ASSESSING LEVELS OF HAZARDOUS METALS IN SOIL AND MEDICINAL PLANTS SAMPLES FROM ASAFO, SUAME AND ASANTE-MAMPONG AUTO-MECHANIC WORKSHOPS

Contents of hazardous metals (Pb, As and Cd) were assessed in medicinal plants and soil samples from auto-mechanic workshops and background soils in Suame and Asafo suburbs of Kumasi and Asante-Mampong the administrative capital of Mampong - Municipal, Ghana with Atomic Absorption Spectrophotometer. Geo-accumulation index (Igeo) by Muller was employed to determine the extent of contamination. SAWS was uncontaminated with As (Igeo = - 2.43), “moderately to heavily contaminated” with Pb (Igeo = 2.79) and Cd (Igeo = 2.26). MAWS was uncontaminated with Pb (Igeo = 0.02), Cd (Igeo = 0.69) and As (Igeo = - 1.38). AAWS was “moderately to heavily contaminated” with Pb (Igeo = 2.84) and Cd (Igeo = 1.18) but uncontaminated with As (Igeo = -1.38). The mean concentration range of Pb recorded for medicinal plants samples at SAWS (2.48 - 38.97) μgg-1, AAWS (1.64-18.16) μgg-1 and MAWS (5.92-19.24) μgg-1 were above the normal medicinal plant Pb concentration (0.2 μgg-1) but below the critical plant concentration (30-300) μgg-1 with the exception of Terminaliacatappa at SAWS. Mean Cd and As levels recorded at SAWS, AAWS and MAWS were within the normal range of medicinal plant Cd and As concentration of (0.1-2.4) μgg-1 and (0.02-7) μgg-1 respectively.The analysis of transfer factor, which was calculated as the ratio of hazardous metal concentrations in medicinal plant to those in the corresponding soil, indicated the uptake capabilities of hazardous metals from soil to medicinal plant.The highest transfer ratios of Pb (0.38 ? 33.58) was recorded at MAWS while As (0.25-2.92) and Cd (0.95-4.07) was measured at SAWS. (0.25 - 2.92) μgg -1 > MAWS (0.36 - 2.09) μgg -1> ABS (0.08 - 0.75) μgg -1 > MBS (0.14 - 0.66) μgg -1 > SBS (0.01 - 0.43) μgg -1 > SBS (0.2 - 0.34) μgg -1.