EPA/600/R-10/062
February 2010
Bench-Scale Evaluation of Gas Ebullition
on the Release of Contaminants from Sediments
Final Report
EPA Contract Number: 68-C-00-185
Task Order #34
Mr. Terrence Lyons
Task Order Manager
Prepared by
Sandip Chattopadhyay
Vivek Lai
Eric Foote
Battelle
505 King Avenue
Columbus, Ohio 43201
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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Notice
The work reported in this document was funded by the United States Environmental
Protection Agency (U.S. EPA) under Task Order 34 of Contract 68-C-00-185 to Battelle.
In no event shall either the United States Government or Battelle have any responsibility
or liability for any consequences of any use, misuse, inability to use, or reliance on the
information contained herein, nor does either warrant or otherwise represent in any way
the accuracy, adequacy, efficacy, or applicability of the contents hereof. The content of
the information does not necessarily reflect the position or the policy of either the United
States Government or Battelle, and no official endorsement should be inferred.
Ill
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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting
the Nation's land, air, and water resources. Under a mandate of national environmental laws,
the Agency strives to formulate and implement actions leading to a compatible balance
between human activities and the ability of natural systems to support and nurture life. To
meet this mandate, EPA's research program is providing data and technical support for
solving environmental problems today and building a science knowledge base necessary to
manage our ecological resources wisely, understand how pollutants affect our health, and
prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory (NRMRL) is the agency's center for
investigation of technological and management approaches for preventing and reducing risks
from pollution that threaten human health and the environment. The focus of the laboratory's
research program is on methods and their cost-effectiveness for prevention and control of
pollution to air, land, water, and subsurface resources; protection of water quality in public
water systems; remediation of contaminated sites, sediments and ground water; prevention
and control of indoor air pollution; and restoration of ecosystems. NRMRL collaborates with
both public and private sector partners to foster technologies that reduce the cost of
compliance and to anticipate emerging problems. NRMRL's research provides solutions to
environmental problems by: developing and promoting technologies that protect and improve
the environment; advancing scientific and engineering information to support regulatory and
policy decisions; and providing the technical support and information transfer to ensure
implementation of environmental regulations and strategies at the national, state, and
community levels.
This publication has been produced as part of the laboratory's strategic long-term research
plan. It is published and made available by EPA's Office of Research and Development to
assist the user community and to link researchers with their clients.
Sally Gutierrez, Director
National Risk Management Research Laboratory
IV
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CONTENTS
CONTENTS iii
FIGURES iv
TABLES iv
ABBREVIATIONS AND ACRONYMS vi
EXECUTIVE SUMMARY vii
Section 1.0 PROJECT BACKGROUND AND OBJECTIVES 1
1.1 Problem Definition 1
1.2 Project Objective 5
1.3 Report Organization 6
Section 2.0 MATERIALS AND METHODS 7
2.1 Collection of Sediment and Water Samples 7
2.1.1 Lake Hartwell Sediment Collection 7
2.1.2 Eagle Harbor Sediment Collection 7
2.1.3 Water Sample Collection 7
2.2 Sediment Processing for Experiments 7
2.3. Preparation of Serum Bottles for Microcosm Study 8
2.4 Measurement of Gas Generation from Microcosm Bottles 12
2.5 Column Study 13
2.5.1 Construction of Gas Ebullition Columns 21
2.5.2 Packing of Columns 21
2.5.3 Variation of Gas Flow through the Columns 24
2.5.4 Analyses of Column Materials 25
2.5.5 Measurements of pH, ORP, DO and Turbidity 25
2.6 Analytical Techniques: PCBs and PAH 25
2.6.1 Sediment Sample Processing 25
2.6.2 PUF Sample Processing 26
2.6.3 Large Volume (>1 L) Water Sample Processing 26
2.6.4 Small Volume (<0.5 L) Water Sample Processing 26
2.6.5 Instrumental Analysis 26
2.7 Analytical Techniques: Gas Analysis 27
Section 3.0 RESULTS AND DISCUSSION 28
3.1 Microcosm Study 29
3.1.1 Sediment and Water Analysis of Microcosm Bottles 29
3.1.2 pH and Redox Potential of Microcosm Bottles 29
3.2 Column Study 39
3.2.1 Eagle Harbor Columns 39
3.2.1.1 pH, Redox Potential, Dissolved Oxygen and Turbidity 40
3.2.1.2 PUF Analysis 40
3.2.1.3 PAH Concentration Profile in Eagle Harbor Sediment and Water 41
3.2.1.4 Mass Balance of tPAH 42
3.2.1.5 PAH in Cap Material 43
3.2.2 Lake Hartwell Columns 43
3.2.2.1 pH, Redox Potential, Dissolved Oxygen and Turbidity 43
3.2.2.2 PUF Analysis 43
3.2.2.3 Mass Balance of tP AH 44
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Section 4.0 SUMMARY 57
Section 5.0 REFERENCES 60
FIGURES
Figure 1-1. Eagle Harbor Site Map 2
Figure 1-2 Lake Hartwell, South Carolina 3
Figure 2-1. Eagle Harbor Site Map 9
Figure 2-2. Lake Hartwell Site Transect Locations 10
Figure 2-3. Microcosm Bottles: Lake Hartwell (left) and Eagle Harbor (right) 11
Figure 2-4. Larger Bottles with a Glass Stem 13
Figure 2-5. Measurement of Gas Bubbles from the Serum Bottles 14
Figure 2-6. Schematic Diagram of Eagle Harbor Columns 22
Figure 2-7. Photograph of Eagle Harbor Columns 23
Figure 2-8. Photograph of Lake Hartwell Columns 23
Figure 2-9. Eagle Harbor Water, Cap and Sediment (after 19-weeks) 25
Figure 2-10. Removal of Column Water for pH, ORP, DO and Turbidity Measurements 26
Figure 3-1. Eagle Harbor Gas Generation at 10°C, 25°C, 37°C 30
Figure 3-2. Lake Hartwell Gas Generation at 10°C, 25°C, 37°C 31
Figure 3-3. Eagle Harbor Microcosm Bottles Sediment [upper] and Water [lower] Concentrations at
10 C, 25°C and 37 °C 36
Figure 3-4. Lake Hartwell Microcosm Sediment (upper) and Water (lower) after 90-days of Incubation
at 10 °C, Room Temperature and 37 °C 37
Figure 3-5. Relationship between the Redox Potential and Idealized Terminal 38
Figure 3-6. PAHs Recovered from the Eagle Harbor Sediment (with and without cap) after Low Flow
Gas Sparging for 6-weeks and 19 weeks 46
Figure 3-7. PAHs Recovered from the Eagle Harbor Sediment (with and without cap) after High
Flow Gas Sparging for 6-weeks and 19-weeks 47
Figure 3 -8. PAH profiles of Eagle Harbor initial, uncapped and capped sediment (low flow) 48
Figure 3 -9. PAH profiles of Eagle Harbor initial, uncapped and capped water (high flow) 49
Figure 3-10 The amount in (ng) of tPAH in the initial sediment and water and the sediment, water, cap
and PUF after 19-weeks for Low Flow Columns (6.5 ml/min) 50
Figure 3-11. The amount in (ng) of PAH in the initial sediment and water and the sediment, water, cap
and PUF after 19-weeks for High Flow Columns (18.7 ml/min) 51
Figure 3-12. Eagle Harbor cap material at low flow 6.5 ml/min (upper graph) and high flow 52
Figure 3-13. Comparison of PCBs at low flow (6.5 ml/min) for spiked and unspiked Lake Hartwell
sediment 53
Figure 3-14. Comparison of PCBs at low flow (6.5 ml/min) and high flow (18.7 ml/min) for unspiked
Lake Hartwell sediment 54
Figure 3-15. Lake Hartwell tPCB comparison initially and after 19-weeks for unspiked sediment at low
flow (6.5 ml/min) and high flow (18.7 ml/min) 55
Figure 3-16. tPCB comparison initially and after 19-weeks for spiked and unspiked sediment at low
flow (6.5 ml/min) 56
VI
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TABLES
Table 2-1. Supplies and Accessories Used to Prepare the Microcosm Bottles 8
Table 2-2. Eagle Harbor Serum Bottle Test Parameters 15
Table 2-3. Lake Hartwell Serum Bottle Test Parameters 18
Table 2-4. Column Parameters of Eagle Harbor and Lake Hartwell Setup 24
Table 2-5. Correction Factors for the Gas Mixture and Pressure 24
Table 3-1. Gas Generation and Headspace Analysis of Microcosm Bottles Containing Eagle Harbor
Sediment 32
Table 3-2. Gas Generation and Headspace Analysis of Microcosm Bottles Containing Lake Hartwell
Harbor Sediment 34
Table 3-3. pH and ORP of Lake Hartwell and Eagle Harbor Microcosm Bottles after 120-Days 39
Table 3-4. Eagle Harbor pH, ORP, DO and Turbidity of Column Water at the 41
Table 3-5. Lake Hartwell Equilibrium Water pH, ORP, DO and Turbidity Measurements After 19-weeks
Gas Sparging Operations 43
APPENDICES
Appendix A: Individual Test Result Tables
Appendix B: Lake Hartwell and Eagle Harbor Column Study Data
Appendix C: Battelle Duxbury Data and QA
Appendix D: Analytical Results for 14 and 90 Days
vn
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CO2
COC
DO
EPC
GC/MS
HOPE
HP
IS
MSB
NAPL
ORP
PAH
PCB
PFTBA
psi
PUF
QA
RIs
rpm
SIM
SIS
tPAH
U.S. EPA
VOA
ABBREVIATIONS AND ACRONYMS
methane
carbon dioxide
contaminant of concern
dissolved oxygen
electronic pressure controlled
gas chromatography/mass spectrometry
high density polyethylene
Hewlett Packard
internal standard
mass selective detector
non-aqueous phase liquid
oxidation-reduction potential
polycyclic aromatic hydrocarbon
polychlorinated biphenyl
perfluorotributylamine
pounds per square inch
polyurethane foam
quality assurance
retention indices
rotations per minute
selected ion monitoring
surrogate internal standards
total polycyclic aromatic hydrocarbon
United States Environmental Protection Agency
volatile organic analysis
Vlll
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EXECUTIVE SUMMARY
When sediments are rich in organic, anaerobic and aerobic processes, they generate biogenic
gases, mainly methane (CH^ and carbon dioxide (CO2). A higher CH4 content in the gas is indicative of
methanogenic conditions and a reductive environment. This condition facilitates the transfer of
contaminants of concern (COCs) from the sediment through the surrounding water to the atmosphere.
Prior research at Eagle Harbor (Bainbridge Island, Washington) demonstrated that when poly cyclic
aromatic hydrocarbon (PAH) contaminated sediment was capped, biogenic gas began to percolate
through the cap matrix. Prior research on polychlorinated biphenyl (PCB)-contaminated sediment at Lake
Hartwell (Clemson, South Carolina) demonstrated that as the organic concentration in Lake Hartwell
increased, the generation of gas increased. The volume of gas generated was dependent on many factors
including the amount of sediment, seasonal conditions, depth of the lake, and water temperature.
The release of gas bubbles from sediments into overlying water (ebullition) is a major
mechanism for the discharge of biogenic and geogenic gases into the water body. Microbial breakdown
of sedimentary organic matter produces gas bubbles which are inherently hydrophobic and tend to
accumulate both hydrophobic organic contaminants and colloids from porewater. Through this
mechanism the ebullition of CH^ and CO2 in contaminated sediments may contribute to the release of
CoCs from the sediment-water interface and into the water column. With the formation of gas bubbles in
the sediment, a three phase benthic system exists: solid sediment particles, water and gas. Organic
compounds present in sediment will partition between the solid sediment particles and liquid porewater
based on the sorptive characteristics of the sediment and physicochemical properties of the COCs.
Partitioning of the organic contaminant between the gas and water phase is determined by the gas-water
partition coefficient of individual components of the COC. The transport of contaminants would
therefore occur when gas bubbles, containing volatilized organic compounds, are ejected from the
sediment and transported directly to the atmosphere. Transfer of organic contaminants from the gas
bubbles to the overlying water may occur during transit through the water column as a result of gas to
water partitioning. Microbial breakdown of sedimentary organic matter produces gases, which tend to
migrate out of sediments into overlying water and are eventually vented to the atmosphere. Gas
generation indicates that microorganisms are able to break down sedimentary organic matter for energy
and nutrients. The duration of gas production is still unknown, since gas production is still occurring. No
systematic column studies have explored the phenomenon of gas ebullition in sediments on the stability
and effectiveness of the cap and consequently to the release of sediment/cap bound contaminants to
overlying water.
This report describes the performance of microcosm and a bench-scale column studies to
attempt to understand and quantify the release of COCs from uncapped and capped sediments. The gas
ebullition through the sediment bed was simulated by sparging mixed anaerobic gas at two flow rates (6.5
and 18.5 mL/min).
The microcosm experiments indicated that the serum bottles tested maintained anaerobic
conditions. Higher percentages of CH4 and CO2 were contained in the headspace of the Lake Hartwell
serum bottles than the Eagle Harbor samples at 37 °C. No detectable level of gas was measured at the
lower temperatures (10 °C and 25 °C) for either the Eagle Harbor or Lake Hartwell sediments. Higher
concentrations of PAHs (ng/g) were observed in the Eagle Harbor sediment as the temperature increased
from 10 °C to 37 °C. The concentrations of PCBs (ng/g) in the serum bottles containing Lake Hartwell
sediment with an incubation temperature of 10 °C were higher than those incubated at 25 °C and 37 °C.
However, the PCB concentrations (ng/L) in water increased as the incubation temperature increased from
10 °C to 37 °C. The PCBs in the Lake Hartwell sediment partitioned into the water phase more strongly
at higher temperatures than lower temperatures.
ix
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The results of the simulated gas ebullition column experiments showed that the total poly cyclic
aromatic hydrocarbon (tPAH) captured by the polyurethane foam (PUF) during the 6th and 19th week
sampling events from the uncapped Eagle Harbor columns at low gas flow rate (6.5 mL/min) conditions
was more than the capped columns. The uncapped PUFs also recovered PAHs with higher molecular
weights, which were not detected in the capped PUF. At high gas flow rates (18.7 mL/min), the PUFs
captured more tPAH from the uncapped sediment columns than the capped columns. After 19-weeks of
gas sparging, the PUFs for the capped column sorbed lower molecular weight PAH compounds, such as
1-methylnaphthalene and Cl-naphthalenes, than the uncapped column. However, the PUFs from the
uncapped columns consistently sorbed higher molecular weight PAH compounds than the capped
column.
The PUFs at the outlet of columns containing Lake Hartwell spiked and unspiked sediment
captured 1041 and 164 ng of tPCB, respectively, at low gas flow conditions. The PUFs also captured
higher molecular weight PCBs (such as C15(l 10)) from the PCB spiked sediment.
During high gas sparging, the PUFs sorbed more PCBs from columns that were packed with
unspiked Lake Hartwell sediment in comparison to the low flow columns. The transfer of PCBs from the
sediment to the water column and thereafter to the air appeared to be more dependent on the sparging
flow rate than the concentration of PCB in the sediment. Higher concentrations of PCBs (hydrophobic)
could be sorbed in the sediment with a low risk of escape as long as the gas ebullition rate was low.
Higher gas sparging also resulted in the release of higher molecular weight PCBs.
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Section 1.0 PROJECT BACKGROUND AND OBJECTIVES
The release of gas bubbles from sediments into overlying water (ebullition) is a major
mechanism for the discharge of biogenic and geogenic gases into the water body. Microbial breakdown
of sedimentary organic matter produces gas bubbles which are inherently hydrophobic and tend to
accumulate both hydrophobic organic contaminants and colloids from porewater. Through this
mechanism the ebullition of methane (CFL,) and carbon dioxide (CO2) in contaminated sediments, may
contribute to the release of contaminants of concern (COCs) from the sediment-water interface and into
the water column.
