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Cited by 142Per- and polyfluoroalkyl substances researchChemical Analysis and Environmental ImpactFluoride Effects and Removal

Centurial Persistence of Forever Chemicals at Military Fire Training Sites

Open access
Ruyle, Bridger J., Thackray, Colin P., Butt, Craig M., LeBlanc, Denis R., Tokranov, Andrea K., Vecitis, Chad D., Sunderland, Elsie M.·2023·Environmental Science & Technology
DOI 10.1021/acs.est.3c00675PMC PMC10233753
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Abstract

Drinking water contamination by per- and polyfluoroalkyl substances (PFAS) is widespread near more than 300 United States (U.S.) military bases that used aqueous film-forming foams (AFFF) for fire training and firefighting activities. Much of the PFAS at these sites consist of precursors that can transform into terminal compounds of known health concern but are omitted from standard analytical methods. Here, we estimate the expected duration and contribution of precursor biotransformation to groundwater PFAS contamination at an AFFF-contaminated military base on Cape Cod, Massachusetts, United States, by optimizing a geochemical box model using measured PFAS concentrations from a multidecadal time series of groundwater and a soil survey in the source zone. A toolbox of analytical techniques used to reconstruct the mass budget of PFAS showed that precursors accounted for 46 ± 8% of the extractable organofluorine (a proxy for total PFAS) across years. Terminal PFAS still exceed regulatory limits by 2000-fold decades after AFFF use ceased. Measurements and numerical modeling show that sulfonamido precursors are retained in the vadose zone and their slow biotransformation into perfluoroalkyl sulfonates (half-life > 66 yr) sustains groundwater concentrations of perfluorobutane sulfonate (PFBS) and perfluorohexane sulfonate (PFHxS). The estimated PFAS reservoir in the vadose zone and modeled flux into groundwater suggest PFAS contamination above regulatory guidelines will persist for centuries without remediation.

AI snapshot

Written from the paper’s full text.

TL;DR

At a Cape Cod military fire-training site, precursors made up 46 ± 8% of extractable organofluorine and slow biotransformation of vadose-zone sulfonamido precursors sustained groundwater PFBS and PFHxS decades after AFFF use stopped. Model projections indicate groundwater PFAS will remain above Massachusetts regulatory limits for centuries without remediation.

Key findings

  • Precursors accounted for 46 ± 8% of extractable organofluorine across years; the sum of six regulated PFAS averaged less than half (46 ± 13%) of EOF, and precursors with analytical-grade standards added only 5 ± 1%.
  • Groundwater PFAS greatly exceeded guidelines: the sum of six state-regulated PFAS ranged from 4,300 to 74,000 ng L–1, PFOS reached 22,000 ng L–1, and terminal PFAS still exceeded regulatory limits by 2000-fold decades after AFFF use ceased.
  • Slow precursor biotransformation sustained PFBS and PFHxS: estimated half-lives were 340–670 yr (lower bound 66 yr); in 2021, 98% (IQR 92–99%) of C4 PFSA and 56% (IQR 18–88%) of C6 PFSA in groundwater were formed via precursor biotransformation, versus 0.06% for C8 PFSA.
  • Without remediation, groundwater concentrations were not expected to fall below the Massachusetts MCL before the year 2500; in 2021, 57% of PFAS releases remained in the vadose zone, 3% were in groundwater beneath the fire training area, and 40% had migrated downgradient.

Methods

  • Field site: Joint Base Cape Cod fire training area, where 3M AFFF was used routinely in 1970–1985 and once in 1997; vadose zone thickness was approximately 17 m. Groundwater samples came from well S425-0063 between 2007 and 2021 (six time points), plus an Air Force vadose zone soil survey.
  • Four analytical techniques were used: targeted LC-MS/MS for 29 PFAS including 11 precursors; the total oxidizable precursor assay interpreted with Bayesian inference (TOP+BI); extractable organofluorine by combustion ion chromatography; and HRMS suspect screening for 252 PFAS.
  • Four first-order geochemical box models were built for PFOA and for C4/C6/C8 PFSA precursor–terminal pairs, optimized with Bayesian MCMC against groundwater time series and soil survey data, then projected forward 5000 years; site-averaged solid–water (Kd) and air–water interface (Kai) partition coefficients were derived from optimized retardation coefficients.

