Fate, behaviour and response to oil drifting into scattered ice and ice edge in the marginal ice zone (MIZ)

Future petroleum activities in Arctic waters are expected to take place in areas free of ice most of the year, but with the possibility for conflict between a possible oil release and drifting sea ice in periods during the winter season. Oil drifting towards the ice edge or into a marginal ice zone will be more weathered when meeting the ice. The project has contributed to advancing the knowledge of the fate and behaviour of oil released in open water and drifting into the scattered ice or meeting an ice barrier. Moreover, the project acquires new documentation of the feasibility of operative response options for weathered oils that meets an ice barrier or are drifting into scattered ice. Knowledge derived from this project is considered equally important to the oil industry as to organizations and authorities responsible for oil spill preparedness, and oil spill response operations including shipping incidents. The project was carried out in cooperation with industry partners, R&D institutions Canada and oil spill response organizations in Norway and Canada. A literature review for recent R&D projects focusing on weathered oils interaction with sea ice and oil spill in the Arctic justified the need for increased understanding of the fate and behaviour of weathered oil drifting into sea ice. Comprehensive laboratory experiments have been performed that include oil-ice interaction studies in a novel wave and current flume, testing of response options in bench-scale laboratory, meso-scale flume testing with focus on use of dispersants and supplement of artificial energy and in-situ burning (ISB) of weathered oil in different ice conditions. Experiments in a novel wave and current flume have contributed to increased documentation of physical processes taking place when different oil types with different weathering degrees hits an ice barrier and interact with and are distributed in different ice conditions. Two ice regimes (solid and frazil ice) were simulated to study film thickness of weathered oil against an ice barrier, oil to ice adhesion, oil transport under ice and oil against frazil ice. It was demonstrated that weathered oil can migrate on the top of frazil ice, and vertically in frazil ice. Furthermore, oil thickness against an ice barrier was studied to develop an approach for predicting thickness in model tool (OSCAR). Findings from oil-ice interaction have been presented at conference and in a manuscript for peer-review. Adhesion testing of weathered oils to ice and a polyethylene skimmer material has been published in Marine Pollution Bulletin. Testing of dispersibility and ignitibility of weathered oils have shown a potential for use of dispersants and in-situ burning (ISB), but the efficiency is highly dependent on the oil types and their weathering properties. Adding emulsion breaker to increase the time window for ignitability has showed a potential for some of the weathered oils. Use of artificial energy by high-capacity water flushing showed to enhance the dispersion effectiveness after dispersant application in calm sea conditions and demonstrated a promising concept. Results are presented at conferences and in conference peer-review manuscript. Biodegradation and microbial degradation of chemically dispersed oil in frazil ice and oil frozen into solid ice were studied as a part of a PhD-study. This included identification of microbes involved in biodegradation of oil components. Long-term experiments in frazil ice indicate that single components of the weathered oil can be biodegraded in cold temperatures. However, no significant loss of total extractable hydrocarbons was observed, neither in the oil samples containing frazil ice, nor in oil samples containing only sea water. The microbial community responds to the presence of oil, and typical oil degraders were selected over time. The microbial community was different in samples with frazil ice, and samples with sea water alone. Results have been presented at conference and will be published as a part of the PhD-thesis. The trajectory model (OSCAR) has been improved focussing on a set of case studies using different versions of the model during the project period to demonstrate new developments of oil-ice interaction from this and other projects. Results are presented at conference and in manuscripts on biodegradation rates and thickness of oil in the presence of an ice barrier (Nordam el al. 2020). An Arctic Oil Spill Response (AOSR) module was developed and delivered as a research version from this project to provide recommendations for choice of response technology for oils released in open water and drifting into ice covered waters. Scenario-based recommendations for evaluation of relevant response options with respect to acute oil spills in Arctic areas have been developed given in a SINTEF scientific report.

1) Prosjektet har gitt økt dokumentasjon av viktige fysiske prosesser når ulike forvitrete oljer møter is, både fast-is og sørpe-is. Dette har bidratt for videreutvikling av operative modellverktøy for simulering av scenarioer med ulike oljer som drifter inn mot isfylte farvann. 2) Effektivitetsstudier med dispergeringsmiddel og brenning av oljer ved ulike isforhold har gitt viktig input til utvikling av operative støtteverktøy i valg av tiltak for både beredskapsplanlegging og strategier under reelle oljevernaksjoner i is. 3) PhD-studiet har gitt viktig dokumentasjon på biologisk nedbrytning av dispergert olje i kontakt med is, som igjen vil være viktig kunnskap ved en vurdering av responstiltak (NEBA). 4) Prosjektet har gitt et viktig grunnlag for tilrettelegging av fremtidig feltforsøk med olje og is.5) Det er utviklet et internasjonalt samarbeid med F&U partnere i Canada med grunnlag for fremtidige prosjekter innenfor tiltak og effekter ved akutt oljeforurensning i isfylte farvann.

Today we don't have sufficient knowledge and understanding about the fate and behaviour of weathered oil getting in contact with the ice edge or scattered ice conditions. Different physical processes may take place: The oil may be contained on the sea surface at the ice edge, or be up-concentrated and pushed under the ice in high-energetic wave conditions. Depending on the oil type and the degree of weathering some oils may be adsorbed to the ice while others can be easily washed off the ice. The interaction of weathered oils with different ice types (e.g. frazil ice, slush ice, ice floes) is a topic that will be addressed in this project. This project we will generate knowledge about how different oil types at different weathering degrees, drifting from an open water release, will interact with the the ice edge or scattered ice in the marginal ice zone. Their fate and behaviour will be crucial for establishing a robust oil spill response technology. Combined with the biodegradation potential for such weathered oils this will be very important input to models used for simulating environmental risk and response effectiveness for such scenarios. Findings from this project along with results from previous and ongoing projects will be used for improvement of such operative model tools. The project will be performed in close cooperation with the oil industry and response organisations in Norway and Canada. Results from the project will be important contribution in developing reliable future oil spill contingency plans for exploration and production fields in the Barents Sea, and contribute with new knowledge as a foundation for robust oil spill response strategies.