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Environmental Fate and Transport for,Per and Polyfluoroalkyl Substances continued. over a million gallons of ECF based AFFF in their inventory as of 2011 Darwin 2011 Studies to date show ECF based. AFFF is the dominant source of PFAS at AFFF impacted sites likely due to the longer period of ECF based AFFF use. and the relative coincidence of implementation of engineering controls for releases and wider use of telomerized AFFF. Pancras et al 2016 Anderson et al 2016 Fluorotelomerization derived AFFFs are still manufactured and used in the. United States but have been reformulated to limit if not eliminate long chain PFAS. 2 1 1 AFFF releases, AFFF is released to the environment under various scenarios see Figure 1 Although fire training areas FTAs have. received the most attention AFFF use at military and civilian facilities is highly varied In addition to FTAs many other. sites are also likely affected by AFFF due to past emergency response incidents operational requirements that mandated. periodic equipment calibrations on emergency vehicles and episodic discharge of AFFF containing fire suppression. systems within large aircraft hangars and buildings Anderson et al 2016 Thalheimer et al 2017 Accidental releases. of AFFF from storage tanks railcars and piping during delivery or transfer have also occurred Once released to the. environment AFFF can contaminate soil surface water and groundwater. Figure 1 Conceptual site model for fire training areas. Source Adapted from figure by L Trozzolo TRC used with permission. AFFF impacted sites often are also contaminated with petroleum hydrocarbons from unburned fuel PFAS and. hydrocarbon plumes at these sites may follow the same flow paths though the extent of contamination may be. significantly different These co contaminants particularly light nonaqueous phase liquids LNAPLs may affect the fate. and transport of AFFF derived PFAS Guelfo and Higgins 2013 Lipson Raine and Webb 2013 McKenzie et al 2016. Certain air based or in situ oxidation remedial activities aimed at treating co contaminants may affect PFAS composition. fate and transport as well McKenzie et al 2015 Additionally the altered soil and groundwater geochemistry and redox. conditions may result in oxidation of some PFAS precursor compounds degrading them to terminal PFAAs Harding. Marjanovic et al 2016 McKenzie et al 2016 McGuire et al 2014 In addition to AFFF firefighting foams may also. consist of fluoroprotein and film forming fluoroprotein foam. 2 2 Industrial Sites, Industrial source sites include primary manufacturing facilities where PFAS containing products are synthesized and. made into products or chemical feedstocks or where PFAS are used as processing aids in fluoropolymer production. where PFAS are not intended to be in the final product Secondary manufacturing facilities may use these products. or feedstocks as part of industrial processes such as the coating application to finished products In some industrial. settings PFAS may be used for worker safety purposes such as using PFOS based materials to suppress harmful. mists PFAS composition and release mechanisms will vary for each facility but general pathways are illlustrated in. Environmental Fate and Transport for,Per and Polyfluoroalkyl Substances continued. Figure 2 Conceptual site model for industrial sites. Source Adapted from figure by L Trozzolo TRC used with permission. Manufacturing facilities that may be sources of PFAS releases to the environment include textile and leather processors. paper mills metal finishers wire manufacturers plating facilities manufacturers as well as facilities using surfactants. resins molds plastics photolithography and semiconductors see the History and Use fact sheet for more information. Industrial facilities may release PFAS to the environment via wastewater discharges see Section 2 4 on and off site. disposal of wastes accidental releases such as leaks and spills and stack emissions Stack emissions may result in. aerial deposition of PFAS to soil and surface water with subsequent infiltration to groundwater within the airshed of the. facility as shown in Figure 2 Davis et al 2007 Shin et al 2011 Stack emissions may result in short and long range air. transport of PFAS PFAS in aerosols and adsorbed on particles are more likely to be deposited near the source while. long range transport typically involves PFAS vapors Industrial facilities may also contain areas where fire training or fire. response has occurred AFFF storage areas and AFFF fire suppression systems inside buildings. The composition of PFAS released from industrial facilities depends on the type of PFAS produced or used by the. facility For example textile coating operations may use water emulsion or powdered feedstocks that contain greater. proportions of PFCAs compared to PFSAs Lassen et al 2015 Gremmel Fr mel and Knepper 2016 In contrast to. AFFF release sites industrial sites may be less likely to co release contaminants that affect redox or other subsurface. fate and transport conditions unless the site also includes AFFF releases from historical fire training or fire suppression. activities,2 3 Landfills, Landfills are sources of PFAS because they are the ultimate repositories not only for PFAS contaminated industrial.
waste sewage sludge and waste from site mitigation but also for PFAS bearing consumer goods treated with. hydrophobic stain resistant coatings Busch et al 2010 Eggen Moeder and Arukwe 2010 Given the production. timeline of PFAS consumer products landfilled since the 1950s are potential sources to the environment Industrial waste. can be a significant source of PFAS in landfills particularly those that accept waste from the production or application of. PFAS Oliaei et al 2013 In addition many landfills accept sewage sludge from wastewater treatment facilities that may. contain PFAS Figure 3 includes illustrations of landfills and wastewater treatment plants WWTPs sources. Environmental Fate and Transport for,Per and Polyfluoroalkyl Substances continued. Figure 3 Conceptual site model for landfills and WWTPs. Source Adapted from figure by L Trozzolo TRC used with permission. 2 3 1 Landfill Construction, Landfills are either lined or unlined Figure 3 Municipal solid waste construction and demolition and industrial landfills. constructed since the 1990s are required by federal or state regulations to install a composite liner a layer of compacted. soil and a leachate collection system 40 CFR 258 40 Leachate collected from landfills is typically treated on site. or transported to either a nearby municipal WWTP or evaporation ponds The processes for managing leachate have. implications on the ultimate fate and transport of PFAS If liners or leachate collection systems fail PFAS may directly. enter the environment Landfills constructed before the 1990s are not required to have synthetic flexible membrane. liners compacted soil liners or leachate collection systems causing waste to be in direct contact with underlying soil or. groundwater Therefore unlined landfills have a higher potential of contributing PFAS to groundwater Oliaei et al 2013. Landfill caps reduce infiltration of water to waste and may reduce the overall mass of PFAS entering the environment. from a landfill but more research on their effectiveness is needed Hamid Li and Grace 2018. 2 3 2 Waste Age, Landfills containing sources of PFAS will continue to release PFAS at slow but relatively steady rates for decades. following initial placement In modeled anaerobic landfill reactors most of the release is attributed to biological not. physical mechanisms indicating that the low solubility of the compounds is not solely responsible for slow release rates. from landfills Allred et al 2015 Lang et al 2016 While landfill leachate PFAS concentrations are relatively high landfill. leachate generally is considered only a minor source to the environment because the volume of leachate generated. annually is low compared to the flow volume in most WWTPs Busch et al 2010 Legacy industrial waste landfills. however may constitute a major source to the environment ATSDR 2008 2012. 2 3 3 PFAS Composition from Landfills, Relative concentrations of PFAS in leachate and groundwater from landfills are different than those at WWTPs and. AFFF contaminated sites PFAS with fewer than eight carbons tend to dominate landfill leachate because they are less. hydrophobic and therefore more likely to partition to the aqueous phase Huset et al 2011 Higgins and Luthy 2007. In particular 5 3 fluorotelomer carboxylic acid FTCA is a common and often dominant constituent of PFAS found in. landfills and is released from carpet in model anaerobic landfill reactors This compound could prove to be an indicator. of PFAS in the environment originating from landfills Lang et al 2017 2016 PFAS may also be released to the air from. landfills predominantly as fluorotelomer alcohols FTOHs and perfluorobutanoate PFBA Ahrens et al 2011a PFAS. release rates vary with time for a given waste mass with climate for example rainfall as the apparent driving factor for. the variations Lang et al 2017 Benskin et al 2012,2 4 Wastewater Treatment Plants.
