Measurement of radioactivity level of oil-contaminated soils around mechanic workshops for environmental impact assessment

Abstract

ABSTRACT This study identified and quantified the naturally occurring radionuclides, evaluated the levels of radiological hazard indices using the radionuclide activity concentrations and assessed their contamination status of the soils around mechanic workshops in Akure, Nigeria. Samples of oil-contaminated and control soils were, respectively, collected from mechanic workshops areas and areas with little or no anthropogenic activities within Akure, Ondo State, Nigeria and the activity levels of the radionuclides were determined using gamma-ray spectrometry. The radionuclides obtained with reliable regularity are associated with the decay series of 238U and 232Th as well as the non-decay series 40K. The results showed that the mean activity concentrations of the radionuclides 232Th, 238U and 40K in the oil-contaminated soils were 0.89 ± 0.08, 132.13 ± 0.16, and 51.52 ± 0.06 Bq/Kg, respectively. The radiological assessments in terms of the mean values of absorbed dose rate were (63.93 nGy/hr), annual equivalent dose rate (0.55 mSv/yr), internal hazard index (0.72 Bq/Kg), external hazard index (0.37 Bq/Kg), annual gonadal dose equivalent (428.22 µsvy−1), representative gamma index (0.92), and radium equivalent (137.38 Bq/Kg). Thus, radiological assessment indicated that long-term exposure of the radionuclides might pose integral hazards to human health.