PCO2 variations of cave air and cave water in a subtropical cave, SW China

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Publication Date

June 2017

Abstract

Cave CO2 is an important part of the carbon cycle in a karst system. From 2008 to 2009 the partial pressure of CO2 (PCO2) of the cave air and cave water (cave stream and dripwater) in Xueyu Cave was studied. The PCO2 for cave air and cave water over two years showed that CO2 concentrations vary seasonally in all field sites, with higher CO2 concentrations in the wet season and lower concentrations in the dry season. These seasonal CO2 variations of cave air and cave water are attributed to seasonally variable soil CO2 production that is controlled by outside temperature fluctuations. Cave ventilation controls synchronous sharp variations of PCO2 from wet season to dry season or dry season to wet season in cave water and cave air. In the wet season, there were no obvious spatial differences of mean PCO2 in cave stream and cave air from upstream to downstream cave. Conversely, there were significant spatial differences of mean PCO2 in cave stream and cave air from upstream to downstream cave in the dry season because of cave ventilation. Mean dripwater PCO2 in D1 site where near cave entrance is much higher than that of the D2 and D3 sites where located in inner cave because D1 has a shorter flowpath from cave ceiling to soda-straw tip and lesser CO2 degassing along the flowpath. Further work in Xueyu Cave needs to clarify the quantitative relationship of CO2 cycle between cave air CO2 and cave water and focus on the influence of CO2 cycle on speleothem form.

Keywords

Pco2, Cave Stream, Cave Drip Water, Cave Air, Seasonal Variations, Spatial Variations

Document Type

Article

Notes

Carbonates and Evaporites, Vol. 33, no. 3 (2017-06-27).

Identifier

SFS0044374_00001

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