Investigation of Radionuclide Levels in Groundwater Around Transmission Company of Nigeria for Environmental Impact Assessment

Abstract

The activity concentrations of 40K, 238U and 232Th in groundwaters taken from areas surrounding Transmission Company of Nigeria, Osogbo, Nigeria were measured to highlight and ascertain possible radionuclide pollution. High-resolution gamma spectrometry (HPGe detector) was used to determine the activity concentration of these radionuclides and the results obtained were used to calculate human radiological risk by the inhabitants in the area. The activity concentrations of 40K in all the groundwater samples range from 53.48 ± 2.90 to 407.58 ± 20.94 Bq/L. The activity concentrations of 238U in the groundwaters range from BDL to 21.86 ± 3.05 Bq/L. The activity concentrations of the 232Th in the groundwaters range from 2.18 ± 0.14 to 11.76 ± 0.68 Bq/L. Of the three investigated radionuclides, 40K was observed to have the highest mean activity concentration. The radiological parameters indicated mean values of 15.25 nGy/hr as the absorbed dose rate, 0.13 mSv/yr as the annual effective dose, 0.10 Bq/kg as the internal hazard index, 0.08 Bq/L as the external hazard index, 110.02 µsvy-1 as the annual gonadal dose equivalent, 0.24 as the representative gamma index and 31.11 as the radium equivalent. These suggested that the groundwaters do not pose intrinsic radiological hazards as a result of their relatively lower values than the UNSCEAR permissible levels. As a result of this, the occurrence of any heath effect due to radiation is low. These measurements therefore represent baseline values of these radionuclides in the ground waters of the studying area and further monitoring of these groundwaters should be encouraged.