PDA U.S. Environmental Washington, DC
&* ** Protection Agency EPA-SAB-EPEC-90-018
Report of The
Sediment Criteria
Subcommittee of The
Ecological Processes and
Effects Committee
Evaluation of The
Sediment Classification
Methods Compendium
A SCIENCE ADVISORY BOARD REPORT July, 1990
' CD
Headguarters Library
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D C 20460
Office or
July 11, 1990 EPA-SAB-EPEC-9rO-0A18N1STB*T°"
o , i -
The Honorable William Reilly " -
Administrator ,
U.S. Environmental Protection Agency ;
401 M. Street, S.W. . •
Washington, D.C. 20460
Dear Mr. Reilly:
The Sediment Criteria Subcommittee of the Science Advisory
Board (SAB) has completed its review of the Sediment Methods
Classification Compendium that was developed by the Office of Water
Regulations and Standards in the Office of Water and EPA's Sediment
Oversight Technical Committee. This guidance describes the
strengths, limitations, and applications of ten methods that can
be used to evaluate sediment quality. The guidance is intended for
use by managers and decision makers and it does not make specific
recommendations for applying these approaches for particular sites
or types of problems.
This review is the third to be completed in a series of SAB
reviews of sediment quality.methodology. Previously the Sediment
Criteria Subcouinii'uaa presented recommendations and conclusions to
EPA concerned with the Apparent Effects Threshold and Equilibrium
Partitioning approaches. These approaches are also included in
the compendium.
The Subcommittee met ones, on December 11-12, 1989, to review
and evaluate the compendium. The Subcommittee was asked to address
the following chargs:
1) Identify any serious flaws in the methodologies, expand
the list of advantages and limitations, and evaluate whether
each methodology is portrayed appropriately as narrow or broad
use.
2) Recommend alternative sediment classification methods.
and research areas.
3) Assess the robustness of each approach.
The Subcommittee believes that all of the methods in the
Compendium and the advice for their application have scientific
merit except as noted below. The subcommittee did not identify any
additional methods for inclusion'in the Compendium, however, it
recommends that whenever possible, a suite of methods should be
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recommends that whenever possible, a suite of methods should be
used to develop sediment quality values.
Overall, the Subcommittee believes that the Compendium will
be most useful if it is periodically updated and if the Agency
conducts research to address the limitations associated with
particular approaches. In addition, the introduction should
include a summary of references and advice to managers for sample
collection and handling, quality assurance/quality control, tiered
approaches for mixtures of chemicals, and data analysis. The
Subcommittee suggests that EPA add-a table to the Compendium that
summarizes information on the status and relative, costs of each
method. •
i
The Subcommittee recommends that EPA conduct further research
to address the limitations of the methods. EPA should develop
.sediment toxicity test methods . for more freshwater and marine
species; develop protocols for handling and collecting samples, for
sample storage, and basic quality assurance procedures; evaluate
applicability of the wastewater procedures for Toxicity
Identification Evaluation to sediments; and investigate the
mechanism and the role of kinetics in the partitioning of
substances on sediments. Additional methods are also needed to
assess chronic and sublethal endpoints. The Subcommittee also
recommends that the EPA consider further development of the Tissue
Residue approach which has the potential to be used as a major tool
in assessing sediment quality. The method could have even wider
applicability if research could define the mechanisms of
partitioning in the "real world" and the relationship between
tissue residues and toxicity.
The Subcommittee appreciates the opportunity to conduct this
scientific review. We look forward to receiving the Agency
response to the scientific advice transmitted in the attached
report.
Sincerely,
Dr.Raymond
Executive Committee
Science Advisory Board
man
Kenneth Dickson, Chairman
Ecological Processes and
Effect Committee
Dr. Robert Huggett^Chairman
Sediment Criteria Subcommittee
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U.S. ENVIRONMENTAL PROTECTION AGENCY
NOTICE
This report has been written as a part of the activities of
the Science Advisory Board, a public advisory group providing
extramural scientific information and advice to the Administrator
and other officials of the Environmental Protection Agency. The
Board is structured to provide a balanced expert assessment of
scientific matters related to. problems facing the Agency. This
report has not been reviewed for approval by the Agency; and,
hence, the contents of this report do not necessarily represent
the views and policies of the Environmental Protection Agency or
other agencies in Federal government. Mention of trade names or
ccauaeroial products does not constitute a recommendation for use.
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.U.S. ENVIRONMENTAL PROTECTION AGENCY
SCIENCE ADVISORY BOARD
ENVIRONMENTAL EFFECTS, TRANSPORT AND FATE COMMITTEE
SEDIMENT CRITERIA SUBCOMMITTEE
ROSTER
CHAIRMAN
Dr. Robert Huggett
Virginia Institute of Marine Science
School of Marine Sciences
College of William and Mary
Gloucester Point, Virginia 23062
VICE CHAIRMAN
Dr. Rolf Hartung
University of Michigan
3125 Fernwood Avenue
Ann Arbor, Michigan 48108-1955
MEMBERS •
Dr. William J. Adams
Monsanto Company (U4G)
800 N. Lindbergh Blvd.
St. Louis, Missouri 63167
Dr. Kenneth L. Dickson
University of North Texas
Institute of Applied Sciences
P.O. Box 13078
Denton, Texas 76203
Dr. Benjamin C. Dysart III ,
Environmental and Water
Resources Engineering
401 Rhodes Engineering Research Center
clemson University
Clemson, South Carolina 29634-0919
Dr. Eugene Kenaga
Consultant (Ret./Dow)
1584 E. Pine River Road
Midland, Michigan 48640
ii
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Dr. Frederick K. Pfaender
Department of Environmental Sciences
and Engineering
University of North Carolina
Chapel Hill, North Carolina 27599-7400
Dr. Y. Peter Sheng
Professor, Department of Coastal.and
Oceanographic Engineering
336 Weil Hall
University of Florida
Gainesville, Florida 32611
SUBCOMMITTEE LIAISONS
Dr. Robert M. Engler
(CEWESEP-D)
Waterways Experiment Station
U.S.' Army Corps of Engineers
P.O. BOX 631
Vicksburg, Mississippi 39180
Dr. Chris ingersoll
National Fisheries Contaminant
Research Center
U.S. Fish and Wildlife Service
Route 2 '. • ,
Columbia, Missouri 65201
Dr. H. Suzanne Bolton
NOAA-DOC / •
Office of Legislative Affairs
(LAX-2)
Herbert C. Hoover Building
Room 5222 .
Washington, O.c. 20230
SCIENCE ADVISORY BOARD STAFF
Dr. Edward S. Bender
Biologist & Executive Secretary
U.S. Environmental Protection Agency
Science Advisory Board
401 M Street, S.W.
Washington, D.C. 20460
Ms. Frances Dolby i
Staff Secretary
Science Advisory Board
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TABLE OF CONTENTS '
1.0 Executive. Summary.
.