Previous research conducted by U.S. EPA for polycyclic aromatic hydrocarbon (PAH)
contaminated sediments at Eagle Harbor (Bainbridge Island, Washington; Figure 1-2) also demonstrated
the potential for dissolved gases to percolate through the in-place sediment cap material (sand) by
convective or diffusive transport. It was hypothesized that biogenic gas transport may facilitate the
migration of PAHs through the cap by providing avenues for release or solubilizing the COCs carrying
them through the porous media dissolved in the gaseous molecules. The U.S. EPA has also quantified the
volume of gas produced at various depths within the cap material and underlying sediments and found
that gas production at this site was extremely low and that there was insufficient gas volume for PAHs
analysis.
Previous research conducted by the United States Environmental Protection Agency (U.S.
EPA) for polychlorinated biphenyl (PCB) contaminated sediments at Lake Hartwell, in Clemson, South
Carolina (Figure 1-1), showed that high organic loading in sediments resulted in significant gas ebullition
at the site. Studies were conducted over the course of one year and sediment gas production was
quantified through the use of submerged gas collection chambers. Gas production rates were calculated
and were shown to be highly dependant upon the lake depth, organic material and water temperature.
Although the gas production in collection chambers was significant in certain test locations at Lake
Hartwell, the volume of gas produced during these monitoring events was not sufficient to measure PCB
content.
1.1 Problem Definition
The atmospheric concentration of CIL, (a greenhouse gas) has risen ~1% per year (Ostrovsky,
2003); it is an important product of the anaerobic degradation of organic material in bottom sediment.
Gas ebullition from the bottom sediments of natural water could substantially envelop the total methane
flux. Ostrovsky (2003) reported the mean rising velocity of bubbles as 0.22 ±0.1 cm/s by clean bubbles
of-0.6 mm radius or dirty bubbles with a radius of up to a few millimeters. Estimating gas emissions
from lakes and reservoirs is difficult since there are at least four emission pathways which may be
regulated differently:
• Ebullition flux,
• Diffusive flux,
• Storage flux, and
• Flux through the aquatic vegetation.
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Lynnwood
Kenmore
Bellevue
SCALE IN M _CS
SOURCE: WCDIFIED FROM L.5. EPA, 1995
Figure 1-1. Eagle Harbor Site Map
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Figure 1-2. Lake Hartwell, South Carolina
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Bastviken et al. (2004) reported that the majority of Clr^ production occurs in anoxic sediment.
As a result of the diffusive export from anoxic sediment, CHt eventually enters the water column. As
soon as QrU reaches an anoxic environment or water, a large proportion is likely oxidized by ClrLr
oxidizing bacteria. Most of the CH4 that reaches the upper mixed layer of the water column will be
emitted by the diffusive flux. This flux component depends on the difference in CHt concentration
between the water and the atmosphere, and on the physical rate of exchange between air and water,
usually expressed as a piston velocity (turbulence, wind velocity) (Stumm and Morgan, 1996).
Though there is a substantial diurnal variation in CH4 emissions (9 to 158% greater emission
during the day), the average and median of gas emissions reported by Bastviken et al. (2004) were 69%
and 53%, respectively. These authors reported that the average surface water CH4 concentrations in 13
Swedish lakes were 0.08 - 1.89 (imole/L. Fendinger et al. (1992) reported that biogenic production of
sediment gas bubbles typically contains 46 to 95% CFLt, 3 to 50% nitrogen, and trace quantities of CO2
and hydrogen. The rate of bubble production from bottom sediment is a function of the composition,
redox potential, microbial population, water depth and trophic status of the water body.
Organic compounds present in sediment will partition between the solid sediment particles and
liquid porewater based on the sorptive characteristics of the sediment and physicochemical properties of
the COCs. Microbial breakdown of sedimentary organic matter produces gases, which tend to migrate
out of sediments into overlying water and are eventually vented to the atmosphere. With gas bubble
formation in the sediment, a three phase benthic system exists: solid sediment particles, water and gas.
The preferential pathway generated by gas migration may provide a means for the migration of separate
phase material as well as contaminants to the sediment-water interface. Gas bubbles are inherently
hydrophobic and tend to accumulate both hydrophobic organic contaminants and colloids from porewater,
therefore their migration can have a significant effect on the transport of contaminants through the water
column. The transport of contaminants would therefore occur when gas bubbles, containing volatilized
organic compounds, are ejected from the sediment and transported directly to the atmosphere. The
transfer of organic contaminants from the gas bubbles to the overlying water may occur during transit
through the water column as a result of gas to water partitioning. Partitioning of the organic contaminant
between the gas and water phase is determined by the gas-water partition coefficient of individual
components of the COCs. Buoyancy driven migration of the gas opens channels through a cap, or if
contained by an impermeable layer, may accumulate and potentially cause greater damage when
ultimately released. The effective sediment-water exchange coefficients of PCBs (Thibodeaux et al.,
2001) suggest that the heavier, more strongly partitioning congeners are moved more rapidly by particle-
based processes (e.g., particle mixing by bioturbation) as they exhibit higher adsorption coefficients,
whereas lighter congeners diffuse faster through porewater and benthic boundary layers.
Hughes et al. (2004) reported that gas generated by organic degradation processes in sediment
has the ability to destabilize non-aqueous phase liquids (NAPLs). Microcosm experiments using
Anacostia River sediment were conducted. Headspace analysis of the microcosms revealed the vast
majority of the gas produced was CFLt, which is typical for anoxic sediments. The increase in gas
generation with temperature is expected for methanogenic bacteria, since these organisms have an
average optimal growth temperature of 37 °C. An initial gas consumption phase was observed in the
microcosms, during which time residual O2 in the water added to the system was consumed. This was
followed by an acclimation period, which lasted at least five days at 35 °C, since gas production was not
observed until after this time. Hughes et al. (2004) indicated that these two phases explain the relatively
large standard deviation for gas production rates. Gas production continued for over 80 days, with the
rates remaining constant. A sediment sample that was initially incubated at 4 °C for 60 days began
generating gas when it was transferred to 35 °C, suggesting that the microbial population was dormant at
4 °C. Given the mass of sediment loaded into the bottles and its wet bulk density, the authors estimated
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that the gas production at 22 °C from a sediment bed the size of a football field (300 ft x 150 ft x 1 ft) is
estimated to be ~11,475 L of gas per day (11.5 nvVday). Normalizing this value based on sediment-water
interfacial area (41,827 m2) yields agas production rate of 2.74 L/m2 day. This estimate is viewed as a
slight overestimate of the actual ebullitive flux in the Anacostia River for two reasons:
• The natural bubble ebullition in tidal systems occurs in pulses, due to changes in
hydrostatic water pressure accompanied with tidal flow. Ebullitive flux is "turned on"
during low tide when overlying hydrostatic pressure is decreased, and then abruptly stops
when high tide begins.
• The experimental design for obtaining the gas generation rate measures overpressure in
the serum bottle, meaning that both trapped gas and bubbled gas is measured. This is not
representative of field techniques, however, which typically measure only ebullitive flux
from the sediment.
Gas generation indicates that microorganisms are able to break down sedimentary organic
matter for energy and nutrients. The duration of gas production is still unknown. There have been no
systematic column studies exploring the phenomenon of gas ebullition in sediments on the stability and
effectiveness of the cap and consequently to the release of sediment/cap bound contaminants to overlying
water.
1.2 Project Objective
The principal objective of this project is to better understand the effect of gas ebullition on the
movement and release of PAHs for Eagle Harbor sediments and PCBs for Lake Hartwell sediments in
controlled laboratory experiments. Sediment samples collected from two locations at each of these two
sites were used to conduct batch and column experiments in the laboratory. The use of sediments from
two locations provided the contaminant variability needed to conduct the experiments. Apart from geo-
logical differences, Eagle Harbor sediment was capped and Lake Hartwell was not capped. In regard to
groundwater seeps, capping provides a means to control oxygen conditions within the groundwater plume
and potentially provide the residence time to achieve degradation of compounds. The results obtained
from these two site-specific sediments were evaluated.
The study was performed in two phases. Phase 1 involved bench-scale microcosm tests to
measure and understand the volume of gas produced by each type of sediment at three test temperatures.
Phase 2, which was conducted simultaneously, involved column tests to investigate the partitioning and
mass transfer of COCs in sediment-water systems.
This laboratory study was conducted to address the following questions:
(1) Does the gas ebullition cause the release of PAHs and PCBs from the selected
sediment-water systems?
(2) If the abovementioned COCs are releasing, can the COCs be quantified?
(3) Is the released concentration of contaminant dependent upon temperature of the
sediment-water system?
(4) Is the released concentration of contaminant dependent upon the flow rate of gas
bubbles passing through the water column?
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1.3 Report Organization
The materials and experimental methods used for the microcosm and column tests are
described in Section 2.0. Section 3.0 contains the results and discussion; and Section 4.0 presents a
summary of the results from this study. The appendices present additional information regarding test
results. Tables and Figures containing the individual test results are included in Appendices A and B.
The analytical results including quality assurance (QA) narratives are included in Appendices C and D.
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Section 2.0 MATERIALS AND METHODS
This section describes the details of the preparation of serum bottles and their incubation for the
microcosm study. The setup and operation of columns to simulate the gas ebullition are also discussed.
Various physical and analytical measurements conducted for the microcosm and column experiments are
presented, including quantification of gas generated from the microcosm bottles, analysis of sediment and
water for PCBs, PAHs, and atmospheric analysis (CO2, O2 and CH/t) of gas samples.
2.1 Collection of Sediment and Water Samples
Sediment for microcosm and column experiments were collected from Eagle Harbor,
Washington, and Lake Hartwell, South Carolina using two discrete sampling methods discussed below.
2.1.1 Eagle Harbor Sediment Collection
Sediment samples were collected from Eagle Harbor at an approximate depth of six inches
below the sediment surface (Figure 2-2). The sediments were collected using shovels in an uncapped area
of the harbor on the east side of the peninsula during low tide. A total of two 5-gallon buckets were filled
with these sediments and shipped to Battelle's laboratories for processing and analysis.
2.1.2 Lake Hartwell Sediment Collection
A box core sampler was used to collect sediments from Lake Hartwell. The core device was
approximately 6 inches by 6 inches wide and 2 feet long. The box core barrel was hand driven from a
work platform on the water and pushed to a depth of approximately 20 inches. Afterwards, the box core
was retrieved and brought to the surface; the core location (georeference), time of collection and depth of
recovery were recorded. In this manner, a total of two cores were collected from Transect O (Figure 2-1)
and an additional two cores were collected from Transect P of the Twelve-Mile Creek arm of Lake
Hartwell. Each of the cores was composited into 1.5 gallon bucket and prepared for shipment to the
Battelle laboratory for processing and analysis.
2.1.3 Water Sample Collection
Water for microcosm and column experiments was also collected from Eagle Harbor and Lake
Hartwell. At Eagle Harbor, water was collected directly into two 5 gallon buckets at the shoreline.
At Lake Hartwell, water was collected from a work platform on the water surface using a Van
Dorn sampler. The sampler was lowered to approximately mid-depth in the water column (approximately
7 feet) and then brought up to the surface where it was composited from Transect O and P into two 5
gallon buckets.
All buckets were sealed and shipped to Battelle's laboratories, where they were stored at a
controlled temperature (4±2°C). Before conducting the bench-scale experiments, both sediment and
water samples were brought to room temperature.
2.2 Sediment Processing for Experiments
Prior to the bench-scale studies, a representative sample of sediment was collected from the
center of each bucket and placed immediately into a glove-box containing an anaerobic atmosphere
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consisting of nitrogen gas. Any twigs, shells, leaves or small stones were removed from the sediment
samples. Compositing and homogenization were performed inside the glove box using a small
mechanical mixer equipped with a stainless steel impeller. Mixing was performed as quickly and
efficiently as possible to minimize drying and any impact to particle size. Visual observations, including
sediment color, consistency, and odor, were recorded. After homogenization, sediment samples were
transferred into serum bottles or glass columns as described in Section 2.3. During transfer, the sediments
were periodically mixed to minimize stratification effects due to differential settling.
2.3.
Preparation of Serum Bottles for Microcosm Study
Microcosm tests were conducted to determine the rate of gas generated from sediment and
water from Eagle Harbor and Lake Hartwell sediments and the site-specific water. The study was
conducted for 90-days with gas volume measurements taken after 1, 3, 7, 14, 21, 30, 45, 60 and 90 days.
The tests were conducted using duplicate samples and killed control bottles for each time point.
Prior to the preparation of the microcosm bottles, portions of Eagle Harbor and Lake Hartwell
sediments were transferred from sealed 5-gallon buckets to 1-L amber bottles. This transfer was
performed inside a glove box under a nitrogen (anaerobic) environment. The sediment from these 1-L
bottles were thereafter used to prepare the microcosm bottles.
The glass serum bottles, each having a capacity of 125-mL, were autoclaved three times for 20 minutes at
250 °F (121 °C) for sterilization. The serum bottles and other necessary supplies used to construct the
microcosms (Table 2-1) were transferred into the anaerobic chamber. An oxygen meter was used to
ensure that anaerobic chamber was oxygen free.
Table 2-1. Supplies and Accessories Used to Prepare the Microcosm Bottles
125-mL Microcosm
Bottles
20 mm Aluminum
Crimp Caps
20 mm Butyl
Stoppers
Crimper
Funnel
Bench top balance
Spatula
200-mL Graduated
Cylinder
Micropipet
Disposable glass pipet
Twenty-five grams of sediment was added into the narrow mouth of the serum bottles using a
clean, thin-stemmed spatula. The weight of the sediment was recorded using the bench top balance. A
funnel was inserted into the mouth of the bottle and a 200-mL graduated cylinder was filled to 125-mL
with site-specific water. The balance was tared and the water was slowly poured into the funnel. The
target volume was 120-mL for the Eagle Harbor bottles and 115-mL for the Lake Hartwell bottles,
respectively. Different volumes were used because the grain-size composition of the sediment varied.
The Eagle Harbor sediment was composed of fine to coarse granular elements and Lake Hartwell
sediment was clayey material. A glass volumetric pipet was used to transfer site water into the
appropriate microcosm bottles. Each volume of water added was measured gravimetrically using a top
loading balance and the weight was recorded. The Eagle Harbor and Lake Hartwell sample parameters
(including identification, weight of sediments and water in each of the serum bottles and duration of
incubation) are shown in Tables 2-2 and 2-3, respectively. After transfer of sediment and water into the
-------
serum bottles, each bottle was sealed with a butyl stopper and aluminum crimp. Figure 2-3 shows an
example of the two prepared serum bottles.
-------
BMNBRIDGE
I3.AND
APPROXIMATE BOUNDARY
OF CAP
EAGLE
HARBOR
EXPLANATION
Approximate Extent of 1993/1994 Cap
Approximate Extent of Study Area
SOURCE: MODIFIED FROM U.S. EPA AND U.S. ACE, 2000
n
DESIGNED BY
VM
DRAWN BY
DS
CHECKED BY
TW
250 0 500
SCALE IN FEET
. . . Putting Technology To Work
Figure 1-2.
Eagle Harbor Site Map
EAGLE HARBOR - BAINBRIDGE ISLAND, WASHINGTON
G464430-EPA61
AOC01.CDR
09/01
Figure 2-1. Eagle Harbor Site Map
-------
IN
BKG Phase 3-
Telemetry
Base Station
H
X
Transect O
Telemetry
Base Station
Transect M/N
BKG Phase 4
'--~ £
Transect N
r,(-Ai r IN Mil rs
Figure 2-2. Lake Hartwell Site Transect
-------
Killed controls were prepared for each time period. These killed control bottles were prepared
in a similar manner to the regular sample bottles with the exception of the addition of 1-mL of 8%
mercuric chloride (HgCl2) solution.
Figure 2-3. Microcosm Bottles: Lake Hartwell (left) and Eagle Harbor (right)
A total of 162 serum bottles were prepared and placed in an inverted fashion on an orbital
shaker table (New Brunswick Scientific; Series 25 Incubator-Shake) at approximately 50 rotations per
minutes (rpm). The microcosms were incubated at three temperature conditions: 10 °C, 22 °C and 37 °C.
