Application of gas chromatography/tandem mass spectrometry to determine a wide range of petrogenic alkylated polycyclic aromatic hydrocarbons in biotic samples

Aquatic toxicity and chemical fate of diluted bitumen spills in freshwater under natural weathering

Increasing global demands for oils are fueling the production of diluted bitumen (DB) from Canada's oil sands region. More weathered than conventional crude (CC) oils, Alberta bitumen is often diluted with lighter petroleum oils to reduce density and viscosity to meet pipeline specifications for transportation. Being a heavy oil product that is transported in large volumes across Canada and the USA, there has been interest to compare its behavior and toxicity characteristics when spilled to those of CC. To determine the influence of environmental weathering upon DB following a freshwater spill, we conducted separate controlled spills of Cold Lake Blend DB and Mixed Sweet Blend light CC oil in a mesocosm spill-tank system at 24 °C with wave-action for 56 days. DB-contaminated waters remained acutely lethal for a period of 14 days to early life stage fathead minnows (Pimephales promelas) exposed during embryologic development, while CC was lethal for 1 day. However, concentrations of mono- and polycyclic aromatic compounds, often claimed to be principally responsible for the acute and chronic toxicity of crude oils, were consistently higher in CC water compared to DB. Elevated aromatic concentrations in CC water correlated with higher prevalences of developmental malformations, reduced heart and growth rates, and impacts on the aryl hydrocarbon receptor pathway. Organic acids were measured over the course of the studies and O2 containing naphthenic acids were present at greater relative abundances in DB- compared to CC-contaminated water, with their attenuation correlating with reduced acute and sublethal toxicity. Furthermore, organic acid degradation products accumulated with time and likely contributed to the consistently sublethal toxicity of the weathered oils throughout the experiment. Improved characterization of the fractions including organic acids and those organic compounds found within the unresolved complex mixture of fresh and weathered crude oils is necessary to adequately understand and prepare for the risks that accidental petroleum spills pose to aquatic resources.

Rapid and sensitive method for the simultaneous determination of PAHs and alkyl-PAHs in scrubber water using HS-SPME-GC-MS/MS

Scrubber water, a waste stream generated by ships exhaust gas cleaning systems, may pose a threat when released into the marine environment due to potential contamination with polycyclic aromatic hydrocarbons (PAHs) and their alkyl derivatives (alkyl-PAHs). This study aims to develop a reliable analytical procedure combining headspace solid-phase microextraction (HS-SPME) with gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-MS/MS) to simultaneously separate and determine target compounds in aqueous samples. Method validation demonstrated good linearity up to 200 ng L-1 (r2> 0.996) and low limits of detection (0.33 to 1.67 ng L-1, except for naphthalene at 3.3 ng L-1). The method shows good precision (RSD<20%) and satisfactory analytical recoveries. The methodology was successfully applied to scrubber water samples collected from a container ship and the results highlight the prevalence of naphthalene, phenanthrene, and their alkyl derivatives.•Rapid and reproducible HS-SPME-GC-MS/MS method for the analysis of PAHs and alkyl-PAHs in scrubber water.•The capacity of SPME to analyze both filtered and unfiltered samples was assessed, showing that the more hydrophobic PAHs may be lost during filtration.

Characterisation of former manufactured gas plant soils using parent and alkylated polycyclic aromatic hydrocarbons and Rock-Eval(6) pyrolysis

Soils sampled from 10 former manufactured gas plants (MGP) in the UK were investigated using gas chromatography mass spectrometry (GC-MS/MS) and Rock-Eval (6) Pyrolysis (RE). RE is a screening tool used to characterise bulk organic matter in soils via the release of carbon compounds during pyrolysis and oxidation. Both the distributions and concentrations of 30 parent and 21 alkylated polycyclic aromatic hydrocarbons (PAHs) and the parameters of RE were analysed to establish relationships between soils and the MGP processes history. Principal component analysis (PCA) using the PAHs distributions and RE parameters can assist with differentiating between MGP processes. MGP processes utilizing oil provided the clearest results, attributed to petrogenic signatures with high proportions of low molecular weight PAHs. Processes using lower temperature processes were distinguished by higher proportions of high molecular weight PAHs. RE parameters alone were unable to distinguish MGP processes but showed potential in estimating the lability and thus the amount of PAH that could be released from soils. This research provides new insights that may be useful in understanding and characterising the risks posed to human health from PAHs in soils.

Biological Responses of Pacific Herring Embryos to Crude Oil Are Quantifiable at Exposure Levels Below Conventional Limits of Quantitation for PAHs in Water and Tissues

Pacific herring (Clupea pallasii), a cornerstone of marine food webs, generally spawn on marine macroalgae in shallow nearshore areas that are disproportionately at risk from oil spills. Herring embryos are also highly susceptible to toxicity from chemicals leaching from oil stranded in intertidal and subtidal zones. The water-soluble components of crude oil trigger an adverse outcome pathway that involves disruption of the physiological functions of cardiomyocytes in the embryonic herring heart. In previous studies, impaired ionoregulation (calcium and potassium cycling) in response to specific polycyclic aromatic hydrocarbons (PAHs) corresponds to lethal embryolarval heart failure or subtle chamber malformations at the high and low ends of the PAH exposure range, respectively. Sublethal cardiotoxicity, which involves an abnormal outgrowth (ballooning) of the cardiac ventricular chamber soon after hatching, subsequently compromises juvenile heart structure and function, leading to pathological hypertrophy of the ventricle and reduced individual fitness, measured as cardiorespiratory performance. Previous studies have not established a threshold for these sublethal and delayed-in-time effects, even with total (∑)PAH exposures as low as 29 ng/g of wet weight (tissue dose). Here, we extend these earlier findings showing that (1) cyp1a gene expression provides an oil exposure metric that is more sensitive than typical quantitation of PAHs via GC-MS and (2) heart morphometrics in herring embryos provide a similarly sensitive measure of toxic response. Early life stage injury to herring (impaired heart development) thus occurs below the quantitation limits for PAHs in both water and embryonic tissues as a conventional basis for assessing oil-induced losses to coastal marine ecosystems.