2.0 Introduction ........... ........ 3
2.1 Request for Science Advisory Board Review . . 3
2.1.1 Charge to the Subcommittee ...... 3
2.2 Subcommittee Review Procedures .....<.. 4
2.3 Expected Future Activities .' ........ 4
3.0 Bulk Sediment Toxicity Test Approach ..... . . 4
3.1 General description of the approach . ... • *
3.2 Advantages of the approach ....... ... 5
3.3 Limitations of the approach ......... 5
, 3.4 Robustness of the approach .......... 5
3.5 Research recommendations ........ .... 5
4.0 Spiked Sediment Toxicity Test Approach ....... 6
4 . 1 General description of the approach ..... 6
4.2 Advantages of the approach .... ...... 6
4.3 Limitations of the approach ........ . 6
4.4 Robustness of the approach ..... ..... 7
4.5 Recommendations ... ............ 7
5.0 Toxicity Identification Evaluations:
Interstitial Water Toxicity Approach ....... 7
5.1 "en^ra* description of the approach ..... 7
5.2 Advantages of the approach . . . ...... . s
5.3 Limitations of the approach ......... . 8
'5.4 Robustness of the approach .......... 9
5.5 Recommendations ............... 10
6.0 Equilibrium Partitioning Approach ......... 11
6.1 General description of the approach ..... 11
6.2 Advantages of the approach . ....... . . 11
6.3 Limitations of the approach ......... 11
6.4 Robustness of the approach ..... ..... 12
6.5 Recommendations ............... 12
7 . 0 Tissue Residue Approach ...... ..... ... 12
7.1 General description of the approach ..... 12
7.2 Advantages of the approach ........ • • 13
7.3 Limitations of approach .... ....... 13
7.4 Robustness of the approach ........... 14
7.5 *»non»mendation . ......... ...... 14
8.0 Freshwater Benthic Macro invertebrate Community
Structure and Function' Approach ...... ..... 14
8.1 General description of approach ....... 14
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3.2 Advantages of the approach ...'.: 15
8.3 Limitations of the approach . 16
8.4 Robustness of the approach 16
8.5 Recommendations 17
9.0 'Marine Benthic Community Structure Assessment ... 17
9.1 General Description of the approach ..... 17
9.2 Advantages of the approach .......... 17
9.3 Limitations of the approach ......... 18
9.4 Robustness of the approach . . 13
9.5 Recommendations ....... is
10.0 Sediment Quality Triad Approach . 18
10.1 General description of the approach is
10.2 Advantages of the approach ,. . . 19
10.3 Limitations of the approach . . 19
10.4 Robustness of the approach 19
10.5 Recommendations 19
11.0 Apparent Effects Threshold Approach 20
11.1 General description of the approach . . .... 20
11.2 Strengths of the approach 20
11.3 Limita-tions of the approach .'. 21
11.4 Robustness of the approach . < 21
11.5 Recommendations 21
12.0 International Joint Commission Sediment Strategy . 21.
12.1 General description of the approach 21
12.2 Strengths of the approach . . . . 22
12.3 Limitations of the approach 22
12.4 Rnb-j-tness of the approach 22
12.5 Recommendations .... ...... 23
13.0 Summary of Findings and Recommendations ...... 23
14.0 Literature cited 25
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l.o EXECUTIVE strmqvpy
The Sediment Methods Classification Compendium was developed
by the Office of Water Regulations and Standards to serve as a
reference for methods that can be used to assess the quality of
chemically contaminated sediments. The compendium describes each
method, associated strengths and limitations and existing
applications. The guidance is intended for general use by
managers and decision makers and it is does not make specific
recommendations for particular sites or problems.
Overall, the Subcommittee believes that the Compendium will
be useful if it is periodically updated and if the Agency
conducts research to address some of the limitations associated
with particular approaches. In addition, the introduction should
be expanded to include a discussion of references and advice for
sample collection and handling, quality assurance/quality
control, tiered approaches for mixtures of chemicals, and data
analysis.
The Subcommittee recommends that EPA conduct research to
expand the battery of freshwater and marine species that can be
.tested in the Bulk Sediment Toxicity Test Approach. For all
approaches, protocols should be developed for handling and
collecting samples, for sample storage, and basic quality
assurance procedures. This should be added as introductory
material to the compendium. Additional methods are needed to
assess other endpoints, such as chronic toxicity and
teratogenicity.
The Subcommittee recommends that EPA investigate the effects
of "aging" of spiked sediments and examine the extent to which
the Spiked Sediment Toxicity Approach can be used to estimate the
effects from mixtures.
The Subcommittee recommends that EPA expand the discussion
of the Interstitial Water Toxicity Approach to emphasize its
strengths for identifying sediment toxicity. Additional research
should be performed to evaluate the applicability of the TIE
procedures to sediments.
The Subcommittee reiterates its recommendations from an
earlier review of the Equilibrium Partitioning approach (EPA-SAB-
EPEC-90-006, February, 1990). The compendium should caution
users of this method to express the uncertainties in the
assumptions and to avoid cumulative errors in the calculation of
the partition values. The availability of compounds associated
with sediment EUJ b* controlled by kinetics rather than by
partitioning. The possible influence of kinetics should be
considered when the equilibrium partitioning approach is used to
establish sediment quality values. '
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The 'Subcommittee recommends that the EPA consider further
development of the Tissue Residue approach which has the .
potential to be used as a major tool in assessing sediment
quality. The method could have even wider applicability if
research could define the mechanisms of partitioning in the "real
world" and the relationship between tissue residues and toxicity.
The Subcommittee believes that the Freshwater and Marine
Benthic Macroinvertebrate Community approaches are useful for
screening sediments for potential contamination and for source
identification. Discussion should be added to the compendium to
help users identify reference sites for both approaches.
The Subcommittee recommends that the Sediment Triad and the
Apparent Effects Threshold (AET) approaches be cross- referenced.
The AET approach should provide a full and balanced discussion of
its strengths and weaknesses. Additional comments were provided
on the AET approach in a separate report (EPA-SAB-EEFTC-89-027,
August, 1989).
The Subcommittee recommends that EPA highlight the
International Joint Commission Sediment Strategy for its
conceptual strength in addressing the potential effects of
contaminants in sediment.
The Subcommittee did not identify any additional sediment
classification methods for inclusion in the compendium.
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2.0
The Compendium is essentially a synopsis of methods that can
be used to assess chemically contaminated sediments. It contains
a brief description of each method, associated advantages and
limitations, and existing applications. It is intended to serve
as a common frame of reference to assist users in assessing
contaminated sediments and determining whether sediment
contamination exists to a degree that warrants an evaluation of
needs for further action. It should be noted that these methods
are not at an equal stage of development, and certain ones (or
combinations) are more appropriate for specific management
actions than are others. The Compendium is not meant to provide
guidance on which method(s) to apply for specific situations, nor
how they can be used together as. part of a decision-making
framework.
