Characterisation of Hydrocarbon Pollutants in Soils from Selected Areas in Abraka, Delta State, Nigeria

Abstract

The concentration, distribution and sources of petroleum hydrocarbons in soils from selected areas in Abraka, Delta State, were evaluated. Soil samples were collected from areas suspected to be contaminated with petroleum hydrocarbons, which were also in proximity to human population. These areas included busy junctions, generator maintenance workshops, suya joint, drainage and fuel stations. Samples were extracted using n-hexane/dichloromethane mixture and quantified using gas chromatograph-flame ionization detector. The concentrations of n-alkanes ranged from <0.01 – 10,912 µg kg^-1, while molecular indices showed that the n-alkanes in the soils originated from different anthropogenic sources. For polycyclic aromatic hydrocarbons (PAHs), the ∑17 PAHs in soils ranged from 32 to 162 µg kg^-1. The decreasing order of PAHs followed the order: suya joint > generator maintenance workshops > drainage > fuel station > busy junction, while the occurrence pattern with respect to ring size was of the order: 3-rings > 4-rings > 2-Rings > 5-rings > 6-rings. The lower molecular weight (2-3 rings) and non-carcinogenic PAHs were predominant in the studied soils. The isomeric ratios and principal component analysis indicated that PAHs in these soils originated from high temperature combustion of biomass and fossil fuels, as well as traffic emissions.