NEW ADVANCES IN PASSIVE SAMPLING FOR SEDIMENT RISK

ASSESSMENT

Upal GhoshDepartment of Chemical, Biochemical, & Environmental Engineering

UMBC

SETAC HDCOct 7, 2015

Legacy contaminants in exposed sediment contaminates the food chain through:

1) bioaccumulation in benthic organisms

2) flux into the water column, and uptake in the pelagic food web.

Contaminated sediment

1

Bioaccumulation of Hydrophobic Compounds

• Predictions work reasonably well for natural systems

• Predictions become more challenging for industrially impacted sediments

3

2 L water

100g fish

0.0002 mg DDD

1.7 mg DDD

Sediment1 ppm Koc = 151,000

Large fish1.7 ppm

Small fish0.5 ppm

Plankton0.0265 ppm

Water0.0001 ppm

Bioaccumulation And Exposure of DDD

Ehlers and Luthy, ES&T 2003

Measurement of HOCs in Water is Challenging

Need to measure <ng/L concentrations in sediment porewater

Two approaches to get to this concentration:

1) Modeling based on partitioning calculations:A) Sediment concentration and fraction OCB) Model presumes a certain partitioning behavior for the OCC) Complication from the presence of BCD) Difficult to characterize BC partitioning

2) Direct measurement:A) Detection limits associated with manageable grab samplingB) Separation of colloids challengingC) Passive sampling

Carbon Type Influences PAH Partitioning in MGP Sediments

• Red line shows predicted Koc based on NOM partitioning

• Measured Koc higher by two orders of magnitude

• PAH association with coal, coke, pitch, or soot increases observed Koc

Pyrene

4

5

6

7

8

HD

-3

HD

-5

HD

-6

NY

-5

NY

-18

TR

-12

TR

-15

Milw

auke

e H

arbo

r

Har

bor

Pt.

CA

-10

CA

-17

CA

-18

CA

-2

CA

-5

Me

as

ure

d lo

g(K

oc

)

7

Organic Carbon Types in Soil/Sediment• Sediment contains sand, silt, clays,

charcoal, wood, char, coal, & shells• PCBs/PAHs bound to carbonaceous

particles less bioavailable

charcoal

coal

sand

wood

shell

char

Petrography images

coal charcoal coke

0

1

2

3

4

5

6

7

activ

ated

carb

on

soot

carb

on

parti

culat

e co

al

parti

culat

e ch

arcoa

l

heav

y fue

l oil

coal

tar

Pula

kero

gen

colla

gen

hum

ic acid

degr

aded

alga

e

amor

phou

s org

anic m

atter

oxidi

zed

hum

ic acid

cutic

lealg

aelig

nin

cellu

lose

seve

ral s

oils a

nd se

dimen

t

log

(Koc

)

Phenanthrene partitioning for various organic materials

From: Ghosh et al. Environ. Sci. Technol. 2003

1) Hydrophobic chemicals partition among the aqueous and different solid phases

2) Equilibrium distribution can be described by: Freely dissolved

Passive sampler

DO

C

POCTwo approaches to measure total

and freely dissolved concentrations:

1) Remove POC by centrifugation, measure total dissolved concentration and DOC, estimate freely dissolved concentration.

2) Use calibrated passive sampler to measure freely dissolved concentration, measure DOC/POC, and estimate total dissolved concentration.

Conceptual Understanding of Passive Sampling:

Ctotal = Cfree + DOC*KDOC*Cfree + POC*KPOC*Cfree

PAH & PCB Uptake Kinetics in Well Mixed Batch

Hawthorne et al. Analytical Chem. 2009 & 2011

• Under well-mixed conditions POM, PE, or PDMS reaches close to equilibrium in <30 days

• Used to measure site-specific partition constants

10

Polymer Partition Constants

PDMSPAH: logKPDMS-w = 0.725logKow + 0.479 (R2 = 0.99)PCB: logKPDMS-w = 0.947logKow – 0.017 (R2 = 0.89)

POLYETHYLENEPAH: logKPE-w = 1.22logKow – 1.36 (R2 = 0.99)PCB: logKPE-w = 1.18logKow – 1.26 (R2 = 0.95)

POLYOXYMETHYLENEPAH: logKPOM-w = 0.839logKow + 0.314 (R2 = 0.97)PCB: logKPOM-w = 0.791logKow + 1.02 (R2 = 0.95)

• The most important parameter necessary for calibration is Kpw• Accurate measurement of Kpw for high Kow compounds is

challenging• A list of provisional Kpw values are available in Ghosh et al. 2014

Common polymers : Polyethylene (PE), Polyoxymethylene (POM) and Polydimethylsiloxane (PDMS)

11

• Practical guidance on the use of passive sampling methods (PSMs) for Cfree for improved exposure assessment of hydrophobic organic chemicals in sediments.

