passive sampling for measuring freely dissolved ......passive sampler (c sampler) •units –ng/g...

24th Annual NARPM Training Program

Passive

Sampling

for Measuring Freely

Dissolved Contaminants

in Sediments: Basics, Principles &

Applications

Robert M Burgess

U.S. EPA ORD NHEERL

Atlantic Ecology Division

Narragansett, RI, USA

25th

24th Annual NARPM Training Program 1

OUTLINE

Why use passive sampling methods (PSM) and what they tell us

Why do we care about the freely dissolved concentration (Cfree)

Types of PSM and how they work

Preparing, deploying, recovering, and storing PSM

Analyzing PSM data

Evaluating PSM applications

Summary

Focus on nonionic organic contaminants (no metals)

PCBs DDTs

Dioxins

PAHs Furans

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(1) Freely dissolved concentrations (Cfree) of contaminants of concern (COC) in water around passive sampler • Surrogate for bioavailable concentrations of COC

• Media

– Porewater (Interstitial Water)

– Water column

• Compare to Water Quality Criteria (WQC), other water quality standards, sediment guidelines or water-only toxicity data

(2) Concentration of COCs in passive sampler

• Evidence of correlation with bioaccumulation by aquatic organisms

• Serve as surrogates for biomonitoring organisms

– Benthic and water column organisms

– Especially in situations where mussels or fish cannot be used (e.g., low dissolved oxygen, toxicity, low/high temperature constraints (ice))

√

√

WHY USE PASSIVE SAMPLING METHODS

(PSM) AND WHAT THEY TELL US

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WHY DO WE CARE ABOUT THE FREELY

DISSOLVED CONCENTRATION (CFREE)?

For benthic organisms: What media is an effective surrogate for

exposure to bioavailable chemicals?

Sediment?

Food?

Water column?

Pore Water = Freely dissolved?

Adams et al. (1985) addressed this question

Two Kepone-amended sediments (same levels)

• 1.5% and 12.3% Sediment organic carbon

Freshwater midge (Chironomus tentans)

Flow-through and static 14 day exposures

Acute and chronic (growth) endpoints

Exposure-response relationships

• Survival and growth versus exposure

Chironomus tentans

=

Kepone

√

√

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Sediment Concentration

(mg Kepone/Kg sediment (dry))

Mid

ge S

urv

ival (%

)

1.5% Organic

carbon/Kg

sediment (dry)

12.3 % Organic

carbon/Kg

sediment (dry)

25

75

Water Column

Food

What media is an effective

surrogate for exposure to

bioavailable chemicals?

Sediment

50

0

100

20 40 80 60

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Freely Dissolved Concentration (Cfree)

(µg Kepone/L Pore water)

Mid

ge S

urv

ival (%

)

1.5% Organic

carbon/Kg

sediment (dry)

12.3 % Organic

carbon/Kg

sediment (dry)

50

0

100

12.5 25 50 37.5

25

75

Water Column

Food

What media is an effective

surrogate for exposure

to bioavailable chemicals?

Sediment

Pore Water √

Pore Water Concentration

(µg Kepone/L Pore water)

Freely Dissolved

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Is there another sampling method for measuring the freely dissolved concentrations (Cfree) of

contaminants?

Measuring freely dissolved concentrations (Cfree) in the pore waters and water column Why not continue to use conventional sampling methods? Some problems:

Pore Water

• Centrifugation or squeezing pore water results in limited volumes

• Several artifacts including losses to filters and surfaces and contamination by colloids and small particles reduce accuracy of analysis

• Collecting large volumes of pore waters is logistically challenging, scientifically dodgy and generally expensive

Water Column

• Logistically and technically difficult to collect and extract large volumes of surface water

• Same artifacts as pore water collection

• Analytical detection limits are often not sufficiently low

√

√

WHY USE PASSIVE SAMPLING METHODS

(PSM) AND WHAT THEY TELL US

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Atmosphere

Water

Contaminated Sediments


Diffusion/Advection


WHY USE PSM AND WHAT THEY TELL US

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Diffusion with replacement to maintain equilibrium Bioaccumulation with replacement to maintain equilibrium Passive sampling with replacement to maintain equilibrium

In equilibrium systems… there is equilibrium partitioning

and there are partition coefficients

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Time (days)

Fre

ely

Dis

solv

ed

Pore

wate

r C

oncentr

ation (

Cfr

ee)

(ng/L

)

0 30

Resuspension Event (water column intrusion)

Actual

Cfree

“Time-averaged” or

“time-integrated”

measurement


Passive sampler-based

Cfree

For your average contaminated sediment –

How does pore water Cfree behave?