Limitations

  • The paper states that it did not use a broader spatial domain or traditional spatially resolved groundwater models because many parameters were unknown or too uncertain and such models were computationally expensive; instead it used simpler box models with quantified uncertainty. Soil moisture was not recorded at the site between 2007–2021, so drought index and kettle-lake water altitude were used as proxies. The PFOA model omitted precursor biotransformation, and its optimized Vtraining was somewhat higher than for the PFSA models, possibly reflecting an additional non-3M source or fewer constraints.
  • The paper states that commercial standards are available for <10 of the hundreds of precursors detected in AFFF, and HRMS provides qualitative suspect screening rather than quantitative measurement. Derived Kd and Kai values are site-averaged steady-state estimates; the paper notes that soil-moisture effects could be confirmed with site-specific lysimetric measurements in future work.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1021/acs.est.3c00675

Cites

43 of 43 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 92 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    TOP+BI results suggest that 3M products accounted for 81 ± 5% of the AFFF used at the fire training area.

    “TOP+BI results suggest that 3M products accounted for 81 ± 5% of the AFFF used at the fire training area (Table S19, eqs S4–S5).”
    Quote in the paperSubstantial claim
  • Findingown data

    The abundance of 8:2 FT precursors in 3M AFFF was <8% of PFOA.

    “the abundance of 8:2 FT precursors, which originate from other AFFF products, was <8% of PFOA (Table S6).”
    Quote in the paperSubstantial claim
  • Findingown data

    The sum of six state-regulated PFAS in samples from well S425-0063 directly below the fire training area ranged between 4300 and 74,000 ng L-1.

    “The sum of the six state-regulated PFAS (PFOS/C8 perfluoroalkyl sulfonate: PFSA, PFOA/C7 perfluoroalkyl carboxylate: PFCA, PFHxS/C6 PFSA, and the C6, C8, and C9 PFCA) in samples from well S425-0063 directly below the fire training area ranged between 4300–74,000 ng L–1 (Figure 1c, Table S5).”
    Quote in the paperSubstantial claim
  • Findingown data

    Almost all (14/15) identified precursors were perfluoroalkyl sulfonamido compounds previously identified in 3M AFFF or suspected metabolites.

    “Almost all (14/15) were perfluoroalkyl sulfonamido compounds previously identified in 3M AFFF or suspected metabolites.7,8”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [7] source

      Not checked in the free run.

    • cites [8] source

      Not checked in the free run.

  • Findingnone given

    The linear groundwater velocity at the JBCC fire training area is 0.4 m day-1.

    “The linear groundwater velocity is 0.4 m day–1.”
    Quote in the paperSubstantial claim
  • May combine two claims. 39
  • Classified as probably not a substantial claim. 11

  • May combine two claims.

    Findingnone given

    Soil and sediment at the JBCC fire training area consist of quartz and feldspar sand with <0.1% organic carbon and a porosity of 0.39.

    “Soil and sediment consist of quartz and feldspar sand with <0.1% organic carbon and a porosity of 0.39 (Figures S1–S3).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    Increasing DSCI indicative of the onset of drought-like conditions (DSCI > 0) began in May 2021 and continued to rise until moderate drought conditions at the sampling date in July 2021 (DSCI = 123), the date when the lowest PFAS concentrations in groundwater were observed.

    “Increasing DSCI indicative of the onset of drought-like conditions (DSCI > 0) began in May 2021 and continued to rise until they reflected moderate drought conditions at the sampling date in July 2021 (DSCI = 123),35 the date when the lowest PFAS concentrations in groundwater were observed (Figures 2 and S8).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [35] National Drought Mitigation Center, University of Nebraska-Lincoln. North American Drought Monitor . https://droughtmonitor.unl.edu/NADM/Home.aspx (accessed Feb 11, 2022).

      Not checked in the free run.

  • May combine two claims.

    Findingown data

    In JBCC groundwater, temporal fluctuations in PFAS concentrations of up to an order of magnitude occurred between 2007-2021, but no consistent trends were observed for EOF, terminal PFAS, or precursors.

    “In JBCC groundwater, temporal fluctuations in PFAS concentrations of up to an order of magnitude occurred between 2007–2021, but no consistent trends were observed for EOF, terminal PFAS, or precursors (Figure 2a, Figure S8, Table S5).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    The Vtraining for PFOA in the optimized model was somewhat higher than for the three PFSA, which were in good agreement (overlapping IQR).

