1

Partitioning and Bioavailability Assessment for Sediments from

South Wilmington Wetlands

Huan Xia and Upal Ghosh

Department of Chemical, Biochemical, and Environmental EngineeringUniversity of Maryland, Baltimore County

2

Location

27-acre degraded wetlandContaminants detected in marsh soil: Metals (e.g. As, Pb, Cr) PAHs (e.g. Benzo(a)pyrene,

Benzo(k)fluoranthene) PCBs such as Arochlor-1248

(Hendershot and Asreen Jr. 2005)

3

Introduction Hydrophobic organic compounds (HOCs) like PCBs and PAHs strongly

bound to sediment geochemical components

Some carbonaceous particles (e.g. soot and charcoal) exhibit greater sorption capacity than organic matter, resulting in reduced exposure

Traditional risk assessment uses default values from generic organic matter

Site specific values can be orders of magnitude different from default values

EPA recommends using site specific measurement of partition constants to refine the risk assessment

Sediment samples collected from 12 locations of wetland.

Measurement of PAH and PCB concentrations in sediment samples.

Laboratory partitioning study to measure PAH and PCB porewater concentrations using Polyethylene (PE) as passive sampler

5 PRCs used to correct for equilibrium porewater concentration

Laboratory bioaccumulation study for PCBs using Lumbriculus variegatus

Study Objectives:Evaluate site specific bioavailability of PAHs and PCBs in South Wilmington Wetland sediment and refine risk assessment.

Methods

4

Results: Total PAH and PCB concentrations in sediments

13301334

1334 duplicate

1356HA47

HA52

HA62 2'-4'

HA62 4'-6'HA64

HA67HA70

GP19GP46

GP46 duplicate

sed 01

sed 02

sed 03

0

10

20

30

40

50

Tot

al c

once

ntr

atio

n (

mg/

kg)

Sediment total PAH concentrations

13301334

1334 duplicate

1356HA47

HA52

HA62 2'-4'

HA62 4'-6'HA64

HA67HA70

GP19GP46

GP46 duplicate

sed 01

sed 02

sed 03

0.00.51.01.52.02.53.03.54.04.55.0

Sediment total PCB concentrations

Tota

l con

cent

ratio

n (m

g/kg

)

Total PAH range from 0-40 mg/kg , mean value: 12 mg/kg

Total PCB range from 0-4.6 mg/kg , mean value :0.7 mg/kg

5

Total Equilibrium porewater concentrations of PAHs & PCBs

13301334

HA47HA52

HA64HA67

GP19GP46

SED01

SED02U

SED02T

SED03U

SED03T

0

200

400

600

800

1000

1200

1400

1600Total PAH porewater concentration

pore

wat

er c

once

ntra

tion

(ng

/L)

The highest PAH porewater concentration was measured in Sed01.

Sed02 and Sed03 were amended with 5% activated carbon to evaluate the effect of the carbon treatment, named as Sed02T and Sed03T. “U” refers to “untreated”.

70% to 90% reduction in PAH porewater concentration observed in treated samples 6

7

The highest total PCB porewater concentration was measured in Sed02U, Sed03U and 1330.

80% to 90% reduction in PCB porewater concentration also observed in treated samples

Site specific organic partition constants : Koc= Cs/Cw/foc

13301334

HA47HA52

HA64HA67

GP19GP46

SED01

SED02U

SED02T

SED03U

SED03T

0

20

40

60

80

100

120

140

160

180 Total PCB porewater concentration

pore

wat

er c

once

ntra

tion

(ng

/L)

Total Equilibrium porewater concentrations of PAHs & PCBs

8

Bioaccumulation of PCBs in Lumbriculus variegatus

13301334

HA47HA52

HA64HA67

GP19GP46

Sed01

Sed02U

Sed02T

Sed03U

Sed03T

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5Mono Di Tri Tetra Penta Hexa Hepta Octa Nona Deca

PCB

conc

entr

ation

in w

orm

(ug/

g w

et w

eigh

t)

Worm recovery ranges from 50- 70%.

The highest bioaccumulations in worms were in samples 1330, Sed03 and Sed02, which also had the highest PCB levels in sediment.

Reduction in PCB bioaccumulation was 97-98% in treated samples

13301334

1334 duplicate

1356HA47

HA52

HA62 2'-4'

HA62 4'-6'

HA64HA67

HA70GP19

GP46

GP46 duplicate

sed 01

sed 02

sed 03

0.0

1.0

2.0

3.0

4.0

5.0

Sediment total PCB concentrations

Tota

l con

cent

ratio

n (m

g/kg

)

partition constants for PAHs and PCBs

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.02.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

f(x) = 0.726249870420338 x + 3.05688443657461R² = 0.91811655432422

correlation from KarickhoffKoc from initial PRG reportLinear (Koc from initial PRG report)Koc from site measurement

log

Koc

log Kow

PAHs

4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.53.0

4.0

5.0

6.0

7.0

8.0

9.0

f(x) = 0.798832694674654 x + 1.01630938563259R² = 0.779317749085989

PCBs

Koc from site measurement

log Kow

Measured Koc values for both PAHs and PCBs were 1-2 orders of magnitude higher than the generic values used in preliminary risk assessments

