Biomass burning organic aerosol (BBOA) from wildfires has multiple phases and is more viscous than laboratory generated BBOA
Bibliographic record
Abstract
Biomass burning organic aerosol (BBOA) is a major contributor to organic aerosol in the atmosphere. The impacts of BBOA on climate and health depend strongly on their physicochemical properties, including viscosity and phase behaviour (number and types of phases); these properties, and their relationships to BBOA chemistry, are not yet fully characterized. We collected BBOA field samples during the 2021 British Columbia wildfire season to constrain the viscosity and phase behaviour at a range of relative humidities, and compared them to laboratory generated BBOA made from smoldering pine wood. Particles from all samples exhibited two-phased behaviour with a higher polarity hydrophilic core and a lower polarity hydrophobic shell. We used the poke-flow viscosity technique to estimate the viscosity of the particles. We found that both phases of the field samples had viscosities >10 8 Pa s at relative humidities up to 50%, which is more viscous than any laboratory generated BBOA or BBOA proxies previously measured. Aerosol mass spectrometry showed that the field samples were more oxidized than those generated in the lab, which is a likely explanation for the higher viscosity. The two phases and high viscosity have implications for how BBOA should be treated in atmospheric models
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".