MEASUREMENT OF NATURAL RADIOACTIVITY IN DRILLED AND DUG WELL-WATERS OFOGUN STATE, SOUTHWESTERN, NIGERIA AND CONSEQUENT DOSE ESTIMATES

Abstract

Natural radioactivity was measured in twenty samples of well water collected from hand dug wells and drilled wells (boreholes) from Ogun State, Southwestern Nigeria with a view to provide baseline data on radioactivity level in the area, and also to estimate the resulting annual effective dose to the inhabitant as a result of drinking from these well waters. Using high-resolution gamma spectrometry technique, the activity concentrations of the following radionuclides: 4oK,214Bi,214Pb,226Ra and 228Ac were found to be having a mean activity concentration of 2.98±1.90, 2.21±0.18, 2.10±0.53, 4.47±1.13 and O.62±O.24Bq 1-1 respectively. The total annual effective dose due to the ingestion of the natural radionuclides of 4oK, 214Bi, 214Pb, 226Ra and 228Ac for ages 2-7, ]2-17, and >17yrs were estimated to be 0.82, 3.89, and 0.89 mSv y -1 respectively. These values are found to be above 0.1 mSv y -1 of WHO recommended limit for radiological safe drinking water.