Chemical Weathering Patterns of Diluted Bitumen Spilled into Freshwater Limnocorrals.

Due to the sudden nature of oil spills, few controlled studies have documented how oil weathers immediately following accidental release into a natural lake environment. Here, we evaluated the weathering patterns of Cold Lake Winter Blend, a diluted bitumen (dilbit) product, by performing a series of controlled spills into limnocorrals installed in a freshwater lake in Northern Ontario, Canada. Using a regression-based design, we added seven different dilbit volumes, ranging from 1.5 to 180 L, resulting in oil-to-water ratios between 1:71,000 (v/v) and 1:500 (v/v). We monitored changes in the composition of various petroleum hydrocarbons (PHCs), including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and oil biomarkers in dilbit over time, as it naturally weathered for 70 days. Depletion rate constants (kD) of n-alkanes and PAHs ranged from 0.0009 to 0.41 d-1 and 0.0008 to 0.38 d-1, respectively. There was no significant relationship between kD and spill volume, suggesting that spill size did not influence the depletion of petroleum hydrocarbons from the slick. Diagnostic ratios calculated from concentrations of n-alkanes, isoprenoids, and PAHs indicated that evaporation and photooxidation were major processes contributing to dilbit weathering, whereas dissolution and biodegradation were less important. These results demonstrate the usefulness of large scale field studies carried out under realistic environmental conditions to elucidate the role of different weathering processes following a dilbit spill.

Characterization of Nitrogen-Containing Polycyclic Aromatic Heterocycles in Crude Oils and Refined Petroleum Products.

A large amount of polycyclic aromatic hydrocarbons (PAHs) and their heterocyclic analogues (N, S, O) are released to the marine environment from natural oil seeps, oil spills, bilge discharges and input of land-based sources. Many of these compounds are toxic and have a deleterious effect on marine biota. Nitrogen-containing compounds in crude oils are typically present as cyclic compounds such as polycyclic aromatic nitrogen heterocycles (PANHs) and are generally classified into the two categories of nonbasic (N-PANHs) and basic compounds (B-PANHs). Chromatographic analyses of PANHs are easily to be interfered by other oil components without proper sample preparation prior to instrumental analysis. In this work, dual solid phase extraction columns of 3-(isocyanato)propyl-functionalized silica gel (Si-NCO) and silica gel were employed to efficiently separate both N-PANHs and B-PANHs from saturated and aromatic petroleum hydrocarbons, which enable simultaneous accurate analyses of these groups with single sample preparation. Crude oils studied contain various concentrations of N-PANHs including carbazole, benzocarbazole and B-PANHs including quinolone, acridine and benzoacridine as well as their alkylated homologues. These compounds in light fuel and lubricating oil are generally not detected or are only in trace concentration, but have considerable abundance in heavy fuel oils. Crude oils from different sources and various petroleum products have their unique absolute concentrations and relative distribution patterns of PANHs. Chemical fingerprints of PANHs can provide valuable information for forensic oil spill identification and improve the understanding of the fate, behaviour and chemical degradation of spilled crude oil.

Forensic identification of spilled biodiesel and its blends with petroleum oil based on fingerprinting information.

A case study is presented for the forensic identification of several spilled biodiesels and its blends with petroleum oil using integrated forensic oil fingerprinting techniques. The integrated fingerprinting techniques combined SPE with GC/MS for obtaining individual petroleum hydrocarbons (aliphatic hydrocarbons, polyaromatic hydrocarbons and their alkylated derivatives and biomarkers), and biodiesel hydrocarbons (fatty acid methyl esters, free fatty acids, glycerol, monoacylglycerides, and free sterols). HPLC equipped with evaporative scattering laser detector was also used for identifying the compounds that conventional GC/MS could not finish. The three environmental samples (E1, E2, and E3) and one suspected source sample (S2) were dominant with vegetable oil with high acid values and low concentration of fatty acid methyl ester. The suspected source sample S2 was responsible for the three spilled samples although E1 was slightly contaminated by petroleum oil with light hydrocarbons. The suspected source sample S1 exhibited with the high content of glycerol, low content of glycerides, and high polarity, indicating its difference from the other samples. These samples may be the separated byproducts in producing biodiesel. Canola oil source is the most possible feedstock for the three environmental samples and the suspected source sample S2.

