Tracing sources of precipitation sulfate in eastern Canada using stable isotopes and trace metals
Bibliographic record
Abstract
Stable isotopic and chemical evidence has been used to trace sources of sulfate in precipitation in eastern Canada and to apportion this sulfate between natural and anthropogenic origins. A site in Nepean, Ontario was chosen to characterize continental inputs from long‐range transport, while two coastal sites in Newfoundland (St. John's and Seal Cove) were chosen to represent the boundary between the marine and continental environments. Precipitation sulfate at the coastal sites should reflect mixing of these two source areas, modified by contributions from local anthropogenic sources. The results of this study show that a three end‐member isotopic mixing model using δ 18 O and δ 34 S describes the composition of sulfate at the Newfoundland sites. The three end‐members are (1) sea spray (δ 34 S = +21‰; δ 18 O = +9.5‰), (2) long‐range transported secondary (anthropogenic) sulfate (δ 34 S ∼ +4‰; δ 18 O ∼ 15‰), and (3) local primary (anthropogenic) sulfate (δ 34 S ∼ +4‰; δ 18 O = +42‰). Mass balance calculations show that as much as 63% of the sulfate deposited at the St. John's site and 18% at Seal Cove is primary sulfate emitted from local pollution sources. Up to 30% of the sulfur deposited in rain at the Newfoundland sites is of continental origin.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 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 teacher head, 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".