Using a Time-of-Travel Sampling Approach to Quantify Per- and Polyfluoroalkyl Substances (PFAS) Stream Loading and Source Inputs in a Mixed-Source, Urban Catchment

Probably not a substantial claim: may not pass S2 (checkable).

There is a critical need for catchment-scale PFAS loading data.

“One study went as far as to state that there is a critical need for this type of catchment-scale PFAS loading data.16”

• cites [16] sourceSupported

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

Multivariate analyses have been used to establish PFAS source signatures and distinguish PFAS source inputs in surface water.

“Multivariate analyses have been used to establish PFAS source signatures and distinguish PFAS source inputs in surface water.”

• cites [7] sourceNot checked — no full text of the source
• cites [8] sourceSupported
• cites [9] sourceSupported

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

Tributaries that join Little Neshaminy Creek between sites 11-12 could also be a potential source of PFDA in the system.

“Tributaries that join Little Neshaminy Creek between sites 11-12 could also be a potential source of PFDA in the system, although several studies have observed PFDA in STP outfalls.”

• cites [44] sourceNot checked — no full text of the source
• cites [45] sourceCould not verify

  The Results and discussion section, “PFAS in WWTP matrices” (page unavailable), reports a significant increase in PFDA between influent and final effluent at Australian wastewater treatment plants. It does not address Little Neshaminy Creek, tributaries between sites 11–12, or whether those tributaries could supply PFDA; searches for those locations and for tributary sources found no relevant passage. (LLM, conf=0.78)

  Experimental — accuracy not yet measured
• cites [46] sourceNot checked — no full text of the source

May combine two claims.

Diurnal fluctuations from STPs could account for an estimated 12-30% diurnal variation in PFAS load from PCSTP and an estimated 33-82% variation in load from LCSTP, assuming constant PFAS concentration from the STP.

“Diurnal fluctuations from STPs could account for an estimated 12-30% diurnal variation in PFAS load from PCSTP and an estimated 33-82% variation in load from LCSTP, assuming constant PFAS concentration from the sewage treatment plant (Table S6).”

• AssumptionThe authors state this as an assumption: PFAS concentration from the sewage treatment plant is constant for the diurnal variation estimate.

May combine two claims.

Point discharges from two sewage treatment plants resulted in similar PFCA and PFSA load increases (6 and 10 μg/s respectively) below the first STP and greater PFCA than PFSA load increases (23 and 13 μg/s respectively) below the second STP.

“Point discharges from two sewage treatment plants (STPs) resulted in increases in PFCA and PFSA loads that were similar (6 and 10 μg/s respectively) below the first STP and greater for PFCA compared to PFSA loads (23 and 13 μg/s respectively) below the second STP.”

May combine two claims.

Overall percent increases in total PFAS load ranged from 20 to 277% for military base inputs and 44 to 77% for STP inputs.

“Overall, percent increases in total PFAS load ranged from 20 to 277% for military base inputs and 44 to 77% for STP inputs.”

May combine two claims.

Under November 2021 near-average conditions, percent increases in total PFAS loads between sites 4-5 and 12-13 ranged from 44 to 77% and increases of streamflow ranged from 36 to 83%.

“Under the November 2021 near-average conditions, the relative effects of STP effluent (assumed as a constant input) are shown as percent increases in loads and streamflow between sites 4-5 and 12-13 in Table S7, with increases of total PFAS loads ranging from 44 to 77% and increases of streamflow ranging from 36 to 83%.”

• AssumptionThe authors state this as an assumption: STP effluent is a constant input for the percent increases in loads and streamflow between sites 4-5 and 12-13.

May combine two claims.

Measured streamflow generally increased in the downstream direction throughout the focus reach, reflecting inflows from tributaries, point sources, and groundwater discharge; however, there were two instances of measured streamflow loss between upstream and downstream sites.

“Measured streamflow generally increased in the downstream direction throughout the focus reach, reflecting inflows from tributaries, point sources, and groundwater discharge; however, there were two instances of measured streamflow loss between upstream and downstream sites (Table S1).”

