Sources and Cycling of Particulate Organic Matter in Baffin Bay: A Multi-Isotope δ13C, δ15N, and Δ14C Approach
Bibliographic record
Abstract
The Canadian Arctic is warming three times faster than the rest of the planet. The impact of climate change on the Arctic carbon cycle, and in particular for Baffin Bay, remains poorly constrained. Sinking particulate organic matter (POM sink ) is a key component of the biological carbon pump and provides a direct linkage between surface productivity and the preservation of carbon in marine sediments. While POM sink provides a rapid POM shunt to the deep ocean (days) the majority of marine POM is suspended (POM susp ) persists for years in the water column. Stable carbon (δ 13 C), nitrogen (δ 15 N) and radiocarbon (Δ 14 C) measurements are powerful tools for evaluating sources and cycling of POM. In this study, we measure depth-integrated (0-400m) POM susp stable carbon (δ 13 C), nitrogen (δ 15 N) and radiocarbon (Δ 14 C) values at 11 stations in Baffin Bay. We use POM C:N a ratios to evaluate its diagenetic state. POM susp δ 13 C and δ 15 N values ranged from −21.6‰ to −29.5‰, and +3.84‰ to +7.21‰, respectively. POM susp Δ 14 C values ranged from −41.8‰ to +76.8‰. Together, our results suggest Baffin Bay POM susp has multiple carbon and nitrogen sources. POM susp δ 13 C and Δ 14 C are strongly correlated to surface salinity, indicating surface water has a strong influence on POM susp isotopic composition and 14 C-age. POM susp from coastal Greenland stations have similar Δ 14 C values to surface dissolved inorganic carbon (DIC) and POM concentrations, consistent with primary production as the predominant POM susp source in Eastern Baffin Bay. Positive POM susp Δ 14 C values in central Baffin Bay suggest an accumulation of atmospheric “bomb” 14 C in the sub-polar gyre. POM susp exiting Davis Strait via the Baffin Island Current was determined to have a significant degraded, resuspended sediment component. Finally, POM susp δ 15 N values highlight two distinct N sources in Baffin Bay: Pacific and Arctic nutrients at Northern gateway stations vs. the influx of Atlantic nutrients via Davis Strait along coastal Greenland. Overall, these first Baffin Bay POM susp Δ 14 C values provide useful baseline data for rapidly changing Arctic ecosystem.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.002 |
| 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 teacher head, 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".