Background atmospheric sulfate deposition at a remote alpine site in the Southern Canadian Rocky Mountains
Bibliographic record
Abstract
Abstract We report observations of stable isotope ratios and ion concentrations from seasonal snowpack and summer bulk precipitation from remote alpine sites in the Southern Canadian Rocky Mountains. Spatial deposition patterns for sulfur (S) and δ34S‐SO42− values indicate dominantly distant sources with little impact from local to regional pollution. Comparable S loads and total snowpack δ34S‐SO42− values for glacier snowpack indicates S emissions were well mixed prior to dry deposition or incorporation into snowfall. A uniform S load and similar δ34S‐SO42− values in a detailed study of summer bulk precipitation implies well‐mixed distant emissions. We interpret the deposited 0.9 kg S ha−1yr−1 as atmospheric background deposition in midlatitude Western Canada. This study will improve calculations for sites impacted by point source emissions and provide a baseline for attributing changes associated with climate change, industrialization, and urban growth. Field evidence from this study supports theoretical and laboratory research on the relative importance of oxidation pathways on atmospheric δ34S‐SO42− values for long‐range transported sulfate. δ34S‐SO42− of the dominant S source in summer bulk precipitation (~ +2‰) versus snowpack (≥ +9‰) cannot be explained by seasonal emission sources, temperature effects on fractionation, or Rayleigh distillation. The study supports a seasonal difference in the relative importance of the different SO2 to SO42− oxidation pathways with homogeneous oxidation by OH and heterogeneous oxidation by H2O2 most important in summer, and O2 catalyzed by transition metal ions in a radical chain reaction pathway more significant in winter.
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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 | 0.001 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".