Skip to main content
NCBI home page
NIHPA Author Manuscripts logoLink to NIHPA Author Manuscripts
. Author manuscript; available in PMC: 2023 Jan 1.
Published in final edited form as: Chemosphere. 2021 Aug 7;286(Pt 3):131834. doi: 10.1016/j.chemosphere.2021.131834

The Co-Transport of PFAS and Cr(VI) in Porous Media

Dandan Huang a,c, Naima A Khan d, Guangcai Wang a,b, Kenneth C Carroll d, Mark L Brusseau c,*
PMCID: PMC8634893  NIHMSID: NIHMS1733011  PMID: 34392202

Abstract

PFAS and Cr are present at some sites as co-contaminants. The objective of this research was to investigate the co-transport behavior of per- and polyfluoroalkyl substances (PFAS) and hexavalent chromium (Cr(VI)) in porous media. Miscible-displacement experiments were conducted using two soils and an aquifer sediment with different geochemical properties. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were employed as model PFAS. The retardation of PFOS was decreased in the presence of Cr(VI). Conversely, the transport and retardation of PFOA was not affected by the presence of Cr(VI). The reduction of PFOS retardation caused by Cr(VI) is likely due to sorption competition for both organic-carbon and inorganic (metal-oxides and clay minerals) domains. The relative contributions of the three soil constituents to PFOS sorption and the potential for competition between PFOS and Cr(VI) is a function of the geochemical composition of the porous media (i.e., organic carbon, metal-oxides and clay minerals). The PFAS had minimal impact on the retention and transport of Cr(VI). To our knowledge, the results presented herein represent the first reported data for PFOS and Cr(VI) co-transport in porous media. The results of this study indicate that the presence of Cr(VI) has the potential to increase the migration potential of PFOS in soil and groundwater, which should be considered when characterizing electroplating facilities, leather tanning facilities, and other co-contaminated sites.

Keywords: PFOS, Cr(VI), co-transport, porous media

Graphical Abstract

graphic file with name nihms-1733011-f0001.jpg

1. Introduction

Per- and polyfluoroalkyl substances (PFAS) have been widely used in many industrial, commercial, and military applications. The strong carbon-fluorine bond provides PFAS with high thermal, chemical, and biological stability. PFAS are contaminants of critical concern because of their persistence and widespread distribution in the environment (e.g., Ahrens, 2011; Krafft and Riess, 2015; Cousins et al., 2016; Wang et al., 2017). As a result, the transport and fate behavior of PFAS in soil and groundwater has become a recent focus of research.

Hexavalent chromium has recently received renewed attention as a contaminant of concern. One of the primary sources of hexavalent chromium is the chromic acid mist from the chrome plating industry (U.S. EPA, 1998). Perfluorooctane sulfonate (PFOS), one of the most common PFAS, was employed as a mist suppressant for many years to minimize the release of chromium during the chrome-plating process. The PFOS served to reduce the surface tension of the solution and thereby control chromium emission (U.S. EPA, 2009; Danish EPA, 2011). Hexavalent chromium is also detected at leather tanning sites, where trivalent chromium is employed to stabilize the leather by cross linking the collagen fibers during the chromium-tanning process (Hedberg, 2020). The trivalent chromium can be oxidized to hexavalent when released to the environment. PFAS are used in the leather tanning process as protective coatings on leather, and the industrial wastes such as sludge and scraps from leather tanneries are sources of PFAS and Cr(VI) (KEMI, 2015; Wang et al., 2017).

The potential exists for co-release of chromium and PFOS into the surrounding environment at electroplating facilities, leather tanning facilities, and other sites, creating a co-contaminated system. Understanding the co-transport behavior of chromium and PFOS in porous media is important for characterizing the potential health risks associated with these co-contaminated sites. To the best of our knowledge, there have been no prior published investigations of PFOS and Cr(VI) co-transport behavior in porous media. The objective of this study is to investigate the co-transport of PFAS and Cr(VI) in natural porous media. Miscible-displacement transport experiments are conducted using two soils and an aquifer sediment that comprise a range of geochemical properties. PFOS and perfluorooctanoic acid (PFOA) are employed as model PFAS. The results of the experiments are used to evaluate the impact of co-contaminant presence on retardation and transport of each contaminant.

