Observation of high sediment concentrations entrained in jumble river ice
Bibliographic record
Abstract
Abstract Ice formation is generally considered to exclude many particles and most solutes and thus be relatively pure compared to ambient waters. Because river ice forms by a combination of thermal and mechanical processes, some level of sediment entrainment in the ice column is likely, though reports of sediment in river ice are limited. We observed high and sporadic levels of silt and sand in ice of the Kuskokwim and Tanana rivers (Alaska, the United States) during routine field studies. These observations led us to make a more comprehensive survey of sediment entrainment in river ice of the Kuskokwim and Yukon rivers and several of their tributaries. We collected and subsampled 48 ice cores from 19 different river locations in March 2023, which included concurrent measurements of water turbidity, velocity, and depth. Approximately 60% of cores contained detectable levels of sediment, averaging 438 mg/L with median concentrations exceeding 1000 mg/L in three cores from the Yukon and Kuskokwim main stems. Many cores had even higher concentrations at certain intervals, with seven cores having subsamples exceeding 2000 mg/L; these were often located in the middle or lower portion of the ice column. Jumble ice, formed mechanically by frazil‐pan jamming during freeze‐up, was generally the best predictor of higher sediment entrainment, and these locations often had higher under‐ice velocities and depths. Our observation of high and widespread sediment entrainment in northern river ice, particularly in jumble‐ice fields, may have implications for sediment transport regimes, ice strength and transportation safety, and how rivers break up in the springtime.
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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 | 0.001 |
| 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".