International Research Journal of Pure and Applied Chemistry

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 previously 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 (BeCl₂, mixture of BeCl₂/BaCl₂ and CaCl₂/NH₄Cl), revealed that these reagents could be used for the leaching of the exchangeable fraction in speciation analysis. BeCl₂ extracted 0.6499 mg/kg of the exchangeable Cd while the conventional MgCl₂ extract 0.010 mg/kg (Cd). The results also revealed that the mixture BeCl₂/BaCl₂ extracted 0.4384 mg/kg of Cd. The use of the mixture of BeCl₂/BaCl₂ and CaCl₂/NH₄Cl extractants leached exchangeable Ni more than the conventional single extractants. BeCl_2, NH₄Cl and the mixture of BeCl₂/BaCl₂, reagents were better extractants for the exchangeable Mn in soil samples.