Determination of natural Radioactivity in Groundwater in Tanke - Ilorin, Nigeria

A study of the radioactivity in groundwater from Tanke-Ilorin, Nigeria, has been carried out. Ten water samples were analyzed by ϒ-ray spectroscopy to determine the 226 Ra and 228 Ra concentrations. The activity  concentration values range from 0.81 ± 0.08 to 7.4 ± 2.2 Bq/l for 226 Ra and from 1.8 ± 0.3 to 5.6 ± 2.6 Bq/l for 228 Ra. The derived Annual Effective Dose received by the population as a result of the ingestion of 226 Ra was estimated to range from 0.08 ± 0.01 to 0.12 ± 0.07 mSv/y with an average of 0.39 ± 0.11 mSv/yand 228 Ra range from 0.50 ± 0.32 to 1.42 ± 0.70 mSv/y with an average of 0.91 ± 0.31 mSv/y. Consequently, the Annual Effective Dose received, as a result of the combined ingestion of 226 Ra and 228 Ra, was found to range from 0.81 to 1.74 mSv/y with an average of 1.30 mSv/y. The mean contribution of both 226 Ra and 228 Ra activities to the committed effective dose from a year’s consumption of drinking water in the study area is, therefore, higher than the tolerable level of 1 mSv/y to the general public for prolonged exposure as recommended by ICRP, and much more than the new WHO recommended level of 0.1 mSv/y for drinking water.