Alaska North Slope Crude Oil Research Articles

Sediment ballast accelerates sinking of Alaska North Slope crude oil measured ex situ with surface water from Cook Inlet

Oil spilled into the ocean interacts with suspended matter forming aggregates that transport oil into subsurface layers and towards the bottom. We conducted a series of laboratory experiments to explore aggregation of oil with natural phytoplankton assemblages from Cook Inlet, Alaska at three times during a spring bloom. Oil and phytoplankton formed marine oil snow (MOS) that remained positively buoyant with a small fraction of MOS sinking to the bottom of our experimental bottles. Seawater treatments amended with suspended sediments formed oil-mineral aggregates (OMAs) with an oil capacity similar to MOS (∼20% of aggregate area was covered with oil). OMAs accelerated oil sedimentation in our bottles relative to MOS sedimentation underlining the significance of suspended matter as ballast for sinking oil. Our results reveal potential transport mechanisms of oil in Cook Inlet which apply to other coastal systems with high productivity and sediment loads.

Fragmentation of chemically herded oil slicks by multiple obstacles

Chemical herders contract oil slicks floating on the water surface and will likely be a useful tool at high latitudes for condensing oil spills in ice laden waters for in situ burning. However, floating ice and other obstacles on the sea surface fracture the contracting oil slick and trap patches of oil, thus degrading herder performance and burning efficiency. Using Alaska North Slope crude oil and the herding agent OP-40, we performed laboratory scale experiments to investigate how a contracting oil slick interacts with multiple obstacles arranged at different packing densities and with a bottleneck-type gap between obstacles, with a focus on the fluid mechanics of this interaction. The surface and spatial distribution of the herded oil slick is optically measured over time, and particle image velocimetry is used to measure the oil slick flow around the obstacles. Obstacle groups containing large numbers of tightly packed obstacles acted collectively to trap large amounts of oil while widely spaced obstacles that are fewer in number retained smaller individual tails of oil that then break up via capillary instability. Small bottlenecks delayed the contraction of the herded oil slick and resulted in a jet of herder penetrating downstream of the gap whereas wider bottlenecks allowed faster contraction and thus more fragmentation of the herded slick. These results provided a greater understanding of how a contracting fluid film on the water surface interacts with and is fragmented by different types of obstacles and provide a foundation for future modeling efforts to better understand ice-herder-oil interactions.

Is there evidence of mild explosive behavior in Alaska North Slope crude oil prices?

Alaska has long been important to U.S. oil production. With the sixth largest amount of proven reserves of any state and >95% of oil production occurring on the North Slope, Alaska will continue to be an important factor in U.S. energy production. Given the importance of the North Slope crude oil to West Coast refineries, it is surprising that very few studies have investigated the prevailing price of crude oil from the North Slope: the Alaska North Slope West Coast price (ANS). This study provides evidence of mildly explosive behavior in the time series of ANS price relative to the consumer price level, Alaska oil production, and a measure of oil stocks by utilizing the recursive generalized supremum Augmented Dickey-Fuller of Phillips, Shi, and Yu (2015). The sample period spans from May 1987 until September 2020 and we find evidence of mild explosive behavior prior to and during the 2007–2009 recession. Our findings are consistent with others who found mildly explosive behavior in other oil prices during the same period.

An experimental study of oil slick contraction by chemical herders and fragmentation by obstacles

