PAHs in high Arctic copepods Calanus hyperboreus following exposure of residues from in situ burning of oil spill.

In situ burning of marine oil spills reduces the total amount of oil in the environment, but a negative side effect may be the generation of environmentally hazardous polycyclic aromatic hydrocarbons (PAHs) that may pose a risk for bioaccumulation, particularly in organisms having a high lipid content. In this study uptake of PAHs from oil and burn residue were examined in the high arctic copepod Calanus hyperboreus. A major part of the low ring number petrogenic PAHs in the oil was removed during burning and relative higher concentrations of pyrogenic high ring number PAHs was found in the burn residue. This suggests that burning markedly reduces the general PAH exposure load. Furthermore, the pyrogenic PAHs generated during the burn were not bioconcentrated to quantifiable levels in the copepods. We conclude that in situ burning can mitigate the potential risk of PAH uptake for copepods and other pelagic organisms in the marine environment as the pyrogenic PAHs only pose low risk for uptake from the water by the copepods and other pelagic organisms.

Coastline in-situ burning of oil spills in the Arctic. Studies of the environmental impacts on the littoral zone community.

In-situ burning (ISB) has been an oil combat technique studied since the 1950s. However, burning of the oil on the sea surface along the coastline, coastline ISB (cISB), is novel and was tested for the first time in the Arctic along a rocky coast in the summer 2017. A light crude oil was burned and effects of the cISB operation on the littoral zone communities investigated. The impact on macroalgal vegetation and associated fauna was analysed in three littoral zone levels. The analyses revealed limited effects on the littoral community, and that variation between sample plots and years in macroalgal biomass and coverage, as well as fauna biomass and abundance was higher than the impact from cISB. Therefore, it is concluded that cISB in the Arctic along a rocky shore may be an oil spill response option with relatively low environmental side effects for the specific oil type used.

Comparative toxicity assessment of in situ burn residues to initial and dispersed heavy fuel oil using zebrafish embryos as test organisms.

In situ burning (ISB) is discussed to be one of the most suitable response strategies to combat oil spills in extreme conditions. After burning, a highly viscous and sticky residue is left and may over time pose a risk of exposing aquatic biota to toxic oil compounds. Scientific information about the impact of burn residues on the environment is scarce. In this context, a comprehensive ISB field experiment with approx. 1000L IFO 180 was conducted in a fjord in Greenland. The present study investigated the toxicity of collected ISB residues to early life stages of zebrafish (Danio rerio) as a model for potentially exposed pelagic organisms. The toxicity of ISB residues on zebrafish embryos was compared with the toxicity of the initial (unweathered) IFO 180 and chemically dispersed IFO 180. Morphological malformations, hatching success, swimming behavior, and biomarkers for exposure (CYP1A activity, AChE inhibition) were evaluated in order to cover the toxic response on different biological organization levels. Across all endpoints, ISB residues did not induce greater toxicity in zebrafish embryos compared with the initial oil. The application of a chemical dispersant increased the acute toxicity most likely due to a higher bioavailability of dissolved and particulate oil components. The results provide insight into the adverse effects of ISB residues on sensitive life stages of fish in comparison with chemical dispersant application.

Biodegradation of marine oil spills in the Arctic with a Greenland perspective.

New economic developments in the Arctic, such as shipping and oil exploitation, bring along unprecedented risks of marine oil spills. Microorganisms have played a central role in degrading and reducing the impact of the spilled oil during past oil disasters. However, in the Arctic, and in particular in its pristine areas, the self-cleaning capacity and biodegradation potential of the natural microbial communities have yet to be uncovered. This review compiles and investigates the current knowledge with respect to environmental parameters and biochemical constraints that control oil biodegradation in the Arctic. Hereby, seawaters off Greenland are considered as a case study. Key factors for biodegradation include the bioavailability of hydrocarbons, the presence of hydrocarbon-degrading bacteria and the availability of nutrients. We show how these key factors may be influenced by the physical oceanographic conditions in seawaters off Greenland and other environmental parameters including low temperature, sea ice, sunlight regime, suspended sediment plumes and phytoplankton blooms that characterize the Arctic. Based on the acquired insights, a first qualitative assessment of the biodegradation potential in seawaters off Greenland is presented. In addition to the most apparent Arctic characteristics, such as low temperature and sea ice, the impact of typical Arctic features such as the oligotrophic environment, poor microbial adaptation to hydrocarbon degradation, mixing of stratified water masses, and massive phytoplankton blooms and suspended sediment plumes merit to be topics of future investigation.

