Deposition of Mn from Automotive Combustion of Methylcyclopentadienyl Manganese Tricarbonyl beside the Major Highways in the Greater Toronto Area, Canada
Bibliographic record
Abstract
Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used in Canada since 1976 as an antiknock agent in gasoline, completely replacing Pb in 1990. An early study of much higher Mn concentrations in gasoline showed that the combustion of MMT leads to the formation of inorganic manganese oxides, especially Mn3O4. Recent emission testing by Lawrence Livermore National Laboratory for Ethyl Corp. has shown that Mn is primarily emitted as a phosphate or sulfate along with minor amounts of oxides. The main objective of this research was to analyze the deposition of Mn from MMT to the terrestrial environment beside the major highways in the greater Toronto area (GTA), Canada. The results were compared with Pb and other trace elements such as Al, Ca, Fe, Mg, Cu, Zn, Na, and the Cl ion (water extractable) to study the behavior of Mn in soil. The study area was located near major Toronto highways 401 (urban) and 400 (rural), at 43 degrees 67' N and 79 degrees 37' W (latitude and longitude) (278,560 and 47,835 cars/day), respectively. Surface soil samples (0-5 cm depth) were collected at distances up to 40 m from the roadside. Parameters evaluated included total and available Mn and other trace elements, particle size, pH, organic content, and cation exchange capacity. Based on high traffic density along 401, higher Mn deposition was expected. No significant differences were found between the 401 and 400 Barrie (E(+1)) sites, attributable to the natural background levels of Mn or its contribution by other sources such as Mn-enriched road dust or naturally occurring crustal Mn. However, the 400 King City (E(+2)) site had significantly lower Mn levels than did the other three sites, 401 and 400 Barrie. This may be explained by the types of soil along the 401 and 400 sites. The King City site along 400 was found to be higher in sand content than were the 401 sites. A higher sand content could result in higher leaching of Mn to the bottom layer of the soil. Although MMT has been used continuously for approximately 25 years in Canada, its contribution to the terrestrial environment has been very low and has not significantly increased Mn levels along the highways, as demonstrated by this study.
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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 | 0.002 | 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 | 0.001 | 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".