Effects of organic sulfur and arsenite/dissolved organic matter ratios on arsenite complexation with dissolved organic matter
Effects of organic sulfur and arsenite/dissolved organic matter ratios on arsenite complexation with dissolved organic matter
复制标题
有机硫和亚砷酸盐/溶解有机物比例对亚砷酸盐与溶解有机物络合的影响
DOI：
10.1016/j.chemosphere.2022.134770
复制
发表时间：
2022
期刊：
影响因子：
8.8
通讯作者：
Reid, Matthew C.
中科院分区：
文献类型：
--
作者：
Abu-Ali, Lena;Yoon, Hyun;Reid, Matthew C.
砷（As）在土壤-水系统中的形态和归宿是一个非常感兴趣的话题，部分原因是越来越多的人意识到水稻吸收As作为一个重要的人类暴露途径。稻田和其他湿地土壤富含溶解性有机质（DOM），导致As/DOM比值通常低于地下水含水层或已被用于许多实验室研究的As-DOM相互作用。在这方面的贡献，我们评估亚砷酸盐（As（III））结合到7个不同的DOM样品在湿地孔隙沃茨相关的As/DOM比例，并探讨与高水平的As（III）-DOM络合的DOM样品的化学性质。我们综合了DOM化学性质的湿化学分析、透析平衡实验和双中心配体结合模型的数据，结果表明，在某些DOM样品中，15-60%的As（III）可以与DOM结合，其环境相关的As/DOM比为0.0032-0.016 μmol As/mmol C。结合随着As（III）/DOM比率的增加而降低。DOM样品的有机硫（索尔格）含量与As（III）-DOM络合水平和“强”结合位点密度密切相关，这与硫醇是天然有机物中As（III）的强结合配体的理论一致。最后是一个完整的细胞。大肠杆菌生物传感器测定表明，DOM样品最有效的络合As（III）也导致降低微生物的As（III）的吸收在低的As/DOC的比例。这项工作表明，自然发生的变化，在Sorgcontent的DOM有显着的影响As（III）结合DOM，并有影响As（III）的微生物。
The speciation and fate of arsenic (As) in soil-water systems is a topic of great interest, in part due to growing awareness of As uptake into rice as an important human exposure pathway to As. Rice paddy and other wetland soils are rich in dissolved organic matter (DOM), leading to As/DOM ratios that are typically lower than those in groundwater aquifers or that have been used in many laboratory studies of As-DOM interactions. In this contribution, we evaluate arsenite (As(III)) binding to seven different DOM samples at As/DOM ratios relevant for wetland pore waters, and explore the chemical properties of the DOM samples associated with high levels of As(III)-DOM complexation. We integrate data from wet chemical analysis of DOM chemical properties, dialysis equilibrium experiments, and two-site ligand binding models to show that in some DOM samples, 15–60% of As(III) can be bound to DOM at environmentally-relevant As/DOM ratios of 0.0032–0.016 μmol As/mmol C. Binding decreases as the As(III)/DOM ratio increases. The organic sulfur (Sorg) content of the DOM samples was strongly correlated with levels of As(III)-DOM complexation and “strong” binding site densities, consistent with theories that thiols are strong binding ligands for As(III) in natural organic matter. Finally, a whole-cellE. colibiosensor assay was used to show that DOM samples most effective at complexing As(III) also led to decreased microbial As(III) uptake at low As/DOC ratios. This work demonstrates that naturally-occurring variations in the Sorgcontent of DOM has a significant impact on As(III) binding to DOM, and has implications for As(III) availability to microorganisms.