Integrating physical, chemical and biological data to understand fate, behaviour and effects of diluted bitumen in coastal waters
Bibliographic record
Abstract
ABSTRACT: 1141488 Production of bitumen from oil sands is predicted to rise over the next decade. Some of this increased production will be transported to coastal areas for export. While some product will be transported via rail, the majority is likely to be transported through pipelines as diluted bitumen. This unconventional oil product is a mixture of the highly viscous bitumen with differing amounts of diluent, which can include condensates, synthetic crudes or conventional crudes. As a mixture of products, the behaviour of diluted bitumen may differ from conventional heavy crude oils following a spill. This is of concern in Canada as the main transportation route for exporting diluted bitumen will go through the Salish Sea, home to endangered southern resident killer whales, economically important commercial and traditional fisheries including Pacific salmon, and millions of people. Knowing how diluted bitumen products will behave and their potential impacts if a spill occurs in these coastal waters is important in developing an effective response plan. The Centre for Offshore Oil, Gas and Energy Research (COOGER) within Fisheries and Oceans Canada (DFO) has been carrying out research to characterize and predict the fate and behaviour of diluted bitumen products in marine environments over the last seven years. Using a combination of small-scale microcosms, medium-scale mesocosms, large-scale weathering and wave tank studies as well as field experiments, we have collected a broad range of data providing insights into how diluted bitumen might behave following a spill. Our research suggests that diluted bitumen will weather rapidly, with density and viscosity increasing significantly over the first 48 h. Low concentrations of hydrocarbons are typically detected in the water column, even in the presence of high energy breaking waves. The amount of weathering and water column hydrocarbons vary with season, but overall the microbial community shows a small response to the presence of diluted bitumen. Conventional spill response technologies may be used within the first 48 h of a spill, but extensive weathering will further limit their effectiveness. While the studies provide a more complete understanding of the fate and behaviour of diluted bitumen in coastal waters, there are important questions yet to be answered, some of which are presented here.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".