Halogen Production from Playa Dust Emitted from the Great Salt Lake: Implications of the Shrinking Great Salt Lake on Regional Air Quality
Bibliographic record
Abstract
Halogen radicals, such as atomic chlorine (Cl·), can contribute to secondary wintertime fine particulate matter in the Salt Lake Valley. One source of Cl· is the photolysis of nitryl chloride (ClNO 2 ), formed from the reaction of dinitrogen pentoxide (N 2 O 5 ) with chloride-containing aerosol. However, sources of chloride-containing aerosols in the Salt Lake Valley, and their subsequent reaction kinetics, remain poorly constrained. We analyzed playa (i.e., dried saline lakebed) samples collected from dust-emitting regions along the northern and southern areas of the shrinking Great Salt Lake to investigate their mineralogy, reactivity, and ClNO 2 forming potential. The reactive uptake coefficients (γN 2 O 5 ) for all samples ranged from 0.005 to 0.064, with the average γN 2 O 5 of the northern area samples approximately double the average γN 2 O 5 of the southern area samples. We attribute the increased γN 2 O 5 of northern playas to increased particulate chloride and silicate, while the reduced γN 2 O 5 in southern playas is due to particulate organics and high quantities of gypsum, a nonreactive mineral. The yield of ClNO 2 is > 50% for all playas tested, with one exception. Using our kinetic data during an ambient wintertime case study, we estimate playa dust contributes up to 5% of observed ClNO 2, a lower estimate which likely increases during the spring when dust emissions are higher. Our work highlights the importance of including playa dust in current air quality models, especially as reductions of anthropogenic halogen sources are implemented in the United States, and ephemeral lakes continue to shrink globally.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".