Characterization of scrubber water discharges from ships using comprehensive suspect screening strategies based on GC-APCI-HRMS

An extended suspect screening approach for the comprehensive chemical characterization of scrubber discharge waters from exhaust gas cleaning systems (EGCSs), used to reduce atmospheric shipping emissions of sulphur oxides, was developed. The suspect screening was based on gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS) and focused on the identification of polycyclic aromatic hydrocarbons (PAHs) and their alkylated derivatives (alkyl-PAHs), which are among the most frequent and potentially toxic organic contaminants detected in these matrices. Although alkyl-PAHs can be even more abundant than parent compounds, information regarding their occurrence in scrubber waters is scarce. For compound identification, an in-house compound database was built, with 26 suspect groups, including 25 parent PAHs and 23 alkyl-PAH homologues. With this approach, 7 PAHs and 12 clusters of alkyl-PAHs were tentatively identified, whose occurrence was finally confirmed by target analysis using GC coupled with tandem mass spectrometry (GC-MS/MS). Finally, a retrospective analysis was performed to identify other relevant (poly)cyclic aromatic compounds (PACs) of potential concern in scrubber waters. According to it, 18 suspect groups were tentatively identified, including biphenyls, dibenzofurans, dibenzothiophenes and oxygenated PAHs derivatives. All these compounds could be used as relevant markers of scrubber water contamination in heavy traffic marine areas and be considered as potential stressors when evaluating scrubber water toxicity.

Co-Exposure of Phenanthrene and the cyp-Inducer 3-Methylchrysene Leads to Altered Biotransformation and Increased Toxicity in Fish Egg and Larvae

Polycyclic aromatic hydrocarbons (PAHs) have frequently been suspected of governing crude oil toxicity because of similar morphological defects in fish. However, PAH concentrations are often not high enough to explain the observed crude oil toxicity. We hypothesize that one PAH can enhance the metabolism and toxicity of another PAH when administered as a mixture. Early life stage Atlantic haddock (Melanogrammus aeglefinus) were in this study exposed to phenanthrene in the presence and absence of 3-methylchrysene that is known to induce the metabolic enzyme cytochrome P450 1A via cyp1a gene expression. Uptake, metabolism, and multiple toxicity endpoints were then measured in a time-course study up to 3 days post-hatching. Passive dosing provided aqueous concentrations ≈180 μg/L for phenanthrene and ≈0.6 μg/L for 3-methylchrysene, which resulted in tissue concentrations ≈60 μg/g ww for phenanthrene and ≈0.15 μg/g ww for 3-methylchrysene. The low concentration of 3-methylchrysene led to the elevated expression of cyp1a but no toxicity. Levels of phenanthrene metabolites were 5-fold higher, and morphological defects and cardiotoxicity were consistently greater when co-exposed to both compounds relative to phenanthrene alone. This work highlights the metabolic activation of PAH toxicity by a co-occurring PAH, which can lead to excess toxicity, synergistic effects, and the overproportional contribution of PAHs to crude oil toxicity.

Cardiac toxicity of phenanthrene depends on developmental stage in Atlantic cod (Gadus morhua)

Complex mixtures like crude oil, and single components such as Phenanthrene (Phe), induce cardiotoxicity by interfering with excitation-contraction coupling. However, recent work has demonstrated that the timing of pollutant exposure during embryogenesis greatly impacts the degree of cardiac dysfunction caused. Here, we aimed to clarify the temporal dependence of Phe toxicity and the downstream effects of cardiac dysfunction using Atlantic cod (Gadus morhua). Phe (nominal concentration, 1.12 μmol/L), or the L-type‑calcium channel blocker Nicardipine (Nic) (nominal concentration, 2 and 4 μmol/L), were individually applied to cod embryos either during cardiogenesis (early) or after the onset of cardiac function (late). Phe toxicity was highly dependent on the timing of exposure. Exposure after the onset of cardiac function (i.e. late) caused more severe cardiac and extracardiac abnormalities at 3 days post hatching (dph) than early exposure. Late Phe exposure resulted in a smaller ventricle, eliminated ventricular contraction, and reduced atrial contraction. In contrast, early Phe exposure did not have an effect on cardiac development and function. This temporal difference was not as evident in the Nic treatment. Early Nic exposure created similar morphological phenotypes to the late Phe exposure. The two treatments (early Nic and late Phe) also shared a cardiofunctional phenotype, comprised of eliminated ventricular, and reduced atrial, contraction. These data suggest that extracardiac abnormalities, such as the craniofacial deformities seen after late embryonic exposure to cardiotoxic oil components and mixtures, are mostly downstream effects of cardiac dysfunction.

No observed developmental effects in early life stages of capelin (Mallotus villosus) exposed to a water-soluble fraction of crude oil during embryonic development

The rise in offshore oil and gas operations, maritime shipping, and tourism in northern latitudes enhances the risk of oil spills to sub-Arctic and Arctic coastal environments. Therefore, there is a need to understand the potential adverse effects of petroleum on key species in these areas. Here, we investigated the effects of oil exposure on the early life stages of capelin (Mallotus villosus), an ecologically and commercially important Barents Sea forage fish species that spawns along the coast of Northern Norway. Capelin embryos were exposed to five different concentrations (corresponding to 0.5-19 µg/L total PAHs) of water-soluble fraction (WSF) of crude oil from 6 days post fertilization (dpf) until hatch (25 dpf), and development of larvae in clean seawater was monitored until 52 dpf. None of the investigated endpoints (embryo development, larval length, heart rate, arrhythmia, and larval mortality) showed any effects. Our results suggest that the early life stages of capelin may be more robust to crude oil exposure than similar life stages of other fish species.

Crude oil exposure of early life stages of Atlantic haddock suggests threshold levels for developmental toxicity as low as 0.1 μg total polyaromatic hydrocarbon (TPAH)/L

Atlantic haddock (Melanogrammus aeglefinus) embryos bind dispersed crude oil droplets to the eggshell and are consequently highly susceptible to toxicity from spilled oil. We established thresholds for developmental toxicity and identified any potential long-term or latent adverse effects that could impair the growth and survival of individuals. Embryos were exposed to oil for eight days (10, 80 and 300 μg oil/L, equivalent to 0.1, 0.8 and 3.0 μg TPAH/L). Acute and delayed mortality were observed at embryonic, larval, and juvenile stages with IC₅₀ = 2.2, 0.39, and 0.27 μg TPAH/L, respectively. Exposure to 0.1 μg TPAH/L had no negative effect on growth or survival. However, yolk sac larvae showed significant reduction in the outgrowth (ballooning) of the cardiac ventricle in the absence of other extracardiac morphological defects. Due to this propensity for latent sublethal developmental toxicity, we recommend an effect threshold of 0.1 μg TPAH/L for risk assessment models.

