Spatial distribution and mass transport of Perfluoroalkyl Substances (PFAS) in surface water: A statewide evaluation of PFAS occurrence and fate in Alabama

https://doi.org/10.1016/j.scitotenv.2022.155524Get rights and content

Highlights

  • This study evaluated the distribution and mass transport of 17 PFAS in Alabama.

  • PFAS were detected in 88% of surface water samples, reaching up to 237 ng L−1.

  • Short-chain PFAS accounted for the majority of the contamination in the samples.

  • Increases in mass fluxes were observed as rivers moved through Alabama.

  • Mass flux is a simple approach to understand mass transport trends in large rivers.

Abstract

Per- and polyfluoroalkyl substances (PFAS) have been previously detected near suspected sources in Alabama, but the overall extent of contamination across the state is unknown. This study evaluated the spatial distribution of 17 PFAS within the ten major river basins in Alabama and provided insights into their transport and fate through a mass flux analysis. Six PFAS were identified in 65 out of the 74 riverine samples, with mean ∑6PFAS levels of 35.2 ng L−1. The highest ∑6PFAS concentration of 237 ng L−1 was detected in the Coosa River, a transboundary river that receives discharges from multiple sources in Alabama and Georgia. PFAS distribution was not observed to be uniform across the state: while the Coosa, Alabama, and Chattahoochee rivers presented relatively high mean ∑6PFAS concentrations of 191, 100 and 28.8 ng L−1, respectively, PFAS were not detected in the Conecuh, Escatawpa, and Yellow rivers. Remaining river systems presented mean ∑6PFAS concentrations between 7.94 and 24.7 ng L−1. Although the short-chain perfluoropentanoic acid (PFPeA) was the most detected analyte (88%), perfluorobutanesulfonic acid (PFBS) was the substance with the highest individual concentration of 79.4 ng L−1. Consistent increases in the mass fluxes of PFAS were observed as the rivers flowed through Alabama, reaching up to 63.3 mg s−1, indicating the presence of numerous sources across the state. Most of the mass inputs would not have been captured if only aqueous concentrations were evaluated, since concentration is usually heavily impacted by environmental conditions. Results of this study demonstrate that mass flux is a simple and powerful complementary approach that can be used to broadly understand trends in the transport and fate of PFAS in large river systems.

Introduction

Per- and polyfluoroalkyl substances (PFAS) are the focus of thousands of studies due to their adverse health effects in humans and wildlife. PFAS encompass a large group of anthropogenic organic substances widely used in industrial applications and consumer products, including in the coating of cookware and food packaging, stain- and water-repellent products and fabrics, as well as in the formulation of aqueous film forming foam (AFFF) fire extinguishers, ski wax, and much more (Johns and Stead, 2000; KEMI, 2015; Pan et al., 2018). In the late 1990s, 3M reported to the United States Environmental Protection Agency (US EPA) evidence that certain PFAS could bioaccumulate in humans (3M, 1998) and agreed to end the production of perfluorooctanesulfonic acid (PFOS) and its related salts by 2002 (3M, 2000). Since then, several studies have reported that certain PFAS might have negative health impacts in humans, including carcinogenic (Steenland and Winquist, 2021) and endocrine disrupting (Gong et al., 2019) effects, increased blood cholesterol levels (Seo et al., 2018), and obesity (Braun, 2017). In wildlife, PFAS can bioaccumulate and biomagnify through food chains (Xu et al., 2014), inhibit growth (McCarthy et al., 2017), and act as endocrine disruptors (Pedersen et al., 2016). Thus, the presence of PFAS in aquatic environments is of great concern.

Due to their stability and heterogeneity, the remediation of PFAS-contaminated waste is challenging (Ross et al., 2018), and PFAS are often discharged into the environment without proper treatment. Sources include municipal wastewater treatment plants (WWTPs), industrial facilities, landfills, airports, military bases, and firefighting training facilities, among others (Hu et al., 2016). As a result, PFAS have been identified on every continent, from remote Antarctica (Casal et al., 2017) to populous areas of Asia (Pan et al., 2017; Zushi et al., 2011) and Europe (Gobelius et al., 2018; Munoz et al., 2015). In the US, Alabama is a particular hotspot for PFAS. Previous studies, conducted in 2002 and 2017, identified an area of increased PFAS concentration in the Tennessee River downstream of several chemical facilities, including a 3M plant (Hansen et al., 2002; Newton et al., 2017). The 2017 study also identified nine previously unknown PFAS and two other novel substances that were structurally similar to existing PFAS (Newton et al., 2017). Even more troublesome, the Decatur WWTP distributed over 34,000 metric tons of biosolids contaminated with PFAS to local farmers between 1995 and 2008 (Lindstrom et al., 2011). Lindstrom et al. (2011) found PFAS levels up to 31,906 ng L−1 in surface water near fields that received the contaminated biosolids. In response, the Alabama Department of Environmental Management (ADEM) announced a consent order with 3M, stating that the company must remediate contaminated sites in the Decatur area, as well as “monitor, test, and research impacts of exposure” (ADEM, 2020). Similarly, high levels of PFAS were also identified in the Coosa River (Lasier et al., 2011) – the main drinking water source for several cities in Alabama. The City of Gadsden, AL is currently litigating against more than 30 textile companies located in Georgia, arguing that these companies are responsible for the high levels of PFAS in the Coosa River. Recently, ADEM conducted a survey in 290 public water systems (PWS) for 18 PFAS (ADEM, 2021). According to their report, PFAS were found in 57 PWS, with ∑PFAS reaching up to 384 ng L−1, indicating the presence of PFAS in their corresponding source waters, as these substances are not likely to be removed through conventional treatment processes (Crone et al., 2019).

