Assessment of Naturally Occurring Radionuclides with Depths in the Soils of Selected Dumpsites, Ogun State, Southwestern Nigeria

Abstract

The assessment of natural radionuclides in sixteen soil samples obtained across
Saje, Oke-Diya, Premier and Ita-Oshin dumpsites, Ogun State, Southwestern Nigeria was
carried out to determine the activity concentrations of 238U, 232Th and 40K and to evaluate
possible health hazards that these radionuclides may pose to inhabitants. The samples were
collected at profile depths of 0-20, 20-40, 40-60 and 60-80 cm using soil auger. The
samples were oven-dried for 24 hours and about 600 g post-sieved samples were sealed for
thirty days before analysis using a high-purity germanium detector. The results revealed
higher concentrations of 40K compared to 232Th and 238U in the soil samples. Saje samples
revealed mean concentrations of 238U and 40K above their global averages, while those of
232Th were below the global averages. The mean concentrations of 238U, 232Th and 40K were
all above the global averages for Oke-Diya samples. Ita-Oshin and Premier samples
recorded mean concentrations that were below the global averages. The estimated
radiological parameters for the representative soil samples were all below the permissible
limits, except for the absorbed dose rates of Oke-Diya samples. The study areas generally
revealed a reasonably high level of soil radionuclides which may continue to increase with
the dumpsites' age.

Keywords: Dumpsites, Soil, Natural radionuclides, Activity concentrations, Health risks.