Coupled nitrogen and oxygen isotope measurements of nitrate along the eastern North Pacific margin
Bibliographic record
Abstract
Water column depth profiles along the North Pacific margin from Point Conception to the tip of Baja California indicate elevation of nitrate (NO 3 − ) 15 N/ 14 N and 18 O/ 16 O associated with denitrification in the oxygen‐deficient thermocline waters of the eastern tropical North Pacific. The increase in δ 18 O is up to 3‰ greater than in δ 15 N, whereas our experiments with denitrifier cultures in seawater medium indicate a 1:1 increase in NO 3 − δ 18 O and δ 15 N during NO 3 − consumption. Moreover, the maximum in NO 3 − δ 18 O is somewhat shallower than the maximum in NO 3 − δ 15 N. These two observations can be summarized as an “anomaly” from the 1:1 δ 18 O‐to‐δ 15 N relationship expected from culture results. Comparison among stations and with other data indicates that this anomaly is generated locally. The anomaly has two plausible interpretations: (1) the addition of low‐δ 15 N NO 3 − to the shallow thermocline by the remineralization of newly fixed nitrogen, or (2) active cycling between NO 3 − and NO 2 − (coupled NO 3 − reduction and NO 2 − oxidation) in the suboxic zone.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".