Heterogeneous Photooxidation of Fluorotelomer Alcohols: A New Source of Aerosol-Phase Perfluorinated Carboxylic Acids
Bibliographic record
Abstract
Little is known of the atmospheric fate(s) of fluorotelomer alcohols (FTOHs), a class of high-production-volume chemicals used in the production of water- and oil-repelling surface coatings and which have been detected in a wide variety of urban and remote environmental matrices. In the present study, we investigated the uptake and photochemistry of FTOHs at the surface of TiO2, Fe2O3, Mauritanian sand, and Icelandic volcanic ash. Gas-phase 3,3,3-trifluoropropanol, 4:2 FTOH, and 6:2 FTOH exhibited significant uptake to each of the surfaces under study. The sand- and ash-catalyzed heterogeneous photooxidation of 6:2 FTOH resulted in the rapid production and subsequent slow degradation of surface-sorbed perfluorinated carboxylic acids (PFCAs). We suggest that this transformation, which proceeds via saturated and unsaturated fluorotelomer carboxylic acid intermediates (6:2 FTCA/FTUCA), is catalyzed by Fe and Ti contained within the samples. These results provide the first evidence that the heterogeneous oxidation of FTOHs at metal-rich atmospheric surfaces may provide a significant loss mechanism for these chemicals and also act as a source of aerosol-phase PFCAs close to source regions. Subsequent long-range transport of these aerosol-sorbed PFCAs has the potential to join oceanic transport and local gas-phase FTOH oxidation as a source of PFCAs to Arctic regions.
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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 | 0.002 |
| Science and technology studies | 0.000 | 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) | 0.010 | 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; a candidate call from one teacher head, 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".