Municipal and industrial WWTPs can provide the following pathways for PFAS to the environment point source. discharges of effluent leakage or unintended releases from surface impoundments air emissions or disposal of. biosolids and other byproducts generated during the treatment process see Figure 3 The composition of PFAS in these. Environmental Fate and Transport for,Per and Polyfluoroalkyl Substances continued. media is a function of the different sources and processes Chen Lo and Lee 2012 Oliaei et al 2006 Fr mel et al 2016. Schultz et al 2006 including, type and concentration of PFAS received by the WWTP. biological and chemical transformation of polyfluorinated substances to intermediate and terminal degradation. products such as perfluoroalkyl acids PFAAs,physical or chemical partitioning or both. At WWTPs PFAAs may be created from the oxidation of polyfluorinated precursors during the treatment process Oliaei. Kriens and Kessler 2006 Fr mel et al 2016 Furthermore PFAS could be concentrated in solid waste for example. sewage sludge throughout the treatment process Schultz et al 2006 Depending on waste management and disposal. practices this solid waste could contaminate groundwater surface water or both PFAS may also be introduced to the. environment through the land application of biosolids as a beneficial soil amendment potentially allowing PFAS to enter. surface water through runoff or infiltrate to groundwater Lindstrom et al 2011 The potential effects on groundwater or. surface water depend on the amount and composition of PFAS present in biosolids soil properties infiltration rate and. land application practices While further transformation of polyfluorinated substances in land applied biosolids to PFAAs. has been suggested Sepulvado et al 2011 other evidence suggests that some polyfluorinated substances remain in. biosolids amended soils for many years Rich et al 2015. 3 Fate and Transport Processes, Partitioning transport and transformation of PFAS occurs across multiple media types While most research literature. focuses on PFAAs especially PFOS and PFOA processes affecting precursor PFAS that can degrade to PFAAs over. time are also important Figures 1 through 3 illustrate these processes for the four main sources of PFAS See Section 4. for media specific discussions of fate and transport. 3 1 Partitioning, PFAS most commonly detected in the environment typically have a carbon fluorine tail and a nonfluorinated head.
consisting of a polar functional group The tail is hydrophobic and lipophobic while the head groups are polar and. hydrophilic The competing tendencies of the head and the tail can lead to a wide distribution in the environment The tail. and head structure are illustrated for PFOS and PFOA in the following figure. Perfluorooctane sulfonate PFOS Partitioning Summary. Multiple partitioning mechanisms, Tail F3C CF2 CF2 CF2 CF2 CF2 CF2 CF2 SO3 Head affect PFAS hydrophobic and. lipophobic effects electrostatic,interactions and interfacial behaviors. PFSAs are more strongly sorbed than,Perfluorooctane carboxylate PFOA. their PFCA homologues, F3C CF2 CF2 CF2 CF2 CF2 CF2 CO2 Head Longer chain PFAAs are more strongly. sorbed than shorter chain PFAAs, Figure 4 The tail and head structure of PFOS and PFOA molecules PFAAs are.
o relatively mobile in groundwater, Given heterogeneous subsurface environments multiple partitioning but tend to associate with the. mechanisms should be considered when characterizing PFAS fate and organic carbon fraction of soil and. transport sediment,o less volatile than many other. Important PFAS partitioning mechanisms include hydrophobic and. groundwater contaminants, lipophobic effects electrostatic interactions and interfacial behaviors. The hydrophobic and lipophobic effects drive the association with organic o sometimes transported on airborne. carbon in soils a process PFAS has in common with other organic particles and. contaminants for example chlorinated solvents Electrostatic interactions o generated by transformation of. are a function of the charge of the polar functional group at the head of volatile precursors. the molecule For instance natural soils and aquifer materials often have. a net negative surface charge that can repel the negatively charged heads. Environmental Fate and Transport for,Per and Polyfluoroalkyl Substances continued. of PFAAs Because the head and the tail compete partitioning to interfaces of environmental media such as soil water. water air and water NAPL co contaminants can occur Guelfo and Higgins 2013 McKenzie et al 2016 Brusseau 2018. The partitioning behavior of PFCAs and PFSAs has been studied more in depth than that of other PFAS At relevant. environmental pH values PFCAs and PFSAs are present as organic anions and are therefore relatively mobile in. groundwater Xiao et al 2015 but tend to associate with the organic carbon fraction that may be present in soil or. sediment Higgins and Luthy 2006 Guelfo and Higgins 2013 When sufficient organic carbon is present organic carbon. normalized distribution coefficients Koc values can help in evaluating transport potential though other geochemical. factors for example pH and presence of polyvalent cations may also affect PFAS sorption to solid phases Table 3 1. provided as a separate Excel file presents the available Koc values for commonly detected PFAAs and a several other. PFAS often detected at release sites, Sorption and retardation generally increase with increasing perfluoroalkyl tail length Higgins and Luthy 2006 Guelfo and.