2 . 1 Request for Science Advisory Board Review
At the request of the Office of Water/ the Science
Advisory Board (SAB) agreed to conduct a scientific review
of the Sediment Classification Methods Compendium, with the
approval of the Board's Executive Committee, the SAB's Ecological
Processes and Effects Committee authorized the formation of a
Subcommittee to perform a series of tasks related to the
technical aspects of sediment quality assessment and criteria
development.
a. 1.1 Charge to the Subcommittee
This review is the third to be completed in a series of SAB
reviews related to sediment quality values., The first and
second reports of the Subcommittee presented recommendations
and conclusions concerned with the Apparent Effects
Threshold (AŁT) Approach and the Equilibrium Partitioning (EqP)
Approach respectively.
The Office of Hater Regulations and Standards and the Office
of Marine and Estuarine Programs requested tliat the Subcommittee
review the Compendium as an encyclopedia of sediment
classification methods, rather than a "how to" manual on
implementing the methods or as a technical defense of each
method. Specifically, the charge accepted by the Subcommittee
was to:
1) Identify any serious flaws in the methodologies, expand
the list of advantages and limitations, and evaluate whether
each methodology is portrayed appropriately as narrow or
broad use.
2) Recommend alternative sediment classification methods.
3
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and research areas.
3) Assess the robustness of each approach,
2.2
The Sediment criteria Subcommittee met on December 11 and
12, 1989, in Washington, DC,,to begin its review of the
Sediment Classification Methods Compendium. Following the
meeting, members of the Subcommittee submitted evaluations of
individual chapters of the- compendium. Each evaluation included
an assessment of the charge. This report contains the advantages
and limitations that the Subcommittee believes were most
important for each method, including some of those listed in the
Compendium. The Subcommittee did not identify any alternative
sediment classification methods for inclusion in the compendium
at this time. . ' '
2.3 Expected Future Activities
Other sediment quality assessment methods, including methods
for assessing metal availability, are expected to be developed
and refined by EPA/OW's Contaminated Sediment Technical
Committee. Periodically, revised and new methods will be
submitted to the Sediment Criteria Subcommittee for review, prior
to the final draft of the guidance.
/
During the course of these critical evaluation processes, it
is likely that areas for additional or .future research will be
targeted. To facilitate the incorporation of these recommenda-
tions into EPA research planning, the Subcommittee may conduct a
review of the Office of Research and Development's proposed Sedi-
ment Initiative. The time sequence of these proposed events is
contingent on the completion by Agency staff.
3.0 BULK SBDIMBMT TOMCITY TEST APPROACH
3.1 General description of the approach
The Bulk sediaent Toxicity Test Approach consists of
exposing test organism(s) to sediments. At the end of a
specified exposure period, the response(s) of the test organisms
is examined using several biological endpoints. Endpoints
commonly used include mortality, growth, reproduction,
cytotoxicity, alterations in development, and behavior. Results
are compared to control and reference sediments to estimate
sediment toxicity. Test organisms routinely used in the Bulk
Sediment Toxicity Testing include amphipods, midges, polychaetes,
and oligochaetes. .
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3-2 Advantages of tha approach
The major strength of the Bulk Sediment Toxicity Test'
Approach is that it provides a direct measure of toxicity of the
sediment assayed. It measures the combined toxicities of all
chemical contaminants that are available. By utilizing test
organisms that are in intimate contact with the sediments, the
test simulates exposure regimes experienced by sediment dwelling-
organisms. There exists a long history of using the method for
assessing the spatial distribution of sediment contaminants and
in conducting trends analyses.
The available bulk sediment toxicity methods are relatively
simple to perform and do not require expensive equipment nor
highly trained personnel. They are, however, relatively
expensive, because they are labor intensive. ,
3.3 Limitations of the approach
The Bulk Sediment Toxicity Test Approach cannot be used by
itself to generate sediment quality values since the approach may
not always provide information on the causative toxic agent (s) .
However, the method has been integrated into- the Sediment Triad
and the Apparent Effects Threshold (AET) approaches which have
been used, to develop numeric estimates of sediment quality.
While not a conceptual weakness, the Bulk Sediment Toxicity
Test Approach is limited by the relatively fey species which are
available for testing. Control or reference sediments are
clearly cr it ire- 11;; ->ortant to the quality of the toxicity
evaluation, but little information is available on how to choose
them and on what characteristics are important. In addition, the
collection, preparation, and storage of the sediments may
influence the outcome of the test by causing the active chemicals
to be more or less biologically available.
3.4 Robustness of the approach
The Bulk Sediment Toxicity Test Approach is extremely robust
because sediment toxieity tests for certain species have been
widely used, method* are being standardized, and the data
interpretation of the results is understood.
3.5
Research r
Research to expand the battery of both freshwater and marine
test species that can be used in the Bulk Sediment Toxicity Test
Approach is nee^M A*, present, there are only a limited number
of species available. This is particularly true for marine and
estuarine organisms. Methods are needed which better assess
chronic toxicity and other effect-, endpoints such as
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reproduction, growth, teratogenicity or genotoxicity.
Appropriate sampling, handling, and testing methods for sediment
to be used in the Bulk Sediment Toxicity Test Approach should be
determined. Improper sampling, handling, and storage of sediment.
samples may complicate the interpretation of contaminant effects.
4.0 SPIKED SEDIMENT TOXICITY TEST APPROACH
4.1 General description of the approach "
This approach establishes relationships between sediment
contaminants and .organisms by spiking sediments in the laboratory
with known concentrations of specific chemicals and exposing
organisms to those sediments. In that sense it is similar to the
conceptual development of water quality.data. The approach can
be useu with many different types of chemicals, potentially any
sediment, and a variety of toxicity testing methods.. It is
assumed with this test that the chemicals and biota behave the
same in a laboratory spiked sediment as they would under real
world conditions. .
4.2 Advantages of the approach
\
A major advantage of this approach is the potential to use
almost any combination of sediment and chemical. Since the
toxicity evaluation is conducted in the laboratory, it is
possible to add a wide variety of chemicals. Sediments from
diverse sources can also be used, including both marine and
freshwater. This is one of the few approaches that can
potentially address questions of chemical interactions
(synergism, antagonism, etc.), although results from mixtures
with a large number of chemicals may be difficult to interpret.
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Any of a number of toxicological methods can be used to
assess the biological impact of the added materials. These can
include acute or chronic tests with a variety of endpoints
(mortality, .growth, reproduction, cytotoxicity, respiration,
and/or alteration in development). Due to the controlled
laboratory environment, it may be possible to derive cause-and-
effect relationships from the data generated.
4.3 Limitations of the spiked sediment approach
Many of the advantages of this approach are due to the
control that the use of laboratory spiked sediments gives over
the parameters to be tested. This factor is also the major
problem with the approach. The basic assumption of the method is
that "laboratory results for a given sediment and overlying water
represent biological effects of similar sediments in the field,
and that the behavior of chemicalc in spiked sediments is similar
to that in natural in situ sediments." This major assumption
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has not been justified. Real sediments contain mixtures of
materials that will be difficult to simulate in the laboratory
even if one knew the exact composition.
