Danny Reible – University of Texas
Heidi Blischke - GSI
1 Polydimethyl
siloxane
2Solid Phase Microextraction



Determine whether exceedances of performance standards from the
record of decision and/or comparison criteria of more recent water quality
criteria from EPA have occurred at any of the locations sampled. For this
objective to be successful, low level detection limits for carcinogenic PAHs
are necessary.
Assess concentration gradients between near surface and at depth. For
this objective to be successful, samples from discrete intervals within the
vertical sediment cap profile are required.
Define trends in interstitial water concentrations that may provide early
warning signs of potentially significant contaminant migration through a
cap (i.e. migration that may lead to exceedances of performance
standards in the near future). For this objective to be successful,
detection limits must be sufficiently low to detect PAHs to identify trends.
PAH< surface threshold
PAH<deep threshold
PAH< surface threshold
PAH> deep threshold


No Evidence of
Cap
breakthrough
Currently Compliant
with AWQS
AWQS noncompliant.
PAH> surface threshold
 No Evidence of BottomPAH<deep threshold
Up breakthrough
PAH>thresholds

AWQS noncompliant.
Evidence of Bottom-Up
breakthrough
C f  K fwC pw

Average
deviation
<5%
Average
deviation
~12%
6.0
5.5
Log Kfw
5.0
Log Kfw

0.839*LogKow+0.117
Linear (Log Kfw)
4.5
4.0
y = 0.757x + 0.513
R² = 0.970
3.5
3.0
3.0
3.5
4.0
4.5
5.0
Log Kow
5.5
6.0
6.5
7.0
Kfw
2
Concentration
r
Linearity
78.5
4027
2591
4227
3662
10938
10810
30327
35394
52898
85097
119712
120458
122795
142042
0.1547
0.985
0.9817
0.9984
0.9996
0.9973
0.998
0.9985
0.9987
0.9967
0.9978
0.9945
0.9781
0.9755
0.9241
COV PDMS
88.8%
10.0%
70.2%
5.6%
14.1%
1.3%
18.1%
9.9%
8.1%
19.1%
3.9%
11.6%
8.0%
5.8%
5.5%
161013
0.9179
7.0%
Magnification
Naphthalene
DBF
2-MNP
Fluorene
Acenaphthene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Chrysene
Benz[a]anth
Benzo[b]fluoranthene
Benzo[k]fluoranthene
Benzo[a]pyrene
Dibenz[a,h]anthracene
Benzo[ghi]perylene +
Indenopyrene
Average w/o Naphthalenes
Conventional Detection Limit
COV Conventional Analysis
* 3cm of 10 um layer on 210 um core
**1 cm of 30 um layer on 1000um core
PDMS MDL
µg/L
*
PDMS MDL
µg/L
**
0.3332
0.0123
0.0268
0.0697
0.0315
0.0076
0.0075
0.0025
0.0021
0.00048
0.00011
0.00011
0.00002
0.00005
0.00007
0.07207
0.00265
0.00580
0.01508
0.00680
0.00164
0.00161
0.00054
0.00046
0.00010
0.00002
0.00002
0.00000
0.00001
0.00001
0.00010
0.00002
0.98279 9.1%+/-5%
0.0118
10%+/-8%

Pros:



Cons:


Detection Limits in smaller fiber (not used at M&B)
Lower detection limits
for CPAHs – well below
NRWQC
Early warning of
increasing
concentrations
Naphthalenes have
higher detection limits
Detection limit
function of
hydrophobicity

24 SPME passive samplers were installed:
 2 surface water (background) locations
 22 sediment cap monitoring locations

After 7 days of exposure, 23 samplers were retrieved:
 One sampler was lost (Location 4)

Target sample depths:



6” below the top of the armoring layer
6” into the sand cap
12” into the sand cap
The actual sample depths varied slightly from the target

Pre deployment
 Fiber and sampler cleaning (solvent rinse)
 Fiber placement in sampler

Deployment
 Via divers except at shore
 Difficulty in achieving target depths in armored area

Retrieval after 1 week
 Sectioned on site and placed into pre-filled autosampling vial
 Shipped back to UT and analyzed directly

Static Lab Expts
PAH Kinetics in Bare Fiber
 Anacostia River
600
Phe
500
Slow Equilibrium?
 Low cap sorption
capacity

Speed Equilibrium?
 Tides
 Groundwater flow
400
Fiber conc (g/L)

Chrysene
300
200
B[b]F
100
B[a]P
0
0
5
10
Time (d)
15
20

Estimation
 Performance Reference
Compounds
 Time Series
 Two different size fibers

Puget Sound data
shown
 7 days
 Tidal system but no
shoreline
 Nonsorbing cap

PDMS
 Fiber-water partition coefficient (error ~ 10%))
 Equilibrium
 PRC or two size fibers (failed in first application to site)
 Experience suggests near equilibrium for low MW PAH but high MW
PAH may be underestimated
 Maximum underestimation ~factor of 2-3
 Site specific kinetic evaluation is recommended or use of thin fibers

Conventional pore water sampling (Henry’s probe)




