Correlation of radioactivity measurements, air kerma rates and geological features of Sicily.

Sicily, the largest Mediterranean island (with an extension of about 25 000 km2), exhibits a very wide variety of lithologies, ranging from sedimentary to metamorphic and volcanic rocks. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) have been applied to air kerma values measured by thermoluminescent dosimetry in several sites and to data of radionuclide concentrations, geochemical and mineralogical features of rocks and soils sampled in 29 sites of Sicily to point out similarities among different lithologies. The study was devoted to find multiple correlations and allow a better classification of Sicilian lithotypes. Samples of rocks and soils have been analyzed by X-ray fluorescence (XRF), X-ray diffractometry (XRD), and gammaray spectrometry. Major element concentrations, mineralogical data, along with specific activities of 40K, 238U, and 232Th natural radionuclides, have been determined in several samples. Geochemical, mineralogical and petrographic features are in good agreement with radiometric data. A survey was also performed to measure air kerma in outdoor environment using thermoluminescent dosimeters. The measured values were compared with the predicted levels computed from the radioisotope concentrations present in rock and soil samples. Moreover, collected data can be used to evaluate the health impact of the natural radioactivity on the population.