Hydrochemical evolution of groundwater in a riparian zone affected by acid mine drainage (AMD), South China: the role of river-groundwater interactions and groundwater residence time
Hydrochemical evolution of groundwater in a riparian zone affected by acid mine drainage (AMD), South China: the role of river-groundwater interactions and groundwater residence time
复制标题
华南酸性矿山排水（AMD）影响的河岸带地下水水化学演化：河流-地下水相互作用和地下水停留时间的作用
DOI：
10.1007/s12665-018-7977-2
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发表时间：
2018
影响因子：
2.8
通讯作者：
Chen Qian
中科院分区：
文献类型：
--
作者：
Wen Jing;Tang Changyuan;Cao Yingjie;Li Xing;Chen Qian
在中国南方AMD地区上坝村附近的河岸带进行了调查，以确定河流与地下水相互作用和地下水停留时间对环境质量和地下水地球化学演化的影响。基于达西定律和离子质量平衡以及同位素示踪方法，结果表明研究区河岸带AMD污染河水与地下水之间存在活跃的相互作用。研究区西北部地区地下水补给以河水为主，而研究区东南部地区地下水常年排入河流。端元混合分析量化了河水对地下水的贡献沿着流路逐渐从35.9%下降到可以忽略不计的水平。计算出的主要离子混合浓度表明水岩反应是对地下水质量最重要的影响。 Ca2++ Mg2+和HCO3−比率的大范围变化以及地下水类型从Ca2+–SO42−型到以Ca2+–HCO3−型为主的化学成分的变化表明沿地下水流路主要水岩反应过程从H2SO4(AMD)的影响转变为CO2(土壤呼吸)的影响。此外，SO42−和HCO3−浓度的动力学解释表明，它们动力学的重叠时间触发了水化学演化和主要风化剂的变化。这个过程可能需要大约 8 年，当稳定的污染源进入含水层时，这个动力时间将会持续下去。
Investigations were undertaken in the riparian zone near Shangba village, an AMD area, in southern China to determine the effects that river–groundwater interactions and groundwater residence time have had on environmental quality and geochemical evolution of groundwater. Based on the Darcy’s law and ionic mass balances as well as the method of isotopic tracer, the results showed that there were active interactions between AMD-contaminated river water and groundwater in the riparian zone in the study area. River water was found to be the main source of groundwater recharge in the northwestern part of the study area, whereas groundwater was found to be discharging into the river in the southeastern part of the study area throughout the year. End-member mixing analysis quantified that the contributions of river water to groundwater decreased gradually from 35.9% to negligible levels along the flow path. The calculated mixing concentrations of major ions indicated that water–rock reactions were the most important influence on groundwater quality. The wide range of Ca2++ Mg2+and HCO3−ratios and the change of groundwater type from Ca2+–SO42−type to a chemical composition dominated by Ca2+–HCO3−type indicated a change of the major water–rock reaction process from the influence of H2SO4(AMD) to that of CO2(soil respiration) along a groundwater flow path. Furthermore, the kinetics interpretation of SO42−and HCO3−concentrations suggested that the overlapping time of their kinetics triggered the hydrochemical evolution and the change of major weathering agent. This process might take approximately 8 years and this kinetic time will be continued when a steady source of contamination enter the aquifer.