title: Arsenic mobilization in aquifers of the southwest Songnen basin, P.R. China: evidences from chemical and isotopic characteristics.
abstract: High As groundwater has widely been found in the inland basins of China. Little is known about distribution and mobilization mechanisms of high As groundwater in the Songnen basin, where groundwater is the major source for drinking and irrigation. Eighty-seven groundwater samples, three surface water samples and sixty-three sediment samples were taken from the southwest of the Songnen basin, in order to investigate spatial distribution and constrains of groundwater As. Results showed that high As groundwater was generally of Na-Mg/Ca-HCO3 type, which had relatively low Eh values and neutral-weakly alkaline pH. High As groundwater was characterized by low concentrations of NO3(-) and SO4(2-), and high concentrations of Fe, Mn, and H2S. Around 65.5% of sampled shallow groundwater and 96% of sampled deep groundwater had As concentrations greater than 10 μg/L. Sediments had higher total As contents and higher Fe/Mn oxide-bound As contents in high As groundwater area than in the low As groundwater area. Distribution of groundwater As was dependent upon hydrogeologic settings, redox potential, microbial degradation of organic carbon, and precipitation of pyrite, siderite, and calcite. Along the groundwater flow path, As concentration showed an increasing trend. High As groundwater was mainly distributed in the low-lying areas. Reducing conditions were the major causes for As mobilization in the aquifers, which led to more As released from the sediments with higher contents of Fe/Mn oxide-bound As in higher As groundwater area. Results of (13)CDOC and (13)CDIC showed that dissimilatory Fe(III) reduction coupled with microbial degradation of dissolved organic carbon would be related to As mobilization in the aquifers. Although both Fe and As were released during these redox processes, pyrite, siderite and calcite precipitation would be the sink of dissolved As, which resulted in weak correlation between dissolved Fe and As.
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; MOE Key Laboratory of Groundwater Circulation & Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China. Electronic address: hmguo@cugb.edu.cn.
authors.forename: Huaming
authors.initials: H
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; MOE Key Laboratory of Groundwater Circulation & Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Di
authors.initials: D
authors.lastname: Zhang
authors.affiliation: China Geological Survey, 24 Huangsi Dajie, Xicheng District, Beijing 100037, PR China.
authors.forename: Dongguang
authors.initials: D
authors.lastname: Wen
authors.affiliation: MOE Key Laboratory of Groundwater Circulation & Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.affiliation: MOE Key Laboratory of Groundwater Circulation & Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Ni
authors.affiliation: MOE Key Laboratory of Groundwater Circulation & Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Yuxiao
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: MOE Key Laboratory of Groundwater Circulation & Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Guo
authors.affiliation: MOE Key Laboratory of Groundwater Circulation & Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Fulan
authors.initials: F
authors.lastname: Li
authors.affiliation: MOE Key Laboratory of Groundwater Circulation & Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zheng
authors.affiliation: MOE Key Laboratory of Groundwater Circulation & Environment Evolution and School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
authors.forename: Yinzhu
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D001151:Arsenic / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D060587:Groundwater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D001151:Arsenic
keywords: Aquifers; Arsenic species; Dissolved organic carbon; Sequential extraction; Stable isotopes