Radioactivity concentrations and dose assessment for bitumen and soil samples around a bituminous deposit in Ondo State, Nigeria

Bitumen samples and soil samples around a bituminous deposit in Ondo State, Nigeria, were analysed for K-40, Ra-226 and Th-232 employing gamma-ray spectrometry. The activity concentrations of K-40, Ra-226 and Th-232 a in soil varied from (45.2 +/- 5.3) to (484.2 +/- 25.9), BDL (below detectable limit) to (27.7 +/- 2.1) and (22.8 +/- 2.7) to (62.4 +/- 6.8) Bq.kg(-1), respectively. The corresponding mean values were (240.2 +/- 133.5), (13.3 +/- 8.0) and (40.0 +/- 10.2) Bq.kg(-1), respectively. The mean activity concentrations of the radionuclides in the bitumen were (58.4 +/- 36.4), (16.1 +/- 13.3) and (32.5 +/- 13.1) Bq.kg(-1) K-40 , Ra-226 and Th-232. l, respectively, for The mean absorbed dose and effective dose for the soil samples were (41.5 +/- 8.9) nGy.h(-1) and (50.7 +/- 10.9) mu Sv.y(-1) respectively, while those of the bitumen samples were (29.5 +/- 15.6) nGy.h(-1) and (36.1 +/- 19.1) mu Sv.y(-1), respectively. For radiological hazard assessment, the radium equivalent activity and the external hazard index were determined. The values of the radium equivalent activity and external hazard index obtained for the soil and bitumen samples were lower than the recommended