    “The Vtraining for PFOA in the optimized model was somewhat higher than for the three PFSA, which were in good agreement (overlapping IQR).”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Findingnone given

    The annual average recharge from precipitation at the JBCC fire training area is 0.73 m.

    “The annual average recharge from precipitation is 0.73 m.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    DSCI increased from 13 to 64 between June and July 2014 and indicated abnormally dry conditions when 16-44% declines in terminal PFAS between months were observed.

    “DSCI increased from 13 to 64 between June and July 2014 and indicated abnormally dry conditions when we observed 16–44% declines in terminal PFAS between months (Table S20).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    Together with their terminal PFSA, the C4, C6, and C8 precursor groups make up 88 ± 1% of total PFAS in 3M AFFF and 40 ± 8% of total PFAS in groundwater beneath the JBCC fire training area.

    “Together with their terminal PFSA, these three precursor groups make up 88 ± 1% of total PFAS in 3M AFFF and 40 ± 8% of total PFAS in groundwater beneath the JBCC fire training area.11”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [11] source

      Not checked in the free run.

  • May combine two claims.

    Findingown data

    Highest PFAS concentrations occurred in both the earliest (2007) and more recent (2020) samples, while lowest concentrations were detected in 2021.

    “Highest PFAS concentrations occurred in both the earliest (2007) and more recent (2020) samples, while lowest concentrations were detected in 2021 (see SI Results and Discussion).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Statistically significant correlations were found between groundwater PFAS concentrations and the water altitude of the kettle lake for PFOA and PFBS but not for PFHxS, PFOS, or precursors.

    “We found statistically significant correlations between groundwater PFAS concentrations and the water altitude of the kettle lake for PFOA (C7 PFCA) and PFBS (C4 PFSA) but not for PFHxS (C6 PFSA), PFOS (C8 PFSA), or precursors.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    PFOS and the C6/C8 PFSA precursors have higher Kai and higher Kd compared to PFOA.

    “By contrast, PFOS and the C6/C8 PFSA precursors have higher Kai (are more surface active) and higher Kd (are more sorptive to solids) compared to PFOA (Figure 4).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    PFHxS was the most abundant terminal PFAS in every sample collected as part of this study and PFBS was detectable in all samples.

    “Instead, PFHxS was the most abundant terminal PFAS in every sample collected as part of this study and PFBS was detectable in all samples (Table S5).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Most of these microcosm studies observe rapid metabolism into other stable precursor intermediates such as the perfluoroalkyl sulfonamides, consistent with high concentrations of these compounds in groundwater at JBCC.

    “Instead, most of these studies observe rapid metabolism into other stable precursor intermediates such as the perfluoroalkyl sulfonamides, consistent with high concentrations of these compounds in groundwater at JBCC (Table S5).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In 2021, 98% (IQR 92-99%) of the C4 PFSA and 56% (IQR 18-88%) of the C6 PFSA in groundwater were formed through precursor biotransformation, whereas C8 precursors only contributed 0.06% (IQR 0.01-0.2%) to the terminal C8 PFSA.

    “In 2021, 98% (interquartile range IQR: 92–99%) of the C4 PFSA and 56% (IQR: 18–88%) of the C6 PFSA in groundwater were formed through precursor biotransformation, whereas C8 precursors only contributed 0.06% (IQR: 0.01–0.2%) to the terminal C8 PFSA.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The biogeochemical box model represents the dominant PFAS mass transfer processes at the fire training area.

  • May combine two claims.

    Findingown data

    In 2021, 57% (IQR = 57-70%) of PFAS releases remained in the vadose zone, 3% (IQR = 2-5%) were in groundwater beneath the fire training area, and 40% (IQR = 25-41%) had migrated to downgradient groundwater and surface waters.

    “Simulated temporal changes in the PFAS reservoir indicated that in 2021, 57% (IQR = 57–70%) of PFAS releases remained in the vadose zone, 3% (IQR = 2–5%) were in groundwater beneath the fire training area, and 40% (IQR = 25–41%) had migrated to downgradient groundwater and surface waters.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The biogeochemical box model represents the dominant PFAS mass transfer processes at the fire training area.

  • May combine two claims.

