期刊
JOURNAL OF HYDROLOGY
卷 523, 期 -, 页码 128-138出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jhydrol.2015.01.035
关键词
Arsenic; Irrigation; Ferric reduction; Sulfate reduction; Geochemical inverse modeling
资金
- Ministry of Science and Technology of China [2012AA062602]
- National Natural Science Foundation of China [41202168, 41372254]
- center of Hydrogeology and Environmental Survey, CGS [12120113103700]
- Fundamental Research Fund for National Universities, China University of Geosciences (Wuhan)
Seasonal hydrochemical monitoring has been conducted at a well-known arsenic (As) contaminated site to understand the critical controlling processes on As mobilization and enrichment in groundwater. The hydrochemical results indicate that the water chemistry at the studied site is mainly controlled by evaporates dissolution, and redox reactions during irrigation and non-irrigation periods, respectively. The measured redox-sensitive components indicate that the groundwater experienced periodic redox changes from irrigation to non-irrigation periods and that an enhanced reducing environment prevailed during the non-irrigation period. The observed high As concentration and the strong positive correlation between As and Fe support the conclusion that the Fe oxides/hydroxides reduction and Fe sulfide oxidation releases As during the irrigation period. However, the relatively low As concentration and the close inverse correlation between As, Fe and SO42- show that Fe(III) and SO42- reduction accompanied by the formation of Fe sulfide precipitates, retains As during the non-irrigation periods. The geochemical inverse modeling performed for the selected wells confirms that Fe oxide/hydroxide and Fe sulfide dissolution as well as siderite precipitation are the dominant processes related to the mobilization of As during the water evolution from the pre-irrigation to irrigation period, while Fe sulfide precipitation immobilize As during the groundwater evolution from the irrigation to the post-irrigation period. In general, the combined results of the hydrochemical monitoring and the geochemical inverse modeling support the conclusion that the Fe(III)-SO42- redox cycling induced by periodic irrigation practices controls the mobilization of As in groundwater at this site. (C) 2015 Elsevier B.V. All rights reserved.
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