In addition, two larger bottles (-750 mL) were prepared with Eagle Harbor and Lake Hartwell sediment
and site-specific water. A glass stem extending from the top of the bottle and a Teflon® union with a
Teflon®-lined septa was used as a gas sampling port for atmospheric gas analysis. Figure 2-4 shows the
two bottles containing sediment and water. The larger bottles were prepared with the same materials ratio
as the 125-mL bottles (100 g of sediment and 450 mL of site water) in the glove box under nitrogen gas.
The large bottles were kept in the orbital shaker at 50 rpm at 37 °C and were sampled for oxygen, CH4
and CO2 after 90-days of incubation.
2.4
Measurement of Gas Generation from Microcosm Bottles
The gas generated inside the 125-mL microcosm bottles was measured after 1, 3, 7, 14, 21, 30,
45, 60 and 90 days. The gas generated from each bottle could not be measured using a double syringe
because of the relatively small volume of gas that was produced in each bottle. Therefore, a single
syringe method was developed to quantify the small volume of gas generated inside the bottles. Five
milliliters of deionized water was added to a 10-mL glass syringe with its piston removed. A 22-guage
disposable needle was attached to the syringe. The number and duration of the bubbles released from the
microcosm bottles were recorded by a counter as the needle pierced the butyl seal at the mouth of the
12
-------
Figure 2-4. Larger Bottles with a Glass Stem
bottles (Figure 2-5). The number of bubbles was counted and the duration was measured with a stop
watch. The images of the gas bubbles were captured by a digital camera (Sony Smart Zoom DSC-P52)
and were digitized to calculate the average diameter. The volume of each bubble was determined to be
0.04163 mL.
The pH, oxidation-reduction potential (ORP) and dissolved oxygen (DO) were measured in the water of
the microcosm bottles after two months of incubation. About 2 to 3 mL of water was extracted from the
microcosm bottles with a syringe and added to a clean 40-mL volatile organic analysis (VOA) vial for
these measurements. An Omega probe and Symphony DO probe were used for pH and DO
measurements, respectively. Prior to the measurements, the pH probe was calibrated and an Orion ORP
probe was calibrated with quinhydrone solutions. A three point calibration was conducted with the pH
meter at a pH of 4, 7 and 10. The DO probe was air calibrated to reach the appropriate reading of 102.3%
saturation. The extraction of microcosm water samples and the analyses of these samples were conducted
in a glove box under nitrogen.
2.5 Column Study
A total of 11 columns were packed with sediment that was overlaid with site-specific water.
Seven of the columns used Eagle Harbor sediment and water. Lake Hartwell sediment and water
comprised the remaining columns. The columns were sparged with a mixture of CO2 and CFL, at two
different flow rates for 19 weeks (133 days). Polyurethane foam (PUF) tubes were used at the outlet of
the columns to entrap the organic compounds in the gas phase. The PUF samples were collected from the
columns after six weeks and at the end of the study (19 weeks); they were then analyzed for 38 priority
PAHs (Eagle Harbor) and 118 PCB congeners (Lake Hartwell). Sediment, cap material and water were
also analyzed for PAH and PCB analyses after 19 weeks.
13
-------
Figure 2-5. Measurement of Gas Bubbles from the Serum Bottles
14
-------
Table 2-2. Eagle Harbor Serum Bottle Test Parameters
Sample ID
EH-10-1-1
EH-10-1-2
EHCT-10-1-1
EH-25-1-1
EH-25-1-2
EHCT-25-1-1
EH-37-1-1
EH-37-1-2
EHCT-37-1-1
EH-10-3-1
EH-10-3-2
EHCT-10-3-1
EH-25-3-1
EH-25-3-2
EHCT-25-3-1
EH-37-3-1
EH-37-3-2
EHCT-37-3-1
EH-10-7-1
EH-10-7-2
EHCT-10-7-1
EH-25-7-1
EH-25-7-2
EHCT-25-7-1
EH-37-7-1
EH-37-7-2
EHCT-37-7-1
Description
Eagle Harbor Sediment and site water at 10 °C, Day 1
Eagle Harbor Sediment and site water at 10 °C, Day 1, duplicate
Eagle Harbor Sediment and site water at 10 °C, Day 1, kill control
Eagle Harbor Sediment and site water at 25 °C, Day 1
Eagle Harbor Sediment and site water at 25 °C, Day 1, duplicate
Eagle Harbor Sediment and site water at 25 °C, Day 1, kill control
Eagle Harbor Sediment and site water at 37 °C, Day 1
Eagle Harbor Sediment and site water at 37 °C, Day 1, duplicate
Eagle Harbor Sediment and site water at 37 °C, Day 1, kill control
Eagle Harbor Sediment and site water at 10 °C, Day 3
Eagle Harbor Sediment and site water at 10 °C, Day 3, duplicate
Eagle Harbor Sediment and site water at 10 °C, Day 3, kill control
Eagle Harbor Sediment and site water at 25 °C, Day 3
Eagle Harbor Sediment and site water at 25 °C, Day 3, duplicate
Eagle Harbor Sediment and site water at 25 °C, Day 3, kill control
Eagle Harbor Sediment and site water at 37 °C, Day 3
Eagle Harbor Sediment and site water at 37 °C, Day 3, duplicate
Eagle Harbor Sediment and site water at 37 °C, Day 3, kill control
Eagle Harbor Sediment and site water at 10 °C, Day 7
Eagle Harbor Sediment and site water at 10 °C, Day 7, duplicate
Eagle Harbor Sediment and site water at 10 °C, Day 7, kill control
Eagle Harbor Sediment and site water at 25 °C, Day 7
Eagle Harbor Sediment and site water at 25 °C, Day 7, duplicate
Eagle Harbor Sediment and site water at 25 °C, Day 7, kill control
Eagle Harbor Sediment and site water at 37 °C, Day 7
Eagle Harbor Sediment and site water at 37 °C, Day 7, duplicate
Eagle Harbor Sediment and site water at 37 °C, Day 7, kill control
Weight of Sediment
(g)
25.4
25.3
25.3
25.3
25.4
25.0
25.4
25.0
25.7
25.0
26.0
25.6
25.5
25.1
25.2
25.8
25.3
25.0
25.0
25.6
25.5
25.8
25.4
25.2
25.2
25.4
25.5
Volume of
Site water
(ml)
118.5
120.0
120.3
119.1
119.7
120.5
118.7
119.3
120.9
120.2
120.1
120.0
120.2
120.8
120.4
120.1
120.2
120.3
120.5
119.9
120.2
120.1
120.1
120.0
120.0
120.1
120.3
Incubation
Time
(Days)
1
o
5
7
-------
Table 2-2. Eagle Harbor Serum Bottle Test Parameters (Continued)
Sample ID
EH-10-14-1
EH-10-14-2
EHCT-10-14-1
EH-25-14-1
EH-25-14-2
EHCT-25-14-1
EH-37-14-1
EH-37-14-2
EHCT-37-14-1
EH-10-21-1
EH-10-21-2
EHCT-10-21-1
EH-25-21-1
EH-25-21-2
EHCT-25-21-1
EH-37-21-1
EH-37-21-2
EHCT-37-21-1
EH-10-30-1
EH-10-30-2
EHCT-10-30-1
EH-25-30-1
EH-25-30-2
EHCT-25-30-1
EH-37-30-1
EH-37-30-2
EHCT-37-30-1
Description
Eagle Harbor Sediment and site water at 10 °C, Day 14
Eagle Harbor Sediment and site water at 10 °C, Day 14, duplicate
Eagle Harbor Sediment and site water at 10 °C, Day 14, kill control
Eagle Harbor Sediment and site water at 25 °C, Day 14
Eagle Harbor Sediment and site water at 25 °C, Day 14, duplicate
Eagle Harbor Sediment and site water at 25 °C, Day 14, kill control
Eagle Harbor Sediment and site water at 37 °C, Day 14
Eagle Harbor Sediment and site water at 37 °C, Day 14, duplicate
Eagle Harbor Sediment and site water at 37 °C, Day 14, kill control
Eagle Harbor Sediment and site water at 10 °C, Day 21
Eagle Harbor Sediment and site water at 10 °C, Day 21, duplicate
Eagle Harbor Sediment and site water at 10 °C, Day 21, kill control
Eagle Harbor Sediment and site water at 25 °C, Day 21
Eagle Harbor Sediment and site water at 25 °C, Day 21, duplicate
Eagle Harbor Sediment and site water at 25 °C, Day 21, kill control
Eagle Harbor Sediment and site water at 37 °C, Day 21
Eagle Harbor Sediment and site water at 37 °C, Day 21, duplicate
Eagle Harbor Sediment and site water at 37 °C, Day 21, kill control
Eagle Harbor Sediment and site water at 10 °C, Day 30
Eagle Harbor Sediment and site water at 10 °C, Day 30, duplicate
Eagle Harbor Sediment and site water at 10 °C, Day 30, kill control
Eagle Harbor Sediment and site water at 25 °C, Day 30
Eagle Harbor Sediment and site water at 25 °C, Day 30, duplicate
Eagle Harbor Sediment and site water at 25 °C, Day 30, kill control
Eagle Harbor Sediment and site water at 37 °C, Day 30
Eagle Harbor Sediment and site water at 37 °C, Day 30, duplicate
Eagle Harbor Sediment and site water at 37 °C, Day 30, kill control
Weight of Sediment (g)
25.3
25.7
25.2
25.4
25.5
25.9
26.0
25.5
25.8
25.5
25.2
25.8
26.1
25.8
25.3
25.2
25.0
25.5
25.5
25.8
25.6
25.8
24.8
25.6
25.0
25.4
25.8
Volume of
Site Water
(ml)
120.1
120.3
120.3
120.1
120.0
120.2
120.1
119.9
120.1
120.1
120.3
120.1
120.0
120.3
120.0
120.5
120.2
120.2
120.1
120.4
120.7
120.0
120.7
120.3
120.2
120.0
120.6
Incubation
Time
(Days)
14
21
30
-------
Table 2-2. Eagle Harbor Serum Bottle Test Parameters (Continued)
Sample
EH-10-45-1
EH-10-45-2
EHCT-10-45-1
EH-25-45-1
EH-25-45-2
EHCT-25-45-1
EH-37-45-1
EH-37-45-2
EHCT-37-45-1
EH-10-60-1
EH-10-60-2
EHCT-10-60-1
EH-25-60-1
EH-25-60-2
EHCT-25-60-1
EH-37-60-1
EH-37-60-2
EHCT-37-60-1
EH-10-90-1
EH-10-90-2
EHCT-10-90-1
EH-25-90-1
EH-25-90-2
EHCT-25-90-1
EH-37-90-1
EH-37-90-2
EHCT-37-90-1
Description
Eagle Harbor Sediment and site water at 10 °C, Day 45
Eagle Harbor Sediment and site water at 10 °C, Day 45, duplicate
Eagle Harbor Sediment and site water at 10 °C, Day 45, kill control
Eagle Harbor Sediment and site water at 25 °C, Day 45
Eagle Harbor Sediment and site water at 25 °C, Day 45, duplicate
Eagle Harbor Sediment and site water at 25 °C, Day 45, kill control
Eagle Harbor Sediment and site water at 37 °C, Day 45
Eagle Harbor Sediment and site water at 37 °C, Day 45, duplicate
Eagle Harbor Sediment and site water at 37 °C, Day 45, kill control
Eagle Harbor Sediment and site water at 10 °C, Day 60
Eagle Harbor Sediment and site water at 10 °C, Day 60, duplicate
Eagle Harbor Sediment and site water at 10 °C, Day 60, kill control
Eagle Harbor Sediment and site water at 25 °C, Day 60
Eagle Harbor Sediment and site water at 25 °C, Day 60, duplicate
Eagle Harbor Sediment and site water at 25 °C, Day 60, kill control
Eagle Harbor Sediment and site water at 37 °C, Day 60
Eagle Harbor Sediment and site water at 37 °C, Day 60, duplicate
Eagle Harbor Sediment and site water at 37 °C, Day 60, kill control
Eagle Harbor Sediment and site water at 10 °C, Day 90
Eagle Harbor Sediment and site water at 10 °C, Day 90, duplicate
Eagle Harbor Sediment and site water at 10 °C, Day 90, kill control
Eagle Harbor Sediment and site water at 25 °C, Day 90
Eagle Harbor Sediment and site water at 25 °C, Day 90, duplicate
Eagle Harbor Sediment and site water at 25 °C, Day 90, kill control
Eagle Harbor Sediment and site water at 37 °C, Day 90
Eagle Harbor Sediment and site water at 37 °C, Day 90, duplicate
Eagle Harbor Sediment and site water at 37 °C, Day 90, kill control
Weight of Sediment (g)
25.1
25.1
25.4
25.3
25.8
25.6
25.4
25.0
25.5
25.6
25.5
25.4
25.1
25.5
25.5
25.4
25.4
25.1
26.0
25.8
25.8
25.2
25.2
25.4
25.2
25.6
25.4
Volume of
Site Water
(ml)
120.4
120.0
120.2
120.2
120.1
120.0
120.0
120.1
120.2
120.2
120.0
120.1
120.3
120.5
120.0
120.4
120.5
120.1
120.1
120.2
120.1
121.1
120.3
120.4
120.1
120.2
120.0
Incubation
Time
(Days)
45
60
90
-------
Table 2-3. Lake Hartwell Serum Bottle Test Parameters
Sample Id
LH-10-1-1
LH-10-1-2
LHCT-10-1-1
LH-25-1-1
LH-25-1-2
LHCT-25-1-1
LH-37-1-1
LH-37-1-2
LHCT-37-1-1
LH-10-3-1
LH-10-3-2
LHCT-10-3-1
LH-25-3-1
LH-25-3-2
LHCT-25-3-1
LH-37-3-1
LH-37-3-2
LHCT-37-3-1
LH-10-7-1
LH-10-7-2
LHCT-10-7-1
LH-25-7-1
LH-25-7-2
LHCT-25-7-1
LH-37-7-1
LH-37-7-2
LHCT-37-7-1
Description
Lake Hartwell Sediment and site water at 10 °C, Day 1
Lake Hartwell Sediment and site water at 10 °C, Day 1, duplicate
Lake Hartwell Sediment and site water at 10 °C, Day 1, kill control
Lake Hartwell Sediment and site water at 25 °C, Day 1
Lake Hartwell Sediment and site water at 25 °C, Day 1, duplicate
Lake Hartwell Sediment and site water at 25 °C, Day 1, kill control
Lake Hartwell Sediment and site water at 37 °C, Day 1
Lake Hartwell Sediment and site water at 37 °C, Day 1, duplicate
Lake Hartwell Sediment and site water at 37 °C, Day 1, kill control
Lake Hartwell Sediment and site water at 10 °C, Day 3
Lake Hartwell Sediment and site water at 10 °C, Day 3, duplicate
Lake Hartwell Sediment and site water at 10 °C, Day 3, kill control
Lake Hartwell Sediment and site water at 25 °C, Day 3
Lake Hartwell Sediment and site water at 25 °C, Day 3, duplicate
Lake Hartwell Sediment and site water at 25 °C, Day 3, kill control
Lake Hartwell Sediment and site water at 37 °C, Day 3
Lake Hartwell Sediment and site water at 37 °C, Day 3, duplicate
Lake Hartwell Sediment and site water at 37 °C, Day 3, kill control
Lake Hartwell Sediment and site water at 10 °C, Day 7
Lake Hartwell Sediment and site water at 10 °C, Day 7, duplicate
Lake Hartwell Sediment and site water at 10 °C, Day 7, kill control
Lake Hartwell Sediment and site water at 25 °C, Day 7
Lake Hartwell Sediment and site water at 25 °C, Day 7, duplicate
Lake Hartwell Sediment and site water at 25 °C, Day 7, kill control
Lake Hartwell Sediment and site water at 37 °C, Day 7
Lake Hartwell Sediment and site water at 37 °C, Day 7, duplicate
Lake Hartwell Sediment and site water at 37 °C, Day 7, kill control
Weight of Sediment (g)
25.5
25.2
25.1
25.1
25.4
25.0
25.0
25.0
25.2
25.2
25.4
25.2
25.3
25.6
25.2
25.0
25.1
25.2
25.6
25.5
25.1
25.4
26.0
25.3
25.5
24.9
25.3
Volume of
Site water
(ml)
115.5
115.0
115.1
115.0
115.2
115.3
115.1
115.2
115.1
115.1
115.2
115.3
115.4
115.1
115.3
115.1
115.4
115.0
115.3
115.0
115.4
115.1
115.7
115.2
115.2
115.4
115.0
Incubation
Time (Days)
1
3
7
-------
Table 2-3. Lake Hartwell Serum Bottle Test Parameters (Continued)
Sample ID
LH-10-14-1
LH-10-14-2
LHCT-10-14-1
LH-25-14-1
LH-25-14-2
LHCT-25-14-1
LH-37-14-1
LH-37-14-2
LHCT-37-14-1
LH-10-21-1
LH-10-21-2
LHCT-10-21-1
LH-25-21-1
LH-25-21-2
LHCT-25-21-1
LH-37-21-1
LH-37-21-2
LHCT-37-21-1
LH-10-30-1
LH-10-30-2
LHCT-10-30-1
LH-25-30-1
LH-25-30-2
LHCT-25-30-1
LH-37-30-1
LH-37-30-2
LHCT-37-30-1
Description
Lake Hartwell Sediment and site water at 10 °C, Day 14
Lake Hartwell Sediment and site water at 10 °C, Day 14, duplicate
