introduction to pfas - astswmo

Introduction To PFAS

ASTSWMO

Milwaukee, WI

August 14, 2019

Topics for Plenary Session

Topic

Intro to ITRC

PFAS Background:

• PFAS Sources & Naming Conventions

• Basic Chemical & Physical Properties

Toxicity, Risk Assessment, & Regulations/Guidance Values

Fate & Transport

Treatment Technologies

Q&A

2

What is ITRC?

▪ ITRC is a state-led coalition working to advance the use of innovative environmental technologies and approaches. ITRC’s work translates good science into better decision making.

3

ITRC PFAS Team

▪ 500+ PFAS experts from all sectors: academics,

stakeholders; state and local; federal; industry and

consulting

▪ Producing concise technical resources for project

managers – regulators, consultants, responsible parties,

and stakeholders

▪ Why: State and federal environmental regulators and

others need easily accessible information to aid them in

evaluating risks and selecting appropriate response

actions at PFAS release sites

4

ITRC PFAS Team Products◆ Factsheets

• History and Use (Nov. 2017)

• Naming Conventions & Physical and Chemical Properties (March 2018)

• Regulations, Guidance, and Advisories (January 2018)

• Fate & Transport (March 2018)

• Site Characterization, Sampling Techniques, and Lab Analytical Methods (March 2018)

• Remediation Technologies (March 2018)

• AFFF (October 2018)

◆ Web-based, updated information tables

◆ Online training modules in early 2020

◆ Publication of the Risk Communication Toolkit in early 2020

◆ Publication of the web-based Technical and Regulatory Document early 2020

5

https://pfas-1.itrcweb.org

PFAS Background

What Are Per- and Polyfluoroalkyl Substances (PFAS)?

▪ Large class of surfactants (>4000) with unique chemical & physical properties that make many of them extremely persistent and mobile in the environment

▪ Used since 1940s in wide range of consumer & industrial applications

7

Source: open access images – bing.com

PFAS Major Sources

8

Fire Training/Fire Response Sites

Industrial Sites

Landfills*

WWTPs/Biosolids*

*PFAS concentrations vary widely depending on the waste stream –not all landfills or WWTPs are major sources

LEACHATEBIOSOLIDS

The General Classes of Per- and

Polyfluoroalkyl Substances (PFAS)

9

Perfluoroalkyl acids:• Carboxylates• Sulfonates

Fluorotelomers:• Sulfonates• Carboxylates• Alcohols

Source: ITRC Naming Conventions and Physical

Chemical Properties fact sheet

• Fluoropolymers• Perfluoropolyethers (PFPE)• Side-chain fluorinated

polymers

?

Basic PFAA Structure

▪ Perfluoroalkyl Acids (PFAAs)

◆ Fully fluorinated chain (2 or more carbon or alkane “tail”)

◆ Functional group (“head”)

• PFCAs: Carboxylate group (COO-)

• PFSAs: Sulfonate group (SO3-)

10Source: ITRC Naming Conventions and Physical


Source: open access

image from bing.com

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiH16bo8v_YAhUW82MKHV04DkgQjRwIBw&url=https://www.fcm.fraunhofer.de/en/beispiele11/perfluorierte_tensideinlebensmitteln.html&psig=AOvVaw0Q8p9wSSh2thdvwyogOBX2&ust=1517408888327770

PFAA Naming System

▪ PFXY

◆ PF = perfluoro

◆ X = number of carbons

• Same convention as hydrocarbons

• Includes C in the carboxylate group

◆ Y = functional group

• S = sulfonate

• A = carboxylate

▪ Example:

◆ X: 8 carbons = “octa”

◆ Y: S = sulfonate

11

Perfluorooctane sulfonate (PFOS)

PFAA Naming System



Polyfluoroalkyl Substances

▪ Partially fluorinated

▪ Non-fluorine atom (usually H or O) attached to at least one, but not all, of the carbons in the alkane chain

▪ Creates a “weak link” susceptible to biotic or abiotic degradation

▪ Often named using a “n:x” prefix• n = number of fully fluorinated carbons

• x = number of non-fully fluorinated carbons

13

Replacement Chemistry▪ Short chain PFAS chemistries do not degrade to longer PFAAs

▪ New applications, but not necessarily new chemicals◆ HFPO-DA (Hexafluoropropylene oxide dimer acid), a component of GenX processing

aid technology (Shoemaker and Tettenhorst 2018)

◆ used for decades in fluoropolymer production

▪ For most replacement chemistries, limited information on toxicities, properties, fate and transport, and treatment options◆ USEPA released a draft toxicity assessment for GenX chemicals in November 2018



HFPO-DA (GenX)

PFAS Chemical & Physical Properties

Highlights of PFAS Properties

▪ C-F is the shortest and strongest bond in

chemistry

◆ Small, highly electronegative fluorine atoms

“shield” the carbon from chemical reactions

◆ No biotic or abiotic degradation of PFAA under

natural conditions

◆ PFAAs thermally degrade only at high temperatures

▪ The anion of the perfluoroalkyl acids (PFAAs) are negatively charged

◆ Interact and sorb on positively charged minerals

◆ Mediated by pH, chain length, and functional group

16

kJ/mol of

bonds

C-F 485

C-H 436

C-C 346

C-Cl 339

C-N 305

C-Br 285

C-S 272

High C-F Bond Energy



▪ Chain length and functional group generally determine bioaccumulation

◆ Longer chain and sulfonates tend to accumulate more than shorter

chain and carboxylates

◆ PFHxS breaks this “rule” – longer half-life in humans than PFOS

◆ Some PFAS are “proteinphiles”, so bioaccumulation process may be

more complicated than for other environmental contaminants.

▪ Surfactant properties are important

◆ Partitioning to interfaces (air-water, soil-water, NAPL-water) and

micelles

◆ PFAAs can be both hydrophobic and hydrophilic

17


▪ PFAAs may be linear or branched in form

◆ May affect partitioning and/or bioaccumulation - not well understood yet

▪ PFAAs generally have low volatility, however…

◆ Air transport may occur for PFAAs sorbed to particulates or dissolved in

water droplets

◆ PFAAs may be formed from volatile precursors (e.g., FTOHs)



Toxicity, Risk Assessment, and Regulations

Health Effects of PFOA and PFOS

* PFOA Only

20

▪ Animal

◆ Liver effects

◆ Immunological effects

◆ Developmental effects

◆ Endocrine effects (thyroid)

◆ Reproductive effects

◆ Tumors (liver, testicular*, pancreatic*)

▪ Human (possible links)

◆ Liver effects (serum enzymes/bilirubin, cholesterol)

◆ Immunological effects (decreased vaccination response, asthma)

◆ Developmental effects (birth weight)

◆ Endocrine effects (thyroid disease)

◆ Reproductive effects (decreased fertility)

◆ Cardiovascular effects (pregnancy induced hypertension)

◆ Cancer* (testicular, kidney)

Toxicology of PFOA and PFOS

▪ Most toxicology studies have focused on PFOA and PFOS

▪ Non-cancer effects in mammals are primarly focused on developmental effects

▪ Immunotoxicity potential

▪ Potential carcinogenic properties ◆ “Suggestive” for both (USEPA) and “Possibly” for PFOA (International

Agency for Research on Cancer)

◆ Cancer Slope Factor (CSF) for PFOA: 0.07 (mg/kg*day)-1

• Risk-based drinking water threshold for cancer endpoint higher (less conservative) than non-cancer endpoint

21

Factors Impacting Numerical Value of PFAS Drinking Water Guidelines

22

Factor Explanation Examples Impact

Reference Dose

(POD ÷ Total UF; also includes

animal-to-human

extrapolation factor)

Point of Departure (POD): • NOAEL• LOAEL• Benchmark Dose

(BMDL)

Dose (mg/kg/day) from animal study used as starting point

• LOAEL for ↓ offspring body weight in rats

• NOAEL for ↓ immune response in mice.

↑ POD → ↑ Guideline

Uncertainty factors (UFs)

• POD is divided by individual UFs of 1-10

• Total UF generally 30-300

• Interindividual• Animal-to-human• Data gaps

↑ Total UF→

↓ Guideline

Animal-to-human doseextrapolation

To account for higher internal levels in humans than lab animals from same dose

• Serum PFAS levels as dose metric

• Human-to-animal half-life ratio

Depends on specifics of approach.

Exposure

Drinking water consumption rate

• L/kg/day.• Based on daily ingestion

(L/day) and body wt. (kg)

Infant > Lactating Woman > Default Adult

↑ Ingestion rate →

↓ Guideline

Relative Source Contribution (RSC)

Accounts for non-drinking water exposure sources (e.g. food, air).

• Default - 20%• Up to 80% based on

chemical-specific data.

↑ RSC → ↑ Guideline

Drinking Water Guideline = Reference Dose (mg/kg/day) x Relative Source Contribution (%)Drinking Water Consumption Rate (L/kg/day)

Note: For Canadian practitioners, refer to HC and ECCC regulations and guidance. More at Stream 3A, 1:30 to 3 pm today!

