Particulate Export of PAHs Firstly Traced by <sup>210</sup>Po/<sup>210</sup>Pb Disequilibrium: Implication on the “Shelf Sink Effect” in the Arctic Ocean
Bibliographic record
Abstract
Abstract In the changing Arctic Ocean, organic pollutants' transport and biogeochemical processes are strongly influenced by their particulate export on the broad continental shelf. To better evaluate the vertical particulate export of polycyclic aromatic hydrocarbons (PAHs), seawater samples were collected from the Bering Sea, Chukchi Sea, and Canada Basin with the first application of 210Po/210Pb disequilibrium during the summer of 2012. Dissolved PAHs (1.1–19 ng L−1, mean 5.2 ± 3.6 ng L−1) showed spatial distinctions, with high values on the Bering Shelf and low values in the Chukchi Sea, while particulate PAHs (1.0–12 ng L−1, mean 5.0 ± 3.5 ng L−1) showed high levels in the nutrient‐rich Bering Shelf Water layer. According to the 210Po/210Pb deficit on the Bering Shelf, the export fluxes of particulate PAHs ranged from 1,201 ± 276 to 3,650 ± 1,570 ng m−2 d−1, and their residence time ranged from 55 ± 23 to 133 ± 31 days. From the Bering Shelf to the Chukchi Sea, the decreased inventories of dissolved PAHs were positively related to their vertical particulate export fluxes (R2 = 0.62), suggesting the “Shelf Sink Effect” on PAHs.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".