Assessment of Heavy Metal Contamination Levels in Topsoil at Selected Auto-workshops in Accra, Ghana

ABSTRACT The research was conducted to assess the levels of contamination of heavy metal in topsoil at auto-workshops in Accra, to determine the anthropogenic and crustal contributions and the human health risk associated with them. Soil samples collected from four selected auto-workshops were analysed using Atomic Absorption Spectrometer. Eleven (11) elements: Co, Fe, Cu, Mn, Cr, As, Hg, Zn, Pb, Ni and Cd were identified in each sample collected from the auto-workshops. Pollution indices; contamination factor (Cf), index of geoaccumulation (Igeo) and pollution load index (PLI), were used to assess the contamination levels. It revealed the extent of contamination at the auto-workshops for most of the elements which ranged from low to considerate contamination. Lead (Pb) recorded the greatest contamination levels at the auto-electrical location. The results from the index of geoaccumulation showed no pollution to highly pollution indicating high variations of pollution levels at different locations. The results of the PLI in almost all locations ranged from moderately to extremely polluted. Noncancer effect of children and adults due to exposure to the topsoil were also estimated with some selected metal elements. The hazard quotient (HQ) evaluation, showed ingestion to be the route of exposure to soil dust that results in a higher risk for heavy metals, followed by dermal contact. The effect due to inhalation of resuspended dust particles through the mouth and nose is relatively low. It was observed that, the auto-workshops are generally polluted with heavy metals and therefore posing ill-health effect to the humans and the environment.