Natural radioactivity in the Alte Madonie Mounts (Sicily, Italy)

Abstract

With the collaboration of geology experts, we have taken 45 samples of selected soils and rocks. All samples were powdered, dried and sealed in “Marinelli” beakers for 20 days before the measurement so as to ensure that radioactive equilibrium between 226Ra and 214Bi has been reached. Mineralogical and chemical features of the samples were determined by XRD and XRF analysis, instead Gamma ray spectrometric analysis was used in order to quantify radioactivity concentrations. The average values of concentrations of 214Bi, 228Ac and 40K are respectively 30, 19 and 258 Bq/kg while the greatest values were 134, 59 and 748 Bq/kg. A linear relationship exists between 214Bi, 228Ac and 40K activities: the activities of 214Bi and 228Ac are comparable, while those of 40K are about 10 times. An exception was highlighted for a group of samples that present 214Bi activities much higher than expectations. The analysis on the chemical composition of the samples made it possible to justify these anomalies, as verified by means of use of the principal components method. Regarding the primordial radionuclide contents, the results are reassuring from the point of view of radiation protection and are interesting about the relationship between the activities of uranium and thorium series products and the activity of 40K.