Experimental evidence that organo-mineral interactions regulate dissolved organic matter bioavailability across permafrost landscapes of the western Canadian Arctic
Bibliographic record
Abstract
The fate of permafrost-origin dissolved organic carbon shapes northern food webs and affects regional and global carbon balances. Substantial variation in Arctic landscapes, and therefore the composition of permafrost sediments, challenges our ability to predict this fate, constraining both knowledge of local-scale effects and upscaling exercises. The western Canadian Arctic is a diverse permafrost landscape shaped by the advance and recession of the Laurentide Ice Sheet, ground ice preservation and development, climate variability, and past thaw and reworking of materials. These factors give rise to significant variation in responses to freshwater dissolved organic carbon (DOC) concentrations and dissolved organic matter (DOM) composition to permafrost thaw. Regional observations of decreased DOC concentrations and increased DOM susceptibility to biodegradation in thaw-impacted fluvial networks suggest that organo-mineral interactions may regulate DOC bioavailability by “protecting” DOM from biodegradation. However, the potential for the formation of organo-mineral interactions in thawed permafrost-affected sediments and their variability across permafrost sediment types is not well understood. Using batch sorption experiments, we assessed sorption potential, water-extractable DOC concentration, and the impact of sorption on DOM composition of six different permafrost sediment types common across the western Canadian Arctic. Sediment biogeochemistry and sorption properties were influenced by geological origin, with increased variation associated with past thaw. Sorption coefficients were positively correlated with organo-reactive forms of Al and Fe and negatively with sediment pH. While all sediment samples showed evidence of DOC sorption, yedoma from the Klondike region had lower sorption coefficients than sediments from regions previously glaciated by the Laurentide Ice Sheet. Exposure to thawed permafrost sediment enabled preferential sorption of larger, humic-like organic compounds and displacement of mineral-bound small, aliphatic molecules, thereby enriching the DOM pool with more bioavailable compounds. Shifts in DOM composition resulted in a corresponding increase in biodegradation. Our experiments demonstrate that organo-mineral interactions are likely to decrease DOC concentration while increasing DOM bioavailability of freshwater ecosystems in response to permafrost thaw, but the strength of this response will vary both across and within landscapes of the permafrost region.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".