2. Materials and Methods

PFOS (ACS# 1763-23-1, ~40% in H2O), PFOA (ACS# 335-67-1, 95% purity) and potassium dichromate (ACS# 7778-50-9, 99% purity) were purchased from Sigma-Aldrich. 2,3,4,5,6-pentafluorobenzoic acid (ACS# 602-94-8, Sigma-Aldrich, 99% purity) was used as the nonreactive tracer (NRT) to characterize the hydrodynamic conditions of the packed columns. This compound is not a PFAS. A synthetic groundwater (SGW) solution was used for all experiments. Three air-dried porous media were employed for the miscible-displacement experiments, Borden aquifer sediment, Vinton soil, and Eustis soil. The specific physical and geochemical properties are listed in Table SI-1. More details of the solution and media are presented in the Supporting Information (SI) file. The sorption of PFOS by all three media has been extensively characterized in our recent studies (Brusseau et al., 2019; Van Glubt et al., 2021; Wang et al., 2021). These data provide a robust data set to which to compare the results of the present co-transport study.

The focus of the study is on conditions relevant for PFOS transport in source areas, wherein concentrations are anticipated to be relatively high (e.g., Brusseau et al., 2020). Therefore, a PFOS input concentration (C0) of 100 μg/L (0.2 μmol/L) was used for the majority of the experiments. An input concentration of 30 mg/L (0.577 mmol/L) was used for Cr(VI). These concentrations are within the range of the concentrations reported in soil at a chrome plating waste-contaminated site (Li et al., 2017). Additional experiments were conducted using different Cr or PFOS concentrations to test potential impacts of nonlinear sorption behavior. For the Vinton soil, an experiment was conducted with a lower concentration of Cr(VI) (300 μg/L, 5.77 μmol/L). The PFOS input concentration was increased to 30 mg/L (60 μmol/L) for an experiment with Eustis soil. Finally, a set of experiments was conducted to examine the transport of PFOA in Eustis soil to provide comparison to the transport of PFOS. Conditions for all experiments are presented in Table 1. The NRT tests were conducted prior to the PFOS transport experiments. The procedures used for the experiments and chemical analysis are the same as those employed in our prior studies (Brusseau et al., 2019; Van Glubt et al., 2021; Wang et al., 2021). Additional information is presented in the SI.

Table 1.

Summary of transport experiments and results.

Porous
media		 PFAS Conca
(mg/L)		 Cr(VI)
Conc
(mg/L)		 Porosity Rc (PFAS) Rc
(Cr(VI))		 Kd (PFAS)
(cm3/g)		 PFAS Recovery (%)
Borden 0.1 30 0.356 3.2 1.1 0.4 95
0.1 - 0.334 5.8 - 0.9 88
- 30 0.347 - 1.1 - -
0.1 30 0.423 3.5 1.1 0.7 114
Vinton 0.1 - 0.437 6.2 - 1.5 99
- 30 0.423 - 1.1 - -
0.1 0.3 0.423 4.0 ~1.0 0.8 90
Eustis 0.1 30 0.36 7.9 1.1 1.4 95
0.1 - 0.355 10.1 - 1.9 121
30 30 0.352 2.2 1.2 0.25 110
30 - 0.352 3.0 - 0.4 105
30b 30 0.352 1.5 1.2 0.1 102
30b - 0.314 1.5 - 0.1 101
- 30 0.322 - 1.2 - -
- 30 0.352 - 1.1 - -
Open in a new tab
a

All data are for PFOS unless otherwise noted

b

PFOA

c

Retardation factor

The concentrations measured for the column effluent samples were used to construct breakthrough curves as a function of pore volumes of solution eluted. Retardation factors were determined by moment analysis of the breakthrough curves. This approach has been demonstrated in prior research to produce robust measurements of retardation and sorption specifically for PFAS (Van Glubt et al., 2021). Solid-phase sorption is the primary retention process for these miscible displacement experiments, and the retardation factor is given as:

