Radon concentration in groundwater of north-eastern Sicily (Italy)

This paper presents analyses of 222Rn activity concentration performed on groundwater samples collected from wells and natural springs in 70 different sites of the crystalline area of north-eastern Sicily (southern Italy), up to now poorly studied. Alpha spectroscopy of the short-lived radon progeny was used to measure the 222Rn activity concentration by means of the Durridge RAD7 + H2O setup. Radon concentrations were derived to be in the range of 1.6–57.5 Bq L-1. The higher values were detected along fluvial valleys and in the crystalline reliefs, whereas aquifers hosted in the alluvial plains show lower radon concentrations. The annual effective dose due to intake of radon by ingestion ranges from 4 to 146.8 μSv y-1. The average value (56.5 μSv y-1) is below the recommended limit of 100 μSv y-1 proposed by the World Health Organization (WHO). In addition, all the measured radon values are lower than the reference level of 100 Bq L-1 set by the Italian legislative decree 28/2016 and by the European Directive 2013/51/Euratom. Therefore, all sampling sites are fully compliant with the legislative requirements in terms of radon levels. Moreover, results show that the radon levels measured in groundwater from north-eastern Sicily are similar to those determined for the adjacent area of southern Calabria, promoting the assumption of a uniform radon signature in the crystalline domain of southern Italy. However, further studies are needed to define better the role of tectonic activity on the content of dissolved radon in groundwater.