Singlet oxygen and triplet excited state organics produced by primary biomass burning organic aerosol from wood, dung, straw and plastic fuels: Role of solvent-dependent photochemistry
Bibliographic record
Abstract
Biomass burning organic aerosol (BBOA) is a significant source of brown carbon (BrC), a class of light-absorbing organic compounds that influence climate and atmospheric oxidation chemistry. Certain BrC chromophores act as photosensitizers by producing reactive oxidants such as singlet oxygen (SO) and triplet excited states (TP) upon solar irradiation, but we still cannot predict which functional groups drive the production of these excited state oxidants. We hypothesized that since the major sink for SO is solvent deactivation, water-based extractions of chromophores may (1) underestimate SO production in BBOA, as well as (2) overlook water insoluble chromophores potentially important in hydrophobic aerosol phases. To better represent the multiphase nature of atmospheric aerosols in this work, we employed a co-solvent extraction using acetonitrile and water to extract the hydrophobic fraction of BrC chromophores. Primary organic aerosol (POA) filters from the combustion of beechwood, cow dung, straw, and plastic were collected during the BAMBE campaign, and subsequently analyzed using a two-probe photochemical method with furfuryl alcohol and syringol as probes to quantify SO and TP steady-state concentrations and quantum yields, respectively, under UVA irradiation. The acetonitrile-water mixture enhanced chromophores recovery and modulated the quenching of the excited state of SO back to O2, leading to up to a six-fold increase in SO concentrations. Fuel type significantly influenced oxidant yields; beechwood and plastic extracts showed the highest SO and TP production, up to 4.9 ±0.1% for SO and 4.2 ±0.2% for TP. Complementary FIGAERO-CIMS analysis revealed compositional differences between fuels and combustion conditions, suggesting nitrogen-containing species drove the variability in sensitization efficiency. Our findings underscore the importance of solvent selection and fuel source in assessing BrC photochemical activity and offer new insights into the oxidative potential of BBOA in atmospheric multiphase environments.
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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".