Median value of BC/OC ratio : 9%, n=300 (Cornelissen et al. 2005) Measured BC/OC ratio: 17-36%

Karickoff 1981, Werner et al 2010 9Human Health Risk Assessment Protocol, 2012

10

PCB Bioaccumulation Factors (BCF) in worms

BCF calculated as: BCF= Clipid/Cporewater

Measured BCF (blue diamonds) are consistent with the generic values (green dash), but nearly 1 order of magnitude higher than those in initial PRG (red dash)

log BCF= 0.819 log Kow- 1.146

5.0 5.5 6.0 6.5 7.0 7.52.0

3.0

4.0

5.0

6.0

7.0

f(x) = 0.7554302381643 x − 0.0626054285367292R² = 0.783654505474392

Correlation from measured dataLinear (Correlation from measured data)Correlation from Werner 2010

log Kow

log

BCF

log BCF VS. log Kow

EPA. (1999). Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities

11

Calculation for Preliminary Remediation Goals (PRGs)

Benthic organism-based PRGs (Equilibrium Partitioning Approach):

PRGsediment = Toxicity Value × foc × Koc

• PRG, concentration in sediment (mg/kg DW sediment)

• Toxicity Value , Aquatic community-based toxicity value (μg/L)

• foc, Organic carbon fraction (2 % default used in initial calculation, average of 4% TOC was detected in sediments )

• Koc, Organic carbon partition constants (default value from HHRAP used in initial calculation, measured specific Koc used in revised version)

Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: PAH Mixtures (EPA, 2003e)

Revised Benthic Organism-based PRGs using site specific Koc

12

1E-04 1E-03 1E-02 1E-01 1E+00 1E+01 1E+02 1E+03 1E+041E-04

1E-03

1E-02

1E-01

1E+00

1E+01

1E+02

1E+03

1E+04

PAHPes-ti-cidesPCB

Initial sediment PRG (mg/kg DW)

Revi

sed

sedi

men

t PRG

(mg/

kg D

W)

Based on exposure to benthic organisms

Human Health Risk Assessment Protocol, 2012

Calculation for Preliminary Remediation Goals (PRGs)

PRGs based on invertebrate –based food web modeling: (bioamagnification and trophic transfer through dietary exposure)

PRGsediment=

(Ecological Sediment Screening Level, EPA 2007a, 1999, 1993)

Local receptors: American robin, Raccoon, Spotted sandpiper, etc. Spotted sandpiper was selected due to its most rigid sediment

concentration criteria. 13

Revised PRGs based on exposure to Spotted Sandpiper

14

1E-06 1E-05 1E-04 1E-03 1E-02 1E-01 1E+00 1E+01 1E+02 1E+03 1E+04 1E+051E-06

1E-05

1E-04

1E-03

1E-02

1E-01

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

PAHPes-ti-cidesPCB

Initial sediment PRG (mg/kg DW)

Revi

sed

sedi

men

t PRG

(mg/

kg D

W)

Based on exposure to spotted sandpiper

15

Conclusions

Observed site specific Koc values were higher than generic values derived from organic matter, mainly due to elevated black carbon in sediment

BCF measures in good agreement with literature values

PCB bioaccumulation is explained well by porewater data

Site specific measurements provided realistic parameters to refine the remediation goals

16

Acknowledgements

City of Wilmington, DelawareBrightfields Inc.

Labmates for worm retrieval

Correction based on different properties: diffusivity, partitioning coefficient, molar volume

Molar volume adjustment

• Calculate residual PRC in PE:

• Exchange rate (for PRC) :

• Sampling rate (for PRC) :

• =

• , PE sampler partition coefficient; mass of PE sampler; molar volume; t, exposure time (28days)

Methods

(Huckins et al 2006)

e.g. Cprc,f/Cprc,iPRC 29 31%PRC 69 43%PRC 155 81%PRC 192 91%

17

18

partition constants for PAHs and PCBs

Elevated Koc (3-4 orders of magnitude range) for PAHs previously observed from industrially impacted sites (n=117) Hawthorne et al. 2006

19

Methods

Impregnate PE sampler with PRCs

• Measured CW may not be at equilibrium

• CW corrected using Performance Reference Compounds (PRCs)

• Assume absorption = desorption

• Assume PRCs have similar properties as HOCs

• PRCs: PCB 29 (mono, di, tri), 69 (tetra, penta), 155 (hexa), 192 (hepta, octa, nona and deca groups) for PCB correction and d-10 pyrene for PAH.