Alkyl-phenanthrenes in early life stage fish: differential toxicity in Atlantic haddock (Melanogrammus aeglefinus) embryos

Tricyclic polycyclic aromatic hydrocarbons (PAHs) are believed to be the primary toxic components of crude oil. Such compounds including phenanthrene are known to have direct effects on cardiac tissue, which lead to malformations during organogenesis in early life stage fish. We tested a suite of 13 alkyl-phenanthrenes to compare uptake and developmental toxicity in early life stage haddock (Melanogrammus aeglefinus) embryos during gastrulation/organogenesis beginning at 2 days post fertilization via passive dosing. The alkyl-phenanthrenes were tested at their solubility limits, and three of them also at lower concentrations. Measured body burdens were linearly related to measured water concentrations. All compounds elicited one or more significant morphological defects or functional impairment, such as decreased length, smaller eye area, shorter jaw length, and increased incidence of body axis deformities and eye deformities. The profile of developmental toxicities appeared unrelated to the position of alkyl substitution, and gene expression of cytochrome 1 a (cyp1a) was low regardless of alkylation. Mortality and sublethal effects were observed below the expected range for baseline toxicity, thus indicating excess toxicity. Additionally, PAH concentrations that resulted in toxic effects here were far greater than when measured in whole crude oil exposures that cause toxicity. This work demonstrates that, while these phenanthrenes are toxic to early life stage fish, they cannot individually account for most of the developmental toxicity of crude oil, and that other compounds and/or mixture effects should be given more consideration.

Non-target and suspect screening reveal complex pattern of contamination in Arctic marine zooplankton

Although increasing, there is still limited knowledge of the presence of 'contaminants of emerging concern' in Arctic marine biota, particularly in lower trophic species. In the present study, we have applied a novel pipeline to investigate the presence of contaminants in a variety of benthic and pelagic low-trophic organisms: amphipods, copepods, arrow worms and krill. Samples collected in Kongsfjorden in Svalbard in 2018 were subject to extraction and two-dimensional gas chromatography coupled to high-resolution mass spectrometry (GC×GC-HRMS). Tentatively identified compounds included plastic additives, antioxidants, antimicrobials, flame retardants, precursors, production solvents and chemicals, insecticides, and pharmaceuticals. Both legacy contaminants (PAHs, PCBs, PBDEs, hexachlorobenzene) as well as novel and emerging contaminants (triclosan, bisphenol A, and ibuprofen) were quantified in several species using target analysis by GC-MS/MS. The significance of these discoveries is discussed considering the potential for detrimental effects caused by these chemicals, as well as suggested local and distant sources of the components to the Arctic environment.

Co-exposure to UV radiation and crude oil increases acute embryotoxicity and sublethal malformations in the early life stages of Atlantic haddock (Melanogrammus aeglefinus)

Crude oil causes severe abnormalities in developing fish. Photomodification of constituents in crude oil increases its toxicity several fold. We report on the effect of crude oil, in combination with ultraviolet (UV) radiation, on Atlantic haddock (Melanogrammus aeglefinus) embryos. Accumulation of crude oil on the eggshell makes haddock embryos particularly susceptible to exposure. At high latitudes, they can be exposed to UV radiation many hours a day. Haddock embryos were exposed to crude oil (5-300 μg oil/L nominal loading concentrations) for three days in the presence and absence of UV radiation (290-400 nm). UV radiation partly degraded the eggs' outer membrane resulting in less accumulation of oil droplets in the treatment with highest oil concentration (300 μg oil/L). The co-exposure treatments resulted in acute toxicity, manifested by massive tissue necrosis and subsequent mortality, reducing LC50 at hatching stage by 60 % to 0.24 μg totPAH/L compared to 0.62 μg totPAH/L in crude oil only. In the treatment with nominal low oil concentrations (5-30 μg oil/L), only co-exposure to UV led to sublethal morphological heart defects. Including phototoxicity as a parameter in risk assessments of accidental oil spills is recommended.

Monitoring ocean water quality by deployment of lumpfish (Cyclopterus lumpus) eggs: In situ bioaccumulation and toxicity in embryos

Fish embryos can bioaccumulate and are particularly sensitive to a wide range of contaminants, which makes them suitable sentinels for environmental biomonitoring. However, fish embryos are very rarely utilized in environmental monitoring surveys, possibly due to their fragility and seasonality. In the present work, we assessed the applicability of caged lumpfish (Cyclopterus lumpus) eggs for in situ biomonitoring of exposure and effects of organic contaminants focusing on polyaromatic hydrocarbons and phenolic compounds. Fertilized eggs (1 dpf) were transplanted for 17-19 days at different locations that differed in terms of contaminant load, depths and weather conditions, namely at three stations close to the city of Trondheim (two harbour areas and a one in the Fjord) and three stations at a coastal aquaculture facility. High survival upon retrieval after deployment showed that lumpfish eggs are relatively robust and survive encaging in different environments. Bioaccumulation of organic contaminants (PAHs and phenolic compounds) was measured and potential effects on hatching, development, survival and larvae morphometry were determined. Chemical analyses showed that especially PAHs were effectively accumulated in eggs in contaminated sites, with concentrations of ƩPAHs being 15 - 25 times higher in harbour areas compared to those at the aquaculture facility. A higher incidence of embryonic deformations was observed in the most polluted deployment location, but larvae morphometry revealed no evidence of toxicity related to pollutant body burden. In conclusion, the in-situ exposure method was proven to work well, making it attractive for implementations in environmental monitoring programs.

The effects of polycyclic aromatic compounds (PACs) on mammalian ovarian function

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Toxicity of polycyclic aromatic compounds (PACs) is limited to a subset of PACs.

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Exposure to these compounds impact major processes necessary for ovarian function.

