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
The Ordovician karst groundwater in the Qiligou basin is an important water supply source. This groundwater has been seriously contaminated in recent years by Cfl4 from a pesticide plant located in the recharge area. ...The Ordovician karst groundwater in the Qiligou basin is an important water supply source. This groundwater has been seriously contaminated in recent years by Cfl4 from a pesticide plant located in the recharge area. The highest concentration of CCl4 in the groundwater is 3909.2μg/L. Large scale tracer experiments were carried out to study the conveying conduits for Cfl4 in the basin on May 1-6, 2005. Nontoxic, edible glucose was used as a tracer and it was detected by spectrophotometric techniques. Well area of the basin, was employed for injecting the tracer X-61, located near the pesticide plant in the southern recharge Ten wells widely located in the groundwater runoff area were used as observing and sampling wells. The results show that the migration of the pollutants is controlled by the water hydrodynamic field and by the development of karst conduits. The tracer did not enter the up-drainage wells, X-49 and X-47, near the injection point because the water levels at these wells are higher than at the injection point. The adjacent well X-62 is close to the injection site, but the tracer reached the well after eleven hours. Wells X-43, X-59, X-58, YY-1 and X-57, located in the syncline axis runoff area, are respectively 2.5, 3.5, 4.33, 4.38 and 5.44 kilometers from the in- jection site. The time for initial appearance of tracer was 4, 4, 2, 6 and 4 hours, respectively. The maximum runoff velocity （well X-58） is over two kilometers per hour, indicating that the karst conduits are well developed along the syncline basin axis. These conduits are the main conveying conduits for groundwater and Cfl4. Closer wells were not necessarily the first to receive tracer. This shows the inhomogeneity in karst development which causes complex runoff, and pollutant migration, patterns.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Project 40373044 supported by the National Natural Science Foundation of China
文摘The Ordovician karst groundwater in the Qiligou basin is an important water supply source. This groundwater has been seriously contaminated in recent years by Cfl4 from a pesticide plant located in the recharge area. The highest concentration of CCl4 in the groundwater is 3909.2μg/L. Large scale tracer experiments were carried out to study the conveying conduits for Cfl4 in the basin on May 1-6, 2005. Nontoxic, edible glucose was used as a tracer and it was detected by spectrophotometric techniques. Well area of the basin, was employed for injecting the tracer X-61, located near the pesticide plant in the southern recharge Ten wells widely located in the groundwater runoff area were used as observing and sampling wells. The results show that the migration of the pollutants is controlled by the water hydrodynamic field and by the development of karst conduits. The tracer did not enter the up-drainage wells, X-49 and X-47, near the injection point because the water levels at these wells are higher than at the injection point. The adjacent well X-62 is close to the injection site, but the tracer reached the well after eleven hours. Wells X-43, X-59, X-58, YY-1 and X-57, located in the syncline axis runoff area, are respectively 2.5, 3.5, 4.33, 4.38 and 5.44 kilometers from the in- jection site. The time for initial appearance of tracer was 4, 4, 2, 6 and 4 hours, respectively. The maximum runoff velocity （well X-58） is over two kilometers per hour, indicating that the karst conduits are well developed along the syncline basin axis. These conduits are the main conveying conduits for groundwater and Cfl4. Closer wells were not necessarily the first to receive tracer. This shows the inhomogeneity in karst development which causes complex runoff, and pollutant migration, patterns.
