Delaware River Basin Commission

Role of Sediments in Managing PCBs in the Delaware Estuary

Gregory J. Cavallo, P.G.Thomas J. Fikslin, Ph.D.

NJ Monitoring CouncilSeptember 21, 2016

Why sample sediment?

PCBs concentrations from the Delaware Estuary collected for the Delaware Estuary Benthic Inventory (DEBI) project (2008) and DRBC efforts in 2010

Compare PCB homolog signatures

Technical/Management Implications

Discuss 2016 Sediment Sampling Effort

Presentation Outline

Roles of Sediment

Interaction with water columnMediating the water column response

Integrator of changes in water column concentrations

Provide data on trends

Providing assimilation capacity

Pollutant removal mechanism

Why Sample Sediments?

Principal Mass Loadings and Fluxes

Contaminated Site Loads

Upstream Boundary Load

Delaware River at Trenton, NJ

Sediment

Flux

Atmoshpheric

Wet / Dry

Deposition

Atmoshpheric

Gas phase

flux

Upstream Boundary Load

Schuylkill River

Non-Point Source LoadsTributary Loads

Point Discharge Loads

Sediment

C&D Canal

(tidal boundary)

Ocean Boundary

Mouth of Delaware Bay

CSOs

LEGEND

External Loads

(forcing functions)

Fluxes and tidal boundaries

Past and current PCB loadings of PCBs result in the accumulation of contaminated sediment.

Even if current loadings are substantially reduced, the water column will not immediately respond due to contributions of PCBs from the sediment.

As clean sediments enter the water body, sediment concentrations will ultimately be in equilibrium with the water column concentrations.

Mediating Water Column Response

Current PCB Loading Condition

10

100

1000

10000

2016 2026 2036 2046 2056 2066 2076 2086 2096 2106 2116

To

tal P

CB

co

nce

ntr

ati

on

(p

g/L

)

Years

Projected, median Total PCB concentrations (Penta Homolog Model)Four BCs and loads @ current condition ; with current Sediment & Water Column

Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 PCB WQC (16 pg/L)

Effect of Sediment Flux

0.01

0.1

1

10

100

1000

10000

2016 2026 2036 2046 2056 2066 2076 2086 2096 2106 2116

Tota

l PC

B c

on

cen

trat

ion

(pg/

L)

Years

Projected, median Total PCB concentrations (Penta Homolog Model)4 BCs and external loads @ zero; Sediment & Water column @ current Conc.

Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 PCB WQC (16 pg/L)

Sediment samples were collected as part of the Delaware Estuary Benthic Inventory (DEBI) Program in Summer of 2008

Surface grab samples

Young stainless steel grab

187 samples were received by the DRBC

Samples were collected in Zones 4, 5 and 6with an emphasis in Zones 5 and 6

DEBI Sediment Sample Collection

52 samples were analyzed for PCBs

4 samples analyzed were from Zone 4

34 samples analyzed were from Zone 5

14 samples analyzed were from Zone 6

PCB samples were analyzed for all 209 congeners using EPA Method 1668 revision A by Axys Analytical Laboratories

Analytical results are provided in pg/g dry weight

Estimated Detection Limits of <1 pg/g (ppt)

90% of all congeners detected

PCB Analysis

Total PCB Concentrations pg/g

(ppt) dry weight

PCB Homolog Distribution upper Zone 5

PCB Homolog Distribution Zone 4

Nona and deca concentrations represent > 90% of all PCBs

mono

di

tri

tetra

penta

hexa

hepta

octa

nona

deca

PCBHomologs

PCB Homolog Distribution Lower Zone 5

PCB Homolog Distribution Zone 6

Prominent

deca

signature

DEBI effort extended to Zone 2, 3 and upper Zone 4

29 additional samples were collected and analyzed for PCBs 11 samples collected in Zone 4 9 samples collected in Zone 3 9 samples collected in Zone 2

PCB samples were analyzed for all 209 congeners using EPA Method 1668 revision A by Axys Analytical Laboratories

Additional Samples collected in 2010

DEBI 2008 Samples

DRBC 2010 Samples

DRBC Samples Collected in 2010

Samples collected in 2008 and 2010

Comparison of PCB Concentrations

Phila

delp

hia

Pa.

Wilm

ingto

n

De.

Tre

nto

n N

J.

ppb

Current and expected penta-PCB concentrations in sediment layer when the TMDLs

are achieved

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

0 20 40 60 80 100 120 140

River Mile

Co

cen

tra

tio

n,

mg

/L

Current_Sediment_PCB Concentration Sediment_PCB_Concentration after TMDLs

Zone 6 Zone 5 Zone 4 Zone 3 Zone 2

pp

m

2016 SedimentSampling Locations

11/7/2016

DRBC Staff Sediment Sampling

QUESTIONS?