Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahak-ro, Yuseong-gu, Daejeon 34132, Republic of Korea.
Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahak-ro, Yuseong-gu, Daejeon 34132, Republic of Korea; Department of Environmental Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-gu, Cheongju, Chungbuk 28644, Republic of Korea.
J Hazard Mater. 2019 Oct 15;378:120745. doi: 10.1016/j.jhazmat.2019.120745. Epub 2019 Jun 6.
Changes in the saturation degree of aquifers control the geochemical reactions of redox-sensitive elements such as iron (Fe), sulfur (S), and arsenic (As). In this study, the effects of redox conditions and the presence of Fe and S on the behavior of As in a soil environment were investigated by observation in a batch experimental system. Arsenic was stable on Fe(III) solid surface in an oxidizing environment but was easily released into the aqueous phase following the reductive dissolution of Fe during an anoxic period. The alternating redox cycles led to a change in the concentrations of Fe, S, and As in both the aqueous and solid phases. The composition of Fe minerals changed to a less crystalline phase while that of solid phase As changed to a more reduced phase in both the As-contaminated natural soil and FeS-amended soil batch systems. This tendency was more prominent in the batch containing higher amounts of total Fe and S. These results show that a redox cycle can increase the possibility of As contamination of groundwater during dissolution and reprecipitation of Fe minerals and simultaneous microbial reduction of S and/or As species.
含水层饱和度的变化控制着铁（Fe）、硫（S）和砷（As）等氧化还原敏感元素的地球化学反应。在这项研究中，通过批实验系统观察，研究了氧化还原条件以及 Fe 和 S 的存在对土壤环境中 As 行为的影响。在氧化环境中，砷在 Fe(III)固体表面稳定，但在缺氧期 Fe 还原溶解后，很容易释放到水相。交替的氧化还原循环导致水相和固相中 Fe、S 和 As 的浓度发生变化。在受 As 污染的天然土壤和添加 FeS 的土壤批处理系统中，Fe 矿物的组成向非晶态转变，而固相 As 的组成向更还原态转变。在含有更多总 Fe 和 S 的批处理中，这种趋势更为明显。这些结果表明，在 Fe 矿物溶解和再沉淀以及同时发生的微生物还原 S 和/或 As 物种的过程中，氧化还原循环会增加地下水砷污染的可能性。
