Investigation of gamma radiation levels in soil samples collected from some locations in Ogun State, Nigeria.

This study measured the terrestrial gamma radiation and associated dose rates from primordial radionuclides 238U, 40K and 232Th in sixty soil samples collected from north, west, east and south of Ewekoro cement factory premises, Owowo village situated adjacent the factory and Covenant University, Ogun State using gamma ray spectrometry method. In order to estimate the radiological hazard index of the natural radioactivity, the gamma absorbed dose rate, annual effective dose and hazard indices were estimated. The measured activity concentrations of radionuclides in Ewekoro cement factory soils [238U {1.60±1.60 Bqkg−1 (east) - 2.56±0.08 Bqkg−1 (north)}, 232Th {44.78±1.83 Bqkg−1 (east) - 56.62±1.96 Bqkg−1 (north)}, 40K {261.54±12.67 Bqkg−1 (south) - 342.08±14.17 Bqkg−1 (east)}] and Owowo village [238U {1.78±0.09 Bqkg−1 (east) - 2.62±0.08 Bqkg−1 (north)}, 232Th {50.07±1.93 Bqkg−1 (west) - 61.69±1.89 Bqkg−1 (north)}, 40K {244.11±13.38 Bqkg−1 (north) - 296.40±14.90 Bqkg−1 (south)}] soils are higher than that of Covenant University soils [238U {0.62±0.07 Bqkg−1 (south) - 1.07±0.06 Bqkg−1 (north)}, 232Th {30.23±1.87 Bqkg−1 (south) - 38.87±1.78 Bqkg−1 (east)}, 40K { 243.35±12.57 Bqkg−1 (south) - 301.15±13.55 Bqkg−1 (north)}]. The radiation hazard indices estimated were less than unity, the mean absorbed dose and annual effective dose rates are 40.88 nGyr-1 and 0.05 mSv respectively. The study found that the activity concentrations and radiological hazard index from samples from Ewekoro and the neighbouhood are consistently higher than those from Covenant University however, the values are less than the recommended safe levels