Assessment of Radionuclide Concentrations in Water Supply from Bore-holes in Ogbomosoland, Western Nigeria

The level of radionuclide concentration in water from bore-holes in selected areas of Ogbomosoland, a region consisting of five local governments, was determined. Concentration of 238U, 232Th, and 40K was determined for the water samples from eight bore-holes around Ogbomosoland by γ-ray spectrometry with a high-purity germanium (HPGe) detector connected to a multichannel analyzer. All the water samples from these bore-holes were found to contain acceptable levels of radionuclides with mean activity values of 3.98 ±0.26, 11.00 ±2.58, and 17.73 ± 5.04 Bql -1 for 40K, 232Th, and 238U, respectively showing that the mean activity of 238U for all the samples is the highest when compared with those of 40K and 232Th. Water samples from Ikoyi had the highest radionuclide content although 40K concentration was below detectable level. Water samples from Gambari were next to Ikoyi in radionuclide content, followed by Saja, Ajinopai, Kajola, Isale-Ora, Iresa-Apa, and Owode in that order. The mean absorbed dose rate for all the area is 0.123 mSvyr-1 which is very low when compared to the recommended limit of 1mSvyr-1 for bore-hole water. Overall, the radionuclide concentration of the bore-hole water supply in Ogbomosoland is, negligible and poses no radiological hazards to the public.