Toxicology of Other PFAS▪ Information for some PFAS in peer-reviewed literature and

chemical registration information (REACH dossiers, TSCA submittals)

▪ Most focused on the PFCAs and PFSAs, the perfluoroalkyl acid “families” to which PFOA and PFOS belong

▪ Effects generally similar (developmental, liver, kidney, etc.)◆ Long-chain PFAAs appear to have effects generally similar in animal studies

(developmental, immune, liver, etc.)

◆ Animal data for short-chain PFAAs show liver and kidney effects at high concentrations

▪ USEPA IRIS announced in December 2018 five PFAS will be reviewed for toxicity assessment (PFNA, PFBA, PFHxA, PFHxS, PFDA), no timeline given

23

24

Risk Assessment

ITRC 2015. Decision Making at Contaminated Sites: Issues and Options in Human Health Risk Assessment.

Risk Assessment Challenges

▪ It’s not just PFOA and PFOS◆ 16 other PFAS by USEPA Method 537 (Nov. 2018)

◆ Additional 10-15 more PFAS via other methods

◆ Dozens to hundreds of other PFAS in AFFF

25


26

▪ Toxicity information◆ Room for improvement with existing PFOA and PFOS

toxicity values and cancer assessments

◆ Additivity of PFOA and PFOS

◆ Other PFAS? Toxicity higher or lower?

Source: Geosyntec


▪ Background/ambient issues◆ How to manage non-site related PFAS from watershed or

aquifer sources?

◆ Background exposures for humans

◆ Relative source contribution (0.2) in EPA Lifetime Health Advisory for Drinking Water

◆ Assumes human receptor can receive only 20% of a reference dose from specific exposures (e.g., site-specific exposures must be 5X below reference dose)

27


▪ No standard guidance or models for risk assessment (conceptual site models, sampling approaches, uptake factors, toxicity values) …yet

▪ Health Canada has published a framework for Canadian federal sites (Human Health Risk Assessment Framework for Federal Sites Impacted with PFAS)

▪ Where to focus assessment and management?◆ Groundwater, surface water, sediment, soil, diet?

28

PFAS Regulatory Drivers▪ EPA Drinking Water LHA for PFOA and PFOS not enforceable standards

▪ CERCLA and RCRA◆ PFAS not yet CERCLA hazardous substances, so no cost recovery for Superfund

(although they are considered a pollutant or contaminant and can be investigated)

▪ Others◆ Site investigations and management driven by other forces, including: voluntary

action (regulatory and public perception pressure), litigation, Clean Water Act (TMDL), variable approaches at state-level

▪ Available guidelines for PFOA and PFOS may be used as regulatory drivers, but that may not be sufficient to justify federal expenditures

▪ Consult legal counsel – PFAS regulatory landscape will continue to evolve

▪ Consult your local regulatory agency

29

Regulatory Approaches▪ EPA 2009 Provisional Short-term Health Advisories have been replaced

by 2016 Lifetime Health Advisories (LHAs)▪ Many states with a variety of regulatory approaches, focusing primarily

on PFOA and PFOS◆ 19 states have criteria in water ◆ 6 states have drinking water values that are different from EPA’s LHAs

▪ Variety of state approaches for other PFAS (6 have criteria for other PFAS)◆ Texas Commission on Environmental Quality (TCEQ) 14 PFAS besides PFOA and PFOS◆ California: PFOA and PFOS listed on Prop 65 (November 2017), PFAS-containing

carpet and rugs proposed as “Priority Product” (evaluate use or ban in commerce, February 2018)

▪ Approaches and values are changing rapidly▪ Visit ITRC for the latest compilation: https://pfas-1.itrcweb.org/▪ Consult your local regulatory agency

3030

https://pfas-1.itrcweb.org/

Figure by W. DiGuiseppi, Jacobs - used with

permission. Data current as of June 2019

0.07 0.07

0.07 0.07

24

300

0.29

0.56

0.035

2

0.07 0.07

0.02 0.02

PFOA

PFOS

0.070.07

0.070.07

0.070.07

0.070.07

0.070.07

0.667

0.667

0.070.07

0.2

Canada

0.6

0.07

0.56

Australia

0.070.07

0.014 0.013

0.015

NOT TO SCALE

0.009 0.008

0.01

Guidelines and Standards (µg/L)PFOA, PFOS

31

0.07 0.07

0.01

States with Values for Other PFAS(and year implemented)

20162016

2018

2017

2007

2015

2011MA: Sum of 5 PFAS <0.07 µg/L (June 2018)

32

2018

Figure by W. DiGuiseppi, Jacobs - used with permission

MN: “TEQ-like” additivity for 5 PFAS

VT: Sum of 5 PFAS <0.02 µg/L (2018)

Representative Residential Soil

Screening Levels

0.0017

0.0095

0.35

0.017

0.0015

0.000172

1.3

16

1.2

1.7

60.33

1.56

0.50.5

1.26

0.003

0.021

0.00022

0.0015

0.000378

1.3

61.8

1.7

3.21.7

1.560.5

1.5

1.26

0 5 10 15 20

AK (2017) (Migration to GW)ME (2018) (Migration to GW)MI (2016) (Migration to GW)NC (2016) (Migration to GW)

TX 30-acre source (2017) (Migration to GW)USEPA RSL (2018) (Migration to GW)

AK (2017)DE (2016)IA (2016)

ME (2018)MI (2016)

MN (2016)NV (2017)NH (2017)

TX (2017) 30-acre sourceEPA RSL (2018)

PFOS PFOA

Guidance and Screening Levels – Soil (mg/kg)

Health Canada (2017) 2.10.85

Protective of Human Direct Contact

Protection of Drinking water

Australia (2018)0.009

0.1

Figure by W. DiGuiseppi, Jacobs - used with permission

Data current as of March 201933

Risk Communication Principles for PFAS 1. Establish trust by supporting dialogues between the

decision-makers and the affected stakeholders early and continue them through to resolution.

2. Include the community in the decision-making process.

3. Present information clearly and make it accessible to stakeholders.

4. Address uncertainties head on, be clear and transparent about knowns and unknowns.

5. Listen, acknowledge, and follow up with specific concerns.

6. Develop a context for the risk that will help audiences evaluate how to respond to risk.

34

Open access image

NJDEP 1991. “Improving Dialogues with Communities: A Risk communication Manual for Government.” by Billie Jo Hance, Caron Chess and Peter M. Sandman. New Jersey Department of Environmental Protection.

Human Exposure Pathways

▪ Major1,2

◆ Diet (bioaccumulation)• Fish and seafood• Produce

◆ Drinking water

◆ Incidental soil/dust ingestion

▪ Usually insignificant or minor◆ Dermal absorption

◆ Inhalation

35

1 Oliaei et al., 2013. Environ. Sci. Pollut. Res. Manag. 20:1977-19922 Domingo, 2012. Environment International 40:187-195 Source: Open source, Pixabay

ITRC PFAS Risk Communication Toolkit

• Message Mapping Guide

• PFAS-specific Key Messages

▪ Fact Sheets & FAQs Compilation

▪ Guidance for Writing Analytical Results Summary Letters

▪ Guidance for Writing Press Releases

▪ Social Factors Vision Board

• Actor Mapping Tools• Agenda for First Internal Communication Team Planning Meeting

• PFAS-specific SMART Goals

Steps 1 & 2 Identify the

Issue & Set Goals

Steps 3 & 4 Audience

Assessment:

Steps 5 Identify

Messages

Step 6 Communication

Methods

36

ITRC Draft material

Fate and Transport

PFAS Characteristics

Site Characteristics

38

PFAS

Fate & Transport

38

PFAA Sorption and Transport

Analyte # Carbons Koc1 Rf

PFBA 4 76 5

PFPeA 5 23 1.4

PFHxA 6 20 1.1

PFHpA 7 43 3

PFOA 8 78 5

PFNA 9 229 14

PFDA 10 912 57

PFUnA 11 3,600 225

PFBS 4 62 4

PFHxS 6 112 7

PFOS 8 631 39

▪ Sorption (Koc and Kd) (generally) increases with # of carbons

▪ Short-chain PFCAs have greater Koc

than expected

▪ GENERALLY:

◆ Solubility• PFCAs > PFSAs• Short chain > long chain

◆ Sorption• PFSAs > PFCAs• Long chain > short chain

◆ Relative partitioning• Soil, sediment, animals: PFSAs• Water, plants: PFCAs

1 Koc data from Guelfo, J.L., Higgins, C.P. Subsurface transport potential of perfluoroalkyl acids at aqueous film-forming foam (AFFF)-impacted sites. Environ. Sci. Technol. 2013. 47, 4164–4171.

39

Other factors impacting PFAA Transport

▪ Increased retardation (sorption)◆ Lower pH (more acidic)1,2

◆ Greater polyvalent cations1,2 (Ca2+, Fe3+, etc.)