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PAC exposure causes follicle loss and aberrant steroid production and angiogenesis.

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PAC exposure may increase the risk for impaired fertility and ovarian pathologies.

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The study of PACs as ovarian toxicants should include additional compounds.

Polycyclic aromatic compounds (PACs) are a broad class of contaminants ubiquitously present in the environment due to natural and anthropogenic activities. With increasing industrialization and reliance on petroleum worldwide, PACs are increasingly being detected in different environmental compartments. Previous studies have shown that PACs possess endocrine disruptive properties as these compounds often interfere with hormone signaling and function. In females, the ovary is largely responsible for regulating reproductive and endocrine function and thus, serves as a primary target for PAC-mediated toxicity. Perturbations in the signaling pathways that mediate ovarian folliculogenesis, steroidogenesis and angiogenesis can lead to adverse reproductive outcomes including polycystic ovary syndrome, premature ovarian insufficiency, and infertility. To date, the impact of PACs on ovarian function has focused predominantly on polycyclic aromatic hydrocarbons like benzo(a)pyrene, 3-methylcholanthrene and 7,12-dimethylbenz[a]anthracene. However, investigation into the impact of substituted PACs including halogenated, heterocyclic, and alkylated PACs on mammalian reproduction has been largely overlooked despite the fact that these compounds are found in higher abundance in free-ranging wildlife. This review aims to discuss current literature on the effects of PACs on the ovary in mammals, with a particular focus on folliculogenesis, steroidogenesis and angiogenesis, which are key processes necessary for proper ovarian functions.

Polycyclic aromatic hydrocarbons in aquatic animals: a systematic review on analytical advances and challenges

Polycyclic aromatic hydrocarbons (PAHs), the main component of petroleum, are a concern due to their environmental persistence, long-range transport, and potential toxic effects on animal, human health, and the environment. PAHs are considered persistent compounds and can be bioaccumulated in sediments and aquatic biota. Determining PAHs in animals and environmental samples consists of three steps: extraction, clean-up or purification, and analytical determination. The matrix complexity and the diversity of environmental contaminants, such as PAHs resulted in the development of numerous analytical techniques and protocols for the extraction of these components and analysis in several samples. This systematic review article seeks to relate the extraction and preparation methods of complex samples from aquatic animals and the two main detection techniques of PAHs. For the elaboration of the research, 67 articles published between 2011 and 2021 were sought, which specifically contemplated the isolation of aquatic extracts and detection and quantification techniques of PAHs.

Advances in Chemical Analysis of Oil Spills Since the Deepwater Horizon Disaster

Analytical techniques for chemical analysis of oil, oil photochemical and biological transformation products, and dispersants and their biodegradation products benefited significantly from research following the 2010 Deepwater Horizon (DWH) disaster. Crude oil and weathered-oil matrix reference materials were developed based on the Macondo well oil and characterized for polycyclic aromatic hydrocarbons, hopanes, and steranes for use to assure and improve the quality of analytical measurements in oil spill research. Advanced gas chromatography (GC) techniques such as comprehensive two-dimensional GC (GC × GC), pyrolysis GC with mass spectrometry (MS), and GC with tandem MS (GC-MS/MS) provide a greater understanding at the molecular level of composition and complexity of oil and weathering changes. The capabilities of high-resolution MS (HRMS) were utilized to extend the analytical characterization window beyond conventional GC-based methods to include polar and high molecular mass components (>400 Da) and to provide new opportunities for discovery, characterization, and investigation of photooxidation and biotransformation products. Novel separation approaches to reduce the complexity of the oil and weathered oil prior to high-resolution MS and advanced fluorescence spectrometry have increased the information available on spilled oil and transformation products. HRMS methods were developed to achieve the required precision and sensitivity for detection of dispersants and to provide molecular-level characterization of the complex surfactants. Overall, research funding following the DWH oil spill significantly advanced and expanded the use of analytical techniques for chemical analysis to support petroleum and dispersant characterization and investigations of fate and effects of not only the DWH oil spill but future spills.

Photo-enhanced toxicity of crude oil on early developmental stages of Atlantic cod (Gadus morhua)

Photo-enhanced toxicity of crude oil is produced by exposure to ultraviolet (UV) radiation. Atlantic cod (Gadus morhua) embryos were exposed to crude oil with and without UV radiation (290-400 nm) from 3 days post fertilization (dpf) until 6 dpf. Embryos from the co-exposure experiment were continually exposed to UV radiation until hatching at 11 dpf. Differences in body burden levels and cyp1a expression in cod embryos were observed between the exposure regimes. High doses of crude oil produced increased mortality in cod co-exposed embryos, as well as craniofacial malformations and heart deformities in larvae from both experiments. A higher number of differentially expressed genes (DEGs) and pathways were revealed in the co-exposure experiment, indicating a photo-enhanced effect of crude oil toxicity. Our results provide mechanistic insights into crude oil and photo-enhanced crude oil toxicity, suggesting that UV radiation increases the toxicity of crude oil in early life stages of Atlantic cod.

Investigation of Petroleum Hydrocarbon Fingerprints of Water and Sediment Samples of the Nestos River Estuary in Northern Greece

The oil and gas industry is definitely considered the main contributor in the energy sector, acting as the lifeblood of our planet. However, environmental contamination by crude oil and petroleum products due to anthropogenic activities is of great concern. Nestos River springs from Bulgaria and has a total length of 234 km, from which 135 km belong on Greek land. It is globally recognized as nature’s miracle accommodating a variety of habitats, flora, and fauna species at the deltaic area protected by the RAMSAR Convention. In the current study, water and sediment samples from three different sites along the river course and other six sites of the delta region and the surrounding sea area were selected in order to investigate the potential environmental impact of the nearby oil and gas industry in the Prinos-Kavala basin that operates over 40 years. The samples were analyzed by fingerprinting techniques using gas chromatography-mass spectrometry. Crude oil samples and different petroleum products were also analyzed to disclose specific markers (biomarkers) that characterize the different sources of oil spills. The analytical data revealed that the distribution of biomarkers is a valuable tool in oil spill identification as well as in their correlation to suspected sources. Extract ion chromatograms of the reference samples showed significant differences in the distribution of n-alkane, isoprenoid, sterane, triterpane, and dibenzothiophene compounds. The results on the analyzed water and sediment samples bared no evidence of environmental hazards associated with the hydrocarbon exploration and production activities of the neighboring oil and gas company.

