Factors and pathways regulating the release and transformation of arsenic mediated by reduction processes of dissimilated iron and sulfate

Wenjing Shi; Wenjie Song; Jinli Zheng; Yu Luo; Geer Qile; Sijie Lü; Xiangmeng Lü; Bin Zhou; Changwei Lü; Jiang He

doi:10.1016/j.scitotenv.2020.144697

Factors and pathways regulating the release and transformation of arsenic mediated by reduction processes of dissimilated iron and sulfate

Sci Total Environ. 2021 May 10:768:144697. doi: 10.1016/j.scitotenv.2020.144697. Epub 2021 Jan 9.

Authors

Wenjing Shi¹, Wenjie Song², Jinli Zheng¹, Yu Luo¹, Geer Qile¹, Sijie Lü¹, Xiangmeng Lü¹, Bin Zhou³, Changwei Lü⁴, Jiang He⁵

Affiliations

¹ School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China.
² Pioneer College, Inner Mongolia University, Hohhot 010021, China.
³ Tianjin Academy of Eco-Environmental Sciences, Tianjin 300191, China.
⁴ School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China; Institute of Environmental Geology, Inner Mongolia University, Hohhot 010021, China. Electronic address: lcw2008@imu.edu.cn.
⁵ School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China; Institute of Environmental Geology, Inner Mongolia University, Hohhot 010021, China. Electronic address: ndjhe@imu.edu.cn.

PMID: 33454476
DOI: 10.1016/j.scitotenv.2020.144697

Abstract

The driving process and explanatory factors regulating the transformation and migration of arsenic (As) mediated by dissimilatory iron reducing bacteria (DFeRB) and sulfate reducing bacteria (SRB) remain poorly understood. The novelty of this study is to explore the driving process and key environmental factors governing As mobilization mediated by DFeRB and SRB based on continuous As speciation and environmental parameter monitoring in a sediment-water system. The results illustrate the reduction process mediated by DFeRB and SRB significantly promotes the reduction of As(V) and the endogenous release of As. However, in the DFeRB and SRB mediated reductions, the main driving process and key explanatory factors that dominate the As mobility are significantly different. DFeRB has significant effects on the reductive dissolution and re-distribution of Fe(III) oxyhydroxides and As-containing Fe(III) minerals and on adsorption-desorption, which in turn influenced the transformation of iron species and the release and ecotoxicity of As. Meanwhile, the environmental factors that affect As mobility depend on Fe²⁺ and Fe³⁺ in DFeRB-induced reduction, presenting two main pathways: the process of As mobilization mediated by DFeRB, and the process influenced by the inorganic phosphorus involved in the competitive adsorption and anion exchange. Significantly different from DFeRB, the effects of SRB on As behavior mainly occur by influencing the adsorbed As, pyrite, and As sulfides in the sediments and through the formation of sulfides during the sulfate reduction. The main pathways of As mobilization reflect the direct effects of SRB, S^2-, and Fe²⁺. In addition, the role of NH₄⁺-N in the driving process of As mobility is more pronounced in SRB-induced reduction. NO₃^--N is an essential factor affecting As mobility, but the effects of NO₃^--N on As lead to non-significant pathways. This work provides insights into the environmental effects of DFeRB and SRB on the biogeochemical cycle of As.

Keywords: As; DFeRB and SRB; Driving process; Environmental explanatory factors; Transformation and migration.