Reduction of PCB Contamination in an Arctic Coastal Environment: A First Step in Assessing Ecosystem Recovery after the Removal of a Point Source
Bibliographic record
Abstract
Studies have documented the presence of organic contaminants in Arctic marine environments due to local point sources, but little long-term data is known of the recovery process once those contaminants are removed. In this study, natural recovery of a local marine food web from a historic terrestrial source of polychlorinated biphenyls (PCBs) at Saglek Bay is examined. PCBs were measured in marine sediments, shorthorn sculpin (Myoxocephalus scorpius), and black guillemots (Cepphus grylle) to assess ecosystem recovery over an eight-year period after cleanup of the source. Surface sediment measurements indicate decreases in both the extent and average concentrations of PCBs throughout Saglek Bay. Sculpin collected near the former contaminated beach in 2006 had significantly lower PCB burdens than those collected in 1998/ 99. PCB levels have also decreased significantly in black guillemot nestlings collected from the former contaminated beach area, as well as Island (6-8 km from the source) and Reference (greater than 18 km from the source) locations. This study demonstrates the utility of using indicator species, especially the black guillemot, to monitor PCB uptake in benthic food webs. The rapid decreases in the physical and biotic PCB concentrations from the local ecosystem at Saglek Bay demonstratethe efficiency with which natural ecosystem recovery can take place in a highly energetic coastal marine environment once a chronic contaminant source is removed.
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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 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".