Radionuclide concentrations in soils of Northern Namibia, Southern Africa

Activity concentrations of the naturally occurring radionuclides like 238U, 232Th and 40K in 400 soil samples collected from four major towns across the northern region of Namibia have been determined using gamma-ray spectrometry with the objective of providing baseline data on the radiation level in the region. The average concentrations of radionuclides in the towns vary from 7.5 ± 2.3 to 14.2 ± 3.3 Bq kg−1 for 238U, 5.8 ± 2.6 to 24.9 ± 6.1 Bq kg−1 for 232Th and 52.1 ± 28.7 to 380.1 ± 112.9 Bq kg−1 for 40K. These concentrations were used to calculate the mean absorbed dose rate and the mean annual effective dose in the region. The low value of 21 ± 16 µSv obtained for the mean annual effective dose indicates that the region has normal background radiation.