◆ Presence of non-aqueous phase liquids3,4

▪ Retardation impacted by remedial approaches that change pH or introduces polyvalent cations (i.e., ISCO)2,4

1 Higgins and Luthy, 2006. ES&T; 2McKenzie et al., 2015 ES&T ; 3Guelfo and Higgins, 2013. ES&T; 4McKenzie et al., 2016. Water Research

Reprinted with permission from McKenzie et al. 2015. Effects of Chemical Oxidants on Perfluoroalkyl Acid Transport in One-Dimensional Porous Media Columns. Env. Sci. & Tech., 49:1681-1689. Copyright 2015 American Chemical Society.

40

Transformation of PFAA Precursors

O

F S

F

F

F

F O

N O

O7

N-EtFOSEpolymer

O

F C

F

F

F

F O-

F

F

F

F

F

H

H

H

H

OH

F

F

F

F

F

H

H

H

H

OO

F

F

F

F

F

H

H

O-

O

7

7

7

O

F C

F

F

F

F O-6 7

PFOA PFNA

8:2 FTOHpolymer

8:2 FTOH

8:2 FTCA

O

F S

F

F

F

F O

O-

O

F S

F

F

F

F O

N

O

O-

O

F S

F

F

F

F O

N OH

O

F S

F

F

F

F O

NH2

7

7

7

7

FOSA

PFOS

N-EtFOSE

N-EtFOSAA

Figure courtesy of C. Higgins

41

Complexity Varies with Time, Space, and History

Old Distal Significant

RecentSourceZone None

Source: Adapted from figure by L. Trozzolo, TRC, used with permission 42

Water Treatment

▪ Effective conventional approaches, with limitations:◆ Carbon adsorption

◆ Resin adsorption

◆ Reverse osmosis

▪ Typically ineffective conventional technologies:◆ Air stripping, air sparging

▪ Technologies in development:◆ Examples include - bioremediation, chemical oxidation,

chemical reduction, thermal desorption, electrochemical,

others

▪ Be aware of precursor transformations via

treatment processes, particularly with oxidation

and biodegradation

44

Image courtesy of MN Dept. of Health

Soil Remediation Technologies

▪ Conventional◆ Excavation and landfill

◆ Excavation and offsite incineration

◆ Stabilization

▪ Developing/Limited demonstrations◆ Soil Washing

◆ Thermal

45

Photo courtesy of CH2M/Jacobs

Questions?

Ginny Yingling, Minnesota Dept. of Health651-201-4930

[email protected]

PFAS: Nuts & Bolts for Site Managers

ASTSWMOMilwaukee, WIAugust 14, 2019

ITRC PFAS Workshop AgendaPresenter Topic

Ginny Yingling, MDH History & Sources

Physical & Chemical Properties

Fate & Transport (incl. case study)

Stretch break

Shalene Thomas, Wood Site Characterization

Sampling & Analysis


Q&A

49

PFAS History & SourcesGinny Yingling, MN Dept. of Health

A Brief History of PFAS▪ Two major production processes:

◆ Electrochemical Fluorination (ECF) approx. 70% linear and 30%

branched PFAS

◆ Fluorotelomerization mainly even numbered, linear PFAS

51Source: ITRC History and Use fact sheet

Phase-Out of Long-Chain PFAS▪ Potential health and environmental concerns, particularly for more

bioaccumulative “long-chain” PFAS

▪ 2002-2008: 3M voluntarily phased out production of PFOS, PFHxS, PFOA, and related precursors

▪ 2010-2015: U.S. manufacturers eliminated production of PFOA and longer-chain PFCAs

▪ Exemptions: USEPA SNURs allow continued, low-volume use in specific applications (semiconductor, etching, metal plating, aviation, and photographic/imaging)

▪ Production shifted to parts of Asia and Eastern Europe



Major Sources of PFAS

53

Aqueous Film Forming Foam (AFFF)▪ Military installations & civil airports▪ Petroleum Refineries & Chemical Facilities▪ Fire Fighting Training Areas

Industrial (primary production & secondary manufacturing )▪ Surfactants, resins, molds, plastics▪ Plating and etching (esp. chrome)▪ Coatings (textiles, leather, paper, photographic, etc.)

Landfills▪ Consumer products, industrial waste, demolition debris▪ Biosolids from WWTP applied as cover

Waste Water Treatment Plants▪ PFAS in influent (from industrial & residential sources) may not be treated

and end up in effluent▪ Biosolids created in treatment process may contain PFAS

Source: open access images –

bing.com

CSM for AFFF Application Sites

54Source: ITRC Environmental Fate and Transport fact sheet,

Figure Adapted from figure by L. Trozzolo, TRC, used with permission

CSM for Industrial Sites



All pathways, plus air

CSM for Landfills and WWTPs



PFAS Chemical & Physical PropertiesGinny Yingling, MN Dept. of Health


▪ C-F is the shortest and strongest bond in

chemistry

◆ Small, highly electronegative fluorine atoms

“shield” the carbon from chemical reactions

◆ No biotic or abiotic degradation of PFAA under

natural conditions

◆ PFAAs thermally degrade only at high temperatures

▪ The anion of the perfluoroalkyl acids (PFAAs) are negatively charged

◆ Interact and sorb on positively charged minerals

◆ Mediated by pH, chain length, and functional group

59

kJ/mol of

bonds

C-F 485

C-H 436

C-C 346

C-Cl 339

C-N 305

C-Br 285

C-S 272

High C-F Bond Energy



▪ Chain length and functional group generally determine bioaccumulation

◆ Longer chain and sulfonates tend to accumulate more than shorter

chain and carboxylates

◆ PFHxS breaks this “rule” – longer half-life in humans than PFOS

◆ Some PFAS are “proteinphiles”, so bioaccumulation process may be

more complicated than for other environmental contaminants.

▪ Surfactant properties are important

◆ Partitioning to interfaces (air-water, soil-water, NAPL-water) and

micelles

◆ PFAAs can be both hydrophobic and hydrophilic

60


▪ PFAAs may be linear or branched in form

◆ May affect partitioning and/or bioaccumulation - not well understood yet

▪ PFAAs generally have low volatility, however…

◆ Air transport may occur for PFAAs sorbed to particulates or dissolved in

water droplets

◆ PFAAs may be formed from volatile precursors (e.g., FTOHs)



Chemical and Physical Properties

Control Environmental Distribution

62

Tm = melting pt.

Tb = boiling pt.

pKa = acid dissociation

constant

p = vapor pressure

S = solubility

H = Henry’s law constant

Kd = soil/sed partitioning

coefficient

Koc = organic carbon

partitioning

coefficient

BAF = bioaccumulation

factor

BSAF = biota-sediment

accumulation factor

Source: ITRC Naming Conventions and Physical


PFAA Naming System



Wait…Which PFAA Are We Talking About?

▪ Acid or Anion?◆ PFAS may exists in many ionic states (acids, anions, cations, zwitterions)

◆ In the environment, PFAAs exist in the anionic state (sulfonate, carboxylate, etc.)

◆ Acid form of the name often used interchangeably (sulfonic acid and carboxylic acid)

◆ Different CAS numbers & very different chemical and physical properties

▪ What Is My Lab Really Testing For?◆ Some labs report some or all of their PFAAs in the acid form

◆ Depends on the standards used, which may be acids or salts of PFAAs (typically Na+ or K+)

◆ The lab performs a calculation to account for the mass of the cation

• For H+ in acids, this is essentially irrelevant in terms of the results

• For salts, confirm the lab is accurately accounting for the cation mass (Section 7.2.3 of EPA Method 537)

64

Published Physical & Chemical Values

▪ Most values reported in the literature are for PFAA acids

◆ PFAA acids not typically present in environment except at pH <3

◆ Behavior of acids and anions are often VERY different

• PFOA acid: low solubility, volatile / PFOA anion: highly soluble, non-volatile



Sw = solubility in water Koc = org. carbon partition coefficient Y = data available

Po = vapor pressure BAF = bioaccumulation factor N = no data available

Kh = Henry’s Law constant BCF = bioconcentration factor M = data may be available

Kow = octanol/water partition coefficient E = estimated

PFAA Precursors▪ Some PFAS can degrade to PFAAs

◆ Referred to as “PFAA precursors”

◆ Resulting PFAAs sometimes referred to as “terminal PFAAs”

▪ Perfluoroalkane sulfonamides (FASAs)◆ May degrade to PFSAs

▪ Polyfluoroalkyl Substances ◆ Fluorotelomers

• Fluorotelomer alcohols (FTOH)

• Fluorotelomer sulfonates (FTSA)

• Fluorotelomer carboxylates (FTCA)

• May degrade to PFCAs or PFSAs

◆ Perfluoroalkyl sulfonamido ethanols (FASE) & acetic acids (FASAA)

• May degrade to PFCAs or PFSAs

66

As we learn more about transformation pathways, maybe able to use that informationfor site characterization – to determine sources, age, history, etc.

Fate and TransportGinny Yingling, MN Dept. of Health

What is Fate and Transport?

