Bioindication of atmospheric heavy metals in the lower Fraser Valley, B.C., Canada
Bibliographic record
Abstract
The atmospheric heavy metal content of the Fraser Valley, B.C., Canada was assessed for 1993 by analyzing lead, cadmium, chromium, nickel, zinc, and manganese content in 62 samples of the common woodland moss Isothecium stoloniferum Brid. Lead, cadmium, nickel and zinc showed a correlated regional distribution with high values in the western more urbanized areas and lower values in the rural eastern areas. Chromium and manganese exhibited a less distinct distribution pattern. Highest values were recorded for the North Shore Mountains relating to increased precipitation and pollutant transport by the local wind pattern from industrial areas in the Port Moody, Burnaby area, where metal readings reached another maximum. Relationships of these findings to population density, land use, traffic and industrial activity were investigated. Historical changes of metal levels in the ambient air of the study area since the early 1960s were examined through analysis of moss specimens from the U.B.C. herbarium. Metal pollution patterns were established for the periods 1960 - 1966 and 1975 - 1980. In addition, changes in metal levels in moss samples from three sites with a continuous collection record since the 1960's are described. A general decline in atmospheric levels for lead, cadmium, chromium, nickel, and zinc was found. The observed decrease reflected the reduction of heavy industries in the area, abandonment of leaded gasoline and the change from oil to gas and elecuicity for space heating. Reduction in atmospheric metals, as determined by the moss method, reflected the general decline in particulate .emission, as determined by the GVRD direct air sampling program. Manganese levels, in contrast, have increased since the 1960s, which might be attributed to the addition of Methylcyclopentadienyl manganese tricarbonyl (MMT) to gasoline, replacing the leaded antiknock additives. Comparisons were made to recent metal levels and historical changes reported from European 'moss method' studies. The potential of the 'moss method' to be used for general air quality assessments was investigated, by comparison to direct air quality measurements of various pollutants and a general air quality index.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".