Estimation of radionuclides in the soil samples from the uranium mining zone of Sikar, Rajasthan, India

The presence of underlying uranium deposits may contaminate the upper soil of a region. We have carried out a detailed investigation of radionuclides (Ra, Th, and K) present in the soil around the reported uranium deposit site in the Sikar district of Rajasthan, India. Measurements are carried out using the state-of-the-art gamma-ray spectroscopy (HPGe detector) technique. The specific activity of ²²⁶Ra, ²³²Th, and ⁴⁰K are found in the range of 9.5 ± 0.5-50.6 ± 1.0 Bq kg^-1, 11.0 ± 0.4-83.2 ± 1.5 Bq kg^-1, and 177 ± 13-753 ± 47 Bq kg^-1 with the mean values of 17.8 ± 7.5 Bq kg^-1, 22.6 ± 13.4 Bq kg^-1, and 393 ± 76 Bq kg^-1 respectively. The average value of Ra Eq. activity is 80.4 Bq kg^-1, below the recommended limit of 370 Bq kg^-1. For radiological implications in the study area, the indoor and outdoor absorbed dose rates and age-dependent annual effective dose are estimated, which are also found below their prescribed safe limit values. The mean value of other hazard indices (H_in and H_ex) and level indices (I_α and I_γ) are less than unity. Our study shows that the underlying uranium deposits do not contaminate the soil of the studied area and the soil is safe to use for various purposes. (author)