• Based on SETAC Technical Workshop “Guidance on Passive Sampling Methods to Improve Management of Contaminated Sediments,” 2012

Practical Guidance for Passive Sampling

Passive sampler uptake slow in static field deployments

12

𝑪𝒘=¿ ¿¿

Polymer-water partitioning coefficient

United States Environmental Protection Agency. (2012, Dec). Guidelines for using passive samplers to monitor organic contaminants at superfund sediment sites

Diffusive Process of HOCs Into Polymers

• First order mass transfer models=

13

CpKu Ke

CwCw

𝐾 𝑝𝑤 • A function of overall mass transfer coefficient

• Dissipation of Performance Reference Compounds

X

Cw Cw

Cp• Diffusion based models

(𝜀+𝜌 𝐾 𝑑)𝛿𝐶𝑤

𝛿𝑡=𝐷

𝛿2𝐶𝑤

𝛿𝑥2

Dp =Diffusion coefficient in polymer, ε = porosity, ρ = particle bulk density D = effective diffusion coefficient, Kd= sediment-water partitioning coefficient

14

Tracking pyrene diffusion with Fluorescence

PE/POM rod in Saturated Pyrene solution

Aluminum foil

Flu

ores

cen

ce in

ten

sity

Distance (mm)

Fluorescence image of polymer slice

Cut

0 1 2 3 4 5 6 70

2

4

6

f(x) = 0.660246633079289 x + 0.920257035396337R² = 0.997662762312603

Pyrene mass (pg)

Flu

ores

cen

ce i

nte

nsi

ty

15

Pyrene diffusion into PE (static)

Sediment side poly

mer

Performance Reference Compounds• Equilibrium slow for: 1) high Kow; 2) static porewater

• Mass transfer in sediment side difficult to predict

• Performance Reference Compounds (PRCs) are used to correct for non-equilibrium

• PRCs have similar diffusion properties as analytes

16

0 30 600

0.5

1

Analyte

PRC

Analyte ad-sorption

PRC des-orption

Pas

sive

sam

pler

Time (days)

Poly

mer

fracti

on

al

up

take

𝐶𝑝=𝐾 𝑝𝑤𝐶𝑤 [1 −𝑒𝑥𝑝 (−𝑘𝑒𝑡 ) ]

𝑘𝑒=−ln (𝐶𝑃𝑅𝐶 , 𝑓 /𝐶𝑃𝑅𝐶 ,𝑖)

𝑡

Limitations of PRC-correction methods• Low fractional loss of high molecular weight PRCs• Extrapolation from low molecular weight PRCs difficult:

17

Loss of low molecular weight

PRCs

Cfree High molecular weight

analytes

Adjustment methods

Inaccurate for high molecular weights

Diffusion model & Kd-Kow correlation2

1st order model & molar volume

correlation1

1- Booij, K.; Hoedemaker, J. R.; Bakker, J. F. Environ. Sci. Technol. 2003, 37 (18), 4213–42202-Fernandez, L. A., C. F. Harvey, and P. M. Gschwend, 2009a. Environmental Science & Technology, v. 43, p. 8888-8894.

How Do You Use Freely Dissolved Concentrations in Porewater (Cfree) ?

DO NOT: Call it : Bioavailable concentration or Bioavailable fraction

• Need a robust toxicity or biouptake model to plug in Cfree

• For PAHs: Can plug directly into toxic units calculation based on the narcosis model

• For other bioaccumulative compounds need to plug into a bioaccumulation model

Examples in last talk by Huan Xia

1) Ex-situ equilibrium measurements of sediment porewater

2) In-situ probing to assess ambient contaminant concentrations or to assess changes with time or with treatment

Pictures of typical applications:

sediment

water

Applications of Passive Sampling

Laboratory batch equilibrium

Field evaluation of treatment performance

Depth profiling of porewater conc. in sediment

Passive sampling of porewater and in-situ bioaccumulation

Tool for inserting passive sampler frame in sediment. The 8’ pole allows deployment from a boat in shallow water sediments

