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.
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•BSs, ADs, DAs, MASs and TASs were analysed in solar irradiated CLB and MSW.•BSs, ADs, and DAs were exhaustively evaporated like the C10–C17 range alkanes.•The photolysis of MASs and TASs were slower than PAHs at the similar aromatic rings.•The photolytic loss of MASs and TASs were greater than alkanes at same carbon range.•Only MASs and TASs can be used to evaluate photolytic behavior of petroleum oil.
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.
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•n-alkanes and terpanes were photo-oxidized negatively, while PAHs were photo-oxidized fastest.•PAH removal in matlenes were usually faster than in the total oil.•The characteristics and abundance of NAFCs were not affected by the deasphalting process.•Deasphalteneing process enhanced the formation of NAFCs, especially for the Oo species.•The toxicity of exposed maltenes was generally higher than that of the exposed total oil for most oils.
Tailings ponds in the oil sands region (OSR) of western Canada are suspected sources of polycyclic aromatic hydrocarbons (PAHs) to the atmosphere. In the absence of detailed characterization or ...direct flux measurements, we present preliminary measurement-based estimates of the emissions of thirteen priority PAHs from the ponds. Using air concentrations measured under the Joint Canada-Alberta Oil Sands Monitoring Plan and water concentrations from a small sampling campaign in 2013, the total flux of 13 US EPA priority PAHs (fluorene to benzoghiperylene) was estimated to be upward from water to air and to total 1069 kg y−1 for the region as a whole. By comparison, the most recent air emissions reported to Canada's National Pollutant Release Inventory (NPRI) from oil sands facilities totalled 231 kg y−1. Exchange fluxes for the three remaining priority PAHs (naphthalene, acenaphthylene and acenaphthene) could not be quantified but evidence suggests that they are also upward from water to air. These results indicate that tailings ponds may be an important PAH source to the atmosphere that is missing from current inventories in the OSR. Uncertainty and sensitivity analyses lend confidence to the estimated direction of air–water exchange being upward from water to air. However, more detailed characterization of ponds at other facilities and direct flux measurements are needed to confirm the quantitative results presented herein.
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•Tailings ponds in the oil sands region are a suspected source of PAHs to air.•No systematic measurements have yet been made to quantify those emissions.•We have combined air monitoring data with results of a water sampling campaign.•Exchange estimates suggest that net fluxes are upward from water to air.•Further measurements are needed to confirm these preliminary results.
•eliminating or reducing internal and external interferences to PASH analysis.•increasing detection selectivity by using exact monoisotopic mass.•improving identification confidence and quantitation ...accuracy of PASHs and PAHs.•full-spectrum acquisition data for elucidation of refinery intermediates.
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.
The characterization of spilled petroleum products in an oil spill is necessary for identifying the spill source, selection of clean-up strategies, and evaluating potential environmental and ...ecological impacts. Existing standard methods for the chemical characterization of spilled oils are time-consuming due to the lengthy sample preparation for analysis. The main objective of this study is the development of a rapid screening method for the fingerprinting of spilled petroleum products using excitation/emission matrix (EEM) fluorescence spectroscopy, thereby delivering a preliminary evaluation of the petroleum products within hours after a spill. In addition, the developed model can be used for monitoring the changes of aromatic compositions of known spilled oils over time. This study involves establishing a fingerprinting model based on the composition of polycyclic and heterocyclic aromatic hydrocarbons (PAH and HAHs, respectively) of 130 petroleum products at different states of evaporative weathering. The screening model was developed using parallel factor analysis (PARAFAC) of a large EEM dataset. The significant fluorescing components for each sample class were determined. After which, through principal component analysis (PCA), the variation of scores of their modeled factors was discriminated based on the different classes of petroleum products. This model was then validated using gas chromatography-mass spectrometry (GC-MS) analysis. The rapid fingerprinting and the identification of unknown and new spilled oils occurs through matching the spilled product with the products of the developed model. Finally, it was shown that HAH compounds in asphaltene and resins contribute to ≥4-ring PAHs compounds in petroleum products.
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•Aromatic composition of oils was studied via excitation/emission matrix (EEM).•Parallel factor analysis was used to decompose the 3D EEM data.•Principal component analysis was used for classification of petroleum products.•This model can be used for identification and monitoring of new oil spills.
The fate and behavior of diluted bitumen spilled in marine conditions has recently become a topic of much interest, yet, only limited knowledge is available. One of the major issues of a diluted ...bitumen spill on water is whether the product will sink, especially when suspended sediment is present in the water column. This study demonstrated how weathering processes influenced the key spill-related properties of a diluted bitumen product (Cold Lake Blend-Winter), and how interaction of diluted bitumen with sediment affected its tendency to float or sink in water. This study showed that the weathering states of the oils as well as the size of sediment are important factors influencing oil-sediment interactions and the tendency of the formed oil-particulate aggregates for buoyancy. When mixing with fine- and medium-sized sediments, the fresh to moderately weathered oils formed oil-particulate aggregates and sank in saltwater, while the very heavily-weathered oil formed discrete free-floating tarballs.
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•The fate and behavior of spilled diluted bitumen in the marine environment were studied.•The interactions of fresh and weathered sates of diluted bitumen with three types of sediments were evaluated.•The physical properties of the oil-particulate aggregates (density, morphology, particle size and buoyancy) were evaluated.
