The impact of damming on geochemical behavior of dissolved inorganic carbon in a karst river  

作　　者：Xi Peng Cong-Qiang Liu Baoli Wang Yan-Chuang Zhao 

机构地区：[1]State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences [2]College of Earth Science, University of Chinese Academy of Sciences

出　　处：《Chinese Science Bulletin》2014年第19期2348-2355,共8页

基　　金：supported by the National Basic Research Program of China (2013CB956703);the National Natural Science Foundation of China (41021062)

摘　　要：To determine the impact of damming on the geochemical behavior of dissolved inorganic carbon(DIC)in the Wujiang River basin,field measurements and samples were collected semimonthly for a year.The surface waters of the reservoirs contained concentrations of chlorophyll a up to 5.6 times higher than the upstream river.Compared with the entering waters,the contributions of HCO3-and dissolved CO2to DIC decreased,and the contribution of CO32-to DIC and the carbon isotopic composition of DIC(d13CDIC)increased in the surface waters of the reservoirs,while in the waters released,the DIC species showed reverse geochemical behaviors.The d13CDICranged from-10.2%to 2.5%,indicating that significant contributions were from carbonate weathering,photosynthesis,and respiration.After the damming of a river,the bioactivity of phytoplankton was enhanced,and this affected the geochemistry of DIC compared to an unimpacted river and d13CDICcan be used to discern these changes.High-frequency monitoring of river-reservoir systems is necessary to evaluate the efflux of CO2and provide a better understanding of the carbon sinks and sources in the impounded river.To determine the impact of damming on the geochemical behavior of dissolved inorganic carbon （DIC） in the Wujiang River basin, field measurements and samples were collected semimonthly for a year. The surface waters of the reservoirs contained concentrations of chlo- rophyll a up to 5.6 times higher than the upstream river. Compared with the entering waters, the contributions of HCO3- and dissolved CO2 to DIC decreased, and the contribution of CO32- to DIC and the carbon isotopic composition of DIC （δ13CDIc） increased in the surface waters of the reservoirs, while in the waters released, the DIC species showed reverse geochemical behaviors. The δ13CDIc ranged from -10.2 %o to 2.5 %0, indicating that significant contributions were from carbonate weathering, photosynthesis, and respiration. After the damming of a river, the bioactivity of phytoplankton was enhanced, and this affected the geochemistry of DIC compared to an unimpacted river and δ13CDIC can be used to discern these changes. High-frequency monitoring of river-reservoir systems is necessary to evaluate the efflux of CO2 and provide a better understanding of the carbon sinks and sources in the impounded river.

关 键 词：地球化学行为 溶解无机碳 河流 筑坝 喀斯特 碳同位素组成 水库系统 DIC 

分 类 号：P342[天文地球—水文科学]