Simultaneous Gas and Particle Phase Measurements Facilitate the Understanding of Ammonia's Atmospheric Budget
Bibliographic record
Abstract
Abstract Ammonia is an important gaseous air pollutant with many direct and indirect negative effects on human and ecosystem health. The thermodynamic equilibrium between the ammonia in the gas phase and the ammonium ion in the condensed phase complicates the understanding of its ambient concentrations. In this study, long‐term historical data of ammonia concentrations and particle composition at 10 sites from Canada's National Air Pollution Surveillance program was used to show that the simultaneous analysis of both measurements is crucial for properly understanding ammonia's atmospheric budget. Over the multiyear observation period, the ammonia concentration displayed a positive slope or no trend in all sites, while the NHx (sum of ammonia and ammonium) concentration remained almost constant in most sites, and the fraction of NHx in the gas phase increased; that is, the apparent trend in ammonia depends not only on source and sink processes but on the atmospheric conditions that control the gas‐particle equilibrium. Under these circumstances, generalizations about the trends may be incorrect if either the ammonia or ammonium is analyzed in isolation due to their different deposition rates. The comparison of measurements with the output from the GEOS‐Chem High Performance model shows that the seasonality of the ammonia emission inventories and, consequently, the ammonia budget in the model needs to be revised. This work underscores the need for more sites monitoring ammonia concentrations simultaneously with particle composition to understand the temporal and spatial variability and effects of ammonia.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| 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".