Characterization of Petroleum Hydrocarbons in Post-Burn Crude Oil-Spilled Soils, Gokana, Rivers State, Nigeria

Abstract

In the Niger delta, crude oil spilled soils are burned as a means of decontaminating the impacted soils. Gas chromatography - flame ionization detector (GCFID) analyses were performed on oil residues extracted from burnt spilled oil soil samples to facilitate detailed chemical composition and characterization of petroleum hydrocarbons. The concentrations of aliphatic hydrocarbons (AHCs) from C₁₃ to C₃₆ were low and range from 363.4 to 439.6 mg/kg, with hydrocarbons burning ≤ C₁₂ and the monocyclic aromatics – BTEX not detected in all the samples. Polycyclic aromatic hydrocarbon (PAH) concentrations, which ranged from 3236.6 to 4190.0 mg/kg, were significantly high and constituted from 88.26 to 91.25% of total petroleum hydrocarbon compositions in the burnt spilled oil soil samples. Petroleum hydrocarbon distribution profiles for the AHCs and PAHs were similar for all the samples and indicated similar alteration source. The compositions of AHCs were generally low, between 1.13 and 11.18%, while compositions of PAHs varied considerably from 0.17 to 30.50%. The composition of the 5-6 ring PAHs were between 3.94 - 4.65 times more than the 2-4 ring PAHs. From these results, the burning of spilled oil soils extensively degraded the AHCs and volatile low molecular weight aromatic hydrocarbons and generated significant amounts of 5-6 ring PAHs, some of which are carcinogenic.