The fate and behavior of petroleum biomarkers in diluted bitumen and conventional crude oil exposed to natural sunlight in simulated seawater.

Given that the physicochemical properties of diluted bitumen (dilbit) can differ from those of conventional crude oil, understanding the fate and behavior of this petroleum product in the environment becomes vital. This study involves the analysis of the photolytic behavior of some representative petroleum biomarkers, bicyclic sesquiterpanes (BSs), admantanes (ADs), diamantanes (DAs), and mono- and triaromatic steranes (MASs and TASs), by exposing Cold Lake Blend (CLB) and Alberta Sweet Mixed Blend (MSW) to winter and summer insolation after being spilled onto artificial brines. Aromatic steranes in all control samples remained relatively stable, whereas the biomarkers of BSs, ADs, and DAs were less stable. Similar to the exhaustive loss of the C10-C17 alkanes, 91%-99% of BSs, ADs, and DAs were lost after five days of insolation, especially in summer. Both MASs and TASs were lost gradually in most scenarios, although both of them were lost faster in MSW than observed for CLB. The removal of MASs and TASs did not differ significantly from each other, although their loss was less than observed for PAHs having similar number of rings and greater than for the C21-C33n-alkanes. Therefore, photooxidation, not evaporation or biodegradation, was the main factor responsible for oxidizing these aromatic steranes. However, biomarkers of BSs, ADs and DAs were mostly lost through evaporation. Therefore, aromatic steranes have the potential to be utilized to evaluate the photolytic behavior of petroleum hydrocarbons, while BSs, ADs, and DAs should not be used for this purpose.

Recommendations for the advancement of oil-in-water media and source oil characterization in aquatic toxicity test studies.

During toxicity testing, chemical analyses of oil and exposure media samples are needed to allow comparison of results between different tests as well as to assist with identification of the drivers and mechanisms for the toxic effects observed. However, to maximize the ability to compare results between different laboratories and biota, it has long been recognized that guidelines for standard protocols were needed. In 2005, the Chemical Response to Oil Spills: Ecological Effects Research Forum (CROSERF) protocol was developed with existing common analytical methods that described a standard method for reproducible preparation of exposure media as well as recommended specific analytical methods and analyte lists for comparative toxicity testing. At the time, the primary purpose for the data collected was to inform oil spill response and contingency planning. Since then, with improvements in both analytical equipment and methods, the use of toxicity data has expanded to include their integration into fate and effect models that aim to extend the applicability of lab-based study results to make predictions for field system-level impacts. This paper focuses on providing a summary of current chemical analyses for characterization of oil and exposure media used during aquatic toxicity testing and makes recommendations for the minimum analyses needed to allow for interpretation and modeling purposes.

Radio- and stable carbon isotope analysis reveals minimal assimilation of petrogenic carbon into an oligotrophic freshwater food web after experimental spills of diluted bitumen.

Following an oil spill into water, bacteria can biodegrade petroleum hydrocarbons which could lead to petrogenic carbon assimilation by aquatic biota. We used changes in the isotope ratios of radio- (Δ14C) and stable (δ13C) carbon to examine the potential for assimilation of petrogenic carbon into a freshwater food web following experimental spills of diluted bitumen (dilbit) into a boreal lake in northwestern Ontario, Canada. Different volumes (1.5, 2.9, 5.5, 18, 42, 82, and 180 L) of Cold Lake Winter Blend (a heavy crude blend of bitumen and condensate) dilbit were applied to seven 10-m diameter littoral limnocorrals (approximate volume of 100 m3), and two additional limnocorrals had no added dilbit to serve as controls. Particulate organic matter (POM) and periphyton from oil-treated limnocorrals had lower δ13C (up to 3.2‰ and 2.1‰ for POM and periphyton, respectively) than the control at every sampled interval (3, 6 and 10 weeks for POM and 6, 8 and 10 weeks for periphyton). Dissolved organic and inorganic carbon (DOC and DIC, respectively) had lower Δ14C in the oil-treated limnocorrals relative to the control (up to 122‰ and 440‰ lower, respectively). Giant floater mussel (Pyganodon grandis) housed for 25 days in aquaria containing oil-contaminated water from the limnocorrals did not show significant changes in δ13C values of muscle tissue compared to mussels housed in control water. Overall, the changes in δ13C and Δ14C observed indicated small amounts (up to 11% in DIC) of oil carbon incorporation into the food web. The combined δ13C and Δ14C data provide evidence for minimal incorporation of dilbit into the food web of this oligotrophic lake, suggesting that microbial degradation and subsequent incorporation of oil C into the food web may play a relatively small role in the ultimate fate of oil in this type of ecosystem.

