Geochemical evolution of groundwater in carbonate aquifers in Taiyuan, northern China
Geochemical evolution of groundwater in carbonate aquifers in Taiyuan, northern China
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太原碳酸盐岩含水层地下水地球化学演化
DOI：
10.1016/j.apgeochem.2011.02.008
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发表时间：
2011-05-01
影响因子：
3.4
通讯作者：
Prommer, Henning
中科院分区：
文献类型：
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作者：
Ma, Rui;Wang, Yanxin;Prommer, Henning
为了更好地了解控制该地区碳酸盐含水层地下水质量演化的地球化学过程，对中国北方太原39个冷、热岩溶地下水样本进行了采集和分析。将该区岩溶地下水系统划分为3个地质特征明显的子系统，即西山岩溶地下水子系统（XMK）、东山岩溶地下水子系统（DMK）和北山岩溶地下水子系统（BMK）。岩溶地下水水化学性质由回灌区向冷水排放区发展，再向热水排放区发展。在XMK和DMK，地下水的水化学类型从补给流区HCO(3)- ca中心点Mg，到冷水排放区HCO(3)中心点SO(4)- ca中心点Mg/SO(4)中心点HCO(3)- ca中心点Mg，再到热水排放区SO(4)- ca中心点Mg。而在BMK中，水的类型从HCO(3)-Ca中心点Mg转变为HCO(3)-SO(4)-Ca中心点Mg，从补给区到排放区，TDS和温度几乎保持不变。随着地下水温度的升高，Sr、Si、Fe、F（-）和一些微量元素（Al、B、Li、Mn、Mo、Co、Ni）的浓度增加。3个岩溶地下水子系统发生不同的水文地球化学过程。在XMK和DMK中，地下水的地球化学演化受碳酸盐溶蚀/沉淀、石膏溶蚀和脱白云作用共同控制，而BMK中只发生方解石和白云石溶蚀/沉淀，不发生脱白云作用。利用岩溶地下水水文地球化学数据，分别构建岩溶地下水3个不同子系统的地球化学反应模型。模拟结果证实，脱白云作用是控制XMK和DMK水化学变化的主要过程。在热地下水中，萤石、菱铁矿和锶矿的溶解速率超过冷岩溶地下水系统，这可以解释在热地下水中发现较高的F（-）、Fe和Sr（2+）浓度。(C) 2011 Elsevier Ltd.版权所有。
Thirty-nine samples of both cold and thermal karst groundwater from Taiyuan, northern China were collected and analyzed with the aim of developing a better understanding of the geochemical processes that control the groundwater quality evolution in the region's carbonate aquifers. The region's karst groundwater system was divided into three geologically distinct sub-systems, namely, the Xishan Mountain karst groundwater subsystem (XMK), the Dongshan Mountain karst groundwater subsystem (DMK) and the Beishan Mountain karst groundwater subsystem (BMK). Hydrochemical properties of the karst groundwaters evolve from the recharge zones towards the cold water discharge zones and further towards the thermal water discharge zones. In the XMK and the DMK, the hydrochemical type of the groundwater evolves from HCO(3)-Ca center dot Mg in the recharge - flow-through zone, to HCO(3)center dot SO(4)-Ca center dot Mg/SO(4)center dot HCO(3)-Ca center dot Mg in the cold water discharge zone, and further to SO(4)-Ca center dot Mg in the thermal water discharge zone. By contrast, the water type changes from HCO(3)-Ca center dot Mg to HCO(3)-SO(4)-Ca center dot Mg in the BMK, with almost invariable TDS and temperatures all along from the recharge to the discharge zone. The concentrations of Sr, Si, Fe, F(-) and of some trace elements (Al, B, Li, Mn, Mo, Co, Ni) increase as groundwater temperature increases. Different hydrogeochemical processes occur in the three karst groundwater sub-systems. In the XMK and the DMK, the geochemical evolution of the groundwater is jointly controlled by carbonate dissolution/precipitation, gypsum dissolution and dedolomitization, while only calcite and dolomite dissolution/precipitation occurs in the BMK without dedolomitization. The hydrogeochemical data of the karst groundwaters were used to construct individual geochemical reaction models for each of the three different karst groundwater sub-systems. The modeling results confirm that dedolomization is the major process controlling hydrochemical changes in the XMK and the DMK. In the thermal groundwaters, the dissolution rates of fluorite, siderite and strontianite were found to exceed those of the cold karst groundwater systems, which can explain the higher concentrations of F(-), Fe and Sr(2+) that are found in these waters. (C) 2011 Elsevier Ltd. All rights reserved.