    Premisecitation

    TOP+BI can reproduce EOF measurements in AFFF, confirming that it quantitatively captures all PFAS derived from AFFF use.

    “TOP+BI can reproduce extractable organofluorine measurements (EOF) in AFFF, thereby confirming that it quantitatively captures all PFAS derived from AFFF use.6”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [6] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Past work showed that EOF concentrations provide a good proxy for total PFAS in AFFF and range between (850-900) ×10^6 nM F in the 3M product.

    “Past work showed that EOF concentrations provide a good proxy for total PFAS in AFFF and range between (850–900) ×106 nM F in the 3M product.6”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [6] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    The higher Vtraining for PFOA may reflect an additional (non-3M AFFF) source at the site or fewer constraints in the PFOA model relative to the PFSA because it does not include precursor biotransformation.

    “This may reflect an additional (non-3M AFFF) source at the site or fewer constraints in the PFOA model relative to the PFSA because it does not include precursor biotransformation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Perfluoroalkyl sulfonamido compounds (C4, C6, and C8) are the predominant precursors in 3M AFFF (46 ± 1% of total PFAS) and are biotransformed in the subsurface into PFSA of the same number of perfluorinated carbons.

    “Perfluoroalkyl sulfonamido compounds (C4, C6, and C8) are the predominant precursors in 3M AFFF (46 ± 1% of total PFAS) and are biotransformed in the subsurface into PFSA of the same number of perfluorinated carbons.11,24”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [11] source

      Not checked in the free run.

    • cites [24] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Results of this work suggest that variability in groundwater PFAS concentrations reflects site-specific hydrologic conditions and that increasing vadose zone saturation results in greater concentrations of PFAS in groundwater.

    “Results of this work suggest that variability in groundwater PFAS concentrations reflects site-specific hydrologic conditions and that increasing vadose zone saturation results in greater concentrations of PFAS in groundwater.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    None of the detected perfluoroalkyl sulfonamido precursors are included in current U.S. EPA methods and only one (perfluorooctane sulfonamide) is included in a new draft method.

    “None of the detected perfluoroalkyl sulfonamido precursors are included in current U.S. EPA methods and only one (perfluorooctane sulfonamide) is included in a new draft method.29−31”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [29] Shoemaker, J. A.; Tettenhorst, D. R. Method 537.1 Determination of Selected Per- and Polyfluorinated Alkyl Substances in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS), 2018. https://cfpub.epa.gov/si/si_public_record_Report.cfm?dirEntryId=343042&Lab=NERL (accessed April 19, 2022).

      Not checked in the free run.

    • cites [30] Rosenblum, L.; Wendelken, S. C. Method 533: Determination of Per- and Polyfluoroalkyl Substances in Drinking Water by Isotope Dilution Anion Exchange Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry, 2019. https://www.epa.gov/sites/default/files/2019-12/documents/method-533-815b19020.pdf (accessed April 19, 2022).

      Not checked in the free run.

    • cites [31] Hanley, A. Draft Method 1633 Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS, 2021. https://www.epa.gov/system/files/documents/2021-09/method_1633_draft_aug-2021.pdf (accessed May 04, 2022).

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Theoretical simulations have identified variability in the air-water interface and associated partitioning of PFAS as the strongest controls on PFAS transport in the subsurface, but time series data to confirm this at field sites are lacking.

    “Theoretical simulations have identified variability in the air–water interface and associated partitioning of PFAS as the strongest controls on PFAS transport in the subsurface, but time series data to confirm this at field sites are lacking.33,34”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [33] source

      Not checked in the free run.

    • cites [34] source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Prior field studies and theoretical models suggest that retention of PFAS in the vadose zone due to partitioning at the air-water interface and biotransformation of precursors may sustain long-term downstream contamination of the more mobile perfluoroalkyl sulfonates and perfluoroalkyl carboxylates.

    “These studies suggest that retention of PFAS in the vadose zone due to partitioning at the air–water interface and biotransformation of precursors may sustain long-term downstream contamination of the more mobile perfluoroalkyl sulfonates (PFSA) and PFCA.”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [5] source

      Not checked in the free run.

    • cites [12] source

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    • cites [13] source

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    • cites [14] source

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  • May combine two claims.

    Premisenone given

    Prior results are either theoretical or only include site measurements from a single snapshot in time.

