Bioavailable Organochlorine Pesticides in a Semi-Arid Region of Eastern Oregon, USA, as Determined by Gas Chromatography with Electron-Capture Detection
Bibliographic record
Abstract
A group of dissolved-bioavailable organochlorine (OC) pesticides and inorganic anions in water and total OC pesticides in sediments were measured in the Malheur Watershed, a semi-arid region in the western United States, over a 2-year period. OC pesticide levels were compared with those from a 1990 study of the lower section of the river, the most recent data available. After calculating the dissolved fraction from the 1990, study it seems that DDD and dieldrin levels have decreased in the water by 50-70%, while DDE and DDT have changed little. Although banned nearly 30 years ago, DDT is still persistent throughout the Malheur River basin/watershed because it was found in all water samples tested. All of the OC pesticides tested during the 2-year study are well below the criterion continuous concentration for aquatic community exposure as defined by the U.S. Environmental Protection Agency (EPA). OC pesticides appear to be decreasing, however, at lower Ontario there remains a human health risk (EPA Human Health Risk Water Quality Criteria) for DDT, because this criteria includes daily consumption of water and fish from the river. Overall, although the upper forest watershed sites have lower OC pesticide concentrations, they represent an important contribution to the total DDT load to this watershed, a source not previously acknowledged. The large increase in DDT and sigmaDDT between the Ontario sites may indicate a possible historical point source of contamination or historical preferential deposition of contamination. Normalized sediment (sigmaDDT/organic carbon) strongly correlates with dissolved water sigmaDDT.
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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 | 0.000 | 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) | 0.000 | 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 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".