study of distribution of 226ra, 232th and 40k in different rock formations and their dose estimation in and around chickmagalur, india

background: the concentrations of radionuclides like 226ra, 232th and 40k and the dose rate are measured in igneous and metamorphic rock formations in and around chickmagalur. a total of 236 samples from 13 different locations around study area were analyzed. materials and methods: the activity concentrations of the three radioactive elements were determined for mean period of 25000 s using hpge (gmx - 10190) detector and the dose calculations were made using standard formulae. results: the mean activity concentrations in igneous rocks recorded were 36.6 bqkg-1, 73.2 bqkg-1 and 992.3 bqkg-1 for 226ra, 232th and 40k respectively. the mean activity concentrations in metamorphic rocks were 17.2 bqkg-1, 28.1 bqkg-1 and 617.8 bqkg-1 for 226ra, 232th and 40k respectively. assuming 20% occupancy factor, the corresponding mean annual effective dose due to igneous and metamorphic rocks were 169.6 µsv and 90 µsv respectively. conclusion: the concentrations of radionuclides were found to be in similar with global and indian average (1-3).