A baseline assessment of the occurrence, characterization, source, and risk impact of petroleum-related hydrocarbons in sediments along the southeast shoreline of Vancouver Island and Southern Gulf Islands in British Columbia, Canada
Bibliographic record
Abstract
Total petroleum hydrocarbons (TPH), n -alkanes, petroleum biomarkers, and polycyclic aromatic hydrocarbons (PAHs) were analyzed in 63 intertidal zone sediments from the southeast shoreline of Vancouver Island and the nearby Southern Gulf Islands, British Columbia (BC), Canada, using gas chromatography coupled with a flame ionization detector and mass spectrometry. All sites had TPH levels much lower than the Canadian Council of Ministers of the Environment thresholds for fine- and coarse-grained soils in agricultural and natural areas. Terrestrial plants were the main source of n -alkanes, though petrogenic n -alkanes were found in 13% of 63 samples, as indicated by the carbon preference index (CPI) and related characteristics. PAHs primarily originated from pyrogenic input, with some locations showing mixed petrogenic and pyrogenic inputs based on analyzing diagnostic ratios, like pyrogenic index and certain isomer ratios. Petroleum contamination was evident at sites with intensive human activities or oil spill history, such as Cowichan Bay, Octopus Point, Medicine Beach, Fulford Harbor, East Portland, Separation Point, Maple Bay, and Aldridge Point, marked by significant levels of petroleum biomarkers, petrogenic n -alkanes, and PAHs. While all PAHs pose minimal risk to benthic organisms, compounds like naphthalene, 2-methyl naphthalene, and certain 3–6 ring PAHs could potentially affect them at certain sites from Cowichan Bay, East Portland, Separation Point, Medicine Beach, and Maple Bay.
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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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".