Exploring The Relationship Between Particle & Gas Phase Chlorine In Continental Winter
Bibliographic record
Abstract
Road salt is widely used in many North American and European urban wintertime environments yet its impacts on tropospheric reactive chlorine species are still uncertain. We present ambient size-resolved particle-phase chloride (Cl-) and hydrogen chloride (HCl) measurements that were made in continental urban winter (Toronto, ON) concurrent with several applications of road salt. We also show long-term monitoring of Cl- and Na+ (road salt ions) mass loadings from local National Air Pollution Surveillance (NAPS) stations in Toronto. Long-term levels of road salt ions were higher by a factor of 3.7±1.5 and 2.9±0.9, respectively, during winter months (December-March) in comparison to summer months (May-September). Cl- mass loadings from stations as well as size-resolved measurements rival those observed in coastal/marine environments. Cl- mass fractions were 32±9 % and 8±3 % of the coarse and fine mode, respectively. Although Cl- levels were comparable to those in coastal locations, HCl mixing ratios were lower, ranging from <4-896 parts per trillion by volume (pptv). Fresh application of road salt did not directly lead to elevated HCl, presumably due to sufficient pre-existing Cl- throughout the contaminated urban environment. A thermodynamic model (E-AIM) was used to assess the contribution of HCl partitioning to observed mixing ratios using measured levels of key particulate and gas phase species. Simulations showed that HCl partitioning was a minor contributor to observed HCl levels under low-temperature winter conditions. Particles in both the coarse and fine mode were Cl- deficient, providing evidence for repartitioning of Cl- from the coarse to the fine mode.
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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 | 0.000 | 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 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".