Parallel quantitation of salt dioctyl sodium sulfosuccinate (DOSS) and fingerprinting analysis of dispersed oil in aqueous samples.

In many jurisdictions, dispersants are included in contingency plans as a viable countermeasure that can help reduce the overall environmental impact of marine oil spills. When used, it is imperative to monitor the progression of dispersant and oil to assess their environmental fate and behaviour. Amphiphilic salt dioctyl sodium sulfosuccinate (DOSS) is the major effective component of the most commonly available dispersants, such as Corexit® EC9500A. Without proper sample preparation, dispersed oil in water samples could interfere with the accurate analysis of DOSS and easily contaminate the LC-MS system. In this work, solid phase extraction (SPE) weak anion exchange (WAX) cartridges were used to separate oil and DOSS in aqueous samples. DOSS was accurately determined by liquid chromatography coupled with a high resolution Orbitrap mass spectrometer (LC-HRMS). Oil fingerprinting analysis was conducted and total petroleum hydrocarbons (TPHs), polycyclic aromatic hydrocarbons (PAHs), and petroleum biomarkers were determined by gas chromatography-flame ionization detection (GC-FID) and mass spectrometry (GC-MS). This SPE-LC/GC-MS method was used for the analysis of oil-dispersant water samples containing a mixture of Corexit® EC9500A and a selection of crude oils and refined petroleum products. Nearly a 100% DOSS recovery was obtained for various oil-surfactant conditions. Parallel quantitation of oils with dispersants was achieved using this method. A portion of the TPH loss was possibly attributed to oil retained by the SPE column. Chemical fingerprints and diagnostic ratios of target compounds in recovered dispersed oil overall remain unchanged compared with those of all studied oils.

Effects of asphaltenes on the photolytic and toxic behavior of bitumen and conventional oil products on saltwater.

The effects of asphaltenes on the photolytic and toxic behavior of petroleum oil on seawater was investigated by exposing five original oils and their maltenes to solar irradiation for seven days. Polycyclic aromatic hydrocarbons (PAHs) experienced the fastest photo-oxidation, but negligible photolytic loss was observed for most normal alkanes and all the petroleum biomarkers from tri-cyclic to pentyl-cyclic terpanes in the test total oil and maltenes. The removal of most PAHs from some maltenes was greater than the corresponding total oils. Deasphalting process did not affect the characteristics of naphthenic acid fraction components (NAFCs) in all control samples. In all test oils, solar irradiation formed abundant NAFCs, in particular those only containing oxygen as the heteroatoms (Oo species). The formed Oo species were abundant in congeners having highly saturated congeners, and shifted to a lighter carbon number after exposed. Deasphalting process significantly enhanced the formation of Oo species (o from 2 to 4) for all test oils, in particular for the Cold Lake Blend and Bunker C. The toxicity of exposed maltenes was generally higher than the exposed total oil for most oils, suggesting the aqueous toxicity level was positively related to the formed NAFC intermediates.

Resilience of larval wood frogs (Rana sylvatica) to hydrocarbons and other compounds released from naturally weathered diluted bitumen in a boreal lake.

The risks to aquatic wildlife from spills of diluted bitumen (dilbit) into inland waters are poorly understood. In this paper, we describe the response of larval wood frogs (Rana sylvatica) to hydrocarbons and other compounds released from experimental spills of dilbit in a temperate boreal lake. To simulate a wide range of environmentally relevant oil spill scenarios, different volumes of Cold Lake Winter Blend dilbit (0, 1.5, 2.9, 5.5, 18, 42, 82, and 180 L) were added to 10 m diameter in-lake limnocorrals. Larvae (n = 360) were reared (from Gosner Stage (GS) 25 to ∼42) in land-based aquatic microcosms, where they were first exposed to clean water during a 2-week baseline phase, and then (at GS ∼30), to contaminated water withdrawn from the limnocorrals for 3 weeks. We observed no statistically significant trends in survival, growth, or development of larvae as a consequence of exposure to the chemical compounds released from naturally weathered dilbit. Likewise, neither cytochrome P450 1A biomarkers nor levels of thyroid hormones in wood frogs near metamorphic climax were significantly related to volume of the oil spills. However, there was a modest statistically significant decrease in larval activity (up to 8.7% relative to the control), but no change in other behavioral metrics (i.e., sociality or space use). Our work adds to the limited body of literature on the effects of unconventional oils on aquatic wildlife and helps to inform risk assessments regarding pipeline projects.

