Establishing baseline levels of extractable trace metals in marine surface sediment of the Canadian Arctic
Bibliographic record
Abstract
A comprehensive spatial assessment of extractable trace metal, including rare earth element (REE), distribution in the Canadian Arctic was conducted based on terrestrial and marine surface sediment samples to evaluate the current state of metal contamination. Major and trace element concentrations were determined by HNO 3 -HCl partial digestion and triple quadrupole inductively coupled plasma mass spectrometer measurements. Results revealed significant regional variations in trace metal concentrations (e.g., Cr = 5–96 μg/g; Zn = 9–139 μg/g; ΣREE = 21–358 μg/g), with a clear West-East gradient. The highest non-REE metal concentrations are observed in Beaufort Sea and Amundsen Gulf, highlighting the influence of the Mackenzie River. Conversely, the REEs are concentrated near the coasts underlain by Canadian Shield rocks in the south-central and eastern Canadian Arctic. Normalized REE distribution patterns show an enrichment in light REEs compared to heavy REEs. The pollution indices indicate generally low enrichment or contamination, although few samples exhibit moderate arsenic enrichment/contamination in the Beaufort Shelf and Jones Sound. Based on the Canadian sediment quality guidelines, most samples had metal concentrations below the Probable Effects Level. However, concentrations exceeding this threshold were measured for arsenic (> 41.6 μg/g) and nickel (> 42.8 μg/g) in the Amundsen and Coronation gulfs, Jones Sound and Baffin Bay. Despite localized contamination, the trace metal distribution exhibit natural concentrations influenced by the regional geology and sedimentary processes. This geochemical baseline offers new insights from previously uncharacterized areas, improving our understanding of the sources and fate of trace metals and the accuracy of environmental monitoring of the Canadian Arctic. • Highest metal concentrations were measured in Mackenzie Shelf and Amundsen Gulf. • Highest REE concentrations were measured along the Baffin Island coast. • Pollution indices and sediment quality criteria indicate no major ecological risks. • As exceeded the PEL and presented moderate enrichment in Jones Sound and near Banks Island.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.002 | 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".