Radioactivity content in volcanic rocks and radionuclides transfer from rocks to groundwater at Mt. Etna volcano

The paper presents the results of a radiological survey carried out on the eastern flank of Mt. Etna over an area of approximately 120 km 2 . Activity concentrations of uranium isotopes 238,234 U, thorium isotopes 232,230,228 Th, two radium isotopes 226,228 Ra from 238 U and 232 Th decay chains and potassium 40 K were determined using the a- and g- nuclear spectrometry techniques. All rock samples presented activity concentrations of U, Th and Ra in the range between 20 Bq/kg to about 90 Bq/kg, showing a comparable radioactivity content in the whole investigated area. Based on their respective elemental concentrations, the isotopic ratios between different isotopes were studied to draw conclusions on the presence of radioactive equilibrium or disequilibrium in the decay chains. Moreover, an attempt to calculate radionuclide transfer factors from soil to water was made. On the basis of the evaluated concentrations, the radiological risk resulting from ingestion of these isotopes with drinking water was calculated. The obtained results were compared with the regulations currently in force regarding the quality of drinking water