Spatial distribution of natural radioactivity levels in topsoil around the high-uranium mineralization zone of Kylleng-Pyndensohiong (Mawthabah) areas, West Khasi Hills District, Meghalaya, India

A study of background radiation and the distribution of radionuclides in the environment of the proposed uranium mining sites of Kylleng-Pyndensohiong (Mawthabah) areas, West Khasi Hills District, Meghalaya, India, has been carried out with the objective of establishing a baseline radiation level of the region. Topsoil samples collected from the region are analysed for radioactivity measurements of primordial radionuclides by gamma-spectrometry technique. Direct dose measurement using a survey meter was also carried out simultaneously. Measurement carried out in the region shows that the activity concentration of ²³⁸U and ²³²Th in soil samples is found to be highest in Kylleng with respective median values of 335.3 Bq kg^-1 and 283.9 Bq kg^-1 followed by Syngkai with activity concentration of 285.3 Bq kg^-1 and 257.4 Bq kg^-1 for ²³⁸U and ²³²Th, respectively. The distribution of ⁴⁰K concentration in the study area is found to be in the range of 173.1-359.0 Bq kg^-1 which is below the global and Indian average values of 420 Bq kg^-1 and 394 Bq kg^-1, respectively. The contribution of the primordial radionuclides to the total dose of the study area is found to be very high with a range of 136.8-334.5 nGy h^-1 in comparison to the global as well as Indian average values