Three approaches to define the ecotoxicity threshold for atmospheric ammonia
Bibliographic record
Abstract
Atmospheric NH 3 is potentially toxic to terrestrial plants, and there are other environmental effects such as haze from (NH 4 ) 2 SO 4 aerosols and N enrichment of ecosystems that are normally very low in N. Toxic levels can arise from atmospheric releases from livestock operations. Plants detoxify NH 3 by incorporation of the N into the plant, so direct toxic effects are most likely when plants are growing slowly, as in cold weather. Indirect effects include leaching of nitrates and cations, and cation imbalances, and are most likely in N-poor, non-agronomic settings. The concentrations in air that cause direct toxic effects were summarized, and the corresponding "expected no effect value" (ENEV) was established at 35 nmol NH 3 mol -1 (48 µg m -3 ). Critical loads, the threshold flux density of NH x -N to the landscape that causes detrimental effects, were also summarized. The critical load was 10 kg N ha -1 yr -1 . Using deposition velocity values from the literature (0.3 to 3.6 cm s -1 ), the ENEV implies a load flux of 24 to 290 kg N ha -1 yr -1 . This is above the critical load, suggesting that critical loads to the landscape are more limiting than are direct toxic effects on plants. Another novel approach was to define an ENEV as the mean compensation point (ENEV cp ). Compensation point is the atmospheric concentration below which plants emit NH 3 and above which they absorb NH 3 . Compensation point data were summarized and the ENEV cp was established at 3.7 nmol mol -1 (5.1 µg m -3 ). This coincides with a load flux of 4.8 to 58 kg N ha -1 yr -1 , more consistent with the critical loads. Key words: Priority Substance List, compensation point, ammonia toxicity, atmospheric ammonia
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".