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

Daily fluctuations of about 0.5 ft3/s and 6 to 8 ft3/s are commonly observed at gages below Park Creek Sewage Treatment Plant and Log College Sewage Treatment Plant, respectively.

“Daily fluctuations of about 0.5 ft 3 /s and 6 to 8 ft 3 /s are commonly observed at gages below Park Creek Sewage Treatment Plant (PCSTP) and Log College Sewage Treatment Plant (LCSTP), respectively.”

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

Streamflow losses were measured between site 1 (3.21 ft3/s) and site 2 (3.06 ft3/s) and between site 5 (6.99 ft3/s) and site 6 (6.44 ft3/s).

“Losses were measured between site 1 (3.21 ft 3 /s) and site 2 (3.06 ft 3 /s) and between site 5 (6.99 ft 3 /s) and site 6 (6.44 ft 3 /s) (Figure S2).”

May combine two claims.

Of the 40 target PFAS measured, 13 were detected: seven perfluoroalkyl carboxylates, five perfluoroalkyl sulfonates, and one perfluoroalkyl acid precursor.

“Of the 40 target PFAS measured, 19 13 were detected: seven perfluoroalkyl carboxylates (PFCA), five perfluoroalkyl sulfonates (PFSA), and one perfluoroalkyl acid (PFAA) precursor (Figure 2, Table S1).”

May combine two claims.

Around 70% of the total PFSA load at site 13 was derived from the focus catchment including sites 1 to 12, indicating only 30% of the total PFSA load at site 13 is derived from other sources in the other catchments.

“In contrast, around 70% of the total PFSA load at site 13 was derived from the focus catchment including sites 1 to 12, indicating only 30% of the total PFSA load at site 13 is derived from other sources in the other catchments (Figure 3B).”

May combine two claims.

Input from PCSTP and any other potential unidentified sources between sites 4 and 5 increased PFCA loads by 6.0 μg/s (75%) and PFSA loads by 10 μg/s (76%).

“The input from PCSTP and any other potential, unidentified sources between sites 4 and 5 increased PFCA loads by 6.0 μg/s (75%) and PFSA loads by 10 μg/s (76%) whereas the input from LCSTP and other potential unidentified sources between sites 11 and 12 increased PFCA loads by 23 μg/s (76%) and PFSA loads by only 13 μg/s (27%) (Table 1; Table S7).”

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

Stream samples analyzed for pharmaceutical compounds had 50 of 113 analytes detected at one or more sites.

“Stream samples collected and analyzed for pharmaceutical compounds (to aid in source attribution) had numerous detections, with 50 of 113 analytes detected at one or more sites (Figure S4; Table S1).”

May combine two claims.

Reported monthly average flow from the STP effluents represents 30% and 24% of the measured streamflow downstream of the LCSTP and PCSTP outfalls, respectively, on the day of sampling.

“The reported monthly average flow from the STP effluents represents 30% and 24% of the measured streamflow downstream of the LCSTP and PCSTP outfalls, respectively, on the day of sampling.”

May combine two claims.

Around 40% of the total PFCA load at site 13 was derived from the focus catchment that includes sites 1 through 12, indicating about 60% of the total PFCA load at site 13 is coming from other sources in the other stream catchments that were not specifically targeted.

“Around 40% of the total PFCA load at site 13 was derived from the focus catchment that includes sites 1 through 12, indicating ∼60% of the total PFCA load at site 13 is coming from other sources in the other stream catchments that were not specifically targeted (Figure 3A).”

May combine two claims.

Percent mass increases of 6:2 FTS occurred between sites 4-5, 5-6, and 9-10, all downstream of STP or military base inputs.

“Percent mass increases of 6:2 FTS occurred between sites 4-5, 5-6, and 9-10, all downstream of STP or military base inputs, both of which are recognized potential sources of 6:2 FTS. 32,40”

• cites [32] sourceNot checked — no full text of the source
• cites [40]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

PC2 separated the anthropogenic end of PC1 into two groupings: municipal wastewater indicators (quadrant 4) and a mixture of wastewater, military base sources, and possible industrial sources including a source correlated with the VOC n-pentanal along PC2 (quadrant 3).

