Distribution and Sources of Petroleum Hydrocarbons in Recent Sediments of the Imo River, SE Nigeria

TitleDistribution and Sources of Petroleum Hydrocarbons in Recent Sediments of the Imo River, SE Nigeria
Publication TypeJournal Article
Year of Publication2016
AuthorsOyo-Ita IO, Oyo-Ita OE, Dosunmu MI, Dominguez C, Bayona JM, Albaiges J
JournalArchives of Environmental Contamination and Toxicology
Date PublishedFeb
ISBN Number0090-4341
Accession NumberWOS:000372061700017
KeywordsOil and Gas Degradation
AbstractThe distribution of aliphatic and aromatic hydrocarbons in surface sediments of the lower course of the Imo River (Nigeria) was investigated to determine the sources and fate of these compounds. The aliphatic fraction is characterized by a widespread contribution of highly weathered/biodegraded hydrocarbon residues (reflected in the absence of prominent n-alkane peaks coupled with the presence of 17 alpha(H),21 beta(H)-25-norhopane, an indicator of heavy hydrocarbon biodegradation) of Nigerian crude oils (confirmed by the occurrence of 18 alpha(H)-oleanane, a compound characteristic of oils of deltaic origin). The concentrations of polycyclic aromatic hydrocarbons (PAHs) ranging from 48 to 117 ng/g dry weight (dw; Sigma 13PAHs) indicate a moderate pollution, possibly lowered by the sandy lithology and low organic carbon (OC) content of the sediments. Concentrations slightly decrease towards the estuary of the river, probably due to the fact that these stations are affected by tidal flushing of pollutants adsorbed on sediment particles and carried away by occasional storm to the Atlantic Ocean. A number of PAH ratios, including parent/alkylated and isomeric compounds, indicates a predominance of petrogenic sources, with a low contribution of pyrolytic inputs, particularly of fossil fuel combustion. On the basis of OC/ON (>10) and Per/Sigma PAH(penta-)(>10) values, a diagenetic terrigenous OC was proposed as a source of perylene to the river.