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

Zhongfa Zhou (), Jie Kong, Fuqiang Zhang, Yan Zou, Jiangting Xie and Chaocheng Wen
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Zhongfa Zhou: School of Karst Science, Guizhou Normal University, Guiyang 550001, China
Jie Kong: School of Karst Science, Guizhou Normal University, Guiyang 550001, China
Fuqiang Zhang: School of Karst Science, Guizhou Normal University, Guiyang 550001, China
Yan Zou: School of Karst Science, Guizhou Normal University, Guiyang 550001, China
Jiangting Xie: School of Karst Science, Guizhou Normal University, Guiyang 550001, China
Chaocheng Wen: School of Karst Science, Guizhou Normal University, Guiyang 550001, China

Land, 2023, vol. 12, issue 2, 1-16

Abstract: The hydrochemical analysis method was used to reveal the sources and spatiotemporal variations of carbon and nitrogen elements in the Pingzhai Reservoir, and the C–N coupling cycle and its influence on the karst carbon sink are discussed. The results show the following: (1) The hydrochemical type of the study area is HCO 3 -Ca. (2) From the river to the reservoir and then to the reservoir outlet, the values of HCO 3 − and δ 13 C DIC showed an opposite trend. The values of NO 3 − , δ 15 N-NO 3 − , and δ 18 O-NO 3 − were different in each stage of the river. (3) HCO 3 − mainly comes from the weathering of carbonate rocks and the oxidative decomposition of organic matter. Nitrate mainly comes from chemical fertilizers, soil organic nitrogen, sewage, and livestock manure. (4) The average proportion of HCO 3 − produced by HNO 3 dissolving carbonate rock is 8.38%, but this part does not constitute a carbon sink. Compared with rivers, the proportion of HCO 3 − and (Ca 2+ + Mg 2+ ) produced by HNO 3 dissolving carbonate rock in reservoir water is relatively large. The input of nitrate not only pollutes the water body with NO 3 − but also changes the carbon source/sink pattern of the water–rock interaction.

Keywords: karst carbon sink; carbon and nitrogen sources; dissolved inorganic carbon isotopes; nitrogen and oxygen isotopes; karst area reservoir (search for similar items in EconPapers)
JEL-codes: Q15 Q2 Q24 Q28 Q5 R14 R52 (search for similar items in EconPapers)
Date: 2023
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