Distribution and persistence of DDT in soil at a sand dune-marsh environment: Point Pelee, Ontario, Canada
Bibliographic record
Abstract
DDT was applied at Point Pelee, Ontario, Canada, between 1948 and 1970 for mosquito control in recreational areas and pest control in former agricultural areas. Recent soil sampling programs produced 275 analyses enabling a statistical comparison of DDT concentrations with land use areas, soil conditions, and hydrologic characte ristics. Concentrations of ΣDDT ranged over several orders of magnitude, with the highest concentrations (maximum 316 000 ng g -1 ) in former agricultural areas and the lowest concentrations in the natural sand dunes (maximum of 116 ng g -1 ). DDT is undergoing degradation at Point Pelee along two pathways. DDT is transformed aerobically to DDE within the sandy soils exhibiting average %DDT, %DDE and %DDD of 40%, 55%, and 5% of ΣDDT, respectively. DDT is transformed anaerobically to DDD and DDE within the marsh and flooded soils averaging 14% DDT, 44% DDE, and 42% DDD, respectively. The half-lives for the transformation of DDT to DDE within the well-drained and aerobic sandy soils at Point Pelee are highly variable and were estimated to range from 20 to 50 yr. Given the high concentrations of ΣDDT at Point Pelee and the long half-life, it is expected that DDT will remain at concentrations of concern for many decades. Key words: DDT, persistence, degradation rates, concentrations, sandy soil, marshy soil
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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 | 0.000 | 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".