Major differences in sorption properties of sediment-bound
chemicals have been reported depending on whether the chemical
was artificially spiked into sediment or'occurred naturally
[Karickhoff and Morris (1985) and DiToro and Horzempa (1982)].
Slower desorption from "aged1* spiked sediments may reduce
bioavailability of contaminants, and, hence, the toxicity of the
sediments. I'f the chemicals desorb more rapidly in spiked-
sediments tests, there may be an overestimate of the toxicity.
There are insufficient data to evaluate the magnitude of this
problem and whether it applies to all classes of chemicals and
all types of sediments.
I.iere are a number of ways to incorporate or spike chemicals
into sediments. Toxicity results will likely vary depending on
whether the chemical is added to intact sediments or a slurry
approach is used. Procedures for "aging" spiked sediments should
also be addressed. The document gives little guidance as to the
nature of the various choices to be made and their significance.
4.4 Robustness of tfre approach
The approach appears to be in an early developmental stage. ,
Assuming that the proper spiking and aging scenarios are
followed, the method would require effort that is equivalent to
the Bulk Sediment Toxicity Approach. .
4.5 P *f cyiHnead a t i o a a
The spiked-sediment method is conceptually attractive
because controlled conditions can be used, specific chemicals and
mixtures assessed, and cause-effect relationships explored.
However, more data are needed on the influences of sediment aging
on sorption of spiked contaminants. Most of the testing has
involved acute toxicity tests; comparison using chronic and life
cycle tests need to be conducted. The extent to which the
approach can estimate effects from mixtures* needs to be examined.
5.0 TOXICITT IDBMTiyiCATIOM BVALUATIOKat
IMTBMTITIAL WAT8R TOXICITY APPROACH
5.X, General description of the approach '
This approach for assessing the toxicity of chemicals sorbed
to sediments is based en the idea that once a sediment is
determined to be toxic to aquatic organisms the toxieity can be;
linked to one or more chemicals. The chemical or chemicals
responsible for the toxicity ar^ then identified by taking bulk
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sediments and carrying them through various extraction or
.fractionation schemes which allow for separation of the chemicals
into chemical classes, such as organics versus inorganics and
polar organics versus non-polar organics. This is accompanied at
each step of the fractionation procedure with an aquatic bioassay
to determine the toxicity of the separated class of chemical.
Subsequently, the specific chemicals within the class are
identified using specific analytical techniques for
identification of various chemicals (e.g., HPLC, GC/MS).
5.2 Advantages of the approach
The advantages of this approach are that this is the only
method to date other than sediment spiking approaches which
describes a procedure for identifying classes of chemical agents
which may be responsible for the toxicity associated with a
particular bulk sediment. Identification of the. causative agent
potentially offers the opportunity to apply corrective action to
either eliminate the source of the problem or to remediate the
sediment. Additionally, this method should be useful for
demonstrating that site remediation has been successful in
reducing the toxicity of the sediments to aquatic life.
•" Additional advantages of this method that may be proven with
time and usage of the method include: (1) suitability for a broad
array of sediment types; (2) suitability for many different
classes of chemicals; (3) suitability for predicting effects on
several different organisms; and (4) suitability for determining
the adequacy of point-source controls.
5.3 Limitations of the approach
The state of development of this toxicity identification
evaluation (TIE) approach for sediments is in its infancy. There
are no peer-reviewed published papers at this time. Therefore,
the extent to which this method will become useful is yet to be
determined.
At the present tine one would have to list "ease of use" as
a limitation for TIE procedures, both for sediment and waste
water. Only a few laboratories can successtully perform TIE
studies. One of the main reasons is that the method requires a
high degree of skill, a multi-disciplined team, as veil as state-
of-the-art analytical capabilities for identification of specific
chemicals.
Cost is also a limitation for this methodology. Since
expenses could exceed $100,000 for samples which are highly
contaminated. In some cases cost could be much less, but it is
clearly not a routine procedure. However, in some cases the cost
of this analysis could be justified due to better data and hence
better remediation efforts.
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The level of acceptance of this method for sediments may be
a limiting factor. There are a number of scientists who believe
that the interstitial water approach for measuring sediment
toxicity underestimates the potential toxicity of chemicals
sorbed to sediments. This is because the availability of
contaminants sorbed on particles is not taken into account. For
some species ingestion may be the primary route of chemical
uptake.
The method is somewhat limited by the fact, that the sediment
interstitial water samples must come from the site of concern and
that a sufficiently large amount of sediment and water must be
collected and stored for extended periods of time. To insure the
integrity of the interstitial water, .the sediment samples often
are processed on site. This increases the level of complexity
required for obtaining samples.
There is no universally accepted method for collecting
sediment interstitial water from sediment nor is there any
consensus that the chemical properties of interstitial water
collected from laboratory or field sediments are the same as that
which exists in situ. Several of the steps in the TIE evaluation
can introduce chemical artifacts or contaminants which
necessitate the use of both positive and negative controls.
The approach is theoretically suitable for application to a
wide variety of organisms, but to date it has only been validated
using freshwater sediments and Pimephales promelas. Ceriodaohnia
sp.. and Daphnia roaana. Although other organisms can be used, a
significant amount of .baseline data is needed for these other
species (e.g., hew much methanol, EOT A, or thiosulfate can be
tolerated?, what is the background control mortality?).
5.4 Robustness of the approach
The information presented is basically sound. However the
method is in an early stata of development. Most of what the
authors have presented is speculation about how the method should
perform and how it could be used for various sediment assessment
purposes. The comment*, to a large extent, are based on data
developed for wastevater TIEs and there are only a few
laboratories that have successfully performed these tests. The
application of these same wastewater procedures to sediment
interstitial water has been performed at only one laboratory to '
date. Therefore, it is premature to draw conclusions as to their
ease of use or direct application for sediment interstitial water
samples. This is because humic and fulvic acids, as well as
other substances that could bind materials in sediments, present
special problem? *-h*.t vill have to be overcome.
It appears to offer a useful tool for evaluating sediment
toxicity. This method should not be presented as one which is
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ready for use, but rather.as one that is being considered for
future development because it appears to be .very promising.
Sections 2.2,2.3 and 3.1 should be rewritten to reflect this
viewpoint. ~ .
It is stated on page 4-4 "the major assumption of the method
is that chemicals that cause toxicity in pore water,are the same
as those chemicals that cause toxicity in the sediment1'. In
addition to this assumption, it should be mentioned that the
current procedure measures acute toxicity to a surrogate sediment
organism fCeriodaohnia sp.1 and it is assumed that this organism
is as sensitive or more sensitive than representative sediment-
dwelling organisms. This method also implies that the chemicals
causing acute toxicity will cause chronic toxicity. This
probably is not the case.
