title: Sulfur Cycling-Related Biogeochemical Processes of Arsenic Mobilization in the Western Hetao Basin, China: Evidence from Multiple Isotope Approaches.
abstract: The role of sulfur cycling in arsenic behavior under reducing conditions is not well-understood in previous investigations. This study provides observations of sulfur and oxygen isotope fractionation in sulfate and evaluation of sulfur cycling-related biogeochemical processes controlling dissolved arsenic groundwater concentrations using multiple isotope approaches. As a typical basin hosting high arsenic groundwater, the western Hetao basin was selected as the study area. Results showed that, along the groundwater flow paths, groundwater δ34SSO4, δ18OSO4, and δ13CDOCincreased with increases in arsenic, dissolved iron, hydrogen sulfide and ammonium concentrations, while δ13CDICdecreased with decreasing Eh and sulfate/chloride. Bacterial sulfate reduction (BSR) was responsible for many of these observed changes. The δ34SSO4indicated that dissolved sulfate was mainly sourced from oxidative weathering of sulfides in upgradient alluvial fans. The high oxygen-sulfur isotope fractionation ratio (0.60) may result from both slow sulfate reduction rates and bacterial disproportionation of sulfur intermediates (BDSI). Data indicate that both the sulfide produced by BSR and the overall BDSI reduce arsenic-bearing iron(III) oxyhydroxides, leading to the release of arsenic into groundwater. These results suggest that sulfur-related biogeochemical processes are important in mobilizing arsenic in aquifer systems.
authors: State Key Laboratory of Biogeology and Environmental Geology, School of Water Resources and Environment, China University of Geosciences (Beijing) , Beijing 100083, China.
authors: Huaming
authors: H
authors: Guo
authors: State Key Laboratory of Biogeology and Environmental Geology, School of Water Resources and Environment, China University of Geosciences (Beijing) , Beijing 100083, China.
authors: Yinzhu
authors: Y
authors: Zhou
authors: State Key Laboratory of Biogeology and Environmental Geology, School of Water Resources and Environment, China University of Geosciences (Beijing) , Beijing 100083, China.
authors: Yongfeng
authors: Y
authors: Jia
authors: Institute of Applied Geosciences, Karlsruhe Institute of Technology , Karlsruhe 76131, Germany.
authors: Xiaohui
authors: X
authors: Tang
authors: State Key Laboratory of Biogeology and Environmental Geology, School of Water Resources and Environment, China University of Geosciences (Beijing) , Beijing 100083, China.
authors: Xiaofeng
authors: X
authors: Li
authors: State Key Laboratory of Biogeology and Environmental Geology, School of Water Resources and Environment, China University of Geosciences (Beijing) , Beijing 100083, China.
authors: Mengmeng
authors: M
authors: Shen
authors: The National Institute of Metrology , Beijing 100013, P.R. China.
authors: Hai
authors: H
authors: Lu
authors: Center for Hydrogeology and Environmental Geology, China Geological Survey , Baoding 071051, Hebei China.
authors: Shuangbao
authors: S
authors: Han
authors: The National Institute of Metrology , Beijing 100013, P.R. China.
authors: Chao
authors: C
authors: Wei
authors: Institute of Applied Geosciences, Karlsruhe Institute of Technology , Karlsruhe 76131, Germany.
authors: Stefan
authors: S
authors: Norra
authors: Center for Hydrogeology and Environmental Geology, China Geological Survey , Baoding 071051, Hebei China.
authors: Fucun
authors: F
authors: Zhang
mesh_terms: D001151:Arsenic; D002681:China; D005290:Ferric Compounds; D060587:Groundwater; D013455:Sulfur; D014874:Water Pollutants, Chemical
chemical_list: D005290:Ferric Compounds; D014874:Water Pollutants, Chemical; D013455:Sulfur; D001151:Arsenic