Edward A. Garvey, PhD, PG The Louis Berger Group, …s3.amazonaws.com/ebcne-web-content/fileadmin/pres/9-23-11/9-23-11... · The Louis Berger Group, Inc. L B G Edward A. Garvey, PhD,

The Louis Berger Group, Inc.

L

B

G

Edward A. Garvey, PhD, PG


Morristown, NJ

EBC Seminar Series

Part I: Advances in Sediment Site Characterization

September 23, 2011

Using Sediment Tracers to Identify Release

Events, Differentiate Sources, and Assess

Monitored Natural Recovery


L

B

G

Session Outline

Background on Sediments and Dating

Time Clocks and Horizon Markers

Tracer Examples

Applications

• Current Conditions

• Historical Conditions

• Estimating Natural Recovery

Conclusions

2


L

B

G

Background on Sediments and Dating

3


L

B

G

Nature of Sediment and Contamination

4

Increasing energy

Sediment is NOT wet dirt…

• It moves!

Energy changes everything

• ocean vs. lake vs. estuary vs. river

• deep water vs. shoreline

Influence of water

Solids transport

Dissolved phase transport

Partitioning and KD

Diagenesis

Understanding time of deposition

deconvolves impacts of energy


L

B

G

Begin with a Good Core!

5


L

B

G

How Do We Establish Time of Deposition?

(1)

6

Established principals for geological dating can be

applied to recent deposition as well.

Geologist’s Time Keepers (Clocks)

• Radioisotope Clocks (Isotope , half-life)

Age of the universe (Th232, 1010 yrs)

Age of the earth (U-238, 109 yrs)

Age of the dinosaurs (U/Pb, 108 yrs)

Age of the ice ages (U-234, 105 yrs, Th-230, 104 yrs)

Age of the Egyptians (C-14, 103 yrs)


L

B

G


(2) Geological Marker Horizons

• Banded Iron Formations

Appearance 3,800 My

Disappearance 1,700 My

• Fossils (trilobites) (530-250 My)

Appearance 530 My

Disappearance 250 My

• Iridium maximum

End of the dinosaurs 65 My

7


L

B

G


Environmental Geochemist’s Tools

Radioisotope Time Clocks

• Be-7 (53 days)

• Pb-210 (Excess) (22 yrs)

Horizon Markers

• Appearance of DDT (~1940)

• Bomb Radiocesium (Cs-137)

Appearance 1954

Maximum 1963

• Soda Can Tabs (1960-1975)

• Appearance of PBDEs (1970s)

• Appearance of Fluorinated Surfactants (PFOA/PFOS) -appearance 1950s,

max ~2000

• Appearance of Quaternary Ammonium Surfactant (ATMAC-22) ~1990

8


L

B

G

Beryllium-7 as a Radiotracer

Half life of 53 days

Highly particle reactive

Effective Partition Coefficient >104

Tags recently deposited sediment

Typically limited to upper 2 to 3 centimeters in

sediment

Sediments containing Be-7 are considered very

recently deposited, <1 year.

9


L

B

G

Atmospheric Production

Be-7

Sediment

Resuspension

and new solids

entering the

system

Be-7 Tidal Transport

and Redeposition

Particle Reactive

Sediment Bed

Water Column

Upland Sources

Deposition


L

B

G

Radiocesium (Cs-137) as a Marker Horizon

11


L

B

G

CESIUM-137 CORE DATING

Three Deposition Rate Formulas:

Dep

th

1963 Peak

1954 Appearance

Cesium-137 (pCi/g)

2005, year of

collection

Rate 3 = Depth of Appearance –Depth of Peak

(1963– 1954)

3

Ideally the

same rate

Ideally the

same rate

Rate 2 = Depth of Cs137 Peak

(Time of core collection – 1963)

2

Rate 1 = Depth of Cs137 Appearance

(Time of core collection – 1954)

1


L

B

G

Cs-137 Dated Sediment Cores from the

Hudson River

13


L

B

G

Chemical Marker Examples

DDT first appearance circa 1940

Fluorinated Surfactants (PFOA/PFOS)-appearance

1950s, max ~2000

PBDE first appearance circa 1978, max 2000 to

present

PBB first appearance circa 1970, max 1980, decline

to present

Appearance of Quaternary Ammonium Surfactant

22 (ATMAC-22) ~1990

14


L

B

G

Chemical Marker Examples

15

Poly Brominated Diphenyl Ethers Poly Brominated Biphenyls

From Zhu, et al., 2005

PBB-153


L

B

G

Quaternary Ammonium Surfactants

ATMAC 22 provides an indicator of post 1990

deposition

16


L

B

G

Idealized

Dated Core

17

Excess

Pb-210

Concentration

Dep

th

Year of collection

1 Year prior

1990

Cs-137

1963

1954

1978


L

B

G

Limitations of Sediment Dating

18


L

B

G

Use of Beryllium-7 to Identify Current Spatial Trends

17-mile long

estuary

RM 0 RM 17

Tidal Estuary Example

Inflow

Tidal Currents

Dam

Major Tidal

Exchange


L

B

G

Use of Beryllium-7 to Identify Current Spatial Trends

Four studies of 2,3,7,8-TCDD and 4,4-DDE.


