Oil Sands Facilities Are an Emission Source of Naphthenic Acid Fractional Compounds to the Atmosphere
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide The oil sands (OS) region in Canada hosts one of the world’s largest unconventional crude oil deposits in the form of bitumen, which, when extracted, generates substantial tailings/wastewater that are stored in on-site ponds. Naphthenic acid fractional compounds (NAFCs), a complex mixture of alkyl-substituted acyclic and cycloaliphatic organic acids, are natural bitumen components known for their ecological toxicity and are concentrated during the extraction process into tailings ponds, where they are assumed to remain confined to the aqueous phase. Here, we quantify the emissions of up to 275 NAFCs to the atmosphere from a tailings pond and from facility-wide operations at major OS facilities. The results indicate that, despite the absence of NAFC air emissions in inventories, large quantities are emitted to the atmosphere, likely originating from surface photochemical and/or biodegradation processes. Emission rates across entire operations ranged from 3509 to 7286 kg h –1, translating to annual emissions of 1163–2660 tonnes from both primary and secondary sources. The findings imply that NAFC air emissions may serve as a key pathway for these chemicals to enter the environment, potentially impacting downwind ecosystems.
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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 | 0.001 | 0.001 |
| 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) | 0.004 | 0.001 |
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".