Liu Cong-Qiang, Lang Yun-Chao, Satake Hiroshi, Wu Jiahong, Li Si-Liang
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China.
Environ Sci Technol. 2008 Aug 1;42(15):5421-7. doi: 10.1021/es800380w.
Because of active exchange between surface and groundwater of a karstic hydrological system, the groundwater of Guiyang, the capital city of Guizhou Province, southwest China, has been seriously polluted by anthropogenic inputs of NO3-, SO4(2-), Cl-, and Na+. In this work, delta37Cl of chloride and delta34S variations of sulfate in the karstic surface/groundwater system were studied, with a main focus to identify contaminant sources, including their origins. The surface, ground, rain, and sewage water studied showed variable delta37Cl and delta34S values, in the range of -4.1 to +2.0 per thousand, and -20.4 to +20.9 per thousand for delta37Cl and delta34S (SO4(2-)), respectively. The rainwater samples yielded the lowest delta37Cl values among those observed to date for aerosols and rainwater. Chloride in the Guiyang area rain waters emanated from anthropogenic sources rather than being of marine origin, probably derived from HCl (g) emitted by coal combustion. By plotting 1/SO4(2-) vs delta34S and 1/Cl- vs delta37Cl, respectively, we were able to identify some clusters of data, which were assigned as atmospheric deposition (acid rain component), discharge from municipal sewage, paleo-brine components in clastic sedimentary rocks, dissolution of gypsum mainly in dolomite, oxidation of sulfide minerals in coal-containing clastic rocks, and possibly degradation of chlorine-containing organic matter. We conclude that human activities give a significant input of sulfate and chloride ions, as well as other contaminants, into the studied groundwater system through enhanced atmospheric deposition and municipal sewage, and that multiple isotopic tracers constitute a powerful tool to ascertain geochemical characteristics and origin of complex contaminants in groundwater.
由于岩溶水文系统中地表水与地下水的活跃交换，中国西南部贵州省省会贵阳市的地下水受到人为输入的NO3-、SO4(2-)、Cl-和Na+的严重污染。在这项工作中，研究了岩溶地表水/地下水系统中氯离子的δ37Cl和硫酸根的δ34S变化，主要目的是确定污染物来源，包括其起源。所研究的地表水、地下水、雨水和污水的δ37Cl和δ34S值各不相同，δ37Cl的范围为-4.1‰至+2.0‰，δ34S（SO4(2-)）的范围为-20.4‰至+20.9‰。雨水样本的δ37Cl值是迄今为止观测到的气溶胶和雨水中最低的。贵阳地区雨水中的氯离子源自人为源而非海洋源，可能来自煤炭燃烧排放的HCl（气体）。通过分别绘制1/SO4(2-)对δ34S和1/Cl-对δ37Cl的关系图，我们能够识别出一些数据聚类，它们分别被确定为大气沉降（酸雨成分）、城市污水排放、碎屑沉积岩中的古卤水成分、主要在白云岩中石膏的溶解、含煤碎屑岩中硫化物矿物的氧化以及可能含氯有机物的降解。我们得出结论，人类活动通过增强大气沉降和城市污水向所研究的地下水系统大量输入硫酸根和氯离子以及其他污染物，并且多种同位素示踪剂是确定地下水中复杂污染物地球化学特征和来源的有力工具。
