Elemental and radioactivity analysis of rocks and soils of some selected sites in southwestern Nigeria

The elemental and radioactivity analyses of rock and soil samples from some selected sites in southwestern Nigeria have been done. Measurements of the elemental compositions and activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K were carried out using nuclear activation analysis technique and gamma spectrometry with high purity germanium detector, respectively. The results obtained provide reference data, allowing observation of possible future changes due to future radiological contamination. The activity concentrations of the natural radionuclides measured in the rocks were higher than those of the soils. The mean concentration of the major and minor elements in the rock and soil samples followed the order Al > Ca > Na > K > Mg > Fe > Ti and Mn > Ba > V > As > Cr > Ni > Zn > Cu, respectively. The radiological hazard and pollution risks associated with the natural radionuclides and heavy metals in the samples were assessed. The results obtained for the annual effective dose equivalent (AEDE), internal hazard, external hazard, and representative gamma indices were lower than their respective maximum permissible limit of 1 mSv y^?1 for AEDE and 1 for internal hazard, external hazard, and representative gamma indices as recommended by the International Commission on Radiological Protection (ICRP). The results of the geo-accumulation index, enrichment factor, and the pollution load index indicate that the soils of the study area are uncontaminated with the heavy metals measured except Ado-Ekiti, Ikere, and Igbara-Odo soils which are moderately contaminated with Arsenic (As).