▪ Fate and Transport describes the behavior of PFAS following their release to the environment and encompasses physical, chemical, and biological processes that influence distribution, chemical transformation, and migration

▪ Questions this helps address:◆ What is the potential for exposure from a PFAS release?

◆ Where do I need to look for PFAS following a release?

◆ How can I treat PFAS?

68

Perfluorooctane

sulfonate (PFOS)

C8F17SO3-

Perfluorinated

“tail”Anionic

“Head” group

S

O

O

F O -

F

F

F

F

F

F

F

F

F

F

F

F F

F

F

F

Good news: C-F bond is one of the strongest chemical bonds known

Bad news: C-F bond is one of the strongest chemical bonds known

PFAAs are

extremely persistent

in the environment

Air

Water

PFOS

Images used with permission from Jennifer Field, Oregon State University

69

The Heads and Tails of PFAS

Lipo- & hydrophobic tail

Wang et al. 2017, ES&T.

PFAS Family Tree: It’s not just PFOS and PFOA

Barzen-Hanson et al., 2017, ES&T.

Total PFAS high resolution mass spectrometry (HRMS) suspect list now ~1500 compounds

– HRMS library now includes ~325 PFAS

– ~120 homologous series: - (CF2)n - where n = 1 to 18

• 14 classes are truly perfluorinated (all C-H are C-F)

• ~50 classes are ECF-derived, while ~70 are FT-derived

– To date, most sites have ~10 to 100 different PFAS

Reprinted with permission from Wang et al. 2017. A never-ending story of per- and poly-fluoroalkyl substances (PFASs)? Env. Sci. & Tech., 51:2508-2518. Copyright 2017 American Chemical Society. 70

Structural Implications

▪ Diversity of PFAS structures has important implications for fate and transport processes

71

Polyfluorinated anion

Polyfluorinated zwitterion

Polyfluorinated cation

Images used with permission from Jennifer Field, Oregon State University

Properties of Anionic PFAAs

▪ Negatively-charged at all environmental and physiological pHs (4-10)

▪ Low vapor pressure and Henry’s Law (i.e. not volatile)◆ But can be present in airborne water droplets or sorbed to particulates

▪ Surfactants

▪ Water soluble

72

PFAA Sorption and Transport

Analyte # Carbons Koc1 Rf

PFBA 4 76 5

PFPeA 5 23 1.4

PFHxA 6 20 1.1

PFHpA 7 43 3

PFOA 8 78 5

PFNA 9 229 14

PFDA 10 912 57

PFUnA 11 3,600 225

PFBS 4 62 4

PFHxS 6 112 7

PFOS 8 631 39

▪ Sorption (Koc and Kd) (generally) increases with # of carbons

▪ Short-chain PFCAs have greater Koc

than expected

▪ GENERALLY:

◆ Solubility• PFCAs > PFSAs• Short chain > long chain

◆ Sorption• PFSAs > PFCAs• Long chain > short chain

◆ Relative partitioning• Soil, sediment, animals: PFSAs• Water, plants: PFCAs

1 Koc data from Guelfo, J.L., Higgins, C.P. Subsurface transport potential of perfluoroalkyl acids at aqueous film-forming foam (AFFF)-impacted sites. Environ. Sci. Technol. 2013. 47, 4164–4171.

73

Other factors impacting PFAA Transport

▪ Increased retardation (sorption)◆ Lower pH (more acidic)1,2

◆ Greater polyvalent cations1,2 (Ca2+, Fe3+, etc.)

◆ Presence of non-aqueous phase liquids3,4

▪ Retardation impacted by remedial approaches that change pH or introduces polyvalent cations (i.e., ISCO)2,4

1 Higgins and Luthy, 2006. ES&T; 2McKenzie et al., 2015 ES&T ; 3Guelfo and Higgins, 2013. ES&T; 4McKenzie et al., 2016. Water Research

Reprinted with permission from McKenzie et al. 2015. Effects of Chemical Oxidants on Perfluoroalkyl Acid Transport in One-Dimensional Porous Media Columns. Env. Sci. & Tech., 49:1681-1689. Copyright 2015 American Chemical Society.

74

Transport of polyfluorinated substances

▪ Transport related to charged state of PFAS ◆ Anions > zwitterions > cations

◆ Shorter chain lengths generally migrate faster

◆ pH impacts likely important

▪ Cationic and zwitterionic PFAS likely to sorb onto source-zone sediments due to cation exchange

▪ Biotic and abiotic transformation processes important◆ Source zone and near source polyfluorinated substances may act as

on-going sources for PFAAs

75

Biotransformation of PFAS1,2

1Weiner et al., 2013. Environ Chem; 2Harding-Marjanovic et al., 2015 ES&T; 3Backe et al., 2012. ES&T ; 4Rhoads et al.,

2008. ES&T ; 5Luo et al., 2015. ES&T Letters

6:2 FTSA

▪ Ansul transformation to FTSA (aerobic) explains high FTSA levels3 at AFFF sites

▪ Polyfluorinated ECF consumer product (primarily) PFAS biotransform to PFOS and other PFAS4

◆ No published studies on polyfluorinated ECF AFFF-derived PFAS

▪ PFAAs not expected to degrade

◆ Enzyme-based humification lab study5

suggests potential PFCA transformation

Reprinted with permission from Harding-Marjanovic, et al. 2015. Aerobic biotransformation

of fluorotelomer thioether amido sulfonate (lodyne) in AFFF-amended microcosms. Env.

Sci. & Tech., 49(13):7666-7674. Copyright 2015 American Chemical Society

76

Complexity Varies with Time, Space, and History

Old Distal Significant

RecentSourceZone None

Source: Adapted from figure by L. Trozzolo, TRC, used with permission 77

Complex

PFAS

Mixtures

Conceptual PFAS Fate and Transport at

AFFF Release Sites

78

Hydrocarbons biodegraded

PFAS plume expands

More aerobic

Precursors biotransformed to PFAAs

PFAS plume expands

Hydrocarbons degrades rapidly

Expansion of PFAS plume

Short chain PFAS migrate faster

Also look for surface

water features as

potential shortcuts to

transport PFAS into

GWGW Flow

ORP

+200 mV

-200 mV(Image from MS Office ClipArt)

Possible PFAS hot spot

from redox manipulations

via in-situ remediation

Possible PFAS

retardation (sorption)

due to high TOC

sediment

Transport in the Vadose Zone

79

▪ Chain-length dependent transport

▪ Sorption: Koc important, but not fully sufficient

▪ Low volatility

▪ Surfactant properties –PFAS likely adhere to air/water interfaces

Source: ITRC Environmental Fate and Transport fact sheet,


Vadose Zone Transport

▪ Many PFAS are air-water interface surfactants

▪ Retardation in the vadose zone due to the air-water interface expected to be significant

80

Breakthrough curves for PFOA transport in the 0.35 mm sand; C0 = 1

mg/L. Values in the legend refer to water saturation.

Source: Figure 2 - Ying et al. 2018

Reprinted with permission from Ying et al. 2018. Adsorption of PFOA at Air-Water Interface during Transport in Unsaturated Porous Media. Env. Sci. & Tech., 52:7745-7753. Copyright 2018 American Chemical Society.

PFAS-NAPL interactions are complexKNAPL values measured for dodecane (DD)

and trichlorethene (TCE) NAPLs

Analyte KDD (L/kg) ± KTCE (L/kg) ±

PFBA 0.23 0.24 0.86 0.60

PFPeA 0.50 0.34 1.72 0.72

PFHxA 2.20 0.60 1.85 0.37

PFHpA 1.32 0.35 1.50 0.59

PFOA 1.53 0.32 1.58 0.84

PFNA 2.66 0.81 1.98 1.73

PFDA 3.16 2.39 2.00 1.62

PFUnA 14.52 4.71 20.85 1.70

PFBS NM NM 0.19 0.17

PFHxS NM NM 0.22 0.22

PFOS 0.24 0.16 0.67 0.64

NM = no aqueous loss was measured.

81

-1

-0.5

0

0.5

1

1.5

-1 -0.5 0 0.5 1 1.5

LogK

dPredicted

LogKdMeasured

KddKtce1to12X

Measured sorption greater than

predicted assuming only

absorption into NAPL

Source: Guelfo and Higgins, 2013.

Reprinted with permission from Guelfo and Higgins 2013. Subsurface Transport Potential of Perfluoroalkyl Acids at Aqueous Film-Forming Foam (AFFF)-Impacted Sites. Env. Sci. & Tech., 47:4164-4171. Copyright 2013 American Chemical Society.

Atmospheric Transport▪ Particularly important for industrial sites with stack emissions

▪ Atmospheric deposition around industrial sites = large impacted areas



83

Example-

PFOA in GW

and Estimated

Air

Deposition

Images from Wood Environment & Infrastructure Solutions, Inc. – used with permission of client

Fate and Transport- Air

Transport in Groundwater

84

▪ Readily transported once in groundwater

▪ Composition may be impacted by remedial activities

▪ Be aware of groundwater-surface water interactions

Source: ITRC Environmental Fate and Transport fact sheet,


Minnesota Case Study: Groundwater-

Surface Water InteractionsGinny Yingling, MN Dept. of Health

PFAS in groundwater – Washington County, MN

▪ PFAAs highly soluble, mobile, persistent = very large plumes◆ Much larger than predicted by models

◆ Co-mingled plumes

▪ PFBA most widespread ◆ Extremely soluble and mobile = groundwater tracer

◆ Distal plume difficult to distinguish from “ambient” levels

▪ Distribution controlled by:◆ Groundwater divide (Mississippi R. and St. Croix R.)

