Mapping the geogenic radon potential and radon risk by using Empirical Bayesian Kriging regression: A case study from a volcanic area of central Italy

A detailed geochemical study on radon related to local geology was carried out in the municipality of Celleno, a little settlement located in the eastern border of the Quaternary Vulsini volcanic district (central Italy). This study included soil-gas and terrestrial gamma dose rate survey, laboratory analyses of natural radionuclides (U-238, Ra-226, Th-232, K-40) activity in rocks and soil samples, and indoor radon measurements carried out in selected private and public dwellings. Soil-gas radon and carbon dioxide concentrations range from 6 to 253 kBq/m(3) and from 0.3 to 11% v/v, respectively. Samples collected from outcropping volcanic and sedimentary rocks highlight: significant concentrations of U-238, Ra-226 and K-40 for lavas (151, 150 and 1587 Bq/kg, respectively), low concentrations for tuffs (126, 123 and 987 Bq/kg, respectively), and relatively low for sedimentary rocks (108, 109 and 662 Bq/kg, respectively). Terrestrial gamma dose rate values range between 0.130 and 0.417 mu Sv/h, being in good accordance with the different bedrock types. Indoor radon activity ranges from 162 to 1044 Bq/m(3); the calculated values of the annual effective dose varied from 4.08 and 26.31 mSv/y.