Historical Trends in Mercury Sedimentation and Mixing in the Strait of Georgia, Canada
Bibliographic record
Abstract
Seventeen sediment cores collected in the Strait of Georgia reveal a history of mercury contamination that began in the 1860s and include episodic contamination during World War II and in the late 1960s. Surface sediment mercury concentrations ranged from 60 to 420 ng/g dry weight and the current fluxes to sediments are estimated at 5-181 ng cm(-2) a(-1). In one location in Port Moody Arm, a Hg spill seems to have sufficiently poisoned the sediments to eliminate biomixing for about 20 years. Although the surface concentration of Hg is likely to decrease at all stations in coming years, sites in the industrialized Vancouver Harbor and Port Moody Arm will continue to be sufficiently contaminated to endanger benthic organisms. Variations in sedimentation and mixing rates among sites result in surface sediment Hg concentration patterns that do not reflect accurately the distribution of Hg flux. In particular, the concentration of Hg in sediments near the mouth of the Fraser River is low, despite the high Hg load of that river, because of dilution by other particles. A preliminary Hg budget indicates that most of the Hg enters the Strait of Georgia via the Fraser River (2090 kg a(-1)), and that, while burial in Strait of Georgia sediments is a major sink (1800 kg a(-1)), there may be a significant outflow of Hg through Juan de Fuca Strait (approximately 3400 kg a(-1)).
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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 | 0.003 | 0.006 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".