Higgins 2013 Sepulvado et al 2011 indicating that the short chain PFSAs for example perfluorobutane sulfonic acid. PFBS and PFCAs for example perfluorohexanoic acid PFHxA are retarded less than their long chain counterparts. PFOS and PFOA respectively In addition PFSAs tend to sorb more strongly than PFCAs of equal chain length Higgins. and Luthy 2006 and branched isomers have less sorption than linear K rrman et al 2011 Sorption of PFCAs and. PFSAs is also affected by soil solution chemistry with decreased pH and increased levels of polyvalent cations for. example Ca2 leading to increased sorption and retardation Higgins and Luthy 2006 McKenzie et al 2015. PFAAs are in general far less volatile than many other groundwater contaminants Measured vapor pressures for some. select PFAAs are available including the acidic forms of PFOA perfluorononanoic acid PFNA perfluorodecanoic acid. PFDA perfluoroundecanoic acid PFUnA and perfluorododecanoic acid PFDoA Barton Botelho and Kaiser 2008. Kaiser et al 2005 Measured vapor pressures are also available for fluorotelomer alcohols Krusic et al 2005 Henry s Law. constants are generally unavailable for PFAAs Vapor pressures of these compounds are generally low and water solubilities. are high limiting partitioning from water to air USEPA 2000b However under certain conditions particularly within industrial. stack emissions PFAS can be transported through the atmosphere Volatiles such as FTOHs may be present in the gas. phase and anionic PFAS may be sorbed to particulates Ahrens et al 2012 see Section 4 1 for a more detailed discussion. 3 2 Transport, The resistance of most PFAS to biotic or abiotic degradation except for precursor transformation discussed in Section. 3 3 means that physical transport processes are critical for PFAS transport and potential for exposure. 3 2 1 Advection Dispersion Diffusion, Processes such as advection dispersion and diffusion can strongly influence the migration of PFAS within and between. media Advection the flow related transport of compounds within a fluid such as water or air drives PFAS mobility in. many cases such as in an expanding groundwater plume Advection however does not reduce concentration along the. flow path While advection is based solely on media properties and is independent of molecular physical or chemical. properties of the contaminant modeling the migration of PFAS due to fluid flow requires an understanding of how PFAS. interact with the surrounding medium This modeling should include the effect of sorption see Section 3 1 which is. often expressed in terms of how the contaminant velocity is reduced relative to advective velocity. Small scale changes in air and surface water velocities can disperse contaminants in multiple directions contributing. to rapid vertical mixing of PFAS and cross media transport for example surface water to sediment and deposition. from air to surface soil In groundwater dispersion is limited meaning that plumes are relatively narrow as they move. downgradient from a source Payne Quinnan and Potter 2008 When PFAS plumes are wider than expected based. on dispersion alone the plume width may reflect the contribution of nonpoint sources for example air deposition or. comingled plumes for example some fire training areas. In air and water molecules moving in response to a concentration gradient is known as diffusion In surface water and. air mixing caused by turbulence is also referred to as diffusion for example PFAS transport in oceans can be due to. eddy diffusion Lohmann et al 2013 Diffusion in groundwater is often ignored because diffusion rates are slow relative. to advection However diffusion of contaminant mass into lower permeability soils or site materials such as clays. bedrock and concrete may enhance the long term persistence of PFAS in groundwater For instance at one site PFAS. penetrated 12 cm into a concrete pad at a fire training area and diffusion was a contributing process Baduel Paxman. and Mueller 2015,Environmental Fate and Transport for. Per and Polyfluoroalkyl Substances continued,3 2 2 Deposition. Transport Summary, While many PFAS exhibit relatively low volatility airborne transport of.
some PFAS is a relevant migration pathway through industrial releases Critical PFAS transport processes. for example stack emissions Once airborne some PFAS are subject include advection dispersion. to photooxidation and transport but they can eventually accumulate to diffusion atmospheric deposition and. measurable levels in soil and surface water through atmospheric deposition leaching. Young and Mabury 2010 Ahrens and Bundschuh 2014 Rankin et al Atmospheric transport and. 2016 Atmospheric deposition can occur as dry or wet deposition both subsequent deposition can lead to. of which are relevant for PFAS Barton Kaiser and Russell 2007 Barton measurable PFAS accumulation away. Zarzecki and Russell 2010 Dreyer et al 2010 Taniyasu et al 2013 from their point of release. During dry deposition PFAS that are preferentially associated with liquid or Downward leaching of PFAS in. particle phases in air aerosols can be naturally deposited onto surfaces unsaturated soils during precipitation. by sedimentation diffusion or other processes When precipitation or irrigation events is site specific and. washes out these PFAS containing aerosols the process is known as wet occurs as a function of media and. deposition Deposition is generally considered a removal process that PFAS structural properties. reduces longer range atmospheric transport See Section 4 1 for further At high concentrations PFAAs can. discussion of atmospheric deposition of PFAS form micelles which could enhance. or reduce adsorption on carbon and,3 2 3 Leaching minerals. PFAS present in unsaturated soils are subject to downward leaching during. precipitation or irrigation events that promote dissolution of soil bound. contaminant mass Sepulvado et al 2011 Ahrens and Bundschuh 2014 This process is a potential driver of PFAS. transport from surface soils to groundwater and surface water because releases often involve surface applications. for example AFFF and biosolids or atmospheric deposition Leaching is also potentially relevant for plant uptake and. transport of PFAS contained in landfill waste without adequate leachate control Benskin et al 2012 Yan et al 2015. Lang et al 2017 Leaching potential is a function of both media properties for example pH redox conditions and. increased partitioning with organic rich soil and PFAS structural properties for example ionic charge and chain length. Gellrich Stahl and Knepper 2012 While some studies have reported PFAS transport by leaching Lindstrom et al. 2011 Filipovic et al 2015 Hellsing et al 2016 Braunig et al 2017 others have observed long term retention of longer. chain PFAS on shallow soils after extended percolation Sepulvado et al 2011 Stahl et al 2013 Anderson et al 2016. This retention may reduce the potential for PFAS exposure by several pathways for example groundwater ingestion. but may increase the long term persistence of the soil bound source Baduel Paxman and Mueller 2015. 