Natural Radioactivity and Associated Dose Rates in Soil Samples of Malnichera Tea Garden in Sylhet District of Bangladesh

The activity concentrations of naturally occurring radionuclides 226Ra, 232Th and 40K, were measured by using a Broad Energy Ge (BEGe) detector for soil samples collected from the Malnichara tea garden in Sylhet district of Bangladesh. The average activity concentrations of 226Ra, 232Th and 40K in soil samples were found to be 55.284±4.68, 125.270±5.81 and 497.91±43.83 Bqkg-1, respectively. The results obtained for the corresponding nuclides are slightly higher than the worldwide average values of 35, 30, and 400 Bqkg-1, respectively. The average outdoor absorbed dose and the annual effective dose rates due to 226Ra, 232Th and 40K were observed to be 124.12 ± 7.59 nGyh-1 and 152.22±9.31 μSvy-1, respectively; which are above the world average. Whereas, the radium equivalent activity and external hazard indices are less than the world average values.