Studies on Radon Exhalation Rate and Activity of Radioactive Elements in Soil Samples and their Radiological Hazards to the Population of Davanagere District, Karnataka, India

Abstract

Exhalation rate of 222Rn from soil samples and the activity concentrations of 226Ra, 232Th and 40K were studied in soil samples of Davanagere district, Karnataka state, India. 222Rn exhalation rate was measured using smart radon monitor (SRM). The mass exhalation rate of 222Rn varies from 6.9 ± 1.7 to 38.5 ± 3.3 mBqkg-1h-1 with a geometric mean of 20.1 ± 2.5 mBqkg-1h-1. The surface exhalation rate of 222Rn varies from 0.39 ± 0.1 to 2.15 ± 0.18 Bqm-2h-1 with a geometric mean of 1.12 ± 0.14 Bqm-2h-1. Activity concentrations of the radionuclide in soil samples were measured using HPGe detector. 226Ra, 232Th and 40K concentration varied from 32.0 to 106.1 Bqkg-1, from 19.6 to 78.8 Bqkg-1 and from 20.1 to 968.0 Bqkg-1 respectively. The average activity of 226Ra in the soil samples was 63.2 Bqkg-1 which is higher than the global average and the Indian average value, whereas the activities of 232Th and 40K were found to be 34.9 Bqkg-1 and 458.8 Bqkg-1 respectively and are comparable to global average values. When the structural and physical properties of the soil samples were similar, radon exhalation rate from soil samples shows good correlation with its 226Ra activity.