Chemical herders are a promising technique for treatment of oil spills in icy waters at high latitudes. However, obstacles on the water surface such as floating ice affects or interferes with all spill response countermeasures including chemical herder operations by fracturing the contracting oil slick and trapping small oil patches. Here we experimentally investigate the fluid dynamics of oil slick contraction and the interaction of the contracting oil slick with single obstacles of different shapes and sizes in a laboratory scale basin using Alaska North Slope crude oil and OP-40 herding agent. Oil slick area and thickness, oil-herder interface contraction speed, and the spatial distribution of the slick were optically measured over time, and particle image velocimetry (PIV) was used to measure the flow of the oil slick around the obstacles. For all obstacle sizes and shapes, an oil tail in the obstacle wake was generated as the oil-herder interface passed, which subsequently fractured by a capillary-type instability. Larger and less streamlined obstacles retained greater amounts of oil in these tails. In addition, a widely used theoretical thin film spreading model was successfully used to describe the spreading of the chemical herder against the oil slick at equilibrium. These results provide a foundation for future investigation of synergistic trapping of oil by multiple obstacles as would be seen in the field.

A cross-comparison of biosurfactants as marine oil spill dispersants: Governing factors, synergetic effects and fates

Biosurfactant-based dispersants (BBDs) may be more effective, cost-efficient and environmentally friendly than dispersants currently used for oil spill response. An improved understanding of BBD performance is needed to advance their development and commercial use. In this study, the ability of four BBDs, i.e. sufactins, trehalose lipids, rhamnolipids and exmulsins, alone and as various combinations to disperse Arabian light crude oil and weathered Alaska North Slope crude oil was compared to a widely used commercial oil dispersant (Corexit 9500A). Surfactin and trehalose lipids, which have balanced surface activity/emulsification ability, showed dispersion efficacy comparable to Corexit 9500A. Rhamnolipids (primarily a surface-active agent) and exmulsins (primarily an emulsifier) when used alone had significantly lower efficacy. However, blends of these surfactants had excellent dispersion performance because of synergistic effects. Balanced surface activity and emulsification ability may be key to formulate effective BBDs. Of the BBDs evaluated, surfactins with an effective dispersant-to-oil ratio as low as 1:62.3 and trehalose lipids with high oil affinity, biodegradation rate, and low toxicity characteristics show the most promise for commercial development.

Potential Role of Marine Snow in the Fate of Spilled Oil in Cook Inlet, Alaska

ABSTRACT The objective of the research is to inform response decision-making and understanding of the potential association of spilled oil with marine snow in Cook Inlet, Alaska. While extensive research has been conducted on minerals aggregating with spilled oil, larger organic aggregates, such as marine snow, have only recently been studied as a transport mechanism. This knowledge gap in understanding the fate of oil was highlighted as part of the Gulf of Mexico Research Initiative (GoMRI) following the Deepwater Horizon (DWH) spill. It was determined that significant percentages of spilled oil reached the seafloor as a result of association with marine snow during both DWH and the Ixtoc 1 blowouts. As development of oil resources continues in Alaska and the Arctic, marine snow is a significant oil exposure pathway that must be considered during oil spill response. In parallel with a corresponding sedimentation study, input from local, federal and industry experts was used to develop laboratory scale oil exposure experiments to evaluate the potential for oil-marine snow aggregate formation in Cook Inlet. Roller-bottle experiments were conducted from May to July 2019 to assess the interactions between a 5 μm sheen of Alaska North Slope crude oil and Cook Inlet surface water. Aggregate formation was documented and sinking flocs were observed and analyzed with fluorescence microscopy to estimate oil content. The total oil volumes estimated in aggregates were between 0.01 to 0.4 μl. Estimates of total oil volume associated with the aggregates ranged from 0.6 to 9.3 % ± 1.4% of the total oil volume (80 μl) that was added to the bottles. The incorporation of spilled oil in surface forming aggregates will contribute to understanding fate and response implications in Cook Inlet and other northern regions at risk of spilled oil entering the benthic food web via association with sinking marine snow.

