Occurrence and Source Apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in Urban Soil of Udu, Near Warri, Delta State

Abstract

The occurrence and sources of polycyclic aromatic hydrocarbons (PAHs) were assessed in urban soils of Udu, near Warri in Delta State, Nigeria. The PAHs were quantified with gas chromatography equipped with flame ionization detector (GC-FID) after extraction and clean-up of the extracts with n-hexane/dichloromethane. The concentrations of ∑16 PAHs in the urban soils ranged from 269 µg kg^-1 to 853 µg kg^-1. On the average, the occurrence of the individual PAH compounds followed the order: DahA > BghiP > IndP > BbF > BaP > Phen > Ace > BkF > Ant > Flu > Nap > Chry > Flt = Pyr > Acy > BaA while the occurrence pattern of the PAHs with respect to ring size was in the order of 5 rings > 6 rings > 3 rings > 4 rings > 2 rings. The higher molecular weight (4-6 rings) PAHs were the predominant PAHs in these urban soils and accounted for 76% of the total PAHs concentrations. The isomeric ratios used for source apportionment indicate that the PAHs in these urban soils originated majorly from high temperature combustion of petroleum, coal, fossil fuels and biomass such as woods.