Bioaccumulation and toxicokinetics of polycyclic aromatic compounds and metals in giant floater mussels (Pyganodon grandis) exposed to a simulated diluted bitumen spill.

Oil spills constitute a major risk to the environment and the bioaccumulation potential of the derived oil constituents will influence their impact on aquatic biota. Here we determined the bioaccumulation potential and toxicokinetic parameters of polycyclic aromatic compounds (PACs) and various selected metals in the giant floater mussels (Pyganodon grandis) following experimental oil spills in a freshwater lake. Specifically, these mussels were exposed ex situ for 25 days to water contaminated with naturally weathered diluted bitumen (dilbit), a form of oil commonly transported through pipelines. We detected greater concentrations of total PAC in mussels (∑PAC44) exposed to dilbit-contaminated water (25.92-27.79 µg g-1 lipid, n = 9, at day 25 of the uptake phase) compared to mussels from a control with no exposure to dilbit (average of 2.62 ± 1.95 µg g-1 lipid; ±SD, n = 17). This study demonstrates the importance of including alkylated PACs when assessing the impacts of an oil spill as the concentration of alkylated PACs in mussel tissue were an order of magnitude higher than their parent counterparts. However, metal accumulation in dilbit-exposed mussels did not exceed the unexposed controls, suggesting no excess metal accumulation by mussels from a 25-day dilbit exposure. From first-order one-compartment models, mean uptake rate constants (0.78-18.11 L g-1 day-1, n = 29) and bioconcentration factors (log values from 4.02 to 5.92 L kg-1, n = 87) for the 29 individual PACs that accumulated in mussels demonstrated that some alkylated PACs had greater bioaccumulation potential compared to their parent PAC counterpart but for the most part, alkylated and parent PACs had comparable BCF values. Results from this study also demonstrated that giant floater mussels could be used to biomonitor PAC contamination following oil spills as PACs accumulated in mussel tissue and some were still detectable following the 16-day depuration phase. This study provides the largest, most comprehensive set of toxicokinetic and bioaccumulation parameters for PACs and their alkylated counterparts (44 analytes) in freshwater mussels obtained to date.

Effect of spilled diluted bitumen on chemical air-water exchange in boreal lake limnocorrals.

Following spills into water, petroleum oils can spread widely and produce surface slicks. Resulting slicks may impede volatilization and possibly increase chemical persistence in water. While the influence of oil films on chemical air-water exchange has been examined through theoretical and laboratory studies, field studies have not been conducted to assess the relevance of these effects following actual oil spill events. Here we evaluated the effect of diluted bitumen (dilbit) experimentally spilled in limnocorrals installed in a boreal lake on the volatilization of sulfur hexafluoride (SF6), a non-reactive volatile tracer gas. Dilbit spills were monitored over 70 days and SF6 was introduced twice (after 7 and 48 days) to evaluate the influence of spilled dilbit on the loss of SF6 from water. Volatilization rate constants of SF6 (kVOL) significantly decreased by up to 80% with increasing total dilbit spill cover. Using a theoretical equation, decreases in kVOL were largely explained by a reduction in open water area where chemical exchange across the air-water interface occurs. Apparent effects of the slick on SF6 mass transfer were estimated to be smaller by comparison (20%).To account for this reduction in volatilization, oil spill fate models should include a correction to consider the impact of spill cover on the air-water exchange of organic chemicals.

Responses of Wild Finescale Dace (Phoxinus neogaeus) to Experimental Spills of Cold Lake Blend Diluted Bitumen at the International Institute for Sustainable Development-Experimental Lakes Area, Northwestern Ontario.

