Abstract

The removal of large quantities of overburden through mining has resulted in the pollution of various ecosystems. Soil pollution around the Itakpe mine in Kogi State, Nigeria was studied through the determination of heavy metal concentration and chemical speciation of the metals cadmium (Cd), copper (Cu), magnesium (Mg), nickel (Ni), lead (Pb) and zinc (Zn) in soil using Flame Atomic Absorption Spectroscopy. Soil digestion was done with hydrofluoric-perchloric (HF-HClO₄) acid mixture (5:1) and sequential extraction was carried out with different reagents in the extraction steps; Exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and residual. Mean metal content of mining site soil is 0.16±0.02, 0.15±0.03, 0.04±0.02, 0.11±0.02, 0.07±0.01 and 0.04±0.03mg/g for Cd, Cu, Mg, Ni, Pb and Zn, respectively. Results of sequential extraction of the mining site soil show that the highest metallic levels were observed in the Fe-Mn, organic and residual fractions.

Key words: Mine, heavy metals, tailings, pollution, agricultural soil.