3 2 4 Surfactant Properties and Micelle Formation, PFAS exhibit surfactant properties because they often contain hydrophobic and hydrophilic portions which affect. transport in ways that are complex and not well understood By design many PFAS preferentially form films at the air. water interface with the hydrophobic carbon fluorine C F tail oriented towards the air and the hydrophilic head group. dissolved in the water Krafft and Riess 2015 This behavior influences aerosol based transport and deposition and. suggests that PFAS accumulates at water surfaces Prevedouros et al 2006. This preference for the air water interface may also influence vadose zone transport where unsaturated conditions. provide significant air water interfacial area Adsorption of PFOS and PFOA at the air water interface can increase. the retardation factor for aqueous phase transport this interfacial process accounted for approximately 50 of the. total retention in a model system with 20 air saturation Brusseau 2018 At higher concentrations PFAAs can form. aggregates in which the hydrophilic portions interact with the water phase and the hydrophobic portions interact with. each other for example micelles or hemimicelles For PFOS the critical micelle concentrations CMC of 500 to 5 000. mg L have been reported but hemimicelles may form at concentrations as low as 0 001 times the CMC Yu et al 2009. Du et al 2014 Brusseau 2018 This tendency to aggregate may cause PFAAs to act differently at high concentrations. for example during release and could enhance or in some cases reduce adsorption on carbon and minerals in the. environment Yu et al 2009 Du et al 2014,Environmental Fate and Transport for. Per and Polyfluoroalkyl Substances continued,3 3 PFAS Transformation. Both biotic and abiotic transformations of some polyfluorinated substances. precursors may form PFAAs However PFAAs likely do not degrade or Transformation Summary. otherwise transform under ambient environmental conditions Unlike the PFAS precursor chemicals can. fully fluorinated PFAAs precursor PFAS contain carbon hydrogen C H transform to PFAAs via biotic and. and carbon oxygen C O bonds throughout the alkyl carbon chain These abiotic processes. C H and C O bonds are subject to a variety of biotic and abiotic reactions Transformation rates are highly. that ultimately form terminal end products While available studies on both variable and site specific. biotic and abiotic transformation of precursor PFAS primarily consist of. PFAAs are not known to transform, controlled laboratory experiments discussed below an increasing number.
under ambient environmental, of field studies have demonstrated the importance of precursors at a variety. conditions, of sites with different source scenarios for example Weber et al 2017. Dassuncao et al 2017,3 3 1 Abiotic Transformation, Abiotic processes that can transform precursors under ambient environmental conditions include hydrolysis photolysis. and oxidation Hydrolysis of some precursors followed by subsequent biotransformation can produce PFSAs For. example PFOS is produced from perfluorooctane sulfonyl fluoride POSF Martin et al 2010 Other hydrolysis reactions. produce PFCAs The release of PFAAs by abiotic transformation may be slow For instance Washington and Jenkins. 2015 report a half life of over 50 years for the hydrolysis of fluorotelomer derived precursors at neutral pH to form. PFOA and other PFCAs While direct photolysis of PFAS has not been observed indirect photolysis of some precursors. notably FTOHs does occur in the atmosphere and can be a significant contributor to PFCA deposition Armitage. MacLeod and Cousins 2009 Yarwood et al 2007 For example 8 2 FTOH degrades to PFOA in the atmosphere. through reactions with hydroxyl radicals and chlorine radicals with similar reactions for 6 2 and 4 2 FTOHs Ellis et al. 2004 Wallington et al 2006, Perfluoroalkanesulfonamides can also degrade abiotically through oxidation in the atmosphere to form PFCAs in yields. that may be 10x greater than FTOHs Martin et al 2006 Also oxidation of precursors by hydroxyl radicals can occur. in natural waters with the fluorotelomer derived precursors being oxidized more rapidly than ECF derived precursors. Gauthier and Mabury 2005 Plumlee McNeill and Reinhard 2009 Shorter chain PFSAs such as PFBS also can be. produced by oxidation reactions between hydroxyl radicals and sulfonamido derivatives D Eon et al 2006 Finally in. some cases abiotic precursor transformations may not initially produce any PFAA for example the formation of various. polyfluorinated sulfonamido intermediate compounds from ECF derived precursors though eventual formation of PFAAs. may still be possible Martin et al 2010,3 3 2 Biotic Transformation.
While PFOA PFOS and all other PFAAs are resistant to microbial degradation numerous studies have reported. biotransformations of various precursors similar to the abiotic transformations discussed in Section 3 3 1 The current. literature indicates, Numerous aerobic biotransformation pathways exist with relatively rapid kinetics. All polyfluorinated precursors may have the potential to aerobically biotransform to PFAAs. Aerobic biotransformation of various fluorotelomer derived precursors to PFCAs including PFOA occurs for example. Harding Marjanovic et al 2015 D Agostino and Mabury 2017. Aerobic biotransformation of various ECF derived precursors to PFSAs including PFOS occurs Zhang et al 2017. Mejia Avenda o and Liu 2015 Mejia Avenda o et al 2016. Fewer studies have been published regarding anaerobic biotransformation of PFAS FTOHs have been observed to. biotransform anaerobically but appear to form stable polyfluorinated acids rather than PFCAs or PFSAs Zhang et al. 2013 Allred et al 2015, Note that fluorotelomer derived precursors do not form PFSAs while degradation of ECF derived precursors may form. both PFSAs and PFCAs The extent to which ECF derived precursors form PFCAs in situ is under study along with other. critical factors such as ambient biotransformation rates In general however biotransformation rates are probably site. specific and could be so slow as to be inconsequential at some sites. Environmental Fate and Transport for,Per and Polyfluoroalkyl Substances continued. 4 PFAS Occurrence by Medium, PFAS occurrence in various environmental media is an active area of research The material presented here is not the. result of an exhaustive literature review but is included to provide a relative understanding of PFAS concentrations As. discussed in the Site Characterization Considerations Sampling Precautions and Laboratory Analytical Methods fact. sheet analytical methods are still being optimized and standardized thus it is difficult to compare results between. studies and conclusions may change over time Media types presented here include air soil and sediment groundwater. surface water and biota The processes that influence media specific PFAS concentrations are illustrated in Figures 1. Certain PFAS are found in ambient air with elevated concentrations observed or expected in urban areas nearest to. emission sources such as manufacturing facilities WWTPs fire training facilities and landfills Barton et al 2006 Ahrens. et al 2011a Liu et al 2015a Table 4 1 includes summary information about occurrence of PFAS in outdoor air from. selected studies, Although outdoor air containing PFAS can enter buildings the presence of indoor sources can cause indoor air.
