Polybrominated Diphenyl Ethers in Air across China: Levels, Compositions, and Gas-Particle Partitioning
Bibliographic record
Abstract
Air samples were concurrently collected using high volume air samplers for 24 h every week from September 2008 to August 2009 at 15 sites (11 urban, 1 suburban, and 3 background/rural) across China. Twelve polybrominated diphenyl ether (PBDE) congeners (BDE-17, -28, -47, -66, -85, -99, -100, -138, -153, -154, -183, and -209) were measured. Total PBDE concentrations (∑12PBDEs) in air (gas + particle phases) were in the range of 11.0-838 pg m(-3) with a mean of 232 ± 72 (mean ± SE) pg m(-3). The site with the highest concentration was Guangzhou (838 ± 126 pg m(-3)), followed by Beijing (781 ± 107 pg m(-3)). Significant positive correlations were found between PBDEs levels and urban population (R = 0.69, P < 0.05) and gross industrial output values (R = 0.87, P < 0.001) as well. BDE-209 was the dominating congener with the contribution of 64 ± 23% to ∑12PBDEs, followed by BDE-47(8 ± 8%) and -99(6 ± 5%) at all urban and suburban sites. At background/rural sites, however, BDE-47 was the dominating congener, followed by BDE-99, together accounting for 52 ± 21% of ∑12PBDEs, while BDE-209 was only 11 ± 2%. It was found that PBDEs at the 15 sites showed a primary distribution and fractionation pattern. This study produced more than 700 pairs of air samples in gaseous and particulate phases with a wide temperature range of ∼60 °C, providing a good opportunity to investigate gas-particle partitioning for individual PBDE congeners. The results of gas-particle partitioning analysis for PBDEs using both subcooled-liquid-vapor pressure (PL)-based and octanol-air partition coefficient (KOA)-based models indicated that PBDEs in air at all sampling sites had not reached equilibrium because the slope values (mO) in the KOA-based equation and the opposite slope values (mP) in the PL-based equation at all 15 sampling sites were less than 1. It also found that both mO and -mP were significantly and positively correlated with the annual average temperatures of sampling sites and also significantly and negatively correlated with the mole masses of PBDE congeners, indicating a general trend that the higher the temperature at the sampling site and the lower the mole mass of the PBDE congeners are, the closer to the equilibrium the congeners approach and vice versa. To our knowledge, this is the first study to report the correlations of the slope values for both the KOA-based and PL-based equations with temperatures at sampling sites and mole masses for individual PBDE congeners.
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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 | 0.000 | 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 | 0.001 | 0.004 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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; both teacher heads agree on what is shown here.
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".