Detecting biogeochemical activity in basal ice using fluorescence spectroscopy
Bibliographic record
Abstract
Abstract Dissolved organic matter (DOM) is an important component of aquatic carbon and nutrient budgets and is a metabolic substrate for organisms at the base of aquatic food chains. Active microbial communities in glaciers affect the abundance and characteristics of organic matter (OM) that is exported to downstream ecosystems. However, how OM is biogeochemically altered in glaciers remains unknown and studies documenting active microbial activity by detecting in situ biogeochemical modifications of OM are lacking due to difficulties characterizing OM and the low concentrations of DOM typical of glacier environments. To address this issue, we measure the abundance and fluorescence characteristics of DOM in basal ice at Victoria Upper Glacier (VUG), McMurdo Dry Valleys, Antarctica. We compare these observations with the results of microbial incubations from the same basal ice samples to determine whether the occurrence of fluorophores indicative of recent microbial activity is linked to the presence of culturable microbial communities containing organisms that could have produced them. Psychrotolerant bacteria were isolated from basal ice samples and were associated with marine humic-like fluorescence. This is interpreted as being indicative of in situ microbial degradation of OM within basal ice at VUG. Marine humic-like material is a recalcitrant form of OM, and its biogeochemical transformation from a relatively labile form of OM in glacier ice may function as a carbon sink.
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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 | 0.000 | 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".