In applying this method for iri-place pollutant control
(section 3.1.4) the authors have crossed the line between using
interstitial water for identifying the toxic component and using
interstitial water toxicity tests as a way of controlling and
monitoring pollution. - The thrust of the present paper is not
aimed at demonstrating that an interstitial water toxicity test
is the best approach for monitoring sediment toxicity, but .only
that it appears to be the best for toxicant identification.
This approach is described as being suitable for source
control. This may or may not prove to be true depending on cost,
ease of use, reliability, etc., all of which have yet to be
determined. It appears to be useful to identify toxic components
in sediments. Ccl.Cu- -..-[.are simple toxicity procedures may be more
suitable for routine source control monitoring.
5.5
endatioas
The title of this method could be changed to be more
descriptive of the procedure described. The existing title
( Interstitial Water Toxieity Approach 1 would lead one to believe
that this is a sediment classification method based on an
approach similar to the Equilibrium Partitioning Approach. What
is really described is a sediment toxicity identification method.
The title could be modified to read: Sediment Toxic itv
Identification Evaluation? Interstitial Water Approach.
It is recommended that additional research be done to
evaluate the applicability of TIE procedures to sediments.
Initial research efforts need to concentrate on: developing the
necessary separation steps for sediments, developing several
sediment inter s*^*-*al bioassays, and publishing data sets for
several different sediments and different chemicals.
It is difficult to assess s-.^rgistic and antagonistic
10
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interactions in TIE procedure & •>
indicate that synerqism rarafj" A lar?e aiaount °f data now
aquatic organisms? ^atements r^Sina"^? toxicity test with
synergism are pure speculat^ SS'JiSStS^g" and '
The authors should acknowledge 'that other TTF .„•.
^r»s^^
M
Equilibrium Partitioning (EqP) is a method which predicts
concentrations of chemicals in pore water from the concentrations
sorbed to sediments. It is assumed that hydrophobic chemicals
partition to the organic carbon portion of the sediment and that
the ratio of chemicals between organic carbon and pore water is
approximated by the n-octanol-water partitioning coefficient.
Therefore, if one knows the fraction of organic carbon in the
sediments, the n-octanol-water partitioning coefficient, and the
"safe" level for a chemical in water, one can calculate the
acceptable concentration of the material in sediment.
6.2 Advantages of the approach
The method relies on a fundamental chemical parameter,
fugacity. The jj-octanol-water partitioning coefficient (K0-) is
rather easily measured, and therefore, these data are often
available for given chemicals. When a concentration of a
chemical is known in one medium, such as sediment, the
concentration can be predicted in water, within certain
confidence limits and subject to some restrictions. The method
reduces the amount of analytical work necessary and thus provides
a quick and relatively easy method to make preliminary estimates
of concentrations in interstitial water. This, when compared to
water quality criteria concentration, forms a basis for
estimating whether the surrounding sediment concentrations are of
suitable quality.
6.3. Limitations of thm approach
There is great lack of understanding of the uncertainties
associated with the basic assumptions used in this approach. For
instance, does all sediment organic carbon sorb/desorb
hydrophobic chemicals equally? How well does the octanol-water
partitioning coefficient approximate the sediment partitioning
coefficient normalized to organic carbon? Is the only
biologically available fraction of a hazardous chemical that
which is dissolved? There are only a limited number of water
quality criteria available for contaminants associated with
sediments. Sediments in the field may not be in equilibrium.
I
11
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The availability of compounds associated with' sediment may be
controlled by kinetics rather than partitioning. These and other
limitations have been presented in a previous Science Advisory
Board evaluation of this method (EPA-SAB-90-006, 1990) . Without
a better understanding of these uncertainties, the accuracy and
precision of the method will remain in doubt.
6.4 Robustness of the Approach
The usefulness of the approach will be limited by three
factors. The first, as mentioned above, relates to the
uncertainties inherent in tha assumptions. The second is that
the method, as presently proposed, should relate to water quality
criteria or other we 11 -documented protective dissolved levels of
chemicals. There are very few of these for chemicals associated
with sediment. The third limitation is that the method, as
constructed, is not intended to evaluate effects from complex
mix.urjs of contaminants sorbed to sediments.
6.5
The uncertainties in all of the assumptions used in
determining the EqP should be determined along with the
.probability of cumulative errors in each step of the
calculations. Validation experiments should be conducted using
natural or spiked sediment to determine the influence of aging on
the biological availability of chemical (s) in question. These
and other recommendations concerning needed research and
validation .exercises are given in the previously mentioned
Science Advisory Board review (EPA-SAB-EPEC-90-006) .
7.0 Tiastre
APPROACH
7.1 General description of the approach
The Tissue Residue Approach involves determining
concentrations of contaminants sorbed to sediments above which
the associated biota will contain unacceptable tissue residues.
Key to success of the method is the determination of acceptable
tissue concentrations. Two basic approaches can be used to
determine these levels. One is to establish Maximum Permissible
Tissue Concentrations (MPTC) for an organism at the chronic water
quality criterion concentration. An assumption that is made in
this approach is that body burden of a contaminant is correlated
to a toxic effect. Once this number is known, calculations to
determine acceptable water concentrations resulting from sediment
levels (e.g., the Equilibrium Partitioning approach) can be made.
Field observations which compare tissue residues to associated
sediment contaminant concentrations can also be used to derive
sediment quality ,aiuet».
i
Another approach to determining an acceptable tissue
concentration is to use a human tvilth Action Level or Tolerance
.12 .
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Level for a contaminant in freshwater fish or in seafood and
back-calculate the level in sediment that would result in these
concentrations.
The linkage between tissue residues and associated sediment
concentrations can be approximated through either site-specific
observations, equilibrium partitioning modeling, or
pharmacokinetics-bioenergetics modeling.
7.2 Advantages of the approach
There are a number of advantages to this approach if
properly executed and validated. One is that, in many cases,
direct field observations can be made to relate sediment and
tissue concentrations. For example, kepone concentrations were
found in the James River sediments and correlated to
concentrations in fish and shellfish inhabiting the river. In
such a case, the methodology does not require a knowledge of
bioavaliability relationships, because the organisms have already
integrated all the variables. Care must be taken, however, to
properly interpret the tissue residue data relative to spawning
cycle, time of year and migratory patterns. For instance, should
tissue residues be measured immediately after spawning, total
body burdens of lipophilic chemicals which had concentrated in
the eggs, would be less than before spawning. "Acceptable
sediment levels" based on these post-spawning measurements may
not be appropriate for pre-spawning conditions.
There is. greater uncertainty generated when
pharmacokinetics-bioenergetics modeling is used. This is because
of uncertainties associated with the assumptions used in the
models. For the same reasons, there are uncertainties inherent
with the use of equilibrium partitioning models to back-calculate
acceptable sediment levels. •.
7.3 Limitations of this Approach
The approach works best for aquatic ecosystems that are
close to steady state. The fact that some chemicals are
metabolized to substances of higher toxicity, and that such
transformations must be recognized for the approach to be valid,
is acknowledged in the Compendium. One limitation that needs to
be documented is the fact that our data base and understanding of
the relationship between body burden and toxicity is virtually
non-existent. While this may be less of a problem if one uses
species for which tissue residues have been measured at the
chronic water quality concentration, extrapolation to other
species is extremely risky.
