Effects of crude oil and field-generated burned oil residue on Northern shrimp (Pandalus borealis) larvae

In Situ Burning for Oil Spill Response in the Arctic: Recovery and Quantification of Chemical Herding Agent OP-40 from Burned Oil Residues

In situ burning (ISB) aided by OP-40 is one of the best suited and effective oil spill response techniques for Arctic conditions. However, the fate of OP-40 in the environment after an ISB event is not fully understood, especially the amount of OP-40 remaining within the burned oil residues. Previous studies reported partial accumulation of OP-40 in water, and no OP-40 was measured in the air emissions following the burn. Accumulation of OP-40 in burned oil residues is not appropriately quantified as it is challenging to process and analyze burned oil samples in the laboratory, and there exists no standard method in the literature to measure and quantify OP-40 in burned residues. In this work, we report on the development of an analytical method for the quantification of OP-40 in burned oil residues using column chromatography, followed by gas chromatography-mass spectrometry analysis which was successfully employed to measure more than 90% of the applied OP-40 in the burned residues for controlled bench-scale burns. Additionally, the robustness of the developed method was further tested by measuring OP-40 in burn residues from ISBs conducted at different oil-water emulsion ratios (60-100% oil) and water temperatures (4-35 °C), wherein known amounts of OP-40 were added to the residues. Results indicate that the method is equally effective for different oil-water emulsions, but the OP-40 recoveries (89.2-115.6%) are significantly higher at warmer temperatures than the OP-40 recoveries (87.0-103.3%) at colder temperatures. Overall, the method developed in this work could assist in the understanding of the fate of OP-40 in a potentially important environmental matrix of burned oil residues that are left behind sometimes long (weeks to years) after an ISB event.

Offshore field experiments with in-situ burning of oil: Emissions and burn efficiency

In situ burning (ISB) is an oil spill response technique including ignition and burning to remove oil on the water surface. The technique rapidly and effectively removes large portions of the oil. However, the combustion process causes a large smoke plume and leaves a viscous residue in the water. During six large-scale experimental burns in the North Sea in 2018 and 2019, the smoke plume, released oil and contained residues were analysed. The objectives were to document the content of particles and gases in the smoke plume, properties of both the released oils and residues, and the effectiveness of the burns. Oseberg crude oil, Ultra Low Sulphur Fuel Oil (ULSFO), Intermediate Fuel Oil (IFO180) and Marine Gas Oil (MGO) were released into a fire-boom and ignited. Particles and gases in the smoke plume were monitored using drones with several sensors. Soot particle monitoring indicated that more than 90% of the particles produced during the burns were <1 μm. Soot fallout was mainly limited to visible smoke, and the particle concentration was highest directly under the smoke plume and declined with distance from the burn. Gas monitoring in the smoke indicated low concentrations of SO₂ and NO_X (<2 ppm), and the concentrations of CO₂ and CO were within air quality standards. Black Carbon produced relative to the amount of oil burned was 10-18%. The burn efficiency varied and were estimated to 80-91% for Oseberg, >90% for MGO, and <60% for both ULSFO and IFO180. The present paper addresses the results of the smoke plume monitoring, properties of the ISB residues and the burn efficiency.

Effects of chronic exposure to the water-soluble fraction of crude oil and in situ burn residue of oil on egg-bearing Northern shrimp (Pandalus borealis)

Oil spill clean-up measures using in situ burning can potentially result in seafloor contamination affecting benthic organisms. To mimic realistic exposure and measure effects, ovigerous Northern shrimp were continuously exposed for two weeks to the water-soluble fraction of oil coated on gravel followed by two weeks in clean seawater. North Sea crude oil (NSC) and field generated in situ burn residue (ISBR) of NSC were used (Low: 3 g/kg gravel, Medium: 6 g/kg gravel and High: 12 g/kg gravel). The concentrations of polyaromatic hydrocarbons (PAHs) in the water resulting from NSC were higher compared to ISBR. No mortality was observed in any treatment and overall moderate sublethal effects were found, mostly after exposure to NSC. Feeding was temporarily reduced at higher concentrations of NSC. PAH levels in hepatopancreas tissue were significantly elevated following exposure and still significantly higher at the end of the experiment in NSCHigh and ISBRHigh compared to control. Mild inflammatory response reactions and tissue ultrastructural alterations in gill tissue were observed in both treatments. Signs of necrosis occurred in ISBRHigh. No change in shrimp locomotory activity was noted from NSC exposure. However, ISBR exposure increased activity temporarily. Larvae exposed as pleopod-attached embryos showed significant delay in development from stage I to stage II after exposure to NSCHigh. Based on this study, oil-contaminated seafloor resulting from in situ burning clean-up actions does not appear to cause serious effects on bottom-living shrimp.