Occurrence and Toxicity of Photomodified Polycyclic Aromatic Hydrocarbon Mixtures Present in Contaminated Sediments
Bibliographic record
Abstract
Exposure of PAHs to solar radiation results in the generation of oxygenated products. Many of these oxyPAHs are more toxic and/or carcinogenic than the parent compounds. Environmental photomodification of PAHs could result in formation of toxic compounds not anticipated by regulatory agencies. We have confirmed the presence of oxyPAHs at toxic levels in sediment samples taken from a known contaminated site. Contaminated sediment samples were taken from Hamilton Harbour (Hamilton, Ontario). A reference site from the harbour, known to be free of contaminants was also analyzed. High performance liquid chromatography (HPLC) was used to fractionate, and analyze individual compounds present. Fractions were tested for toxicity using both short-term, and long-term assays on the bacterium Vibrio fischeri.OxyPAHs were found in sediments at concentrations comparable to intact PAHs. Testing confirmed toxicity in fractions containing oxyPAHs on the order of intact PAH-containing fractions. It is concluded that environmental photomodification of PAHs contributes to the presence of toxic compounds that are not properly addressed by current regulations in the U.S. and Canada.
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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 | 0.001 |
| 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) | 0.003 | 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".