◆ Bedrock features (buried valleys and faults)

◆ Groundwater - surface water interactions

◆ PFAS chemical properties (partitioning)

◆ Source area PFAS “signature”

◆ Groundwater pumping

Project 1007 – Stormwater Interconnect

l

Groundwater flow

Surface water

or

stormwater flow• Surface water transport

may move PFAS many miles away from source areas (See also: Awad et al., 2011 and Kwadijk et al., 2014).

• Infiltration along a surface water pathway may create discrete groundwater plumes isolated from the source.

• Groundwater discharge to surface water may contaminant water bodies distant from source areas.

Key Takeaways for Planning Site Investigations

▪ Perfluorinated PFAS:◆ Extremely stable◆ Mobility is chain-length dependent, affected by OC, pH, inorganic cations, etc.

▪ Non-polymeric polyfluorinated PFAS (precursors) are varying in their stability

◆ Much more variable in terms of transport

▪ Surfactant properties may lead to increased concentrations at air/water interface or at water/NAPL interface

▪ Source zones may be significant: long-term discharge potential◆ Exceptionally low criteria + high transport potential: investigation areas may be

larger than you’re used to◆ Oxidizing remedial techniques (ISCO, air sparge, aerobic bioremediation) can

transform precursors to persistent PFAAs

91

Everyone Stand Up

and Stretch!

PFAS Site CharacterizationShalene Thomas, Wood

Site Characterization▪ Phase I Site Investigation

◆ Conduct interview, document review and identify PFAS uses, applications and suspected source locations

◆ Install monitoring wells

◆ Monitor for presence and absence of regulated PFAS (may also include an evaluation of the other PFAS detected from analytical method and/or analysis of precursors for target compounds)

◆ Sampling

• Drinking water wells

• Groundwater from existing wells and source areas

◆ Identify primary migration pathways to sensitive receptors

94

3

2

1

Site Characterization

▪ Phase II Site Investigation

◆ Consider PFAS analytical list based on Phase I

information

◆ Expand investigation in the source area and along

property boundaries (e.g. more monitor well

installations)

◆ Include soil for source characterization

◆ Include outfall discharge, surface water and sediment

into site characterization

95

3

2

1


▪ Phase III Site Characterization

◆ Collect geochemical data, including anion and cation

concentrations and ion exchange capacity to understand

PFAS fate and transport

◆ Consider PFAA precursors

◆ Expand site investigation to confirm PFAS migration

pathways

◆ Collect samples from groundwater, soil, sediment and

surface water along PFAS migration pathways

◆ Consider off-site sampling

96

3

2

1

PFAS Sources

97


Industrial Sites

Landfills

WWTPs/Biosolids

PFAS Site Characterization

for


98

CSM for AFFF Application Sites



AFFF Source Identification

▪ Primary Sources◆ Fire fighting / crash sites

◆ Fire training areas

◆ Foam suppression systems

◆ Foam storage areas

◆ Fuel tank area with fire protection systems

▪ Secondary Sources◆ Untreated groundwater

◆ Wastewater

◆ Waste, discharges and disposals

100

Images from MS Office ClipArt

AFFF Contains a Highly Diverse Mixture of PFAS

Groundwater PFAS Concentration

Ranges at AFFF Sites

101

1

10

100

1,000

10,000

100,000

1,000,000

10,000,000

PFOS+PFOA PFOS PFOA PFHxS

Figure courtesy of AECOM

Max

Co

nc.

(n

g/L

)

Expect to find highPFAS concentrations

Conceptual PFAS Fate and Transport at

AFFF Release Sites

102

Hydrocarbons biodegraded

PFAS plume expands

More aerobic

Precursors biotransformed to PFAAs

PFAS plume expands

Hydrocarbons degrades rapidly

Expansion of PFAS plume

Short chain PFAS migrate faster

Also look for surface

water features as

potential shortcuts to

transport PFAS into

GWGW Flow

ORP

+200 mV

-200 mV(Image from MS Office ClipArt)

Possible PFAS hot spot

from redox manipulations

via in-situ remediation

Possible PFAS

retardation (sorption)

due to high TOC

sediment

Takeaway Messages on AFFF Release Sites

▪ Develop phased approach when characterizing PFAS

◆ Drinking water impact and source characterization are top priorities

to address

▪ PFOA and PFOS are not biodegradable and may be the terminal

products from PFAA precursors’ transformation.

▪ TOP assay can be used to estimate the presence of PFAA precursors

▪ Although PFAS partition, field data confirm they can still travel a

long way in groundwater

▪ AFFF Contains a Highly Diverse Mixture of PFAS

103


at

Industrial Facilities

104

CSM for Industrial Sites




▪ Important transport pathways:

◆ Air emission and deposition

◆ Water and process waste discharge w/o PFAS treatment

▪ Mixtures of target compounds may be site specific based on

manufacturing processes

▪ Other considerations:

◆ Off-site waste disposal areas?

◆ Secondary pathways (e.g., air deposition may result in contaminated

runoff)

106

Fluoropolymer Manufacturing Facility

Case Study

107

Figure courtesy of AECOM, used with permission of client


Case Study▪ PFOA used since the 1950s

▪ In 2000 PFOA found in a nearby PWS

▪ Investigation of the presence of PFOA in environmental media

▪ Site sources – air emissions, water discharges, on-site landfill

108Figure courtesy of AECOM, used with permission of client


Case Study

Investigation and Mitigation

▪ Sampling at public and private wells

▪ Concentrations decreased with increasing distance from the site

▪ PFOA in cistern samples

▪ Concentrations higher in primary wind flow direction

▪ Evolved regulatory climate leads to expanded investigation area

▪ GAC treatment systems installed for drinking water treatment at public water supplies and private wells since 2006

109

Facility

Figure courtesy of AECOM, used with permission of client

Site Characterization at

Landfills and Other Waste

Disposal Sites

110

(Image from MS Office ClipArt)

PFAS Transport from Landfills

▪ Unlined landfills have a higher potential of contributing

PFAS to groundwater

▪ PFAS will continue to release at slow but relatively steady

rates for decades

▪ With low infiltration rates, strong adsorption and low

solubility of the compounds, PFAS contained in waste may

take many years to reach the leachate

▪ PFAS in leachate and groundwater from landfills are

different than those at WWTPs and AFFF-contaminated

sites.

112

PFAS Compositions in Landfills

▪ Shorter-chain PFAS (three to six carbons) tend to

dominate

▪ 5:3 fluorotelomer carboxylic acid (FTCA) is a common

and often dominant constituent of PFAS found in landfills

◆ An indicator of PFAS in the environment originating

from landfills (Lang et al. 2017)

▪ PFAS may also be released to the air from landfills,

predominantly as fluorotelomer alcohols (FTOHs) and

perfluorobutanoate (PFBA) (Ahrens et al. 2011)

113

PFAS Concentrations in Landfills

▪ Depends on type of landfill, waste stream accepted, and local industries◆ Industrial waste and mixed municipal-industrial solid waste landfills

likely to have highest concentrations

◆ Municipal solid waste landfills have variable PFAS concentrations

◆ PFAS are detected in demolition debris landfills, but typically lower concentrations

▪ Highest concentrations typically in leachate (µg/L to mg/L)

▪ Groundwater concentrations typically are lower (ng/L to µg/L)

114

Wastewater Treatment and

Biosolid Application Sites

115

This Photo by City of Geneva from flickr is licensed under CC BY-NC

http://www.flickr.com/photos/cityofgeneva/4110495585/

https://creativecommons.org/licenses/by-nc/2.0/

WWTP and Biosolids

▪ Effluent and application provide a pathway for PFAS to enter the

environment

▪ There is a need to investigate PFAS compositions

◆ Types and concentrations of PFAS received by the WWTP

◆ When WWTP involves biological and chemical processes, PFAA

precursors can be transformed to intermediate and terminal

degradation products, including PFAAs

• Investigate influent and effluent of each treatment process

▪ There is a need to investigate pathways for PFAS releases into

environment

◆ Point discharges

◆ Land applications of biosolids

◆ Surface runoff and infiltration into groundwater

117

Monitoring for PFAS at WWTP

▪ Influent, intermediate and effluent of each WWTP treatment

flow process

▪ Collect, monitor and manage waste streams generated from

treatment processes that can concentrate PFAS, for instance:

◆ Off-gas and off-gas treatment system

◆ Sludge and biosolids

◆ Spent media

◆ Liquid wastes

▪ Outfall discharge points

▪ Surface runoff and drainage channels for surface water,

sediment, and groundwater

▪ Retention basins

118

Image from MS Office ClipArt

Takeaway Messages –

Landfill and WWTP

▪ Landfill and WWTP sources have been less investigated

and just recently received attention

▪ Landfill compositions are different from PFAS releases

associated with AFFF and manufacturing processes

▪ The landfill leachate compositions verify the concerns of

ubiquitous nature of PFAS

▪ More, newer PFAS compounds may be identified due to

the use of new PFAS compounds for manufacturing

119

PFAS Sampling & AnalysisShalene Thomas, Wood

Why do we need to be concerned

about cross-contamination?