Poor detection limits (often near criteria)
Poor depth control
Potential for solids resuspension and sampling artifacts
Includes both dissolved and colloidally/particulate bound
contaminants
PAH Tissue Correlation Concentration
(Centrifugation)
OC Normalized Sediment Concentration
35
30
25
20
R² = 0.2703
15
10
5
0
0.0
5000.0
10000.0 15000.0 20000.0 25000.0 30000.0
Sediment Concentration (ug/kg OC)
Tissue Concentration (ug/kg)
Tissue Concentration (ug/kg)
35
30
25
15
10
5
0
0.0
100.0
200.0
300.0
400.0
500.0
600.0
Pore Water Concentration (ng/L)
Pore Water Concentration (2 day SPME)
Pore Water Concentration (21 day SPME)
35
35
30
R² = 0.7583
25
20
15
10
5
0
0.0
0.5
1.0
1.5
Pore Water Concentration (ng/L)
2.0
Tissue Concentration (ug/kg)
Tissue Concentration (ug/kg)
R² = 0.4422
20
R² = 0.8723
30
25
20
15
10
5
0
0.0
1.0
2.0
3.0
Pore Water Concentration (ng/L)
4.0



35% of possible compound detects measured
LPAHs were detected more frequently than other PAHs
Acenapthene and phenanthrene were detected in all
samples
 Only LPAHs were detected in the two background samples

The three most hydrophobic compounds were not
detected in any samples (likely due to low mobility)
 Dibenz(a,h)anthracene
 Benzo(g,h,i)perylene
 Indeno(1,2,3-cd)pyrene



Near shore vertical
concentration profiles
are fairly uniform.
Concentrations either
stay the same or
increase slightly with
depth.
Possibly due to mixing
caused by tidal
fluctuations.


Off shore vertical
concentration
profiles display
greater gradients
than near shore
profiles.
Concentrations
increase with
depth.

Individual PAH concentrations were compared for Locations
5, 9, 12, and 16.



All concentrations increased at Location 5.
Locations 9 and 16 showed some concentrations increasing and some
decreasing
Most concentrations decreased at Location 12.
100
10
y = 416.93x1.2574
R² = 0.9271
10
1
0.1
SPME 2010
SPME 2010
1
100
0.01
0.001
0.01
0.001
0.0001
0.0001
0.00001
1E-05
0.000001
0.000001 0.00001 0.0001
0.001
0.01
SPME 2009 (Location 5)
0.1
1
10
y = 0.01x0.5575
R² = 0.8391
0.1
1E-06
0.000001 0.00001 0.0001
0.001
0.01
SPME 2009 (Location 12)
0.1
1
10
Normalized pore water concn
10
1
NRWQC
Naphthalene
0.1
Fluorene
0.01
Anthracene
Fluoranthene
0.001
pyrene
chrysene
0.0001
B[a]A
0.00001
B[b]F
B[k]F
0.000001
B[a]P
0.0000001
1E-08
0
5
10
15
sample locations
20
25

Only one exceedance: chrysene at location 5
 about 12 inches into the sand portion of the cap
 18-24 inches below sediment water interface.
 0.035 µg/L (duplicate 0.005 µg/L)

Two other detections approached NRWQC at the
deepest sample intervals:
 Benz(a)anthracene was 80% of the criterion at Location 5
 Benz(a)anthracene was 60% of the criterion at Location 16

All other compound concentrations at all other
locations and depths were well below the NRWQC.
Comparison of Duplicates- All samples
1.00E+04
IA data
y=x
R² = 1
1.00E+03
B samples PAH concentrations (ug/L)
1.00E+02
All Data Fit
y = 0.9353x0.9821
R² = 0.9691
1.00E+01
1.00E+00
1.00E-01
6" Subarmoring
12" Subarmoring
Interarmoring
y = 0.9795x0.9852
R² = 0.9742
6" Subarmoring
y = 1.0331x0.9903
R² = 0.9739
1.00E-02
1.00E-03
12" Subarmoring
y = 0.8512x0.9767
R² = 0.9611
1.00E-04
1.00E-05
1.00E-06
1.00E-06
1.00E-05
1.00E-04
1.00E-03
1.00E-02
1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04
A samples PAH Concentrations (ug/L)
Site 5 ~100 times higher than adjacent site (local contamination)
100
Site 5 ug/L
10
1
-6 cm
0.1
-7 cm
0.01
-18 cm
parity
0.001
0.0001
0.0001
0.001
0.01
Site 17 ug/L
0.1
1

35% of possible compound detections
 compared to less than 10% in conventional approaches
 50%+ in preceding years suggesting general downward trend




LPAHs detected more frequently than LPAHs
No comparison criteria exceeded in inter-armoring or 6 inches
into sand cap
One cPAH (chrysene) exceeded at 12 inches into sand cap at
Location 5
Few increases noted at 12 inches into sand cap in 2010 samples
relative to 2009 – will get trend data in 5-year sampling events for
early warning
Sediment cap is protective of surface water and functioning as
designed

SPME
 Detection limits << criteria
 More detections from which to draw conclusions
 Higher spatial resolution (no dilution by withdrawing
excessing water volume)
 Eliminates particulate and colloidal artifacts
 Minimal sample processing
 1 day placement, 1 day retrieval vs 1 week conventional
sampling requirement
 More biologically relevant indicator