concentrations of certain PFAS to be higher than outdoor air concentrations Fromme et al 2015 Shoeib et al 2011. Examples of indoor sources of PFAS include many consumer products such as stain resistant coatings used on carpets. and upholstery water resistant clothing grease resistant paper food packaging nonstick cookware cleaning products. personal care products cosmetics paints varnishes and sealants ATSDR 2016 Liu et al 2015 Liu et al 2014 Gewurtz. et al 2009 Guo et al 2009, Once airborne PFAS can occur in a gaseous state or be associated with particulate matter or other aerosols suspended. within the air Neutral volatile precursor compounds such as FTOHs are the dominant PFAS present in the gas phase. and accounted for at least 80 of the total PFAS mass in ambient air in one urban area Ahrens et al 2012 Over the. open oceans and in remote regions FTOHs also dominate neutral PFAS and almost all are present in the gas phase. Bossi Vorkamp and Skov 2016 Lai et al 2016 Wang et al 2015 Dreyer et al 2009 In contrast ionic PFAS such as. PFOA and PFOS characterized by low vapor pressure and high water solubility tend to be the dominant species found. in airborne particulate matter PFOA is associated with smaller ultrafine particles while PFOS is generally associated with. larger coarser fractions in both urban and semirural areas Ge et al 2017 Dreyer et al 2015 Wet and dry deposition are. the major mechanisms of removal of PFAS from the atmosphere and can occur from the scavenging of particle bound. PFAS or partitioning of gaseous PFAS to water droplets Dreyer et al 2010 Barton Kaiser and Russell 2007 Hurley et. al 2004 PFAS are commonly found in rain and snow with wet and dry deposition estimated to occur on a time scale of. a few days Lin et al 2014 Taniyasu et al 2013 Dreyer et al 2010 Kwok et al 2010. Short range atmospheric transport and deposition may result in PFAS contamination in terrestrial and aquatic systems. near points of significant emissions contaminating soil groundwater and other media of concern Davis et al 2007. as well as several miles from industrial emission sources Shin et al 2011 Post Cohn and Cooper 2012 NYS DOH. 2016 NH DES 2017 VT DEC 2016 Releases of ionic PFAS from factories are likely tied to particulate matter Barton. et al 2006 which settle to the ground in dry weather and are also wet scavenged by precipitation Slinn 1984 Sehmel. 1984 Models indicate that deposition depends on amount of PFAS emissions local topography particle size weather. patterns and release characteristics such as smokestack height effluent flowrate and effluent temperature. In addition to short range transport and deposition long range transport processes are responsible for a wide. distribution of PFAS across the earth as evidenced by their occurrence in biota and environmental media in remote. regions as far as the Arctic and Antarctic Long range transport processes and effects are similar to atmospheric. transport of other recalcitrant compounds Prevedouros et al 2006 Benskin et al 2012. Environmental Fate and Transport for,Per and Polyfluoroalkyl Substances continued. Table 4 1 Observed PFAS concentrations in outdoor air. Location Information Concentrations pg m3, Japan Hong Kong and India Ge et Sampling and analysis of ambient PFAS range was about 5 15. al 2017 particles at four sites Ultrafine,particles found to be largest. contributor to mass fraction of,PFCAs while most PFOS mass was in.
the coarse sized fractions Seasonal,differences in PFAS attributed largely. to precipitation, Shenzhen China Liu et al 2015a Air samples collected at 13 sites PFAS concentrations reported as. including industrial areas with mean SD range, many industrial manufacturers port PFHxS 0 31 0 39 ND 1 2. districts as well as less industrialized PFOS 3 1 1 2 ND 4 3. forested and tourist areas Samples PFBA 1 9 1 8 ND 5 0. were analyzed for a range of PFCAs PFPeA 1 9 1 4 ND 4 0. and PFSAs PFHxA 1 5 1 5 ND 3 6,PFHpA 0 042 0 10 ND 0 30. PFOA 5 4 3 8 1 5 15,PFNA 0 49 0 33 ND 1 0,PFDA 0 48 0 38 ND 1 2.
PFUdA 0 018 0 064 ND 0 22,PFDoA 0 20 0 19 ND 0 54,Overall PFAS 15 8 8 3 4 34. Atlantic Ocean from North Atlantic to Measured neutral PFAS in the Total PFAS in air in the gas phase. Antarctic Wang et al 2015a atmosphere across the Atlantic from mean range 23 5 2 8 to 68 8. the North Atlantic to the Antarctic,as well as snow from the Antarctic. Toronto Canada Ahrens et al 2012 Collected samples from a semi FTOHs most abundant PFAS in. urban location while investigating an the gas phase 39 153. improved technique for measuring the FOSAs 0 02 1 1. gas particle partitioning of PFAS using FOSEs 0 33 0 79. an annular diffusion denuder sampler FTACs 0 87 5 9. PFBA dominant PFCA 4 0 22, Parkersburg West Virginia USA Concurrent rain and air samples PFOA predominantly associated with. Barton Kaiser and Russell 2007 collected at nine locations at a particulates and detected as high as. manufacturing facility during a single 1 100,precipitation event and analyzed for. Albany New York USA Kim and Measured PFCAs PFSAs and FTSAs PFAS gas phase 5 10 11 6. Kannan 2007 in air rain snow surface runoff water PFAS particle phase 2 05 6 04. and lake water in an urban area,ND Nondetect,4 2 Soil and Sediment.
