Isotopic Constraints on Nitrogen Transformation Rates in the Deep Sedimentary Marine Biosphere
Bibliographic record
Abstract
Abstract Little is known about the nature of microbial community activity contributing to the cycling of nitrogen in organic‐poor sediments underlying the expansive oligotrophic ocean gyres. Here we use pore water concentrations and stable N and O isotope measurements of nitrate and nitrite to constrain rates of nitrogen cycling processes over a 34‐m profile from the deep North Atlantic spanning fully oxic to anoxic conditions. Using a 1‐D reaction‐diffusion model to predict the distribution of nitrogen cycling rates, results converge on two distinct scenarios: (1) an exceptionally high degree of coupling between nitrite oxidation and nitrate reduction near the top of the anoxic zone or (2) an unusually large N isotope effect (~60‰) for nitrate reduction that is decoupled from the corresponding O isotope effect, which is possibly explained by enzyme‐level interconversion between nitrite and nitrate.
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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) | 0.000 | 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 | 0.001 |
| 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".