Radon Dynamics in Granite and Calcareous Soils: Long-Term Experiments in a Semi-Arid Context

Radon in soil poses a significant health risk when it accumulates inside dwellings. The estimation of radon potential is a difficult task due to the complex dynamics of radon within soil and its relations with the weather. This research focuses on the variability of radon activity, driven by environmental changes, assessed in two loam soils (loamy sand–granite soil and silty clay loam-calcareous soil) with different radium contents. We conducted an experiment with teow soil columns in a semi-controlled outdoor laboratory, in a warm semi-arid climate. We also examined the consequences of abundant rainfall on radon activity through artificial soil water content (SWC) experiment conditions. Statistical analyses reveal that SWC is the most significant parameter influencing radon activity in these experiments. Radon is proportional to SWC and inversely proportional to temperature, evapotranspiration, and pressure in both soils, while wind is negatively related only in the loamy sand soil. Based on our findings, we modelled radon potential considering different soils and climatic contexts. SWC influences radon potential by changing radon emanation, activity, and permeability, depending on the local soil texture and radium concentration.