title: δ34S and δ18O of dissolved sulfate as biotic tracer of biogeochemical influences on arsenic mobilization in groundwater in the Hetao Plain, Inner Mongolia, China.
abstract: Environmental isotopology of sulfur and oxygen of dissolved sulfate in groundwater was conducted in the Hetao Plain, northwestern China, aiming to better understand the processes controlling arsenic mobilization in arsenic-rich aqueous systems. A total of 22 groundwater samples were collected from domestic wells in the Hetao Plain. Arsenic concentrations ranged from 11.0 to 388 μg/L. The δ(34)S-SO4 and δ(18)O-SO4 values of dissolved sulfate covered a range from +1.48 to +22.4‰ and +8.17‰ to +14.8‰ in groundwater, respectively. The wide range of δ(34)S-SO4 values reflected either an input of different sources of sulfate, such as gypsum dissolution and fertilizer application, or a modification from biogeochemical process of bacterial sulfate reduction. The positive correlation between δ(34)S-SO4 and arsenic concentrations suggested that bacteria mediated processes played an important role in the mobilization of arsenic. The δ(18)O-SO4 values correlated non-linearly with δ(34)S-SO4, but within a relatively narrow range (+8.17 to +14.8‰), implying that complexities inherent in the sulfate-oxygen (O-SO4(2-)) origins, for instance, water-derived oxygen (O-H2O), molecular oxygen (O-O2) and isotope exchanging with dissolved oxides, are accounted for oxygen isotope composition of dissolved sulfate in groundwater in the Hetao Plain.
authors.affiliation: School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan, 430074, China.
authors.forename: M D
authors.initials: MD
authors.lastname: Li
authors.forename: Y X
authors.initials: YX
authors.lastname: Wang
authors.forename: P
authors.initials: P
authors.lastname: Li
authors.forename: Y M
authors.initials: YM
authors.lastname: Deng
authors.forename: X J
authors.initials: XJ
authors.lastname: Xie
mesh_terms: D001151:Arsenic / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring / Q000379:methods*; D060587:Groundwater / Q000737:chemistry*; D010103:Oxygen Isotopes / Q000032:analysis; D013431:Sulfates / Q000032:analysis; D013460:Sulfur Isotopes / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D010103:Oxygen Isotopes; D013431:Sulfates; D013460:Sulfur Isotopes; D014874:Water Pollutants, Chemical; D001151:Arsenic