Passive sampler encased in stainless steel mesh and framed for sediment deployment

Underwater video camera for confirming placement depth

Rope and buoy for retrieval after deployment

Deployment Device For Inserting Passive Sampler Frame Into Surface Sediments

Image from underwater camera showing the passive sampler being inserted into sediment

0

20

40

60

80

100

120

1 10 100 1000 10000

Nontoxic Sediment

Toxic Sediment

Sediment Total PAH Concentration (mg/kg)

Perc

ent S

urvi

val (

%)

0

20

40

60

80

100

120

0.001 0.01 0.1 1 10 100

Nontoxic Sediment

Toxic Sediment

SPME Pore Water PAH Conc. (moles/L)

Sur

viva

l (%

)

NONTOXIC TOXIC

Figure 1. Chronic toxicity to H. azteca (28-day) can not be predicted from total PAH

concentration in MGP sediment

Figure 2. Chronic toxicity to H. azteca (28-day) can be predicted by estimating PAHs in

sediment pore water.

Prediction of Toxicity:Sediment vs. Freely Dissolved Conc.

Kreitinger et al , ETC 2007

Prediction of Biouptake in benthic organisms:Sediment vs. Freely Dissolved Conc.

• 7 freshwater and marine sediments• Freely dissolved conc. measured by passive sampling and also directly• Lipid concentrations better predicted from freely dissolved porewater

Werner et al. ES&T 2010

Predicted from sediment Predicted from porewater

Sediment

Passive samplers

Water flow in aquaria tanks

Components in each aquaria

• Treatments: Clean sediment (Rhode River)PCB impacted sediment (Near-shore Grasse River)PCB impacted sediment-AC treated in the lab

• Replicate aquaria with passive samplers in water column and sediment

• Fish species: Zebrafish• PCB-free diet• Sampling after 45 and 90 days

23

Prediction of PCB Uptake in Fish

Fadaei et al. ES&T 2015

24

Sediment Partitioning Coefficient Predictions

Schwarzenbach et al. 2003 Werner et al. 2009

25

• The total PCB concentration in fish was decreased by 87% after treatment with AC

PCB Residue in Zebrafish after 90 Days

Steady-State Approach

≈

Kinetic Approach

26

k1

k2ke

Predicting PCB Uptake in Fish

= - (+)

= (Arnot and Gobas 2004)

Observed and predicted PCB concentrations in fish

Equilibrium model Kinetic model with ingestion

ACKNOWLEDGMENTS

• Funding support from SERDP/ESTCP programs, NIEHS, USEPA GLNPO, and Alcoa

• Several students and post docs

KEY MESSAGES

• Freely dissolved concentrations of HOCs good predictor of biouptake and toxicity

• Passive samplers can accurately measure freely dissolved concentrations at equilibrium

• Corrections needed for non-equilibrium for in-situ measurements

30

Extraction Device

also containing a lipid source (sunflower oil) to mimic the lipophilic environment

Phase one: acidic gastric condition

Phase two: near-neutral intestinal condition

Simulated gastrointestinal fluid

CARBON TYPE ALSO INFLUENCES PAH BIOAVAILABILITY IN ANIMAL GUT

SERDP FUNDED STUDY

31

COMPARISON BETWEEN SOIL KD & BIOACCESSIBILITY

4 5 6 7 8 90.0

0.3

0.6

0.9

1.2

1.5

solvent spiked soil

Exponential (solvent spiked soil)

Benzo(a)pyrene

log KD

Bio

accessib

le F

rac-

tio

nn=30

BACKGROUND ON ESB GUIDANCE (2003, 2008)

• ESBs are based on a target lipid model (Di Toro et al. 2000)

• Developed critical lipid concentrations for 49 aquatic species

• 5th percentile expected to be protective of95 percent of species tested

Gen

us M

ean

Acut

e Va

lue

(mm

ol/g

oct

anol

)

Percentage Rank of Genera

TIERED ASSESSMENT

PAH AND PCB ABSORPTION EFFICIENCY IN CLAMS

From: McLeod et al. Environ. Sci. Technol. 2004

•Tracking 3H-BaP and 14C-2,2’,5,5’ PCB through a clam

ESB GUIDANCES (2008, 2005)