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

The paper presents the results of a radiometric survey carried out on the eastern flank of Mt. Etna over an area of approximately 120 km(2). Activity concentrations of U-238,U-234, Th-232,Th-230,Th-228, Ra-226,Ra-228, from U-238 and Th-232 decay chains, and potassium K-40 were determined using alpha- and gamma- spectrometry techniques. All rock samples presented activity concentrations of U, Th and Ra isotopes ranging from 20 Bq kg(-1) to about 90 Bq kg(-1), and they showed no particular compositional variations over the investigated area. Based on their respective elemental concentrations, the isotopic ratios of different elements were studied to check 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, and the radiological risk resulting from ingestion of these isotopes contained in drinking water was calculated. The results were compared with current regulations on the quality of drinking water.