Exposure of urban ecosystems to Mn and Pb contaminants from gasoline additives beside a major highway in the Greater Toronto Area, Canada
Bibliographic record
Abstract
A study of manganese (Mn) and lead (Pb) deposition in soil was conducted adjacent to a multilane highway in the Greater Toronto Area (GTA), Ontario. The annual average daily traffic (AADT) volume was approximately 333 700 vehicles in 1993. Soil sampling was conducted at two different sites along the highway to determine the concentration and extent of Mn deposition from methylcyclopentadienyl manganese tricarbonyl, MMT (a gasoline additive). Samples were collected at distances up to 160 metres from the roadside, at each site. Parameters evaluated included total and exchangeable Mn and Pb (from historic use of leaded gasoline), soil particle size, pH, and cation exchange capacity. Mn concentrations decreased with increasing distance from roadside. Pb concentrations changed little from values reported in 1990, but have moved deeper into the soil, indicating a cessation of atmospheric deposition. In contrast, exchangeable Mn concentrations decreased with soil depth indicating recent atmospheric deposition. Although Mn concentration in soil decreased with the increase in the distance and the depth adjacent to the multilane highway, the difference was not statistically significant within the sites. More research is needed to provide better understanding of the extent of MMT and the complex behaviour of Mn contamination in the terrestrial urban environment. Key words: manganese, lead, soil, methylcyclopentadienyl manganese tricarbonyl (MMT); gasoline additive; urban environment; greater Toronto area (GTA), Canada
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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 | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".