Cited by 224Per- and polyfluoroalkyl substances researchGroundwater flow and contamination studiesSoil and Unsaturated Flow

The DOI matches its Crossref record; 56 of the 75 references it cites were found in a registry or an index, and 19 are not checked yet; none of the 39 sources its claims cite is checked for support yet.

A Mathematical Model for the Release, Transport, and Retention of Per‐ and Polyfluoroalkyl Substances (PFAS) in the Vadose Zone

Open access
Guo, Bo, Zeng, Jicai, Brusseau, Mark L.·2020·Water Resources Research

Abstract

Per‐ and polyfluoroalkyl substances (PFAS) are emerging contaminants of critical concern. As surfactants, PFAS tend to accumulate at air‐water interfaces and may stay in the vadose zone for long times before contaminating groundwater. Yet not well understood, the extent of retention in the vadose zone has critical implications for risk management and remediation strategies. We present the first mathematical model that accounts for surfactant‐induced flow and solid‐phase and air‐water interfacial adsorption. We apply the model to simulate PFOS (a PFAS compound of primary concern) transport in the vadose zone at a model fire‐training area site impacted by aqueous film‐forming foam (AFFF). Air‐water interfacial adsorption is shown to have a significant impact—amplified by the low water content due to gravity drainage—total retardation factors range from 233 to 1,355 for the sand and 146 to 792 for the soil used in the study. The simulations illustrate it can take several decades or longer for PFOS to reach groundwater. Counterintuitively, the lower water content in the sand—due to stronger drainage and weaker capillary retention—leads to retardation factors greater than for the soil. Also, most PFOS is adsorbed at air‐water interfaces with only 1–2% in the aqueous phase. The implications include (1) fine‐texture materials could have lower retardation factors than sand due to higher retained water content, (2) soil PFAS concentrations are likely to be orders of magnitude higher than those in groundwater at source zones. Both implications are consistent with recent field observations at hundreds of AFFF‐impacted sites.

Checked 2026-10-06 · 19 references not checked yet

Overview

Integrity signals

Registry

Crossref · 10.1029/2019wr026667

Cites

56 of 75 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 39 cited sources checked · 0 supported · 0 flagged

Show all 88 claims

  • It may state two separate claims as one. 34
  • Probably not a substantial claim. 9
  • The quote only partly states this claim. 1
41 of 41
  • The authors state this as an assumption.

    Capillary pressure head scales with surface tension according to Leverett scaling.

    “Here we assume that the capillary pressure head (−h) scales with surface tension σ following Leverett et al. (1941) and Smith and Gillham (1994)”
  • The authors state this as an assumption.

    The contact angle does not change when PFAS is dissolved.

    “For simplicity, the contact angle is assumed unchanged with dissolved PFAS.”
  • The authors state this as an assumption.

    All precipitation is treated as rainfall, with no distinction between rain and snow.

    “For simplicity, we treat all precipitation as rainfall and do not distinguish between rain and snow in our simulations.”
  • The authors state this as an assumption.

    Evapotranspiration data are approximated as potential evapotranspiration to determine surface evaporation fluxes.

    “In addition, we approximate the evapotranspiration data as potential evapotranspiration to determine the surface evaporation fluxes.”
  • The authors state this as an assumption.

    All applied AFFF solution infiltrates into the vadose zone.

    “Assuming all of the AFFF solutions infiltrate into the vadose zone, it gives a total infiltration of 0.0458cm per training session.”
  • The paper relies on this without support.

    The time scale over which PFAS may remain in the vadose zone due to fluid-fluid interfacial adsorption and the potential for long-term release to groundwater are unknown.

    “In particular, the time scale that PFAS may stay in the vadose zone due to fluid-fluid interfacial adsorption and the potential long-term release to groundwater are unknown.”
  • The paper relies on this without support.

    PFAS behave as surfactants and tend to accumulate at air-water interfaces, potentially remaining in the vadose zone for long periods.

    “when released to the environment they tend to accumulate at air-water interfaces and may stay in the vadose zone for long periods of time (Fig. 1(b,c)).”
  • The paper relies on this without support.

    The implications are consistent with recent field observations at hundreds of AFFF-impacted sites.

    “Both implications are consistent with recent field observations at hundreds of AFFF-impacted sites.”
  • The paper relies on this without support.

    Laboratory-measured parameters used in the simulations are representative of field-scale vadose zone conditions.

    “though our simulations used laboratory measured parameters”
9 of 9

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.

  • First-model claim conflicts with the paper's account of earlier work

    Minor

    The abstract calls this the first model to include surfactant-induced flow and both adsorption processes. The introduction describes an earlier model that included those same processes, although it treated the adsorption coefficients as constant during each simulation.

1 of 1

Citations

Cites

Flagged first, then by citations

Show all 74 references

Research works printed but not linked: 2

  1. 10.1021/es981355 · DOI
  2. Simunek J., 2008, The HYDRUS‐1D software package for simulating the one‐dimensional movement of water, Heat, and Multiple Solutes in Variably‐Saturated Media, Version, 4, 281

Cited by

Sorted by citations

Items 201–223 of 223

Metadata

Authors
Guo, B., Zeng, J., & Brusseau, M. L.
Affiliations
University of Arizona (US)
Corresponding author
Guo, Bo
Venue
Water Resources Research
Published
2020-02
Volume
56
Issue
2
ISSN
  • 0043-1397 (ISSN-L)
  • 1944-7973
OpenAlex
W2999663693
Cited by
224
References
74
Citations by year
2026: 45 · 2025: 37 · 2024: 38 · 2023: 27 · 2022: 31 · 2021: 37 · 2020: 9
FWCI
9.64
Type
journal article
Language
en
Open access
Locations
  • Water Resources Research (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
  • UA Campus Repository (The University of Arizona) (acceptedVersion)
Funders
National Institute of Environmental Health Sciences (P42ES004940)
Topics
  • Physical Sciences › Environmental Science › Environmental Chemistry › Per- and polyfluoroalkyl substances research
  • Physical Sciences › Environmental Science › Environmental Engineering › Groundwater flow and contamination studies
  • Physical Sciences › Engineering › Civil and Structural Engineering › Soil and Unsaturated Flow
Keywords
per- and polyfluoroalkyl substances, PFOS, vadose zone, air-water interface adsorption, solid-phase adsorption, retention factor, groundwater contamination, aqueous film-forming foam, gravity drainage, capillary retention, source zone

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.

A language model drew the claims from the paper on 2026-10-06, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-10-06 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review