Physicochemical analysis of automobile waste oil on soil quality in Benin City, Nigeria

Sustainable use of soil on which agriculture depends is absolutely necessary for agricultural productivity. Soil samples were collected from two auto-mechanic workshops sited at Technical College Road (Station A) and Textile Mill Road (Station B) while the control was at EDPA Housing Estate, all in Benin City with the aid of a split soil core sampler at a depth of 0  10cm. The Physicochemical parameters of the samples were analysed using standard methods and revealed pH mean value of 7.27 at station A and 6.83 at station B respectively. The total petroleum hydrocarbon (THC) had mean value of 61.93 at station A and 66.73 mg kg-1 and these concentrations were relatively high and represent elevated concentrations above background levels found in unpolluted soils. Generally, the concentration of heavy metals in the examined site A and B followed the same order: Fe >Zn > Mn > Pb > Cr > Cd > Ni>V and exceeded the permissible limits of WHO and NESREA. To effectively control issues related to soil contamination with engine oil, it has been suggested that the concept of environmentally friendly automobile mechanic village be established for the disposal or otherwise recycling of used motor engine oil.