Characterizing Dispersion Effectiveness at Varying Salinities

ABSTRACT Chemical dispersant formulations typically provide maximum oil dispersion in waters between 30–40 ppt (parts per thousand) salt content, which encompasses typical ocean salinity (~34 ppt). As a result, most laboratory studies of oil dispersion effectiveness (DE) are conducted at low to average ocean salinity. Ocean salinity can vary locally from below 20 ppt during ice and snow melt, to extremely high (over 100 ppt) during freeze up periods or within natural brine pools in deeper waters. In this study, the influence of salinity on DE was evaluated using the baffled flask test (BFT) at a dispersant-to-oil ratio (DOR) of 1:25. Benchtop experiments were conducted with Alaskan North Slope (ANS) crude oil in the presence or absence of chemical dispersant at 5 and 25°C and varying salinities (0.2 to 125 ppt). In addition to DE as determined by BFT, oil droplet size distribution (DSD) and fluorescence intensity was measured via a LISST-100X particle size analyzer (Sequoia Scientific, Inc., Bellevue, WA) and ECO fluorometer (Sea Bird - WET Labs, Inc.; Philomath, OR), respectively. Results indicate that in the presence of dispersant, maximum DE occurred at 25ppt, and decreases above and below this salinity. Concentration of small droplets (<10 μm) was twice as high at 35ppt than at the other salinities in the presence of dispersant at 25°C. Treatments without dispersant did not vary significantly as a function of salinity. Flume tank experiments over a range of salinities support the lab scale results of DSD. These results provide a more comprehensive picture pertaining to the influence of salinity on dispersant usage at high salinities.

Comparison of particulate-matter emissions from liquid-fueled pool fires and fire whirls

Abstract In-situ burning (ISB) is one of the most effective means of removing oil spilled over open water. While current ISB practices can eliminate a large fraction of the spilled oil, they still result in significant airborne emissions of particulate matter. ISBs are classified as large, free-buoyant pool fires, from which black smoke consisting of particulate matter (PM, soot) emanates as a plume. An experimental investigation of soot emissions from pool fires (PF) and fire whirls (FW) was conducted using liquid hydrocarbon fuels, n-heptane and Alaska North Slope (ANS) crude oil, in fuel pools 10 − 70 cm in diameter. Burning attributes such as burning rate, fuel-consumption efficiency, and emissions of PM, unburned hydrocarbons, carbon dioxide, and oxygen consumption were measured. For both fuels and all pool diameters, compared to PFs, FWs consumed fuel at a higher rate, had lower post-combustion residual mass and PM emission rates. Collectively, these resulted in consistently lower PM emission factors (EF PM ) for FWs at all scales. For FWs, EF PM decreased linearly with a nondimensional quantity defined as the ratio of inverse Rossby number to nondimensional heat-release rate. These results show that the addition of ambient circulation to free-burning PFs to form FWs can increase burning efficiency, reducing both burning duration and EF PM across length scales. The reduction in EF PM with increasing influence of circulation is attributed to a feedback loop of higher temperatures, heat feedback, burning rate and air-entrainment velocity, which in turn contributes to maintaining the structure of a FW. Boilover was observed for fires formed with ANS crude oil at the 70 cm scale, although the overall EF PM was not affected significantly. This investigation presents a foundation to evaluate the detailed mechanisms further, such that appropriate configurations can be developed help minimize the environmental impact of ISBs.

Crude oil exposure reduces ice algal growth in a sea-ice mesocosm experiment

Oil production in Arctic ice-covered areas poses a risk for pollution of the ecosystem including that within the brine channel network of sea ice. Sea-ice autotrophs contribute substantially to Arctic primary production, but are inherently difficult to test for oil exposure responses in situ. This study had two objectives, first, we developed a suitable lab-based mesocosm system, second, we tested oil effects on sea-ice algae. Specifically, we investigated if Alaska North Slope crude oil exposure reduces ice algal abundance, biomass and concentration of extracellular polymeric substances (EPS) using indoor ice tanks over a 10-day exposure period. Six tanks in one cold room were used in pairs for the following treatments: (1) control, (2) oil release as a layer under ice and (3) release of dispersed oil. All tanks were inoculated with sea-ice microbial communities collected from Utqiaġvik, Alaska. After 10 days of exposure, the abundance of algae, dominated by the pennate diatom genus Nitzschia, and the concentrations of EPS and chlorophyll a were significantly lower in the oiled treatments compared to the control. We suggest light attenuation by the oil, reduced algal mobility, and oil toxicity as causes for this reduction. Observed changes in cell fluorescence characteristics based on DNA staining could be linked to the oil exposure and could provide a new tool for assessment of toxicity in microalgae.

