Evaluation of radiological hazards due to natural radioactivity in bituminous soils from tar-sand belt of southwest Nigeria using HpGe-Detector

Background: oil exploration is known to have great impact on theenvironment due the presence of natural radionuclides in crude oil andbitumen. materials and methods: in this study, high purity germanium (hpge)detector was used to determine the activity concentrations of ^40k, ^226ra and^232th in bituminous soil and viscous bitumen samples collected from 5 differentlocations within the tar-sand belt of southwest nigeria. soil samples were collectedalso from a non tar-sand area to serve as control. results: the averageconcentrations of ^40k, ^226ra and ^232th in the bituminous-soil samples were139.32, 28.21 and 27.13 bq kg^-1, respectively for agbabu, 16.09, 18.71 and17.99 bq kg^-1, respectively for ilubirin, 33.98, 38.90 and 29.82 bq kg^-1,respectively for iju oke, 35.01, 30.06 and 21.52 bq kg-1, respectively for odeaye, 7.99, 4.77 and 4.08 bq kg^-1, respectively for ode irele. their respectivevalues were 306.82, 23.52 and 23.14 bq kg^-1 for the non bituminous-soil. thenatural radioactivity levels of ^40k, ^226ra and ^232th in the viscous bitumensamples ranged from below detection level (bdl)-30.74, 2.02-36.33 and3.38-33.71 bq kg^-1, respectively. the estimated gamma dose rate was higherin the non-bituminous soil than that of bituminous soil. conclusion: all theradiation hazard indices estimated in this study are lower than the acceptable limits.it can therefore be concluded that the soil and bitumen samples are safe for use asmaterials for building and road constructions.