Chemical fractionation of some heavy metals in soil profiles in vicinity of scrap dumps in Warri, Nigeria

摘要

The lability of Cr, Ni, Pb, Fe, Mn, Cd and Cu in soils contaminated by scrap dumps in Warri, Nigeria was assessed by a sequential chemical extraction procedure (SCE) to fractionate the metals into MgCl2 extractable fraction, Na-acetate extractable fraction, hydroxylamine hydrochloride extractable fraction, HNO3/H2O2 extractable fraction and HF/aqua-regia extractable fraction. The results indicate that Pb is associated with HF/aqua-regia and hydroxylamine hydrochloride extracted fraction. Copper and chromium was associated with HNO3/H2O2 and HF/aqua-regia extracted fractions. Cd, Mn and Fe were associated with HF/aqua-regia and hydroxylamine hydrochloride extracted fractions. However, in some sites up to 45% of Cd was found in the MgCl2 and Na-acetate extracted fractions. The metals associated with hydroxylamine hydrochloride and HNO3/H2O2 extractable fractions may be available to the biota when the pH and the redox potential of the soil changes. Data presented provides information on the lability of metals in soil profiles in the vicinity of scrap dumps.