Lake Hartwell Sediment and site water at 10 °C, Day 14, kill control
Lake Hartwell Sediment and site water at 25 °C, Day 14
Lake Hartwell Sediment and site water at 25 °C, Day 14, duplicate
Lake Hartwell Sediment and site water at 25 °C, Day 14, kill control
Lake Hartwell Sediment and site water at 37 °C, Day 14
Lake Hartwell Sediment and site water at 37 °C, Day 14, duplicate
Lake Hartwell Sediment and site water at 37 °C, Day 14, kill control
Lake Hartwell Sediment and site water at 10 °C, Day 21
Lake Hartwell Sediment and site water at 10 °C, Day 21, duplicate
Lake Hartwell Sediment and site water at 10 °C, Day 21, kill control
Lake Hartwell Sediment and site water at 25 °C, Day 21
Lake Hartwell Sediment and site water at 25 °C, Day 21, duplicate
Lake Hartwell Sediment and site water at 25 °C, Day 21, kill control
Lake Hartwell Sediment and site water at 37 °C, Day 21
Lake Hartwell Sediment and site water at 37 °C, Day 21, duplicate
Lake Hartwell Sediment and site water at 37 °C, Day 21, kill control
Lake Hartwell Sediment and site water at 10 °C, Day 30
Lake Hartwell Sediment and site water at 10 °C, Day 30, duplicate
Lake Hartwell Sediment and site water at 10 °C, Day 30, kill control
Lake Hartwell Sediment and site water at 25 °C, Day 30
Lake Hartwell Sediment and site water at 25 °C, Day 30, duplicate
Lake Hartwell Sediment and site water at 25 °C, Day 30, kill control
Lake Hartwell Sediment and site water at 37 °C, Day 30
Lake Hartwell Sediment and site water at 37 °C, Day 30, duplicate
Lake Hartwell Sediment and site water at 37 °C, Day 30, kill control
Weight of Sediment (g)
26.1
25.8
25.6
25.4
25.4
25.8
25.3
25.3
25.8
26.0
25.3
25.1
25.1
25.5
25.2
25.1
25.5
25.2
25.5
25.5
25.5
26.0
25.6
25.5
25.5
25.8
25.3
Volume of
Site Water
(ml)
114.8
115.3
115.4
115.3
115.3
115.2
115.3
115.2
115.4
114.8
115.2
115.4
115.1
115.6
115.0
115.3
115.2
115.1
115.8
115.3
115.0
115.1
115.5
115.1
115.2
115.2
114.8
Incubation
Time
(Days)
14
21
30
-------
Table 2-3. Lake Hartwell Serum Bottle Test Parameters (Continued)
Sample ID
LH-10-45-1
LH-10-45-2
LHCT-10-45-1
LH-25-45-1
LH-25-45-2
LHCT-25-45-1
LH-37-45-1
LH-37-45-2
LHCT-37-45-1
LH-10-60-1
LH-10-60-2
LHCT-10-60-1
LH-25-60-1
LH-25-60-2
LHCT-25-60-1
LH-37-60-1
LH-37-60-2
LHCT-37-60-1
LH-10-90-1
LH-10-90-2
LHCT-10-90-1
LH-25-90-1
LH-25-90-2
LHCT-25-90-1
LH-37-90-1
LH-37-90-2
LHCT-37-90-1
Description
Lake Hartwell Sediment and site water at 10 °C, Day 45
Lake Hartwell Sediment and site water at 10 °C, Day 45, duplicate
Lake Hartwell Sediment and site water at 10 °C, Day 45, kill control
Lake Hartwell Sediment and site water at 25 °C, Day 45
Lake Hartwell Sediment and site water at 25 °C, Day 45, duplicate
Lake Hartwell Sediment and site water at 25 °C, Day 45, kill control
Lake Hartwell Sediment and site water at 37 °C, Day 45
Lake Hartwell Sediment and site water at 37 °C, Day 45, duplicate
Lake Hartwell Sediment and site water at 37 °C, Day 45, kill control
Lake Hartwell Sediment and site water at 10 °C, Day 60
Lake Hartwell Sediment and site water at 10 °C, Day 60, duplicate
Lake Hartwell Sediment and site water at 10 °C, Day 60, kill control
Lake Hartwell Sediment and site water at 25 °C, Day 60
Lake Hartwell Sediment and site water at 25 °C, Day 60, duplicate
Lake Hartwell Sediment and site water at 25 °C, Day 60, kill control
Lake Hartwell Sediment and site water at 37 °C, Day 60
Lake Hartwell Sediment and site water at 37 °C, Day 60, duplicate
Lake Hartwell Sediment and site water at 37 °C, Day 60, kill control
Lake Hartwell Sediment and site water at 10 °C, Day 90
Lake Hartwell Sediment and site water at 10 °C, Day 90, duplicate
Lake Hartwell Sediment and site water at 10 °C, Day 90, kill control
Lake Hartwell Sediment and site water at 25 °C, Day 90
Lake Hartwell Sediment and site water at 25 °C, Day 90, duplicate
Lake Hartwell Sediment and site water at 25 °C, Day 90, kill control
Lake Hartwell Sediment and site water at 37 °C, Day 90
Lake Hartwell Sediment and site water at 37 °C, Day 90, duplicate
Lake Hartwell Sediment and site water at 37 °C, Day 90, kill control
Weight of Sediment (g)
25.8
25.2
25.1
25.9
26.0
26.1
25.9
25.2
25.4
25.0
25.6
25.8
25.1
25.4
25.7
25.3
25.2
25.3
25.1
25.3
25.8
25.1
25.6
25.8
25.4
25.6
25.7
Volume of
Site Water
(ml)
115.4
115.8
115.2
115.0
115.1
115.1
115.7
115.6
115.1
115.0
115.0
115.2
115.5
115.2
115.2
115.3
115.6
115.0
115.1
115.3
115.2
115.6
115.3
115.1
115.6
115.1
115.3
Incubation
Time
(Days)
45
60
90
to
o
-------
2.5.1 Construction of Gas Ebullition Columns
The Eagle Harbor and Lake Hartwell columns were operated separately in laboratory hoods.
Two-foot long glass columns, 2 inches in diameter with three side ports were used to construct the
experiments. Two of the ports were positioned 4 inches from the column ends and another port was in the
center of the column. The end of each column was threaded for affixing tube and pressure fittings.
Teflon® end caps were screwed into each end of the column. A fritted glass disc was attached
to the end of the cap, which was screwed onto the base of the columns. The fritted glass disc was used to
diffuse the sparged gas from a Class A, 1200 lb/inch2 (psi) cylinder (Scott Speciality Gas, Michigan)
through the column. The gas mixture was 60% CIL, and 40% CO2. The gas composition was selected
based on field research and results. Clamps were used to secure the columns to ring stands in the hood.
A manifold was constructed out of 1/8 inch stainless steel tube for both the Eagle Harbor and Lake
Hartwell columns. In the case of the Eagle Harbor columns the manifold consisted of partitioning the
feed line from the cylinder into seven lines that led to the individual columns in the hood. The Lake
Hartwell manifold consisted of four lines. A micro-flow meter was attached to each line from the
manifold. A sensitive needle valve was attached to each line before the micro-flow meter. The needle
valve was capable of making minute adjustments in the gas flow rate. A one-way flow check valve was
attached to the pipe just before each column to prevent backflow of the feed lines from the water in the
column. Two PUF tubes were attached together in series at the top of the column. The second PUF tube
in series was used to capture contaminant break through the first PUF cartridge. The installation and
connection steps involved bending % inch tubing into a "U" shape. The tubing was secured into the
Teflon® end caps with a % inch male National Pipe Thread (NPT) fitting. These end caps were then
screwed into place at the top of the column. Tygon™ tubing was used to connect the tapered end of the
PUF tube to the % inch tubing. The other end of the Tygon™ tube was pulled tightly over the % inch
stainless steel pipe. Silicon sealant and a tie strip were used to secure the pipe and the Tygon™ tube
together. Two PUF tubes were connected in series by connecting the open ends together with % inch
Tygon™ tubing. A one inch section of % inch Tygon™ tubing was placed into boiling water for 30-
seconds in order to make the tubing malleable. The Tygon™ section was then placed over the open ends
of the PUF tubes and allowed to cool. The Tygon™ cooled and shrunk around the PUF tubes creating a
tight connection. In places where Tygon™ tube was used glass ends were fixed so that they were flush to
each other to ensure that the Tygon™ tube was not exposed to the air flow, minimizing contaminant
sorption onto the tubing.
The side ports of the columns were plugged using % inch diameter, threaded Teflon® stoppers.
The center port, 12 inches from the base of the column, had a Teflon® stopper with a Teflon®-lined septa
opening. Column water was collected from the center port for measurements, such as pH, ORP, DO and
turbidity. A schematic diagram of the Eagle Harbor columns is shown in Figure 2-6. A similar setup was
used for the four Lake Hartwell columns. Figures 2-7 and 2-8 show the actual Eagle Harbor and Lake
Hartwell columns during operation.
2.5.2 Packing of Columns
Measured amounts of pea gravel were added 3-inches from the base of the column with a 500-
mL wide mouth beaker. An aluminum mesh disc 2-inches in diameter was added after the pea gravel in
order to separate the pea gravel and sediment layers. Wet packing of sediment was used for all of the
columns. Measured amounts of sediment were added to achieve a height of 3-inches. The sediment was
added into the column by using a large spatula. The PAH concentration of Eagle Harbor sediment was
approximately 386,000 ng/g-dry total PAH. The Lake Hartwell sediment concentration was deemed
21
-------
Low Flow (6.5 ml/min.)
High Flow (18.7 ml/min.)
1/4" Steel Pipe
to
to
PUF Tubes in
Series
Site Vteter
Sediment
Pea Gravel
/Needle
3 / Valve
$r
Regulator
Check
Valve
60% CH4
40% CO,
EH_SETUP.CDR
Figure 2-6. Schematic Diagram of Eagle Harbor Column
-------
insufficient to ensure detectable gas phase concentrations during column operations; approximately 2800
ng/g dry total PCB. Therefore, it was spiked with 2 (ig/g of Aroclor mix 2. This Aroclor mix was chosen
because it best represented the congener makeup of the Lake Hartwell sediment. Two ampoules of
Aroclor mix 2 were added to 300 g of Lake Hartwell sediment in a 1-L high density polyethylene (HDPE)
bottle. The bottle was tumbled overnight at 29 rpm in a rotary apparatus (Associated Design & Mfg. Co.,
Virginia, Model 3 740-12-BRE).
Figure 2-7. Photograph of Eagle Harbor Columns
Figure 2-8. Photograph of Lake Hartwell Columns
Additional aluminum mesh discs were placed over the sediment for the columns designated for
the cap. Three of the seven Eagle Harbor Columns had the cap. Two-inches of cap material were added
in measured amounts with a spatula. The weights of the pea gravel, sediment and cap material for the
Eagle Harbor and Lake Hartwell columns are listed in Table 2-4. Eagle Harbor and Lake Hartwell water
was added to the columns using a 1000-mL graduated cylinder. Each column had 750-mL of site-specific
water.
23
-------
Table 2-4. Column Parameters of Eagle Harbor and Lake Hartwell Setup
Eagle Harbor
Column
No.
1
2
3
4
5
6
7
Column
Description
Low flow, uncapped
Low Flow, capped
Low flow, uncapped
Low flow, capped
High flow, uncapped
High Flow, capped
High Flow, uncapped
Pea Gravel
(g)
208.5
196.0
197.5
182.5
212.0
207.0
232.5
Sediment
(g)
290.5
342.0
272.0
242.0
253.0
248.0
270.5
Cap (g)
NA
200.5
NA
211.5
NA
215.0
NA
Corrected
Flow
(ml/min)
6.5
18.7
Methane
Flux (L/m2-
d)
4618
13280
Lake Hartwell
8
9
10
11
Low flow
High flow
Low flow, PCB spiked
Low flow, PCB spiked
181.5
179.0
212.5
177.0
149.0
150.0
144.0
142.5
NA
NA
NA
NA
6.5
18.7
6.5
4618
13280
4618
2.5.3 Variation of Gas Flow through the Columns
Two flow conditions, high and low, were maintained for the Eagle Harbor and Lake Hartwell columns.
The flow conditions were controlled by throttling the control valves. The low flow condition was
selected by throttling the valve measured by the microflow meters. The high level flow conditions were
controlled via the maximum opening of the control valve that can measure flow by the microflow meter.
Microflow meters (Gilmont Instruments, Illinois) have a scale from 0 to 100 which corresponds to a
percentage of the maximum flow rate the flow meter can measure. The Eagle Harbor and one of the Lake
Hartwell microflow meters had a range from 0 to 15 mL/min for air. Three of the Lake Hartwell flow
meters used for the low flow condition had a range from 0 to 10 mL/min for air. The low flow columns
were set at 30% of the maximum measurable flow rate and the high flow columns were set at 85% for the
0 to 15 mL/min flow meters. The three low flow Lake Hartwell columns using the 0 to 10 mL/min
microflow meters were set at 56% in order to correspond to the same low condition flow rate as the Eagle
Harbor columns. The actual corrected flow rate was calculated with correction factors which take into
account the type of gas used and the pressure of the supplied gas. The correction factors were determined
from a chart supplied by the vendor. The correction factor for CHt was 1.35 and the correction factor for
CO2 was 0.81. The pressure correction was 1.29 as the gas was supplied at 10 psig from the gas regulator
(Table 2-5).
Table 2-5. Correction Factors for the Gas Mixture and Pressure
Percentage
60
40
Gas
CH4
CO2
Flow Correction
Factors
1.35
0.81
10 psig Regulated
Pressure
1.29
Total Correction
Factor
1.46
The calculated correction factor for a 60% CFL, and 40% CO2 mixture supplied at 10 psig was
1.46 (shown in Equation 1). Thus, at 30% of the maximum measurable flow rate of 15 mL/min, the
actual flow rate of the gas mixture was 6.5 mL/min.
(^H4Factor) • 0.6 + (CO2Factor) • 0.4 1(PressureFactor) = 1.46
24
(Equation 1)
-------
2.5.4 Analyses of Column Materials
After six weeks of continuous gas sparging through the columns, the PUF filters were removed from the
top of the columns and sent to Battelle's laboratory at Duxbury, Massachusetts for PCBs and PAH
analyses. A new set of PUFs were immediately replaced at the outlet of the columns. After 19 weeks of
continuous gas sparging operation of the columns, the gas supply was turned off and the manifold was
disconnected from the column feed lines. The standing column water at the top of the sediment was
carefully decanted into 1-L amber bottle. The sediment and cap (wherever applicable) were removed
with a long armed spatula and added into 250-mL glass bottles with a Teflon®-lined cap. The glass
bottles were wrapped in aluminum foil. The amounts of water, sediment and cap material recovered were
measured gravimetrically. The water, sediment, cap material and PUFs were sent for analyses at
Battelle's Duxbury laboratory. In Figure 2-9, typical Eagle Harbor sample containers are shown.
