The toxic effects of oil sands contaminants on fish
Bibliographic record
Abstract
Extracting bitumen from the Canadian oil sands is a water-intensive process that produces large volumes of oil sands process-affected water (OSPW). The recycling of OSPW for bitumen extraction causes it to become highly contaminated with salts, metals, residual bitumen, and dissolved organic compounds called naphthenic acid fraction components (NAFCs). Currently, large volumes of OSPW are being stored in temporary settling basins called tailings ponds. As OSPW is known to be toxic to a variety of organisms, there is increasing concern about accidental breaching and leaking of OSPW from tailings ponds into the environment. To mitigate these risks, there are plans for controlled releases of treated OSPW into surrounding environments. More information on the sub-lethal effects of OSPW, and particularly NAFCs derived from OSPW, is needed to inform regulations that will protect wildlife and human populations living downstream of the oil sands region. Our studies evaluated whether exposure to NAFCs extracted from OSPW has lethal and sub-lethal effects on fish. Our first study exposed fathead minnow (Pimephales promelas) embryos to environmentally relevant concentrations of NAFCs (2 - 54 mg/L) for 7 days, then raised surviving larvae in outdoor mesocosms of clean lake water for 1 month. We found that embryonic exposure to NAFCs resulted in decreased embryo survival and impaired development, with persistent adverse effects on larval fish survival and behaviour after one month of rearing in lake water. Our second study exposed juvenile yellow perch (Perca flavescens) to environmentally relevant concentrations of NAFCs for 7 days and monitored the fish for changes in behaviour before and after NAFC addition. We found that juvenile exposure to NAFCs (15 mg/L) impaired fish survival, fish equilibrium while swimming, and antipredator behaviour in fish. Our findings show that NAFCs have both lethal and sub-lethal effects on fish development and behaviour that could affect their survival and performance following exposure. These findings are pertinent for developing evidence-informed decisions regarding planned OSPW releases in the Canadian oil sands region.
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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) | 0.002 | 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".