PFAS are found in soil and sediment due to atmospheric deposition exposure to impacted media for example landfill. leachate or biosolids and direct discharge Soils and sediments may act as secondary sources of PFAS to groundwater. and surface water through leaching and percolation processes respectively PFAS distribution in soils is complex. reflecting several site specific factors such as total organic carbon TOC particle surface charges and phase interfaces. see Section 3 Properties of individual PFAS such as C F chain length and ionic functional group are also important. factors PFOS PFOA and other long chain PFCAs are typically the predominant PFAS identified in surface sediments. Rankin et al 2016 Strynar et al 2012,Environmental Fate and Transport for. Per and Polyfluoroalkyl Substances continued, Atmospheric transport and deposition of PFAS occur on regional and global scales see Table 4 2 and Section 3 3 and. Section 4 1 PFAA concentrations have been observed across a wide range of locations which suggests that detection. of a PFAA does not always imply a local source, Other environmental sources of PFAS to soil include direct application for example AFFF and industrial discharge or. soil amended with PFAS affected media such as biosolids see Table 4 2 Individual PFAS concentrations may be above. 1 000 ng g 1 mg kg at AFFF sites In comparison to AFFF sites published data on soil PFAS concentrations in industrial. settings are limited Table 4 2 PFAS soil concentrations at industrial sites and sites with applied biosolids or sludge may. be highly variable depending on the nature of PFAS release and proximity to the source. PFAS discharge to surface waters has also affected sediments Few studies have evaluated PFAS association with field. collected sediments Table 4 2 Higher concentrations may be present in certain locations associated with direct PFAS. Table 4 2 Observed PFAS concentrations in soil and sediment. Location Information Concentrations g kg, Global Distribution Rankin Worldwide survey of 62 soils samples PFOA and PFHxA PFCAs 0 029 14 3. et al 2016 detected in all samples and PFOS detected in all but one PFSAs ND 3 27 only. sample PFOS and PFOA the most frequently detected one sample was ND. Remote area Lake Bonney,Antarctica,PFOA 0 048,PFOS 0 007.
Global locations not Evaluated 60 soil samples from six countries and reported Global median. associated with known global median concentrations PFOS detected in 48 concentrations. PFAS sources Strynar et and PFOA detected in 28 of the samples Note that PFOA 0 124. al 2012 concentrations LOQ 0 5 g kg were assigned a value PFOS 0 472. of LOQ 2 for the median calculations, Location near industrial Concentrations of ammonium perflurooctanoate APFO APFO 110 170. PFAS source Davis et al in two soil borings located within an impacted well field. 2007 concentrations decreased rapidly with depth, Fire Training Fire Response PFOS and PFOA in soils at an unlined fire training area Median concentrations. Houtz et al 2013 PFOS 2 400, Fire Training Fire Response In a survey of 40 sites impacted by PFAS the most PFOS. Anderson et al 2016 frequently detected compounds were PFOS 99 of Median 53. surface samples PFHxS 77 and PFOA 79 PFOS Max 9 700. was detected at the highest concentrations, Industrial Areas PFOA and PFOS concentrations in soil were compiled Max. Zareitalabad et al 2013 PFOA 48, Municipal Biosolids Six municipal biosolids and biosolid amended surface Biosolids.
Sepulvado et al 2011 soils PFOS 80 219,MeFOSAA 63 143. EtFOSAA 42 72,Biosolid amended soil,PFOS 2 438, Sediments Lake Ontario Maximum sediment concentrations of PFOA PFOS and 10 s 100 s. Yangtze Mississippi other PFAAs,Rivers Qi et al 2016 Yeung. et al 2013 Oliaei et al,2013 Pan et al 2014,ND Nondetect. LOQ Limit of Quantitation,Environmental Fate and Transport for.
Per and Polyfluoroalkyl Substances continued,4 3 Groundwater. Groundwater represents a potential PFAS exposure pathway by direct ingestion of contaminated drinking water or. indirect ingestion of PFAS in crops irrigated with the contaminated water Groundwater may also discharge to surface. water which can be another PFAS exposure pathway for human and ecological receptors Due to the mobility and. persistence of PFAA in soil and groundwater PFAAs are expected to form larger plumes than other contaminants in. the same hydrogeological setting Sorption and partitioning however may restrict leaching rates from the vadose zone. and reduce the advection driven transport velocity of PFAS in groundwater depending on specific properties of the. compounds These processes may help limit plume development and discharge to surface water and may also provide. time for transformation of PFAA precursors Groundwater geochemistry may dictate the extent of transformation since. nearly all processes identified to date are aerobic Liu and Mejia Avenda o 2013 Groundwater extraction and treatment. for containment or remediation of other contaminants can also influence plume development and distribution of PFAS. in groundwater At sites with remediation systems for other contaminants PFAS impacted water can be unknowingly. reinjected into groundwater as well as discharged to surface water or wastewater treatment plants and create secondary. USEPA generated the most extensive PFAS groundwater occurrence dataset when it required approximately 4 900. public water systems all large systems serving more than 10 000 people plus a subset of smaller systems to monitor. six PFAAs in drinking water at points of entry to the drinking water distribution system The study was conducted. between 2013 and 2015 under the third Unregulated Contaminant Monitoring Rule UCMR3 and included the results. from treated water that largely originated from groundwater wells but also included surface water and mixed sources. A summary of the UCMR3 occurrence data is included in the Regulations Guidance and Advisories fact sheet One or. more PFAS were detected in 4 of the reporting public water systems USEPA 2017b however groundwater sources. had approximately double the detection rate of surface water sources Hu et al 2016 Detections of longer chain. PFAAs were highly associated with groundwater while shorter chain PFAAs such as PFBS and perfluoroheptanoic acid. PFHpA were more associated with surface water Detections were geographically widespread but showed quantifiable. associations with suspected sources including industrial sites military fire training areas AFFF certified airports and. wastewater treatment facilities Hu et al 2016, Groundwater occurrence data collected during several other key studies are summarized Table 4 3. Table 4 3 Observed PFAS concentrations in groundwater. Location Information Concentrations g L, Various New Jersey NJ One or more PFAS detected in 19 of 21 untreated PFOA 0 009 0 057. DEP 2014 groundwater samples from drinking water treatment PFOS 0 005 0 012. plants across the state PFOA was detected in 7 and. PFOS was detected in 5 of the 21 samples, AFFF release sites other Tested 149 groundwater samples most commonly Median Maximum. than fire training areas detected PFAAs PFHxS 95 PFHxA 94 PFOA PFHxS 0 87 290. Anderson et al 2016 90 PFPeA 88 PFBA and PFHpA 85 PFHxA 0 82 120. PFOS 84 The frequency of detections for PFSAs PFOS 4 22 4 300. in groundwater was generally higher than those PFOA 0 405 250. of PFCAs which has been attributed to the use of PFPeA 0 53 66. specific AFFF formulations PFBA 0 18 64,PFHpA 0 235 75.
