Application of Natural Radionuclide in the Subsurface Hydrogeology of Selected Two Local Governments in South Western Nigeria
This research investigated the use of radioactive isotopes to study the underground water characteristics of Ife South and Ife North Local governments area of Osun state in Southwestern Nigeria. The study aimed to determine the origin of water, the flow paths, residence time, and prediction of the geological formation of the study area. Twelve water samples were collected from the two local governments using standard methods for isotope study. Uranium 234U and 238U were analyzed for water samples using a gamma-ray spectrometer with Caesium Iodide (CsI) scintillation detector and physical analyses such as pH, electrical conductivity, total dissolved solids, and temperature were also determined. The specific activity of 238U ranged between 27.44±0.55 to 36.89±1.70 Bq/kg; activity ratio of water samples from the two LGA ranged from 0.83 to 1.07 with average activity ratio of 0.901. All the sample locations have an activity ratio of less than 1.00 except two locations in Ife South LGA (Ooni 1 and 2); a 234U value of 30.386747 Bq/kg was taken as constant. Ife North and Ife South have an average EC, turbidity, TDS, residence time of 493.3 (µs/cm), and 686.6 (µs/cm); 1.2 NTU and 3.33 NTU; 108.67 mg/l and 523.33 mg/l; 2.889 ma and 2.784 ma respectively. In conclusion, the groundwater of the two LGA originate from the same source and are in the oxidation state; aquifers within Ife North and Ife South are separated with a barrier; hence its groundwater does not flow through one another. The residence time of groundwater in the two LGA is over 2.8 ma; Ooni 1 and 2 area is underlain by rocks rich in Uranium (granite), rocks underlying Ife South is younger to Ife North, Ife North is underlying by old weathered rocks (sedimentary rocks).
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Copyright (c) 2020 Julius Olatunji Jeje, PhD, Kamar Taiwo Oladepo, PhD
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