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Atmosphere

Water



Atmosphere

Water


TYPES OF PSM AND HOW THEY WORK

(Cfree)

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Polyethylene (PE) Polyoxymethylene (POM)

PE 25 - 50 µm thick

POM

75 µm thick


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0.2

5 m

2.5 cm

SPME

fiber-optic cable

2.5 cm

50 - 95 um thick polyethylene shell

containing synthetic lipid triolien

cross-section SPMD

triolien layer

Solid Phase

Microextraction (SPME) Semi-Permeable

Membrane Device (SPMD)


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HI

CI

H

HI

CI

H

HI

CI

H

HI

CI

H

HI

CI

H

HI

CI

H

(a)

(c)

(b)

H

I

H - C - HI

SiI

H - C - H

I

H

O

H

I

H - C - HI

SiI

H - C - H

I

H

O

H

I

H - C - HI

SiI

H - C - H

I

H

O

H

I

H - C - HI

SiI

H - C - H

I

H

HI

CI

H

HI

CI

H

HI

CI

H

HI

CI

H OO O

Polyethylene

Polydimethylsiloxane

Polyoxymethylene

Atom Key:

White = Hydrogen

Black = Carbon

Red = Oxygen

Grey = Silicon

Green = Chlorine


“Like Dissolves Like”

(i.e., contaminants

dissolve into the polymers)

PCB molecule

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Pore water

Passive Sampler

(e.g., PE, POM, SPME) Initial concentration of PCBs in

passive sampler = 0 ng/g

PCB molecule (Cfree form)


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Deployment Time (days)

Concentr

ation

(ng/g

Passiv

e S

am

ple

r)

Equilibrium Sampling


0 30

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Concentr

ation

(ng/g

Passiv

e S

am

ple

r) = Equilibrium *

√

√

√

Equilibrium Sampling


Cfree is the freely dissolved concentration

of a contaminant (ng/mL),

CSampler is the passive sampler

concentration (ng/g),

KSampler-free is the passive sampler-

dissolved partition coefficient (mL/g)

Freely Dissolved

Concentration (Cfree)

freeSampler

Sampler

free K

CC

0 30

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Number of peer-reviewed publications by PSM

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0

5

10

15

20

25

Nu

mb

er

of P

ub

lica

tio

ns

Year


Polyoxymethylene

Polyethylene

0

5

10

15

20

25

Nu

mb

er

of P

ub

lica

tio

ns

Year

DGT


Polyoxymethylene

Polyethylene


Superfund sites where PSMs have been used (Updated 2 November 2017):

Allegany Ballistics Laboratory (Region 3)

Aniston PCB (Region 4)

Berry’s Creek (Region 2)

Brodhead Creek (Region 3)

Columbia Slough (Region 10)

Dover Gas Light (Region 3)

Diamond Alkali (Region 2)

Grand Calumet (GLNPO-Region 5)

Grasse River (Region 2)

Lake Hartwell (Region 4)

Lower Duwamish Waterway (Region 10)

Manistique River (Region 5)

McCormick and Baxter (Region 10)


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Metal Bank (Region 3)

MW Manufacturing (Region 3)

Naval Station Newport (Region 1)

New Bedford Harbor (Region 1)

Ordot Landfill (Region 9)

Pacific Sound Resources (Region 10)

Palos Verdes Shelf (Region 9)

Portland Harbor (Region 10)

San Jacinto Waste Pits (Region 6)

Tennessee Products (Region 4)

United Heckathorn (Region 9)

Whitmoyer Laboratories (Region 3)

Wyckoff (Region 10)


Passive

Sampler

(PE or POM)

(1) Solvent Cleaning

(~24 hours)

(2) Deployment and

Recovery (~ 30 days)

(4) Solvent Extraction (48 hours) (6) GC/MS Analysis and

Data Interpretation (5) Volume reduction (~ 1 hour)

(3) Storage

(-4 ˚C wrapped

in foil)

PREPARING, DEPLOYING,

RECOVERING, AND STORING PSM

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Water Column Deployment

(NHEERL & MIT)

PE

Stainless steel ring

SPME (in copper

mesh envelope)

PE POM

(NHEERL & Brown U)

Fish trap



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Water Column Deployment



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Pore water Deployment

(SCCWRP)

Copper tubing

housing SPME (in

protective syringe)

SPME (in protective syringe) (Texas Tech U)

SPME (inside

stainless steel tube)

(Technical U Denmark)



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PE or POM (in aluminum frame)


(MIT)

PE or POM (in aluminum frame)

(MIT)



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(U Maryland Baltimore County)


POM

(in wire mesh

enclosure)

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OSRTI’s Environmental Response Team Dive Team & Region 10’s Dive Team

have extensive experience deploying and recovering passive samplers – cost-

effective resource

(MIT

& R

egio

n 9

)

Diver-assisted

sediment deployment

(United Heckathorn

Superfund Site)

Pore water

Deployment


RECOVERING, AND STORING PASSIVE

SAMPLERS

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(NHEERL )

(NH

EE

RL )

PE and POM

(in aluminum frames)

SPME in copper tubing Porewater Deployment (Palos Verdes Shelf Superfund Site)



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Raw data (from the analytical laboratory)

Measured concentration of contaminants in the passive sampler (CSampler)

• Units

– ng/g sampler

– ng/mL sampler (convert to µg/g sampler by dividing by the passive sampler density (e.g., PE = 0.92 g/mL))

