Exposure to mercury and Aroclor 1268 congeners in least terns (Sternula antillarum) in coastal Georgia, USA
Bibliographic record
Abstract
Concentrations of total mercury and the rare PCB mixture Aroclor 1268 in least terns (Sternula antillarum), a colonially-nesting, piscivorous seabird, in the Turtle River estuary and other coastal sites in Georgia, USA, were investigated. The Turtle River estuary is the location of the Linden Chemical Plant (LCP) Superfund site, a site prioritized by USA law for immediate remediation, where industries released effluent containing these contaminants until 1994. Aroclor 1268 is a highly-chlorinated PCB mixture that was used and released exclusively at the LCP site and nowhere else in the south eastern USA. High concentrations of Aroclor 1268 congeners and mercury have been documented in biota local to LCP, but no studies report concentrations in high trophic level, piscivorous birds such as least terns. We collected feathers and feces from chicks, and eggs from adults, at nesting colonies along the Georgia coast to analyze contaminant loads (in dry weight ppb). Mean Aroclor 1268 mixture concentrations in eggs (≤16,329 ppb) were highest at colonies in and just outside LCP, and decreased with increasing distance (up to 110 km) from LCP, but the Aroclor 1268 signature congener mixture was present at all sites. Mercury concentrations in eggs (≤3370 ppb), feathers (≤5950 ppb), and feces (≤417 ppb), were present at all sites, but did not vary significantly among sites. This report confirms the extensive dispersal of Aroclor 1268 congeners (approximately 110 km north and 70 km south of its point source) via bioaccumulation and trophic transfer.
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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 | 0.000 |
| 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 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".