R=1+Kdρbn (1)

where Kd is the solid-phase sorption coefficient (cm3/g), ρb is porous media bulk density (g/cm3), and n is porosity. The Kd value is calculated by rearranging equation (1). When sorption is nonlinear, this Kd is considered an effective value inherent to the relevant input concentration (C0) used for the experiment. The relationship between Kd and parameters of the Freundlich sorption isotherm, commonly used to represent nonlinear sorption, is given as:

Kd=KfC0N−1 (2)

where Kf is the Freundlich sorption coefficient, N is the Freundlich exponent. The robustness of this approach has been established for PFAS in prior research (e.g., Van Glubt et al., 2021).

3. Results and Discussion

3.1. Solute Transport in Single-Solute Systems

The breakthrough curves (BTCs) for the NRT are presented in Fig. SI1. They are sharp and symmetrical, with retardation factors (R) of 1. Recoveries were within measurement uncertainty of 100%. The ideal transport behavior observed for all three media indicates that the columns were well packed and not measurably influenced by nonuniform flow.

The speciation of Cr(VI) is a function of pH and other solution conditions. Cr(VI) occurs as CrO42− under the conditions of these experiments (pH=7.1, C0(Cr(VI))=30 mg/L, T=23°C). The BTCs for Cr(VI) single-solute transport experiments are nearly symmetrical (Fig. 1). Mass recoveries were within measurement uncertainty of 100%. The retardation factors ranged from 1.1 to 1.2 for the three media. The sorbed Cr(VI) concentrations range from approximately 0.6 to 0.8 μg/g for the three media. These small values indicate that Cr(VI) retention is relatively low for all three porous media.

Fig. 1.

Fig. 1

Open in a new tab

Breakthrough curves for Cr(VI) transport in three porous media, with C0=30 mg/L. No PFOS is present in solution. The input pulse varied for each experiment.

The BTCs for PFOS transport are asymmetrical and exhibit tailing for all three media, indicating the impact of nonideal sorption. This is illustrated for transport in the Eustis soil in Fig. 2a. This nonideal behavior could be caused by rate-limited sorption/desorption, nonlinear sorption, or some combination of the two. The PFOS retardation factor and Kd value for Eustis soil are larger for the lower input concentration (Table 1), indicating an impact of nonlinear sorption on the magnitude of retardation. Prior research conducted for PFOS transport in the three media showed that nonlinear sorption contributed minimally to the observed nonideal transport (asymmetry and tailing), indicating that rate-limited sorption was the primary cause (Brusseau et al., 2019; Wang et al., 2021).

Fig. 2.

Fig. 2.

Open in a new tab

Breakthrough curves for single-solute transport of PFOS and PFOA in Eustis soil (no Cr present): (a) PFOS (C0=30 mg/L) and PFOA (C0=30 mg/L); (b) PFOS (C0=0.1 mg/L and 30 mg/L). The input pulse varied for each experiment.

The retardation factors for PFOS and PFOA are 3.0 and 1.5 respectively, for the Eustis 30 mg/L input-concentration experiments (Table 1). These translate to Kd values of 0.4 and 0.1 cm3/g respectively. PFOS exhibits greater sorption than PFOA, which is anticipated due to the greater chain length of PFOS and the greater hydrophobicity and polarizability of the sulfonate head group (Higgins and Luthy, 2006; Jeon et al., 2011). This observation is consistent with prior batch (e.g., Higgins and Luthy, 2006; Zhao et al., 2014; Milinovic et al., 2015; Van Glubt et al., 2020) and transport (e.g., Brusseau et al., 2019; Van Glubt et al., 2020; Yan et al., 2020) studies. Notably, the Kd values for PFOS sorption by the Eustis soil are fully consistent with the results of batch and column isotherm measurements reported for PFOS sorption by the Eustis soil in our prior studies (Brusseau et al., 2019; Van Glubt et al., 2021), where the Kf and N are 1.07 and 0.75 respectively over a wide concentration range (from 0.01 to 30 mg/L), establishing repeatability.