Calculate contaminant freely dissolved concentration (Cfree) (ng/mL):

ANALYZING PSM DATA

freeSampler

Sampler

free K

CC

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Establishing when equilibrium between the contaminants and passive sampler occurs

Challenge in all monitoring (including biomonitoring)

Potentially expensive to determine (i.e., extra samples = $$$) • Perform time series (e.g., collect PSM weekly for 30 days)

• Compare different thicknesses of PSM

One approach: Performance Reference Compounds (PRCs) loaded into the passive sampler to predict equilibrium

• PRC is a chemical that behaves like the target COC


Co

nce

ntr

atio

n

(ng

/g P

assiv

e S

am

ple

r)

* = Equilibrium

ANALYZING PSM DATA

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Pore water

Passive Sampler

(PE, POM or SPME) Initial concentration of 13C-PCBs in

passive samplers is known

PCB (Cfree form)

13C-PCB

(used as

the PRC)

ANALYZING PSM DATA

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Concentr

ation

(ng/g

Passiv

e S

am

ple

r)

0 30

ANALYZING PSM DATA

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PCB

PRC

Magnitude of adjustment for

non-equilibrium conditions

Step 1

Step 2

First Order Method: Two Step Process

t

C

C

kf

i

PRC

PRC

e

ln

where, ke is the

exchange rate coefficient

for a given PRC, PRCi and PRCf

are the initial and final PRC

concentrations, and t is the

deployment duration

freeSampler

Sampler

free K

CC

tk

freeSampler

Sampler

free eeK

CC

1*

Deployment Time (d)

Concentr

ation

(ng/g

passiv

e s

am

ple

r)

ANALYZING PSM DATA

Two other methods:

- Diffusion-based

- Rate of PRC diffusion through polymer is used to determine

magnitude of disequilibrium correction for target contaminants

- Exchange rate-based

- PRC data used to calculate disequilibrium-corrected exchange rates

for target contaminants

- Both methods are very calculation intensive and are available on

computer-based graphical-user interfaces (GUIs) or spreadsheets

- GUIs available on-line

- Superfund website

- SERDP/ESTCP websites

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Measuring COC bioavailability

Using PSM as surrogates for organism bioaccumulation

Bioavailability assessments:

Passive Sampler (e.g., POM,

PE or SPME)

?

= Blue Mussels Benthic Worms

EVALUATING PSM APPLICATIONS

Friedman et al. (2009)

Bioaccumulation = 0.948*PSM Uptake + 1615

r2 = 0.88

n = 48

New Bedford Harbor Superfund Site

(Laboratory deployment)

Burgess et al. (2015) Joyce et al. (2016)

► When applied properly, passive sampling based

estimates of bioaccumulation may provide useful

information for making informed decisions about the

bioavailability of COCs in aquatic environments

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Determining COC Flux

Using PSM to measure transport of COCs between sediments and water column


Sediment & Pore water

Water Column

De

pth

(cm

)

20

15

10

5

-5

-10

-15

-20

Sediment & Pore water

Water Column

Magnitude of transfer

to water column

Cap effectiveness Cap

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Recover passive sampler


1

3

2

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(NHEERL )

(NH

EE

RL )

Platform when deployed


Flux = 260 ng

p,p’-DDE/cm2 y

Superfund Sites:

Palos Verdes Shelf (Region 9)*

Lower Duwamish Waterway

(Region 10)

Grasse River (Region 2)

Dover Gas Light (Region 3)

Palos Verdes Shelf Superfund Site

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Derived from

Passive Sampling

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Passive sampling provides data on: Freely dissolved concentrations (Cfree) of COCs

- Effective surrogate for bioavailable contaminant concentrations

Concentration of COCs in the passive sampler Approach operates based on the well-understood principles of equilibrium

partitioning and sampling

Preparation, deployment, recovery and storage are no more complicated than current contaminant sampling methods Possibly greater scientifically-robustness, logistically simpler, and more

cost-effective

Applications Assessing COC bioavailability Measuring COC fluxes Developing Pore Water Remedial Goals (PWRGs)

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SUMMARY

√

√

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Useful documents https://semspub.epa.gov/work/HQ/175405.pdf (2012)

http://www.epa.gov/nheerl/download_files/publications/

RB%20ESB%202012final_2.pdf (2012)

Society of Environmental Toxicology and Chemistry journal:

Integrated Environmental Assessment and Management

2014 Series (Six papers on passive sampling) (2014)

https://semspub.epa.gov/work/HQ/100000146.pdf (2017)

https://semspub.epa.gov/work/HQ/100000539.pdf (2017)df

SUMMARY

EPA/600/R-16/357

Laboratory, Field, and Analytical Procedures for Using Passive Sampling in the Evaluation of Contaminated Sediments: User’s Manual

February 2017 Final Web Version (1.0)

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http://www.epa.gov/nheerl/download_files/publications/

passive sampling for measuring freely dissolved ......passive sampler (c sampler) •units –ng/g...

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