https://scholars.lib.ntu.edu.tw/handle/123456789/393651
標題: | Effect of sulfidogenesis cycling on the biogeochemical process in arsenic-enriched aquifers in the Lanyang Plain of Taiwan: Evidence from a sulfur isotope study | 作者: | CHEN-WUING LIU PEI-LING WANG |
關鍵字: | Arsenic; Binary mixing model; Groundwater; Sulfur and oxygen isotope | 公開日期: | 2015 | 卷: | 528 | 起(迄)頁: | 523-536 | 來源出版物: | Journal of Hydrology | 摘要: | This study evaluated the biogeochemical interactions between arsenic (As) and sulfur (S) in groundwater to understand the natural and anthropogenic influences of S redox processes on As mobilization in the Lanyang Plain, Taiwan. Cl- and the sulfate isotopic composition δ34S[SO4] were selected as conservative tracers. River water and saline seawater were considered as end members in the binary mixing model. Thirty-two groundwater samples were divided into four types of groundwater (I, pyrite-oxidation; II, iron- and sulfate-reducing; III, sulfate-reducing; and IV, anthropogenic and others). The binary mixing model coupled with discriminant analysis was applied to yield a classification with 97% correctness, indicating that the DO/ORP values and δ34S[SO4] and Fe2+ concentrations are effective redox-sensitive indicators. Type I groundwater is mostly located in a mountainous recharge area where pyrite oxidation is the major geochemical process. A high 18O enrichment factor ε[SO4-H2O] and high 34S enrichment factor ε34S[FeS2-SO4] indicate that disproportionation and dissimilatory sulfate reduction are both involved in Type II and Type III groundwater. The process of bacterial sulfate reduction may coprecipitate and sequester As, a mechanism that is unlikely to occur in Type II groundwater. The presence of high As and Fe2+ concentrations and enriched δ34S[SO4] in Type II groundwater suggest that biogeochemical reactions occurred under anaerobic conditions. The reductive dissolution of As-bearing Fe oxyhydroxides together with microbial disproportionation of sulfur explains the substantial correlations among the high As concentration and enriched δ34S[SO4] and Fe2+ concentrations in the iron- and sulfate-reducing zone (Type II). The As concentration in Type III groundwater (sulfate-reducing) is lower than that in Type II groundwater because of bacterial sulfate reduction and coprecipitation with As. Furthermore, the dissolution of sulfate minerals is not the major source of aqueous SO4, based on the sulfur isotopic composition of solid-phase sulfate (δ34S[sulfate mineral]). Finally, the anthropogenic influence of fertilizers with wide S isotopic ranges is proposed as the plausible sulfate budget in Type IV groundwater. The results of this study suggest that the As release into groundwater involves the reductive dissolution of As-bearing Fe-hydroxides, bacterial sulfate reduction, and microbial disproportionation in the Lanyang Plain. © 2015 Elsevier B.V. |
URI: | http://www.scopus.com/inward/record.url?eid=2-s2.0-84936852199&partnerID=MN8TOARS http://scholars.lib.ntu.edu.tw/handle/123456789/393651 |
DOI: | 10.1016/j.jhydrol.2015.06.033 | SDG/關鍵字: | Aquifers; Arsenic; Bins; Biogeochemistry; Budget control; Discriminant analysis; Dissolution; Groundwater; Groundwater resources; Hydrogeology; Isotopes; Mixing; Pyrites; Reduction; Saline water; Sulfur; Sulfur compounds; Anthropogenic influence; Bacterial sulfate reduction; Binary mixing; Biogeochemical interactions; Biogeochemical process; Biogeochemical reactions; Oxygen isotopes; Reductive dissolution; Sulfate minerals; anoxic conditions; anthropogenic effect; aquifer; arsenic; biogeochemical cycle; concentration (composition); fertilizer; groundwater; iron hydroxide; isotopic composition; river water; sulfur; Lanyang Plain; Taiwan; Bacteria (microorganisms) |
顯示於: | 生物環境系統工程學系 |
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