Following the 16TAN Husky oil spill along the North Saskatchewan River (NSR), the occurrence and natural attenuation of the petroleum hydrocarbons were assessed by analyzing the littoral zone ...sediments/oil debris collected from July 2016 to October 2017. Husky oil-free, mixed sediment-Husky oil, and Husky oil debris samples were identified for all the collected samples. Shoreline sediments were contaminated by mixed biogenic, pyrogenic and petrogenic inputs prior to the spill. Oil stranded on the shoreline of NSR was moved or buried due to the very dynamic conditions of the shoreline, or cleaned through a series of cleanup activities after the spill. Most normal alkanes were naturally weathered, whereas most of the branched alkanes and all of the saturated petroleum biomarkers remained. Some lighter molecular weight (e.g., 2 to 3-ring) polycyclic aromatic hydrocarbons (PAHs) were lost rapidly after the spill, whereas sulfur containing components, e.g., dibenzothiophenes and benzonaphthothiiophenes, and those having a heavier molecular weight did not change markedly even 15 months post-spill. Similarly, some light hydrocarbons (e.g., <C10) were lost over the first kilometers from the point of entry (POE), while heavier hydrocarbons did not show any major differences away from the POE. Very large inter-site and inter-survey discrepancies were found for samples. Evaporation into the air and dissolution into water, combined with biodegradation, were together or independently the main contributors to the loss of the light molecular hydrocarbons.
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•Petrogenic contamination existed on the NSR shoreline prior to the spill.•TPH varied seasonally due to dynamic shoreline condition or cleanup activities post-spill.•Most components with light molecular weights were depleted exhaustively and rapidly post-spill.•Mainly physical processes (evaporation and dissolution) worked for removing oil.•Weathering of petroleum hydrocarbons was compound-specific and environmentally sensitive.
The oil contamination status at the 16TAN spill site changed over the seasons, which can be ascribed to the specific geographic feature of the NSR shoreline causing the bury/movement of oil residues, or the Husky cleanup strategies have helped the remediation. Most of the light molecular hydrocarbons and normal alkanes were depleted rapidly after the spill, while heavy PAHs and branched alkanes did not change markedly even 15-months post-spill.
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
-alkanes, polycyclic aromatic hydrocarbons (PAHs), and oil biomarkers in dilbit over time, as it naturally weathered for 70 days. Depletion rate constants (
) of
-alkanes and PAHs ranged from 0.0009 to 0.41 d
and 0.0008 to 0.38 d
, respectively. There was no significant relationship between
and spill volume, suggesting that spill size did not influence the depletion of petroleum hydrocarbons from the slick. Diagnostic ratios calculated from concentrations of
-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.
Factors affecting oxidation stability for several commercially available biodiesels were primarily investigated by acid value (AV) and induction period (IP) evaluations in this study. It was found ...that the measured IP at different storage time points were somewhat dependent on the saturated degree of fatty acid methyl esters (FAMEs), the corresponding measured AV scattered randomly. Generally, AV increased and IP decreased after one year of storing in a dark cold room in an air‐tight tank. Solvents (methanol, acetone and water) did not show a contribution to altering IP. Metals (copper and lead) showed the strongest detrimental effects to oxidative stability although somewhat depending on the particle size and oxide coating thickness, however, aluminum alloy and steel were not the case. Among the antioxidants, pyrogallol (PY) was the best in enhancing IP with a concentration of less than 3000ppm, however, tert-butylhydroquinone (TBHQ) was the best after 3000ppm, followed by propyl gallate (PG), butylated hydroxyanisole (BHA), 3,5-di-tert-butyl-4-hydroxyltoluene (BHT), and α-tocopherol. The appropriate dosage of PY was also evaluated to achieve the specified IP regulated by EN-14112 for samples with copper or lead contamination.
► Induction period (IP) not acid value (AV) depended on the saturated degree of FAME. ► AV increased but IP decreased after one year storage in -4°C in air tight tanks. ► Cu and Pb showed strong catalytic effects on deteriorate the quality of biodiesels. ► Solvents and metals (steel and aluminum) did not alter IP significantly. ► Selective antioxidants extended the IP of biodiesels with/without metal presence.
In this study, the water accommodated and particle-laden hydrocarbon species, and the toxicity of the aqueous phase after oil-sediment interactions by varying the weathering states of diluted bitumen ...(Cold Lake blend (CLB)), oil type from light to heavy, and sediment type. Compared to the original oils, the sediment-laden total petroleum hydrocarbons (TPH) contained fewer hydrocarbons in the carbon range <C10, comparable contents in C10–C16 range, higher contents in both the C16–C34 and >C34 range. Sediment-laden oil amounts generally decreased with an increased viscosity and asphaltene content of the test oils, as well as with increased sediment particle size. The presence of sediments significantly decreased the oil accommodated in water due to the formation of oil particulate aggregates (OPA) after mixing and settling. Less water accommodated TPH and polycyclic aromatic hydrocarbons (PAHs) were observed for weathered CLB products. However, oil and sediment types did not clearly affect the water accommodated TPH and PAHs. Light molecular PAHs and their alkylated congeners accounted for most of the water accommodated PAH congeners. A microtoxicity test demonstrated that with or without sediment, and regardless of sediment type, the toxicity of the water phase did not change significantly. Light oil of Alberta sweet mixed blend (ASMB) had the highest toxicity, followed by fresh CLB, and then all other oils, suggesting that ASMB and fresh CLB had relatively higher levels of light toxic components dissolved in the water phase compared with the other tested oils.
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•Sediment-laden TPH contained fewer <C10, but higher C16–C34 and >C34 range hydrocarbons.•Increased oil viscosity, asphaltene content, and sediment size decreased sediment-laden TPH.•Less water accommodated TPH and PAHs were observed for weathered CLB products.•Oil and sediment types did not clearly affect the water accommodated TPH and PAHs.•Toxicity of the water phase did not vary with sediment type, but vary with oil type.
