Bruce P. Hollebone

Comparative toxicity of four chemically dispersed and undispersed crude oils to rainbow trout embryos.

The chronic toxicity of crude oil to fish embryos depends on the chemical constituents of the test oil and on factors that control the exposure of embryos to those constituents. The partitioning of chemicals from oil to water depends on the surface area of oil exposed to water and thus on the susceptibility of oil to be dispersed into droplets. The chronic toxicity of four different crude oils to embryos of rainbow trout (Oncorhynchus mykiss) was measured by exposure to the water-accommodated fraction (WAF; no droplet formation) and to the chemically enhanced WAF (CEWAF) of each oil. When effects were compared with the amount of WAF or CEWAF added to test solutions, chemical dispersion increased toxicity dramatically, by >35 to >300-fold, with the smallest difference measured for the lightest and least viscous oil. When effects were compared with measured concentrations of oil in test solutions, there were no differences in toxicity between WAF and CEWAF treatments, indicating that chemical dispersion promoted droplet formation and the partitioning of hydrocarbons from oil to water. On a dilution basis, the differences in toxicity among the four oils were correlated with the concentrations in oil of polynuclear aromatic hydrocarbons (PAH), particularly those with three to five rings, and with their viscosity, an index of dispersibility. However, when PAH concentrations were measured in solution, toxicity did not vary substantially among the four oils, suggesting that the PAH of each oil had equivalent toxicities and that differences in toxicity represented differences in dispersability.

Chemical Fingerprints of Alberta Oil Sands and Related Petroleum Products

Alberta oil sands are known to contain the worlds largest reserves of bitumen. The rapid growth in their production could result in a significant environmental impact. Fingerprinting bitumen and petroleum products from the Alberta oil sands is essential in order to better understand the chemical compositions of oil sands, prepare for potential oil spills, and address the associated environmental problems. This study presents an integrated quantitative chemical characterization of Alberta oil sands bitumen and other related Alberta oils using gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The characterized target hydrocarbons include n-alkanes, unsubstituted polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues (APAHs), biomarker terpanes and steranes, bicyclic sesquiterpanes, and diamondoids. The chemical features of bitumen in oil sands are clearly distinguishable from those of most other conventional crude oils. The chemical fingerprints of diluted oil sands bitumen and Albian Heavy Synthetic crude were significantly altered by either the diluent blended with the former or the upgrading processing of crude bitumen in the latter. A chromatographic hump of unresolved complex mixtures (UCMs) eluting between n-C10 to n-C40 is pronounced and n-alkanes are nearly absent in bitumen extracted from oil sands. Alkylated naphthalenes account for only a small proportion of the total APAHs in Alberta oil sands extracts. The PAH compounds in oil sands extracts and diluted bitumen are dominated by alkylated homologues with the relative distribution of C0– < C1– < C2– < C3– for all five APAH series. Biomarker terpanes and cage-like adamantanes were determined in almost identical abundance and distribution profile in oil sands extracts and diluted crude bitumen, while biomarker steranes and bicyclic sesquiterpanes were removed to varying degrees by physical weathering or biodegradation.

Petroleum biomarker fingerprinting for oil spill characterization and source identification

Biological markers, or biomarkers, are one of the most important hydrocarbon groups in petroleum used for chemical fingerprinting. Biomarkers can be detected in low quantities (ppm and sub-ppm level) in the presence of a wide variety of other types of petroleum hydrocarbons by the use of the gas chromatography–mass spectrometry (GC–MS). Relative to other hydrocarbon groups such as alkanes and most aromatic compounds, biomarkers are highly resistant to degradation in the environment. The chapter provides analytical methodologies for petroleum biomarker fingerprinting, which include: petroleum biomarker families and labeling and nomenclature of biomarkers. The benchtop quadrupole GC–MS systems, although lacking the high-resolution capabilities of larger and more expensive magnetic-sector instruments, have sufficient sensitivity and selectivity for most purposes of biomarker analysis. In addition to petroleum biomarkers, oil-contaminated sediment samples may contain modern plant biomarker compounds. Chemical fingerprinting of source characteristic and environmentally persistent biomarkers generates information of great importance to environmental forensic investigations in terms of determining the source of spilled oil, differentiating and correlating oils, and monitoring the degradation process and weathering state of oils under a wide variety of conditions.

