Upal Ghosh Department of Chemical Biochemical amp Environmental Engineering UMBC SETAC HDC Oct 7 2015 Legacy contaminants in exposed sediment contaminates the food chain through ID: 408831
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NEW ADVANCES IN PASSIVE SAMPLING FOR SEDIMENT RISK ASSESSMENTUpal GhoshDepartment of Chemical, Biochemical, & Environmental Engineering UMBC
SETAC HDCOct 7, 2015Slide2
Legacy contaminants in exposed sediment contaminates the food chain through: bioaccumulation in benthic organismsflux into the water column, and uptake in the pelagic food web.Contaminated sediment
1
Bioaccumulation of Hydrophobic Compounds
P
redictions work reasonably well for natural systems
Predictions become more challenging for industrially impacted sedimentsSlide3
3
2 L water
100g fish
0.0002
mg DDD
1.7
mg DDD
Sediment
1 ppm
K
oc
= 151,000
Large fish
1.7 ppm
Small fish
0.5 ppm
Plankton
0.0265 ppm
Water
0.0001 ppm
Bioaccumulation And Exposure of DDDSlide4
Ehlers and Luthy, ES&T 2003Slide5
Measurement of HOCs in
Water
is
Challenging
Need to measure <ng/L concentrations in sediment
porewater
Two approaches to get to this concentration:Modeling based on partitioning calculations:Sediment concentration and fraction OCModel presumes a certain partitioning behavior for the OCComplication from the presence of BCDifficult to characterize BC partitioning
Direct measurement:Detection limits associated with manageable grab samplingSeparation of colloids challengingPassive samplingSlide6
Carbon Type Influences PAH Partitioning in MGP SedimentsRed line shows predicted Koc based on NOM partitioningMeasured Koc higher by two orders of magnitudePAH association with coal, coke, pitch, or soot increases observed KocSlide7
7Organic Carbon Types in Soil/SedimentSediment contains sand, silt, clays, charcoal, wood, char, coal, & shellsPCBs/PAHs bound to carbonaceous particles less bioavailable
charcoal
coal
sand
wood
shell
char
Petrography images
coal
charcoal
coke
Phenanthrene
partitioning for various organic materials
From:
Ghosh
et al. Environ. Sci. Technol. 2003Slide8
Hydrophobic chemicals partition among the aqueous and different solid phases
Equilibrium distribution can be described by:
Freely dissolved
Passive sampler
DOC
POC
Two approaches to measure total and freely dissolved concentrations:
Remove POC by centrifugation, measure total dissolved concentration and DOC, estimate freely dissolved concentration.
Use calibrated passive sampler to measure freely dissolved concentration, measure DOC/POC, and estimate total dissolved concentration.
Conceptual Understanding of Passive Sampling:
C
total
=
C
free + DOC*KDOC*Cfree + POC*KPOC*CfreeSlide9
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 constantsSlide10
10Polymer Partition Constants
PDMS
PAH:
log
K
PDMS
-w
= 0.725
log
K
ow
+ 0.479 (
R
2
= 0.99)PCB: logKPDMS-w
= 0.947logKow – 0.017 (R2 = 0.89)POLYETHYLENE
PAH: logKPE-w = 1.22logKow – 1.36 (R2
= 0.99)PCB: logKPE-w = 1.18logKow – 1.26 (R
2 = 0.95)POLYOXYMETHYLENEPAH: logKPOM-w
= 0.839logK
ow + 0.314 (R
2 = 0.97)
PCB: logKPOM-w = 0.791logKow + 1.02 (R2 = 0.95)
The most important parameter necessary for calibration is KpwAccurate measurement of Kpw
for high Kow compounds is challengingA list of provisional Kpw values are available in Ghosh et al. 2014
Common polymers : Polyethylene (PE), Polyoxymethylene (POM) and Polydimethylsiloxane (PDMS)Slide11
11Practical 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
,” 2012Practical Guidance for Passive SamplingSlide12
Passive sampler uptake slow in static field deployments12
Polymer-water partitioning coefficient
United States Environmental Protection Agency. (
2012, Dec).
