Source characterization of ambient fine particles in the Los Angeles basin
Bibliographic record
Abstract
Integrated 24 h PM 2.5 (particulate matter ≤2.5 µm in aerodynamic diameter) speciation data collected between 2001 and 2004 at three United States Environmental Protection Agency Speciation Trends Network monitoring sites in the Los Angeles (LA) basin (Simi Valley, downtown LA, and Rubidoux) were analyzed through the application of the positive matrix factorization and seven to nine sources were identified. Secondary particles provided the highest contributions to PM 2.5 concentrations (29%–46% for secondary nitrate and 12%–23% for secondary sulfate). Rubidoux, which is located downwind of the LA metropolitan area, and animal feed lots had the highest secondary nitrate concentration, followed by downtown LA. Secondary sulfate concentrations were consistent among three sites. Gasoline vehicle and diesel emissions contributed 12%–22% and 7%–10%, respectively. In addition, other sources such as airborne soil, sea salt, aged sea salt, wood smoke, and incinerator emissions were identified. Key words: source apportionment, Los Angeles basin, speciation trends network, PM 2.5 .
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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 | 0.001 | 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".