Source identification of an unknown spilled oil from Quebec (1998) by unique biomarkers and diagnostic ratios of "source-specific marker" compounds

This paper describes a case study in which forensic chemical analyses were conducted to determine the liability for the release of an unknown petroleum product into a river. On June 29th 1998, a fire broke out at a carpet factory in Acton Vale, Quebec. Two months after the fire, there were reports of significant amounts of oil on the surface of the river near the factory. The source of the spilled oil was identified by the standard comparison of the chemical fingerprints of aliphatic, aromatic, biomarker, and total petroleum hydrocarbon fractions, and was further confirmed by determining and comparing the diagnostic ratios of a series of "source-specific marker" compounds, in particular isomers of polycyclic aromatic hydrocarbons (PAHs) and alkylated series of PAHs within the same alkylation groups. Furthermore, an unusually high abundance of the biomarker compound C-30 beta alpha hopane was found in both the suspected source and spill samples. This unique feature is rarely seen in crude oils and refined products. Stable carbon isotopic ratio analyses were also performed. From the chemical fingerprinting and data interpretation results we conclude that (1) the residual oil in the spill samples was a Bunker C type fuel; (2) the oil in the samples collected from the river and from a retention basin in the factory all matched with the oil in the heat exchange equipment near the boner; (3) the oil collected from the river had been heavily weathered; (4) biodegradation of the oil was evident for the river on-water samples.