Arsenic behavior across soil-water interfaces in paddy soils: Coupling, decoupling and speciation

文献类型： 外文期刊

第一作者： Yuan, Zhao-Feng

作者： Yuan, Zhao-Feng;Gustave, Williamson;Ren, Yuxiang;Chen, Zheng;Yuan, Zhao-Feng;Gustave, Williamson;Gustave, Williamson;Boyle, John;Sekar, Raju;Bridge, Jonathan;Tang, Xianjin;Guo, Bin

作者机构：

关键词： Arsenic; Iron; Profile; Paddy soil; Coupling; Decoupling

期刊名称：CHEMOSPHERE （ 影响因子：5.778； 五年影响因子：5.705 ）

ISSN： 0045-6535

年卷期： 2021 年 269 卷

页码：

收录情况： SCI

摘要： The sharp redox gradient at soil-water interfaces (SWI) plays a key role in controlling arsenic (As) translocation and transformation in paddy soils. When Eh drops, As is released to porewater from solid iron (Fe) and manganese (Mn) minerals and reduced to arsenite. However, the coupling or decoupling processes operating within the redox gradient at the SWI in flooded paddy soils remain poorly constrained due to the lack of direct evidence. In this paper, we reported the mm-scale mapping of Fe, As and other associated elements across the redox gradient in the SWI of five different paddy soils. The results showed a strong positive linear relationship between dissolved Fe, Mn, As, and phosphorus (P) in 4 out of the 5 paddy soils, indicating the general coupling of these elements. However, decoupling of Fe, Mn and As was observed in one of the paddy soils. In this soil, distinct releasing profiles of Mn, As and Fe were observed, and the releasing order followed the redox ladder. Further investigation of As species showed the ratio of arsenite to total As dropped from 100% to 75.5% and then kept stable along depth of the soil profile, which indicates a dynamic equilibrium between arsenite oxidization and arsenate reduction. This study provides direct evidence of multi-elements' interaction along redox gradient of SWI in paddy soils. (C) 2020 Elsevier Ltd. All rights reserved.

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