Nguyen Kim Phuong, Itoi Ryuichi
Department of Geo-environment, Faculty of Geology and Petroleum Engineering, HCMC University of Technology, 268 Ly Thuong Kiet Street, Ward 14, District 10, Ho Chi Minh City, Vietnam.
J Contam Hydrol. 2009 Jan 7;103(1-2):58-69. doi: 10.1016/j.jconhyd.2008.09.005. Epub 2008 Sep 23.
In order to elucidate the arsenic source and its release mechanism into groundwater in the Mekong Delta, Vietnam, groundwater samples were collected from wells at different depths (20 to 440 m) and core samples (from 20 to 265 m depth) were analyzed. Based on the analytical results for groundwater and core samples, the As source in groundwater is considered to be pyrite (FeS(2)) in acid sulfate soil (ASS) under oxidizing conditions and hydrous ferric oxide (Fe(OH)(3)) under reducing conditions. Geochemical modeling demonstrated that As(III) is the dominant species and the presence of As-bearing sulfides, Fe-bearing sulfides and oxides phases may locally act as potential sinks for As. From variation between Fe and As concentrations in groundwater samples, the release mechanism of As is: dissolution of Fe(OH)(3) containing As under reducing conditions and oxidative decomposition of FeS(2) containing As under oxidizing conditions.
为了阐明越南湄公河三角洲地区砷的来源及其向地下水的释放机制，从不同深度（20至440米）的井中采集了地下水样本，并对岩芯样本（深度为20至265米）进行了分析。根据地下水和岩芯样本的分析结果，认为氧化条件下酸性硫酸盐土壤（ASS）中的黄铁矿（FeS₂）以及还原条件下的水合氧化铁（Fe(OH)₃）是地下水中砷的来源。地球化学模型表明，As(III)是主要形态，含砷硫化物、含铁硫化物和氧化物相的存在可能在局部充当砷的潜在汇。根据地下水样本中Fe和As浓度的变化，砷的释放机制为：还原条件下含砷Fe(OH)₃的溶解以及氧化条件下含砷FeS₂的氧化分解。
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