The sensitivity of the deepsea species northern shrimp (Pandalus borealis) and the cold-water coral (Lophelia pertusa) to oil-associated aromatic compounds, dispersant, and Alaskan North Slope crude oil

This study investigated the sensitivity of two deepsea species using mortality of northern shrimp (Pandalus borealis) and polyp activity of stony coral (Lophelia pertusa) to dispersant, Corexit 9500 and aromatic hydrocarbons (toluene, 2-methylnaphthalene, phenanthrene) in 96-h tests. Resulting hydrocarbon toxicity data were fit to the Target Lipid Model to generate predictive models and determine species sensitivity. Toxicity of chemically enhanced water accommodated fractions of Alaskan North Slope crude oil (ANS-oil) was also investigated with shrimp using nominal loading, total petroleum hydrocarbons and biomimetic extraction (BE) as oil exposure metrics. Coral were more sensitive to dispersant than shrimp while similar sensitivity was observed for hydrocarbons. Study and literature findings indicate deepsea species exhibit acute sensitivities to dispersant, hydrocarbons and oil that are comparable to pelagic species. Results support use of passive sampling methods to quantify dissolved oil for interpreting oil toxicity tests and suggest models for predicting time-dependence of toxicity warrant re-evaluation.

Microbial eco-physiological strategies for salinity-mediated crude oil biodegradation

Salinity variability strongly affects the behaviors of oil degrading bacteria for spilled oil biodegradation in the marine environment. However, limited studies explored the strategies of microbes on salinity-mediated crude oil biodegradation. In this study, a halotolerant bio-emulsifier producer, Exiguobacterium sp. N41P, was examined as a model strain for Alaska North Slope (ANS) crude oil (0.5%, v/v) biodegradation. Results indicated that Exiguobacterium sp. N41P could tolerant a wide range of salinity (0–120 g/L NaCl) and achieve the highest degradation efficiency under the salinity of 15 g/L NaCl due to the highest biofilm formation ability. Moreover, increased salinity induced decreased cell surface hydrophobicity and a migration of microbial growth from oil phase to aqueous phase, leading to limited bio-emulsifier productivity and depressed degradation of insoluble long-chain n-alkanes while enhancing the degradation of relative soluble naphthalene. Research findings illustrated the microbial eco-physiological mechanism for spilled oil biodegradation under diverse salinities and advanced the understanding of sophisticated marine crude oil biodegradation process.

Long-Term Ecological Impacts from Oil Spills: Comparison of Exxon Valdez, Hebei Spirit, and Deepwater Horizon.

The long-term ecological impacts of the Exxon Valdez oil spill (EVOS) are compared to two extensively studied and more recent large spills: Deepwater Horizon (DWH) and the Hebei Spirit oil spill (HSOS). Each of the three spills differed in magnitude and duration of oil released, environmental conditions, ecological communities, response and clean up measures, and ecological recovery. The EVOS began on March 24, 1989, and released 40.8 million liters of Alaska North Slope crude oil into the cold, nearly pristine environment of Prince William Sound, Alaska. EVOS oiled wildlife and rocky intertidal shorelines and exposed early life stages of fish to embryotoxic levels of polycyclic aromatic hydrocarbons (PAH). Long-term impacts following EVOS were observed on seabirds, sea otters, killer whales, and subtidal communities. The DWH spill began on April 20, 2010, and released 507 million liters of light Louisiana crude oil from 1600 m on the ocean floor into the Gulf of Mexico over an 87-day period. The DWH spill exposed a diversity of complex aquatic communities in the deep ocean, offshore pelagic areas, and coastal environments to petroleum hydrocarbons. Large-scale persistent ecological effects included impacts to deep ocean corals, failed recruitment of oysters over multiple years, damage to coastal wetlands, and reduced dolphin, sea turtle, and seabird populations. The HSOS began on December 7, 2007, and released approximately 13 million liters of Middle East crude oils into ecologically sensitive areas of the Taean area of western Korea. Environmental conditions and the extensive initial cleanup of HSOS oil stranded on shorelines limited the long-term impacts to changes in composition and abundance of intertidal benthic communities. Comparisons of EVOS, DWH, and HSOS show the importance and complexity of the interactions among the environment, oil spill dynamics, affected ecological systems, and response actions.

