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.