbial activities.
中文翻译：
磷酸盐对稻田土壤砷形态的氧化还原依赖性作用。
评估砷（As）的形态对于评估稻田土壤中的砷风险至关重要。在这项研究中，通过分批吸附实验和形态模拟，研究了磷酸盐在6种氧化还原状态不同的稻田土壤中砷形态的影响，其范围为pH（pH 3-9）和不同背景钙（Ca）水平。在低氧和缺氧的土壤中观察到了磷酸盐对砷形态的影响。在低氧条件下，磷酸盐抑制了Fe和As的还原，这可能是由于Fe-（氢氧化）氧化物的稳定所致，但是由于As（V）与磷酸盐之间的竞争性吸附，增加了可溶性As（V）的浓度。在缺氧的土壤中，磷酸盐在酸性和中性/碱性pH值下都刺激Fe和As的还原，并导致土壤溶液中As（III）的增加。LCD（配体和电荷分布）和NOM-CD（天然有机物电荷分布）模型可以描述pH，钙和磷酸盐对这些水稻土中As形态的影响。结果表明，磷肥在低氧条件下可降低（在低pH值下）或增加（中性/碱性pH值）下的稻田土壤中的迁移率，但在缺氧条件下和缺磷的土壤中，磷肥可通过促进微生物活动。
更新日期：2020-05-11
中文翻译：
磷酸盐对稻田土壤砷形态的氧化还原依赖性作用。
评估砷（As）的形态对于评估稻田土壤中的砷风险至关重要。在这项研究中，通过分批吸附实验和形态模拟，研究了磷酸盐在6种氧化还原状态不同的稻田土壤中砷形态的影响，其范围为pH（pH 3-9）和不同背景钙（Ca）水平。在低氧和缺氧的土壤中观察到了磷酸盐对砷形态的影响。在低氧条件下，磷酸盐抑制了Fe和As的还原，这可能是由于Fe-（氢氧化）氧化物的稳定所致，但是由于As（V）与磷酸盐之间的竞争性吸附，增加了可溶性As（V）的浓度。在缺氧的土壤中，磷酸盐在酸性和中性/碱性pH值下都刺激Fe和As的还原，并导致土壤溶液中As（III）的增加。LCD（配体和电荷分布）和NOM-CD（天然有机物电荷分布）模型可以描述pH，钙和磷酸盐对这些水稻土中As形态的影响。结果表明，磷肥在低氧条件下可降低（在低pH值下）或增加（中性/碱性pH值）下的稻田土壤中的迁移率，但在缺氧条件下和缺磷的土壤中，磷肥可通过促进微生物活动。
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