A comparison of methyl and gaseous elemental mercury in the urban atmosphere
Bibliographic record
Abstract
This study was carried out to compare the levels of mercury species, i.e., elemental mercury (Hg°) and methyl mercury (MeHg), in indoor and outdoor air in urban areas in Canada. Offices, laboratories for undergraduate studies, and laboratories for research, in a public building located in the downtown core of the city of Toronto, were selected. Hg° was measured using an automated mercury vapour analyzer. MeHg in the air was collected using a carbotrap, and the trapped MeHg was thermally desorbed and analyzed using a CVAFS. The results showed that both indoor MeHg and Hg° levels were related to location function and air circulation. Outdoor MeHg levels were significantly elevated, ranging between 21 and 41% of total mercury (THg) levels, compared to those reported from previous studies. Outdoor Hg° fluctuations were not found to be significantly related to temperature or sunlight exposure, and outdoor MeHg levels were connected to soil and vegetation abundance. Average indoor Hg° levels were found to be between 1.4 and 15 times higher than outdoor levels, whereas MeHg indoor levels were not consistently higher than outdoor levels. Although the mercury concentrations in the indoor environment are still lower than the safety standard for Hg° and organic mercury, they are comparable to those observed near point sources. Thus, indoor air can be a source of mercury to the atmosphere.
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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 | 0.000 | 0.000 |
| 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".