15. The Comparative Toxicity of two Canadian Diluted Bitumens to Developing Yellow Perch (Perca flavescens)
Bibliographic record
Abstract
Increasing demand for diluted bitumen (dilbit) has led to the development of the Alberta oil sands industry and the expansion of current and future transcontinental pipelines. However, the growth of oil transportation has led to public concern about the effects of potential dilbit spills to aquatic ecosystems. Although the toxic effects of crude oils through exposure to polycyclic aromatic hydrocarbons (PAH) are well characterized, little is known about the toxic effects of dilbit because of the variable proportions of diluent added to bitumen. Here we assessed the toxicity of the two most transported dilbits in Canada, Access Western Blend (AWB) and Cold Lake Blend (CLB) to developing yellow perch (Perca flavescens), a species distributed throughout North America. Embryos were exposed to dilbit until hatch, or up to 16 days, using a static daily renewal treatment regime of water accommodated fractions (WAF) and chemically-enhanced water accommodated fractions (CEWAF) of dilbit at total PAH (TPAH) concentration ranges of 0.02 to 10.7 μg/L and 0.21 to 20.4 μg/L TPAH, respectively. Results show that with increased TPAH concentration, the frequency of hatched embryos with developmental malformations increased proportionally. Expression of genes associated with phase I and II detoxification, cellular stress, and xenobiotic metabolism were altered in higher TPAH concentrations. This is the first study assessing the toxicity of both AWB and CLB dilbits on wild-sourced fish. With recent approvals of pipelines in North America, these biomarkers will assist risk assessments and monitoring of Canadian ecosystems should a pipeline spill occur.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".