CO₂ and Temperature Variations During Peak Tourist Season in Lepe Jame (Postojna Cave, Slovenia)
DOI:
https://doi.org/10.3986/ac.v54i2.14931Keywords:
karst, cave climate, show cave, carbon dioxide, cave monitoringAbstract
We present and analyze measurements of CO₂ concentration and air temperature taken during the peak tourist season of 2017 in Lepe Jame, a poorly ventilated passage within Postojnska Jama, Slovenia. During the study, the passage was visited by between 5500 and 6500 visitors per day. Both parameters show pronounced diurnal fluctuations, primarily driven by visitor activity. As part of our campaign, we tested and confirmed the effectiveness of enhanced ventilation—achieved by opening the artificial tunnel connecting Postojnska Jama to Črna Jama—in preventing excessively high CO₂ concentrations. The measure is, however, questionable, as it affects the microclimate in Črna Jama. Although CO₂ concentration and temperature are correlated, notable differences emerge in the shapes of their respective rise and recession curves. Temperature increases more rapidly with the arrival of visitors, while it decreases more slowly after visiting hours compared to CO₂. This lag is attributed to thermal storage: heat from visitors is absorbed by the cave walls during the day and gradually released into the cave during the night.
Downloads
References
Covington, M. D., Perne, M., 2016. Consider a Cylindrical Cave: A Physicist’s View of Cave and Karst Science. Acta Carsologica ,44 (3). https://doi.org/10.3986/ac.v44i3.1925
Covington, M. D., Prelovšek, M., Gabrovšek, F., 2013. Influence of CO2 Dynamics on the Longitudinal Variation of Incision Rates in Soluble Bedrock Channels: Feedback Mechanisms. Geomorphology, 186: 85–95. https://doi.org/10.1016/j.geomorph.2012.12.025
European Union, 2024. Directive (EU) 2024/2881 of the European Parliament and of the Council of 23 October 2024 on Ambient Air Quality and Cleaner Air for Europe (Recast). http://data.europa.eu/eli/dir/2024/2881/oj/eng [Accessed 10 November 2025]
Field, M. S., 1999. A Lexicon Of Cave And Karst Terminology With Special Reference To Environmental Karst Hydrology (1999 Edition). U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Washington Office. https://cfpub.epa.gov/ncea/risk/era/recordisplay.cfm?deid=12468
Gabrovšek, F., 2023. How Do Caves Breathe: The Airflow Patterns in Karst Underground. PLOS ONE, 18 (4): e0283767. https://doi.org/10.1371/journal.pone.0283767
Gabrovšek, F., Grašič, B., Zlata Božnar m., Udén, M., Davies ., 2014. Karst Show Caves: How DTN Technology as Used in Space Assists Automatic Environmental Monitoring and Tourist Protection-Experiment in Postojna Cave. Natural Hazards and Earth System Sciences, 14 (2): 443–57. https://doi.org/10.5194/nhess-14-443-2014
Hardy, J. D., DuBois, E. F., 1937. Regulation of Heat Loss from the Human Body. Proceedings of the National Academy of Sciences, 23(12): 624–31. https://doi.org/10.1073/pnas.23.12.624
Kilpatrick, F. A., Cobb, E.D., 1985. Measurement of Discharge Using Tracers. U.S. In: Geological Survey Techniques of Water-Resources Investigations, book 3, chap. A16. US Geological Survey.
Küçükhüseyin, Ö., 2021. CO₂ Monitoring and Indoor Air Quality. The REHVA European HVAC Journal, 58 (1): 54–59.
Kukuljan, L., Gabrovšek, F., Covington, M.D., Johnston, V.E., 2021a. CO2 Dynamics and Heterogeneity in a Cave Atmosphere: Role of Ventilation Patterns and Airflow Pathways. Theoretical and Applied Climatology, 146 (1): 91–109. https://doi.org/10.1007/s00704-021-03722-w
Kukuljan, L., Gabrovšek, F., Johnston, V.E.,2021b. Low-Calcium Cave Dripwaters in a High CO2 Environment: Formation and Development of Corrosion Cups in Postojna Cave, Slovenia. Water, 13 (22): 3184. https://doi.org/10.3390/w13223184
LibreTexts,2025. Avogadro’s Hypothesis and Molar Volume. Chemistry LibreTexts. https://chem.libretexts.org/@go/page/53770 [Accessed 10 November 2025].
