Seafloor sediment supply of nutrient silicon on the Greenland margin
Bibliographic record
Abstract
The biogeochemical cycling of nutrient silicon (Si) in the northern high latitudes has received increasing attention over recent years. This is in large part due to the discovery of silicon limitation of diatoms over seasonal timescales, the potential role of melting glaciers in supplying a significant amount of this nutrient to the coastal ocean, and the rapid environmental changes the polar ocean is experiencing as a result of global climate warming. However, our understanding of the nutrient Si in the polar ocean is severely restricted by the lack of knowledge of the benthic Si cycling and its controlling processes, which is due to the limited number of seafloor observations in the region. In this study, we address this knowledge gap through the acquisition of sediment pore water profiles and the execution of incubation experiments on sediment cores collected from the Greenland continental margin and the Labrador Sea. Our results indicate a net (benthic) flux of dissolved silica (DSi) out of the sediment into the overlying seawater at the study sites. A new global compilation also reveals that benthic Si flux observed at our marginal sites are substantially higher than in the open ocean. This is likely because benthic flux in the open ocean is solely maintained by molecular diffusion along a concentration gradient, while there are additional processes: pore water advection and rapid dissolution of certain siliceous sponge groups, and other reactive silica phases, that contribute to the elevated benthic Si flux on the Greenland margin. This finding has important implications for existing evaluations of oceanic Si budgets, which have not accounted for any processes other than diffusion in the global estimation of benthic Si flux. Our results also suggest that strong benthic Si flux observed on the Greenland margin, combined with wind-driven coastal upwelling, could be a significant source of this nutrient to both the diverse (benthic) sponge communities and (planktonic) diatom productivity in the region. The magnitude of this benthic cycling could potentially rival the other continental inputs of Si in the northern high latitudes, as the first estimation of total benthic Si flux from the western Greenland shelf alone (0.04–0.27 Tmol year-1) is in the same order of magnitude as the total Si export from Greenland Ice Sheet (0.2 Tmol year-1) and the pan-Arctic rivers (0.35 Tmol year-1) respectively.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".