Pipelines carrying diluted bitumen (dilbit) traverse North America and may result in dilbit release into sensitive freshwater ecosystems. To better understand the potential effects of a freshwater oil release, the Boreal-lake Oil Release Experiment by Additions to Limnocorrals project at the International Institute for Sustainable Development-Experimental Lakes Area (Ontario, Canada) modeled seven dilbit spills contained within a 10-m diameter of littoral limnocorrals in a boreal lake. Wild finescale dace (Phoxinus neogaeus) were released in the limnocorrals 21 days after oil addition and remained there for 70 days. Dilbit volumes covered a large range representing a regression of real spill sizes and total polycyclic aromatic compounds (TPAC) between 167 ng L-1 day-1 and 1989 ng L-1 day-1 . We report the effects of chronic exposure on reproductive potential as well as physiological responses in the gallbladder and liver. In exposures >1000 ng L-1 day-1 , there was a significant decrease in fish retrieval, culminating in zero recapture from the three highest treatments. Among the fish from the limnocorrals with lower levels of TPAC (<500 ng L-1 day-1 ), effects were inconsistent. Gallbladder bile fluorescence for a naphthalene metabolite was significantly different in fish from the oil-exposed limnocorrals when compared to the lake and reference corral, indicating that fish in these lower exposures were interacting with dilbit-derived polycyclic aromatic compounds. There were no significant differences in condition factor, somatic indices, or hepatocyte volume indices. There were also no significant changes in the development of testes or ovaries of exposed dace. The results from the present study may serve to orient policymakers and emergency responders to the range of TPAC exposures that may not significantly affect wild fish. Environ Toxicol Chem 2022;41:2745-2757. © 2022 SETAC.

Determination of polar impurities in biodiesels using solid-phase extraction and gas chromatography-mass spectrometry.

This paper reports on a method for development and validation for simultaneous characterization and determination of oxygenated polar impurities--free fatty carboxylic acids (FFAs), partial glycerides (monoacylglycerides, MGs), residual glycerol and free sterols--in various biodiesels based on the combination of solid-phase extraction (SPE), silylation and GC/MS technologies. The effects of various SPE and silylation conditions on the method recoveries were evaluated. Using this integrated SPE-GC/MS method, 38 target polar compounds (13 FFAs, 17 glycerides and 8 sterols) in 9 biodiesels derived from 4 different feedstocks were successfully separated and quantified. It was found that the carbon chain length of FFAs was ranged from C(6) to C(24), with C(16) and C(18) being the most abundant in all biodiesels. The total FFAs concentration was consistent with the acid values (AVs) measured by standard method ASTM D974-04. MG congeners with carbon number of 18 (mono-C18) were most abundant in the biodiesel samples, followed by mono-C(16) and free glycerol. ß-Sitosterol and campesterol were found to be the prevailing phytosterols in all pure vegetable oil-based biodiesels, while brassicasterol and stigmasterol was only significant in the biodiesel from canola oil and soybean oil, respectively, and abundant cholesterol was only detected in animal fat-based biodiesels.

Method development for fingerprinting of biodiesel blends by solid-phase extraction and gas chromatography-mass spectrometry.

A method based on the combination of solid-phase extraction (SPE) with gas chromatography-mass spectrometry (GC/MS) for detailed chemical fingerprinting of biodiesel/petrodiesel blends was developed in the present study. Forensic identification, commonly referred to as chemical fingerprinting, is based on the relative distributions of individual aliphatic hydrocarbons, aromatic hydrocarbons, fatty acid alkyl esters, and free sterols. Fractionation of fuel samples is optimized for the separation of fatty acid esters and free sterols from petroleum hydrocarbons into four fractions: aliphatic, aromatic, fatty acid ester, and polar components. The final recoveries of aliphatic and aromatic hydrocarbons were determined to be in the range of 65-103%, 73-105% for FAMEs, and 78-103% for free sterols in the polar fraction. Excellent separation with negligible crossover of components with different polarities between fractions was observed. Quantitative analysis of blend levels and individual chemical distribution were achieved. The method has great potential for the identification of biodiesel in diesel fuel blends and could form the basis of a method for characterization of biodiesel-contaminated environmental samples.

Tracking petrogenic hydrocarbons in lakes of the Peace-Athabasca Delta in Alberta, Canada using petroleum biomarkers.