“PC2 separated the anthropogenic end of PC1 into two groupings: 1) municipal wastewater indicators (quadrant 4) and 2) a mixture of wastewater, military base sources, and possible industrial sources including a source correlated with the VOC, n-pentanal along PC2 (quadrant 3).”

May combine two claims.

The total PFAS load at site 12 was 118 μg/s and at site 13 was 223 μg/s, representing an approximately 2-fold increase in total PFAS load from the other catchments.

“The total PFAS load at site 12 was 118 μg/s and at site 13 was 223 μg/s, representing an ∼2× increase in total PFAS load from the other catchments, assuming conservative transport and no loss to groundwater/surface water interactions (Figure 2).”

• AssumptionThe authors state this as an assumption: Transport from site 12 to site 13 is conservative and there is no loss to groundwater/surface water interactions.

May combine two claims.

Reported monthly average discharge for November 2021 was 8.51 ft3/s for LCSTP and 1.65 ft3/s for PCSTP.

“Discharged effluent fluxes typically were greater at LCSTP than PCSTP; reported monthly average discharge for November 2021 was 8.51 ft 3 /s for LCSTP and 1.65 ft 3 /s for PCSTP.48”

• cites [48] sourceNot checked — no full text of the source

May combine two claims.

The highest loading variables for PC2 were n-pentanal (-), SUV254 (-), Flr_D:C (-), Gd (+), B (+), and certain PFAS (-), predominately PFSA compounds.

“The highest loading variables for PC2 were n-pentanal (-), SUV254 (-), Flr_D:C (-), Gd (+), B (+), and certain PFAS (-), predominately PFSA compounds.”

May combine two claims.

An increase in flow from site 6 to 7 of 1.5 ft3/s (23%) was measured that was not attributable to any known point sources.

“Supporting this observation, an increase in flow from site 6 to 7 of 1.5 ft 3 /s (23%) (Table 1; Figure S2; Table S7) was measured that was not attributable to any known point sources, indicating a potential contribution of groundwater flow to the stream reach.”

May combine two claims.

Further downstream, LCSTP and other potential sources contributed a similar array of PFAS as PCSTP, except for the absence of 6:2 FTS and including the presence of PFDA.

“Further downstream, LCSTP and other potential sources contributed a similar array of PFAS as PCSTP, except for the absence of 6:2 FTS and including the presence of PFDA.”

May combine two claims.

PC1 alone explained 50% of the variation and was generally separated along a gradient across optical properties from natural organic matter indicators to anthropogenic organic matter indicators and contaminant concentrations.

“PC1 alone explained 50% of the variation and was generally separated along a gradient across optical properties from natural organic matter indicators (left of the axis) to optical properties from anthropogenic organic matter indicators and contaminant concentrations (right of the axis).”

May combine two claims.

Input from LCSTP and other potential unidentified sources between sites 11 and 12 increased PFCA loads by 23 μg/s (76%) and PFSA loads by only 13 μg/s (27%).

“The input from PCSTP and any other potential, unidentified sources between sites 4 and 5 increased PFCA loads by 6.0 μg/s (75%) and PFSA loads by 10 μg/s (76%) whereas the input from LCSTP and other potential unidentified sources between sites 11 and 12 increased PFCA loads by 23 μg/s (76%) and PFSA loads by only 13 μg/s (27%) (Table 1; Table S7).”

May combine two claims.

Measured streamflow on the day of sampling indicates that actual STP effluent flows (estimated by downstream site flow minus upstream site flow) were greater than reported monthly average values, representing closer to 45% (12.9 ft3/s) and 26% (1.85 ft3/s) of streamflow downstream from LCSTP and PCSTP, respectively.

