Ecosystem-driven karst carbon cycle and carbon sink effects |
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| Authors: | Zhang Cheng Xiao Qiong Wu Ze-yan Martin Knez |
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| Affiliation: | 1.Karst Dynamics Key Laboratory of Ministry of Natural Resources/Guangxi Zhuang Autonomous Region, Institute of Karst Geology, Chinese Academy of Geological Sciences/International Research Center on Karst Under the Auspices of UNESCO, Guilin 541004, Guangxi, China2.Karst Research Institute, Slovenian Academy of Sciences and Arts, Postonja, SI-6230, Slovenia |
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| Abstract: | It is recognized that karst processes are actively involved in the current global carbon cycle based on twenty years research, and the carbon sink occurred in karst processes is possibly an important part of “missing sink” in global carbon cycle. In this paper, an overview is given on karst carbon cycle research, and influence factors, formed carbon pools (background carbon sink) and sink increase potentials of current karst carbon cycle are analyzed. Carbonate weathering could contribute to the imbalance item (BIM) and land use change item (ELUC) in the global carbon cycle model, owing to its uptake of both atmospheric CO2 (carbon sink effect) and CO2 produced by soil respiration (carbon source reduction effect). Karst carbon sink includes inorganic carbon sink resulted from hydrogeochemical process and organic carbon sink generated by aquatic photosynthetic DIC conversion, forming relatively stable river (reservoir) water body or sediment carbon sink. The sizes of both sinks are controlled by terrestrial ecosystems and aquatic ecosystems, respectively. Desertification rehabilitation and carbon sequestration by aquatic plants are two effective ways to increase the carbon sink in karst area. It is estimated that the rate of carbon sink is at least 381 000 t CO2/a with vegetation restoration and afforestation in southwest China karst area, while the annual organic carbon sink generated by aquatic photosynthesis is about 84 200 t C in the Pearl River Basin. The development of a soil CO2 based model for assessment of regional dissolution intensity will help to improve the estimation accuracy of carbon sink increase and potential, thus provide a more clear and efficient karst sink increase scheme and pathway to achieve the goals of “double carbon”. With the deep investigation on karst carbon cycle, mechanism and carbon sink effect, and the improvement of watershed carbon sink measurement methods and regional sink increase evaluation approaches. Karst carbon sink is expected to be included in the list of atmospheric CO2 sources/sinks of the global carbon budget in the near future. |
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| Keywords: | Karst carbon sink Ecosystem Sink-increase way Carbon pool Rock desertification rehabilitation Aquatic photosynthetic carbon sequestration |
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