Characteristics of bicyclic sesquiterpanes in crude oils and petroleum products

This study presents a quantitative gas chromatography-mass spectrometry analysis of bicyclic sesquiterpanes (BSs) in numerous crude oils and refined petroleum products including light and mid-range distillate fuels, residual fuels, and lubricating oils collected from various sources. Ten commonly recognized bicyclic sesquiterpanes were determined in all the studied crude oils and diesel range fuels with principal dominance of BS3 (C(15)H(28)), BS5 (C(15)H(28)) and BS10 (C(16)H(30)), while they were generally not detected or in trace in light fuel oils like gasoline and kerosene and most lubricating oils. Laboratory distillation of crude oils demonstrated that sesquiterpanes were highly enriched in the medium distillation fractions of approximately 180 to 481 degrees C and were generally absent or very low in the light distillation fraction (boiling point to approximately 180 degrees C) and the heavy residual fraction (>481 degrees C). The effect of evaporative weathering on a series of diagnostic ratios of sesquiterpanes, n-alkanes, and biomarkers was evaluated with two suites of weathered oil samples. The change of abundance of sesquiterpanes was used to determine the extent of weathering of artificially evaporated crude oils and diesel. In addition to the pentacyclic biomarker C(29) and C(30) alphabeta-hopane, C(15) and C(16) sesquiterpanes might be alternative internal marker compounds to provide a direct way to estimate the depletion of oils, particularly diesels, in oil spill investigations. These findings may offer potential applications for both oil identification and oil-source correlation in cases where the tri- to pentacyclic biomarkers are absent due to refining or environmental weathering of oils.

GC/MS Quantitation of Diamondoid Compounds in Crude Oils and Petroleum Products

This study presents a quantitative gas chromotography/mass spectrometry (GC/MS) method for the analysis of adamantane, diamantane, and their alkylated homologues in 14 crude oils and 22 petroleum products including light and mid-range distillate fuels, residual fuels, and lubricating oils collected from various sources. The method detection limits for five target diamondoids were in the range of 0.06 to 0.14 μ g/g oil. The total concentration of adamantane and its 16 alkylated homologues commonly range from approximately 40 to 500 μ g/g in most crude oils and from 0.6 to 1,300 μ g/g in refined products, but reaching values of up to 2,000 μ g/g for the south Louisiana crude oil and the Jet A fuel. Diamantanes occur in all crude oils and lighter to middle distillates, and their total concentration was in a range of 5 to 200 μ g/g and with maximum values near 600 μ g/g in weathered diesel fuel, but they were not detected in very light distillates and most lubricating oils. Laboratory distillation of crude oils demonstrated that adamantane series were highly enriched in the diesel distillation range between 180 to 287°C, while diamantanes were largely found in the distillation fraction from 280 to 320°C. The concentrations of five groups of biomarker compounds in the saturated hydrocarbon fraction decrease in the order of sesquiterpanes > terpanes ≥ steranes > adamantanes > diamantanes for most crude oils, while their concentrations in various refined products differ widely. The absolute concentrations of diamondoid compounds and their molecular indices offer potential diagnostic means for oil source identification and oil correlation, particularly for lighter refined products such as jet and diesel fuels in which the high molecular weight biomarkers have been removed during the refining processes.

Identification of compounds in heavy fuel oil that are chronically toxic to rainbow trout embryos by effects‐driven chemical fractionation

The present study isolated and identified compounds in heavy fuel oil 7102 (HFO 7102) that are bioavailable and chronically toxic to rainbow trout embryos (Oncorhynchus mykiss). An effects-driven chemical fractionation combined the chemical separation of oil with toxicity testing and chemical analyses of each fraction to identify the major classes of compounds associated with embryo toxicity. Toxicity was assessed with 2 exposure methods, a high-energy chemical dispersion of oil in water, which included oil droplets in test solutions, and water accommodated fractions which were produced by oiled gravel desorption columns, and which did not contain visible oil droplets. Fractions of HFO with high concentrations of naphthalenes, alkanes, asphaltenes, and resins were nontoxic to embryos over the range of concentrations tested. In contrast, fractions enriched with 3- to 4-ringed alkyl polycyclic aromatic hydrocarbons (PAHs) were embryotoxic, consistent with published studies of crude oils and individual alkyl PAHs. The rank order of fraction toxicity did not vary between the exposure methods and was consistent with their PAH content; fractions with higher-molecular weight alkyl PAHs were the most toxic. Exposure of juvenile trout to most fractions of HFO induced higher activities of cytochrome P450 enzymes, with a rank order of potency that varied with exposure method and differed somewhat from that of embryotoxicity. Induction reflected the bioavailability of PAHs but did not accurately predict embryotoxicity.

