Isotopic evidence for bioaccumulation of aerosol lead in fish and wildlife of western Canada
Bibliographic record
Abstract
Lead (Pb) is a toxic element which is released as a result of anthropogenic activities, and Pb stable isotope ratios provide a means to distinguish sources and transport pathways in receiving environments. In this study, isotopes of bioaccumulated Pb (204Pb, 206Pb, 207Pb, 208Pb) were examined for diverse terrestrial and aquatic biota from three areas in western Canada: (a) otter, marten, gulls, terns, and wood frogs in the Alberta Oil Sands Region (AOSR), (b) fish, plankton, and gulls of Great Slave Lake (Yellowknife, Northwest Territories), and (c) wolverine from the Yukon. Aquatic and terrestrial biota from different habitats and a broad geographic area showed a remarkable similarity in their Pb isotope composition (grand mean ± 1 standard deviation: 206Pb/207Pb = 1.189 ± 0.007, 208Pb/207Pb = 2.435 ± 0.009, n = 116). Comparisons with Pb isotope ratios of local sources and environmental receptors showed that values in biota were most similar to those of atmospheric Pb, either measured in local aerosols influenced by industrial activities in the AOSR or in lichens (an aerosol proxy) near Yellowknife and in the Yukon. Biotic Pb isotope ratios were different from those of local geogenic Pb. Although the Pb isotope measurements could not unambiguously identify the specific anthropogenic sources of atmospheric Pb in biota, initial evidence points to the importance of fossil fuels currently used in transportation and power generation. Further research should characterize bioavailable chemical species of Pb in aerosols and important emission sources in western 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 | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| 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".