Lise Sigouin

Comparison of oil composition changes due to biodegradation and physical weathering in different oils

The well-characterized Alberta Sweet Mixed Blend oil and several other oils which are commonly transported in Canada were physically weathered and then incubated with a defined microbial inoculum. The purpose was to produce quantitative data on oil components and component groups which are more susceptible or resistant to biodegradation, and to determine how oils rank in relation to each other in terms of biodegradation potential. The biodegraded oils were characterized by quantitative determination of changes in important hydrocarbon groups including the total petroleum hydrocarbons, total saturates and aromatics, and also by quantitation of more than 100 individual target aliphatic, aromatic and biomarker components. The study reveals a pattern of distinct oil composition changes due to biodegradation, which is significantly different from the pattern due to physical or short-term weathering. It is important to be able to distinguish between these two forms of loss, so that loss due to weathering is not interpreted as loss due to biodegradation in the laboratory or in the field. Based on these findings, the oil composition changes due to biodegradation can be readily differentiated from those due to physical weathering. To rank the tested oils with respect to biodegradability, losses in total petroleum hydrocarbons and aromatics were used to calculate biodegradation potential indices, employing equations proposed by Environment Canada and the US National Oceanic and Atmospheric Administration. The different methods produced very similar biodegradation trends, confirming that patterns of oil biodegradability do exist.

Characterization and source identification of hydrocarbons in water samples using multiple analytical techniques.

This paper describes a case study in which multiple analytical techniques were used to identify and characterize trace petroleum-related hydrocarbons and other volatile organic compounds in groundwater samples collected in a bedrock aquifer exploited for drinking water purposes. The objective of the study was to confirm the presence of gasoline and other petroleum products or other volatile organic pollutants in those samples in order to assess the respective implication of each of the potentially responsible parties to the contamination of the aquifer. In addition, the degree of contamination at different depths in the aquifer was also of interest. The analytical techniques used for analyses of water samples included gas chromatography-mass spectrometry (GC-MS) and capillary GC with flame-ionization detection, solid-phase microextraction and headspace GC-MS techniques. Chemical characterization results revealed the following: (1) The hydrocarbons in sample A (near-surface groundwater, 0-5 m) were clearly of two types, one being gasoline and the other a heavy petroleum product. The significant distribution of five target petroleum-characteristic alkylkated polycyclic aromatic hydrocarbon homologues and biomarkers confirmed the presence of another heavy petroleum product. The concentrations of the TPHs (total petroleum hydrocarbons) and BTEX (collective name of benzene, toluene, ethylbenzene, and p-, m-, and o-xylenes) were determined to be 1070 and 155 microg/kg of water for sample A, respectively. (2) The deepest groundwater (sample B, collected at a depth ranging between 15 and 60 m) was also contaminated, but to a much lesser degree. The concentrations of the TPH and BTEX were determined to be only 130 and 2.6 microg/kg of water for sample B, respectively. (3) The presence of a variety of volatile chlorinated compounds to the groundwater was also clearly identified.

Using systematic and comparative analytical data to identify the source of an unknown oil on contaminated birds

Abstract A tiered and integrated analytical approach for identification of the source of an unknown oil on contaminated birds by use of systematic and comparative GC–MS and GC–flame ionization detection data is described. Characterization of the unknown oil was achieved through a variety of “standard” analyses including not only individual aliphatic, aromatic and biomarker hydrocarbon analysis, but also “source-specific-marker” diagnostic ratio analysis. Once precise chemical data were obtained and data analysis and comparison with the corresponding data from the known oils was completed, product identification (fingerprinting) techniques were used to identify the type of product present, and to estimate the degree of weathering the product had undergone since release. It was concluded that: (1) the residual oil on the birds was most probably an old Bunker C type oil and not from the suspected barge oil; (2) the oil on contaminated birds was relatively highly weathered and (3) some biodegradation of the oil had occurred.

Identification and Linkage of Tarballs from the Coasts of Vancouver Island and Northern California Using GC/MS and Isotopic Techniques

During January and February 1996, a significant number of tarball/patty incidents occurred along the coasts of Vancouver Island, Washington, Oregon, and California. Samples of the tarballs were collected from the affected beaches and analyzed by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/flame ionization detector (GC/FID) using a tiered analytical approach developed for determining the origin of oils. Selected samples were further analyzed using a carbon isotopic technique. Also, the relative abundances of a large number of “source-specific marker” compounds, in particular alkylated series of polycyclic aromatic hydrocarbons within the same alkylation isomeric groups, were compared. Results of the analysis revealed that (1) California/Oregon samples were chemically similar and consistent with the same source. They were identified to be bunker type fuel; (2) The tarball samples collected from British Columbia and Ocean Shores, Washington were chemically similar and consistent with the same source (also bunker type fuel). They were found to be similar to but may have a source different than the California/Oregon samples; (3) The source of the tarball/patty samples was neither Alaska North Slope oil nor California Monterrey Miocene oil; (4) The spilled oil samples have been highly weathered since release, and the California samples were more heavily weathered than the British Columbia samples.

A new method for the determination of wax content of crude oils

Abstract A new method has been developed for determining the wax content in crude oils. Saturate fractions, obtained during hydrocarbon group separations by open column chromatography, were analyzed by gas chromatography with flame ionization detection (GC/FID). The ratio of the resolved C 18 + area to the total area was used to calculate the wax content of the oil. Using both the new method and the conventional method (gravimetric determination of solvent-precipitated waxes) 25 crude oils were analyzed. Overall, very good agreement was found between the two methods. One solvent-precipitated wax sample was subjected to a clean-up procedure and n -alkane distributions were obtained for the ‘clean’ and ‘dirty’ waxes. Co-precipitation of polar compounds and entrapment of oil during wax crystallization can cause the gravimetric wax contents of some oils to be exaggerated. It is suggested that the most problematic oils are those that exhibit non-Newtonian flow behaviour at 15°C.

PAH Distribution in the 1994 and 1997 Mobile Burn Products and Determination of the Diesel PAH Destruction Efficiencies

ABSTRACT In 1994 and 1997, several U.S. and Canadian government agencies jointly conducted a series of mesoscale burns in Mobile Bay, Alabama, to study various aspects of in situ diesel fuel burnin...

Fate and Persistence of Long-Term Spilled Metula Oil in the Marine Salt Marsh Environment: Degradation of Petroleum Biomarkers

ABSTRACT Complete “total oil analyses” were performed on the 24-year-old spilled Metula oil samples collected during the 1998 field visit. Fingerprinting data clearly indicate, except those three samples collected from the East Marsh untreated plots (EE-GO, EE-CI and EE-C2) that were only moderately weathered, the spilled oil has undergone significant alteration in chemical composition after 24 years. There are no fundamental differences between heavily weathered and degraded West Marsh and treated East Marsh samples. However, the effect of the experimental tilling action has been to promote plant recolonization. This result indicates that the recolonization of the marshes almost certain would have been accelerated had tilling or mixing been conducted on these sites after the spill. Chemical analyses of the two asphalt pavement samples (WI-1 and WI-2) indicate extremely heavy degradation. For these two samples, complete spectrum of n-alkanes from C8 to C40 and greater than 98% of alkylated PAH homologues ...

Development In Fingerprinting Analysis of Petroleum Hydrocarbons

ABSTRACT Major advances have been made on analyses of petroleum hydrocarbons in oils, petroleum products and complex oil-spill-related environmental samples. This paper briefly describes how the ad...