▪ PFAS are ubiquitous and have been used to

manufacture items for personal uses and environmental

site investigations

▪ Much of our typical sampling equipment and items in the

sampling environment contain or may contain PFAS

▪ Lowering of screening criteria and detection limits in labs

121

Images from MS Office ClipArt

Personal Protection ProductsThere is little published research on how certain materials may affect sample results. Therefore, a conservative approach is recommended during execution of the sampling plan

These materials are not of concern so long as they do not come into contact with the sample or sample container

122

Safe to use

•Synthetic or natural fibers, well laundered, cotton coveralls,

PVC

Try to avoid

•Water-repellent textiles, insect repellent and sun screen

Need verification

•Non-brand name, water-resistant, waterproof, or stain-

treated clothing

•Tyvek suits and clothing that contains “Tyvek”

General Practice

123

Good practice

▪Wash hands, wear powderless nitrile gloves and change them before

every sample is collected

▪Only open sample container during sample collection and never set the

sample container lid down

Try to avoid

▪Any materials/supplies that will come into contact with the sample that

are known to contain or are suspected to contain PFAS

▪Addition of sample processing steps (e.g., filtration) in the field that

could be performed under the more controlled conditions of the

laboratory

Need verification

•Use of markers, which ones are acceptable and where ok to use

Sampling Equipment

124

Do Not Use Acceptable Alternatives

Fluoropolymer bailers or

pump bladders

Disposable Equipment

Dedicated Equipment (no polytetrafluoroethylene

(PTFE) parts)

Fluoropolymer tubing,

valves and other parts in

pumps

High-density polypropylene, high-density

polyethylene (HDPE) and silicon materials (i.e.

tubing)

LDPE HydraSleeves™ HDPE HydraSleeves™

Freezer packs or “blue” ice

packs

“Wet” ice in double-sealed zipper bags or dry ice

Sample Containers and Blank

Water Source

▪ Sample containers (polypropylene or HDPE) and water

used for blanks in the field and for final rinse of equipment

should:

◆ be supplied by the lab performing the analysis, and

◆ be verified as being PFAS-free (as defined by the project) prior to

use.

▪ If source water is used in the field for any blanks or final

rinse, a sample of this water should be sent to the

laboratory for analysis.

125

What To Do If You Are Unsure

If Item Contains PFAS Or Not?

▪ Review the Safety Data Sheets and consult with the

manufacturer of the item

▪ Consult:

◆ PFAS sampling guidance documents

◆ PFAS resources within your organization

◆ An analytical chemist with PFAS experience

▪ Collect equipment blank(s) from a specific item in question or

send a section or piece of the equipment (if practical) to the

laboratory for a more vigorous leachate analysis

126

?

ERR ON THE SIDE OF BEING CAUTIOUS

RATHER THAN BEING UNSURE AND RISK CROSS-CONTAMINATION

Planning for Laboratory Analysis

▪ Laboratory must provide all containers, PFAS-free water for

sampling and methanol, in some cases, for equipment

rinsing

▪ All materials from laboratory to the samplers should be pre-

tested for PFAS-free

▪ Project team must discuss with the laboratory:

◆ the PFAS to be analyzed and project reporting levels,

◆ the volume of sample required to achieve the lab

reporting levels,

◆ project sample preparation requirements, and

◆ the number of bottles needed, including QC samples.

127

Planning for Laboratory Analysis

▪ Provide laboratory information on high concentration

samples

▪ Request laboratory screen all samples prior to sample

preparation (additional containers will be needed for this)

128

Filtering of Water Samples

▪ Evidence that PFOS may sorb onto various filters (e.g.,

glass fiber filters)

▪ Filtered/unfiltered data may be misinterpreted as PFOS

sorbed to soil or sediment in the water sample when the

reduction may actually reflect PFOS sorbed onto the glass

fiber filter

▪ Consider use of low flow sampling or use of a centrifuge in

the lab

129

Other PFAS Sampling Precautions

▪ Many PFAS sampling concerns are precautionary and have

no scientific data to prove

▪ HDPE can sorb PFAS as well (evidence of strong 6:2 FtS

sorption)

▪ Laboratory should empty the entire sample bottle for

extraction, sub-sampling from the sample bottle must be

avoided

◆ The empty bottle should be rinsed with methanol to desorb any

PFAS on the sample bottle regardless bottle materials

◆ The rinsate should be combined with the sample materials for

analysis

130

QA/QC Sample Collection

Using blanks to evaluate composition or suitable nature of

equipment/supplies for sampling, and to assess possibility of

cross-contamination during sampling/transport/storage

◆Pre-investigation equipment blanks

◆Equipment blanks

◆Field reagent blanks

◆Trip blank

131

Compound-Specific Analysis of PFAS

▪ All utilize liquid chromatography tandem mass spectrometry

(LC-MS/MS)

▪ Some of the same equipment and supply concerns

associated with field sampling apply to sample analysis

▪ Various quantitation “schemes”

◆ External standard

◆ Internal standard

◆ Isotope dilution

97

Published PFAS Analytical Methods

▪ USEPA 537.1

◆ Compound-Specific Analyses (18 PFAS)

◆ Drinking Water

◆ Laboratories allowed some modifications, but not:

▪ Sample collection/preservation

▪ Extraction

▪ Quality control

◆ Multi-laboratory validated method

Shoemaker, Tettenhorst 2018

133

EPA Method 537.1 November 2018

134

Analytes Analyte Name Analytes Analyte Name

HFPO-DA Hexafluoropropylene oxide dimer acid PFNA Perfluorononanoic acid

NEtFOSAAN-ethyl

perfluorooctanesulfonamidoacetic acidPFOS Perfluorooctane sulfonic acid

NMeFOSAAN-methyl

perfluorooctanesulfonamidoacetic acidPFOA Perfluorooctanoic acid

PFBS Perfluorobutane sulfonic acid PFTA Perfluorotetradecanoic acid

PFDA Perfluorodecanoic acid PFTrDA Perfluorotridecanoic acid

PFDoA Perfluorododecanoic acid PFUnA Perfluoroundecanoic acid

PFHpA Perfluoroheptanoic acid 11Cl-PF3OUdS11-chloroeicosafluoro-3-oxaundecane-1-

sulfonic acid

PFHxS Perfluorohexane sulfonic acid 9Cl-PF3ONS9-chlorohexadecafluoro-3-oxanone-1-

sulfonic acid

PFHxAPerfluorohexanoic acid ADONA 4,8-dioxa-3H-perfluorononanoic acid

Source: Shoemaker and Tettenhorst 2018

Other Published PFAS Analytical Methods

▪ ISO Method 25101 (ISO 2009)


▪ PFOA

▪ PFOS

◆ Unfiltered Drinking Water, Ground Water, and Surface

Water


135

Other Published PFAS Analytical Methods

▪ ASTM D7979-17 (ASTM 2017)


◆ Water, Sludge, Influent, Effluent, and Wastewater

◆ Single laboratory validated method

▪ ASTM D7968-17a (ASTM 2017)


◆ Soil

◆ Single laboratory validated method

136

ASTM D7979-17 & ASTM D7968-17a

137

Analytes Analyte Name Analytes Analyte Name

PFTreA Perfluorotetradecanoic acid PFHpA Perfluoroheptanoic acid

PFTriA Perfluorotridecanoic acid PFHxA Perfluorohexanoic acid

PFDoA Perfluorododecanoic acid PFBS Perfluorobutane sulfonic acid

PFUnA Perfluoroundecanoic acid PFPeA Perfluoropentanoic acid

PFDA Perfluorodecanoic acid PFBA Perfluorobutanoic acid

PFOS Perfluorooctane sulfonic acid FHEA 2-perfluorohexyl ethanoic acid

PFNA Perfluorononanoic acid FOEA 2-perfluorooctyl ethanoic acid

PFecHSDecafluoro-4-(pentafluoroethyl)

cyclohexanesulfonic acid

FDEA 2-perfluorodeptyl ethanoic acid

FOUEA 2H-perfluoro-2-decenoic acid

PFOA Perfluorooctanoic acid FHpPA 3-perfluoroheptyl propanoic acid

PFHxS Perfluorohexane sulfonic acid FHUEA 2H-perfluoro-2-octenoic acid

www.astm.org

PFAS Methods In Development

▪ USEPA new drinking water method currently in development:

◆ Compound-Specific Analyses (targeting 25 PFAS)

