Assessment of heavy metal contamination in soils at the Kpone landfill site, Ghana: Implication for ecological and health risk assessment

Concentrations of lead (Pb), zinc (Zn), copper (Cu), mercury (Hg), and arsenic (As) in soils at the Kpone landfill site (Ghana) were determined using Atomic Absorption Spectrophotometry (AAS). Further analyses allowed establishing the degree of heavy metals (HMs) pollution, suitability of the soils for agriculture, sources of the HMs and their ecological and health risks. The site was divided into five zones, A, B, C, D, and E, and in all, seventeen (17) soil samples were collected. Average concentrations of Cu fell within the allowable range for agricultural soils in all the zones while average concentrations of Pb, Zn, Hg, and As exceeded the range in some or all the zones. Concentrations of the HMs generally exceeded their respective background value, with all zones showing very high degree of HMs contamination. The pollution load index (PLI) was 16.48, signifying extreme HMs pollution of the entire site. Multivariate statistical analyses revealed that Cu, Zn, and Pb in the soils originated from the deposited waste materials as well as traffic-related activities (e.g. wear and tear of tyres, brakes, and engines) at the site. Hg also originated from the deposited waste materials as well as cement production and oil and coal combustion activities in the study area, while As derived from industrial discharges and metal smelting activities. All the zones exhibited very high ecological risk. The carcinogenic and non-carcinogenic health risks posed by the HMs were also above acceptable levels, with children being more vulnerable than adults to these health risks.