Enhanced Oil Spill Clean-Up Using Immersed Thermally Conductive Objects

A method for rapid burning of hazardous oil spills on water is investigated with the ultimate goal of designing a burner for faster clean-up of hazardous spills in offshore and other remote environments. A thermally conductive object, which comprises of a 0.25 cm thick copper porous mesh, with or without conical copper coils, is used. The influence of this object on the burning rate of an Alaska North Slope crude oil slick (1 cm thick) on saline water is studied. For the mesh-alone case, heat from flame is transferred to the mesh, which rapidly gets heated up and transmits the heat to the oil slick. This heat transfer is much higher than that in the baseline case. In the case with conical coils, which are engulfed in the flame, the heated up coils transfer the heat to the copper mesh more effectively. Thus, the object enhances the mass burning rate. Experimental results reveal that the copper mesh reaches a temperature higher than the boiling point of the oil, such that onset of nucleate boiling is possible. The mesh-coil system is able to burn thin slick of oil resting on water achieving an efficiency of ~ 400% above baseline. A simple integral model is also proposed to predict the temperature profiles in mesh, oil, and water layers. The predicted temperature profiles show good agreement with the experimental results. A parametric study using the integral model is also reported. The model can be used as a guideline to optimize the mesh porosity and thickness for different hazardous spill scenarios.

Practical Oil Spill Recovery by a Combination of Polyolefin Absorbent and Mechanical Skimmer

The objective of this research is to develop a practical and efficient oil recovery method that can be applied in large-scale crude oil spills in open water. The method is centered on a newly developed polyolefin oil superabsorbent, called “i-Petrogel”, in conjunction with existing mechanical (skimmer) recovery method. The i-Petrogel absorbent can be produced in large scale (>90 kg in our laboratory) by mixing two polyolefin polymers, including a semicrystalline linear low-density polyethylene (LLDPE) thermoplastic and a thermally cross-linkable poly(1-decene-co-divinylbenzene) (D-DVB) elastomer, to form an interpenetrated network structure with porous morphology. In two practical tests, i-Petrogel with a specific composition (LLDPE/D-DVB:1/1 weight ratio) shows selective absorption of Alaska North Slope crude oil on open water surface with fast kinetics and high absorption capacity of more than 40 times that of the polymer weight. In fact, i-Petrogel effectively stops the crude oil weathering process (ev...

The sensitivity of a deep-sea fish species (Anoplopoma fimbria) to oil-associated aromatic compounds, dispersant, and Alaskan North Slope crude oil.