Cardiac dysfunction affects eye development and vision by reducing supply of lipids in fish

Developing organisms are especially vulnerable to environmental stressors. Crude oil exposure in early life stages of fish result in multiple functional and developmental defects, including cardiac dysfunction and abnormal and smaller eyes. Phenanthrene (Phe) has a reversible impact on cardiac function, and under exposure Phe reduces cardiac contractility. Exposure to a known L-type channel blocker, nicardipine hydrochloride (Nic) also disrupts cardiac function and creates eye deformities. We aimed to investigate whether cardiac dysfunction was the major underlying mechanism of crude oil-, Phe- and Nic-induced eye malformations. We exposed Atlantic haddock (Melanogrammus aeglefinus) early embryos to Nic and crude oil (Oil) and late embryos/early larvae to Phe exposure. All three exposures resulted in cardiac abnormalities and lead to severe, eye, jaw and spinal deformities at early larval stages. At 3 days post hatching, larvae from the exposures and corresponding controls were dissected. Eyes, trunk, head and yolk sac were subjected to lipid profiling, and eyes were also subjected to transcriptomic profiling. Among most enriched pathways in the eye transcriptomes were fatty acid metabolism, calcium signaling and phototransduction. Changes in lipid profiles and the transcriptome suggested that the dysfunctional and abnormal eyes in our exposures were due to both disruption of signaling pathways and insufficient supply of essential fatty acids and other nutrients form the yolk.

Comparison of different approaches to quantify substituted polycyclic aromatic compounds

Unlike native polycyclic aromatic hydrocarbons (PAHs), quantitation of substituted polycyclic aromatic compounds (PACs) has been a challenge in the environmental industry. The challenge can be attributed in part to the large number of theoretically possible isomers and the lack of authentic standards for quantitation. In addition, the lack of a unified approach to the quantitation of these compounds has led to poor interlaboratory accuracy. Because these compounds are often used for toxicology studies or to delineate sources and fingerprinting, it is vital that a standardized approach to quantify them is established. This study evaluated different quantitation approaches to quantify both 16 individual PACs and 32 groups/clusters of substituted PACs in three standard reference materials (SRM 1944 - New York / New Jersey waterway sediments, SRM 1597 - a coal tar sample and SRM 2779 - Gulf of Mexico crude oil). The methods employed include: (1) external calibration taking into account recovery correction factor for each analyte, (2) an average relative response factor (ARRF) of PACs obtained with a recovery correction, (3) ARRF of PACs obtained using uncorrected peak areas (i.e., no recovery correction), (4) ARRF of PACs calculated by normalization to deuterated PAHs and (5) ARRF of native PAHs to quantify substituted PACs. The evaluation of concentrations of individually substituted PACs from the different quantitative approaches compared to the certified/reference values showed that methods 1, 2 and 3 performed best. The average percentage of compounds that fell within our acceptable limit (±30%) using methods 1, 2 and 3 for SRM-1944, -1597a and -2779 was 87, 75 and 100%, respectively. Using native PAHs to quantify their substituted analogs resulted in data of the poorest quality. Irrespective of the approach used, there were significant systematic errors in measurements on clusters/groups PACs most notably C₁ and C₂-benzanthracenes/ chrysenes/triplenylenes, and C₂- and C₃-dibenzothiophenes being consistently greater than 100% of the stated value. Commerical availability of more substituted PACs will mitigate the biases associated with the quanititation of PAC clusters/groups.

Combined effects of crude oil exposure and warming on eggs and larvae of an arctic forage fish

Climate change, along with environmental pollution, can act synergistically on an organism to amplify adverse effects of exposure. The Arctic is undergoing profound climatic change and an increase in human activity, resulting in a heightened risk of accidental oil spills. Embryos and larvae of polar cod (Boreogadus saida), a key Arctic forage fish species, were exposed to low levels of crude oil concurrently with a 2.3 °C increase in water temperature. Here we show synergistic adverse effects of increased temperature and crude oil exposure on early life stages documented by an increased prevalence of malformations and mortality in exposed larvae. The combined effects of these stressors were most prevalent in the first feeding larval stages despite embryonic exposure, highlighting potential long-term consequences of exposure for survival, growth, and reproduction. Our findings suggest that a warmer Arctic with greater human activity will adversely impact early life stages of this circumpolar forage fish.

Microplastics do not increase bioaccumulation of petroleum hydrocarbons in Arctic zooplankton but trigger feeding suppression under co-exposure conditions

Arctic sea ice has alarmingly high concentrations of microplastics (MPs). Additionally, sea ice reduction in the Arctic is opening new opportunities for the oil and maritime industries, which could increase oil pollution in the region. Yet knowledge of the effects of co-exposure to MPs and crude oil on Arctic zooplankton is lacking. We tested the influence of MPs (polyethylene, 20.7 μm) on polycyclic aromatic hydrocarbon (PAH) bioaccumulation and oil toxicity in the key arctic copepod Calanus hyperboreus after exposure to oil with and without dispersant. Up to 30% of the copepods stopped feeding and fecal pellet production rates were reduced after co-exposure to oil (1 μL L^-1) and MPs (20 MPs mL^-1). The PAH body burden was ~3 times higher in feeding than in non-feeding copepods. Copepods ingested both MPs and crude oil droplets. MPs did not influence bioaccumulation of PAHs in copepods or their fecal pellets, but chemical dispersant increased bioaccumulation, especially of ≥4 ring-PAHs. Our results suggest that MPs do not act as vectors of PAHs in Arctic marine food webs after oil spills, but, at high concentrations (20 MPs mL^-1), MPs can trigger behavioral stress responses (e.g., feeding suppression) to oil pollution in zooplankton.

Determination of C0 -C9 alkyl phenols in produced-water-exposed fish eggs using gas chromatography/tandem mass spectrometry

RATIONALE

Produced water (PW) discharge from the oil and gas industry represents the largest intentional marine waste volume. Alkyl phenols (APs) are one of the main toxic component groups found in PW, with concentration of APs in discharged PW from the Norwegian Sector of the North Sea up to >16 mg/L. Several species of fish spawn in direct proximity to offshore production platforms and may be at risk of AP exposure. Therefore, a sensitive method to determine the potential for bioaccumulation of APs in fish eggs is needed.

