Episodes 2022; 45(4): 431-444
Published online December 1, 2022
Copyright © International Union of Geological Sciences.
Liangxing Shi1,2, Zhongfa Zhou1,2*, Baoxiang Fan1,2, Lihui Yan1,2, Shengjun Ding1, Heng Zhang1,2, Jing Huang1
1School of Karst Science/Geography and Environmental Science, Guizhou Normal University, Guiyang 550001, China
2State Key Laboratory Base of Karst Mountain Ecology, Guiyang 550001, China
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CO2 is an important driving force in karstification. Studying the variation characteristics of CO2 in each zone of a karst cave system during different seasons might contribute to revealing its migration path and to further exploring CO2 sources in caves. To this end, we monitored the soil, cave drip water, and cave air CO2 in Mahuang Cave, SW China. We analyzed the vertical migration characteristics of CO2 based on the carbonic acid equilibrium system theory and the stable isotopes of carbon through statistical analysis. The results show the following: (1) There are obvious seasonal changes in CO2 in each zone of Mahuang Cave, generally indicating high rainy season and low dry season characteristics. (2) The CO2 in Mahuang Cave is mainly supplied by the soil, bedrock, and the external atmosphere. The rainy season has plentiful rainfall, and the CO2 in the cave is mainly derived from soil CO2. In the dry season, with lower temperature and little rain, cave CO2 is mainly attributed to the external atmosphere, brought by the ventilation effect, and carbon in the bedrock. (3) Carbonate precipitation in Mahuang Cave is dominant throughout the year. The seepage migration process and carbonate precipitation are controlled by the soil “CO2 effect” and drip water type.