Fire Training Fire Response Studies at U S military installations and other Maximum. Moody and Field 1999 AFFF release areas have documented relatively PFOA 6 570. Moody et al 2003 Houtz et high detection frequencies of PFAAs in underlying PFOS 2 300. al 2013 groundwater,Environmental Fate and Transport for. Per and Polyfluoroalkyl Substances continued,4 4 Surface Water. Human exposure to PFAS from surface water can occur through direct ingestion or by consuming aquatic biota from. contaminated waterbodies Most PFAAs are acids with low pKa values which means that in the environment they are. most often present in their anionic form deprotonated see Section 6 2 2 of the Naming Conventions and Physical and. Chemical Properties fact sheet Due to the low volatility and low sorption coefficients of these anions much of the. PFAAs that reach surface water tend to remain in solution although there is likely to be partitioning to sediment and. uptake to biota Once in surface water PFAAs can contaminate groundwater through groundwater recharge Liu et al. 2016 ATSDR 2008 or be transported to the oceans where they are then transported globally by ocean currents Benskin. et al 2012 Upon reaching saline waters however the solubility of anionic PFAAs decreases and sorption increases. which likely results in a salting out effect that scavenges some PFAAs especially long chain PFAAs to the sediments. of estuarine environments Hong et al 2013 Despite this oceans are likely the main sink for PFAS and have been. estimated to contain the majority of PFCAs historically released into the environment Armitage et al 2006 In contrast. to PFAAs other PFAS for example FTOHs and some perfluoroalkyl sulfonamides remain neutral at environmentally. relevant pHs have higher volatilities and tend to partition into air PFAS composition may also change within surface. water because of biotic and abiotic degradation of PFAA precursors as described in Section 3 3. Freshwater marine water and stormwater PFAS concentrations usually depend on proximity to releases In addition to. releases associated with identified sources stormwater runoff water from nonpoint sources may contribute significant. loads of PFAS to surface water Wilkinson et al 2017 Zushi and Masunaga 2009 Table 4 4 shows some typical. PFOS and PFOA environmental concentrations organized by source type In addition to PFOS and PFOA many. other PFAS have been observed in surface waters including compounds other than PFAAs For example perfluoro 2. propoxypropanoic acid PFPrOPrA has been measured in the Cape Fear River in North Carolina at concentrations up to. 4560 ng L Sun et al 2016, Table 4 4 Observed PFAS concentrations in surface water. Location Information Concentrations ng L,Freshwater. Remote Areas Filipovic et al 2015 PFOS and PFOA concentrations in 100s of pg L. Eriksson et al 2013 Stock et al 2007 the Faroe Islands and remote areas Single ng L. of Sweden have been measured in,the 100s of picograms per liter range.
while concentrations in the Canadian,Arctic have been measured in the single. nanogram per liter range, Industrial Areas Japan and PFOS concentrations can be as high as Maximums. Tennessee River USA Saito et al 144 ng L PFOA concentrations can be as PFOS 144. 2004 Hansen et al 2002 high as 67 000 ng L PFOA 67 000. Fire Training Fire Response Saito et AFFF impacted surface water can have Maximums. al 2004 Anderson et al 2016 PFOS concentrations reaching 8970 ng L PFOS 8 970. and PFOA concentrations reaching 3750 PFOA 3 750, Municipal Wastewater Treatment PFOS and PFOA reported in surface Maximums near typical WWTPs. Facilities waters near municipal WWTP outfalls PFOS 24. Becker Gertsmann and Frank 2008 with higher 4x concentrations reported PFOA 25. Boulanger et al 2005 Wilkinson et al for surface water near outfalls of WWTP Maximum near WWTP affected. 2017 MDH 2008 impacted by chrome plating wastewater by chrome plating waste. Marine Water, Open Water Benskin et al 2012 Cai PFAA concentrations in open waters tend pg L. et al 2012a Zhao et al 2012 to be on the order of picograms per liter. Coastal Areas Benskin et al 2012 In heavily populated coastal areas PFAA ng L. Cai et al 2012a Zhao et al 2012 concentrations can be on the order of a. few nanograms per liter,Environmental Fate and Transport for.
Per and Polyfluoroalkyl Substances continued,Location Information Concentrations ng L. Stormwater, Residential Undeveloped PFAS concentrations measured in Maximums. Xiao Simick and Gulliver 2012 residential campus and field settings PFOS 15 5. Wilkinson et al 2016 Zhao et al in Minnesota China and England PFOA 19 1. 2013b respectively PFHxA 4,PFHpA 22 5, Commercial heavy traffic PFOS and PFOA measured in storm water Range. Minneapolis St Paul MN eastern runoff from streets in areas not related to PFOS LOQ 590. and central China cities and England specific releases but unidentified local or PFOA 3 5 1 160. Xiao Simick and Gulliver 2012 Zhao consumer sources may be responsible for PFHpA ND 6 8. et al 2013b Wilkinson et al 2016 higher concentrations detected PFNA ND 648. PFDA ND 10 6,PFUnDA ND 2 9, Industrial Areas Minneapolis and St PFOS measured in stormwater in an Range. Paul MN Xiao Simick and Gulliver industrial area with suspected PFAS PFOS 8 7 156. Airport Ditch likely impacted by AFFF PFAAs measured predominately PFHxS Total PFAAs 6 42 804. Korea Kim et al 2014 and PFOS,4 5 Biota and Bioaccumulation.
