Radon concentration in cave may sometimes reach high values depending on bedrock characteristics, caveconfigurations, groundwater and ventilation. The naturally occurring Rn behaviour in cave environment is ofgreat interest, especially within showcaves where this gas can lead cave workers exposed to hight radon activityto a considerable health risk. In this study, the radon concentration was measured in Su Mannau Cave (Fluminimaggiore, SW Sardinia, Italy)cave atmosphere with the aim to provide a reliable distribution of this trace gas at a spatio-temporal scale. Thiscave is hosted in Cambrian carbonates belonging to the Iglesiente region, a complex Pb-Zn mining district. Itdevelops for more than 8 km, with large rooms and long tunnels with mostly horizontal profile and only fewvertical drops. A comprehensive radon survey has been carried out along the tourist path of the Su Mannau cave from February2019 to April 2020. The results reveals that radon concentration ranges from 300 Bq m to 3,450 Bq m . The lowest values wasrecorded close to the entrance and the highest one at the end of the tourist path where the main cave passagesis connected to a lateral branch. A spatial gradient has been observed along the vertical profile of the cave indicating that there is no equilibriumbetween the gas mixed with the underground atmosphere. Spatial and seasonal cave CO2 concentrations followed the same trend. Different factors, such as seasonal cave meteorological effects, groundwater, sedimentcomposition and rock porosity, could possibly influence this pattern. Further investigations could explain thisaspect.
Temporal and spatial variation for radon concentrations in the Su Mannau cave (Fluminimaggiore, Italy)
Laura Sanna;
2021
Abstract
Radon concentration in cave may sometimes reach high values depending on bedrock characteristics, caveconfigurations, groundwater and ventilation. The naturally occurring Rn behaviour in cave environment is ofgreat interest, especially within showcaves where this gas can lead cave workers exposed to hight radon activityto a considerable health risk. In this study, the radon concentration was measured in Su Mannau Cave (Fluminimaggiore, SW Sardinia, Italy)cave atmosphere with the aim to provide a reliable distribution of this trace gas at a spatio-temporal scale. Thiscave is hosted in Cambrian carbonates belonging to the Iglesiente region, a complex Pb-Zn mining district. Itdevelops for more than 8 km, with large rooms and long tunnels with mostly horizontal profile and only fewvertical drops. A comprehensive radon survey has been carried out along the tourist path of the Su Mannau cave from February2019 to April 2020. The results reveals that radon concentration ranges from 300 Bq m to 3,450 Bq m . The lowest values wasrecorded close to the entrance and the highest one at the end of the tourist path where the main cave passagesis connected to a lateral branch. A spatial gradient has been observed along the vertical profile of the cave indicating that there is no equilibriumbetween the gas mixed with the underground atmosphere. Spatial and seasonal cave CO2 concentrations followed the same trend. Different factors, such as seasonal cave meteorological effects, groundwater, sedimentcomposition and rock porosity, could possibly influence this pattern. Further investigations could explain thisaspect.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
