Measurement of natural radioactivity and radiological hazard evaluation in the soil samples collected from Owo, Ondo State, Nigeria

The activity concentrations of K-40, Ra-226, and Th-232 in the soil samples collected from Owo Local Government of Ondo state, Nigeria, were assessed by gamma spectrometric techniques using a Na(TI) scintillation detector, encapsulated in a 5x5-cm-thick lead shield to reduce environmental background radiation. Results show that the ranges (and the corresponding average) of the measured activity concentrations of K-40, Ra-226, and Th-232 are 430.15 +/- 4.12 to 2100.42 +/- 11.89 BqKg(-1) (1190.10 +/- 373.62 BqKg(-1)), 31.58 +/- 2.94 to 212.11 +/- 13.15 BqKg(-1) (64.64 +/- 28.10 BqKg(-1)), and 16.27 +/- 7.10 to 203.09 +/- 42.64 BqKg(-1) (110.18 +/- 46.12 BqKg(-1)), respectively. The average activity concentrations of the radionuclides were compared with the world average value. Radiological hazard indices of the primordial radionuclides were also calculated and compared with the recommended standard exposure limits. The absorbed dose rates estimated in the study were used to create the absorbed-dose rate map of the study area, showing the geological feature of the same. Generally, the results showed that the soil in the study area might not pose significant hazards to members of the public. However, further investigations into the level of exposure of plants and animals as well as the ingestion of radionuclide are necessary.