    “However, prior results are either theoretical or only include site measurements from a single snapshot in time.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Past work indicates the water altitude of the kettle lake is controlled by the position of the water table, which itself reflects recent precipitation and high soil moisture conditions on timescales of weeks to months.

    “Past work indicates the water altitude of the kettle lake is controlled by the position of the water table, which itself reflects recent precipitation and high soil moisture conditions on timescales of weeks to months.15,18”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [15] LeBlanc, D. R.; Guswa, J. H.; Frimpter, M. H.; Londquist, C. J. Ground-Water Resources of Cape Cod, Massachusetts; Hydrologic Atlas; USGS Numbered Series 692 ; United States Geological Survey, 1986.

      Not checked in the free run.

    • cites [18] Massey, A. J.; Carlson, C. S.; LeBlanc, D. R. Ground-Water Levels near the Top of the Water-Table Mound, Western Cape Cod, Massachusetts, 2002-04; Scientific Investigations Report; Scientific Investigations Report 2006–5054 ; U.S. Geological Survey: Reston, Virginia, 2006; p 14. https://pubs.er.usgs.gov/publication/sir20065054 (accessed April 19, 2022). source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Precipitation leads to higher soil moisture content, which results in collapse of the air-water interface at saturation, promotes migration of surface active PFAS into the aqueous phase, and increases aquifer recharge.

    “Precipitation leads to higher soil moisture content, which results in collapse of the air–water interface at saturation, promotes migration of surface active PFAS into the aqueous phase, and increases aquifer recharge.25,34”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [25] source

      Not checked in the free run.

    • cites [34] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Biotransformation of 8:2 FT precursors produces PFOA and other PFCA.

    “Biotransformation of 8:2 FT precursors produces PFOA and other PFCA.24”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [24] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    3M AFFF was used routinely at the JBCC fire training area between 1970 and 1985 and for firefighting once in 1997.

    “3M AFFF was used routinely at this site for fire training between 1970 and 1985 and for firefighting once in 1997.12”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [12] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    PFOA is present in 3M AFFF but is not a major biotransformation endpoint for sulfonamido precursors.

    “The other major terminal PFAS in groundwater was PFOA (C7 PFCA; 17 ± 8% of total PFAS), which is present in 3M AFFF but is not a major biotransformation endpoint for sulfonamido precursors.5,6,24”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [5] source

      Not checked in the free run.

    • cites [6] source

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    • cites [24] source

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  • May combine two claims.

    Interpretationcitation

    Since ΔG is primarily driven by hydrophobicity, the lower polarizability of perfluorinated carbons compared to hydrocarbons limits their interactions with water and results in large differences in environmental behavior among homologous PFAS.

    “Since ΔG is primarily driven by hydrophobicity, the lower polarizability of perfluorinated carbons compared to hydrocarbons limits their interactions with water and results in large differences in environmental behavior among homologous PFAS (such as the differing relationship among PFSA with the soil moisture proxy in Figure 3).44”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [44] Schwarzenbach R. P., 2017

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    PFOS and C6/C8 PFSA precursors can outcompete PFOA for limited sites at the air-water interface under higher soil moisture content conditions and will be preferentially retained on solid surfaces instead of migrating into groundwater, explaining the lack of clear trends with the soil moisture proxy.

    “This means they can outcompete PFOA for limited sites at the air–water interface under higher soil moisture content conditions and will be preferentially retained on solid surfaces instead of migrating into groundwater, explaining the lack of clear trends with the soil moisture proxy in this work.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Larger Kd and Kai of precursors result in lower mobility of precursors compared to their terminal PFSA and greater retention in the source zone.

    “In summary, the larger Kd and Kai of precursors result in lower mobility of precursors compared to their terminal PFSA and greater retention in the source zone.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Slow precursor biotransformation (expected half-lives = 340-670 yr; lower bound = 66 yr) indicates that some precursors persist and are transported to downstream environments where potential human and wildlife exposures occur.

    “Slow precursor biotransformation (expected half-lives = 340-670 yr; lower bound = 66 yr), indicates that some precursors persist and are transported to downstream environments where potential human and wildlife exposures occur.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    Kai is larger for precursors than the PFSA because their nonfluorinated substituents are bulkier and less hydrated than sulfonates, which enables a closer approach to the air-water interface.