“However, measured streamflow on the day of sampling (Table S1) indicates that the actual STP effluent flows (estimated by the downstream site flow minus the upstream site flow) were greater than reported monthly average values, representing closer to 45% (12.9 ft 3 /s) and 26% (1.85 ft 3 /s) of the streamflow downstream from LCSTP and PCSTP, respectively.”

May combine two claims.

Pharmaceutical loads were variable but reflected two main point sources, with large load increases computed downstream of STP inputs followed by decreases in downstream loads of some compounds.

“Pharmaceutical loads were variable but reflected two main point sources, with large load increases computed downstream of STP inputs followed by decreases in downstream loads of some compounds indicating potential nonconservative transport and/or time-varying composition of effluent.”

May combine two claims.

The first detection of 6:2 fluorotelomer sulfonate occurred downstream from PCSTP, and the first detection of perfluorodecanoate occurred downstream from LCSTP.

“The first detection of two additional PFAS occurred downstream from the STPs: 6:2 fluorotelomer sulfonate (6:2 FTS; possible sources include AFFF and STP effluent) occurred downstream from PCSTP, and perfluorodecanoate (PFDA; long chain PFCA, wetting agent, flame retardant, consumer products like fabrics and cookware) 39 occurred downstream from LCSTP (Figure 2).”

May combine two claims.

Pharmaceutical-compound load increases were up to 2 orders of magnitude higher than PFAS load increases between sampling sites, with load differences most pronounced downstream of LCSTP but also observed downstream of PCSTP.

“Pharmaceutical-compound load increases were up to 2 orders of magnitude higher than PFAS load increases between sampling sites (mass/time), with load differences most pronounced downstream of LCSTP but also observed downstream of PCSTP; direct human use contributes these compounds to wastewater (Figure S4).”

May combine two claims.

Increases in PFAS concentrations occurred between sites 4 and 5, but the largest concentration increases occurred for metformin, fexofenadine, Gd, B, and Zn, consistent with wastewater effluent input.

“Increases in PFAS concentrations occurred between these two sites, but the largest concentration increases occurred for metformin, fexofenadine, Gd, B, and Zn, which are consistent with wastewater effluent input (Table S1).[52][53][54][55]”

• cites [52][53][54][55]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

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

The first two PCs account for 75% of variability in the data set.

“The first two PCs account for 75% of variability in the data set.”

May combine two claims.

PFPeA plotted toward the wastewater grouping and PFNA plotted toward n-pentanal in the PCA.

“Of the PFAS compounds, PFPeA plotted toward the wastewater grouping and PFNA plotted toward the compound n-pentanal.”

The quote only partly states this claim.

Sites 8 and 13 are linked to numerous potential PFAS sources including metal manufacturing and plating, plastics and resins, paints and coatings, and more diffuse STPs in the upstream catchments.

“Sites 8 and 13, though plotting more toward the”

Classified as probably not a substantial claim.

A time-of-travel approach that tracks a parcel of surface water as it moves, sampling and measuring sites directly upstream and downstream of PFAS point sources and tributary inputs, is one technique to quantify chemical loading from sources.

“One technique to quantify chemical loading from sources is to use a time-of-travel approach that tracks a parcel of surface water as it moves, sampling and measuring sites directly upstream and downstream of PFAS point sources and tributary inputs.13”

• cites [13]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

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

Sites were sampled under approximate base-flow conditions (3 days after about 6 mm of precipitation) and near long-term median mean daily streamflow values for those days of the year at nearby streamgages.

“Sites were sampled under approximate base-flow conditions (3 days after ∼6 mm of precipitation) 21 and near long-term median mean daily streamflow values for those days of the year at nearby streamgages.22”

• cites [21]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [22] sourceNot checked — no full text of the source

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

At each sampling location, discrete surface water samples were collected following standard U.S. Geological Survey sampling protocols and utilized a spatially integrated sampling approach (equal width intervals, depth integrated) across the stream channel.