Development of a methodology for accurate quantitation of alkylated polycyclic aromatic hydrocarbons in petroleum and oil contaminated environmental samples

Polycyclic aromatic hydrocarbons (PAHs) are compounds of concern because most of these compounds are toxic, carcinogenic, or mutagenic and are relatively persistent in the environment. Reliable quantitative information of PAHs is important to evaluate the acute and chronic harmful effects of PAHs on the ecosystem. Crude oils and refined petroleum products contain many highly abundant PAHs and heterocyclic PAHs, in particular the alkylated homologues of naphthalene, phenanthrene, dibenzothiophene, fluorene and chrysene (APAH). The alkylated PAH homologues usually occur in significantly higher concentrations than their corresponding unsubstituted parent PAHs. Petrogenic alkylated PAHs generally consist of large numbers of isomers. Unlike those individual unsusbstituted PAHs, most of the APAH isomers are not commercially available. Therefore, historically, the target APAHs are generally quantified using the relative response factors (RRFs) obtained from their respective unsubstituted parent PAH compounds, this inevitably results in the quantitative results of APAH being significantly underestimated. In order to improve the accuracy of the measurement of PAHs and their alkylated homologues in oil and oil related samples, this study measured and compared the response factors of a large number of alkylated PAHs relative to the internal standards in gas chromatography-mass spectrometry (GC-MS) analysis, with the goal of developing a more accurate quantitative methodology for the determination of oil APAHs, and eventually leading to a standardized methodology of quantitative APAH analysis. The PAHs in different oils and related environmental samples collected from oil impacted areas were determined using this GC-MS methodology. Furthermore, the influence of the measurement methodology on the diagnostic ratios of target PAHs was also assessed in this work.

Chronic toxicity of heavy fuel oils to fish embryos using multiple exposure scenarios

The chronic toxicity to rainbow trout (Oncorhynchus mykiss) embryos of heavy fuel oil (HFO) 6303, weathered HFO 6303, HFO 7102, and medium South American (MESA) crude oil was assessed by different exposure regimes. These included water accommodated fractions (WAF; water in contact with floating oil), chemically enhanced WAF (CEWAF; oil dispersed with Corexit 9500), and effluent from columns of gravel coated with stranded oil. Heavy fuel oil WAF was nontoxic and did not contain detectable concentrations of hydrocarbons, likely because the high density and viscosity of HFO prevented droplet formation. In contrast, chemically dispersed HFO and effluent from columns of stranded HFO contained measurable concentrations of alkyl polycyclic aromatic hydrocarbons (PAH), coincident with embryo toxicity. These exposure regimes enhanced the surface area of oil in contact with water, facilitating oil-water partitioning of hydrocarbons. Heavy fuel oil was consistently more toxic to fish than crude oil and the rank order of alkyl PAH concentrations in whole oil were sufficient to explain the rank order of toxicity, regardless of exposure method. Thus, the propensity of HFO to sink and strand in spawning shoals creates a long-term risk to developing fish because of the sustained release of PAHs from HFO to interstitial waters. Further, PAH monitoring is key to accurate risk assessment.

Effects-driven chemical fractionation of heavy fuel oil to isolate compounds toxic to trout embryos.

Heavy fuel oil (HFO) spills account for approximately 60% of ship-source oil spills and are up to 50 times more toxic than medium and light crude oils. Heavy fuel oils contain elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) and alkyl-PAHs, known to be toxic to fish; however, little direct characterization of HFO toxicity has been reported. An effects-driven chemical fractionation was conducted on HFO 7102 to separate compounds with similar chemical and physical properties, including toxicity, to isolate the groups of compounds most toxic to trout embryos. After each separation, toxicity tests directed the next phase of fractionation, and gas chromatography-mass spectrometry analysis correlated composition with toxicity, with a focus on PAHs. Low-temperature vacuum distillation permitted the separation of HFO into 3 fractions based on boiling point ranges. The most toxic of these fractions underwent wax precipitation to remove long-chain n-alkanes. The remaining PAH-rich extract was further separated using open column chromatography, which provided distinct fractions that were grouped according to increasing aromatic ring count. The most toxic of these fractions was richest in PAHs and alkyl-PAHs. The results of the present study were consistent with previous crude oil studies that identified PAH-rich fractions as the most toxic.

Assessment of the oxidative stability of lubricant oil using fiber-coupled fluorescence excitation-emission matrix spectroscopy.

The fluorescence of antioxidant additives in lubricant oil was used as an indicator of oxidative stability of the oil. It was found that the decrease in fluorescence intensities of phenyl-α-napthylamine, its dimer, and another unidentified antioxidant coincide with the formation of decomposition products of the oil base stock. Simple kinetic models were developed that were capable of describing antioxidant reactions as a pseudo first-order processes. It is shown that fluorescence excitation emission matrix (EEM) spectroscopy coupled with an optical fiber probe can provide real-time assessment of the oxidative stability of the lubricant. Parallel factor (PARAFAC) analysis was used to correlate the component scores to the oil breakdown number.