Effectiveness of a chemical herder in association with in-situ burning of oil spills in ice-infested water.

The average herded slick thickness, surface distribution and burning efficiency of a light crude oil were studied in ice-infested water to determine the effectiveness of a chemical herder in facilitating the in-situ burning of oil. Experiments were performed in a small scale (1.0m2) and an intermediate scale (19m2) setup with open water and 3/10, 5/10 and 7/10 brash ice coverages. The herded slick thicknesses (3-8mm) were ignitable in each experiment. The presence of ice caused fracturing of the oil during the herding process, which reduced the size of the herded slicks and, as a consequence, their ignitability, which in turn decreased the burning efficiency. Burning efficiencies relative to the ignited fraction of the oil were in the expected range (42-86%). This shows that the herder will be an effective tool for in-situ burning of oil when the ignitability issues due to fracturing of the oil are resolved.

Suitability of oil bioremediation in an Artic soil using surplus heating from an incineration facility.

A 168-day period field study, carried out in Sisimiut, Greenland, assessed the potential to enhance soil remediation with the surplus heating from an incineration facility. This approach searches a feasible ex situ remediation process that could be extended throughout the year with low costs. Individual and synergistic effects of biostimulation were also tested, in parallel. An interim evaluation at the end of the first 42 days showed that biostimulation and active heating, as separate treatments, enhanced petroleum hydrocarbon (PHC) removal compared to natural attenuation. The coupling of both technologies was even more effective, corroborating the benefits of both techniques in a remediation strategy. However, between day 42 and day 168, there was an opposite remediation trend with all treatments suggesting a stabilization except for natural attenuation, where PHC values continued to decrease. This enforces the "self-purification" capacity of the system, even at low temperatures. Coupling biostimulation with active heating was the best approach for PHC removal, namely for a short period of time (42 days). The proposed remediation scheme can be considered a reliable option for faster PHC removal with low maintenance and using "waste heating" from an incineration facility.

Composition of in situ burn residue as a function of weathering conditions.

Troll B crude oil was weathered under Arctic conditions with different ice coverage: open water, 50% ice and 90% ice. Samples (100 mL) were taken during the experiment and tested for ignitability in a burning cell. From each burning a residue sample was taken for analysis. The burning process removed the light compounds eluting before C13. No effect from the prior weathering time or the different ice coverage was seen in the burn residue composition. The content of selected Poly Aromatic Hydrocarbons (PAHs) was determined and it was noted that the concentration of PAHs with more than 4 rings were increased. The source origin of the PAHs was investigated by use of relative ratios of PAH isomers and indicated that some formation of PAHs was additionally taking place during burning.

Measuring ignitability for in situ burning of oil spills weathered under Arctic conditions: from laboratory studies to large-scale field experiments.

This paper compares the ignitability of Troll B crude oil weathered under simulated Arctic conditions (0%, 50% and 90% ice cover). The experiments were performed in different scales at SINTEF's laboratories in Trondheim, field research station on Svalbard and in broken ice (70-90% ice cover) in the Barents Sea. Samples from the weathering experiments were tested for ignitability using the same laboratory burning cell. The measured ignitability from the experiments in these different scales showed a good agreement for samples with similar weathering. The ice conditions clearly affected the weathering process, and 70% ice or more reduces the weathering and allows a longer time window for in situ burning. The results from the Barents Sea revealed that weathering and ignitability can vary within an oil slick. This field use of the burning cell demonstrated that it can be used as an operational tool to monitor the ignitability of oil spills.