New Radiocarbon Constraints on the Global Cycling of Solid‐Phase Extractable Dissolved Organic Carbon
Bibliographic record
Abstract
Abstract Radiocarbon (∆14C) measurements suggest the deep ocean stores marine dissolved organic carbon (DOC) on millennial timescales. The mechanisms that mediate this residence time remain unconstrained. Solid‐phase extraction (SPE) has emerged as a widely used technique to isolate DOC for subsequent analyses. We present SPE‐DOC concentrations and ∆14C values for three GO‐SHIP Repeat Hydrography transects, spanning the Pacific, Southern and Indian Oceans. Comparisons of SPE‐DOC with total DOC ∆14C values are used with an isotopic mass‐balance to estimate the size of the refractory DOC (RDOC) reservoir and changes in RDOC relative abundance in the global ocean. Estimated RDOC abundance is similar across the deep Pacific and Indian Oceans (average = 93 ± 5%, 35 ± 6 μM), whereas RDOC in the surface ocean varies as a function of total DOC concentration. Our results fill in spatial SPE‐DOC ∆14C sampling gaps for the global ocean, and our mass‐balance RDOC estimates are consistent with previous observations.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".