The document does not adequately address which tissues are
most appropriately used. This aspect needs further.expansion.
The ability of the method to assess effects of complex mixtures
- 13
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in sediments should also be better explained.
There are real-world examples which support the utility of
this approach. There is also research which shows that
laboratory derived bioconcentration factors and depuration rates
are not always the same as those observed in the "real -world."
Therefore, extreme caution must be used when applying this method
without field validation. This is an area deserving of more
research effort.
i
7.4 Robustness of the Approach '
i ' ' /
The method has been used in the field and had been shown to
be effective. A major advantage is realized when correlations
between sediment contamination levels and tissue concentrations
can be made in the environment. Such relationships derived in
the laboratory have greater uncertainties which carry over to
sediment quality values thus derived.
7.5
It is recommended that this method be considered by the
Agency for further development as a major tool in assessing
sediment quality. Research should be supported to better define
the relationships between tissue resides and toxicities. Should
a mechanistic understanding be obtained, the method will have a
much broader 'applicability.
8.0 FRESHWATER BBMTHIC MACRO INVERTEBRATE COMMUNITY STRUCTURE AND
FUNCTION APPROACH. .
8.1 General description of approach
This is an integrated approach which utilizes sediment
chemistry, sediment toxicity, and benthic macro invertebrate
community structure and function to evaluate sediment quality, in
a manner similar to the approaches now used to evaluate surface '
water quality. The community structure and function of benthic
macro invertebrates are used extensively to evaluate water quality
and characterize impacts in lotic and lentic freshwater
ecosystems. Benthic aacro invertebrates inhabit or depend upon
the sedimentary environment for their various life functions,
therefore, they are sensitive to both long-term and short-term
changes in sediment and water quality.
The structural assessment relates to the numeric taxonomic
distribution of the community, and the functional assessment
involves trophic level and morphological aspects. The proposed
methodology addresses tiie specific benthic community assessment
methods that are available, or being developed, to complement the
chemical and toxicological portions of this sediment quality
assessment.
14
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Freshwater benthic inacroinvertebrate communities can be used,
to assess sediment or water quality in the following ways:
(a) identification of the quality of ambient
sites through a knowledge of the pollution
tolerances and life history requirements of
benthic macroinvertebrates,
(b) comparison of the quality of reference (or
least impacted) sites with test (ambient)
sites, and
(c) determination of spatial gradients of
contamination for point or diffuse source
characterization*
8.2 Advantages of the approach
Perhaps the main advantage .of using a variety of benthic
macroinvertebrate measures is that, in many cases, it can provide
an economical and useful indication of the comparative health and
well-being of the specific aquatic ecosystem under study.
A real advantage is that it provides a direct observation
rather than theoretically derived data. A.natural real-world mix
of benthic macroinvertebrates may be more useful than a standard
list of species for a generalized bioassay or other laboratory
evaluation. Benthic macroinvertebrates provide substantial
information that the chemistry and toxicity data alone cannot
provide. ,
. The sampling strategies outlined should detect spatial
differences and temporal trends. These will assist in the
overall process of detecting, quantifying, and attributing the
source or cause of change or, also important, the lack of change.
Rapid assessment techniques can be very useful to guide
decisions as to how ouch detailed biological sampling and
analysis is required as well as the level arvl type of effort
needed for other labor-intensive, long-duration, and expensive
physical -or chemical sampling, analyses, or modeling efforts.
Full quantitative sampling is not needed to determine the
relative abundance of the various species of benthic
macroinvertebrates.
Benthic community assessments can help determine whether
sediment quality is impairing the designated uses and biotic
integrity.
-------
3.3 Limitations 01; tfra
Benthic macroinvertebrates will be effective in helping to
indicate in-place pollutant'control needs through site-specific
knowledge of surface water quality, habitat quality, and sediment
chemistry and toxicity. Optimal use of benthic
macroinvertebrates may be as part of an integrated approach as
described. But the benthic macroinvertebrate data may well be,
in some instances, more quantitative, more valid, and less
suspect than other sediment toxicity or contamination assessment
methods included in the compendium. . -
One limitation is the difficulty in relating the findings to
the presence of individual chemicals and specific concentrations
of those chemicals for numeric in-place pollutant management.
However, this is a problem for many of the methods available to
estimate sediment quality.
i >
By itself, this method should not be used to generate
chemical-specific values in situations where there are,multiple
outfalls or a number of pollutants because multiple sources or
peculiar depositional or flow patterns may make interpretations
difficult. In some less complex situations, it probably could be
the basis for remedial actions; but in all cases analysis of
benthic macroinvertebrates can be extremely helpful.
It must be realized that low community diversity can be
caused by factors other than water quality impacts including
seasonal, differences, poor habitat which may result from an
influx of clean non-toxic inorganic soil, or from some other
physical perturbation. Comparisons should be made among benthic
communities inhabiting similar substrates since different
organisms will inhabit different types of substrate.
8.4 Robustness of the approach
Benthic organisms are holistically integrating all of the
environmental perturbations which are occurring. Such
integration is ideal for assessing the overall condition of a
particular environment and is especially useful in simple
circumstances where sources or inputs of contaminants are limited
and gradients can be established. In other cases, cause-and-
effect relationships may be more difficult to determine. For
instance, navigational dredging projects are most commonly found
in highly industrialized or urbanized areas which have a wide
variety of perturbations, and navigation itself is a form of
perturbation. The physical effects of traffic and of repeated
dredging in a channel may eliminate or severely reduce the
benthic fauna, particularly in navigation channels. . .
Likewise, water quality contaminant impacts from outfalls,
thermal discharges, surface runoff, and a host of other
perturbations may completely confound any effects of sediment
16
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contaminants. Further, it must be remembered that the method is
a "snapshot in time" and the organisms present are representing
the events, and particularly the extreme events, which have
occurred over some period of time.
The method can yield two results. Either -a healthy fauna
will be found, in which case no further action is required, or
the fauna will not be healthy. In the latter, if the cause is
unknown, bioassays may be necessary to separate physical effects,
water-column effects, or episodic events. Bioassays 'might best
be used instead of benthic community assessments.
8.5
Benthic macroinvertebrates alone can be used to screen for
potential sediment contamination and source identification by
disDlaying spatial gradients in community structure, but they
should not normally be used alone to definitively determine
sediment quality or develop chemical-specific guidelines.