Figure 2-9. Eagle Harbor Water, Cap and Sediment (after 19-weeks)
2.5.5 Measurements of pH, ORP, DO and Turbidity
The pH, ORP, DO and turbidity were measured for overlying water in the columns and the
porewater from the sediment. A 50-mL syringe was used to collect approximately 25-mL from the side
port of the column as shown in Figure 2-10. The turbidity was measured first using a HACK 2300DR
followed by the ORP and DO measurements. The pH, ORP and DO measurements were conducted
inside the glove box under a nitrogen environment. All of the pH and DO probes were calibrated under
ambient conditions and the ORP probe was checked using a quinhydrone solution. These measurements
were also conducted for the sediment porewater. Porewater was collected by centrifuging 10-grams of
column sediment in a centrifuge tube for 45 minutes at 3250 rpm (Bekman Centrifuge). The probes were
placed in centrifuge tubes and dipped into the porewater that had been separated from the precipitated
sediment.
2.6 Analytical Techniques: PCBs and PAH
2.6.1 Sediment Sample Processing
Sediment samples were extracted for PCB congeners or PAHs following Battelle SOP 5-192.
Approximately 30 g of wet sediment were mixed with sodium sulfate (a drying agent), fortified with
surrogate internal standards (SIS), and extracted three times with methylene chloride using shaker table
techniques. The combined extracts were dried over anhydrous sodium sulfate and cleaned using alumina
column (Battelle SOP 5-329), activated copper (Battelle SOP 5-328) and size exclusion high performance
liquid chromatography (HPLC) (Battelle SOP 5-191). The post-HPLC extract was solvent-exchanged to
n-hexane, concentrated to approximately 1 mL, and fortified with a set of internal standards (IS).
25
-------
Figure 2-10. Removal of Column Water for pH, ORP, DO and Turbidity Measurements
2.6.2 PUF Sample Processing
PUF samples were extruded from their cartridges into pre-cleaned Teflon® extraction vessels and
extracted like solids, following procedures defined in Battelle SOP 5-192. The initial extraction was
performed in n-hexane (as opposed to methylene chloride). Prior to alumina column cleanup, the extract
was solvent exchanged into methylene chloride; the extract cleanup proceeded in the same manner as in
the sediment processing section.
2.6.3 Large Volume (>1 L) Water Sample Processing
Water samples were extracted for PCB congeners or PAHs following Battelle SOP 5-200.
Approximately 1 L of the water sample was fortified with SIS and extracted three times with methylene
chloride using separatory funnel techniques. The combined extract was dried over anhydrous sodium
sulfate and cleaned using alumina column chromatography (Battelle SOP 5-329), activated copper
(Battelle SOP 5-328), and HPLC (Battelle SOP 5-191). The post-HPLC extract was solvent-exchanged
to n-hexane, concentrated to approximately 0.5-mL, and fortified with IS.
2.6.4 Small Volume (<0.5 L) Water Sample Processing
Water samples were centrifuged to remove particulates and extracted for PCB congeners or PAHs
following Battelle SOP 5-200. Approximately 125 mL of the water sample was fortified with SIS and
extracted three times with methylene chloride using separatory funnel techniques. The amount of solvent
was adjusted to reflect the volume of water extracted. The combined extract was dried over anhydrous
sodium sulfate and cleaned using alumina column chromatography (Battelle SOP 5-329), activated
copper (Battelle SOP 5-328), and HPLC (Battelle SOP 5-191). The post-HPLC extract was solvent-
exchanged to n-hexane, concentrated to approximately 0.25-mL, and fortified with IS.
2.6.5 Instrumental Analysis
Gas chromatography/mass spectrometry (GC/MS) analysis for semi-volatile organics (e.g., PAH) was
performed according to Battelle SOP 5-157, Identification and Quantitation of Polynuclear Aromatic
26
-------
Hydrocarbons (PAH) by Gas Chromatography/Mass Spectrometry. This method is based on SW846
Method 8270C (U.S. EPA, 1996). The 8270M target compounds were determined using high-resolution
capillary GC/MS. The GC/MS analysis for PCB congeners was performed following protocols defined in
Battelle SOP 5-315, Identification and Quantification of Poly chlorinated Biphenyl Congeners (PCB),
PCB Homologues, and Chlorinated Pesticides by Gas Chromatography/Mass Spectroscopy in the
Selected Ion Monitoring (SIM) Mode. The method protocols in this Battelle SOP are based on key
components of the PCB congener analysis approach described in U.S. EPA Method 1668A (U.S. EPA
1999), using SW846 8270M as the base method. The analytical systems are comprised of a Hewlett-
Packard (HP) 6890 GC equipped with an electronic pressure controlled (EPC) inlet and an HP 5973 mass
selective detector (MSB) operating in the SIM mode to achieve the necessary sensitivity and specificity.
The analytical systems are tuned with perfluorotributylamine (PFTBA), calibrated with a
minimum of a six-point calibration consisting of each individual target compound with an approximate
analyte concentration range of 0.005 to 10 ng/(iL for semi-volatile s and 0.002 to 1 ng/(iL for PCB
congeners. The validity of the initial calibration is monitored with a continuing calibration check analysis
at least every 12 hours. Quantification of individual target compounds is performed by the method of
internal standards, using the relative response factors versus the retention indices (RIs) (the data are not
surrogate corrected).
2.7 Analytical Techniques: Gas Analysis
The samples were received at Microseeps Inc.'s (Pittsburgh, Pennsylvania) laboratory in the
sealed serum vial in which they were prepared. It was unknown in the planning stage whether there
would be an excess pressure generated in the headspace, or if the headspace pressure would simply be
atmospheric. To be conservative, it was decided to assume that no excess pressure would be generated
and to employ a headspace from which a 10 mL aliquot could be removed.
The samples were sub-sampled by insertion of a locking, gas-tight syringe through the septum.
Prior to insertion the plunger of the syringe was completely depressed and the syringe was fit with a 21-
gauge stainless-steal disposable needle. The needle was inserted through the septum and the plunger was
allowed to expand to release any excess pressure. This is how the excess pressure was measured.
Since there was no excess pressure, the plunger was drawn back to 10 mL. The syringe was
then locked, effectively closing the path between the syringe barrel and the headspace. The plunger was
then released and under atmospheric pressure the volume of the gas was somewhat less than 10 mL. The
lock was opened, and the plunger drawn to a number above 10, until an appropriate mass of sub-sample
was collected.
For CO2, CH4 and oxygen concentration measurements the aliquot was then directly injected
onto a GC column. The GC was operated and the results quantified according to SOP-AM20Gax.
Reporting limits, quality control parameters, and so on are discussed in that SOP.
27
-------
Section 3.0 RESULTS AND DISCUSSION
3.1 Microcosm Study
The main objective of the microcosm study was to determine the amount of gas generated at
various times (1, 3, 7, 14, 21, 30, 45, 60, 90-days) and under different temperature conditions. The site-
specific properties of sediments and water from the two sites (Eagle Harbor and Lake Hartwell) are
expected to have an impact on the amount of gas generated.
Tables 3-1 and 3-2 show the number of bubbles generated, corresponding gas volume, and
composition of gas obtained from the headspace gas analysis. Separate sets of sacrificial bottles were
used for gas volume measurement and composition analyses.
The Eagle Harbor serum bottles showed minimal or no measurable gas measured at 10°C and
25 °C. The maximum volume of gas generation was observed after 3-days at 25 °C, where 0.54 and 0.79
mL gas volume were measured in duplicate samples. There were measurable amounts of gas generated
from the kill controlled samples at 10°C and 25°C during the early sampling time intervals. However, as
the study progressed to 90-days, no gas was measured in the killed controls. At 37 °C, gas was measured
at all time intervals.
There were no significant levels of the measured gases in the headspace of any of the Eagle Harbor
sediment samples that were incubated for 14 days and 90 days. The killed controls generated increased
levels of CCh in the headspace, which was similar to the Lake Hartwell bottles. There was a decrease in
oxygen concentration in the headspace from 10 °C to 25 °C for the Eagle Harbor sediment bottles that
were incubated for 90 days.
At 10 °C, no gas was measured from the Lake Hartwell bottles during all sampling time events.
At room temperature (25 °C), about 0.4 mL of gas was measured at both 30 and 60-days of incubation.
However, over the duration of the study, no significant change in gas generation with time was observed
for the samples incubated at 10 °C to 25 °C. Though gas was generated from the day-3 killed control
bottle, subsequent measurements of sacrificial killed control bottles showed no gas generation. At 37 °C,
gas was measured in each bottle including the kill controls during each time withdrawal events. The gas
measured from the bottles at 37 °C might be due to the water vapor generated at higher temperatures
and/or due to the higher biological activities at a higher incubation temperature. However, no change in
gas generation was observed with an increase in incubation time from day 1 to day 90. In Figure 3-1, the
average gas measurement and the kill control for Lake Hartwell bottles are plotted.
After incubation of 14-days and 90-days, the 125-mL serum bottles were packed in wet ice and
sent for headspace analysis. The percentage of CH* measured in the headspace was 3.1% and 2.4 % for
the duplicate bottles and 1.9% for the kill control for the day 14 bottles incubated at 37 °C. The
percentage of CH4 was below detection limits (<0.200%) at 10 °C and 25 °C. Thus, it appears that the
higher temperatures facilitated the production of CF^ in the Lake Hartwell bottles after 14-days.
Furthermore, there was a decrease in oxygen and an increase in CO2 and CFL in the 14-day bottles as the
temperature increased from 10 °C to 37 °C. CO2 was the prevalent gas measured in the kill controls at all
temperature conditions. However, it is not clear how the addition of mercuric chloride in the killed
control bottles at all three temperature conditions caused an increased production of CO2 compared with
the bottles with no mercuric chloride added.
28
-------
There was an increase in CIL, production from 14-days to 90-days for the bottles at 25 °C. Also, the
headspace of larger bottles that were incubated for 90 days at 37 °C contained mostly CO2 and oxygen.
3.1.1 Sediment and Water Analysis of Microcosm Bottles
After an incubation of 90 days, the serum bottles containing sediments and water from Eagle
Harbor Lake and Hartwell were sent to Battelie's Duxbury laboratory. The sediment and water in the
bottles were analyzed for PAHs in the Eagle Harbor samples and PCBs in the Lake Hartwell samples.
In Figure 3-1, the concentrations of PAHs (ng/g-dry) in the Eagle Harbor sediment were plotted
at various incubation conditions. The PAHs are listed on the x-axis from left to right from lower to
higher molecular weight. The sediment at 10 °C, 25 °C, 37 °C and non-incubated are adjacent to each
other in the bar diagram. There is a higher concentration of PAH in the sediment as the temperature
increases from 10 °C to 37 °C. This pattern holds true from low to high molecular weight of PAH
compounds. The concentration profile of the PAHs from low to high molecular weight concentrations
remains unchanged due to temperature effects. For example, the average concentration of phenanthrene
is the highest for all temperatures and also for the non-incubated sediment.
The water in the 90-day serum bottles containing Eagle Harbor sediment was also analyzed for
PAHs. In Figure 3-2, the PAH concentrations (ng/L) were at various incubation conditions. As with the
sediment plot, the PAHs are arranged on the x-axis from low to high molecular weight. An inverse
relationship is observed in comparison with the water. The concentration of PAH in the water decreases
from low temperature (10 °C) to higher temperature 37°C. This trend is consistent as the PAH molecular
weight increases.
The Lake Hartwell sediment was analyzed for 118 congeners of PCBs. The bar diagram of
PCB concentrations (ng/g) versus various congeners for incubation conditions were plotted in Figure 3-3.
After incubation for 90-days, the concentration of PCBs was higher at the lower temperature (10°C)
sediment than the sediment incubated at higher temperatures (25 °C and 37 °C).
Figure 3-3 also shows the change in PCB concentrations (ng/L) in water at the various
incubation temperatures. The PCB concentration in water was lower for the 10 °C incubated sediment
than that of the higher temperatures. This trend is opposite of the Lake Hartwell sediment.
