Characterising CO 2 carbon isotopic composition in a cave atmosphere at Havranická Cave , Malé Karpaty Mts . : A case study

This study provides the results of an investigation of the carbon isotopic composition in a CO2 cave atmosphere at Havranická Cave, Malé Karpaty Mts., Western Carpathians. The measured concentrations and δC values range between near-atmospheric (~ 612 ppmV and –7.38 ‰ PDB) values and depleted (~1039 ppmV and –13,5 ‰) values suggesting mixing of two contrasting CO2 sources. Other measured characteristics such as temperature, humidity and CO2 concentrations show trends related to depth, where temperature and humidity remain constant and the CO2 content increases with depth. We conclude that the carbon isotopic composition of cave air is a result of mixing of atmospheric and soil-derived CO2, degassed from dripwater. The contribution of carbon from limestone bedrock is possible, however, it cannot be confirmed with the current dataset.