It is probably true that a benefit of reducing complex
benthic community measurements to a single number was that it
could be used by non-biologist decision-makers. It is still
important for scientists to be very sensitive to the needs of
decision-makers and to provide them with appropriate output or
results that will be useful in making the sort of decisions
facing them. Some discussion should be provided that would help
users balance the desirability of providing one or several
numbers. *
9*0 MARINE BENTHIC COMMUNITY STRUCTURE ASSESSMENT
9.1 General Description of the Approach
The Marine Benthic Community Structure Assessment Approach
involves a field survey that includes replicated sampling at
stations; sorting and identification of the collected organisms
to the lowest possible. taxa; and analyses of species richness,
number of individuals, diversity, and sometimes biomass. Results
of field surveys are interpreted by comparison to reference
stations (sites) which are (should be) ecologically similar.
Effects of sediment physical/chemical properties are also
integrated into data interpretations. ,
9.2 Advantages of the approach
The Marine Benthic Community Structure Assessment Approach
can directly assess sediment quality since it provides an
empirical determination of the benthic community present in a
sediment sample. When compared to reference (uncontaminated)
sites, the effects of sediment contaminants on benthic organisms
can be determined. It provides a direct in SJJtU assessment.
17
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9.3 Limitations ayfchf approach
The Marine Benthic Community'structure Assessment Approach
can not be used by itself to generate numeric sediment quality
values. The approach provides no information on the
contaminant(s) causing the effects on benthic organisms.
However, the method can be integrated into several other
approaches (i.e., the Sediment Triad and AST) "to""develop numeric
sediment values. Benthic community structure is impacted by a
variety of factors other than the presence of chemical
contaminants in sediments. Interpretation of Marine Benthic
Community Structure Assessment results must include consideration
of the influence of abiotic factors such as substrate type and
quality.
Conducting benthic surveys can be expensive and require high
levels of taxonomic expertise. Frequently, available resources
limit the design of studies and statistical power is low due to
insufficient replication.
9.4 Robustness of the approach
The assessment of benthic community structure is a direct
measure of the environmental effects of pollutants and is an
extremely robust method. In general, the comments in this
section apply equally to marine or freshwater benthic community
assessments.
9,5 Recowiftendations .
Criteria need to be developed to identify reference sites to
be used in the Marine Benthic Community structure Assessment. ,
Research should be conducted to evaluate the usefulness of
identifying marine macroinvertebrates to different taxonomic
levels (i.e., Is taxonomic family adequate or is genus always
required?).
10. 0 SEDIMENT
THAD APPROACH
10.1 General Description .
in the Sediment Quality Triad Approach, chemical analyses of
sediments, studies of .the benthic infaunal communities, and
laboratory bioassays of sediments are used to provide a
qualitative and numerical description of sediment quality. The
major emphasis has been on an integrated qualitative description
of sediment quality.
The Sediment Quality Triad Approach has many similarities to
the AET Approach, in that both methods use sediment chemistry
data, ah assessment of benthic infauna, and sediment toxicity
' ' 18 ' ' • ••
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studies. The methods
and their i
data
illustrate the degree
(RTK,
fr=» h <>"9ranMtic for. to
10.2 Advantages
The major strength of the method is that it can deal with
interactions of components in the types of mixtures that are en-
countered in a specific locality. The method integrates chemical
studies, benthic population studies, and laboratory bioassays.
The method offers an integrated approach to prioritizing
areas of sedimentary contamination within a single geographic
region. '
l°-3 Limitations
l
The major weakness of the Triad method is its site-
specific nature. In addition, the Triad method does not
establish causal relationships between specific contaminant
concentrations and observed adverse effects. In its original
form the Triad method does not develop numerical sediment quality
values. Data aener^t-.ed may be difficult to interpret if
normalizing factors for bioavailability are unknown.
10.4 Robustness of the method
Conceptually, within its limitations, the method is robust.
The reliability of the individual Triad prioritizations is
strongly influenced by the quantity and quality of the data
available for integration.
10.5 PT??IBni*Bflflt^-o**a ' '
The section on the Triad Approach is veil written. The
write-up of the Triad method should make more explicit references
to the AST approach, briefly indicating similarities and
pertinent differences.
19
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11.0 APPARENT EFFECTS THRESHOLD APPROACH
11.1 General description of the approach
For the Apparent Effects Threshold (AET) approach,
biological data (e.g., benthic community structure or laboratory
bioassays) and chemical analyses of contaminants in sediments
are used to develop sedimentary concentration limits for
specific contaminants.
The AET Approach has many similarities to the Sediment ,
Quality Triad Approach, in that both methods use sediment
chemistry data, an assessment of benthic infauna, and sediment
toxicity studies. The methods used for the analysis of the
resulting data and their interpretation in these two methods
differ.
The AET method was originally developed to evaluate
conditions in Puget Sound on the basis of an extensive data set
that was available for that region.
This method received extensive evaluation by EPA's Science
Advisory Board (SAB), and the reader is referred to the report
of the' SAB Subcommittee on Sediment Criteria ("Evaluation of the
Apparent Effects threshold Approach for Assessing Sediment
Quality" SAB-EETFC-89-027, July, 1989) for their
evaluation.
The AET method 5s based upon an assessment of the
concentrationr of ' 'cilly encountered contaminants and identifies
those concentrations that are associated at some confidence
level with decrements of benthic biota. Field data may be
augmented by laboratory toxicity screening tests (e.g.,
bacterial bioluminescence, amphipod mortality,'and developmental
abnormalities in oyster larvae). The AET method can establish
sedimentary quality values on the basis of benthic infaunal
changes, or on the basis of laboratory toxicity data derived from
sediment samples, or oh some combination of both field and
laboratory data. ,
11.2 Strengths of this Method
The major strength of the method is that it can deal with
interactions of components in the types of mixtures that are en-
countered in a specific locality. Effects measured in the field
as well as in the lahoratory can be accommodated by the method.
The AET method can be particularly advantageous when many
environmental samples are already being collected as part of
other program needs. ' '
20
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/11.3 Limitations o{ this Method
The major weakness of the AET method is its
site-specific nature. AET values developed for one location
cannot be readily exported to other sites without repeating
most of the field and laboratory analyses for the new location,
so that the interactions of the various chemicals in the new
sediments.on the biota could be determined. In addition, the AET
method does not establish causal relationships between specific
contaminant concentrations and observed adverse effects. Non-
protective AETs could be generated if biological results were
incorrectly classified. By definition an AET can only increase
with additional non-impacted (e.g., incorrectly classified) data.
It also requires a large data base and is therefore costly.
11.4 Robustness ef the method
Conceptually, within its limitations, the method is robust.
The reliability of the individual AET values is strongly
influenced by the quantity and quality of the data "available for
their derivation.
The presentation of the AET method needs to be revised.
Host of Chapter 10 deals with the history, derivation, and
potential uses of the AET method. The discussions of the AET
method should make reference to the Sediment Quality Triad
Approach, briefly indicating similarities and pertinent
differences. In an earlier evaluation of the AET method, this
Subcommittee recommended that EPA use the AET method in
combination with other approaches and that the AET approach could
be strengthened by using replicate sediment samples, devising
criteria for selecting reference sites, including considerations
of physical factors, and developing measures of variance.
