Investigation of Poly Aromatic Hydrocarbons and Heavy Metals in Soils of Selected Auto Mechanic Workshops in Nimo, Njikoka, Anambra State, Nigeria

Abstract

Auto mechanic workshop activities and disposal of the wastes into open plots, farms and water drains could pose an environmental risk considering the water table in the east region of Nigeria and shallow bore-holes dug to get water for domestic use. This research aimed at investigating the levels of poly aromatic hydrocarbons (PAHs) and heavy metals (Cd, Cr, Hg, Ni, Pb and V) in soils from four (4) auto mobile mechanic workshops namely; Abba Nimo, Ebengwu Nimo, Oye Nimo and Nimo-Owele Nimo and the control soil sample collected 500m away from auto mechanic activity area at Nimo, Anambra state, Nigeria. The soil samples were prepared in the laboratory following standard procedures and analyzed for 16 US EPA priority PAHs using Gas chromatograph-Buck M910 scientific gas chromatography equipped with flame ionization detector. Total PAHs concentrations in soil from all sampling sites were in the range of 0.1097-1.0916mg/mL. In addition, the dispersion of heavy metals in the soils profile were ascertained using Varian AA 240 atomic absorption spectrophotometer (AAS). The mean levels of Cd, V, Cr & Ni in the soils were within world health organization (WHO) permissible limit while Pb and Hg in some sample sites were above WHO permissible limits for agricultural soils. Lead (Pb) was the most significant contaminant, and its degree of contamination was highest (0.305 mg/kg, 0.481 mg/kg, 0.410 mg/kg and 0.431 mg/kg respectively) followed by Hg which was only found in samples A (0.983mg/kg) and B (1.468 mg/kg).The results obtained from both PAHs and heavy metals analysis indicated that automobile repair activities likely exacerbate pollution issues, as evidenced by the presence of some potential harmful chemicals found in the control sample. This calls for future research on risk assessment and soil remediation of the studied areas. Also, government enforcement agencies should ensure an adherence to proper environmental standard by auto mechanic artisans.