Radiological Hazard Indices and Dose Rates From 238U, 232Th, and 40K in Soils of Mining Areas of Northern Rajasthan

Abstract In this study, high-purity gamma-ray spectroscopy was used to determine activity concentrations of naturally occurring radionuclides (226Ra, 232Th, and 40K) in soil samples from red-granite mining areas of Jodhpur and marble-mining areas of Nagpur in northern Rajasthan, India. The measured activity concentrations ranged from 18±5 to 39±7 Bq kg−1 for 226Ra, 47±2 to 78±6 Bq kg−1 for 232Th, and 328±6 to 823±8 Bq kg−1 for 40K. From these data, radiological hazard parameters were calculated: the radium-equivalent activity (Raeq) ranged from 108 to 208 Bq kg−1, absorbed dose rates from 51 to 101 nGy/h, annual effective dose rates from 0.35 to 0.68 mSv, external hazard indices (Hex) from 0.25 to 0.48, and internal hazard indices (Hin) from 0.35 to 0.68. All values were well below internationally accepted safety limits. The mean Radium equivalent activity (Raeq) of 158 Bq kg−1 is far below the recommended limit of 370 Bq kg−1 and both hazard indices are well below unity. These results indicate negligible radiological risk, suggesting that the soils in the studied areas have only background levels of natural radio activity and are safe for use in construction without significant radiological hazards.