Naslov
What controls short-term variations in CO2 and 222Rn concentrations in Modrič Cave atmosphere?

Autori
Surić, Maša ; Lončarić, Robert ; Radolić Vanja ; Miklavčić, Igor

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
30th International Karstological School "Classical Karst": Karst Approaches and Conceptual Models, Abstracts & Guide Book / Švara, Astrid ; Zupan Hajna, Nadja ; Gabrovšek, Franci - Postojna : Založba ZRC SAZU, 2023, 153-153

ISBN
978-961-05-0747-5

Skup
30th International Karstological School "Classical Karst": Karst Approaches and Conceptual Models

Mjesto i datum
Postojna, Slovenija, 19.06.2023. - 23.06.2023

Vrsta sudjelovanja
Poster

Vrsta recenzije
Podatak o recenziji nije dostupan

Ključne riječi
CO2, radon, cave monitoring, Croatia

Sažetak
What controls short-term variations in CO2 and 222Rn concentrations in Modrič Cave atmosphere? Radon (222Rn), as a naturally occurring radioactive geogenic gas, presents potential health hazard in confined, poorly ventilated areas such as caves. Thus, in order to ensure safe work environment for the guides and cave scientists, it is necessary to determine precise temporal and spatial variations of radon concentrations. In Modrič Cave (littoral Croatia), small (829 m) two-branch horizontal show cave, we conducted 6.5-years and 5-years monthly measurements of CO2 and Rn concentrations, respectively, which revealed basic ventilation pattern ; it is seasonal density-driven air circulation controlled by the difference between outside and cave air temperature on which cave morphology and bedrock architecture are superimposed. Aiming to decipher short-term variation with respect to meteorological conditions (precipitation, wind), additional continuous measurements of cave-air concentration of Rn and CO2 began in 6/2020 and 10/2021, respectively. Bearing in mind that the highest gas concentrations (~24, 000 Bq/m3 and ~12, 000 ppm) were recorded in summer during the peak tourist season, sudden gases concentration increase/decrease governed by intensive precipitation/bora wind should be respected in terms of cave management. Since the radon underground pathways could be affected by the phenomena that precede or accompany the earthquakes we considered 13 earthquakes – 8 nearby (7-56 km) with magnitude M 2.1-4.7 and 5 distant earthquakes (115-175 km) with greater magnitude M 4.8-6.2, but no significant radon flux has been recorded. However, it could have been masked by other environmental features, especially during the warm periods when both radon and CO2 as its carrier gas, are intensively produced in the soil horizon by plant respiration, microbial activity and limestone dissolution that enhances radon release.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Geologija, Interdisciplinarne prirodne znanosti, Geografija

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