Polychlorinated Naphthalenes in the Atmosphere of the United Kingdom
Bibliographic record
Abstract
Archived extracts from two air sampling campaigns were used to investigate PCNs in the U.K. atmosphere. In the first study, daily air samples were collected at a semi-rural location (Hazelrigg) in northwest England in 1994. Air parcel back-trajectories were used to distinguish air masses that stemmed from distinct sectors, and 18 samples representing four regions (Arctic/Scandinavia; Atlantic; mainland Europe; U.K.) were selected for PCN analysis. The mean for all samples was ∑PCN = 59 pg m -3 and ∑PCN/∑PCB = 0.31 with a profile that was dominated by the 3-Cl and 4-Cl PCN homologue groups. Atmospheric concentrations of PCN and the ratio ∑PCN/∑PCB were lowest for samples that had trajectories that stemmed from the Arctic/Scandinavia sector—20 pg m -3 and 0.24, respectively. Highest values were observed for air that lingered over the U.K. before arriving at the sampling site—108 pg m -3 and 0.41, respectively. These results are consistent with elevated PCN burdens in the eastern Arctic Ocean for air samples that stemmed from the U.K. region and suggest that the U.K. is a significant emission source of PCNs. On the basis of this study, we also conclude that a ∑PCN/∑PCB ratio of 0.2−0.25 is characteristic of background air resulting from diffuse emission sources and that a ratio much greater than 0.25 indicates an increasing contribution from “nondiffuse” or “point sources” of PCNs. In the second study, extracts were obtained for 1998−1999 from four stations operated under the TOMPS monitoring program—Manchester (urban), Hazelrigg (semi-rural), Stoke Ferry (rural), and High Muffles (rural). PCN air burdens were highest at Manchester (138−160 pg m -3 ) and decreased to ∼22−35 pg m -3 at the rural sites.
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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 | 0.001 |
| Science and technology studies | 0.000 | 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".