The radionuclide contents of sediment samples collected from 20 surface-water dams in southwestern Nigeria have been determined by low-level gamma-spectroscopy. The average concentration of 40K in each of the dams varied between 110.9 ± 11.9 Bq kg-1 and 1025.9 ± 36.8 Bq kg-1 with an overall mean (± SD) of 549.3 ± 247.6 Bq kg-1 while that of 238U varied from 17.1 ± 3.6 to 51.9 ± 8.7 Bq kg-1 with an overall mean (± SD) of 27.6 ± 8.5 Bq kg-1 and that of 232Th varied from 26.2 ± 3.6 Bq kg-1 to 130.1 ± 23.7 Bq kg-1 with overall mean (± SD) of 62.0 ± 26.1 Bq kg-1. The variability of the values shows the wide disparity in the measured activity concentrations. The mean radium equivalent of 158.9 Bq kg-1 was calculated for the sediments in the dams. No artificial gamma emitting radionuclide was detected in the samples.
