Nitrogen isotopes in bulk marine sediment: linking seafloor observations with subseafloor records
Bibliographic record
Abstract
Abstract. A global database of nitrogen isotope data from marine sediments is presented, including both seafloor and sub-seafloor sediment samples. The data synthesis reveals regionally and globally consistent patterns and trends, with good agreement between neighbouring seafloor sites. The spatial coverage of seafloor δ15N data is heterogenous, with excellent coverage in the eastern tropical Pacific, South China Sea and Arabian Sea, while large regions of the globe remain unsampled. The sub-seafloor δ15N records are mostly from the late Pleistocene, with >90 coeval records during the last ~10 kiloyears (kyr), before which the number of records at any time decreases, with <10 coeval records at any time prior to 300 kyr. There is a good correlation between seafloor and shallow-subseafloor δ15N measurements within a 100 km radius, which suggest a reliable translation of sediments into the buried sediment record. We suggest that regional discrepancies between seafloor and late Holocene subseafloor δ15N indicate nitrogen cycle changes during the late Holocene period, rather than systematic diagenetic changes.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.000 | 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) | 0.000 | 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".