Concentration and stable carbon isotopic composition of CO₂ in cave air of Postojnska jama, Slovenia

Authors

Magda Mandić, Physics Department, University of Rijeka, Rijeka, CroatiaFollow
Andrej Mihevc, Karst Research Institute, Postojna, SloveniaFollow
Albrecht Leis, Joanneum Research, RESOURCES - Institute for Water, Energy and Sustainability, Graz, AustriaFollow
Ines Krajcar Bronić, Rudjer Boskovic Institute, Zagreb, CroatiaFollow

Abstract

Partial pressure of CO₂ (pCO₂) and its isotopic composition (δ¹³C_airCO2) were measured in Postojnska jama, Slovenia, at 10 locations inside the cave and outside the cave during a one-year period. At all interior locations the pCO₂ was higher and δ¹³C_airCO2 lower than in the outside atmosphere. Strong seasonal fluctuations in both parameters were observed at locations deeper in the cave, which are isolated from the cave air circulation. By using a binary mixing model of two sources of CO₂, one of them being the atmospheric CO₂, we show that the excess of CO₂ in the cave air has a δ¹³C value of -23.3 ± 0.7 ‰, in reasonable agreement with the previously measured soil-CO₂ δ¹³C values. The stable isotope data suggest that soil CO₂ is brought to the cave by drip water.

DOI

http://dx.doi.org/10.5038/1827-806X.42.3.11

Recommended Citation

Mandić, Magda; Andrej Mihevc; Albrecht Leis; and Ines Krajcar Bronić. 2013. Concentration and stable carbon isotopic composition of CO₂ in cave air of Postojnska jama, Slovenia. International Journal of Speleology, 42: 279-287.
Available at: https://digitalcommons.usf.edu/ijs/vol42/iss3/11