    “Kai is larger for precursors than the PFSA because their nonfluorinated substituents are bulkier and less hydrated than sulfonates which enables a closer approach to the air–water interface.42”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [42] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    PFBS and PFHxS are less surface active and therefore less sensitive to the collapse of the air-water interface.

    “This means they are less surface active and therefore less sensitive to the collapse of the air–water interface.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    These results are consistent with significantly greater partition coefficients for precursors compared to PFSA, leading to greater retention of precursors in the vadose zone, and/or production of PFSA through precursor biotransformation.

    “These results are consistent with significantly greater partition coefficients for precursors compared to PFSA, leading to greater retention of precursors in the vadose zone, and/or production of PFSA through precursor biotransformation (Figure 4).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Concentration dependency of these coefficients has been observed in prior experimental work but has been shown to have minimal impact on long-term environmental behavior.

    “Concentration dependency of these coefficients has been observed in prior experimental work but has been shown to have minimal impact on long-term environmental behavior.33”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [33] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S1 (asserted).

    Interpretationreasoning

    The persistence of PFBS and PFHxS in groundwater is controlled by slow biotransformation of their precursors.

    “We therefore hypothesized that the persistence of PFBS and PFHxS in groundwater is controlled by slow biotransformation of their precursors.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning

    PFBS and PFHxS should have significantly declined in the decades after active AFFF use and exhibited minimal abundance in groundwater during the sampling period 2007-2021.

    “This result suggests PFBS and PFHxS should have: (a) significantly declined in the decades after active AFFF use, and (b) exhibited minimal abundance in groundwater during the sampling period for this study between 2007–2021.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    The combined role of Kd and Kai in producing the observed field trends is consistent with previous theoretical models that find competition at the air-water interface and greater sorption of PFOS leads to its extended retardation in the vadose zone compared to PFOA.

    “The combined role of Kd and Kai in producing the observed field trends is consistent with previous theoretical models that find competition at the air–water interface and greater sorption of PFOS leads to its extended retardation in the vadose zone compared to PFOA.40,41”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [40] source

      Not checked in the free run.

    • cites [41] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    PFOS is absent from contemporary foams and its production was phased out by 3M around 2002, indicating residual contamination is a legacy problem.

    “PFOS is absent from contemporary foams and its production was phased out by 3M (the main global manufacturer) around 2002, indicating residual contamination is a legacy problem.5,6,8”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [5] source

      Not checked in the free run.

    • cites [6] source

      Not checked in the free run.

    • cites [8] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Sulfonamido precursors are present in remote environments, strongly bioaccumulate, and are increasingly accumulating in wildlife.

    “Sulfonamido precursors are present in remote environments, strongly bioaccumulate, and are increasingly accumulating in wildlife.51−53”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [51] source

      Not checked in the free run.

    • cites [52] source

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    • cites [53] source

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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Since chemical transport is comparatively rapid on Cape Cod, other AFFF sites may experience even longer periods of elevated PFAS exposures.

    “Since chemical transport is comparatively rapid on Cape Cod, other AFFF sites may experience even longer periods of elevated PFAS exposures.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Chemical transport is comparatively rapid on Cape Cod.

  • May combine two claims.

    Premisecitation

    The U.S. EPA monitors drinking water for emerging contaminants under the Unregulated Contaminants Monitoring Rule (UCMR) but did not include any precursors in their first PFAS survey (UCMR 3 2012) and plans to include only six precursors (only 1 of the 15 identified in this work) in their second upcoming survey (UCMR 5, slated for 2023-2025).

    “The U.S. EPA monitors drinking water for emerging contaminants under the Unregulated Contaminants Monitoring Rule (UCMR) but did not include any precursors in their first PFAS survey (UCMR 3 2012) and plans to include only six precursors (only 1 of the 15 identified in this work) in their second upcoming survey (UCMR 5, slated for 2023-2025).55”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [55] United States Environmental Protection Agency. 86 FR 13846: Revisions to the Unregulated Contaminant Monitoring Rule (UCMR 5) for Public Water Systems and Announcement of Public Meeting ; 2021; Vol. 13846, pp 13846–13872.

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Interpretationnone given

    Results presented here provide the first estimates of bulk precursor physicochemical properties that can be used in the future to parameterize fate and transport models to better predict risks of harmful PFAS exposures.

