Levels and Sources of Polycyclic Aromatic Hydrocarbons in Urban Soils of Akure, Nigeria

Abstract

Top soils (0-15 cm) of Shasha market, North Gate motor park, Benin motor park and Ilesha motor park in Akure metropolis, Nigeria was sampled. The aim of the research was to determine the concentration of polycyclic aromatic hydrocarbons (PAHs) in frequently visited urban areas. PAHs were determined by extraction using hexane and dichloromethane in an ultra sonicator with a microprocessor for control of time and temperature. The extract was concentrated and cleaned up using Nitrogen gas. Gas Chromatography-Flame Ionization Detector (GC-FID) was used to analyze for PAHs. The ∑PAHs (summation of PAHs) ranged from 6.184-27.046 µg/kg and 1.511-13.766 µg/kg, ∑Low molecular weight PAHs ranged from 3.237-14.672 µg/kg and 0.279-8.338 µg/kg, ∑High molecular weight PAHs ranged from 2.947-12.374 µg/kg and 0.627-5.428 µg/kg in the samples and controls respectively. Shasha market sample and control has the highest ∑PAHs. Source diagnostic ratio inferred that the PAHs originated mainly from combustion sources and vehicular exhaust. The concentration of polycyclic aromatic hydrocarbons in the site samples were all higher than the control samples. Areas with very high activities had higher concentrations.