Hydrogeochemistry and arsenic contamination of groundwater in the Jianghan Plain, central China
Hydrogeochemistry and arsenic contamination of groundwater in the Jianghan Plain, central China
复制标题
江汉平原地下水水文地球化学与砷污染
DOI：
10.1016/j.gexplo.2013.12.013
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发表时间：
2014-03-01
影响因子：
3.9
通讯作者：
Ding, Xufeng
中科院分区：
文献类型：
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作者：
Gan, Yiqun;Wang, Yanxin;Ding, Xufeng
我国西北地区地下水砷含量较高，但在中部平原地区地下水砷含量的研究还未见报道。在长江和汉江之间的江汉平原上采集了186个地下水样品。主要成分，微量元素，溶解有机碳（DOC），稳定的氢和氧同位素组成进行了分析，表征地下水化学和评估的因素控制砷的浓度和分布在平原。结果表明，该区地下水主要为HCO 3-CaMg型，pH值偏中性，电导率为中-高。负Eh和高浓度的DOC清楚地表明强烈的还原条件下，在地下水含水层丰富的有机质。H/O稳定同位素特征表明，研究区地下水主要由局部降水补给，存在缓慢的蒸发作用。在沿着10 ~ 45 m深的威尔斯井中发现了高砷地下水。约87%的地下水样品中As浓度超过WHO推荐值10 μ g/L，高达2330 μ g/L。地下水中溶解态Fe（最大值为23 mg/L）、Mn（最大值为5 mg/L）和P（最大值为4 mg/L）的浓度也较高。在威尔斯的水井中，89%和98%的水井中的铁和锰分别超过了WHO的指导值。江汉平原沉积物中总砷含量为11 ~ 108 mg/kg，远高于全球平均水平。沉积物中Fe（Fe_2O_3 4-9%）和Mn（504-1064 mg/kg）含量较高，这与江汉平原沉积物中Fe和Mn的氧化物/氢氧化物是主要的含砷矿物和地下水中As的主要来源相一致。As释放的主要潜在机制是Fe和Mn氧化物/氢氧化物在还原条件下的还原溶解，而有机物的微生物降解也可能促进砷释放到地下水中。其他阴离子的竞争效应也可能是重要的因素，因为许多地下水样品中DOC、HCO 3-和溶解态P的浓度都很高。(C)2014爱思唯尔有限公司版权所有。
Although high arsenic groundwater has been reported in the northwest of China, no data describing groundwater arsenic in the river plains of central China have been published to date. In this study, 186 groundwater samples were collected from the Jianghan Plain between the Yangtze and Han rivers. Major constituents, trace elements, dissolved organic carbon (DOC), and stable hydrogen and oxygen isotopic compositions were analyzed to characterize groundwater chemistry and evaluate the factors controlling arsenic concentration and distribution in the plain. The results show that the groundwater is mainly HCO3-CaMg type with circum-neutral pH and moderate to high electrical conductivity. Negative Eh and high concentrations of DOC clearly indicate strongly reducing conditions with abundant organic matter in the groundwater aquifers. The characteristics of H/O stable isotopes demonstrate that the groundwater in the study area is recharged by local precipitation and there is a slow evaporation effect. Groundwater with high arsenic was found in wells at depths of 10 to 45 m along rivers. About 87% of the groundwater samples had As concentrations exceeding the WHO recommended value of 10 mu g/L, up to 2330 mu g/L. High concentrations of dissolved Fe (maximum value, 23 mg/L), Mn (maximum value, 5 mg/L) and P (maximum value, 4 mg/L) were also observed in groundwater. Among the wells, 89% and 98% exceeded the WHO guideline for Fe and Mn, respectively. The concentrations of total As measured in sediments from the Jianghan Plain were much higher than the global average, ranging from 11 to 108 mg/kg. All of the sediments had high Fe (Fe2O3 4-9%) and Mn (504-1064 mg/kg) levels, which is consistent with Fe and Mn oxides/hydroxides considered to be the dominant minerals containing As in sediments and the main sources for As in groundwater of the Jianghan Plain. The main potential mechanism for the release of As is the reductive dissolution of Fe and Mn oxides/hydroxides under reducing conditions, while microbial degradation of organic matter may also facilitate the release of arsenic into groundwater. The competitive effects Of other anions may also be important factors since the concentrations of DOC, HCO3- and dissolved P were high in many of the groundwater samples. (C) 2014 Elsevier B.V. All rights reserved.