Hydrocarbon Profile of Oil-Spill-Impacted Soils from Ogoni in Rivers State, Nigeria

Abstract

This research examined the total extractable hydrocarbon content comprising of polycyclic aromatic hydrocarbons (PAHs), total petroleum hydrocarbons (TPHs), total hydrogen carbon (THC) and total organic nitrogen (TON) of an oil-spill-impacted site in Ogoni land, Okenta Alode, Eleme local government area, Rivers state, Nigeria. Sediment samples of crude oil hydrocarbon contaminated soils were randomly collected from different points at the study sites. Samples were collected between 0 - 15cm (surface m level) and 15 - 30cm (in-depth level) with soil auger and thereafter bulked to obtain composite sample. Bio remediated soil, obtained at about 200 m away from the contaminated site was also collected making a total of twelve (12) samples, with the coordinates of the locations recorded with a GPS device. The samples collected in sterile non-reactive polythene bags and transported using icepacks to the laboratory for analyses and the sediments stored at 6°C and extracted within 14 days of collection. The result of the study revealed among others that the oil-spill-impacted sites contain high concentration of TPH, as the highest concentration obtained from the different sites was 298.57 mg/kg and the lowest was 100.80 mg/kg. Also, the in-depth samples contain higher concentrations than the surface level samples, while similar results were also observed for PAHs and THC. The THC values for surface level samples are in the order of P3/S/O2 (129.000 mg/kg) > P5/S/O1 (229.300 mg/kg) > P1/S/O1 (232.200 mg/kg) > P4/S/O1 (256.111 mg/kg) > P2/S/O1 (303.100 mg/kg). The PAHs concentration in the sediment were within the acceptable limits and showed trend of DBA > Chr > BbFL > Ind > BaA > BkFL > Pyr > Fl > Flu > Ant > AcPY > Phen > AcP > NaP. There was no non-carcinogenic and carcinogenic risk posed to the populace as a result of PAHs contamination. Thus, the result suggest that these sediments may be contaminated with PAHs, TPH and THC and has reduced TON due to hydrocarbon contamination which may reduce plant growth in the study area. It recommends that these contaminations resulting from hydrocarbons be contained to prevent it from resulting to deleterious health effects to the exposed populace.