Particulate Trace Metals in Arctic Snow, Sea Ice, and Underlying Surface Waters during the 2015 US Western Arctic GEOTRACES Cruise GN01
Bibliographic record
Abstract
Sea ice, an intrinsic component of the Arctic system, is undergoing rapid change. Sea ice dynamics play a role in the distributions of trace metals in Arctic waters through the incorporation, transport, and release of particles derived from atmospheric, sedimentary, and biological sources. Particulate (>0.2 μm) trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba, and Pb) were measured in Arctic pack ice, associated snow, and underlying surface waters collected from September to October 2015 during the US GEOTRACES Western Arctic cruise (GN01). Sampled ice contained low sediment loads, was permeable, and had undergone desalination prior to collection. To assess the lability and refractory nature of particles from snow, sea ice, and underlying surface waters, samples were subjected to an acetic acid leach solution prior to complete digestion. In general, snow particles were of lithogenic origin, with enrichment of Co, Ni, Cu, and Zn at one station in the Canada Basin. Lower than expected particulate metal loads were observed within the sea ice matrix at all stations. Our measurements of the top 1 m of the ice column yielded higher loads for Al, and Fe (88 and 23 μmol m–2, respectively), intermediate loads for Mn, Zn, and Ba (0.82, 0.38, and 0.12 μmol m–2, respectively), and lower loads for Co, Ni, Cu, Cd, and Pb (20, 50, 40, 1, and 20 nmol m–2, respectively). Because sediment-laden “dirty ice” was not sampled during this study, these values likely reflect the lower range of particulate metal loads in Arctic sea ice. To determine heterogeneity at the meter-scale (within station) vs the mesoscale (among stations) multiple cores were collected at each sea ice station. Particulate Al and Fe were the only two metals with a discernible pattern of greater heterogeneity at the mesoscale for the sampled ice. These two metals also showed a distinct atmospheric source, while Cd and Pb appeared to have a source from the surface seawater below the ice. Except for Fe, labile particulate metals were close to, or at, the detection limit. Low leachable particulate metal fractions in snow and sea ice could reflect prior in situ leaching of particles in contact with brine pockets and/or a consequence of procedural artifacts during melting. As multiyear ice becomes less abundant in the Arctic Ocean, the reservoir of particulate metals previously exported to the North Atlantic via sea ice will instead be released within Arctic waters during the melting season, impacting dissolved metal loads and the export of particulate metals.
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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 | 0.000 | 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".