Residues of DDT and other selected organochlorine pesticides in soils from Saskatchewan, Canada (1999)
Bibliographic record
Abstract
A study of samples from a broad range of soils across the province of Saskatchewan, Canada, in 1999 has shown evidence that residues of organochlorine pesticides, and in particular DDT [1,1,1-trichloro-2,2- bis(4-chlorophenyl)ethane] and related compounds, are present even after several decades since the last application. In particular, residue levels of total DDT {DDTt = DDT + DDD [1,1-dichloro-2,2- bis(p-chlorophenyl)ethane] + DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene]} in Prince Albert National Park approach some of the highest levels measured to date at non-agricultural locations with concentrations of 119 to 150 ng g-1. Ratios of DDT:DDD:DDE were relatively consistent even from sites separated by several hundred kilometers and seem to be independent of soil properties and sample moisture levels over the region of study. These DDT:DDD:DDE ratios ranged from 9:1:4 for the Prince Albert Park site to 5:1:2 for Agriculture and Agri-Food Canada (AAFC) Research Centres and privately owned agricultural land. Data collected from AAFC Research Centres showed somewhat elevated levels of lindane [γ-1,2,3,4,5,6-hexachlorocyclohexane] (maximum 14 ng g-1), dieldrin [(1R,4S,4aS,5R,6R,7S,8S,8aR)-1,2,3,4,10,10-hexachloro-=6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro- endo-1,4,-exo-5,8-dimethanonaphthalene] (maximum 27 ng g-1) and chlordane [1,2,4,5,6,7,8,8-octachloro-2,3,3a,4,7,7a-hexahydro-4,7-methanoindene] (maximum 10 ng g-1), while samples collected from sites designated as “background” locations demonstrated a minimal effect from long-range atmospheric transport of organochlorines. Key words: Organochlorine residues, soil, Canada, decomposition products, pesticides
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.005 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".