Transport experiments were conducted with the lower PFOS input concentration (0.1 mg/L) for Vinton soil and Borden aquifer sediment to compare to those conducted with Eustis soil to investigate the influence of porous-medium geochemical properties on transport. The retardation of PFOS is greater for Eustis soil than for the other two media (Table 1). The R values are 10.1, 6.2, and 5.8 for Eustis soil, Vinton soil, and Borden aquifer sediment, respectively, which translate to Kd values of 1.9, 1.5 and 0.9 cm3/g, respectively. The Eustis soil is observed to have the highest sorption capacity for PFOS. Inspection of Table SI-1 shows that Eustis soil has the largest OC content of the three media. The BTC for transport in Eustis soil exhibits more extensive elution tailing compared to the other two media (Fig. 3). Notably, the least amount of tailing is observed for the Borden medium, which has the lowest OC content. As observed for the Eustis soil, the Kd value for PFOS sorption by Vinton soil is consistent with our prior reported measurements, where the Kf and N are 1.11 and 0.77 respectively over a concentration range from 0.01 to 10 mg/L.

Fig. 3.

Fig. 3

Open in a new tab

Breakthrough curves for single-solute transport of PFOS (C0=0.1 mg/L) in three porous media. The input pulse varied for each experiment.

3.2. Cr(VI) and PFAS Transport for the Co-Contaminant Systems

The BTCs for Cr(VI) transport in the co-contaminant system are essentially identical to those for the single-solute experiments (compare Fig. 1 and 4). Furthermore, the R values and sorbed Cr(VI) concentrations are the same within measurement uncertainty. This indicates that the presence of PFAS has no measurable influence on the retention and transport of Cr(VI) in these three porous media under the experiment conditions.

Fig. 4.

Fig. 4

Open in a new tab

Breakthrough curves for Cr(VI) co-transport experiments in three porous media. PFOS C0 = 0.1 or 30 mg/L; PFOA C0=30 mg/L. The input pulse varied for each experiment.

The magnitude of PFOS retardation in the co-contaminant systems is reduced compared to that for the single-solute transport experiments for all three media (see Fig. 5). The R and Kd values for the co-contaminant system are 2.2 and 0.25 cm3/g, respectively, for the high PFOS input-concentration Eustis soil experiment (Table 1). The Kd is 38% smaller compared to that for the single-solute experiments. For the lower PFOS input-concentration Eustis soil experiments, the introduction of Cr(VI) decreased the PFOS retardation factor from 10.1 to 7.9, and the Kd decreased by 26% from 1.9 to 1.4 cm3/g. Decreases in PFOS retardation and sorption in the presence of Cr(VI) are also observed for transport in Vinton soil and Borden aquifer sediment (Table 1), which are discussed below.

Fig. 5.

Fig. 5.

Open in a new tab

Breakthrough curves for transport of PFOS in the absence and presence of Cr(VI) for: (a) Eustis soil, (b) Vinton soil, and (c) Borden aquifer material. PFOS C0 = 0.1 mg/L and Cr(VI) C0 = 30 mg/L.

The ratio of Cr to PFOS in solution is nearly 3000 for the low-concentration PFOS experiments. The sorbed PFOS concentration for Eustis soil is 0.14 μg/g at the input PFOS concentration of 0.2 μmol/L, compared to a sorbed concentration of 0.90 μg/g for Cr(VI) at the input concentration of 577 μmol/L. The sorbed PFOS concentration is lower than that of Cr(VI) for the low PFOS input-concentration experiment. For the high PFOS input-concentration experiment, the Cr(VI) aqueous concentration is approximately 10-times higher than PFOS, and the sorbed concentrations are 1.3 and 7.5 μg/g for Cr(VI) and PFOS at the Cr(VI) and PFOS input concentrations of 577 and 60 μmol/L, respectively. Hence, in contrast to the low-concentration PFOS experiments, the sorbed PFOS concentration is higher than that of Cr(VI) for the high PFOS input-concentration experiments. . However, for both cases, PFOS sorption is reduced in the presence of Cr(VI).