Lowther, S.D., Dimitroulopoulou, S., Foxall, K., 2021. Low Level Carbon Dioxide Indoors—A Pollution Indicator or a Pollutant? A Health-Based Perspective. Environments, 8 (11): 125. https://doi.org/10.3390/environments8110125
Luhmann, A. J., Covington, M. D., Myre, J. M. , Perne, M., Jones, S.W., Alexander, W.C., Saar, M.O., 2015. Thermal Damping and Retardation in Karst Conduits. Hydrology and Earth System Sciences, 19 (1): 137–57. https://doi.org/10.5194/hess-19-137-2015
Milanolo, S., Gabrovšek, F., 2009. Analysis of Carbon Dioxide Variations in the Atmosphere of Srednja Bijambarska Cave, Bosnia and Herzegovina. Boundary-Layer Meteorology, 131 (3): 479–93. https://doi.org/10.1007/s10546-009-9375-5
Mlakar, P., Grašič, B., Božnar, M.Z., Popović, D., Gabrovšek, F., 2020. Information System for Scientific Study of the Micrometeorology of Karst Caves – Case of Postojnska Jama Cave, Slovenija. Acta Carsologica, 49 (2–3). https://doi.org/10.3986/ac.v49i2-3.7540
OpenStax, LibreTexts, 2025. Heat Capacities of an Ideal Gas. https://phys.libretexts.org/@go/page/4362 [Accessed 10 November 2025].
Patel, H., Bhardwaj. A., 2025. Physiology, Respiratory Quotient. http://www.ncbi.nlm.nih.gov/books/NBK531494/ [Accessed 10 November 2025].
Römer, D., Halboth, F., Bollazzi, M., Roces, F., 2018. Underground Nest Building: The Effect of CO2 on Digging Rates, Soil Transport and Choice of a Digging Site in Leaf-Cutting Ants. Insectes Sociaux, 65 (2): 305–13. https://doi.org/10.1007/s00040-018-0615-x
Schoffelen, P. FM., Plasqui, G., 2017. Utilization of Different Formulae to Calculate Energy Expenditure from Gas Exchange and Substrate Oxidation; an Updated Equation for Indirect Calorimetry. In Schoffelen, P. F. M., 2017. Measurement of Human Energy Expenditure: Biological Variability and Technical Validity [PhD thesis]. Maastricht University. https://doi.org/10.26481/dis.20170914ps
Schoffelen, P. F. M., 2017. Measurement of Human Energy Expenditure: Biological Variability and Technical Validity [PhD thesis]. Maastricht University. https://doi.org/10.26481/dis.20170914ps
Surić, M., Lončarić, R., Kulišić, M., Sršen, L.,2021. Spatio-Temporal Variations of Cave-Air CO2 Concentrations in Two Croatian Show Caves: Natural vs. Anthropogenic Controls. Geologia Croatica, 74 (3): 273–86. https://doi.org/10.4154/gc.2021.21
Šebela, S., 1998. Tektonska Zgradba Sistema Postojnskih Jam / Tectonic Structure of Postojnska Jama Cave System. Vol. 18. ZRC. ZRC SAZU, Založba ZRC. https://doi.org/10.3986/961618265X
Šebela, S.,Turk, J., 2018. Črna Jama as a Cold Air Trap Cave within Postojna Cave, Slovenia. Theoretical and Applied Climatology, 134 (3–4): 741–51. https://doi.org/10.1007/s00704-017-2304-5
The Engineering ToolBox, 2004. Specific Heat Capacity of Air: Isobaric and Isochoric Heat Capacities at Various Temperatures and Pressures. https://www.engineeringtoolbox.com/air-specific-heat-capacity-d_705.html [Accessed 10 November 2025].
Republike Slovenija, 2018.Uredba o nacionalnem radonskem programu. Uradni list Republike Slovenija, 18. https://www.uradni-list.si/glasilo-uradni-list-rs/vsebina/2018-01-0799 [Accessed 10 November 2025].
Downloads
Published
How to Cite
Issue
Section
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors guarantee that the work is their own original creation and does not infringe any statutory or common-law copyright or any proprietary right of any third party. In case of claims by third parties, authors commit their self to defend the interests of the publisher, and shall cover any potential costs.
More in: Submission chapter