“At each sampling location, discrete surface water samples were collected following standard U.S. Geological Survey (USGS) sampling protocols and utilized a spatially integrated sampling approach (equal width intervals, depth integrated) across the stream channel.24”

• cites [24]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim.

Samples were collected using a time-of-travel approach such that sampling occurred on the day and time when the same parcel of water was computed to reach each site.

“Over a three-day period (November 16-18, 2021), samples were collected using a time-of-travel approach such that sampling occurred on the day/time when the same parcel of water was computed to reach each site.”

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

Time-of-travel approaches allow for estimations of the rate of movement of a contaminant through a river reach, the rate of attenuation of the highest concentration, and the approximate length of time required for a contaminant to pass a point in the river.

“Time-of-travel approaches allow for estimations of the rate of movement of a contaminant through a river reach, the rate of attenuation of the highest concentration, and the approximate length of time required for a contaminant to pass a point in the river.13”

• cites [13]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

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

A replicate PFAS sample was collected for quality control at Site 5.

“A replicate PFAS sample was collected for quality control at Site 5 (SW-16, USGS station no.014648955).”

May combine two claims.

The study catchment contains documented PFAS point sources (military bases with AFFF releases and STP outfalls) and diffuse sources (urban runoff and groundwater with documented PFAS contamination) and consequently PFAS surface and groundwater contamination.

“The catchment contains documented PFAS point sources (military bases with AFFF releases and STP outfalls that discharge to streams) and diffuse sources (urban runoff and groundwater with documented PFAS contamination that discharge to streams) and consequently, PFAS surface and groundwater contamination.4,11,18”

• cites [4] sourceNot checked — no full text of the source
• cites [11] sourceNot checked — no full text of the source
• cites [18] sourceNot checked — no full text of the source

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

Sources of PFAS to surface water include PFAS manufacturing, microchip manufacturing, metal-plating, textile industries, sewage treatment plants, combined sewer overflows, landfills, and aqueous film-forming foam releases.

“Sources of PFAS to surface water include PFAS manufacturing, microchip manufacturing, metal-plating, textile industries, sewage treatment plants (STPs), combined sewer overflows, landfills, and aqueous film-forming foam (AFFF) releases, among others.”

• cites [4] sourceNot checked — no full text of the source
• cites [5] sourceNot checked — no full text of the source
• cites [6] sourceNot checked — no full text of the source

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

Those percent increases may be larger or smaller depending on variable STP discharge.

“Those percent increases may be larger or smaller depending on variable STP discharge.”

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

For PFAS collection, additional steps were added to standard procedures to reduce sample contamination, focused on sampling equipment types, equipment cleaning, and the clean-hands/dirty-hands procedure.

“For PFAS collection, additional steps were added to standard procedures to reduce sample contamination, and these additional steps focused on sampling equipment types, equipment cleaning, and details on the clean-hands/dirty-hands procedure.4”

• cites [4] sourceNot checked — no full text of the source

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

Pumping wells in the vicinity and complex groundwater/surface water interactions in this fractured-rock setting could be contributing to streamflow loss.

“Pumping wells in the vicinity and complex groundwater/surface water interactions in this fractured-rock setting could be contributing to streamflow loss.11”

• cites [11] sourceNot checked — no full text of the source

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

Equipment blanks and field blanks were not part of this synoptic study but were part of a larger Pennsylvania statewide study.

“Equipment blanks and field blanks were not part of this synoptic study but were part of a larger Pennsylvania statewide study and are described by Breitmeyer et al. (2023).4”

• cites Breitmeyer et al. (2023) sourceNot checked — no full text of the source

May combine two claims.

Reports have quantified concentrations of PFCA and PFSA compounds in groundwater at and near the base, and when above background, PFSA compound concentrations, especially PFOS and PFHxS, routinely exceed PFCA (PFOA) concentrations.

“Moreover, reports have also quantified concentrations of PFCA and PFSA compounds in groundwater at and near the base, and when above background, PFSA compound concentrations, especially PFOS and PFHxS, routinely exceed PFCA (PFOA) concentrations.36,37”

• cites [36]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [37]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

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

Daily fluctuations in effluent flows, treatment technologies, and general waste differences by plants could account for the differences in both PFAS and pharmaceutical loading from these plants.

