Seasonal Chemical Fractionation of Metals in Some Dumpsites Soils in Zaria Metropolis, Nigeria

Abstract

The study was aimed at investigating the chemical fractionation, bioaccumulation and bioavailability of Hg, Cd, Cu, Pb and Zn in the refuse waste soils of some dumpsites across the seasons (wet and dry) in Zaria metropolis. The heavy metals in the waste soils were sequentially extracted and measured using atomic absorption spectrophotometry. The results revealed that high concentrations of metal in dry season. The non-residual fraction was found to be the most abundant pools for all the metals across the seasons (wet and dry). Also, significant amounts of Hg, Cd and Cu were mostly found in the bioavailable fractions across the sites in the seasons. Thus, these metals would readily be bioavailable to the environment. Overall, the order of mobility and bioavailability of these metals across the seasons (dry and wet) followed the pattern; Hg > Cd > Pb > Zn > Cu and Hg > Cd > Cu > Zn > Pb respectively. Tendencies of health risk for human and livestock due to the spread of the metal pollution from waste dumpsites to agricultural areas is high. Bioaccumulation of cadmium and mercury cause liver, brain and intestinal disorders, irreversible damage to nervous system and brain, protoplasmic poisoning etc.

Keywords: Metals, Bioavailability, Dumpsites, Human Toxicity, Soil.