engleski

Changes in CO2 and 222Rn concentrations in cave environment – Modrič Cave (Croatia) case study

Caves are located within the Earth’s Critical Zone (ECZ), which is marked by intensive interactions between atmosphere, biosphere and hydrosphere. Temporal changes in these interactions can be recorded in cave sediments (i.e. speleothems) which led to caves and cave sediments being extensively used in various palaeoenvrionmental and palaeoclimatical studies. Within those researches, the need for long-term environment monitoring emerged as a necessity. Furthermore, monitoring programmes have also provided valuable data for show caves’ sustainable management. We present the results of ongoing continuous measurement of CO2 and 222Rn concentrations in the Modrič Cave (Croatia), a relatively small show cave located at the foothills of the Velebit Mt. near Adriatic coast at 32 m a.s.l. It is a simple cave with two mainly horizontal passages with total length of 829 m. Previous monitoring campaigns in the Modrič Cave with monthly and seasonal resolution showed strong seasonal changes in CO2 concentrations with two distinctive seasons: summer/autumn with the highest, and winter/spring with the lowest values. The 222Rn concentration in the cave air follows spatial and temporal patterns similar to the CO2 concentrations. Monitoring data also showed significant differences in cave air CO2 and 222Rn concentrations between the two main passages. The diverse features of the two passages can explain these differences as the wider left passage is well ventilated in comparison to the more constrained right passage. The continuous logging of cave air CO2 and 222Rn launched in 2021 provided high-resolution data, which revealed sudden variations in both CO2 and 222Rn concentrations that had not been detected in the previous campaign as they occur on smaller time scales. Apparently, these peaks concur with intensive rain events indicating more dynamic cave atmosphere system than previously thought, which will affect future (palaeo)environmental studies in this cave.

caves, monitoring, CO2, radon, Croatia

nije evidentirano