Certain Perfluoroalkyl and Polyfluoroalkyl Substances Associated with Aqueous Film Forming Foam Are Widespread in Canadian Surface Waters
Bibliographic record
Abstract
The presence of perfluoroalkyl and polyfluoroalkyl substances (PFASs) commonly associated with aqueous film forming foams (AFFFs) at sites without known AFFF contamination is a largely unexplored area, which may reveal widespread environmental contaminants requiring further investigation. Sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) screening for 23 classes of PFASs, followed by quantitative analysis was used to investigate surface waters from rural, urban, and AFFF-impacted sites in Canada. The PFASs detected included perfluorohexane sulfonamide (FHxSA), 6:2 fluorotelomer sulfonamide (FTSAm), fluorotelomer sulfonamide alkylbetaines (FTABs), fluorotelomer betaines (FTBs), 6:2 fluorotelomer mercaptoalkylamido sulfonate sulfone (FTSAS-SO 2 ), 6:2 fluorotelomerthiohydroxyl ammonium sulfoxide (FTSHA-SO), 6:2 fluorotelomer sulfonamide alkylamine (FTAA) and C3 to C6 perfluoroalkane sulfonamido amphoterics. Detection of FHxSA in all urban and AFFF-impacted sites (0.04–19 ng/L) indicates the widespread presence of rarely considered perfluorohexanesulfonate (PFHxS) precursors in Canadian waters. FTABs and FTBs were especially abundant with up to 16–33 ng/L of 6:2 FTAB in urban and AFFF-impacted water suggesting it may have additional applications, while FTBs were only in AFFF-impacted sites (qualitative; ∑FTBs 80 ng/L). The distributions of PFASs moving downstream along the AFFF-impacted Welland River and between water and sediment suggested differences in the persistence of various AFFF components and enhanced sorption of long-chain fluorotelomer betaines. Total organofluorine combustion-ion chromatography (TOF-CIC) revealed that fluorotelomer betaines were a substantial portion of the organofluorine in some waters and 36–99.7% of the total organofluorine was not measured in the targeted analysis.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".