Spatial distribution, exposure, and health risk assessment of bioavailable forms of heavy metals in surface soils from abandoned landfill sites in Kumasi, Ghana

Abstract

In this study, the modified Community Bureau of Reference (BCR) sequential extraction procedure was used to extract mobile, available and persistence forms of heavy metal in soils from the Aboabo and Santasi abandoned landfills sites in Kumasi, Ghana and their concentrations were measured with the AAS. Average daily intakes of heavy metals via oral, inhalation, and dermal exposures were calculated for children. The results showed that all the metals, except Cr, were found to be predominantly associated with the residual forms of soils from the two sites. Bioavailable concentrations of metals in the soils were significant and could pose risk to humans. Children at the Aboabo abandoned landfill site are susceptible to non-carcinogenic effects of Fe, Pb, and Cr, while the Santasi site showed non-carcinogenic implications on children by Fe and Pb. Hazard quotients from the heavy metals indicate that ingestion constitutes the major exposure route. Geochemical distribution maps developed from the bioavailable concentrations of the heavy metals displayed hotspots for Fe, Pb, Cu, Cr, and Co at the Santasi site. Likewise, Co, Zn, Cr, and Cu displayed hotspots at the Aboabo site. Hotspots in the geochemical maps were used as markers of areas with high pollution.