◆ Addresses poor performance of Method 537.1


◆ Publish method in 2019

138Source: USEPA PFAS Research Webinar - Methods and Guidance for Sampling and Analyzing Environmental Media, November 28, 2018

▪ USEPA SW-846 draft methods 8327 and 8328

◆ 8327 - Non-potable aqueous samples, targeting 24 PFAS

◆ 8328 - Non-potable aqueous and solid samples, targeting 25 PFAS

(including GenX process compounds)


◆ Publish draft method in 2019 for public comment

Proposed Analyte Lists for USEPA SW-846

Methods 8327 and 8328

139

Analytes Analyte Name Analytes Analyte NamePFTreA Perfluorotetradecanoic acid PFHpA Perfluoroheptanoic acidPFTriA Perfluorotridecanoic acid PFHxA Perfluorohexanoic acidPFDoA Perfluorododecanoic acid PFBS Perfluorobutane sulfonic acidPFUnA Perfluoroundecanoic acid PFPeS Perfluoropentane sulfonic acidPFDA Perfluorodecanoic acid PFPeA Perfluoropentanoic acidPFDS Perfluorodecane sulfonic acid PFBA Perfluorobutanoic acidPFOS Perfluorooctane sulfonic acid FOSA Perfluorooctane sulfonamide PFNA Perfluorononanoic acid 4:2 FTS 4:2 Perfluorohexane sulfonic acidPFNS Perfluorononane sulfonic acid 6:2 FTS 6:2 Perfluorooctane sulfonic acid PFOA Perfluorooctanoic acid 8:2 FTS 8:2 Perfluorodexane sulfonic acid

PFHpS Perfluoroheptane sulfonic acid NEtFOSAAN-ethylperfluorooctanesulfonamidoacetic acid

PFHxS Perfluorohexane sulfonic acid NMeFOSAAN-methylperfluorooctane

sulfonamidoacetic acidPFHpA Perfluoroheptanoic acid

HFPO-DA*Hexafluoropropylene oxide

dimer acidPFOS Perfluorooctane sulfonic acid

* Only applicable to USEPA SW-846 Method 8328

Branched & Linear PFAS

▪ PFAS from ECF chemistry: ~22 ± 1.2% branched and 78 ± 1.2% linear

isomer1

▪ Branched and linear isomers of PFAS (including PFCAs) produced by

ECF seen in consumer products, groundwater, sediment, soil,

wastewater, landfills

▪ Observing branched isomers depends on chromatography

▪ Linear isomers have greater retention on C18 analytical columns -

branched isomers are more compact (elute earlier)

▪ If ignoring the branched peak, concentrations will be low by ~ 25%

▪ Telomer chemistry theoretically produces predominantly linear PFAS,

however, final product may contain branched isomers.

linear isomerbranched isomers-

10 co-eluting in

single peak

1 Giesy and Kannan, 2002; Schultz et al., 2003;

Benskin et al. 2010; Riddell et al. 2009103

Figure courtesy C. Higgins

Less-Standardized Analyses

▪ Particle-Induced Gamma Emission (PIGE) spectroscopy

measures elemental fluorine from a sample isolated on a thin

surface

▪ Precursor Analysis by Total Oxidizable Precursor (TOP) Assay

measures PFAA precursors or polyfluorinated compounds that can

be converted to PFAAs

▪ LC quadrupole time-of-flight mass spectrometry (LC-QToF-MS)

tentatively identifies PFAS structures through library matches

▪ Extractable/Absorbable Organic Fluorine (EOF/AOF) measures

fluorine in a sample as fluoride

141

TOP Assay: Screening for Total PFAS

▪ Limited PFAA precursors can be characterized using USEPA 537 or

USEPA 537 Mod methods

▪ TOP (Total Oxidizable Precursors) Assay is not an USEPA method but

is commercially available

➢ The method oxidizes PFAA precursors abiotically to PFCAs only

➢ TOP does not close PFAS mass balance

➢ TOP data do not identify the origins of precursors

➢ TOP data do not represent biotransformation under natural

conditions

➢ But… it is the only commercialized screening tool to check on the

presence of PFAA precursors

142

Treatment TechnologiesShalene Thomas

Wood Plc

PFAS Treatment Technologies

ITRC Defined Three Categories:

▪ Field Implemented Technologies – Technologies that have been demonstrated under full-scale conditions at multiple sites, by multiple practitioners and multiple applications are well documented in peer-reviewed literature

▪ Limited Application Technologies – Technologies that have been implemented on a limited number of sites, by a limited number of practitioners, and may not have been documented in peer-reviewed literature.

▪ Developing Technologies – Technologies that have been researched at the laboratory or bench scale, but these technologies have not been field demonstrated.

144

Water Treatment▪ Effective conventional approaches, with limitations:

◆ Carbon adsorption

◆ Resin adsorption

◆ Reverse osmosis

▪ Typically ineffective conventional technologies:◆ Air stripping, air sparging

▪ Technologies in development:◆ Examples include - bioremediation, chemical oxidation, chemical

reduction, thermal desorption, electrochemical, others

▪ Be aware of precursor transformations via treatment

processes, particularly with oxidation and biodegradation

▪ Treatment objectives can drive the decision making

145

Activated Carbon▪ Granular Activated Carbon (GAC)

most widely used technology.

▪ GAC performance varies based on site-specific conditions, carbon source types and manufacturing methods.

▪ Shorter-chain PFAS break through faster than longer chain, but generally still within the range considered feasible.

▪ GAC less effective for PFCAs than PFSAs of same C-F chain length.

146

Photo used with permission: Calgon Carbon Corporation, 2018

Typical GAC Process Diagram

▪ Influent GAC vessel◆ “Lead”

▪ Second GAC vessel◆ “Lag”

▪ Monitoring◆ Influent

◆ Mid-point

◆ Effluent

▪ Carbon Change Out◆ Lead to reactivation

◆ Lag to lead

◆ New to lag

147

EBCT – Empty bed contact time

Diagram used with permission: Calgon Carbon Corporation, 2018

Reactivated Carbon

▪ GAC can be “reactivated” under high temperature and reused.

▪ Less aggressive “regeneration” methods are not appropriate for PFAS.

▪ Contract reactivation services provided by most GAC suppliers (e.g., round trip service).

▪ Reactivated carbon typically used in wastewater and groundwater remediation applications.

▪ For drinking water applications, reactivated carbon should be used with caution to avoid commingling with carbon from other sources. Must comply with AWWA B605-13 Reactivation of Granular Activated Carbon standard.

148

Column Testing Example

▪ Less effective for shorter chain carbon compounds (PFBS and PFHxA).

▪ Differences between sulfonates and carboxylates.

▪ Initial breakthrough above detection: ◆ PFBS at 256 days.

◆ PFHxA at 311 days.

◆ PFHpA at 367 days.

0

2

4

6

8

10

12

14

16

18

20

0 200 400 600 800 1,000 1,200P

FA

S C

on

cen

trati

on

, n

g/L

Simulated Days of Operation

PFBSPFBS Average InfluentPFHpAPFHpA Average Influent

149

Graph courtesy of Langan, with permission of client.

In Situ Sorption▪ Colloidal activated carbon with a biopolymer

▪ Technology widely demonstrated for VOCs

▪ Can be installed as a treatment barrier

150

Before Treatment

Treatment zone with 20 inj points

30 Months After Injection

Graphics used with permission of Regenesis, Inc., after: Rick McGregor, Remediation, 2018; 28:33-41

▪ Full-scale demonstrations at several sites

▪ Unknown longevity, but modeling predicts >100 years

Ion Exchange (IX) Resin vs. GAC

GAC removes by adsorption

using hydrophobic “Tail”

PFOS – Perfluorooctane Sulfonate

Selective IX Resins removes by both ion exchange

and adsorption using both “Head” & “Tail”

151

Figure Courtesy of Langan/Adapted from Purolite

Sulfonate group

Hydrophobic “Tail” Ionized “Head”

-

Single-Use Selective Resin + Incineration

Short Contact Time ~3 minsSimple & Effective - Operator Preferred

Incineration or other disposal alternative

Treated waterPFAS in water

Illustrations courtesy of Purolite, Inc.

152

Single-Use Selective Resin ▪ Simple, field-demonstrated

▪ High removal effectiveness

▪ Small footprint/headspace

▪ High operating capacity ◆ 100,000 to 350,000 BV

▪ Operation costs ◆ Need to be based upon site-

specific resin usage rates and disposal costs

153

Example Ion Exchange Removal Curves at Specific Influent Concentrations

Data courtesy of Purolite, Inc.

