Assessing permafrost erosion in the Canadian Beaufort Sea, Herschel Island - A biomarker and radiocarbon approach
Bibliographic record
Abstract
Terrestrial organic matter (terrOM) stored in high latitude permafrost soils represents one of the largest carbon pools on Earth. This pool of carbon is highly vulnerable to climatic changes, due to its susceptibility to mobilization during permafrost thawing, increasing river discharge and sea level rise. The release and transport of pre-aged terrOM from permafrost regions to the Arctic Ocean potentially triggers important feedback mechanisms including increased greenhouse gas emissions. Despite its importance, terrOM fluxes to the Arctic Ocean are poorly investigated and processes effecting the fluxes are ill-constrained. The main driver for terrOM flux in permafrost regions is coastal erosion, which currently releases 14 Tg of terrOC per year into the whole Arctic Ocean. Nevertheless, these estimations and related climate models disregard/underestimate terrOM burial rates for nearshore regions and basins that are considered as carbon and nutrient sinks. Detailed carbon, nutrient and sediment budgets for nearshore zones and basins however do not exist. \nTo illustrate the importance of nearshore regions for global carbon fluxes we investigated the OM composition of the small, shallow nearshore Herschel Basin, located in the Beaufort Sea. The basin receives OM from marine primary production, coastal erosion (of the Yukon Coast and Herschel Island) as well as from the Mackenzie River. The so far unknown relative contributions of these sources to the basin is of vital importance to understand the regional carbon fluxes. In order to quantify the relative contributions the lipid composition, bulk d13C values and radiocarbon ages of the sources were determined to characterize and define individual endmembers. The same properties were determined for 20 sediment samples and 1 sediment core retrieved from the basin and a Monte Carlo simulation was performed to calculate the relative contributions based on a dual carbon approach and lipid endmembers. \nResults indicate that surface sediment OM in the basin is very old (~20 ka) and of predominantly terrestrial origin. Approximately 60% of the OM in the basin can be assigned to eroded material from the nearby Herschel Island, illustrating the importance of permafrost thawing and coastal erosion to the carbon budget off nearshore zones. Further, enhanced burial rates and increased terrOM supply observed in the sediment core suggest intensification of coastal erosion over the recent decades.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".