    “Results presented here provide the first estimates of bulk precursor physicochemical properties that can be used in the future to parameterize fate and transport models to better predict risks of harmful PFAS exposures.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    This work highlights the importance of unregulated and often overlooked precursors for total PFAS exposures near AFFF releases and their role in sustaining high concentrations of regulated terminal PFSA, especially PFBS and PFHxS.

    “This work highlights the importance of unregulated and often overlooked precursors for total PFAS exposures near AFFF releases and their role in sustaining high concentrations of regulated terminal PFSA, especially PFBS and PFHxS.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Little is known about population-wide exposures to precursors.
45 of 45

  • The paper relies on this without support.

    Most precursors are not routinely monitored, and all are currently unregulated.

    “However, most precursors are not routinely monitored, and all are currently unregulated.”

  • The paper relies on this without support.

    Basic data on the physicochemical properties of precursors in 3M AFFF are lacking because analytical standards for precursors are lacking and diverse structures occur at low concentrations at AFFF-impacted sites.

    “The lack of analytical standards for precursors and low concentrations of diverse structures at AFFF-impacted sites has meant basic data on the physicochemical properties of precursors in 3M AFFF are lacking.”

  • The paper relies on this without support.

    Little is known about population-wide exposures to precursors.

    “Little is known about population-wide exposures to precursors.”

  • The paper relies on this without support.

    Chemical transport is comparatively rapid on Cape Cod.

    “Since chemical transport is comparatively rapid on Cape Cod, other AFFF sites may experience even longer periods of elevated PFAS exposures.”

  • The authors state this as an assumption.

    The biogeochemical box model represents the dominant PFAS mass transfer processes at the fire training area.

    “Reservoirs and mass transfer processes represented by the biogeochemical box model of the fire training area (eqs 1–5).”
5 of 5

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • The monitoring well has two different short names

    Minor

    The methods give the well's short name as S25-0063, but the results identify the well as S425-0063. The two identifiers differ by a digit.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 3

  1. Schwarzenbach R. P., 2017, Environmental Organic Chemistry
  2. Darwin R., 2004, Estimated Quantities of Aqueous Film Forming Foam (AFFF) in the United States
  3. United States Environmental Protection Agency. 86 FR 13846: Revisions to the Unregulated Contaminant Monitoring Rule (UCMR 5) for Public Water Systems and Announcement of Public Meeting ; 2021; Vol. 13846, pp 13846–13872.

Cited by

Sorted by citations

Authors
Ruyle, B. J., Thackray, C. P., Butt, C. M., LeBlanc, D. R., Tokranov, A. K., Vecitis, C. D., & Sunderland, E. M.
Affiliations
  • Harvard University (US)
  • SCIEX, Framingham, Massachusetts 01701, United States
  • New England Water Science Center (US)
Corresponding author
Ruyle, Bridger J.
ORCID
Venue
Environmental Science & Technology
Publisher
American Chemical Society (ACS)
Published
2023-05-15
Volume
57
Issue
21
Pages
8096-8106
ISSN
  • 0013-936X (ISSN-L)
  • 1520-5851
DOI
10.1021/acs.est.3c00675
PMC
PMC10233753
OpenAlex
W4376630022
Semantic Scholar
0a4b7f344ac7642436066b6f68a94058875c8155
Cited by
142
References
43
Citations by year
2026: 53 · 2025: 50 · 2024: 35 · 2023: 4
FWCI
12.24
Type
journal article
Language
en
Open access
Licence
Locations
  • Environmental Science & Technology (publishedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
Funders
  • National Institute of Environmental Health Sciences (P4ES027706)
  • U.S. Department of Defense (SERDP ER18-1280)
  • U.S. Geological Survey
Topics
  • Physical Sciences › Environmental Science › Environmental Chemistry › Per- and polyfluoroalkyl substances research
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Chemical Analysis and Environmental Impact
  • Physical Sciences › Environmental Science › Water Science and Technology › Fluoride Effects and Removal
Keywords
PFAS, per- and polyfluoroalkyl substances, aqueous film-forming foam, groundwater contamination, PFAS precursors, biotransformation, perfluoroalkyl sulfonates, PFBS, PFHxS, mass budget, source zone, long-term persistence, Cape Cod
MeSH terms
Alkanesulfonates, Fluorocarbons, Humans, Military Personnel, Water, Water Pollutants, Chemical, Water Pollution, Groundwater

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-06.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-06.

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