Natural radioactivity in a volcanic island: Ustica, Southern Italy

Gamma-ray spectrometric measurements were performed on rocks and soils of the island of Ustica (Southern Italy) to quantify the concentrations of the natural radionuclides. The 238U, 232Th, and 40K concentration ranges (15–164, 16–174, and 201–1350 Bq kg−1, respectively) were compared with mineralogical and chemical data obtained by XRD and XRF analyses. The observed levels of the primordial radionuclides corresponded to the magmatological features of the rocks. Soil samples generally showed specific gamma-ray activities not directly correlatable to those measured in the underlying rocks. A survey was also perormed to measure air kerma in outdoor and indoor environments using thermoluminescent dosimeters. The outdoor values generally were low (less than 700 μGy yr−1) and are compared with the predicted levels calculated from the measured concentrations of the primordial radioisotopes on the rock and soil samples. Radon measurements in both indoor and outdoor environments were also performed. Data collected can be used to evaluate the health impact of the natural radioactivity on the population.