Formation of Brown Carbon from Aqueous-Phase Limonene SOA Reactions with Reduced Nitrogen Species: Effects of Gas-Phase Precursors and Drying Conditions
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Aqueous-phase processing of secondary organic aerosols (SOAs) from limonene oxidation can generate brown carbon (BrC) through reactions with reduced nitrogen species. This study provides laboratory evidence that dark ozonolysis of limonene, in the presence of biogenic (α-pinene) or anthropogenic (toluene) precursors, generates SOAs more effectively in BrC formation when subsequently dried with (NH 4 ) 2 SO 4 /glycine in bulk solutions, and toluene had a stronger effect than α-pinene in promoting oligomeric BrC formation. BrC absorption was significantly enhanced in limonene-SOA and the (NH 4 ) 2 SO 4 /glycine mixed droplet upon evaporation at ∼75% RH but was suppressed at lower RH, likely due to reduced aerosol liquid water and precursor evaporation. RH-dependent trends were also observed in SOA generated by limonene and toluene mixtures (lim/tol-SOA), with the strongest oligomeric BrC absorption at ∼85% RH for both (NH 4 ) 2 SO 4 and glycine systems. While bulk-dried experiments showed 1–2 orders of magnitude differences in BrC absorption between limonene-SOA and lim/tol-SOA, evaporated droplets exhibited no significant differences. This study underscores the importance of studying the effects of SOA precursors, atmospherically relevant drying conditions, and volatility of BrC precursors on the light absorption properties of complex SOAs via aqueous-phase processing.
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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 | 0.000 | 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) | 0.000 | 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 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".