Study on the Carbon and Nitrogen Isotope Characteristics and Sources and Their Influence on Carbon Sinks in Karst Reservoirs

The hydrochemical analysis method was used to reveal the sources and spatiotemporal variations of carbon nitrogen elements in Pingzhai Reservoir, C–N coupling cycle its influence on karst sink are discussed. results show following: (1) type study area is HCO3-Ca. (2) From river reservoir then outlet, values HCO3− δ13CDIC showed an opposite trend. NO3−, δ15N-NO3−, δ18O-NO3− were different each stage river. (3) mainly comes from weathering carbonate rocks oxidative decomposition organic matter. Nitrate chemical fertilizers, soil nitrogen, sewage, livestock manure. (4) average proportion produced by HNO3 dissolving rock 8.38%, but this part does not constitute a sink. Compared with rivers, (Ca2+ + Mg2+) water relatively large. input nitrate only pollutes body NO3− also changes source/sink pattern water–rock interaction.