Application of a multimolecular marker approach to fingerprint petroleum pollution in the marine environment

In an attempt to investigate the suitability of a multibiological marker ap proach for defining the origin of petroleum pollution in marine systems, th e aliphatic hydrocarbon compositions of tar ball samples collected from the beaches of a small island impacted by heavy tar loads were determined by g as chromatography and gas chromatography/mass spectrometry, The tar ball sa mples, as collected, were at low stages of biodegradation and had diverse p hysical appearance. The majority of the samples (as many as 7 of the 10) ap peared to be heavy fuel oils - possibly Bunker C, The GC traces for the oth er three tar balls, however, indicated that they were crude oils probably f rom tanker ballast washings or other nonpoint sources like the oil entering from the adjacent North Mediterranean, The biomarkers of the sterane and h opane series in these samples, however, had remained unaffected by weatheri ng, and their distributions revealed significant differences among the samp les suggesting multiple sources of the tar balls. The tar ball samples coul d be genetically subdivided into four groups on the basis of their biomarke r fingerprints, A marine carbonate or evaporite, hypersaline, anoxic deposi tional environment of the petroleum source rock for Type I residues could b e inferred from the even-carbon-number predominance of n-alkanes, the high relative abundance of gammacerane and the predominance of C-35 relative to C-34 17 alpha(H)-homohopanes. Higher plant contribution and a deltaic envir onment of source rock deposition could be concluded for Type II residues fr om the high concentrations of oleanane and diasteranes. On the other hand, Type III residues possessed geochemical characteristics consistent with a n ormal marine carbonate or evaporite source depositional environment under n ormal saline, reducing conditions, Finally, type IV residues had biomarker signatures intermediate between Types II and III, (C) 1999 Elsevier Science Ltd. All rights reserved.