Sources and migration path of chemical compositions in a karst groundwater system during rainfall events  

Sources andSources and migration path of chemical compositions in a karst groundwater system during rainfall events

作　　者：YANG PingHeng YUAN DaoXian YE XuChun XIE ShiYou CHEN XueBin LIU ZiQi 

机构地区：[1]School of Geographical Sciences, Key Laboratory of Eco-environments in Three Gorges Reservoir, Ministry of Education, Southwest University [2]The Karst Dynamics Laboratory, Ministry of Land and Resources, Institute of Karst Geology, Chinese Academy of Geological Sciences

出　　处：《Chinese Science Bulletin》2013年第20期2488-2496,共9页

基　　金：supported by the National Natural Science Foundation of China (41103068 and 41072192);the Fundamental Research Funds for the Central Universities (XDJK2012B005);the National Key Technology R&D Program of China (2011BAC09B01 and 2006BAC01A16);the 2011 Scientific and Technical Program of the Land and Resource and Housing Management Bureau of Chongqing;the Project Supported by Karst Dynamics Laboratory, MLR and GZAR (KDL2012-08);the Natural Science Foundation of Chongqing (CSTC2010BC7004 and CSTC2009BA0002)

摘　　要：Physical and chemical dynamics at Jiangjia Spring (JJS), the outlet of the Qingmuguan karst groundwater system in Chongqing, were monitored in situ during rainfall events to acquire a series of high-resolution data. Principal component analysis (PCA) was employed to identify the sources of chemical compositions in the karst groundwater. The coefficients of variations (CVs) of the physical and chemical data of JJS were utilized to interpret the migration path of the chemical compositions. The results showed that water-rock interactions, agricultural activities, and soil erosion were the main sources of the groundwater chemical compositions. Ions of potassium, sodium, nitrate, chloride and phosphate from agricultural activities together with ions of calcium, magnesium, strontium and bicarbonate derived from carbonate dissolution appear to be stored and regulated by the karst unsaturated zone in features such as fissures, pores and solution cracks. The concentrations of the ions remained relatively stable and they showed low CVs owing to their migration by diffuse flow to recharge the underground river. In contrast, concentrations of ions such as total iron, total manganese and aluminum from soil erosion were unstable and showed high CVs owing to their migration by overland flow to recharge the underground river directly via sinkholes. During heavy rainfall events, the nutrients from agricultural activities and sediment from soil erosion could quickly impair the aquatic ecosystem and pose serious threats to water quality. Therefore, it is necessary to reinforce management of the ecological system for better control of the influx of mass nutrients into the karst aquifer system.Physical and chemical dynamics at Jiangjia Spring （JJS）, the outlet of the Qingmuguan karst groundwater system in Chongqing, were monitored in situ during rainfall events to acquire a series of high-resolution data. Principal component analysis （PCA） was employed to identify the sources of chemical compositions in the karst groundwater. The coefficients of variations （CVs） of the physical and chemical data of JJS were utilized to interpret the migration path of the chemical compositions. The results showed that water-rock interactions, agricultural activities, and soil erosion were the main sources of the groundwater chemical compositions. Ions of potassium, sodium, nitrate, chloride and phosphate from agricultural activities together with ions of calcium, magnesium, strontium and bicarbonate derived from carbonate dissolution appear to be stored and regulated by the karst unsaturated zone in features such as fissures, pores and solution cracks. The concentrations of the ions remained relatively stable and they showed low CVs owing to their migration by diffuse flow to recharge the underground river. In contrast, concentrations of ions such as total iron, total manganese and aluminum from soil erosion were unstable and showed high CVs owing to their migration by overland flow to recharge the underground river directly via sinkholes. During heavy rainfall events, the nutrients from agricultural activities and sediment from soil erosion could quickly impair the aquatic ecosystem and pose serious threats to water quality. Therefore, it is necessary to reinforce management of the ecological system for better control of the influx of mass nutrients into the karst aquifer system.

关 键 词：地下水系统 水化学成分 迁移路径 事件 岩溶 降雨 水生生态系统 化学组合物 

分 类 号：P641.3[天文地球—地质矿产勘探]