Redox transformation of soil minerals and arsenic in arsenic-contaminated soil under cycling redox conditions

• Published in: Journal of hazardous materials 2019-10, Vol.378, p.120745-120745, Article 120745
• Main Authors: Han, Young-Soo, Park, Ji-Hyun, Kim, So-Jeong, Jeong, Hoon Y., Ahn, Joo Sung
• Format: Article
• Language: English
• Subjects: Arsenic; Fe minerals; FeS; Redox cycling; Sulfate-reducing
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.120745

•Mobility of As increases in the presence of Fe(II) under anoxic conditions•As mobility varies due to the dissolution or re-precipitation of Fe minerals•Repetition of redox cycle may cause As to adversely affect the environment 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.