PFAS occur widely in biota specifically in plants invertebrates fish and humans through bioaccumulation processes. PFAAs particularly PFOS are typically the dominant PFAS detected in biota Houde et al 2011 PFAA concentrations in. biota are influenced by uptake and elimination of both PFAAs and their precursors as well as biotransformation rates of. PFAA precursors see Section 3 3 2 Asher et al 2012 Gebbink Bignert and Berger 2016 Therefore concentrations of. PFAAs observed in biota at one location may not reflect concentrations in other environmental media. 4 5 1 Plants, Studies show evidence of uptake and accumulation PFAAs by plants in several settings and applications including both. controlled experiments and field investigations Concerns about introducing PFAAs into livestock or crops have led to. investigations of uptake and accumulation in plants Uptake mechanisms and the extent to which native plant species. remove and accumulate PFAS have not been as well studied. PFAS may be introduced to plants from soil water or air by. irrigation water, the application of biosolids or sludge amended soils. soil and groundwater at PFAS sites or near releases of PFAS. exposure through contact with rainwater and atmospheric deposition. Studies demonstrating plant uptake of PFAAs have focused on irrigated crops Stahl et al 2009 Scher et al 2018 crops. in biosolids amended soil Yoo et al 2011 Blaine et al 2013 2014 and aquatic plants in constructed wetlands Chen. Lo and Lee 2012 Other investigations have focused on flora exposed to PFAAs in the natural environment Zhang et. al 2015a or near known PFAS sources Shan et al 2014 Plant uptake and bioaccumulation and partitioning within the. plant appear to depend on PFAS chemical structure and the plant species Most studies report partitioning of PFAAs. within plants with longer chain PFAAs especially PFSAs partitioning to the roots and more soluble shorter chain. PFAAs especially PFCAs partitioning to other parts of the plant Lechner and Knapp 2011 Stahl et al 2009 Blaine et. al 2013 2014 Yoo et al 2011 Scher et al 2018 Gobelius Lewis and Ahrens 207 The behavior of other PFAS such as. PFAA precursors is currently the topic of ongoing research. Environmental Fate and Transport for,Per and Polyfluoroalkyl Substances continued. 4 5 2 Invertebrates, Invertebrates act as the main component of the food web base and play a key role in the dynamics of biomagnification. Aquatic invertebrates can reside in the water column as well as on or in the sediment substrate In higher trophic. level organisms PFOS has been documented as the dominant PFAS with concentrations increasing up the food chain. while PFOA has a lower bioaccumulation potential and concentrations are similar among species of different trophic. level animals Houde et al 2011 Conder et al 2008 In invertebrates both PFOS and PFOA have maximum values. within similar ranges Ahrens and Bundschuh 2014 Studies present a PFAS range of approximately 0 1 to 10 g kg in. invertebrate tissue although their sources predominantly address marine organisms Houde et al 2011 Similar levels. of PFOS have been found in freshwater invertebrates 2 to 4 3 g kg and with a bioconcentration factor BCF biota. water estimated at 1 000 L kg Kannan et al 2005 Concentrations of PFOS PFCAs and heptadecafluorooctane. sulfonamide PFOSA have been observed in Lake Ontario invertebrates ranging from 0 5 to 280 g kg Martin et al. 2004 The concentrations in invertebrates were higher than in fish from this lake. In terrestrial systems current research indicates bioaccumulation potential of PFOS is low as is biomagnification. increasing concentrations in predators over their prey from lower to higher trophic level organisms CEPA 2017 In. biosolid amended soils PFAS bioaccumulation factors BAFs in earthworms have ranged from 2 2 to 198 g dw soil g dw. worm Navarro et al 2016 Maximum BAFs in earthworms for all PFAS types have been observed at 45 g dw soil g dw. worm for biosolids amended soils and 140 g dw soil g dw worm for soils contaminated with AFFF Rich et al 2015. 4 5 3 Fish, Accumulation of PFAS in fish has been documented particularly for PFOS longer chain PFCAs with eight or more.
carbons and perfluorodecane sulfonate PFDS Houde et al 2011 Martin et al 2013 Conder et al 2008 Of the. PFAS PFOS generally has the highest concentrations in fish due to the historically high use of this chemical and its. bioaccumulation potential Houde et al 2011 PFDS long chain PFCAs and other PFAS have also been measured in. fish Houde et al 2011 Fakouri Baygi et al 2016 Shorter chain PFCAs and PFSAs less than eight and six carbons. respectively are not readily bioconcentrated or accumulated Conder et al 2008 Martin et al 2013 Houde et al 2011. but as perfluoroalkyl chain length increases PFSAs are generally more bioaccumulative than PFCAs with the same. number of carbons in the chain, In fish PFOS tends to partition to the tissue of highest protein density including the liver blood serum and kidney Falk. et al 2015 Ng and Hungerb hler 2013 This distribution pattern is contrary to other persistent chemicals which tend to. partition to adipose tissue, Due to the difficulty of measuring octanol water partitioning coefficients Kow for PFAS BAFs rely on calculations from. empirical data instead of modeling Hauk s et al 2007 For PFOS bioconcentration from water is the predominant route. of accumulation in fish Martin et al 2003a b Giesy et al 2010 with dietary concentrations playing a reduced role in. accumulation In Michigan concentrations of PFOS were found to be 10 to 20 times greater in predator fish than in their. prey species Kannan et al 2005 PFOS appears to be the predominant PFAS concentrated from water with BAFs in. field based studies ranging from approximately 550 to 26 000 L kg Naile et al 2013 Lanza et al 2017 Ahrens et al. 2015 Giesy et al 2010 in whole fish, Biomagnification and trophic transfer of PFAS in fish have been shown in some food webs Franklin 2016 Fang et al. 2014 Because PFAS partition into proteins rather than lipids however the degree of observed biomagnification and. trophic transfer in the field may be related to the quantity and composition of protein in the tissue measured as well as. the capability of the fish for metabolic biotransformation of PFAA precursors Butt et al 2010 Asher et al 2012 Gebbink. Bignert and Berger 2016, Fish occurrence data collected during several other key studies are summarized in Table 4 5.

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