While previous studies have greatly enhanced the understanding on PFAS sources and their overall distribution, much remains unknown regarding their transport and fate in the environment. This is partially related to the fact that most studies express PFAS contamination in terms of concentration, which is not sufficient to track contamination in large river systems. This is because aqueous concentrations are affected by a variety of environmental factors, such as precipitation and stormwater runoff. Thus, considering aqueous concentration alone can lead to erroneous conclusions regarding the amount and transport of contaminant mass through interconnected river systems. Moreover, identification of sources can be difficult, as variable environmental conditions may mask potential PFAS inputs. Mass flux analysis is a simple complimentary approach that combines volumetric discharge and aqueous concentration. Most studies have used the concept of mass flux to estimate yearly mass discharge of tributaries into lakes or bays, using an annual average flow rate. For instance, Ma et al. (2018) calculated the fluxes of tributaries discharging into Taihu Lake and used them to determine sources, while Zhao et al. (2020) calculated the mass discharge of tributaries into the Bohai Sea. Results from those studies enhanced the understanding of the fate of PFAS in the environment, but not so much about their transport behavior. On the other hand, Nakayama et al. (2010) performed a mass flux analysis to track the mass transport of PFAS in the Upper Mississippi River Basin, by calculating the mass flux for sampling points using a 72-h average volumetric flow rate.

The ultimate fate of PFAS in the environment remains unclear. Studies have shown that some PFAS can be removed from water by partitioning to sediments and suspended particulates, volatilization, and sequestration by biota and wildlife (Casal et al., 2017; Liu et al., 2019; Munoz et al., 2019), depending on their chemical properties. Regardless of the environmental compartment, most terminal (stable) PFAS will persist virtually unchanged (Guelfo and Adamson, 2018), hence their nickname “forever chemicals”. Thus, this study aims to determine the spatial distribution of seventeen PFAS in surface water in Alabama and identify trends in their transport behavior through a mass flux analysis. Results of the mass flux analysis were also used to identify locations within the state serving as potential PFAS source areas. This is the first study to use mass flux analysis to systematically track PFAS contamination in multiple river systems at a state level in the US and demonstrates that mass flux analysis is a broadly applicable, reasonably simple approach for capturing large-scale trends in the transport of PFAS through interconnected surface water systems.

Section snippets

Chemicals and reagents

Target analytes include six perfluorocarboxylic acids (PFBA, PFPeA, PFHxA, PFHpA, PFOA, and PFNA), six perfluorosulfonic acids (PFBS, PFPeS, PFHxS, PFHpS, PFOS, and PFNS), and five perfluoroethers (HFPO-DA, NaDONA, PF4OPeA, PF5OHxA, and 3,6-OPFHpA). For the above analytes, eleven are considered short-chain PFAS (PFBA, PFPeA, PFHxA, PFHpA, PFBS, PFPeS, and all the perfluoroethers). Analytical grade PFAS standards were purchased from Wellington Laboratories (Ontario, Canada). The molecular

PFAS profile in Alabama

Of the seventeen target analytes, only six were detected, including three short-chain and one long-chain perfluorocarboxylic acids (PFCAs): PFPeA, PFHxA, PFHpA, and PFOA, and one short-chain and one-long chain perfluorosulfonic acids (PFSAs), PFBS and PFOS. The perfluoroethers were not found in any of the samples. Despite the relatively low number of detected analytes, at least one PFAS was found in 88% (n = 65) of all surface water samples. The short-chain PFPeA was the most detected

Conclusions

The results of this study raise important considerations for the possible implications of PFAS to humans and wildlife in Alabama. PFAS were found to be ubiquitous in the majority of rivers and tributaries sampled, being detected in 88% of surface water samples, even in less industrialized areas, with ∑6PFAS levels reaching up to 237 ng L−1. PFAS can pose a risk to wildlife, especially in rivers where PFAS were found at higher concentrations. This could also indirectly affect humans that consume

Funding source

This work was supported by the Auburn University Presidential Awards for Interdisciplinary Research (PAIR) program to the Emerging Contaminants Research Team (ECRT) and the Auburn University Presidential Graduate Research Fellowship.