1995 0-6 inch sample





L

B

G

2,3,7,8-TCDD vs. Distance along Estuary

0.1

1

10

100

1000

10000

100000

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

2,3

,7,8

-TC

DD

Co

ncen

trati

on

(n

g/k

g)

River Mile

To the Sea


L

B

G

4,4’-DDE vs. Distance along Estuary

0.1

1

10

100

1000

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0

4,4

'-D

DE

Co

ncen

trati

on

(u

g/k

g)

River Mile

To the Sea


L

B

G

Approximately 200-mile long river

Hudson River Example

Inflow Tidal

Exchange

4l

Cesium-137 Core Dating

Tidal Currents One directional

freshwater flow

Inflow


L

B

G

24

Circa 1970 Peak Identified all the way to RM 0

Similar Recovery Rates Post 1980


L

B

G


17-mile long

estuary

RM 0 RM 17


Inflow

Tidal Currents

Dam

Major Tidal

Exchange


L

B

G

Cs-137 Profiles Permit Comparisons

across the Entire Length of the Estuary

26

Depth to Cs-137 Maximum

3 ft 7 ft 13 ft 2 ft 4 ft


L

B

G

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

0.001 0.01 0.1 1 10

Ap

pro

xim

ate

Ye

ar o

f D

ep

ositio

n

2,3,7,8 - TCDD (ug/kg)

Historical Dioxin Levels were Extremely High

Non-contiguous

core segment

1975

1980

1985

1990

1995

2000

2005

0.1 1 10

Ap

pro

xim

ate

Ye

ar o

f D

ep

ositio

n

2,3,7,8 - TCDD (ug/kg)

RM 1.4

RM 2.2

RM 7.8

RM 11

RM 12.6

2007

27

1975

1980

1985

1990

1995

2000

2005

0.1 1 10

Ap

pro

xim

ate

Ye

ar o

f D

ep

ositio

n

2,3,7,8 - TCDD (ug/kg)

RM 1.4

RM 2.2

RM 7.8

RM 11

RM 12.6

. . . but Recent Levels are Declining Slowly at Best


L

B

G

Dated Sediment Cores Permit Forensic Analysis

of Historical Deposition and Sources

1935

1945

1955

1965

1975

1985

1995

2005

0.00 0.20 0.40 0.60 0.80 1.00 1.20

Ratio 2,3,7,8 - TCDD to Total TCDD

Depth

(R

epre

sente

d b

y Y

ear)

RM 1.4

RM 2.2

RM 7.8

RM 11

RM 12.6

Ap

pro

xim

ate

Year

of

Dep

osit

ion

Ratio

of ~0.7

28

Dioxin ratios have changed

only marginally over time.

Original source material is

largely unchanged.

But…Recent

release has

identifiably

different

signature..


L

B

G

Dep

th (

repre

sen

ted b

y ye

ars

)

Peak Total PCB

Load 1960s

Decline in Total PCB Load

1970s-Present

4i


Establishing The Current Rate of Recovery

Total PCB Concentration (ug/kg))

Rate of recovery is

equivalent to a 25

year half life.


L

B

G

Conclusions Sediments are a complex media in an energetic

environment.

Sufficient tracers are available to establish time of

deposition for the last 50 to 100 years, with a resolution of

10 years or less.

Establishing time of deposition permits comparisons across

large spatial scales and avoids natural “noise.”

Particle-bound contaminant histories are recorded in the

sediment and can be readily established.

Current conditions can be easily and inexpensively

established using the right tracers and sampling techniques.

The contaminant record provides a basis for forensic

analysis and can be used to establish the current rates of

recovery.

30

Documents

Edward A. Garvey, PhD, PG The Louis Berger Group, …s3.amazonaws.com/ebcne-web-content/fileadmin/pres/9-23-11/9-23-11... · The Louis Berger Group, Inc. L B G Edward A. Garvey, PhD,