DRIVERS OF ISOTOPIC AND GEOCHEMICAL VARIABILITY IN SUBARCTIC PERMAFROST WATERSHEDS
Bibliographic record
Abstract
Northern environments are undergoing rapid hydrological and geochemical transformations as warming temperatures and changes in precipitation regimes accelerate permafrost thaw. In permafrost-influenced catchments, seasonal thaw regulates vertical and lateral hydrological connectivity of the catchment to the stream, yet there is considerable variability across watersheds reflecting differences in permafrost status, topography, lithology and vegetation. Despite widespread reports of permafrost degradation, uncertainties in the future trajectories of cold regions remain due to limited field-based studies that characterize runoff generation processes across diverse spatiotemporal scales. This study integrates six years of isotopic, hydrochemical and high frequency datasets collected from seven catchments in the Tombstone Waters Observatory, Yukon, to evaluate how seasonality, catchment structure, and lithology influence water storage and runoff mechanisms. Results revealed strong seasonal evolution in source water contributions and flowpath activation. Continuous permafrost catchments showed high isotopic variability in δ²H and δ¹⁸O, strong event signals, and low solute concentrations, consistent with shallow flowpath dominance and minimal subsurface storage. In contrast, lower permafrost extent catchments exhibited reduced isotopic variability, muted event signals, and higher solute concentrations, reflecting enhanced groundwater contributions and greater storage capacities. Observed seasonal and spatial variation in solute concentrations (up to 2 orders of magnitude), Mg2+/Ca2+ and (Ca²⁺ +Mg²⁺) / SO₄²⁻ molar ratios, and concentration-discharge relationships highlight the combined role of permafrost extent in constraining water-rock interaction, and lithology in governing mineral weathering processes and geochemical signatures. High frequency data revealed threshold shifts in subsurface connectivity following late-season storm events, and increased complexity in paired concentration-discharge relationships that reflect subsurface heterogeneity. The findings of this study demonstrate that hydrologic and geochemical variability in subarctic catchments emerge from interacting influences of storage capacity, catchment structure, and lithology. By capturing both seasonal and event scale dynamics over variable catchment characteristics, this work provides new insight into the processes shaping runoff generation and chemical regimes in northern headwaters, and their potential response to climate change.
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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 | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".