Acidity of Size-Resolved Sea-Salt Aerosol in a Coastal Urban Area: Comparison of Existing and New Approaches
Bibliographic record
Abstract
Aging of sea-salt aerosol and the corresponding phase partitioning behavior of HCl/Cl – were monitored and studied in the Halifax Fog and Air Quality Study (HaliFAQS) field campaign in Canada in the early summer of 2019. Ionic chemical composition of ambient aerosol from total suspended particles (TSPs) to 10 nm was sampled and measured into 14 size ranges, which showed that aerosol at the sampling location was mainly composed of sea-salt constituents with little influence from anthropogenic emissions of secondary inorganic precursors. The size-resolved pH of aged sea-salt aerosol was calculated by Extended Aerosol Inorganic Model (E-AIM) IV and a newly derived method based on the measurement of NH 3 /NH 4 + and HNO 3 /NO 3 – or HCl/Cl – coupled phase partitioning behavior. The latter pH calculation method does not require information about the aerosol liquid water content or complete water-soluble ion measurement, compensating for the role of oxidized organics to influence the proton activity. In comparison, E-AIM calculation requires the input of all major hygroscopic species. The size-resolved pH calculated by E-AIM IV generally agrees with the one calculated by NH 3 –HCl coupled phase partitioning. The sensitivities of HCl and HNO 3 phase partitioning to aerosol pH are studied with both observational data and conceptual modeling, which gives evidence that the phase partitioning of HCl is more sensitive and therefore more reflective of aerosol pH changes than HNO 3 in sea-salt dominated atmospheres where particles typically have pH > 3. The higher concentration and more reliable measurement also make HCl a more suitable choice to track pH changes in this study.
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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 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".