• Preload PE sampler with PRCs for two week and measure initial concentration in sampler (CPRC,i)

• Add PE sampler into sediment

20

Laboratory worm bioaccumulation study for PCBs

• Species: Lumbriculus variegatus • Daily water exchange and water quality monitoring• 28 days bioaccumulation• Worm collection• Analyzed worm tissue for PCBs

Methods

Revised Benthic Organism-based PRGs using site specific KocAquatic Toxicity

Value (μg/L)SVOCs2,4-Dinitrophenol 19 NA NA NAPAHs2-Methylnaphthalene 4.7 6.01 3.99 179 0.92Acenaphthene 5.8 6.01 3.69 221 0.57Acenaphthylene 306.9 5.40 4.15 2862 87.0Anthracene 0.012 6.61 4.37 1.8 0.0056Benzo(a)anthracene 0.018 7.30 5.55 13.4 0.13Benzo(a)pyrene 0.015 7.56 5.98 20.0 0.29Carbazole NBA NA 2.88 NA NCChrysene 2.042 7.12 5.60 1007.4 16Dibenz(a,h)anthracene 0.2825 7.97 6.25 964.4 10Fluoranthene 0.04 7.07 4.69 17.5 0.039Indeno(1,2,3-cd)pyrene 0.275 7.85 6.49 714.0 17Phenanthrene 0.4 6.45 4.42 41.5 0.21Pyrene 0.025 6.94 4.83 8.05 0.034Pesticides4,4'-DDE 0.001 6.22 4.53 0.061 0.000684,4'-DDT 0.0005 6.13 5.04 0.025 0.0011Dieldrin 0.056 5.33 4.32 0.44 0.023Endrin 0.036 4.69 4.03 0.065 0.0078Endrin aldehyde 0.036 4.85 3.88 0.094 0.0055Endrin ketone 0.036 5.00 4.02 0.13 0.0075Heptachlor epoxide 0.0019 5.33 4.32 0.015 0.00079PCBsPCBs,total 0.54 5.69 6.39 9.79 26Dioxins/Furans2,3,7,8-TCDD 3.10E-09 6.45 6.59 3.22E-07 2.40E-07

Benthos-based Sediment PRG (mg/kg

DW) from initial report

log Koc (L/kg) from

AvatarCOPEC

Untreated Site specific

log Koc (L/kg )

Benthos-based Sediment PRG (mg/kg DW)

calculated with site Koc

21

Revised PRGs based on exposure to Spotted Sandpiper

SVOCs2,4-Dinitrophenol NA NA

PAHs2-Methylnaphthalene 6280 356

Acenaphthene 6010 167

Acenaphthylene 1570 346

Anthracene 7270 256

Benzo(a)anthracene 5050 360

Benzo(a)pyrene 4850 477

Carbazole NA 37

Chrysene 3500 367

Dibenz(a,h)anthracene 4120 255

Fluoranthene 8110 209

Indeno(1,2,3-cd)pyrene 3820 521

Phenanthrene 5860 288

Pyrene 7570 347

Pesticides4,4'-DDE 0.017 0.00092

4,4'-DDT 0.017 0.0036

Dieldrin 0.005 0.0014

Endrin 0.013 0.0097

Endrin aldehyde 0.013 0.0047

Endrin ketone 0.014 0.0045

gamma-Chlordane 1.61 NA

Heptachlor epoxide 0.030 0.0087

PCBs

PCBs,total 0.40 0.09

Dioxins/Furans2,3,7,8-TCDD 0.000011 0.000036

PRG Csed (mg COPEC/kg DW sediment)

NOAEL Based using site BCF

PRG Csed (mg COPEC/kg DW sediment)

NOAEL Based from initial reportCOPEC

22

23

Revised PRGs : Bentho-based Vs. Exposure to Spotted Sandpiper

SVOCs2,4-Dinitrophenol NA NA

PAHs2-Methylnaphthalene 179 6280Acenaphthene 221 6010Acenaphthylene 2862 1570Anthracene 1.8 7270Benzo(a)anthracene 13 5050Benzo(a)pyrene 20 4850Carbazole NAChrysene 1007 3500Dibenz(a,h)anthracene 964 4120Fluoranthene 18 8110Indeno(1,2,3-cd)pyrene 714 3820Phenanthrene 41 5860Pyrene 8.0 7570

Pesticides4,4'-DDE 0.061 0.0174,4'-DDT 0.025 0.017Dieldrin 0.44 0.005Endrin 0.065 0.013Endrin aldehyde 0.094 0.013Endrin ketone 0.13 0.014gamma-Chlordane 1.61Heptachlor epoxide 0.015 0.030

PCBsPCBs,total 9.8 0.40

COPECPRG Csed based on food

web modeling (NOAEL)

PRG Csed based on benthic

organism protection

24

Revised PRGs : Bentho-based Vs. Exposure to Spotted Sandpiper

1E-03 1E-02 1E-01 1E+00 1E+01 1E+02 1E+03 1E+04 1E+051E-03

1E-02

1E-01

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

PAHPes-ti-cidesPCB

Revised PRG based on spotted sandpiper (mg/kg DW)

Revi

sed

PRG

base

d on

ben

thic

org

anism

s (m

g/kg

DW

)