A predominant concern following oil spills is toxicity to aquatic organisms. However, few data are available on effects in deep-sea cold water fishes. The present study had 3 major objectives. The first was to investigate the relative sensitivity of the deep-sea species Anoplopoma fimbria (sablefish) to acute effects of 3 aromatic compounds (toluene, 2-methylnaphthalene, and phenanthrene), dispersant alone, and chemically enhanced water accommodated fractions (CEWAFs) of Alaskan North Slope crude oil. The second was to determine the critical target lipid body burden (CTLBB) for sablefish by fitting aromatic hydrocarbon toxicity data to the target lipid model (TLM), which then allowed expression of CEWAF exposures in terms of dissolved oil toxic units. The final aim was to apply a passive sampling method that targets bioavailable, dissolved hydrocarbons as an alternative analytical technique for improved CEWAF exposure assessment. The results indicate that sablefish exhibit sensitivity to Corexit 9500 (96-h median lethal concentration [LC50] = 72.2 mg/L) within the range reported for other fish species. However, the acute CTLBB of 39.4 ± 2.1 μmol/goctanol lies at the lower end of the sensitivity range established for aquatic species. The utility of both toxic units and passive sampling measurements for describing observed toxicity of dispersed oil is discussed. The present study is novel in that a new test species is investigated to address the uncertainty regarding the sensitivity of deep-sea fishes, while also employing modeling and measurements to improve exposure characterization in oil toxicity tests. Environ Toxicol Chem 2018;37:2210-2221. © 2018 SETAC.

Generation of shrimp waste-based dispersant for oil spill response.

In this study, shrimp waste was enzymatically hydrolyzed to generate a green dispersant and the product was tested for crude oil dispersion in seawater. The hydrolysis process was first optimized based on the dispersant effectiveness (DE) of the product. The functional properties of the product were identified including stability, critical micelle concentration, and emulsification activity. Water was confirmed as a good solvent for dispersant generation when compared with three chemical solvents. The effects of salinity, mixing energy, and temperature on the dispersion of the Alaska North Slope (ANS) crude oil were examined. Microtox acute toxicity test was also conducted to evaluate the toxicity of the produced dispersant. In addition, DE of the product on three different types of crude oil, including ANS crude oil, Prudhoe Bay crude oil (PBC), and Arabian Light crude oil (ALC) was compared with that of the Corexit 9500, respectively. The research output could lead to a promising green solution to the oil spill problem and might result in many other environmental applications.

Aerial Application of Herding Agents can Enhance In-Situ Burning in Partial Ice Cover

ABSTRACT In situ burning (ISB) aided by herding agents is a promising tool for oil spill response in Arctic waters. An advantageous aspect of the herder mediated ISB approach is that the application of herders as well as the subsequent ignition of the slick could potentially be carried out from aerial platforms. This could obviate the need for personnel to conduct operations on the surface near the burn, as well as reduce the response time required to mobilize the spill response equipment, especially in challenging Arctic conditions. In the last decade, several laboratory and field-scale tests have been conducted to prove the efficacy of herder-assisted ISB operations, sometimes achieving burn efficiencies greater than 90 %. However, there have been no field tests of aerial herder application followed by ignition. This paper presents results from a series of field experiments performed in a custom-built test basin 50 km northeast of Fairbanks, Alaska, in April 2015. A helicopter was employed to first apply herding agents (Siltech OP-40 or ThickSlick 6535) to Alaska North Slope crude oil slicks in simulated drift ice conditions, and then ignite the herded slicks using a Heli-torch. Two of five test burns yielded measurable outcomes, resulting in 70% - 85% removal of the test oil as it was drifting freely. Three of five test burns did not yield reliably measurable results, as wind action at the site prevented an accurate measurement of free-drifting burn efficiency. An unmanned aircraft, carrying prototypical payloads for herder spraying and in situ burn ignition was also tested. This is the first time successful aerial application of herders for ISB in the Arctic or elsewhere has been accomplished, and furthers the development of better tools for oil spill response in Arctic waters and beyond.