12.1 general description of the approach
The approach developed by the International Joint Commission
(IJC) for the assessment of contaminated sediments in the Great
Lakes differs significantly from the other approaches cited in
the "Sediment Classification Methods Compendium." The approach
emphasizes strategy rather than methodological details. The IJC
method is focused on large-scale problems and considers the cost-
effectiveness of the initial studies. The major concerns are the
21 . ' •
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potentials for. biological effects and bioconcentration. The
strategy employs .chemical, physical, and biological approaches to
define the qualitative and quantitative severity of an impact.
The strategy is comprised of a series of data-gathering
activities: physical mapping, including benthic communities;
laboratory bioassays; and characterizing sediment dynamics, which
may be important in developing remedial options.
12.2 Strengths of this Approach
The major strength of the method is the recognition of
the need for a strategy to attack a series of problems that may
range from the small to problems of major extent. The IJC
approach clearly recognizes the need to reconcile the costs of
the investigation of sedimentary quality with the costs of any
remedial actions, and provides general guidance for a threshold
for investigating sediment associated problems. In addition,
the IJC approach recognizes the need for using multiple avenues.
to demonstrate the extent and depth of the problem.
12.3 Limitations of this Approach
The method has the earmarks of a process developed in
a conference room, rather than being developed in accordance
with field experience. The magnitude of required data for Stage
I is irreconcilable with a strategic approach that would
sequence a reconnaissance investigation with a more descriptive
investigation, followed by a detailed investigation targeted at
remediation, followed by a compliance investigation during and
after the remediation process. Furthermore, the strategy for
Stage I comb?ret aspects that are extremely specific (e.g., the
analysis of phosphorus) with aspects that are poorly specified
(e.g., benthic community structure). Ideally, the initial
reconnaissance studies should be the least expensive, the most
general, the most inclusive, and the least definitive. This is
clearly not the case for the IJC method, where stages I and II
are the most expensive.
The specifications for additional phases and stages
considerably in the general guidance and specificity of
instructions that are provided.
vary
The discussion of the IJC method in the Methods Compendium
needs to be improved with regard to any distinction between
stages and phases in the methodology.
12.4 Robustness of the approach
The IJC method is fragile. It has not been proven in the
assessment of actual environmental conditions. Nevertheless,
certain aspects of this methodology deserve their generalized
incorporation into any comprehensive methodology. Thus, this
22
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overall strategy for dealing with contaminated sediments is so
valuable that it should be incorporated into all methodologies
associated with the evaluation of sediments. Although the IJC
method was designed specifically for the Great Lakes, its
present methodology is so general that it can be applied
globally; the only exceptions to this may be the emphasis of
the Great Lakes method on bioconcentration and on finding
tumors in fish. However,, these latter two issues may well be
sufficiently important that they should receive priority
treatment for the evaluation of sediments in other localities.
Many of the specific methodologies cited as part of the
approach have also been -cited previously as part of other
approaches, especially in the Sediment Triad and the AET
methodologies.
12 . 5 y
uc
Regardless of the .shortcomings of the IJC
methodology, the concept of using a strategy to attack
complex problem has a great deal of merit. It is important
the concepts of IJC strategy be incorporated into the
resolution of all complex approaches on the potential effects
contaminants in sediments.
this
that
of
13.0 SUMMARY OF PINDINQfl AMP RBCOMMgMPMIONa
N f > '
A. The Subcommittee finds that the Compendium is scientifically
acceptable for its intended use and encourages EPA to expand the
introduction with references and discussion for sample collection
and handling, quality assurance/quality control, tiered
approaches for mixtures of chemicals, and data analysis. The
Subcommittee also suggests that EPA add a table to the Compendium
that summarizes information on the status and relative costs of
each method. The status information could include relevant and
comparative information on: the number and type of species
tested, site specificity, field validation, and the availability
of an uncertainty analysis for each method.
B. The Subcommittee recommends that EPA conduct research to
expand the battery of freshwater and marine species that can be
tested in the Bulk Sediment Toxicity Test Approach. For all
approaches, protocols should be developed for handling and
collecting samples, for sample storage, and basic quality
assurance procedures. This could be added as introductory
material to the Compendium or published as a separate document.
Additional test methods are needed to assess other endpoints,
such as chronic toxicity and teratogenicity.
23
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-C. The Subcommittee recommends that EPA investigate the effect
of the effect of "aging" of spiked sediments and examine the
extent to which the Spiked Sediment Toxicit'y Approach can be used
to estimate the effects from mixtures.
D. The Subcommittee recommends that EPA revise the discussion
of the Interstitial Water Toxicity Approach to emphasize its
strengths for identifying sediment toxicity. Additional research
should be performed to evaluate the applicability of the TIE
procedures to sediments.
E. The Subcommittee reiterates its recommendations from an
earlier review of the Equilibrium Partitioning approach (EPA-SAB-
EPEC-90-006, February, 1990). The compendium should caution
users of this method to express the uncertainties in the
assumptions and to avoid cumulative errors in the calculation of
the partition values. The availability of compounds associated
witn sediment may be controlled by kinetics rather than by
partitioning. The possible influence of kinetics should be
considered When the equilibrium partitioning approach is used to
establish sediment quality values.
F. .The Subcommittee recommends that the EPA consider further
development of the Tissue Residue approach which has the
potential to be used as a major tool in assessing sediment
quality. The method could have even wider applicability if
research could define the mechanisms of partitioning in the "real
world" and the. relationship between tissue residues and toxicity.
G. The SubcoTuni t*.ee recommends that the Freshwater and Marine
Benthic Macroinvertebrate Community approaches be used to screen
for potential sediment contamination and source identification.
Discussion should be added to the compendium to help users
balance the desirability of providing one or several numbers, and
guidance should be added to identify reference sites for the
Marine approach.
H. The Subcommittee recommends that the Sediment Triad and the
Apparent Effects Threshold (ACT) approaches should be cross-
referenced* Additional comments were provided on the AET
approach in a separate report (EPA-SAB-EEFTC-89-027, August, ,
1989).
I. The Subcommittee recommends that EPA highlight the
International Joint Commission Sediment Strategy for its
conceptual strength toward addressing the potential effects of
contaminants in sediment.
24
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14.0 REFERENCES CITED
•j
DiToro, D.M. and L.M. Horzempa'. (1982) Reversible and
Resistant components of PCS adsorption-desorption isotherms.
Environ. Sci. Techn. 1Ł{9) :59.4-602.
Dbi J. and D..Grothe, 1988. Use of fractionation chemical
analysis schemes for plant effluent toxicity evaluations.
Aquatic Toxicology and Environmental Fatei Eleventh Volume, ASTM
STP 1007, G.W. Suter II and M.A. Lewis, Eds., American Society
for Testing and Materials, Philadelphia, pp. 123-138.
KaricJchoff, S.w. and K.R. Morris. (1985) Sorptionr dynamics of
hydrophobia pollutants in sediment suspensions. Environ.
Toxicol. Chem. 1:469-479.
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