The Arctic Ocean is a net sink for anthropogenic lead deposited into the Atlantic Ocean
Bibliographic record
Abstract
Abstract Humans emitted millions of tons of the toxic element lead (Pb) into the atmosphere. The North Atlantic Ocean has been strongly affected by atmospheric Pb deposition, however the role of ocean currents in dispersing the Atlantic dissolved Pb (dPb) burden remains unclear. Here, we show that the Arctic Ocean received a dPb flux of 611 ± 74 Mg·a -1 from the North Atlantic Ocean in 2015/2016, making the Arctic Ocean a previously unrecognized net sink of Atlantic dPb (378 ± 85 Mg·a -1 ). This input is comparable to Arctic riverine dPb discharge (344 ± 222 Mg·a -1 ). Lead isotope measurements trace the origin of dPb in the Arctic Ocean back to anthropogenic emissions from North America and Eurasia. Elevated dPb concentrations in the North Atlantic Ocean prior to the global-phase out of leaded gasoline (1986-2021) suggests ~5-fold higher fluxes from the North Atlantic in the late 1980s relative to 2015/2016, explaining the widespread contamination of Arctic abyssal sediments with Pb.
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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 | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.002 | 0.001 |
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".