Abstract
Radon is a radioactive gas produced from the natural radioactive decay of uranium and is found in almost all rocks and soils. In confined places (e.g., dwellings, workplaces, caves, and underground mines), radon may accumulate and become a substantial health risk since it is considered the second most important cause of lung cancer in many developed countries. Radon risk assessment commonly considers either field or estimate values of the radon concentration and the gas permeability of soils. However, radon risk assessment from single measurement surveys to radon potential largescale mapping is strongly sensitive to the soil texture variability and climate changes, and particularly, to the soil water content dynamic and its effect on soil gas permeability. In this paper, the gas permeability of soils, and thus, the estimation of radon risk, is studied considering the effect of three different climates following the Köppen classification and four soil textures on soil water content dynamics. This investigation considers the CLIGEN weather simulator to elaborate 100-year length climatic series; Rosseta 3 pedotransfer function to calculate soil hydraulics parameters, and the HYDRUS-1D software to model the dynamics of water content in the soil. Results reveal that climate strongly affects gas permeability of soils and they must be considered as an additional factor during the evaluation of radon exposure risk. The impact of climate and texture defines the soil water content dynamic. Coarse soils show smaller gas permeability variations and then radon risk, in this case, is less affected by the climate type. However, in clay soils, the effect of climate and the differences in soil water content derive in gas permeability variations between 100 and 1,000 times through an annual cycle. As a result, it may cross the boundary between two radon risk categories. Results deeply confirm that both climate and texture should be compulsory considered when calculating the radon exposure risk and in the definition of new strategies for the elaboration of more reliable geogenic radon potential largescale maps.
Highlights
Radon, 222Rn or just Rn, is a radioactive gas naturally present in almost all rocks and soils of the Earth’s surface and it is the most important source of ionising radiation among those that are of natural origin [1]
The present study considers three climatic scenarios, according to the Köppen classification trying to represent most common climates in Europe: Bsk, cold semi-arid climate, typical from many regions in South Europe; Csa, temperate Mediterranean climate with dry hot summers and moderate winters, common in South Europe; and Dfb, humid continental climate with cool winters and moderate summers, typical from central Europe
The consequence of this feature is the dominance of dry soils along most months during the year. This situation increases the movement of gas through soils and even favours the development of shrinkage cracks in swelling soils, which will enhance the radon movement. This fact of higher potential evapotranspiration (ET0) than precipitation is observed in the temperate Mediterranean climate (Csa), with more than 1,300 mm of ET0 and 427 mm of average total annual precipitation (Figure 1B)
Summary
In confined places (e.g., dwellings, workplaces, caves, and underground mines), radon may accumulate to higher concentrations where it may pose a substantial health risk [3]. The exposure to the alpha particles from the radon and its short-lived progeny decays does affect the lung tissues, and the skin outer layer where is irradiated as the first barrier in the human body [4,5,6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
