Physical and Biogeochemical Influences on Nutrients Through the Canadian Arctic Archipelago: Insights From Nitrate Isotope Ratios
Bibliographic record
Abstract
Abstract The Canadian Arctic Archipelago (CAA) provides a gateway for the flow of nutrients from the North Pacific to the North Atlantic. The transport and biogeochemical cycling of nutrients throughout the CAA, however, are sparsely documented. Here, we report water column nitrogen and oxygen isotope ratios of nitrate (δ15NNO3 and δ18ONO3) collected in a throughflow of the CAA into Baffin Bay, providing insights on inherent nutrient dynamics. The nitracline shoaled eastward into the CAA, wherein large subsurface chlorophyll maxima and coincident increases in δ15NNO3 and δ18ONO3 indicated enhanced nitrate assimilation relative to the oligotrophic Canada Basin. High δ15NNO3 values characteristic of Pacific Winter Water (PWW) pervaded the Archipelago and Baffin Bay, decreasing eastward due to mixing with underlying Atlantic water (AW)—from the Canada Basin west of Barrow Strait, and from Baffin Bay east thereof. Nearly 25% of nutrients in the central CAA were of Atlantic origin, a substantially larger fraction than surmised previously. Nutrient properties in the CAA were notably not influenced by benthic denitrification. Those in underlying AW in the western CAA, however, were modified by remineralization of Pacific‐sourced nutrients, manifested from increases in δ15NNO3 relative to the Canada Basin. Properties in the eastern CAA exposed the complex hydrography of Baffin Bay, characterized by lateral intrusions of nutrient‐poor winter waters into PWW and of cold mode waters in underlying AW. High δ15NNO3 values in AW revealed the presence of a substantial fraction of N from remineralization, stemming from the high productivity in Baffin Bay fueled by Pacific nutrients.
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 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".