Different results are observed for PFOA transport at the high-input concentration compared to PFOS (Fig. 6). The R and Kd values are the same for co-contaminant and single-solute experiments for PFOA. These results indicate that the presence of Cr(VI) reduced the sorption of PFOS, but has no measurable impact on the retention and transport of PFOA in Eustis soil for high PFAS concentrations. This is considered to be due in part to the lesser retention of PFOA in Eustis soil, and thus a smaller impact from Cr(VI). In addition, prior research has reported that PFOS has greater contributions of electrostatic sorption than PFOA (e.g., Jeon et al., 2011). Thus, there would be greater opportunity for competitive sorption between Cr(VI) and PFOS.

Fig. 6.

Fig. 6.

Open in a new tab

BTCs for transport of PFOA in Eustis soil: PFOA (30 mg/L) alone and PFOA (30 mg/L) with Cr(VI) (30 mg/L). (T=23 °C; v=0.5 mL/min)

Experiments were conducted with two different Cr(VI) input concentrations (577 μmol/L and 5.77 μmol/L) for the co-contaminant transport in Vinton soil. The PFOS input concentration is 0.2 μmol/L. The PFOS R and Kd values are 4.0 and 0.8 cm3/g, respectively, for the lower Cr(VI) input-concentration experiment and 3.5 and 0.7 cm3/g for the higher Cr(VI) experiment (Table 1). The presence of Cr(VI) reduced the PFOS Kd values by 47% and 53% for the lower and higher Cr(VI) C0 experiments, respectively, compared to the single-solute PFOS transport experiment in Vinton soil. The sorbed Cr concentration at the input concentration of 577 μmol/L is 0.47 μg/g, compared to a sorbed concentration of 0.07 μg/g for PFOS at the input concentration of 0.2 μmol/L. For the lower Cr(VI) input-concentration experiment, the aqueous Cr(VI) concentration is approximately 30-times higher than PFOS, and the sorbed concentrations are 0.002 and 0.08 μg/g for Cr(VI) and PFOS, respectively. Thus, the presence of Cr(VI) has a similar impact on PFOS retention and transport in Vinton soil for both Cr(VI) concentrations.

A co-contaminant experiment was conducted for Borden aquifer sediment. The input concentrations of Cr(VI) and PFOS were 577 and 0.2 μmol/L, respectively. The introduction of Cr(VI) significantly decreased the retardation factor from 6.3 to 3.2 (Table 1). This corresponds to a 60% decrease in Kd from 1.0 to 0.4 cm3/g. The sorbed PFOS concentration decreased from 0.1 to 0.04 μg/g.

3.3. Competitive Sorption Interactions

The results of the experiments discussed above show that although the sorption of Cr(VI) is relatively low for the media tested, it can significantly impact the sorption and retention of PFOS when present at sufficiently high concentrations relative to PFOS. The three porous media used for this research have different geochemical compositions, with different OC, metal-oxide, and clay-mineral contents. The Vinton soil and Borden aquifer sediment contain relatively lower OC contents but higher metal-oxide contents compared to the Eustis soil, which has a higher OC content. The clay mineral compositions also vary among the three media. The clay mineral fraction is comprised primarily of kaolinite for Eustis soil, whereas Vinton soil contains several types of clay minerals (i.e., kaolinite, vermiculite, illite and montmorillonite). Conversely, Borden aquifer sediment has only trace levels of clay minerals.

