Speciation of Heavy Metals Contaminants at Dumpsites by Improved Sequential Fractionation Technique

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Ajiboso, T.O.
Olayinka, K.O.
Alo, B.I.
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Nigerian Environmental Society (NES)
Speciation of trace metal contaminants in soils was investigated by the improved sequential extraction techniques. Soil samples from some metal dumpsites in Lagos were sequentially extracted so that the heavy metals, cadmium, lead, nickel and zinc could be partitioned into five operationally defined chemical fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and residual. The significance of the analytical results depends on the extraction technique utilised. This work reports an improved sequential extraction technique (SET) for the determination of heavy metal forms in polluted soils. Concentrations of the metal contents in the soil ranged from cadmium 0.0-17.0 mg/kg, lead 13.0-16.562 mg/kg, nickel 5.0-140.5 mg/kg and zinc 28.0-18.994 mg/kg. Soil characteristics, pH and cation exchange capacity did not influence the partitioning of the heavy metals in any consistent manner. The highest percentages of nickel and cadmium were found in the residual and Fe/Mn oxide fractions 53.5% and 41% respectively. For lead and zinc, the highest percentages were found in the Fe-Mn oxide fractions, 47.5% and 40.3% respectively. Lead was the only metal significantly associated with the organic fraction.
Staff publications
Speciation , Heavy metals , soil contaminants , Dump sites , sequential extraction techniques , Research Subject Categories::NATURAL SCIENCES::Chemistry
Ajiboso,T.O, Olayinka, K.O and Alo, B.I (2003). Speciation of Heavy Metals Contaminants at Dumpsites by Improved Sequential Fractionation Technique, Journal of Nigerian Environmental Society, Vol.1, 178-186pp.