Guidelines for using passive samplers to monitor organic contaminants at superfund sediment sitesSlide13
Diffusive Process of HOCs Into PolymersFirst order mass transfer models
=
13
Cp
Ku
Ke
Cw
Cw
A function of overall mass transfer coefficient
Dissipation of Performance Reference Compounds
X
Cw
Cw
Cp
Diffusion
based models
D
p
=Diffusion coefficient in polymer, ε = porosity, ρ = particle bulk density D = effective diffusion coefficient, Kd= sediment-water partitioning coefficientSlide14
Tracking pyrene diffusion with Fluorescence 14
PE/POM rod in Saturated Pyrene solution
Aluminum foil
Fluorescence intensity
Distance (mm)
Fluorescence image of polymer slice
CutSlide15
15
Pyrene diffusion into PE (static
)
Sediment side
polymerSlide16
Performance Reference CompoundsEquilibrium slow for: 1) high Kow; 2) static porewaterMass 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
Passive sampler
Time (days)
Polymer fractional uptake
Slide17
Limitations of PRC-correction methodsLow fractional loss of high molecular weight PRCsExtrapolation from low molecular weight PRCs difficult: 17Loss of low molecular weight PRCs
Cfree High molecular weight analytes
Adjustment methods
Inaccurate for high molecular weights
Diffusion model & K
d
-
K
ow
correlation
2
1
st
order model & molar volume correlation
11- 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.Slide18
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
C
freeFor PAHs: Can plug directly into toxic units calculation based on the narcosis modelFor other bioaccumulative compounds need to plug into a bioaccumulation modelExamples in last talk by Huan XiaSlide19
Ex-situ equilibrium measurements of sediment porewaterIn-situ probing to assess ambient contaminant concentrations or to assess changes with time or with treatmentPictures 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 bioaccumulationSlide20
Tool for inserting passive sampler frame in sediment. The 8’ pole allows deployment from a boat in shallow water sedimentsPassive sampler encased in stainless steel mesh and framed for sediment deploymentUnderwater 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 Slide21
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 2007Slide22
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 sedimentPredicted from porewaterSlide23
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 sedimentFish species: ZebrafishPCB-free diet
Sampling after 45 and 90 days23Prediction of PCB Uptake in FishFadaei et al. ES&T 2015Slide24
24Sediment Partitioning Coefficient Predictions
Schwarzenbach
et al. 2003
Werner et al. 2009
Slide25
The total PCB concentration in fish was decreased by 87% after treatment with AC25PCB Residue in Zebrafish
after 90 DaysSlide26
Steady-State Approach
≈
Kinetic
Approach
26
k
1
k
2
k
e
Predicting PCB Uptake in Fish
=
- (
+
)
=
(
Arnot
and
Gobas 2004)Slide27
Observed and predicted PCB concentrations in fishEquilibrium modelKinetic model
with ingestionSlide28
ACKNOWLEDGMENTSFunding support from SERDP/ESTCP programs, NIEHS, USEPA GLNPO, and AlcoaSeveral 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 equilibriumCorrections needed for non-equilibrium for in-situ measurementsSlide29Slide30
30
Extraction Device
a
lso 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 STUDYSlide31
31COMPARISON BETWEEN SOIL KD & BIOACCESSIBILITYSlide32
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
Genus Mean Acute Value (mmol/g octanol)
Percentage Rank of GeneraSlide33
TIERED ASSESSMENTSlide34
PAH AND PCB ABSORPTION EFFICIENCY IN CLAMSFrom: McLeod et al. Environ. Sci. Technol. 2004
Tracking 3H-BaP and 14C-2,2’,5,5’ PCB through a clamSlide35
ESB GUIDANCES (2008, 2005)