3.1.2 pH and Redox Potential of Microcosm Bottles
The pH and redox potential of water in the incubated serum bottles containing Eagle Harbor
and Lake Hartwell sediments were conducted inside a glove box under a nitrogen environment. A 2-mL
aliquot of water was extracted from the bottles using a 22-guage needle. A more detailed description of
the pH and ORP procedure is described in the Materials and Methods section. In Table 3-3, the pH and
ORP values were tabulated for the serum bottles containing the Eagle Harbor and Lake Hartwell
sediments and site-specific water. Incubation temperatures of the serum bottles were also shown in the
table. At the end of incubation, the pH of the water in Eagle Harbor varied between 7.3 and 8.3. The
ORP of the same bottles varied between -210 to -240 mV (i.e., Eh varied from -10 to -40 mV) (Figure 3-
4). These ORP values indicated that these bottles were at methanogenic conditions at the end of the
incubation period. The change in incubation temperature did not impact the changes in pH and ORP of
the equilibrated water at the end of the incubation period. The killed control bottles containing Eagle
Harbor sediment that were spiked with 1-mL of 8% mercuric chloride showed relatively lower pH and
higher ORP values than the sample bottled. The ORP of the killed control bottles incubated at 10 °C and
25 °C ranged between 132 to 140 mV indicating the presence of aerobic environment in the microcosm
bottles in the absence of biological activities. The measured ORP value of the killed control bottle at
29
-------
3.O
2.5
£ 2~°
I 1-5
3
^ 1.O
O.S
Eagle Harbor Gsts Generation Sampling at 1O "C
-Average
- Control
O
1O 2
3O 4O SO 6Q TO SO
Time fDays)
9O
2.5
=- 2.Q
O
1.5
> 1.0
0.5
a,.a
HartK>r Generation Sampling at: 25
Control
a
to
4Q
7D
9O
3.0
2.5
2.0
1.5
1.0
Q.5
Q..Q
Eagle Hartx>r G-as Generation Sarnpring at 37 JC
Average
Control
1O
2O
3Q
4Q
5Q
SO
7D
SO
9D
Fig 3-1. Eagle Harbor Gas Generation at 10°C, 25°C, and 37°C
30
-------
3
2.5
g
| 1.5
•5
> 1
O-5
O
C
Lake Hartwell Gas Generation Sampling at 1O SC
-
— * — Average
— A — Control
-
-
-
3 1O 2Q 3O 4O SO 6O
Time (Days)
7Q SO
SO
2.5
2
1.5
1
0.5
O
Lake Hartwell Gas Generation Sampling at 25 °C
Control
O 10 20 30 40 50
Time (Days)
60
70
80
90
Lake Hartwell Gas Generation Sampling at 37 'C
O
O 10 20 30 40 50
Time (Days)
6O
60
90
Figure 3-2. Lake Hartwell Gas Generation at 10°C, 25°C, and 37°C
31
-------
Table 3-1. Gas Generation and Headspace Analysis of Microcosm Bottles Containing Eagle
Harbor Sediment
Sample Id
EH-10-1-1
EH-10-1-2
EHCT-10-1-1
EH-25-1-1
EH-25-1-2
EHCT-25-1-1
EH-37-1-1
EH-37-1-2
EHCT-37-1-1
EH-10-3-1
EH-10-3-2
EHCT-10-3-1
EH-25-3-1
EH-25-3-2
EHCT-25-3-1
EH-37-3-1
EH-37-3-2
EHCT-37-3-1
EH-10-14-1
EH-10-14-2
EHCT-10-14-1
EH-25-14-1
EH-25-14-2
EHCT-25-14-1
EH-37-14-1
EH-37-14-2
EHCT-37-14-1
EH-10-21-1
EH-10-21-2
EHCT-10-21-1
EH-25-21-1
EH-25-21-2
EHCT-25-21-1
EH-37-21-1
EH-37-21-2
EHCT-37-21-1
Number of
Bubbles
NA
NA
NA
NA
NA
48
52
40
74
NA
NA
37
13
19
52
45
65
73
NA
NA
NA
NA
NA
29
34
NA
56
NA
NA
10
NA
NA
15
42
40
63
Total Gas
Volume
(mL)
NA
NA
NA
NA
NA
2.00
2.16
1.67
3.08
NA
NA
1.54
0.54
0.79
2.16
1.87
2.71
3.04
NA
NA
NA
NA
NA
1.21
1.42
NA
2.33
NA
NA
0.42
NA
NA
0.62
1.75
1.67
2.62
Time (s)
NA
NA
NA
NA
NA
33.08
29.07
34.47
29.84
NA
NA
33.60
19.24
24.63
28.41
27.84
53.29
34.00
NA
NA
NA
NA
NA
49.29
35.47
NA
49.27
NA
NA
26.68
NA
NA
18.62
20.45
28.80
33.80
Incubation
Time (days)
1
3
14
21
Carbon
Dioxide
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.330
0.340
4.600
0.440
0.310
4.000
0.390
0.360
4.100
NA
NA
NA
NA
NA
NA
NA
NA
NA
Methane
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
O.200
0.200
O.200
0.200
O.200
0.200
O.200
O.200
O.200
NA
NA
NA
NA
NA
NA
NA
NA
NA
Oxygen
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.210
0.250
0.410
0.320
0.220
0.810
0.220
0.230
0.760
NA
NA
NA
NA
NA
NA
NA
NA
NA
32
-------
Table 3-1. Gas Generation and Headspace Analysis of Microcosm Bottles Containing Eagle
Harbor Sediment (Continued)
Sample Id
EH-10-30-1
EH-10-30-2
EHCT-10-30-1
EH-25-30-1
EH-25-30-2
EHCT-25-30-1
EH-37-30-1
EH-37-30-2
EHCT-37-30-1
EH-10-45-1
EH-10-45-2
EHCT-10-45-1
EH-25-45-1
EH-25-45-2
EHCT-25-45-1
EH-37-45-1
EH-37-45-2
EHCT-37-45-1
EH-10-60-1
EH-10-60-2
EHCT-10-60-1
EH-25-60-1
EH-25-60-2
EHCT-25-60-1
EH-37-60-1
EH-37-60-2
EHCT-37-60-1
EH-10-90-1
EH-10-90-2
EHCT-10-90-1
EH-25-90-1
EH-25-90-2
EHCT-25-90-1
EH-37-90-1
EH-37-90-2
EHCT-37-90-1
Number of
Bubbles
NA
NA
NA
NA
NA
NA
50
45
56
NA
NA
NA
NA
NA
8
56
49
60
NA
NA
NA
NA
NA
NA
67
41
62
NA
NA
NA
NA
NA
NA
24
32
65
Bubble
Volume
(ml)
NA
NA
NA
NA
NA
NA
2.08
1.87
2.33
NA
NA
NA
NA
NA
0.33
2.33
2.04
2.50
NA
NA
NA
NA
NA
NA
2.79
1.71
2.58
NA
NA
NA
NA
NA
NA
1.00
1.33
2.71
Time (s)
NA
NA
NA
NA
NA
NA
25.22
30.42
29.06
NA
NA
NA
NA
NA
20.69
29.47
26.86
31.25
NA
NA
NA
NA
NA
NA
36.45
26.40
34.02
NA
NA
NA
NA
NA
NA
23.20
28.29
38.09
Incubation
Time (days)
30
45
60
90
Carbon
Dioxide
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.660
0.860
3.200
0.410
0.440
3.900
1.800
1.600
NA
Methane
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
O.200
0.200
O.200
O.200
O.200
0.200
0.200
O.200
NA
Oxygen %
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.720
0.840
0.260
0.180
0.210
0.210
1.100
1.300
NA
33
-------
Table 3-2. Gas Generation and Headspace Analysis of Microcosm Bottles Containing Lake
Hartwell Sediment
Sample Id
LH-10-1-1
LH-10-1-2
LHCT-10-1-1
LH-25-1-1
LH-25-1-2
LHCT-25-1-1
LH-37-1-1
LH-37-1-2
LHCT-37-1-1
LH-10-3-1
LH-10-3-2
LHCT-10-3-1
LH-25-3-1
LH-25-3-2
LHCT-25-3-1
LH-37-3-1
LH-37-3-2
LHCT-37-3-1
LH-10-14-1
LH-10-14-2
LHCT-10-14-1
LH-25-14-1
LH-25-14-2
LHCT-25-14-1
LH-37-14-1
LH-37-14-2
LHCT-37-14-1
LH-10-21-1
LH-10-21-2
LHCT-10-21-1
LH-25-21-1
LH-25-21-2
LHCT-25-21-1
LH-37-21-1
LH-37-21-2
LHCT-37-21-1
Number of
Bubbles
NA
NA
NA
NA
NA
NA
34
39
40
NA
NA
NA
NA
NA
19
48
43
63
NA
NA
NA
NA
NA
NA
55
49
48
NA
NA
NA
NA
NA
NA
50
NA
65
Bubble
Volume
(ml)
NA
NA
NA
NA
NA
NA
1.42
1.62
1.67
NA
NA
NA
NA
NA
0.79
2.00
1.79
2.62
NA
NA
NA
NA
NA
NA
2.29
2.04
2.00
NA
NA
NA
NA
NA
NA
2.08
NA
2.71
Time (s)
NA
NA
NA
NA
NA
NA
18.44
33.21
24.80
NA
NA
NA
NA
NA
22.87
18.21
30.82
31.62
NA
NA
NA
NA
NA
NA
21.81
40.81
28.49
NA
NA
NA
NA
NA
NA
28.69
NA
26.44
Incubation
Time (days)
1
o
J
14
21
Carbon
Dioxide
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.200
O.200
1.800
O.200
0.200
2.900
0.350
0.350
3.700
NA
NA
NA
NA
NA
NA
NA
NA
NA
Methane
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.200
O.200
0.380
O.200
0.200
0.790
3.100
2.400
1.900
NA
NA
NA
NA
NA
NA
NA
NA
NA
Oxygen %
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.240
0.260
0.170
0.250
0.230
0.180
0.170
0.210
0.320
NA
NA
NA
NA
NA
NA
NA
NA
NA
34
-------
Table 3-2. Gas Generation and Headspace Analysis of Microcosm Bottles Containing Lake
Hartwell Sediment (Continued)
Sample Id
LH-10-30-1
LH-10-30-2
LHCT-10-30-1
LH-25-30-1
LH-25-30-2
LHCT-25-30-1
LH-37-30-1
LH-37-30-2
LHCT-37-30-1
LH-10-45-1
LH-10-45-2
LHCT-10-45-1
LH-25-45-1
LH-25-45-2
LHCT-25-45-1
LH-37-45-1
LH-37-45-2
LHCT-37-45-1
LH-10-60-1
LH-10-60-2
LHCT-10-60-1
LH-25-60-1
LH-25-60-2
LHCT-25-60-1
LH-37-60-1
LH-37-60-2
LHCT-37-60-1
LH-10-90-1
LH-10-90-2
LHCT-10-90-1
LH-25-90-1
LH-25-90-2
LHCT-25-90-1
LH-37-90-1
LH-37-90-2
LHCT-37-90-1
Number of
Bubbles
NA
NA
NA
9
NA
NA
65
66
50
NA
NA
NA
NA
NA
NA
60
57
72
NA
NA
NA
10
NA
NA
63
NA
NA
NA
NA
NA
NA
NA
NA
77
NA
65
Bubble
Volume
(ml)
NA
NA
NA
0.37
NA
NA
2.71
2.75
2.08
NA
NA
NA
NA
NA
NA
2.50
2.37
3.00
NA
NA
NA
0.42
NA
NA
2.62
NA
NA
NA
NA
NA
NA
NA
NA
3.21
NA
2.71
Time (s)
NA
NA
NA
13.49
NA
NA
23.64
27.42
23.80
NA
NA
NA
NA
NA
NA
22.45
18.63
31.61
NA
NA
NA
23.29
NA
NA
33.09
NA
NA
NA
NA
NA
NA
NA
NA
38.22
NA
39.49
Incubation
Time (days)
30
45
60
90
Carbon
Dioxide
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.230
0.490
2.700
0.380
0.390
2.800
3.200
4.900
NA
Methane
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
O.200
0.200
0.200
1.800
1.800
0.890
0.200
O.200
NA
Oxygen
%
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.300
0.530
0.250
0.310
0.340
0.240
6.700
3.900
NA
35
-------
Eagle Harbor Microcosm at 10 °C, 25 °C and 37 °C, sediment
80000
70000
60000
DSedimentlO °C
DSediment37 °C
D Sediment25 °C
• Nonincubated Sediment
tf.^.^ &' &
///>VVV ~ ,
#$£5$^^
v
_\'
OJ
ON
Eagle Harbor Microcosm at 10 °C, 25 °C and 37 °C, Water
5000000
4500000
4000000
3500000
3000000
2500000
|> 2000000
1500000
1000000
500000
T^_=
D Water 10°C D Water 25 °C D Water 37 °C
x^
^v^
^* ^* ^
y.-^> y.-^> «Xy _<£• v-J- v-J- v4 v4 -<& ,\< ,\< x< 3f? r _v*^ _v*^ _v*^ sir <& , K\* ,
-------
Lake Hartwell PCB concentration in the sediment of Day-90 microcosm bottles at 10 :C, 25 :'C and 37 °C
n Sediment 10 °C
n3ediment25°[;
n S ed i merit 37 "C
Nonincubated Sediment
•3 ^ i \ x _^ M s: s; s; VIM uuuuuuuuuuu uuuu******* ****^*»
?iJd^^^^^^^^1i^^^15^^^^^^^^^^^^^^^^^^^^^5^^?1
* •vfa**"*Jtata«**J*'».55B.*Sii*.!}||iaff5i^vWS£rf^w*&5 ^K^O^^X
« J ^^^^^^^^^^^^^^^^^^^S^ii
~ S ." ^™
r, T, x T, r, a
If V
•fi S
Lake Hartwell PCB concentration in the water of Day 90 microcosm bottles at 10 °C. 25 °C and 37 °C
dWateMCTC
•Water 25 "C
QWater 37 "C
Figure 3-4. Lake Hartwell Microcosm Sediment (upper) and Water (lower) after 90-days of Incubation at 10 °C, Room Temperature and 37 °C
37
-------
37 °C was -20 mV. It was anaerobic, but it was not as anaerobic as the other sample bottles containing
viable bacteria.
+800
ORP
(mV)
-250
Aerobic Respiration
Denitrification
Perchlorate Reduction
Sulfate Reduction
Reductive
Dechlorination
Methanogenesis
Figure 3-5. Relationship between the Redox Potential and Idealized Terminal
Electron Acceptor Process
The pH values of the microcosm bottles containing Lake Hartwell sediments after incubation varied
between 6.4 and 6.9. The ORP in the water after the incubation period was around -25 mV for the bottles
incubated at 10 °C and 25 °C. The ORP value was lower in the bottle that was incubated at 37 °C than
those at the other two temperatures. The measured pH value was also lower for the killed controls in
comparison with the other unkilled bottles, as observed for the bottles containing Eagle Harbor sediment.
Unlike the bottles containing Eagle Harbor sediment, the ORP of the killed control bottles containing
Lake Hartwell sediment maintained anaerobic conditions at all incubation temperatures.
38
-------
Table 3-3. pH and ORP of Lake Hartwell and Eagle Harbor Microcosm Bottles after 120-Days
Sample ID
EH- 10-1
EH- 10-2
EHCT-10-1
EH-25-1
EH-25-2
EHCT-25-1
EH-37-1
EH-37-2
EHCT-37-1
LH-10-1
LH-10-2
LHCT-10-1
LH-25-1
LH-25-2
LHCT-25-1
LH-37-1
LH-37-2
LHCT-37-1
Incubation
Temperature
(°C)
10
10
10
25
25
25
37
37
37
10
10
10
25
25
25
37
37
37
pH
7.54
7.37
6.91
7.55
8.34
7.28
7.53
7.40
7.12
6.88
6.40
6.13
6.88
6.92
6.27
6.82
6.81
6.29
ORP (mV)
-242.0
-221.0
139.5
-254.0
-256.4
132.1
-226.6
-209.9
-19.9
-26.3
-20.5
-10.0
-19.0
-24.1
-34.1
-111.2
-52.1
-60.9
3.2
Column Study
The results of the simulated gas ebullition columns for Eagle Harbor sediment and Lake Harbor
sediment are discussed in Sections 3.2.1 and 3.2.2, respectively. Columns packed with Eagle Harbor
sediments and Lake Hartwell sediments were evaluated for two gas flow conditions: a) at a flow rate of
6.5 mL/min, referred as "low" flow condition in this report, and b) at a flow rate of 18.7 mL/min, referred
as "high" flow condition in this report. The simulated gas sparging rate through the columns were
selected based on the literature data, the results of the microcosm tests conducted, and the laboratory
practicality. The simulated gas ebullition rates are discussed in Section 2.3.3.
For the column studies, there are four compartments - contaminated sediment and/or cap layer, water
column, gas layer, and PUF. Gas bubbles take contaminants from the sediment and water layers by
partitioning process, and release them as they transit the PUFs. The other major transport pathway is the
water entrainment in PUFs with the bubble. The CFL, gas bubbles brought sediment particles into the
water column upon leaving the sediment. The larger, heavier particles fell back to the sediment bed,
while the smaller, lighter particles remained suspended in the water column. The larger methane flux
generated stronger forces on the particles resulting in higher suspensions of solids in the water column.
These gas bubbles not only take up the contaminant from the pore water in the contaminated sediment but
also suspend fine particulates in the water column. Both contaminated sediment suspended particulates
and gas bubbles release contaminants (PCBs and PAHs) into the water column. The driving force for
mass transfer and organic desorption from gas and sediment particles is expected to be large at the
39
-------
beginning of the test as organic concentration in the water was relatively small. This results in an
increase in organic concentration in the water during the initial stages of the tests. With time, the driving
force decreases as the aqueous phase concentration increases. As the gas bubbles escapes the water
column they entrain a fraction of organic to the PUFs. At the beginning of the experiments, the
concentrations of organics in the PUFs increase slowly. Once the organic concentration in the water
column reaches equilibrium with the sediment particles, the bubbles transport organic from both sediment
porewater and water column.
Gas flux influences the mass distribution of PCBs and PAHs. It is obvious that the higher the flux of gas
passing through the column, the more organics carried into the PUFs. The total organic mass collected in
the PUFs are proportional to the gas flux.
3.2.1 Eagle Harbor Columns
Simulated gas ebullition at the low and high flow rates through the various columns packed
with Eagle Harbor sediments influenced the results of the various parameters.
• The impact on pH, redox potential, dissolved oxygen and turbidity of the overlayed water
by the gas ebullition of the columns are discussed in Section 3.2.1.1.
• The PAHs captured by the PUFs located at the outlet of the columns containing capped
sediment and uncapped sediment under low and high flow conditions were analyzed after
6-weeks and 19-weeks of continuous gas ebullition operation. In the case of PUFs
collected after 6-weeks of operation, the primary and secondary PUFs from each column
were analyzed for PAHs (or PCBs in the Lake Hartwell samples) individually. However,
at the end of the study (19-weeks), a composite sample containing both the primary and
secondary PUFs from the columns was analyzed. The results of PUF analysis are
discussed in Section 3.2.1.2.
• PAHs contain four-, five-, six- or seven-member rings, but those with five or six are most
common. PAHs with two rings are more soluble in water and more volatile than the
PAHs of three rings or more. As molecular weight increases, aqueous solubility and
vapor pressure decrease. The aqueous solubility decreases approximately one order of
magnitude for each additional ring. Because of these properties, PAHs in the
environment are found primarily in soil and sediment, as opposed to water or air. PAHs
are also often found in particles suspended in water and air. After 19-weeks of operation
of the columns, the concentrations of the PAHs were measured in sediment, water and
cap materials of each column. The profiles of PAHs in the sediment, water and cap are
compared at low and high flow conditions in Section 3.2.1.3.