Influence of ullage to cavity size ratio on in-situ burning of oil spills in ice-infested water

This study analyzes the results of meso-scale experiments related to in-situ burning of oil spills in ice leads or in close pack ice, which are the two main spill scenarios commonly found in the arctic with the presence of ullage. Alaska North Slope (ANS) crude oil with slick thickness of 0.015m was burned in ice cavities of sizes 1–1.5m with ullage or freeboard of 0.1–0.2m. Heat fluxes on oil surface and ice wall, in-depth temperature profiles in gas phase, oil-layer and water-sublayer, and average burning rate were experimentally measured to analyze the influence of ullage and cavity size on burning. Significant improvement in the burning dynamics was observed with an increase in ullage to cavity size ratio (h/D). This is mainly due to a recirculation zone developed in the cavity causing partial premixing of oil-vapor and entrained air, which promotes a faster burning rate. The implications of experimental findings towards in-situ burning operation for oil spills in ice leads and close pack ice are discussed. Both freshwater and saltwater ices were used and differences are examined.

Class Type Separation of the Polar and Apolar Components of Petroleum.

Identification of the heteroatom (nitrogen, sulfur, and oxygen)-containing compounds of petroleum is of key importance when considering industrial and environmental issues associated with crude oil production. The more commonly performed methods of crude oil fractionation are often insufficient in the extent to which they separate oils, not allowing defined "molecular" fractions to be obtained. Methods capable of performing a class type separation are uncommon and are often extensive and resource and time intensive. Here we report a method for the separation of crude oils into discrete compound classes. The method utilizes both ion exchange and normal phase chromatography to generate fractions of saturated hydrocarbons, aromatic hydrocarbons, basic compounds, naphthenic acids, and other oxygen-containing species, carbazoles, sulfones, and thiophenes from small crude oil samples (∼0.5 g). Assessment of method selectivity with a suite of model compounds has shown the fractions to be well-defined, with classes of model compounds isolated within discrete fractions. Application of the method to five crude oils of varying API gravity (12.1-38.3°) demonstrates a potential for wide-ranging use. Sample recoveries were high (77-98%) with simple evaporative losses correlating closely with total sample loss. Repeatability was also high, demonstrated by triplicate analyses of model compound mixtures, oils spiked with model compounds and oils alone. Separation selectivity was further demonstrated by application of the scheme to the Alaska North Slope (ANS) crude oil and analysis of fractions by comprehensive two-dimensional gas-chromatography mass-spectrometry (GC × GC/MS) and/or liquid-chromatography high-resolution accurate-mass mass-spectrometry methods (LC-HRAM-MS). Isolation of discrete fractions then allowed excellent separation (by LC and GC methods) of carbazole, dibenzothiophene, fluorenones, xanthones, and quinoline fractions. Individual parent and C1-5 alkyl homologues were easily separated (GC × GC/MS), allowing high-quality mass spectra (EI) to be obtained for the individual compounds in many cases. Analysis of fractions by GC × GC/MS also allowed a series of thioxanones to be identified.

Scale-up considerations for surface collecting agent assisted in-situ burn crude oil spill response experiments in the Arctic: Laboratory to field-scale investigations

In the event of a marine oil spill in the Arctic, government agencies, industry, and the public have a stake in the successful implementation of oil spill response. Because large spills are rare events, oil spill response techniques are often evaluated with laboratory and meso-scale experiments. The experiments must yield scalable information sufficient to understand the operability and effectiveness of a response technique under actual field conditions. Since in-situ burning augmented with surface collecting agents (“herders”) is one of the few viable response options in ice infested waters, a series of oil spill response experiments were conducted in Fairbanks, Alaska, in 2014 and 2015 to evaluate the use of herders to assist in-situ burning and the role of experimental scale. This study compares burn efficiency and herder application for three experimental designs for in-situ burning of Alaska North Slope crude oil in cold, fresh waters with ∼10% ice cover. The experiments were conducted in three project-specific constructed venues with varying scales (surface areas of approximately 0.09 square meters, 9 square meters and 8100 square meters). The results from the herder assisted in-situ burn experiments performed at these three different scales showed good experimental scale correlation and no negative impact due to the presence of ice cover on burn efficiency. Experimental conclusions are predominantly associated with application of the herder material and usability for a given experiment scale to make response decisions.