Naturally Occurring Radionuclide Variation with Soil Depth Profile of Udi and Ezea Local Government Areas of Enugu State, Nigeria

The assessment of the natural radionuclide concentration with depth profile of two drilled borehole in Enugu State Nigeria have been carried out using gamma spectroscopy detector. Soil samples were collected at 20meters depth interval down the boreholes (wells) with a depth of about 200m and 140m for Well 1 (Amagu-Umuene) and Well 2 (Ogulogu-Olo) respectively. The average values 40K, 226Ra and 232Th obtained is 57.17Bq/kg, 13.71Bq/kg and 10.49Bq/kg respectively for Well 1 and 59.77Bq/kg, 11.49Bq/kg and 8.83Bq/kg respectively for Well 2. The computed absorbed dose and equivalent dose rate has a mean value of 15.20ηGy/hr and 0.13mSv/yr for Well 1 and 13.30ηGy/hr and 0.12mSv/yr for Well 2 respectively. These values obtained are well within the world average value and may not constitute any significant health effects to human and environmental hazard. The variation of the radionuclides for both wells is irregular down the depth of the boreholes profile. The irregular distribution pattern down the aquifer is attributed to the mineralogy and the geology of the study area.