• The mass of the total polycyclic aromatic hydrocarbon (tPAH) in initial sediment and
various other phases after 19-weeks of operation (sediment, cap, water, and PUF
materials) were compared by estimating the loss or recovery of tPAH in sediment, water,
PUF, or cap material (Section 3.2.1.4).
3.2.1.1 pH, Redox Potential, Dissolved Oxygen and Turbidity
At the end of gas sparging operation, the pH, ORP, DO and turbidity of the standing water from
each column were analyzed. Water was extracted by piercing the needle of a syringe at the side port of
the column. The measurements were taken immediately after extraction to minimize the interaction with
air.
40
-------
The Eagle Harbor water pH was -6.5, ORP ranged between -50 to -80 mV and the DO ranged
between 0.70 and 0.80 mg/L at the end of the gas ebullition (see Table 3-4). The negative value of ORP
suggests an anaerobic environment achieved by the column due to the sparging of a mixture of 60% CF^
and 40% CO2 gas through the columns. The difference in turbidity values indicated that the water in the
capped columns was clearer than the uncapped columns, even at high flow
3.2.1.2 PUF Analysis
Two PUFs were attached in series at the outlet of the Eagle Harbor columns. The second PUF
was included to ensure the capture of PAHs in case the first PUF had reached its saturation capacity with
respect to the COCs.
Eagle Harbor column #1 and #3 were sparged at low flow (6.5 mL/min) and were constructed
without cap materials to simulate uncapped sediment conditions. Eagle Harbor column #2 and #4 were
gas sparged at low flow and cap materials were applied at the top of the sediment layer to simulate capped
sediment. In Figure 3-6, the amounts of PAHs (3 8-priority PAHs in nanograms) for capped and
uncapped columns were plotted after 6-weeks and 19-weeks of gas sparging at low flow conditions. The
PUF data represented in Figure 3-6 was the sum from both PUFs in series at six weeks. The average
value of the duplicate samples is presented in this figure. The individual PUF data (ng/PUF) for
individual samples are listed in Appendix B. It was observed that the PUFs attached to the uncapped
columns captured more PAHs than the capped columns for both time intervals (i.e., 6-weeks and 19-
weeks of gas sparging). The cap materials attenuated PAH migration from the sediment phase to the
water and ultimately to the gas phase by sorbing these compounds. The lower molecular weight of the
PAHs captured by the PUFs at the outlet of the capped and uncapped columns was because of the
relatively higher water solubilities and vapor pressure of these compounds. However, the PUFs on the
Table 3-4. Eagle Harbor pH, ORP, DO and Turbidity of Column Water at the
End of Gas Ebullition
Column
No.
1
2
3
4
5
6
7
Column
Description
Low flow,
uncapped
Low Flow,
capped
Low flow,
uncapped
Low flow,
capped
High flow,
uncapped
High Flow,
capped
High Flow,
uncapped
pH
6.553
6.539
6.517
6.601
6.598
6.570
6.571
ORP
(mV)
-87.5
-71.0
-67.0
-81.0
-58.1
-52.1
-55.8
Dissolved
Oxygen
(mg/L)
0.64
0.71
0.73
0.75
0.83
0.80
0.80
Turbidity
(FTU)
73
18
57
25
187
16
72
uncapped columns were capturing higher molecular weight PAHs than the capped columns.
Phenanthrene (11,691 ng) was the highest molecular weight compound identified from the PUFs of the
41
-------
uncapped column. The most recovered compound from the PUFs was 1-methylnaphthalene, a lower
molecular weight PAH, for both the capped and uncapped low flow columns. These results showed that
cap materials can be effective in attenuating relatively higher molecular weight compounds (hydrophobic)
by providing additional sorptive surface than the native sediment.
Columns #5 and #7 containing Eagle Harbor sediment (uncapped) and Column #6 containing
Eagle Harbor sediment and cap material were sparged at a high gas flow (18.7 mL/min). The other
column containing Eagle Harbor sediment and cap material was not successful and data was not available.
The average amount of PAH (in nanograms) captured in the PUFs from the high flow, capped and
uncapped Eagle Harbor columns after 6 and 19 weeks are shown in Figure 3-7. At 6-weeks, the PUFs
connected to the capped columns collected less PAH than the uncapped columns. Furthermore, the PUFs
from the uncapped columns also collected higher molecular weight PAH compounds, such as fluorine,
than the capped column after 6-weeks.
After 19-weeks, the PUFs for the capped column sorbed more of the lower molecular weight,
such as 1-methylnaphthalene and Cl-naphthalenes compounds than the uncapped columns. However, the
uncapped PUFs consistently adhered to the higher molecular weight PAH compounds than the capped
column. For example, the average amount of pyrene extracted from the capped column was 4856 ng in
comparison to 1401 ng extracted from the uncapped columns.
3.2.1.3 PAH Concentration Profile in Eagle Harbor Sediment and Water
The average amount of 38-priority PAH compounds present in the initial Eagle Harbor
sediment was compared with the uncapped and capped columns after gas sparging for 19 weeks. Figure
3- 8 shows a comparison in the amount of PAHs at low flow conditions. Though the magnitude of the
amount of PAHs recovered from the sediments varied, the relative distribution of PAHs (profile) was
consistent for initial Eagle Harbor sediment and uncapped and capped sediments that were gas sparged
for 19 weeks. Similar trends were also observed for sediments that were gas sparged at high flow
conditions.
Similar plots of PAH profiles were prepared for the water at the low flow condition. Before the
initiation of gas sparging, the Eagle Harbor water had very low levels of PAHs. After sparging for 19-
weeks, portions of the PAH from the sediment were partitioned into the water phase. The relative
distributions of PAHs in the water from the uncapped and capped sediment columns were similar under
high gas flow conditions (Figure 3-9). The water from the capped sediment column had a tPAH of
128044 ng and the same from the uncapped sediment column was 145568 ng. The concentration of tPAH
in water from the uncapped sediment column was more than that of the capped sediment column.
3.2.1.4 Mass Balance of tPAH
The tPAH in the various phases was calculated by adding the various PAH compounds
recovered from sediment, cap (if present), water, and PUF at the end of the gas sparging. The amount not
recovered was considered to be lost. This un-recovered amount from various phases was also estimated
as percentage lost.
In Figure 3-10, the bars represent the amount of tPAH in various Eagle Harbor media at low flow
(6.5 mL/min) conditions at the beginning of gas sparging (i.e., t = 0) and after 19-weeks of gas sparging
through various columns. The tPAH captured from both 6- and 19-weeks PUFs were also included. The
uncapped sediment had more PAH losses, 55% from the initial sediment in comparison with the capped
sediment of 42%. The capped column recovered 3.9% of the lost PAH, which were seen in the water, cap
material and PUFs. The uncapped column recovered 2.8% of the PAH losses, which were accounted for
42
-------
from the water and PUF. The remaining PAH losses could not be accounted for because of the following
reasons:
• PAH losses from the sediment occurred as the columns were packed at the beginning of the
gas ebullition tests and as they were unpacked at the end of the tests.
• The binding of PAHs on the PUF Tenex material may not be strong enough to prevent any
volatilization losses. During the continuous operation of the columns under the ventilated
hood, a portion of PAH sorbed on the PUFs could have volatilized.
• The residence time of the PAH vapor through the PUF may not have been sufficient to
achieve high sorption capacity.
• A portion of the PAHs could have adhered to the stainless steel piping and the tygon tubing
at the top of the column before entering the PUF.
• The CO2 and CH4 gas could have stripped sorbed PAHs off the Tenex material as it
traversed through the PUFs.
The tPAH bar diagram was also prepared for the columns that were gas sparged at high flow
condition. As shown in Figure 3-11, the uncapped sediment had more PAH loses, 47.8% than the capped
sediment of 28.2%. The capped column recovered 11.5% of the PAH losses, which were captured in the
water, cap material and PUF. The uncapped column recovered 7.1% of the PAH loses, which were seen
in the water and PUF.
43
-------
3.2.1.5 PAH in Cap Material
Two inches of clean, coarse site-specific cap material (gravel) was at the top of the Eagle
Harbor sediment as described in the materials and methods and previous sections. After 19 weeks of gas
sparging the cap material was separated selectively from the column and was sent to Battelle's analytical
laboratory for PAH analysis. Figure 3-12 shows the cap performance to adhere/attenuate the PAH during
high and low gas flow conditions. It appeared from the graphs that the cap material was able to sorb more
(-2.9 times) PAH at the lower flow rate. The high flow cap material sorbed 360659 ng tPAH and the low
flow cap material sorbed 1030019.1 ng.
The relative distributions of PAHs sorbed by the cap material were the same under low and high
gas flow conditions. It is interesting to note that both the high and low cap material adsorbed
fluoranthene more than any other PAH.
3.2.2
Lake Hartwell Columns
Columns packed with Lake Hartwell sediment were evaluated for two gas flow conditions: a) at
a flow rate of 6.5 mL/min, referred as "low" flow condition in this report, and b) at a flow rate of 18.7
mL/min, referred as "high" flow condition in this report. Unlike Eagle Harbor columns, no cap material
was used for Lake Hartwell columns.
3.2.2.1 pH, Redox Potential, Dissolved Oxygen and Turbidity
The pH of the water in the Lake Hartwell columns ranged between 5.7 and 6.5 as seen in Table
3-5. The DO and ORP values indicated that the columns were anaerobic. Lake Hartwell sediment
consisted of clay rich material, most of which were in suspended conditions during the gas sparging
operation. The turbidity of the overlying water at the end of the gas sparging experiments measured a
value in excess of 460 FTU, which was the upper range of the HACK meter.
Table 3-5. Lake Hartwell Equilibrium Water pH, ORP, DO and Turbidity Measurements After
19-weeks Gas Sparging Operations
Column
No.
8
9
10
11
Column
Description
Low flow
High flow
Low flow,
PCB spiked
Low flow,
PCB spiked
pH
5.754
6.396
6.580
6.383
ORP
(mV)
41.8
-74.1
-138.1
-109.3
Dissolved
Oxygen
(mg/L)
0.35
0.06
0.06
0.05
Turbidity
(FTU)
>460
>460
>460
>460
3.2.2.2 PUF Analysis
Two PUFs were attached in series at the outlet of the Lake Hartwell columns. The second PUF
was included to ensure the capture of PCBs in the Lake Hartwell samples in case the first PUF had
reached its saturation capacity with respect to the COCs. After 6 and 19 weeks of gas sparging through
the Lake Hartwell columns, the PUFs at the outlet of the columns were sent to Battelle's analytical
44
-------
laboratory for PCB congener (118) analysis. The amounts of PCB congeners sorbed by the PUFs at low
gas sparging through the unspiked and spiked Lake Hartwell sediment are plotted in Figure 3-13. The
unspiked and spiked Lake Hartwell sediment had 161449 ng and 248953 ng of tPCB, respectively. The
PUFs adsorbed more PCBs from the spiked columns at both 6 and 19 weeks than the unspiked columns at
the same low flow rate. The PUFs that sorbed gas from week 6 through week 19 (i.e., a total duration of
13 weeks) not only sorbed more PCBs but also sorbed higher molecular weight PCBs in comparison with
the PUFs that were used for the first 6 weeks of gas sparging operation. At low gas flow rates, the PUFs
captured 1041 ng of tPCB for the columns with PCB spiked sediment and 164 ng for the columns with
unspiked Lake Hartwell sediment. After 19-weeks, the PUFs sorbed higher molecular weight PCBs, such
as C15(l 10) with the PCB spiked sediment. After 19-weeks, C13(19) was the highest molecular weight
congener sorbed by the PUFs attached to the column containing unspiked sediment.
At high gas sparging (Figure 3-14), the PUF adsorbed 1507 ng from columns with unspiked Lake
Hartwell sediment, in comparison to the low flow columns which adsorbed 164 ng of tPCBs. Higher gas
sparging also caused the release of PCBs with higher molecular weights. For example, the PUF detected
C16 (149) at 18.5 ml/min for unspiked Lake Hartwell sediment, whereas C13 (19) was the heaviest
compound detected at lower flow.
3.2.2.3 Mass Balance of tPAH
The amount of total PCB concentrations initially in the Lake Hartwell sediment
(unspiked and spiked), water and PUFs at the beginning of the gas sparging experiments and at the end of
19-weeks gas sparging are plotted in Figures 3-15 and 3-16. Figure 3-15 shows the mass balance of
PCBs in unspiked Lake Hartwell sediment at high and low gas flow conditions. Figure 3-16 shows the
same for the unspiked and spiked sediment at low gas flow conditions. The sediment in the columns
under low flow lost 18.3% tPCB in comparison with the original unspiked Lake Hartwell sediment over
the course of 19-weeks of gas sparging. The column water and PUF recovered 0.9% of the lost tPCB. At
high flow the unspiked sediment lost 35.0% tPCB. The water and PUF recovered 2.9% of the lost PCB.
The higher gas sparging flow rate resulted in more escape of PCBs. The chemical analysis of the spiked
sediment at the end of the study showed that on average it had a higher amount of tPCB (283582 ± 54819
ng) than the initial tPCB concentration in the sediment (248953 ng). This discrepancy might be due to the
non-homogeneity of the sediments in the columns. However, the water and the PUFs of the columns
containing Lake Hartwell sediment recovered 356 and 1041 ng of tPCB, respectively, forthe spiked
columns at low gas flow conditions.
A conceptual diagram depicting the sediment and contaminant movement in uncapped contaminated
sediment and capped contaminated sediment during gas ebullition is shown in Figure 3-17. Based on the
tests performed, the pathway of gas ebullition facilitated sediment contaminant transport through
sediment systems can be postulated. In case of an uncapped system, the simulated gas injected through
the bottom of the column take up contaminants from pore water in the contaminated sediment via
gas/water partitioning and would rise up into the water column. It was visually observed that the gas
bubbles bring the sediment particles as they move through the sediment-water interface. The heavier
particles sink back to the sediment after release and the lighter particles remain in the water column. In
case of Lake Hartwell, the clay particles from the sediment samples formed slurry (see Figure 2-8). The
contaminated particles in the slurry will desorb contaminants into the water phase. The gas bubbles also
facilitate the transport of contaminants transport from the porewater to the water column. These activities
increase the contaminant concentration in the water phase. As the gas traverse through the water column
and break the gas-water interface, contaminants are released into the gas/emply space of the column. In
the capped system, the gas injected through the contaminated sediment move through the cap material and
the gas bubbles release the contaminants into the porewater in the cap and water column. Though gas
movement has resulted mixing of the sediment and sand at the sediment-sand interface, the reduction in
45
-------
sediment suspension in the water column was observed. The cap layer could have acted as a filter
inhibiting sediment suspension, which reduced the source of contaminant into the water column.
46
-------
Eagle Harbor Low Flow (6.5 ml/min) PUF
•s.
OS
O
Q_
O)
D Capped 6-weeks
• Uncapped 6-weeks
D Capped 19-weeks
D Uncapped 19-weeks
S° cc cc"^
» S g? ® « ™
co~co'S.-o.-5-c"a-coi-i-.=:^!_3.c: £ £ E co co'crTfe S^£ mc/3^a5a5£a5mS££=c<£
-------
Eagle Harbor High Flow (18.7 ml/min) PUF
900000
800000
^ 700000
Q_
§ 600000
•t
"g 500000
3
" 400000
5. 300000
Q.
o) 200000
100000
n
O
• Capped 6-weeks
• Uncapped 6-weeks
D Capped 19-weeks
D Uncapped 19-weeks
04^5JOB-
-? «- oS
Siii^i^,f §§^2^
Ou" £
- -C _c <— J" n r» X^ >— C. X: W (/) m-^-C
;^^^o
CM-s
5==i3 ^.C
|S|I
Figure 3-7. PAHs Recovered from the Eagle Harbor Sediment (with and without cap) after High Flow Gas
Sparging for 6-weeks and 19-weeks
-------
1 8000000
1 6000000
1 4000000
x 1 2000000
< 1 0000000
ro 8000000
C 6000000
4000000
2000000
n
Initial Eagle Harbor Sediment
if
1-1 n
fln
lln-
a
5
n n.
