Trend Analysis Reveals a Recent Reduction in Mirex Concentrations in Coho (<i>Oncorhynchus kisutch</i>) and Chinook (<i>O. tshawytscha</i>) Salmon from Lake Ontario
Bibliographic record
Abstract
Lake Ontario, bordering both Canada and the United States, is the only Great Lake with persistent, significant levels of mirex in its biota. Some models suggested that it would take hundreds of years before mirex disappeared from the ecosystem. From 1977 to 1996 the mirex concentrations in coho and chinook salmon greater than 2 kg in weight exceeded the 0.1 mg/kg Food and Drug Administration (FDA) action level for mirex. To determine temporal trends in salmonine mirex levels, slopes and elevations of the regression lines of mirex concentration versus fish weight were compared for each of the six sampling years (1977, 1982, 1986, 1992, 1996, and 1999) by ANCOVA with weight as a covariate. Within 24 years of mirex being banned, mirex least-squares mean concentrations in salmon fillets had decreased significantly. ANCOVA revealed that the slope of the 1999 regression line was significantly flatter (P < or = 0.014) than the slopes of all other regression lines except 1996 (P = 0.966). A Tukey test revealed that the elevation of the 1999 regression line was also significantly lower than all other years (P < 0.001). Based on our results, mirex concentrations in the fillets of most salmon under the size of 12 kg are now below the 0.1 mg/kg United States FDA action level for human consumption. Models suggest that mirex reductions in biota are most likely due to the settling of mirex-contaminated organisms to the sediments and the loss of mirex from the lake through the St Lawrence River. A third mechanism is suggested as the cause of the higher rate of reduction observed in the mid to late 1990s--the control and removal of contaminated groundwater at the former Hooker Chemical site on the Niagara River, the major source of mirex in the watershed of Lake Ontario.
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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 | 0.001 | 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) | 0.001 | 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".