METHODS

Fish eggs were extracted using liquid-solid extraction followed by gel permeation chromatography cleanup. Analysis was performed by gas chromatography coupled to triple quadrupole mass spectrometry. Extraction and analytical conditions were optimized for analysis of phenol and 30 APs (C₁ -C₉ ) with different degrees of branching in the alkyl chain. The method was verified and applied to analyze the body residue of APs in PW-exposed marine fish (Atlantic cod, Gadus morhua) eggs.

RESULTS

A comprehensive and sensitive method for the determination of C₀ -C₉ APs was developed. Detection limits were in the range 0.03-8 ng. Apart from a few compounds with poor recovery, the method generally provided reliable results with good precision (<15%).

CONCLUSIONS

We demonstrate the successful application of an optimized extraction method for APs in fish eggs and show first results of AP accumulation in cod embryos exposed to PW in the laboratory.

Environmental effects of offshore produced water discharges: A review focused on the Norwegian continental shelf

Produced water (PW), a large byproduct of offshore oil and gas extraction, is reinjected to formations or discharged to the sea after treatment. The discharges contain dispersed crude oil, polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), metals, and many other constituents of environmental relevance. Risk-based regulation, greener offshore chemicals and improved cleaning systems have reduced environmental risks of PW discharges, but PW is still the largest operational source of oil pollution to the sea from the offshore petroleum industry. Monitoring surveys find detectable exposures in caged mussel and fish several km downstream from PW outfalls, but biomarkers indicate only mild acute effects in these sentinels. On the other hand, increased concentrations of DNA adducts are found repeatedly in benthic fish populations, especially in haddock. It is uncertain whether increased adducts could be a long-term effect of sediment contamination due to ongoing PW discharges, or earlier discharges of oil-containing drilling waste. Another concern is uncertainty regarding the possible effect of PW discharges in the sub-Arctic Southern Barents Sea. So far, research suggests that sub-arctic species are largely comparable to temperate species in their sensitivity to PW exposure. Larval deformities and cardiac toxicity in fish early life stages are among the biomarkers and adverse outcome pathways that currently receive much attention in PW effect research. Herein, we summarize the accumulated ecotoxicological knowledge of offshore PW discharges and highlight some key remaining knowledge needs.

Polycyclic aromatic compounds (PACs) in the Canadian environment: A review of sampling techniques, strategies and instrumentation

A wide variety of sampling techniques and strategies are needed to analyze polycyclic aromatic compounds (PACs) and interpret their distributions in various environmental media (i.e., air, water, snow, soils, sediments, peat and biological material). In this review, we provide a summary of commonly employed sampling methods and strategies, as well as a discussion of routine and innovative approaches used to quantify and characterize PACs in frequently targeted environmental samples, with specific examples and applications in Canadian investigations. The pros and cons of different analytical techniques, including gas chromatography - flame ionization detection (GC-FID), GC low-resolution mass spectrometry (GC-LRMS), high performance liquid chromatography (HPLC) with ultraviolet, fluorescence or MS detection, GC high-resolution MS (GC-HRMS) and compound-specific stable (δ¹³C, δ²H) and radiocarbon (Δ¹⁴C) isotope analysis are considered. Using as an example research carried out in Canada's Athabasca oil sands region (AOSR), where alkylated polycyclic aromatic hydrocarbons and sulfur-containing dibenzothiophenes are frequently targeted, the need to move beyond the standard list of sixteen EPA priority PAHs and for adoption of an AOSR bitumen PAC reference standard are highlighted.

DNA damage and health effects in juvenile haddock (Melanogrammus aeglefinus) exposed to PAHs associated with oil-polluted sediment or produced water

The research objective was to study the presence of DNA damages in haddock exposed to petrogenic or pyrogenic polyaromatic hydrocarbons (PAHs) from different sources: 1) extracts of oil produced water (PW), dominated by 2-ring PAHs; 2) distillation fractions of crude oil (representing oil-based drilling mud), dominated by 3-ring PAHs; 3) heavy pyrogenic PAHs, mixture of 4/5/6-ring PAHs. The biological effect of the different PAH sources was studied by feeding juvenile haddock with low doses of PAHs (0.3-0.7 mg PAH/kg fish/day) for two months, followed by a two-months recovery. In addition to the oral exposure, a group of fish was exposed to 12 single compounds of PAHs (4/5/6-ring) via intraperitoneal injection. The main endpoint was the analysis of hepatic and intestinal DNA adducts. In addition, PAH burden in liver, bile metabolites, gene and protein expression of CYP1A, GST activity, lipid peroxidation, skeletal deformities and histopathology of livers were evaluated. Juvenile haddock responded quickly to both intraperitoneal injection and oral exposure of 4/5/6-ring PAHs. High levels of DNA adducts were detected in livers three days after the dose of the single compound exposure. Fish had also high levels of DNA adducts in liver after being fed with extracts dominated by 2-ring PAHs (a PW exposure scenario) and 3-ring PAHs (simulating an oil exposure scenario). Elevated levels of DNA adducts were observed in the liver of all exposed groups after the 2 months of recovery. High levels of DNA adduct were found also in the intestines of individuals exposed to oil or heavy PAHs, but not in the PW or control groups. This suggests that the intestinal barrier is very important for detoxification of orally exposures of PAHs.