D Initial Eagle Harbor Sediment
EC
n l~l fl „ !-!„„„
Sediment PAH (Uncapped)
<
ro
18000000
16000000
14000000
12000000
10000000
8000000
6000000
4000000
2000000
0
I
fi fi
.fl.pi, . .
U Sediment HAH (Uncapped)
T
t
1 8000000
1 6000000
1 4000000
.,. 1 2000000
< 1 0000000
en 8000000
C 6000000
4000000
2000000
n
PAH Sediment (Capped)
a H H R Pi _
T
[
T
Fi
„ _fl
a PAH Sediment (Capped)
S
I H
fin_ lln^.nn
Figure 3-8. PAH Profiles of Eagle Harbor Initial, Uncapped and Capped Sediment (low flow)
49
-------
60
50
40
30
20
10
Initial Eagle Harbor Water
n _ = „
n
D Initial Eagle Harbor Water
n
Eagle Harbor Water After 19 weeks (Uncapped)
<
Q_
10000
100
1
5
t
t
B
I
I
I
n
r
B
E
I
|
E
E
!
I
D Eagle Harbor Water After 1 9 weeks
(Uncapped)
5
G
5
i
1
1
I
I
I
i
1
1
i-
^>#>xS:>>< -yVc*' ^ ^ ^ A* <&• <&• <&• K? C^fyVTfTfT ^^veX*^^ ,o*wv«r
*^m$^
&* j&£&f ,x44/^ <^V .^^V
5r5r5r5r
c^VcT
< tr ^'tr ^-fcT .-i
K«9^
0NC?'C?
Eagle Harbor Water After 19 weeks (Capped)
10000
100
nn
fl
p.
-
-
-
-
D Eagle Harbor Water After 1 9 weeks
(Capped)
I
1
-
i-i
i-i
i-i
-
•V'^N'
Figure 3-9. PAH Profiles of Eagle Harbor Initial, Uncapped and Capped Water (high flow) tPAH
50
-------
tPAH at Low Flow (6.5 ml/min) of Eagle Harbor
100000000
10000000
1000000
x 100000
Q.
0)
= 10000
1000
100
10
1
92
-
-
-
-
991121
ng
212
1
J
D Sediment
• Water
D Total PUF
DCap Material
ng
41
55.4 % tPAH
losses in
sediment
3
42.0 % tPAh
losses in
sediment
71720ng 3J
I
AKI
45,
2.8% recovered
tPAH from water
and PUF
1283042)
ig
910b4Z
— I
12
]
ng
350
8044 m
3.9% recovered
tPAH from water,
PUF and cap
10
777 ng
]
-^-
3001 9 ng
I
1
t = 0
t = 19-weeks without cap
t = 19-weeks with cap
Figure 3-10. The Amount of tPAH in the Initial Sediment and Water and the Sediment, Water, Cap and PUF after
19-weeks for Low Flow Columns (6.5 ml/min)
-------
tPAH at High Flow (18.7 ml/min)
1000000000
100000000
10000000
1000000
100000
O)
= 10000
1000
100
10
92991121
-
ng
212 m
I
47.8 % tPAH loss
in sediment
485561 23 ng
T
D Sediment
• Water
DPIIF
DCap
3
_
1
(
\
3(
93087 i
T
1
M%
ecovered
PAH in the
water and
3UF
28.2 % tPAH
loss in
sediment
66'
)77520 ng
g
^84385 ng
j
2e
4614 n
11. 5% recovered
tPAH in the water,
PDF and cap
17601 7 ng
]
J60659
ng
t = 0
t = 19-weeks without cap
t = 19-weeks with cap
Figure 3-11. The Amount of PAH in the Initial Sediment and Water and the Sediment, Water, Cap and PUF After
19-weeks for High Flow Columns (18.7 ml/min)
-------
PAH in Cap Material week 19 (Low Flow)
<
Q.
O
c
600000
500000
400000
300000
200000
100000
0
D PAH in Cap Material
I
m .,
1
LljL-JLjLm = K _ =
<
Q.
ra
c
PAH from Cap Material week 19 (High Flow)
150000
125000
100000
75000
50000
25000
1
•
|n PAH from Cap Material (19-weeks)|
•
n n
1 1 n _ 1 1 1 n nrinn
<5TO?VJ^x&i^&&^
>°
A**
Figure 3-12. Eagle Harbor Cap Material at Low Flow 6.5 ml/min (upper graph) and High Flow
53
-------
Lake Hartwell PCB captured in PUF for Low Flow (6.5 ml/min)
400
350
• Low Flow Unspiked 6-week
• Low Flow Unspiked 19-weeks
D Low Flow Spiked 6-weeks
D Low Flow Spiked 19 weeks
Figure 3-13. Comparison of PCBs at Low Flow (6.5 ml/min) for Spiked and Unspiked Lake Hartwell Sediment
-------
400
Comparrison of Lake Hartwell PCBs captured in PDF for Low Flow (6.5 ml/min) and High Flow
(18.7 ml/min) for unspiked sediment
• Low Flow Unspiked 6-week
• Low Flow Unspiked 19-weeks
DHigh Flow Unspiked 6-weeks
DHigh Flow Unspiked after 19-weeks
Figure 3-14. Comparison of PCBs at Low Flow (6.5 ml/min) and High Flow (18.7 ml/min) for Unspiked Lake Hartwell Sediment
-------
1000000
100000
10000
CO
o
S: 1000
D)
100
10
Lake Hartwell tPCB in sediment, water and PDF versus time at low (6.5 ml/min) and high flow
(18.7ml/min)
161449 ng
DUnspiked Sediment
• Water
DTotal PUF
|18.3%tPCB loses from sediment
131831 ng
2 ng
0.9% tPCB
recovery from
water and PUF
164 ng
101 ng
35.0% tPCB loses from sediment
104950 ng
2.9% tPCB
recovery from
water and PUF
1507 ng
107 ng
t = 0
t = 19 weeks Low Flow
t = 19 weeks High Flow
Figure 3-15. Lake Hartwell tPCB Comparison Initially and After 19-weeks for Unspiked Sediment at Low Flow (6.5 ml/min) and High
Flow (18.7 ml/min)
-------
1000000
Lake Hartwell tPCB of spiked and unspiked in sediment, water and PDF versus time at low
flow (6.5 ml/min)
100000
10000
00
o
£ 1000
100
10
248953
161449
D Spiked Sediment
D Unspiked Sediment
• Water
DPIIF
283582
-i—
1041
356
J
18.3% tPCB
loses from
131831
0.9% tPCB
recovery from
water and PDF
164
101
t = 0
t = 19 weeks spiked sediment
t = 19 weeks unspiked sediment
Figure 3-16. Lake Hartwell tPCB Comparison Initially and After 19-weeks for Spiked and Unspiked Sediment at Low Flow (6.5 ml/min)
-------
00
L ..
Release to Atmosphere
ft
Collection on Polyurethane Foam
1
PUF
1
A
Emission
I Gas Phase]
O
Contaminant exchange with
water and suspended solids*
o
O O
Contaminant
"^exchange with
water and qas bubble
Gas Entrance
Desorption
O
O—»> Contaminant uptake
O from porewater
Contaminated Sediment
and/or Cap Layers
V
Sorption
o
Figure 3-17. Conceptual Diagram of Gas Ebullition and Contaminant Migration through the Sediment-Water-Gas phases
(Chattopadhyay, 2006)
-------
Section 4.0 SUMMARY
The results of the microcosm experiments are summarized below.
• The pH of water in the serum bottles containing Eagle Harbor sediment varied between 7.3 and
8.3 and ORP of the same varied between -210 to -240 mV after 19 weeks of incubation. The
killed control bottles had an oxidizing environment (ORP = 130 mV) more than the other bottles.
The pH of the water in the serum bottles containing Lake Hartwell sediment varied between 6.4
and 6.9, and the ORP of the same varied between -25 mV and -110 mV. The killed control
bottles maintained the reducing environment (negative ORP value) like the sample serum bottles
containing Lake Hartwell sediment.
• Higher percentages of methane and carbon dioxide were present in the headspace of the Lake
Hartwell serum bottles than the Eagle Harbor samples at 37 °C. No detectable level of gas
(methane or carbon dioxide) was measured at lower temperatures (10 °C and 25 °C) for either
sediments (Eagle Harbor or Lake Hartwell). Detectable amounts of gases were measured at all
time intervals for both Eagle Harbor and Lake Hartwell sediments at 37 °C.
• The serum bottles containing sediment and water from Eagle Harbor and Lake Hartwell were
incubated at 10°C, 25 °C (room temperature) and 37°C. These serum bottles were analyzed for
38-priority PAHs (Eagle Harbor samples) or PCBs (Lake Hartwell samples) after 90-days of
incubation. Higher concentrations of PAHs (ng/g) were observed in the Eagle Harbor sediment
as the temperature increased from 10 °C to 37 °C. This type of trend was observed from low and
high molecular weight compounds of PAHs. An inverse relationship was observed in the case of
the incubated Eagle Harbor water. The concentration of PAH (ng/L) in the water decreased from
low temperature (10 °C) to higher temperature 37°C.
• The concentrations of PCBs (ng/g) in the serum bottles containing Lake Hartwell sediment with
an incubation temperature of 10 °C were higher than those bottles incubated at 25 °C and 37 °C.
However, the PCB concentrations in water (ng/L) increased as the incubation temperature
increased from 10 °C to 37 °C. However, this trend was reversed for the higher molecular weight
PCBs in sediment, where the concentration decreased from low to high temperature. The PCBs
in the Lake Hartwell sediment partitioned into the water phase more strongly at a higher
temperature than lower temperature.
The results of the simulated gas ebullition column experiments are summarized below.
Eagle Harbor
• The total amount (combination of 6 and 19 weeks) of tPAH captured by the PUFs connected to
the uncapped Eagle Harbor columns at a low gas flow rate (6.5 mL/min) was 1283042 ng, which
was significantly more than the capped column (350,077 ng). The uncapped PUFs also recovered
higher molecular weight PAHs, which were not detected in the capped PUF. The uncapped Eagle
Harbor sediment lost 55.4% of the tPAH after 19-weeks of gas sparging with respect to the tPAH
concentration in the sediment inside the column prior to the gas sparging. The sediment from the
column containing both sediment and cap material lost 42.0% tPAH. The water and PUFs
recovered 2.8% of the tPAH losses from the sediment for the uncapped column. The water, cap
material and PUF recovered 3.9% of the lost tPAH from the capped column.
59
-------
• At high gas flow rates (18.7 mL/min), the PUFs captured 3077520 ng tPAH for the uncapped
sediment column while the PUFs from the capped column captured 2576017 ng tPAH. After 19-
weeks of gas sparging operation, the PUFs for the capped column sorbed lower molecular weight
PAH compounds, such as 1-methylnaphthalene and Cl-naphthalenes, than the uncapped column.
However, the PUFs from the uncapped column sorbed higher molecular weight PAH compounds
than the capped column. The Eagle Harbor sediment without a cap lost 47.8% of the tPAH after
19-weeks of gas sparging with respect to the tPAH concentration in the sediment inside the
column prior to the gas sparging at a high flow rate. The sediment from the column containing
both sediment and cap lost 28.2% tPAH. The water and PUF recovered 7.1% of the tPAH losses
from the sediment for the uncapped column. The water, cap material and PUF recovered 11.5%
of the lost tPAH from the capped column.
• The possible reasons for the loss of the tPAH losses from the Eagle Harbor sediment could be:
n PAH losses from the sediment occurred as the columns were packed at the beginning of the
gas ebullition tests and as they were unpacked at the end of the tests.
O The binding of PAHs on the PUF Tenex material may not be strong enough to prevent any
volatilization losses. During the continuous operation of the columns under the ventilated
hood, a portion of the PAH that sorbed on the PUFs could have volatilized.
n The residence time of the PAH vapor through the PUF may not have been sufficient to
achieve high sorption capacity.
O A portion of the PAHs could have adhered to the stainless steel piping and the tygon tubing at
the top of the column before entering the PUF.
O The carbon dioxide and methane gas could have stripped sorbed PAHs onto the Tenex
material as it traversed through the PUFs.
• The Eagle Harbor sediment (initial, uncapped and capped) and water (initial, uncapped and
capped) have a similar distribution of PAH compounds. Though the magnitudes of the PAH
concentrations were different, the pattern was consistent.
• The cap material sorbed more PAH at the lower gas ebullition rate. At high flow (18.7 ml/min),
the cap material sorbed 360659 ng tPAH and at low flow (6.5 mL/min), the cap material sorbed
1030019 ng (i.e., 2.9 times more sorption).
Lake Hartwell
• The PUFs at the outlet of the columns containing Lake Hartwell spiked and unspiked sediment
captured 1041 ng and 164 ng of tPCB, respectively, at low gas flow conditions. The PUFs were
also captured at higher molecular weight PCBs (such as C15(l 10)) from the PCB spiked
sediment.
• During high gas sparging, the PUFs sorbed 1507 ng from columns that were packed with
unspiked Lake Hartwell sediment in comparison to the low flow columns which sorbed 164 ng.
The transfer of PCBs from the sediment to the water column and thereafter to the air appeared to
be more dependent on the sparging flow rate than the concentration of PCB in the sediment.
Higher concentrations of PCBs (hydrophobic) could be sorbed in the sediment with a low risk of
escape as long as the gas ebullition rate was low. Higher gas sparging also resulted in the release
of higher molecular weight PCBs. For example, the PUFs detected C16 (149) at 18.5 mL/min for
60
-------
unspiked Lake Hartwell sediment, whereas C13 (19) was the highest molecular weight compound
detected at low flow.
The sediment in the columns under low gas flow conditions lost 18.3% tPCB with respect to the
tPCBs concentration in the unspiked Lake Hartwell sediment contained inside the column prior to
the gas sparging at a high flow rate. The water and PUF recovered 0.9% of the lost tPCB. At
high gas flow condition, the unspiked sediment lost 35.0% tPCB. The water and PUF recovered
2.9% of the lost PCB. The higher gas sparging flow rate resulted in higher transfer of PCBs from
the sediment surfaces.
61
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Section 5.0 REFERENCES
Bastviken, D., J. Cole, M. Pace, and L. Tranvik. 2004. "Methane Emissions from Lakes: Dependence of
Lake Characteristics, Two Regional Assessments, and a Global Estimate." Global Biogeochemical
Cycles 18: 1-12.
Chattopadhyay, S. 2006. Management of Mercury Pollution in Sediments: Research, Observations, and
Lessons Learned. U.S. Environmental Protection Agency, National Risk Management Research
Laboratory, Cincinnati, Ohio.
Fendinger, N.J., D.D. Adams, and D.E. Glotfelty. 1992. "The Role of Gas Ebullition in the Transport of
Organic Contaminants from Sediments." The Science of the Total Environment 112:189-201.
Hughes, J.B., K.T. Valsaraj, and C.S. Willson. 2004. In-Situ Containment and Treatment: Engineering
Cap Integrity and Reactivity. Available at: http://www.hsrc-ssw.org/hughes04.pdf
Ostrovsky, I. 2003. "Methane Bubbles in Lake Kinneret: Quantification and Temporal and Spatial
Heterogeneity." Limnol. Oceanogr. 48(3): 1030-1036.
Stumm, W. and Morgan, J.J. 1996. "Aquatic Chemistry, Chemical Equilibria and Rates in Natural
Waters." 3rd ed. John Wiley & Sons, Inc., New York, 1022p.
Thibodeaux, L.J., Valsaraj, K.T., Rieble, D.D. 2001. "Bioturbation driven transport of hydrophobic
organic contaminants from sediment." Environ. Eng. Sci. 18(4):215-223.
United States Environmental Protection Agency. 1996. Method 8270C: Determination of Semivolatile
Organic Compounds by Gas Chromatography/ Mass Spectrometry. EPA SW846. EPA Office of
Solid Waste and Emergency Response. Washington D.C.
United States Environmental Protection Agency. 1999. Chlorinated Biphenyl Congeners in Water, Soil,
Sediment, and Tissue by HRGC/HRMS, Method 1668, Revision A, Office of Water, U.S.
Environmental Protection Agency, Washington, DC.
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