Petroleum Contamination of Sombreiro River in Akuku-Toru Local Government Area Rivers State, Nigeria, revealed by Chemical Fingerprinting of Aliphatic Hydrocarbons

Water samples were collected from the lower section of Sombreiro River in Akuku Toru local government area (L.G.A.) of Rivers State, Nigeria and analyzed for aliphatic hydrocarbons using gas chromatographyflame ionization detector (GC-FID) after extraction and clean up. GC identified well resolved aliphatic hydrocarbons from C_9 to C_40 which showed similar bimodal n-alkane distributions and unresolved complex mixtures (UCM). Pristane was observed as the most prominent aliphatic hydrocarbon and dominant over phytane in all the samples. Common aliphatic hydrocarbon diagnostic ratios used for fingerprinting and interpreting chemical data were determined. These include carbon preference index (CPI) from 0.70 to 0.82; Pr/Ph from 1.85 - 2.17; Pr/nC17 from 1.67 - 1.87; Ph/nC18 from 0.94 - 1.07 and cross plot.The results reveal the following: (1) crude oil contamination of the lower section of Sombreiro river in Akuku Toru L.G.A. of Rivers State; (2) the same crude oil spilled in the river; (3) the spilled oil is Niger Delta in origin, derived from mixed marine and terrigenous organic matter deposited in an oxic environment; (4) the spilled oil was slightly degraded, its chemical composition has not undergone significant alteration.