The sorption of PFOS, PFOA, and other PFAS has been reported to be predominated by soil organic carbon for some media, particularly those with relatively high OC contents (e.g., Higgins and Luthy, 2006; Guelfo and Higgins, 2013; Milinovic et al., 2015; Brusseau, 2019; Brusseau et al., 2019; Wang et al., 2021). Studies have also identified that metal-oxides contribute to PFAS sorption in some cases (e.g., Johnson et al., 2007; Knight et al., 2019; Wang et al., 2021). In addition, research has shown that PFAS can interact with clay minerals, which exhibit different PFAS sorption mechanisms through electrostatic interaction, surface complexing, and hydrogenbonding (Zhao et al., 2014; Knight et al., 2019). Given the preceding geochemical properties, it is likely that multiple soil constituents are contributing to PFOS and PFOA sorption by the three media. As a result, the relative contributions of electrostatic interaction versus hydrophobic interaction to overall sorption may vary for the three porous media, which may influence potential sorption competition between PFOS and Cr(VI).

A distributed-sorption model is used to evaluate the relative contributions of the soil constituents to PFOS sorption. A three-component model is used focusing on OC, metal-oxide, and silt+clay contents, the latter used as a surrogate for contributions from clay minerals and other inorganic (non-metal-oxide) constituents. The modeling results, detailed in Wang et al. (2021), indicate that hydrophobic interaction of PFOS with soil organic carbon is the predominant mechanism of retention for Eustis soil, which is consistent with the results of a prior study investigating PFOS sorption by the soils and aquifer sediments with different geochemical properties (Brusseau et al., 2019). Predominance of hydrophobic interaction for PFOS sorption by media with higher OC contents has been observed in several prior studies as noted above. The Kd modeling revealed that silt+clay content contributed 59 and 80% of total PFOS sorption for Vinton soil and Borden aquifer sediment, respectively. Compared to the large contribution of silt+clay to PFOS sorption, the contributions of organic carbon (39 and 19% for Vinton soil and Borden aquifer sediment) and metal-oxides (2 and 0.4% for Vinton soil and Borden aquifer sediment) to PFOS sorption were lower for both media.

The presence of Cr(VI) in the co-contaminant transport experiments caused Kd decreases of >47% for both Vinton soil and Borden aquifer sediment, but only 26% for Eustis soil. The greater reductions in Kd for Vinton soil and Borden aquifer sediment are consistent with the greater contribution from silt and clay contents for PFOS sorption for these two media. It has been demonstrated that the sulfonate group can be adsorbed onto the surface of clay minerals through outer surface complexation (Zhao et al., 2014). Additionally, the introduced Cr(VI) may compete with PFOS though surface complexation with the hydroxyl sites of clay minerals such as kaolinite and montmorillonite (Bradl, 2004). The reduction in PFOS sorption is not as significant for the Eustis soil presumably because the sorption of PFOS in Eustis soil is controlled by soil organic carbon and the contributions from the other soil components is less significant. It is possible that the impact of Cr(VI) on PFOS sorption, including that for the Eustis soil, was also influenced by interactions with organic carbon. Prior research has demonstrated that Cr(VI) is sorbed by organic carbon through interaction with positively charged sites (e.g., Arslan et al., 2010; Zhang et al., 2017).

4. Conclusions

The objective of this research was to investigate the co-transport behavior of per- and polyfluoroalkyl substances (PFAS) and hexavalent chromium (Cr(VI)) in porous media. Miscible-displacement experiments were conducted using two soils and an aquifer sediment with different geochemical properties. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were employed as model PFAS. The retardation of PFOS was decreased in the presence of Cr(VI). Conversely, the transport and retardation of PFOA at the higher concentration was not affected by the presence of Cr(VI). The reduction of PFOS retardation caused by Cr(VI) is likely due to sorption competition for both organic-carbon and inorganic (metal-oxides and clay minerals) domains. The relative contributions of the three soil constituents to PFOS sorption and the potential for competition between PFOS and Cr(VI) is a function of the geochemical composition of the porous media (i.e., organic carbon, metal-oxides and clay minerals). The PFAS had minimal impact on the retention and transport of Cr(VI). To our knowledge, the results presented herein represent the first reported data for PFOS and Cr(VI) co-transport in porous media.