Funding sources had no involvement in the conduct of this research.

CRediT authorship contribution statement

Roger L. Viticoski: Conceptualization, Investigation, Methodology, Writing – original draft. Danyang Wang: Methodology, Formal analysis, Writing – review & editing. Meredith A. Feltman: Methodology, Formal analysis, Writing – review & editing. Vanisree Mulabagal: Formal analysis, Investigation, Supervision, Writing – review & editing. Stephanie R. Rogers: Methodology, Writing – review & editing. David M. Blersch: Methodology, Writing – review & editing. Joel S. Hayworth: Funding acquisition,

Declaration of competing interest

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.

Acknowledgments

The authors would like to thank the graduate students Clayton Stone, Caren Custodio Mendonca, Laura Gomez Arias, Julia Bitencourt, and Andresa Bezerra for their support during sample collection.

References (63)

  • X. Ma et al.

    Riverine inputs and source tracing of perfluoroalkyl substances (PFASs) in Taihu Lake,China

    Sci. Total Environ.

    (2018)
  • V. Mulabagal et al.

    A rapid UHPLC-MS/MS method for simultaneous quantitation of 23 perfluoroalkyl substances (PFAS) in estuarine water

    Talanta

    (2018)
  • G. Munoz et al.

    Spatial distribution and partitioning behavior of selected poly- and perfluoroalkyl substances in freshwater ecosystems: a French nationwide survey

    Sci. Total Environ.

    (2015)
  • G. Munoz et al.

    Temporal variations of perfluoroalkyl substances partitioning between surface water, suspended sediment, and biota in a macrotidal estuary

    Chemosphere

    (2019)
  • K.E. Pedersen et al.

    Per- and polyfluoroalkyl substances (PFASs) - new endocrine disruptors in polar bears (Ursus maritimus)?

    Environ. Int.

    (2016)
  • S.H. Seo et al.

    Influence of exposure to perfluoroalkyl substances (PFASs) on the Korean general population: 10-year trend and health effects

    Environ. Int.

    (2018)
  • K. Steenland et al.

    PFAS and cancer, a scoping review of the epidemiologic evidence

    Environ. Res.

    (2021)
  • N. Wang et al.

    6:2 fluorotelomer sulfonate aerobic biotransformation in activated sludge of waste water treatment plants

    Chemosphere

    (2011)
  • Z. Wang et al.

    Fluorinated alternatives to long-chain perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs) and their potential precursors

    Environ. Int.

    (2013)
  • F. Wang et al.

    Influence of cations on the partition behavior of perfluoroheptanoate (PFHpA) and perfluorohexanesulfonate (PFHxS) on wastewater sludge

    Chemosphere

    (2015)
  • J. Xu et al.

    Bioaccumulation and trophic transfer of perfluorinated compounds in a eutrophic freshwater food web

    Environ. Pollut.

    (2014)
  • Z. Zhao et al.

    Emerging and legacy per- and polyfluoroalkyl substances in water, sediment, and air of the Bohai Sea and its surrounding rivers

    Environ. Pollut.

    (2020)
  • Y. Zhu et al.

    Household low pile carpet usage was associated with increased serum PFAS concentrations in 2005–2006

    Environ. Res.

    (2021)
  • Letter to the US EPA - TSCA Section 8(e) -- Perfluorooctane Sulfonate

    (1998)
  • Letter to the US EPA: Phase-out Plan for POSF-Based Products

    (2000)
  • ADEM
  • ADEM

    Final Report: 2020 Per- and Polyfluoroalkyl Substances (PFAS) Sampling Program

    (2021)
  • A.A. Aquilina-Beck et al.

    Uptake and biological effects of perfluorooctane sulfonate exposure in the adult eastern oyster Crassostrea virginica

    Arch. Environ. Contam. Toxicol.

    (2020)
  • K.A. Barzen-Hanson et al.

    Discovery of 40 classes of per- and polyfluoroalkyl substances in historical aqueous film-forming foams (AFFFs) and AFFF-impacted groundwater

    Environ. Sci. Technol.

    (2017)
  • J.P. Benskin et al.

    Observation of a novel PFOS-precursor, the perfluorooctane sulfonamido ethanol-based phosphate (SAmPAP) diester, in marine sediments

    Environ. Sci. Technol.

    (2012)
  • A. Blum et al.

    The Madrid statement on poly- and perfluoroalkyl substances (PFASs)

    Environ. Health Perspect.

    (2015)
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