Organic fluorine content in aqueous film forming foams (AFFFs) and biodegradation of the foam component 6 : 2 fluorotelomermercaptoalkylamido sulfonate (6 : 2 FTSAS)
Bibliographic record
Abstract
Environmental context Total organofluorine and known fluorosurfactants were quantified in 11 aqueous film forming foams (AFFFs) used to extinguish fires in Ontario, Canada, and one commercial AFFF product. By comparing the concentrations of known fluorosurfactants with the total organofluorine, less than 10% of the fluorosurfactants were identified in half of the samples. Our biodegradation experiment with one of the fluorosurfactants using waste-water treatment plant sludge showed that it was a potential source of perfluoroalkyl carboxylates, which are persistent in the environment. Abstract Eleven aqueous film forming foam (AFFF) samples that were used to extinguish fires in Ontario, Canada, and one commercial product, were analysed using a variety of analytical techniques to obtain structural information and quantities of organofluorine and known perfluoroalkyl and polyfluoroalkyl substances (PFASs). The NMR spectra of the foams distinguished the fluorosurfactants that were synthesised by either electrochemical fluorination or telomerisation. Total organofluorine content was quantified using total organofluorine–combustion ion chromatography (TOF-CIC), which revealed that the samples contained from 475 to 18 000µgFmL–1. The common AFFF component 6 : 2 fluorotelomermercaptoalkylamido sulfonate (FTSAS) was quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS) together with perfluoroalkane sulfonates (PFSAs), perfluoroalkyl carboxylates (PFCAs) and fluorotelomer sulfonates (FTSAs); in five samples, 6 : 2 FTSAS was present in concentrations greater than 1000µgmL–1. By comparing the concentrations of these quantifiable fluorochemicals with the total organofluorine content, it was evident that in half of the AFFF samples, less than 10% of the fluorochemicals were identified; in two of the samples, perfluorooctane sulfonate (PFOS) accounted for ~50% of the total organofluorine content. Our degradation experiment with 6 : 2 FTSAS using waste-water treatment plant sludge showed that 6 : 2 FTSAS was a potential source of FTSAs, fluorotelomer alcohols and PFCAs in the environment.
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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 | 0.000 | 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) | 0.001 | 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".