“Daily fluctuations in effluent flows, treatment technologies, and general waste differences by plants could account for the differences in both PFAS (Figure 2) and pharmaceutical (Figure S4) loading from these plants.”

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

Other studies have shown decreases in 6:2 FTS mass in sediment and water from chemical oxidation or biotransformation of 6:2 FTS into terminal PFAS under certain environmental conditions.

“Other studies have shown decreases in 6:2 FTS mass in sediment and water from chemical oxidation or biotransformation of 6:2 FTS into terminal PFAS under certain environmental conditions (presence of ultraviolet light, hydrogen peroxide concentration, and dissolved oxygen concentration).32,41,42”

• cites [32] sourceNot checked — no full text of the source
• cites [41] sourceNot checked — no full text of the source
• cites [42] sourceNot checked — no full text of the source

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

Optical brighteners are fluorescent chemical agents used to whiten and brighten materials, and their removal during STP treatment varies by compound.

“Optical brighteners are fluorescent chemical agents used to whiten and brighten materials, and their removal during STP treatment varies by compound.56,57”

• cites [56] sourceNot checked — no full text of the source
• cites [57] sourceNot checked — no full text of the source

May combine two claims.

Permitted influent for LCSTP included two industrial dischargers: an industrial user in the electronics and manufacturing sector and an industrial user in the food production sector.

“Permitted influent for LCSTP included two industrial dischargers: an industrial user in the electronics and manufacturing sector and an industrial user in the food production sector.”

• cites written communication, December 4, 2023Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Neither PCSTP nor LCSTP accepted any hauled waste.

“Neither PCSTP nor LCSTP accepted any hauled waste.”

• cites written communication, December 4, 2023Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

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

Hamid et al. (2020) indicate that indirect photolysis of 6:2 FTS is a relevant transformation pathway with a 15-day half-life using simulated sunlight in the presence of landfill leachate, suggesting that photolysis is a likely transformation catalyst in sunlit aquatic environments.

“Hamid et al. (2020) 43 indicate that indirect photolysis of 6:2 FTS is a relevant transformation pathway with a 15-day half-life using simulated sunlight in the presence of landfill leachate, suggesting that photolysis is a likely transformation catalyst in sunlit aquatic environments.”

• cites Hamid et al. (2020)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [43] sourceNot checked — no full text of the source

Classified as probably not a substantial claim.

Pharmaceutical compounds fexofenadine and metformin, combined with the elements Zn, Gd, and B, have been used to trace and/or characterize wastewater effluent source inputs.

“The pharmaceutical compounds fexofenadine and metformin, combined with the elements Zn, Gd, and B, have been used to trace and/or characterize wastewater effluent source inputs.5,[52][53][54][55]”

• cites [5] sourceNot checked — no full text of the source
• cites [52]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [53]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

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

Four additional potential sources located near the tributary that enters between sites 9 and 10 could be contributing PFAS loads in addition to military base drainage.

“There are four additional potential sources located near the tributary that enters between sites 9 and 10 (Figure S5) that could be contributing PFAS loads in addition to military base drainage (Figure 2).”

May combine two claims.

For PCSTP, the only permitted waste discharged to streams was from domestic sources, and for LCSTP, the only permitted waste discharged was from domestic sources and the two noted industrial sources.

“Thus, for PCSTP, the only permitted waste that was discharged to streams was from domestic sources, and for LCSTP, the only permitted waste that was discharged was from domestic sources and the two noted industrial sources.”

May combine two claims.

Surface-water PFAS sources from NASJRB Willow Grove and BANG could be from direct runoff, outfall discharge, and/or groundwater discharge.

“Surface-water PFAS sources from NASJRB Willow Grove and BANG could be from direct runoff, outfall discharge, and/or groundwater discharge.”

May combine two claims.

