Dependence of Natural Radioactivity on the Mineralogy of Rocks and the Assessment of Radiological Hazards in Dharwad Region of Karnataka, India

The natural radioactivity in rock and dependence of the radioactivity on the mineralogy of rocks in the Dharwad region of Karnataka, India, were studied. The radionuclide activity in rocks was analyzed using a NaI(Tl) gamma-ray spectrometer, and the mineralogy was studied using FTIR spectroscopy and X-ray diffraction. The activity concentrations varied from 105 ± 2 to 783 ± 7 Bq kg–1 for 40K, from 2 ± 0.5 to 63 ± 2 Bq kg–1 for 226Ra, and from 10 ± 1 to 65 ± 2 Bq kg–1 for 232Th, with mean activity of 511 ± 6, 31 ± 2, and 39 ± 1 Bq kg–1, respectively. The activities of natural radionuclides were found to be slightly higher for 40K and 232Th but lower for 226Ra. The radiation hazard indices were determined to assess the radiation exposure of the region’s population. The study showed that elevated 40K and 232Th levels in the region are due to the presence of potassium-rich biotite, silicate-bearing feldspar, and phosphate mineral monazite present in the rocks of the region.