DETERMINATION OF HEAVY METALS AND POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN SELECTED MOTOR VEHICLE MECHANIC WORKSHOPS WITHIN ILESA TOWN, NIGERIA

Abstract

This study was carried out to determine the physicochemical properties, 10 selected heavy metals (Pb, Fe Cu, Cr, Co, Ni, Zn, Ca, Mg) and Polycyclic Aromatic Hydrocarbons (PAHs) of the surface soil (0-15) and well water at some selected auto mechanic village within Ilesa West Local Government area of Osun State. This was with a view to establishing the pollution status of the studied surface soil and ground water with heavy metals and PAHs and its safety for drinking. Water and soil samples were collated between December 2018 and February 2019 from three (3) selected auto mechanic village namely Ayeso, Isida and Iroye . Water sample was taken from hang –dug wells around the mechanic workshop and a control sites where there is no influence of mechanic activities. Physicochemical properties of soil and water were determine to evaluate the quality of soil and drinking water while the PAHs in the water samples were extracted with n-hexane using soxhelet extraction method. The qualitative identification and quantitative estimation for PAHs and heavy metals were carried out with the use of Gas chromatography – Mass Spectrometry and Atomic Absorptn Spectroscopy (AAS) respectively .The physicochemical parameter such a pH, Total Alkalinity, Sulphate Ions, Nitrate ions Phosphate ions, and chemical oxygen demand were above the limits stipulated by the regulatory bodies (WHO and SON) for drinking water. Also, the concentration of heavy metals ( Pb, Fe, Cu, Cr, Co, Ni, Zn, Ca, Mg) obtained in most of the studied location were above recommended limit /expect for As that is below the permissible limits. Similarly, the PAHs Recorded include : Naphthalene, Fluorene, Phenathrene, Pyrene, Acenaphthalene, Beno[c]phenathrene, Benz[a]anthracene, Chrysene, Benzo[k]fluoranthene, Benzo[b+j] fluoranthene, indeno[1,2,3]pyrene, Dibenzo[a, i]pyrene, 3-Methylchloranthrene, Dibenzo[a, h], Benzo[ghi]perylene, Dibenzo[a,l]pyrene, benzo[e]pyrene, Benzo[a]pyrene, The value of PAHs obtained in this study were mostly above the 0.005 mg L-1 of WHO threshold limits. Continuous use of the water from the studied area by the people of the community over a period of time may cause disorderliness of the body system functionality, be at risk of cancer diseases, and low intelligence quotient in children.