Application of a new fractionation scheme for heavy metals in soils

A new sequential fractionation procedure was developed to minimise the problems of: (i) the dissolution of manganese (Mn) oxides by H2O2 and NaOAc-HOAc at low pH, and (ii) the release of specifically adsorbed cations by NaOAc-HOAc buffer used for carbonate extraction. The procedure was found to be satisfactory in calcareous soils. Manganese was found mainly in the easily reducible Mn fraction. Most copper (Cu) was found in the residual fraction, but some Cu was also associated with iron (Fe) and aluminum (Al) oxides and easily reducible Mn oxides. The concentration of residual zinc (Zn) was predominantly high in all soils but the proportion of total Zn in the residual fraction decreased with pollution since the additional. Zn goes into the more reactive fractions. The concentrations of Mn, Cu and Zn in soil components were found to be in the following order: Mn oxides > Fe oxides > organic matter > CaCO3. The association of Cu with Fe (Al) oxides, organic matter and easily reducible Mn oxides was higher than that of Zn.