Regenerable Resin Process

154

PFAS

Image provided courtesy of ECT and Wood

Reverse Osmosis▪ Membrane Processes

▪ Effective for PFAS◆ High pressure membrane◆ High energy usage◆ Reject water disposal◆ Typically used on lower flow rates◆ Questions about sustainability

▪ Removes a wide range of constituents:◆ Including hardness, dissolved solids, as well as VOCs and PFAS

155

Flocculation/Coagulation

▪ Pre-treatment technology ▪ Many products have been tested:

◆ Alum, ferrate, ferric sulfate, Polydiallyldimethylammonium chloride (polyDADMAC)

▪ Multiple flocculants can be used to address varied chain lengths

▪ Pilot-scale systems in Europe▪ Sludge disposal is needed▪ Carbon or Resin Polishing

◆ Results in less disposal quantities than GAC directly

◆ Non-detect concentrations with adsorbent polishing

Photos courtesy of Bill DiGuiseppi, Jacobs

156

Developing Separation Technologies▪ Zeolites

◆ Microporous aluminosilicate minerals

◆ Limited testing beyond PFOS/PFOA

◆ Less sorptive than GAC

◆ Requires disposal/destruction of media

▪ Foam Fractionation◆ Air microbubbles separate PFAS

◆ Demonstrated in Australia

▪ Biochar◆ Pyrolyzed biomass to create

charcoal

◆ Demonstrated on wide variety of PFAS

◆ Limited effectiveness on short-chain PFAS

◆ Competitive sorption an issue

◆ Requires disposal/destruction of media

157

PAC+Additives* Ex-Situ Adsorption

▪ Evaluated in Australia, U.S. and Germany

▪ Passed PFAS contaminated water (1.8 mg/L) through two different columns, up to 100 pore volumes◆ One column with activated carbon

◆ One column with powder activated carbon and additives

▪ Evaluated short- and long-chain PFAS

▪ Removed shorter chain PFAS more effectively than activated carbon alone

* Rembind™. Data courtesy of Ziltek Pty Ltd.158

181

Electrochemical Coagulation▪ Electrical charges generate metal hydroxide floc

▪ Floc is polar and sorbs to PFAS

▪ Optimal energy, plate material, and pH control kinetics

▪ Zinc anode shown to be best

▪ Waste sludge disposal is needed

159

Zn2+

Al3+

PFOA

ZnO/Zn0.70Al0.30(OH)2(CO3)0.15•xH2O

Figure courtesy of Bill DiGuiseppi, Jacobs

▪ Use of direct current (DC) to degrade PFAS◆ Electrode material (Boron-doped diamond, MMO, lead-dioxide etc.)

◆ Major byproducts: Fluoride ions, shorter-chain PFAS, perchlorate

◆ Limitations

Electrochemical Oxidation

160Reprinted with permission from Schaefer, et al., 2015. Electrochemical treatment of perfluorooctanoic

acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in groundwater impacted by aqueous film forming

foams (AFFFs). Jour. Haz. Materials., 295:170-175. Copyright 2015 Elsevier.

Source: Schaefer et al. 2015

Oxidation/Reduction Approaches▪ Activated Persulfate

◆ High-temperature activation found to oxidize PFCAs, but not PFSA. Subject of current SERDP research.

▪ Photolysis◆ Typically in presence of catalyst

◆ Geochemistry has profound effect

▪ E-Beam◆ Established, but not common, destructive technology for other

recalcitrant chemicals

◆ Tested for PFAS in academic lab

◆ Oxidizing/reducing chemical reactions

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Chemical Reduction

▪ Zero Valent Metals◆ Combination of sorption onto iron as well as

reduction via dehydrohalogenation

▪ Ultraviolet light + sulfite◆ Creates hydrated electrons, strong reducing

agents that react with carboxylates and sulfonates

◆ Could be used for concentrate destruction

▪ Vitamin B12 with titanium citrate◆ Limited bench tests◆ Primarily attacks branched vs linear PFOS◆ Required high heat and pH in some cases

162

Images courtesy of Timm Strathmann, Colorado School of Mines

HPLC Ret Time (min)

Before Treatment

HPLC Ret Time (min)

After 2nd Sulfite Add

Sonolysis (Ultrasound)▪ Sound waves >19 kHz create

cavities in liquids

▪ Cavities collapse at maximum radius creating extreme localized conditions ◆ High heat (50000K)

◆ High pressure (1000 bar)

▪ PFAS sorb to the cavity interface

▪ Cavity collapses◆ Cleaves bond between hydrophobic

and hydrophilic portions of molecules

163Figures courtesy of Michelle Crimi, Clarkson

Plasma Treatment

▪ Uses electricity to convert water into mixture of highly reactive species◆ OH•, O, H•, HO2

•, O2•‒, H2, O2, H2O2 and

aqueous electrons (e‒aq)

▪ Plasma formed by means of electrical discharge between one high voltage and one groundwater within or contacting the water

▪ Argon gas pumped through diffuser◆ Produces bubble layer on surface that

concentrates PFAS

164

Photos courtesy of Selma Mededovic, Clarkson

Stratton, G.R., et al. (2015). Chemical Engineering

Journal, 273: 543-550.

Stratton, G. R., et al., (2017). Environmental Science &

Technology 2017, 51(3):1643-1648.

Combined Remedy: Separate and Destroy

▪ In situ precursor transformation with oxidation

▪ Ex situ IX: regenerable resin

▪ Plasma destruction of concentrated PFAS in liquid

165SERDP ER18-1306; ESTCP ER-5015

Figure courtesy of Michelle Crimi, Clarkson

Soil Remediation Technologies

▪ Conventional◆ Excavation and landfill

◆ Excavation and offsite incineration

◆ Stabilization

▪ Developing/Limited demonstrations◆ Soil Washing

◆ Thermal

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Excavation

▪ Excavation with offsite disposal in a permitted landfill, where allowed. ◆ Out of abundance of caution, some

landfills no longer will accept PFAS soils. Do not assume this is straightforward.

▪ Excavation with offsite incineration◆ Must be >1,100oC for PFAS

◆ Destruction assumed but not well documented

167

Photo courtesy of CH2M/Jacobs

Stabilization / Immobilization▪ Stabilization/Immobilization

via sorption▪ Combination of powder-

based reagents with high surface area and various binding methods:◆ Powdered activated carbon,

aluminum hydroxide, kaolin clay◆ Added from 1-5% by weight to soil◆ Fully commercial & demonstrated

in Australia◆ Extensive testing, research and

demonstration in Europe

Images courtesy of Ziltek™ and AquaBlok Ltd.

168

168

Treatability Study: PFOS/PFOA in Soil ▪ Two commercial airport sites in Australia

▪ Site soils mixed with proprietary combination of GAC and additives at various addition rates

▪ Soil leachates prepared using the Toxicity Characteristic Leaching Procedure (TCLP)

Data courtesy of Ziltek Pty Ltd.

169

169

Soil Stabilization Example

Photos and information courtesy of Ziltek Pty Ltd.Cell design graphic courtesy of Langan

▪ 1,100 tons PFAS impacted soils stabilized on-site at two airports during upgrade activities.

▪ Transport and disposal in a purpose-built burial cell located at a municipal waste landfill site.

▪ Cell lined and covered with stabilization agent.

▪ EPA Test Method 1311 and 1320 (TCLP and MEP) to verify performance.

Soil Burial Cell Design

170

Soil Separation/Washing

▪ A handful of bench and pilot scale tests◆ Torneman, 2017 – Two sites in Sweden

◆ Ventia, 2018 – One site in Australia

▪ Minimally documented, but available results are positive

▪ Lower throughput for clay-rich soils

▪ Treatment of multiple waste streams (water, sludge) required

▪ Dry sieving may concentrate PFAS in limited volume fraction (i.e., clays and organic fines)

171

Thermal Desorption for PFAS in Soil

172

▪ Bench scale information

▪ Targeted for unsaturated zone AFFF source areas

▪ Would require wet scrubber and scrubber water treatment (GAC)

▪ Air discharge control would be needed

Initial Total

PFAS Conc.

(µg/kg)

% Decrease

in Total PFAS

Exposure

Temperature/

Time

Number of

PFAS

Analyzed

200 26 250°C 8 days 29

15140

99.4

300°C 4 days

350°C 2 days29

290

89.3-99.8

97.3->99.9*

99.8->99.9*

400°C 60 mins

550°C 50 mins

700°C 80 mins

29

* >99.9% decreases are based on the limited analytical suite performed and based on decreases below the Limits of Detection

Data courtesy of William DiGuiseppi, Jacobs

PFAS Remediation Technologies: Takeaways

▪ There are a lot of technologies with promise to treat PFAS

▪ There are only a few that are considered field implemented◆ Excavation and incineration or sorption/stabilization for soil

◆ Pump and treat with GAC, membrane filtration, or ion exchange for water

▪ Limited application approaches◆ Thermal desorption or soil washing for soil

◆ Injectable sorbents, coagulants for water

▪ Developing technologies◆ Destructive chemical treatment

▪ Treatment trains (combinations of unit processes) should be considered

▪ Treatability and pilot studies are the norm

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Questions?

Speakers

▪ Shalene Thomas, Wood Environment & Infrastructure Solutions

◆ +1 612-490-7606

◆ [email protected]

▪ Ginny Yingling, Minnesota Dept. of Health

◆ +1 651-201-4930

◆ [email protected]

175

mailto:[email protected]

mailto:[email protected]

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