Additional sources, as well as potential atmospheric deposition, may help explain the total PFAS load increase between sites 12 and 13 and suggest that many other potential sources in the catchment could warrant further investigation.

“These additional sources, as well as potential atmospheric deposition, may help explain the total PFAS load increase between sites 12 (118 μg/s) and 13 (223 μg/s) and suggest that while this study focused on a few major inputs, there are many other potential sources in the catchment that could warrant further investigation.”

May combine two claims.

A PCA model used as an exploratory tool discriminates source inputs within the study catchment and provides a second line of evidence corroborating the load analysis.

“A PCA model was used as an exploratory tool to discriminate source inputs within the study catchment and provides a second line of evidence corroborating the load analysis (Figure 4; Table S5).”

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

n-Pentanal is a chemical used in the food additives, packaging, printing, and plastic industries.

“The compound n-pentanal is a chemical used in the food additives, packaging, printing, and plastic industries [60][61][62]”

• cites [60][61][62]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

HMTA likely reflected use in either industrial applications, medicine, or AFFF formulations.

“which likely reflected use in either industrial applications, medicine, or AFFF formulations.65”

• cites [65]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Site 8 plotted in quadrant 1, reflecting a more background-like chemical signature.

“Site 8, which represented the Little Neshaminy drainage upstream from Park Creek, plotted in quadrant 1, reflecting a more”

May combine two claims.

Site 12 is downstream of LCSTP, and thus it is expected that this site would plot in Quadrant 4 with chemical variables indicative of municipal wastewater effluent.

“Site 12 is downstream of LCSTP, and thus it is expected that this site would plot in Quadrant 4 with chemical variables that are indicative of municipal wastewater effluent.[52][53][54][55]58,67,68”

• cites [52][53][54][55]58,67,68Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Although no source inputs were documented between sites 6 and 7, there was a shift between these two sites that suggested potential influence from municipal wastewater.

“Although no source inputs were documented between sites 6 and 7, there was a shift between these two sites that suggested potential influence from municipal wastewater”

Classified as probably not a substantial claim.

The ratio of fluorescence in the Flr_T region (more labile DOM) to the Flr_C region (more humic DOM) has also been widely used to indicate the presence of wastewater in surface waters.

“The ratio of fluorescence in the “Flr_T” region (more labile DOM) to the “Flr_C” region (more humic DOM) has also been widely used to indicate the presence of wastewater in surface waters.58,59”

• cites [58]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [59] sourceNot checked — no full text of the source

May combine two claims.

The shift from site 5 to site 6 resembled the shift between sites 2 and 3, indicative of industrial and potential AFFF sources in the tributaries draining the military base, in particular BANG.

“The shift from site 5 to site 6 resembled the shift between sites 2 and 3, which again is indicative of industrial and potential AFFF sources in the tributaries draining the military base, in particular BANG (Figure 1).”

Classified as probably not a substantial claim.

Sampling locations were chosen to capture loads directly upstream and downstream of source inputs.

“sampling locations were chosen to capture loads directly upstream and downstream of these source inputs.”

May combine two claims.

From sites 10 to 11 there was minimal change suggesting that either new source inputs were limited or were similar in chemical signature.

“From sites 10 to 11 there was minimal change suggesting that either new source inputs were limited or were similar in chemical signature.”

May combine two claims.

In larger catchments with multiple sources, identifying specific source loadings can be more challenging, and inputs such as current and legacy groundwater flux could be missed.

“In larger catchments with multiple sources, identifying specific source loadings can be more challenging, and inputs such as current and legacy groundwater flux could be missed.”

May combine two claims.

This study quantified PFAS loadings from known sources and discriminated sampling sites using time-of-travel sampling, flow-integrated sampling, streamflow measurements, and varied chemical data sets.

“Utilizing a time-of-travel sampling approach, flow-integrated sampling, and streamflow measurements, this study quantified PFAS loadings from known sources and further discriminated sampling sites (i.e., source inputs) using a combination of varied chemical data sets.”