Assessment of natural radiation in contaminated automobile workshop soils

The presented study aims to identify and quantify the natural radionuclides activity concentrations on the top and sub-soils around mechanic workshops in Ojo and Ijegun, Lagos, Nigeria. Based on these measured radionuclides activity concentrations, radiological hazard indices are assessed. Twenty oil-contaminated soil samples were collected, and the levels of natural radionuclides activity are measured by applying gamma spectrometry The measured radionuclides with authoritative regularity are linked with the natural decay series of ²³⁸U (²²⁶Ra) and ²³²Th as well as the series of non-decay ⁴⁰K. The obtained results show that the mean radionuclides activity concentrations in the collected oil-contaminated soils samples are 14 ± 4 Bq kg^-1, 105 ± 55 Bq kg^-1, and 90 ± 33 Bq kg^-1, for ²²⁶Ra, ²³²Th, and ⁴K respectively. It was founded that the ²²⁶Ra radionuclide is the lower present in the oil-contaminated soils samples. The radiological assessments were evaluated in terms internal hazard index (0.54), and external hazard index (0.55) both of which are below the UNSCEAR-2000 standard limit. Consequently, the radiological assessment indicated that long-time exposure to those radionuclide's strength confuses integral hazards.