Expression and localization of the aryl hydrocarbon receptors and cytochrome P450 1A during early development of Atlantic cod (Gadus morhua)

The aryl hydrocarbon receptor (Ahr) is a ligand-activated transcription factor that mediates the toxicity of dioxins and dioxin-like compounds (DLCs) in vertebrates. Two clades of the Ahr family exist in teleosts (Ahr1 and Ahr2), and it has been demonstrated that Ahr2 is the main protein involved in mediating the toxicity of dioxins and DLCs in most teleost species. Recently, we characterized the Atlantic cod (Gadus morhua) Ahr1a and Ahr2a receptors. To further explore a possible subfunction partitioning of Ahr1a and Ahr2a in Atlantic cod we have mapped the expression and localization of ahr1a and ahr2a in early developmental stages. Atlantic cod embryos were continuously exposed in a passive-dosing exposure system to the Ahr agonist, benzo[a]pyrene (B[a]P), from five days post fertilization (dpf) until three days post hatching (dph). Expression of ahr1a, ahr2a, and the Ahr-target genes, cyp1a and ahrrb, was assessed in embryos (8 dpf and 10 dpf) and larvae (3 dph) with quantitative real-time PCR analyses (qPCR), while in situ hybridization was used to assess the localization of expression of ahr1a, ahr2a and cyp1a. Quantitative measurements showed an increased cyp1a expression in B[a]P-exposed samples at all sampling points, and for ahr2a at 10 dpf, confirming the activation of the Ahr-signalling pathway. Furthermore, B[a]P strongly induced ahr2a and cyp1a expression in the cardiovascular system and skin, respectively, of embryos and larvae. Induced expression of both ahr2a and cyp1a was also revealed in the liver of B[a]P-exposed larvae. Our results suggest that Ahr2a is the major subtype involved in mediating responses to B[a]P in early developmental stages of Atlantic cod, which involves transcriptional regulation of biotransformation genes, such as cyp1a. The focused expression of ahr1a in the eye of embryos and larvae, and the presence of ahr2a transcripts in the jaws and fin nodes, further indicate evolved specialized roles of the two Ahrs in ontogenesis.

Understanding the relative performance of SCAN, SIM, PMRM and MRM methods for quantifying polycyclic aromatic hydrocarbons in crude oil samples

RATIONALE

Polycyclic aromatic hydrocarbons (PAHs) present in oil spill samples are analyzed by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/tandem mass spectrometry (GC/MS/MS) using four different methods: (1) full scan (SCAN), (2) selected ion monitoring (SIM), (3) multiple reaction monitoring (MRM), and (4) pseudo multiple reaction monitoring (PMRM). This study quantifies the relative performance of these methods.

METHODS

Novel experiments were designed to measure the signal-to-noise (S/N) ratios of all four methods. This was accomplished by spiking the crude oil with five deuterated PAHs (dPAHs) in two distinct ways: (1) varying the background noise by changing crude oil concentrations before spiking the samples with 1 ng/mL of dPAHs, and (2) varying the signal by spiking dPAHs concentrations of 0.5 and 5 ng/mL into a crude oil sample.

RESULTS

The MRM method is the most selective and sensitive of the four methods. It also provides the lowest limit of detection (LOD) and limit of quantitation (LOQ). MRM is the optimal approach for quantifying PAHs in complex petroleum samples containing high levels of background noise. Also, our data show that the PAHs in complex oil spill samples can be quantified by MRM without using any complicated sample preparation steps.

CONCLUSIONS

Based on our experimental data, the relative performance of the four methods used for quantifying PAHs in crude oil samples can be ranked as MRM > PMRM > SIM > SCAN.

The use of PAH, metabolite and lipid profiling to assess exposure and effects of produced water discharges on pelagic copepods

Several laboratory studies have demonstrated that exposure to oil components cause toxicity to copepods, however, this has never been shown in natural populations of copepods. In the present study, we sampled copepods in an area of the North Sea with high density of oil production platforms discharging produced water. Environmental modelling was used to predict produced water and copepod trajectories prior to copepod sampling in situ. To maximise output from a minimal number of field samples, a novel and combined methodology was developed to allow exploitation of the same extract for several purposes; contaminant body burden, lipidomics, and metabolomics analysis. PAH body burdens were low compared to laboratory experiments where correlations between PAH body burden and acute toxicity, reproduction and molecular endpoints had been established. Still, station-specific PAH profiles strongly indicated copepod exposure to PW. NMR metabolomics, focusing on water-soluble metabolites, suggested no correlation between metabolites and stations. Interestingly, lipidomics analyses suggested site-specific fingerprints and profiles displayed for acyl-glycerols and wax esters. Potential effects of produced water exposure on lipid metabolism in copepods cannot be ruled out and deserves more attention. Our study exemplifies the importance of incorporating novel and improved analytical methodologies in environmental monitoring.

Dispersant Enhances Hydrocarbon Degradation and Alters the Structure of Metabolically Active Microbial Communities in Shallow Seawater From the Northeastern Gulf of Mexico

Dispersant application is a primary emergency oil spill response strategy and yet the efficacy and unintended consequences of this approach in marine ecosystems remain controversial. To address these uncertainties, ex situ incubations were conducted to quantify the impact of dispersant on petroleum hydrocarbon (PHC) biodegradation rates and microbial community structure at as close as realistically possible to approximated in situ conditions [2 ppm v/v oil with or without dispersant, at a dispersant to oil ratio (DOR) of 1:15] in surface seawater. Biodegradation rates were not substantially affected by dispersant application at low mixing conditions, while under completely dispersed conditions, biodegradation was substantially enhanced, decreasing the overall half-life of total PHC compounds from 15.4 to 8.8 days. While microbial respiration and growth were not substantially altered by dispersant treatment, RNA analysis revealed that dispersant application resulted in pronounced changes to the composition of metabolically active microbial communities, and the abundance of nitrogen-fixing prokaryotes, as determined by qPCR of nitrogenase (nifH) genes, showed a large increase. While the Gammaproteobacteria were enriched in all treatments, the Betaproteobacteria and different families of Alphaproteobacteria predominated in the oil and dispersant treatment, respectively. Results show that mixing conditions regulate the efficacy of dispersant application in an oil slick, and the quantitative increase in the nitrogen-fixing microbial community indicates a selection pressure for nitrogen fixation in response to a readily biodegradable, nitrogen-poor substrate.

Ecotoxicological benthic impacts of experimental oil-contaminated marine snow deposition

Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) can pose serious threats to the marine benthic ecosystem as it results in a deposition of oil contaminated marine snow on the sediment surface. In a microcosm experiment we investigated the effects of oil in combination with artificial marine snow or kaolin clay on two benthic invertebrate species and benthic meiofauna. The amphipod showed a dose-dependent decrease in survival for both oil-contaminated clay and oil-contaminated marine snow. The gastropod was only affected by the highest concentration of oil-contaminated marine snow and had internal concentrations of PAHs with a similar distribution as oil-contaminated marine snow. Benthic copepods showed higher survival in presence of marine snow. This study revealed that marine snow on the sediment after oil spills affects organisms in a trait-dependent way and that it can be a vector for introducing oil into the food web.

