Heavy Metal Speciation in Some Selected Farms Treated with Urban Solid Waste, in Jos South, Plateau State, Nigeria

Abstract

The speciation of metals in environmental samples is a serious factor in appraising the potential environmental impacts, before their disposal. The six step extraction procedure pre vi ously proposed by Obasi et al. was used with modification to systematically study the speciation of Cd, Cu, Mn, Pb, Zn, Fe and Cr in a farm treated with the dumpsite soils. The speciation study revealed higher distribution of the metals in the residual fractions except Cd which had 70.18% in the exchangeable fraction. The results also showed that there were low tendency of bioavailability and reactivity in the environment. The results of the newly introduced extractants (BeCl 2 , mixture of BeCl 2 /BaCl 2 and CaCl 2 /NH 4 Cl), revealed that these reagents could be used for the leaching of the exchangeable fraction in speciation analysis. BeCl 2 extracted 0.6499 mg/kg of the exchangeable Cd while the conventional MgCl 2 extract 0.010 mg/kg (Cd). The results also reve aled that the mixture BeCl 2 /BaCl 2 extracted 0.4384 mg/kg of Cd. The use of the mixture of BeCl 2 /BaCl 2 and Original Research Article