title: The effect of microbial sulfidogenesis on the stability of As-Fe coprecipitate with low Fe/As molar ratio under anaerobic conditions.
abstract: The effect of microbial sulfidogenesis on As transformation and mobilization in solid phase with low Fe/As ratio is still not well known. In this study, microbial transformation and mobilization of As in the As-Fe coprecipitate with different sulfate levels were investigated using chemical extraction and K-edge XANES of As and S. Results showed that approximately 2.7, 24.4, and 83.7 % of total As were released into the aqueous phase in the low-, mid-, and high-sulfate treatments, respectively, indicating that the presence of large amounts of sulfate could enhance microbial arsenic mobilization in the As-Fe coprecipitate. In the low-sulfate treatment, As mobilization was primarily attributed to the reductive dissolution of the Fe (oxy)hydroxides and the As reduction and desorption. In the mid- and high-sulfate treatments, the reduction of arsenate and ferric iron was significantly enhanced. Complete ferric iron reduction was observed in the solid phase, implying that Fe (oxy)hydroxide was transformed to secondary minerals and may be the one of the primary causes for the enhanced As mobilization. Thermodynamic calculations predicted the formation of thioarsenite species after 35 days of incubation based on the concentration of dissolved As(III) and S(-II). Since thioarsenic species is more mobile, its formation may be one of the most important factors enhancing the As release in the high-sulfate system. The result of this study is of significance to completely predict the environmental behavior of As associated with Fe (hydr)oxides in the presence of microbial sulfidogenesis under anoxic conditions.
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China. wangshaofeng@iae.ac.cn.
authors.forename: Shaofeng
authors.initials: S
authors.lastname: Wang
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.|University of Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Xin Yu
authors.initials: XY
authors.lastname: He
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
authors.forename: Rongrong
authors.initials: R
authors.lastname: Pan
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
authors.forename: Liying
authors.initials: L
authors.lastname: Xu
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Jia
mesh_terms: D000693:Anaerobiosis; D001151:Arsenic / Q000737:chemistry / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D011232:Chemical Precipitation; D004305:Dose-Response Relationship, Drug; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D013431:Sulfates; D013455:Sulfur; D007501:Iron; D001151:Arsenic
keywords: Arsenic mobilization; Arsenic-bearing solid waste; Microbial reduction of As, Fe, and S; Sulfate level