Decadal Assessment of Polycyclic Aromatic Hydrocarbons in Mesopelagic Fishes from the Gulf of Mexico Reveals Exposure to Oil-Derived Sources

This study characterizes a decadal assessment of polycyclic aromatic hydrocarbons (PAHs) in the muscle tissues of mesopelagic fish species as indicators of the environmental health of the Gulf of Mexico (GoM) deep-pelagic ecosystem. Mesopelagic fishes were collected prior to the Deepwater Horizon (DWH) oil spill (2007), immediately post-spill (2010), 1 year after the spill (2011), and 5-6 years post-spill (2015-2016) to assess if the mesopelagic ecosystem was exposed to, and retained, PAH compounds from the DWH spill. Results indicated that a 7- to 10-fold increase in PAHs in fish muscle tissues occurred in 2010-2011 (4972 ± 1477 ng/g) compared to 2007 (630 ± 236 ng/g). In 2015-2016, PAH concentrations decreased close to the levels measured in 2007 samples (827 ± 138 ng/g); however, the composition of PAHs still resembles a petrogenic source similar to samples collected in 2010-2011. PAH composition in muscle samples indicated that natural sources (e.g., Mississippi River and natural seeps) or spatial variability within the GoM do not explain the temporal variability of PAHs observed from 2007 to 2016. Furthermore, analysis of different fish tissues indicated the dietary intake and maternal transfer of PAHs as the primary mechanisms for bioaccumulation in 2015-2016, explaining the elevated levels and composition of PAHs in ovarian eggs.

Validation of a simultaneous method for determining polycyclic aromatic compounds and alkylated isomers in biota

RATIONALE

There is a need for a validated method to improve detection limits and simultaneously quantify polycyclic aromatic compounds (PACs, both parent and alkylated homologues) in biota by gas chromatography/tandem mass spectrometry because of their environmental significance. The validation of the method was performed in accordance to the Eurachem Guide to Quality in Analytical Chemistry.

METHODS

Gas chromatography coupled with a triple quadrupole mass spectrometer used in multiple reaction monitoring (MRM) mode was used for detection and quantification. Retention time windows and selective MRM ion transitions were optimized for a suite of PACs. The developed method was validated by comparing our measurements made on a reference material of freeze-dried mussel tissue (Mytilus edulis) with the certified values.

RESULTS

Linearity was observed between 10-1000 pg/μL (PAHs) and 2-500 pg/μL (alkyl-PACs including S-based PACs). The overall mean (±SD) for the limits of detection of 43 PACs studied were 0.305 ± 0.276 and 2.69 ± 1.10 ng/g, respectively. For the 14 certified target analytes, the percent relative error ranged from 1.3 to 33%. With the exception of benzo(a)pyrene, the between-day and within-day repeatability for all target analytes was lower than 15% RSD.

CONCLUSIONS

This is the first report of a fully validated method to simultaneously quantify PACs in biota performed in an ISO accredited laboratory.

Application of enhanced gas chromatography/triple quadrupole mass spectrometry for monitoring petroleum weathering and forensic source fingerprinting in samples impacted by the Deepwater Horizon oil spill

Accurate characterization of petroleum hydrocarbons in complex and weathered oil residues is analytically challenging. This is primarily due to chemical compositional complexity of both the oil residues and environmental matrices, and the lack of instrumental selectivity due to co-elution of interferences with the target analytes. To overcome these analytical selectivity issues, we used an enhanced resolution gas chromatography coupled with triple quadrupole mass spectrometry in Multiple Reaction Monitoring (MRM) mode (GC/MS/MS-MRM) to eliminate interferences within the ion chromatograms of target analytes found in environmental samples. This new GC/MS/MS-MRM method was developed and used for forensic fingerprinting of deep-water and marsh sediment samples containing oily residues from the Deepwater Horizon oil spill. The results showed that the GC/MS/MS-MRM method increases selectivity, eliminates interferences, and provides more accurate quantitation and characterization of trace levels of alkyl-PAHs and biomarker compounds, from weathered oil residues in complex sample matrices. The higher selectivity of the new method, even at low detection limits, provides greater insights on isomer and homolog compositional patterns and the extent of oil weathering under various environmental conditions. The method also provides flat chromatographic baselines for accurate and unambiguous calculation of petroleum forensic biomarker compound ratios. Thus, this GC/MS/MS-MRM method can be a reliable analytical strategy for more accurate and selective trace level analyses in petroleum forensic studies, and for tacking continuous weathering of oil residues.

Oil droplet fouling and differential toxicokinetics of polycyclic aromatic hydrocarbons in embryos of Atlantic haddock and cod

The impact of crude oil pollution on early life stages (ELS) of fish, including larvae and embryos, has received considerable attention in recent years. Of the organic components present in crude oil, polycyclic aromatic hydrocarbons (PAHs) are considered the main class of compounds responsible for toxic effects in marine organisms. Although evidence suggests that they are more toxic, alkylated PAHs remain much less studied than their unsubstituted congeners. Recently, it was established that embryos of Atlantic haddock (Melanogrammus aeglefinus) are particularly sensitive to dispersed crude oil, and it was hypothesized that this was caused by direct interaction with crude oil droplets, which adhered to the chorion of exposed embryos. Such a phenomenon would increase the potential for uptake of less water-soluble compounds, including alkylated PAHs. In the current study, we compared the uptake of parent and alkylated PAHs in Atlantic cod (Gadus morhua) and haddock embryos exposed to dispersed crude oil at a range of environmentally relevant concentrations (10–600 μg oil/liter seawater). Although the species are biologically very similar, the cod chorion does not become fouled with oil droplets, even when the two species are exposed to dispersions of crude oil droplets under similar conditions. A close correlation between the degree of fouling and toxicological response (heart defects, craniofacial malformation) was observed. Oil droplet fouling in haddock led to both quantitative and qualitative differences in PAH uptake. Finally, kinetic data on a large suite of PAHs showed differential elimination, suggesting differential metabolism of unsubstituted versus alkylated compounds.