Discerning Trends in Wintertime Reactive Chlorine Chemistry And Air Quality
Bibliographic record
Abstract
Reactive chlorine species (Cl*) are crucial to atmospheric chemistry, impacting oxidative cycles, pollutant formation, and air quality. However, their behavior, particularly in urban winter environments, remains underexplored. This thesis investigates the sources, transformations, and impacts of reactive chlorine in urban settings using high-time-resolution measurements, size-resolved aerosol analysis, and advanced modeling techniques. High-time-resolution measurements of hydrogen chloride (HCl) were conducted in coastal (St. John’s, NL) and continental (Toronto, ON) regions. In the coastal environment, HCl variability was influenced by photochemical and acid displacement processes, while in Toronto, direct emissions dominated, with road salting contributing to particulate chloride but not directly to HCl production. Simulations using GEOS-Chem captured coastal variability but significantly underestimated urban HCl levels, indicating the complexity of urban chlorine sources. Size-resolved aerosol analysis during road salt application revealed that chloride levels in urban aerosols were similar to marine environments, with road salt-derived chloride redistributed into finer aerosol modes. These findings suggest that acid displacement and heterogeneous reactions play a critical role in sustaining HCl production over time. Simulations with the E-AIM model underscored the need for improved representation of ammonia and ammonium chloride chemistry to predict HCl partitioning more accurately. Indoor sources, particularly chloramines (NH₂Cl, NHCl₂) from hypochlorite-based cleaning products, were identified as significant outdoor contributors to reactive chlorine budgets. These sources were found to rival smaller industrial emissions. Mobile and vertical gradient measurements quantified spatial variability in HCl emissions, highlighting the influence of local meteorological conditions on HCl fluxes and deposition. These findings advance our understanding of urban chlorine chemistry, providing insights into sources, transformations, and their implications for air quality and atmospheric models.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.002 |
| Open science | 0.000 | 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 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".