The results of this research indicate that the presence of Cr(VI) has the potential to decrease the sorption and retardation of PFOS in natural porous media, especially in contaminant source areas. This would result in enhanced migration of PFOS in soil and groundwater. The presence of Cr(VI) could therefore enhance PFAS exposure potential. This potential should be considered for management of sites comprising co-contamination of PFAS and Cr(VI). The impact of Cr(VI) on the sorption and transport of PFOS is anticipated to vary as a function of concentration and porous-medium properties. A question for further investigation is whether other anionic constituents such as nitrate, sulfate, arsenate, and selenate may have a similar impact on the sorption and transport of PFOS and other PFAS.

Supplementary Material

1

Highlights:

Cr(VI) can increase the migration potential of PFOS in soil and groundwater

Cr(VI) may compete with PFOS for both organic-carbon and inorganic domains

PFOS sorption is controlled by the geochemical composition of the porous media

Acknowledgements

This research was supported by the NIEHS superfund Research Program (grant #P42 ES 4940) and the China Scholarship Council (CSC). Additional support was provided by the USDA National Institute of Food and Agriculture (Hatch project 132356), and partial support was also provided by the Department of Energy (DOE) Minority Serving Institution Partnership Program (MSIPP) managed by the Savannah River National Laboratory.

Footnotes

Credit Author Statement

Dandan Huang: Investigation, Analysis, Writing- Original draft preparation.

Naima A. Khan: Analysis, Writing- Review & Editing.

Guangcai Wang: Resources, Supervision, Writing- Review & Editing.

Kenneth C. Carroll: Resources, Supervision, Writing- Review & Editing.

Mark L. Brusseau: Conceptualization, Methodology, Resources, Supervision, Investigation, Analysis, Writing- Review & Editing.

Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Declaration of interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