The Peace-Athabasca Delta (PAD) receives a mixture of hydrocarbons from biogenic, pyrogenic, and petrogenic processes. Source apportionment in the PAD has focussed on polycyclic aromatic compounds (PACs), which are ubiquitous in the environment and susceptible to weathering. In contrast, petroleum biomarkers of terpanes, hopanes, and steranes are degradation-resistant organic compounds found uniquely in petroleum products that can identify the input and origin of petrogenic hydrocarbons (PHCs). We provide an analysis of environmentally-relevant PHCs (including n-alkanes, PACs, and petroleum biomarkers) in surficial sediments of strategically selected lakes in the Athabasca and Peace deltas and adjacent boreal uplands. Alkanes were found to be predominately biogenic in all lakes. PAC sources were identified as wood combustion in the upland boreal lakes, a mixture of petrogenic and pyrogenic combustion in two closed-drainage lakes in the Peace Delta, and predominately petrogenic in two flood-prone Athabasca Delta lakes. Using multivariate analyses, raw Alberta oil sands were identified as a potential source of PHCs to the two flood-prone lakes in the Athabasca Delta. Biomarkers of terpanes and hopanes were identified in the Peace Delta and boreal uplands, likely from bitumen and transported atmospherically. These findings validate the use of petroleum biomarkers as tracers for bituminous sands in surficial lake sediments and their potential use in paleolimnological investigations at the PAD to improve understanding of relative roles of natural and industrial processes on far-field deposition of PHCs.

Occurrence, characterization, source, and risk assessment of petroleum-related hydrocarbons in sediments along St. Clair River, Ontario, Canada.

Total petroleum hydrocarbons (TPH), n-alkanes, petroleum biomarkers, and polycyclic aromatic hydrocarbons (PAHs) were analyzed in the sediments collected from the shorelines and bottom of St. Clair River, Ontario, Canada. Most of the sampling sites had low TPH (< 20 µg/g). River bottom sediment usually had higher level of TPHs, total alkanes, total biomarkers, and total PAHs than most of the shoreline ones. Mixed biogenic and petrogenic n-alkanes were present in all the sites. Most sites had trace amounts of petroleum biomarkers. Mixed pyrogenic and petrogenic inputs with the predominant petroleum, have contributed to the detected PAHs at all sampling sites. PAHs detected would not show potential toxicity to benthic organisms in all shoreline sampling sites; however, some light molecular weight PAHs (e.g., phenanthrene, 2-methyl naphthalene, and acenaphthylene) are anticipated to have possible adverse impacts to sediment-dwelling organisms in part of the river bottom sediment.

Occurrence, characterization, and ecological assessment of petroleum-related hydrocarbons on the shoreline of Fraser River Delta, British Columbia, Canada.

The Fraser River Delta is a unique and dynamic region supporting the diverse ecosystems and habitats in the Canadian West Coast. Total petroleum hydrocarbons (TPH), n-alkanes, petroleum biomarkers, and polycyclic aromatic hydrocarbons (PAHs) were analyzed for the intertidal sediments taken from the shorelines of the Delta area, British Columbia, Canada, to establish the baseline background data. Most of the sampling sites had low TPH (< 40 µg/g); only two samples had TPH from 100 to 150 µg/g. Mainly biogenic n-alkanes were present in all sites. Non-detectable to trace amounts of petroleum biomarkers were found at most sites. Mixed pyrogenic and petrogenic inputs contributed to the presence of PAHs at most sites. PAHs are not present in amounts anticipated negative effects to benthic organisms in all sampling sites, except that benzo (a) pyrene (BaP) from the upper intertidal zone (UIZ) of Burnaby Fraser Foreshore Park may have possible adverse biological effects.

Simulating diluted bitumen spills in boreal lake limnocorrals - Part 1: Experimental design and responses of hydrocarbons, metals, and water quality parameters.

