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. P...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.展开更多
High-frequency samples have been collected at Jiangjia Spring, the outlet of Qingmuguan underground river system (QURS) in Chongqing in late April, 2008. The variations of hydrogeochemical compositions are found respo...High-frequency samples have been collected at Jiangjia Spring, the outlet of Qingmuguan underground river system (QURS) in Chongqing in late April, 2008. The variations of hydrogeochemical compositions are found responding rapidly to storm events. Principal component analysis (PCA) of the 20 variables is employed to interpret the relationships with specific processes that control the groundwater hydrogeochemical formations. Through PCA, 84.961% of the total amount information is extracted to indicate the formations of groundwater hydrogeochemical features in QURS during storm events. The first component separates the soil erosion (i.e., increases in turbidity and concentrations of Al3+, TFe, TMn, Ba2+ and NO2?), and dilution effect (i.e., decreases in specific conductance and concentrations of HCO3?, Ca2+ and Sr2+), accounting for 41.495% of the variability in the data. The second component indicates residual fertilizers and duck’s waste from farmlands (i.e., increases in specific conductance and concentrations of Na+, NO3-, PO43-,K+and Cl-), contributing to 37.449%. The dissolution of dolomite and dolomitic limestone makes up 6.017%. During the first rainfall event, the groundwater quality is mainly affected by residual fertilizers and duck’s waste from farmlands, whereas in the second rainfall event, it is mainly affected by increased turbidity and ionic concentrations caused by soil erosion.展开更多
基金supported by the National Natural Science Foundation of China (41103068 and 41072192)the Fundamental Research Funds for the Central Universities (XDJK2012B005)+3 种基金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 Chongqingthe Project Supported by Karst Dynamics Laboratory, MLR and GZAR (KDL2012-08)the Natural Science Foundation of Chongqing (CSTC2010BC7004 and CSTC2009BA0002)
文摘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.
基金supported by the National Key Technologies R & D Program of China (Grant Nos.2006BAC01A09 and 2006BAC01A16)National Natural Science Foundation of China (Grant No. 40672165)+2 种基金Natural Science Foundation of Chongqing (Grant Nos. CSTC2007BC7001 and CSTC2009BA0002)Open Foundation of Chongqing Key Laboratory of The Three Gorges Storehouse District Forest Ecology Protects and Restores (Grant No.CKL200802)Fund for Graduate Student of Technologic Innovation in Southwest University (Grant Nos. ky2008001 and kb2009004)
文摘High-frequency samples have been collected at Jiangjia Spring, the outlet of Qingmuguan underground river system (QURS) in Chongqing in late April, 2008. The variations of hydrogeochemical compositions are found responding rapidly to storm events. Principal component analysis (PCA) of the 20 variables is employed to interpret the relationships with specific processes that control the groundwater hydrogeochemical formations. Through PCA, 84.961% of the total amount information is extracted to indicate the formations of groundwater hydrogeochemical features in QURS during storm events. The first component separates the soil erosion (i.e., increases in turbidity and concentrations of Al3+, TFe, TMn, Ba2+ and NO2?), and dilution effect (i.e., decreases in specific conductance and concentrations of HCO3?, Ca2+ and Sr2+), accounting for 41.495% of the variability in the data. The second component indicates residual fertilizers and duck’s waste from farmlands (i.e., increases in specific conductance and concentrations of Na+, NO3-, PO43-,K+and Cl-), contributing to 37.449%. The dissolution of dolomite and dolomitic limestone makes up 6.017%. During the first rainfall event, the groundwater quality is mainly affected by residual fertilizers and duck’s waste from farmlands, whereas in the second rainfall event, it is mainly affected by increased turbidity and ionic concentrations caused by soil erosion.