  1. Ahrens L, 2011. Polyfluoroalkyl compounds in the aquatic environment: a review of their occurrence and fate. J. Environ. Monit 13, 20–31. [DOI] [PubMed] [Google Scholar]
  2. Arslan G, Edebali S, Pehlivan E, 2010. Physical and chemical factors affecting the adsorption of Cr(VI) via humic acids extracted from brown coals. Desalination 255(1-3), 117–123. [Google Scholar]
  3. Bradl HB, 2004. Adsorption of heavy metal ions on soils and soils constituents. J. Colloid Interf. Sci 277, 1–18. [DOI] [PubMed] [Google Scholar]
  4. Brusseau ML, 2019. Estimating the relative magnitudes of adsorption to solid-water and air/oil-water interfaces for per- and poly-fluoroalkyl substances. Environ. Pollut 254, 113102. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Brusseau ML, Khan N, Wang Y, Yan N,Van Glubt S, Carroll KC, 2019. Nonideal transport and extended elution tailing of PFOS in soil. Environ. Sci. Technol 53(18), 10645–10664. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Brusseau ML , Anderson RH , Guo B , 2020. PFAS concentrations in soils: back- ground levels versus contaminated sites. Sci. Total Environ 740, 140017. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Cousins IT, Vestergren R, Wang Z, Scheringer M, McLachlan MS, 2016. The precautionary principle and chemicals management: The example of perfluoroalkyl acids in groundwater. Environ. Int 94, 331–340. [DOI] [PubMed] [Google Scholar]
  8. Danish EPA, 2011. Substitution of PFOS for Use in Nondecorative Hard Chrome Plating. Danish Environmental Protection Agency, Copenhagen. [Google Scholar]
  9. Guelfo JL, Higgins CP, 2013. Subsurface transport potential of perfluoroalkyl acids at aqueous film-forming foam (AFFF)-impacted sites. Environ. Sci. Technol 47, 4164–4171. [DOI] [PubMed] [Google Scholar]
  10. Hedberg YS, 2020. Chromium and leather: a review on the chemistry of relevance for allergic contact dermatitis to chromium. J. Leather. Sci. Eng 2(1), 20. [Google Scholar]
  11. Higgins C, Luthy R, 2006. Sorption of perfluorinated surfactants on sediments. Environ. Sci. Technol 40(23), 7251–6. [DOI] [PubMed] [Google Scholar]
  12. Jeon J, Kannan K, Lim BJ, An KG, Kim SD, 2011. Effects of salinity and organic matter on the partitioning of perfluoroalkyl acid (PFAs) to clay particles. J. Environ. Monit 13, 1803–1810. [DOI] [PubMed] [Google Scholar]
  13. Johnson RL, Anschutz AJ, Smolen JM, Simcik MF, Penn RL, 2007. The adsorption of perfluorooctane sulfonate onto sand, clay, and iron oxide surfaces. J. Chem. Eng. Data 52, 1165–1170. [Google Scholar]
  14. KEMI (Swedish Chemicals Agency), 2015. Occurrence and use of highly fluorinated substances and alternatives. http://www.kemi.se/en/global/rapporter/2015/report-7-15-occurrence-and-use-of-highlyfluorinated-substances-and-alternatives.pdf.
  15. Knight ER, Janik LJ, Navarro DA, Kookana RS, McLaughlin MJ, 2019. Predicting partitioning of radiolabelled 14C-PFOA in a range of soils using diffuse reflectance infrared spectroscopy. Sci. Total Environ 686, 505–513. [DOI] [PubMed] [Google Scholar]
  16. Krafft MP, Riess JG, 2015. Per- and polyfluorinated substances (PFASs): Environmental challenges. Curr. Opin. in Colloid Interface Sci 20(3), 192–212. [Google Scholar]
  17. Li B, Bao Y, Xu Y, Xie S, Huang J, 2017. Vertical distribution of microbial communities in soils contaminated by chromium and perfluoroalkyl substances. Sci. Total Environ 599–600, 156-164. [DOI] [PubMed] [Google Scholar]
  18. Milinovic J, Lacorte S, Vidal M, Rigol A, 2015. Sorption behavior of perfluoroalkyl substances in soils. Sci. Total Environ 511, 63–71. [DOI] [PubMed] [Google Scholar]
  19. U.S. EPA, 1998. Toxicological Review of Hexavalent Chromium. In Support of Summary Information on the Integrated Risk Information System (IRIS). U.S. Environmental Protection Agency, Washington, DC. [Google Scholar]
  20. U.S. EPA, 2009. PFOS Chromium Electroplater Study. U.S. Environmental Protection Agency, Washington, DC. [Google Scholar]
  21. Van Glubt S, Brusseau ML, Yan N, Huang D, Khan N, Carroll KC, 2021. Column versus batch methods for measuring PFOS and PFOA sorption to geomedia. Environ. Pollut 268, 115917. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Wang Z, Dewitt JC, Higgins CP, Cousins IT, 2017. A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)? Environ. Sci. Technol 51(5), 2508–2518. [DOI] [PubMed] [Google Scholar]
  23. Wang Y, Khan N, Huang D, Carroll KC, Brusseau ML, 2021. Transport of PFOS in aquifer sediment: Transport behavior and a distributed-sorption model. Sci. Total Environ 779, 146444. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Yan N, Ji Y, Zhang B, Zheng X, Brusseau ML, 2020. Transport of GenX in Saturated and Unsaturated Porous Media. Environ. Sci. Technol 54, 19, 11876–11885. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Zhao L, Bian J, Zhang Y, Zhu L, Liu Z, 2014. Comparison of the sorption behaviors and mechanisms of perfluorosulfonates and perfluorocarboxylic acids on three kinds of clay minerals. Chemosphere 114, 51–58. [DOI] [PubMed] [Google Scholar]
  26. Zhang J, Chen L, Yin H, Jin S, Liu F, Chen H, 2017. Mechanism study of humic acid functional groups for Cr(VI) retention: Two-dimensional FTIR and 13C CP/MAS NMR correlation spectroscopic analysis. Environ. Pollut 225, 86–92. [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

1
NIHMS1733011-supplement-1.pdf (148.1KB, pdf)

RESOURCES