Arsenic speciation in aquifer sediment under varying groundwater regime and redox conditions at Jianghan Plain of Central China
Arsenic speciation in aquifer sediment under varying groundwater regime and redox conditions at Jianghan Plain of Central China
复制标题
华中江汉平原不同地下水状况和氧化还原条件下含水层沉积物中的砷形态
DOI：
10.1016/j.scitotenv.2017.07.011
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发表时间：
2017-12-31
影响因子：
9.8
通讯作者：
Dong, Chuangju
中科院分区：
文献类型：
--
作者：
Duan, Yanhua;Gan, Yiqun;Dong, Chuangju
摘要在长江中下游江汉平原长期饮用高砷地下水，影响了约77.3万人的健康，通过野外监测点4个钻孔采集100余份沉积物样品进行分析，初步确定了浅层沉积物中砷的分布和形态。结果表明，沉积物As浓度普遍与岩性条件有关，细颗粒沉积物中As浓度较高，特别是粘土下的粉质砂层或粉质粘土层中。沉积物中高As浓度主要集中在3个不同的深度范围：35 m。地下水状态和氧化还原条件对沉积物的形成起着重要的控制作用。近地表沉积物中以砷酸盐（86%）为主。随着氧化还原转变为还原性，亚砷酸盐（64%）成为下伏粘土层和粉质粘土层的优势种。而在靠近非承压含水层和承压含水层边界的粉砂含水层中，由于氧化还原电位升高，砷酸盐（85%）再次成为优势种。在深中~粗砂含水层（bb0 ~ 35m）中，硫化物为主要砷种（49% ~ 63%）。沉积物As的形态和反应性强烈地控制着地下水As的空间分布，而地下水As浓度和形态的季节变化影响着沉积物As的含量和形态。(C) 2017 Elsevier B.V.版权所有
At Jianghan Plain of central Yangtze basins where the health of >73, 000 people has been affected by long term intake of high arsenic groundwater, over 100 sediment samples from four boreholes at the field monitoring sites were collected and analyzed to delineate the distribution and speciation of As in the shallow aquifer sediment. Results showed that sediment As concentration is generally dependent on the lithological conditions, with the higher As concentration present in fine particle sediment, especially in the silty sand layers underlying clay or silty clay layers. High As concentration in the sediment mainly occurred in three different depth ranges: 35 m. Both the groundwater regime and redox conditions played important roles in controlling sediment As speciation. Arsenate (86%) was the dominated As species in the near surface sediment. As the redox turned to be reducing, arsenite (64%) became the dominant species in the underlying clay and silty clay layers. But in the silty sand aquifer near the boundary of unconfined aquifer and confined aquifer, arsenate (85%) became the dominant species again as results of redox potential elevation. In the deep medium to coarse sand aquifers (>35m deep), As-sulfides (49%-63%) were the main species of As. The speciation and reactivity of sediment As strongly controlled the spatial distribution of groundwater As concentration, while seasonal variation in groundwater As concentration and speciation affected the content and speciation of sediment As. (C) 2017 Elsevier B.V. All rights reserved.