Geochemical and health risk assessment of heavy metals concentration in soils around Oke-Ere mining area in Kogi State, Nigeria

This study examined the levels of some heavy metals in soils of Oke-Ere mining area in Yagba West, Kogi State, Nigeria, aim at ascertaining the degree of pollution, and risk pose to the environment, and human health to the residents in the area. A total of 48 soil samples were analysed by using Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The mean concentrations (mg/kg) were As(1.92), Cd(< 0.004), Co(29.8), Cr(117), Mo(4.00), Ni(51.4), Pb(24.1), Sc(17.8), Sn(21.9), and Zn(85.8). Principal component analysis revealed significant anthropogenic contributions of Sc, Cr, Ni, and As in soils. Geochemical assessment evaluated based on models of geochemical load index (Igeo), enrichment factor (EF), contamination factor (Cf) and pollution load index (PLI), revealed that the soils were highly polluted by Sc, moderately polluted by Sn and non-polluted to slightly polluted by other metals. Enrichment factor shows significant enrichment by Sc, while Cr, Pb, Co, Mo and Sn were moderately enriched. The contamination factor indicated low contamination for most of the studied metals except Cu and Co which recorded considerable contamination. The values of pollution load index PLI > 1, signifies that the mining activities deteriorated soil quality. The total hazard index (HI) of the metals for adult and children, indicates HI < 1 which connotes a non-carcinogenic health risk effect. The cancer risk (CR) value for ingestion and dermal exposure pathways was higher than the permissible limits (1 x 10−6 to 1 × 10−4), which indicated adverse health risk to the local resident. This study suggested adequate attention be directed to detailed risk assessment of heavy metals in the study area.