Bibliographic record
Abstract
Abstract. Quantitative estimates of particulate organic carbon (POC) flux and burial in coastal systems are critical for constraining coastal carbon budgets and understanding their role in regional and global carbon cycling. In this study, POC export fluxes were quantified in the Bedford Basin, a coastal inlet in the Northwest Atlantic, based on measurements of 234Th/238U disequilibria and the POC:234Th ratio on small (1–51 µm) and large (> 51 µm) particles. These water column export fluxes were compared to sediment accumulation fluxes of 234Th and POC to refine the carbon budget in the Bedford Basin. The coupled water column-surficial sediment sampling approach, which is relatively new, was applied quasi-seasonally throughout 2021–2024, including for the first time in boreal winter. Total 234Th activities reveal persistent deficits with respect to 238U throughout the water column, likely due to extensive particle scavenging, which is also indicated by high 234Th activities on particles. Here, we find that the removal of 234Th in the water column is typically balanced, within uncertainties, by the inventory of excess 234Th in underlaying marine sediments. This finding reveals that on the timescale of ~100 days, the 234Th budget in the Bedford Basin is in balance, and no major particle loss is occurring. Using the POC:234Th ratio on sinking particles and integrated 234Th water column fluxes, we report a mean (± s.d.) depositional flux of 20 ± 14 mmol C m-2 d-1 (range 3.6 to 44.5 mmol C m-2 d-1) to the seafloor. This mean flux translates to an annual molar flux of 7.2 ± 0.7 mol C m-2 yr-1, within a factor of 2 to model estimates and previous sediment trap results at this site. Our findings contribute to ongoing research efforts in the Bedford Basin, and aid in the evaluation of coastal regions in local carbon budgets.
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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 | 0.002 | 0.022 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.003 | 0.002 |
| Scholarly communication | 0.005 | 0.004 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.020 | 0.020 |
| Insufficient payload (model declined to judge) | 0.216 | 0.172 |
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".