河套平原西部地下水砷富集机制研究  

Arsenic enrichment mechanism of groundwater in the western Hetao Plain

作　　者：闫雅妮 李海青 文新月 谢文龙 张俊文 赵志琦 YAN Ya-ni;LI Hai-qing;WEN Xin-yue;XIE Wen-long;ZHANG Jun-wen;ZHAO Zhi-qi(School of Earth Science and Resources,Chang′an University,Xi′an 710054,China;Organizations of Coal Geology and Geophysical Survey in Qinghai,Xining 810000,China)

机构地区：[1]长安大学地球科学与资源学院,西安710054 [2]青海煤炭地质物探测量队,西宁810000

出　　处：《矿物岩石地球化学通报》2023年第2期289-297,共9页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：陕西省自然科学基金资助项目(2022JZ-19,2022JQ-229);中央高校基本科研业务费专项资金——长安大学优秀博士学位论文培育项目(300102272716)。

摘　　要：干旱内陆盆地高砷含量的地下水威胁着当地饮用水安全,其形成机制尚不完全清楚。为厘清这类高砷地下水的形成机制,本文以河套平原西部地下水为研究对象,分析其中As等部分氧化还原敏感元素含量和氢、氧同位素组成(δD和δ^(18)O)。结果表明,地下水样的As的质量浓度为1.5~155μg/L(均值为36.7μg/L),超半数样品超过10μg/L,主要分布于盆地中部的浅层含水层。水样的氢、氧同位素组成和离子间的相关性分析表明,虽然蒸发浓缩作用导致地下水富集Na+和Cl-,但对As的富集影响不显著;在偏碱性环境中因解吸附作用产生的As进入地下水,对As的富集有一定贡献;负载As的铁氧化物还原性溶解和沉积物中的As(V)还原性解吸附是地下水中As富集的主要原因;强还原环境中,硫酸盐还原作用形成的硫代砷可能会促使As在地下水中高度富集。In arid inland basins,high arsenic(As)groundwater threatens local drinking water safety,and its formation mechanism is still unclear.In this study,the groundwater in the Western Hetao Plain was studied,and the content of redox sensitive elements such as As and the isotope composition of hydrogen and oxygen(δD andδ^(18) O)were analyzed.The results showed that the concentration of As in groundwater varied from 1.5 to 155μg/L(average 36.7μg/L),and more than half of the samples exceed 10μg/L,mainly distributed in the central shallow aquifer.The correlation between hydrogen and oxygen isotopic compositions and ion concentrations indicated that although evaporation process enriched Na+and Cl-in groundwater,it has no significant effect on As enrichment,but the alkaline environment contributed to As desorption into groundwater.Reductive dissolution of As-bearing iron oxides and reductive desorption of As(V)from sediments were the main reasons of As enrichment in groundwater.The formation of thioarsenic by sulfate reduction in the strongly reducing environment might promote the extremely high concentration of As in groundwater.

关 键 词：河套平原 地下水 砷(As) 氧化还原环境 

分 类 号：P641[天文地球—地质矿产勘探]