Comparison of Polycyclic Aromatic Compounds in Air Measured by Conventional Passive and Passive Dry Deposition Samplers and Contributions from Petcoke and Oil Sands Ore
Bibliographic record
Abstract
Abstract. Conventional passive air samplers (PAS) and passive dry deposition (PAS-DD) samplers were deployed along a 90 km south-north transect at five sites in the Athabasca oil sands region during October to November 2015. The purpose was to compare and characterize the performance of the two passive sampling methods for targeted compounds across a range of site types. Samples were analyzed for polycyclic aromatic compounds (PACs), nitrated polycyclic aromatic hydrocarbons (NPAHs), and oxygenated PAHs (OPAHs). ΣPAC and ΣNPAH concentrations were highest in PAS and PAS-DD samplers at site AMS5, which is the closest sampling site to surface mining and upgrading facilities. The OPAHs were elevated at site AMS6, which is located in the town of Fort McMurray, approximately 30 km south of the main mining area. The PAS-DD was enriched relative to the PAS in particle associated target chemicals, which is consistent with the relatively more open design of the PAS-DD intended to capture particle- (and gas-phase) deposition. Petroleum coke (petcoke) (i.e. the carbonaceous by-product of bitumen upgrading) and oil sands ore (i.e. the material mined in open pit mines from which bitumen is extracted) were assessed for their potential to be a source of PACs to air in the oil sands region. The ore samples contained ~ 8 times and ~ 40 times higher ΣPACs concentrations (dry weight basis) than delayed and fluid petcoke, respectively. The residue analysis of ore and petcoke samples also revealed that the chemical 4-nitrobiphenyl (4-NBP) can be used to track gas-phase emissions to air. A comparison of chemical residues in ore, petcoke and air samples revealed that the ore is likely a major contributor to volatile PACs present in air and that both ore and petcoke are contributing to the particle-associated PACs in air near open pit mining areas. The contribution of petcoke particles in passive air samples was also confirmed qualitatively using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".