The concentrations of major and trace elements in environmental samples had been studied by several authors using either atomic absorption spectrometry (AAS) (Mico et al., 2006 Fagbote and Olanipekun, 2010 Zheng et al., 2010, Ghrefat et al., 2010 Ali and Malik, 2011) or XRF analysis (Kierzek et al., 1999 Boyle, 2000 Baranowski et al., 2002 Zhang et al., 2003 Rauf et al., 2004 Bakraji et al., 2010). Potassium is widely distributed in nature, with concentrations varying from about 0.1% for limestone, through 1% for sandstones to as much as 3.5% for some granite (Eisenbud, 1987 Eisenbud and Gesell, 1997).
The average concentration of uranium in the earth crust has been reported to be in the range of 2–3 ppm, while thorium exists in the range of 8–12 ppm (IAEA, 2003a). The concentrations of all these elements depend on the geology of a local environment as well as other natural and anthropogenic processes. The earth crust contains small amount of uranium, thorium, potassium and other trace and major elements such as Cs, Cd, Pb, Fe, Mg, Mn, etc. The results indicate that Cu, Zn, Ni and Mn have EF < 2 indicating minimal or no enrichment while Pb is moderately enriched in all the locations. To assess the level of contamination and the possible anthropogenic impact in the clay soils, the enrichment factor (EF) and the geoaccumulation index (Igeo) were estimated for some potential hazardous elements. The distribution of the various major and trace elements in all the sampling sites do not follow any systematic trend but vary from point to point. The XRF analysis revealed 4 major elements and 11 minor or trace elements present in the clay samples. The overall mean concentrations of these radionuclides are comparable to values from other locations around the world. The results of this study show that the mean concentrations of uranium ranged from 2.2 ± 1.0 mg/kg to 3.2 ± 1.1 mg/kg, that of thorium ranged from 4.0 ± 0.5 mg/kg to 5.7 ± 1.7 mg/kg, while potasium presented in % by weight ranged from 0.4 ± 0.2 to 1.3 ± 0.3 in all the locations.
Radiochemical and elemental analysis of clay soils collected from different locations within Ekiti State have been performed in this study using gamma and XRF spectrometric measurements.
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