An Historical Record of Toxaphene and Its Congeners in a Remote Lake in Western Europe
Bibliographic record
Abstract
Historical trends in the concentrations of toxaphene, its component homologue groups, and individual chlorobornane congeners were determined in a dated sediment core from a mountain lake, Lochnagar, in Scotland, U.K., representing the first such profiles outside of North America. The profile of total toxaphene showed a bimodal distribution with maxima in the mid-1970s and early 1990s unlike the unimodal PCB profile (maximum 1973) in the same core. The earlier toxaphene peak shows agreement with the U.S. source curve and therefore may correspond to modeled global patterns while the later peak may be dueto long-rangetransportfrom eastern and southern Europe or from still lower latitudes. Sediment toxaphene concentrations (14 ng/g dry wt (dw) at surface; 40 ng/g dw at maximum) and accumulation rates (surface 0.42 ng cm(-2) yr(-1); maximum 1.6 ng cm(-2) yr(-1)) were considerably higher than levels in untreated sites in the Great Lakes region and the Canadian Arctic and are equivalent to those reported for the Great Lakes themselves where there have been additional riverine inputs. Two toxaphene congeners, B6-923 and B7-1001, accounted for most of the hexa- and heptachlorobornanes, respectively. B6-923 and B7-1001 abundance ratios (relative to the sum of 12 chlorobornane congeners) had doubling times of 17 +/- 3 and 12 +/- 3 yr, respectively. Given the remoteness of the site from areas of toxaphene production and usage, the high sediment levels raise concerns over toxaphene levels in areas of Europe closer to sources, especially where sites are fished for human consumption. Further European data are needed for comparison.
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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 | 0.002 |
| Science and technology studies | 0.000 | 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".