Short-term CO₂(g) exchange between a shallow karstic cavity and the external atmosphere during summer: Role of the surface soil layer

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• 作者：S. Cuezva^a ; ^{scuezva@mncn.csic.es} ; A. Fernandez-Cortes^a ; D. Benavente^b ; P. Serrano-Ortiz^c ; A.S. Kowalski^d ; ^e ; S. Sanchez-Moral^a
• 关键词：Epikarst ; Ventilation ; Eddy covariance ; Soil porosity ; Evapotranspiration ; Global carbon cycle
• 刊名：Atmospheric Environment
• 出版年：2011
• 出版时间：March 2011
• 年：2011
• 卷：45
• 期：7
• 页码：1418-1427
• 全文大小：1417 K

文摘

This study tests the hypothesis that the degree of moisture in the soil pore system determines gas exchange processes (ventilation/charge) between the outer atmosphere and the karst-epikarst during the warm, dry period (summer). These processes explain “anomalous” CO₂ fluxes measured over this and other ecosystems. Emission of CO₂ by ventilation of cavities requires an open double membrane system (host rock and soil) through which air movement can take place (H₂O_vapour, CO₂, ²²²Rn, etc.). An experimental study on the behavior of the soil and host rock porous system under changing air humidity conditions, coupled with a broad analytical approach addressing CO₂ fluxes using the eddy-covariance technique and monitoring of the cave microclimate serves to define the suitable environmental conditions favoring air transfer between the cave atmosphere and exterior. This study shows the correlation between evapotranspiration, CO₂ emissions, and cave ventilation processes due to the daytime opening of the soil membrane. Thus, the role of the soil as a membrane/interface or transfer medium can be observed, and it is directly dependent on weather conditions (temperature, humidity, wind).