Large-scale, in-lake enclosures (limnocorrals) were used to simulate spills of diluted bitumen (dilbit) in a boreal lake. In this study we use these simulated spills, which covered a range of sizes (oil:water ratio) representative of the upper 25% of onshore crude oil spills in North America (2008-2019), to assess the fate of dilbit-derived hydrocarbons and metals as well as the impacts of the spills on standard water quality parameters. The systems were monitored over 70 days following the application of dilbit amounts ranging between 1.5 and 179.8 L into 10-m diameter, ~100 m3 limnocorrals. The concentration of total petroleum hydrocarbons (TPH) in the water column increased rapidly over the first two weeks reaching a plateau that ranged between 200 µg/L and 2200 µg/L for the lowest and highest treatment respectively. The concentration of total polycyclic aromatic compounds (PACs) also increased over the first two weeks, prior to a slow decrease until day 70. The maximum measured concentrations in the highest treatment were 2858 ng/L for the sum of all 46 quantified PACs, 2716 ng/L for alkylated PACs and 154 ng/L for the 16 EPA priority PAHs. The concentrations of PACs in the sediment increased continuously over the study in the three highest treatments with maximum observed concentrations of 189 ng/g for ΣPAC46, 169 ng/g for ΣPACalk. No significant treatment-related changes in the 16 EPA priority PAHs were observed in the sediment. Of the 25 metals quantified in the water column, only manganese, molybdenum, and vanadium displayed a significant treatment effect with increases of 280, 76 and 25% respectively in the total fraction. These results can help us understand and predict the fate of oil-derived contaminants following a spill and characterize the exposure of freshwater organisms living within them. These results should help inform the risk assessment of future dilbit transportation projects.

Application of gas chromatography-high resolution quadrupole time-of-flight mass spectrometry in fingerprinting analysis of polycyclic aromatic sulfur heterocycles.

Polycyclic aromatic sulfur heterocycles (PASHs), as a group of major sulfur-containing compounds, widely occur in crude oil and its refined products. Accurate analyses of these petrochemical components play an important role in monitoring oil quality, forensic source identification, and assessment of environmental impact of an oil spill. PASHs occur at relatively lower abundances in most crude oils and refined petroleum products than their corresponding aromatic hydrocarbons and are co-eluted together with some petroleum hydrocarbons in chromatographic analysis, resulting in high uncertainty for their quantitation. Capillary gas chromatography coupled with a quadrupole time-of-flight mass spectrometry (GC-QTOF-MS) provides high resolution and high mass accuracy, which facilitates discrimination of the delicate mass defects of isobaric compounds with the same nominal mass and external matrix material. In this work, GC-QTOF-MS was applied to analyze bicyclic to pentacyclic PASHs including benzothiophenes, dibenzothiophenes, benzonaphthothiophenes, dinaphthothiophenes and their C1- to C4- alkylated homologues in a number of crude oils, refined petroleum products, and environmental samples. GC-QTOF-MS analysis substantially improved the identification confidence and reduced quantitation uncertainty of PASHs and polycyclic aromatic hydrocarbons (PAHs) by eliminating the interferences presented in nominal mass chromatograms.

Biodegradation potential assessment by using autochthonous microorganisms from the sediments from Lac Mégantic (Quebec, Canada) contaminated with light residual oil.

In July 2013, a fatal train derailment led to an explosion and fire in the town of Lac-Mégantic (LM), Quebec, and the crude oil contamination of regional surface water, soil, and sediment in the adjacent Lake Mégantic. This study investigated the degradation potential of the spilled crude oil by using the sediments from the incident site as the source of microorganisms. Two light crude oils (LM source oil and Alberta Sweet Mixed Blend (ASMB)) were tested at 22 °C for 4 weeks and 4 °C for 8 weeks, respectively. The post-incubation biological and chemical information of the samples were analysed. There was no marked difference in degradation efficacy and biological activities for both the LM and ASMB oils, although the biodegradation potential differed between the two incubations. Higher temperature favoured the growth of microorganisms, thus for the degradation of all petroleum hydrocarbons, except for some conservative biomarkers. The degradation of both oils followed the order of resolved components > total saturated hydrocarbons (TSH) > unresolved complex mixture (UCM) >total aromatic hydrocarbons (TAH). Normal alkanes were generally degraded more significantly than branched ones, and polycyclic aromatic hydrocarbons (PAHs). Degradation of polycyclic aromatic hydrocarbons (PAHs) and their alkylated congeners (APAHs) for both incubations generally decreased as the number of aromatic rings, and the degree of alkylation increased. This study showed that the LM sediments can biodegrade the petroleum hydrocarbons efficaciously if appropriate ambient temperatures are generated to favour the growth of autochthonous microorganisms.