Content of Heavy Metal in Samples Collected from Waste Dumpsites

Total Concentrations of heavy metals (Pb, Cr, Zn, Cd, Mn and Cu) were investigated in soils, Eleusine indica and Lumbricus terrestris from selected solid waste dumpsites of Kano and Kaduna metropolitan cities, Nigeria. The chemical mobility and potential phytoavailability of the metals were also determined in the soils using a six-step sequential extraction procedure. Physicochemical properties of the soils were also assessed using standard procedures. Flame Atomic Absorption Spectrophotometer was used for the chemical analysis of the test sample extracted. The results of the total metal concentrations in the test samples were higher at the dumpsites (p<0.05) than the control areas. The trend in metal abundance at both the dumpsite and control areas: Soils>Plants>Earthworms. The levels of Pb, Cd, Cr and Cu in most of the dumpsites exceeded the CCME threshold limits for agricultural soils. The concentrations of the mobilized fractions indicated that about 50% to 60% of the metals were in the residual phase suggesting that the pollutants were more in the inert form and may pose no immediate threat to the environment and man.