Identification of dominant natural sources of polycyclic aromatic hydrocarbons in river sediments in Alberta
Bibliographic record
Abstract
Sediment collected from the rivers of southern Alberta, Canada, presents patterns of polycyclic aromatic hydrocarbons (PAHs) that demonstrate a varied origin within the Rocky Mountains. An influx of PAHs from sub-bituminous coal sources from erosional processes as the river exit the mountains dominates the pattern of PAHs in the river sediment across the prairies to the Alberta-Saskatchewan border (a distance of 750 km for the Red Deer River and 925 km for the Bow River) continues much further downstream. The concentrations of PAHs are similar to the well-studied Athabasca River in the Alberta Oil Sands Region. Although these results relate to rivers flowing east from the Rocky Mountains in Canada, it is likely that coal-sourced PAHs will contribute to any river where erosion of coal formations is possible within the watershed. A distinctive natural pattern of strongly pyrogenic PAHs from nearby thermal hot springs was also discovered near Banff. Natural pyrogenic PAH sources, aside from wildfires, are uncommon and generally related to hydrothermal vents and igneous intrusions into source rocks. This is the first time the authors are aware of sediment from a thermal spring presenting such PAH patterns.
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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 | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 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".