Ecological and radiological hazards due to natural radioactivity and heavy metals in soils of some selected mining sites in Nigeria

Abstract

In this study, the radiological and pollution risks associated with mining of minerals in Nigeria were assessed. Soil samples were collected from a total of 30 illegal mining sites, 10 each from gold, coal and tin mining sites. Thirty soil samples were also collected from unpolluted sites around the mine works. The activity concentrations of the natural radionuclides in the samples were determined using a well calibrated Sodium Iodide Na(Tl) detector. The concentration of Pb, Zn, Cu, Mn, Cr, Cd, Ni and As were determined using an energy dispersive X-ray fluorescence (EDXRF) analyses. The results showed elevated levels of the radionuclides and heavy metals in the mining sites compared to the unpolluted soils. The average outdoor annual effective dose (OAED) obtained were lower than the International Commission on Radiological Protection (ICRP) recommended limit of 1 mSv/y. The results of the geo-accumulation index however showed that the soils of the study areas were strongly contaminated with Pb, Cd and As.