Proceedings of the U.S. Geological Survey (USGS) Sediment Workshop,
February 4-7, 1997
U.S. EPA'S CONTAMINATED SEDIMENT MANAGEMENT ACTIVITIES:
GOALS, OBJECTIVES, AND SUPPORTING RESEARCH NEEDS
By Tom Armitage, U.S. Environmental Protection
Agency
Contaminated sediment in water bodies of the U.S. has emerged as
an ecological and human health issue of national proportions. Contaminated
sediment can be associated with acute and chronic effects on aquatic life.
Sediments also constitute a major source of persistent bioaccumulative
toxic chemicals which may pose threats to ecological and human health even
after contaminants are no longer released from point and nonpoint sources.
Documented adverse ecological effects of contaminants in sediments
include: fin rot, skin lesions, increased tumor frequency, and
reproductive toxicity in fish; reproductive failure in fish-eating birds
and mammals; and decreased biodiversity in aquatic ecosystems. Threats to
human health occur when sediment contaminants bioaccumulate in fish and
shellfish tissues consumed by humans. Fish advisories have been issued for
more than 1,500 water bodies in 46 states for pollutants such as mercury,
dioxins, PCBs, PAHs and pesticides such as chlordane (a banned pesticide)
and chlorpyrifos (a pesticide currently registered for use).
More than ten Federal statutes provide authority to many EPA program
offices to address the problem of contaminated sediment. These statutes
include: the National Environmental Policy Act; the Clean Air Act; the
Coastal Zone Management Act; the Federal Insecticide, Fungicide, and
Rodenticide Act; the Marine Protection, Research, and Sanctuaries Act; the
Resource Conservation and Recovery Act; the Toxic Substances Control Act;
the Clean Water Act; the Great Lakes Water Quality Agreement of 1978, and
the Comprehensive Emergency Response, Compensation, and Liability Act. A
complete summary of EPA statutory authorities for addressing sediment
contamination is provided in Contaminated Sediments - Relevant Statutes
and EPA Program Activities (U.S. EPA, 1990).
The major goals of EPA programs with authority to address contaminated
sediment are reflected in the Agency's Contaminated Sediment Management
Strategy published for public review and comment in August, 1994 (U.S.
EPA, 1994). These goals are: (1) prevent further sediment contamination
that may cause unacceptable ecological or human health risks; (2) when
practical, clean up existing sediment contamination that adversely affects
the Nation's water bodies or their uses; (3) ensure that sediment dredging
and dredged material disposal continue to be managed in an environmentally
sound manner; and (4) develop methodologies to enhance the capability for
assessment of sediment contaminants. A number of program objectives are
being pursued by EPA to meet these goals. These program objectives
include:
- Developing scientifically sound assessment tools to determine
sediment quality;
- Identifying and controlling ongoing point and nonpoint sources of
sediment contamination;
- Linking contaminated sediment site data to sources of contamination;
- Identifying and ranking, in priority order, contaminated sediment
sites, sources of pollution, and controls using a watershed approach;
- Achieving natural recovery of contaminated sediments by reducing or
eliminating sources of contamination;
- Remediating high priority contaminated sediment sites where pollution
prevention/source controls will not allow sediments to recover naturally
in an acceptable period of time.
- Ensuring an ecologically relevant dredged material disposal permitting
process that protects aquatic resources; and
- Developing cost-effective, environmentally sound options for disposal
and management of contaminated dredged materials.
A comprehensive and well coordinated contaminated sediment research
program will support many of these EPA program objectives. Research should
be conducted to identify relationships between sediment contaminants and
the viability and sustainability of benthic ecosystems. The results of
such research can be used to direct cost-effective source control and
pollution prevention strategies. Research to address critical
uncertainties in the areas of contaminant effects, exposure assessment,
and the treatment of sediments can also support risk-based decision
making. Four categories of contaminated sediments research needed to
support EPA program objectives can be identified as follows.
-
1.
- Extent and severity of sediment contamination.
Data from analysis of high quality, representative samples are needed to
better understand national and regional trends in concentrations of
organic and inorganic sediment contaminants, sediment toxicity, and
benthic community composition and abundance.
-
2.
- Methods and data to assess ecological exposure and effects
of sediment contaminants. Priority needs include the development
of: (a) data on the ecological consequences of sediment contaminants at
the population, community, and ecosystem scales ; (b) data on tissue
residue thresholds and models for assessing lethal and sublethal effects
of bioaccumulative sediment contaminants; (c) data on the fate and
transport of contaminants and how these factors influence exposure and
bioavailability; (d) field-validated sediment toxicity assessment methods
to evaluate impacts on individual test species as well as on populations
of benthic organisms; (e) methods for determining the effects of mixtures
of contaminants on sediment toxicity; and (f) refined models for
determining the fate and transport of sediment contaminants.
-
3.
- Development and validation of chemical-specific sediment
quality criteria. Techniques for the derivation of numerical
sediment quality criteria for both marine and freshwater systems should be
developed and field validated through research activities such as: (a)
field and laboratory studies to validate equilibrium partitioning for
different classes of contaminants and associated tissue residue approaches
for deriving sediment quality criteria; (b) studies to determine the
physical and chemical factors in sediments which mediate the
bioavailability and toxicity of metals and ionizable organic chemicals;
(c) studies to develop food chain models for predicting the exposure of
higher trophic level organisms, and (d) studies to evaluate the efficacy
of sediment criteria to protect benthic and fish assemblages at the
population, community, and ecosystem scales.
Studies are also needed to derive chemical data for development of
sediment quality criteria. Research can be conducted to determine
octanol/water partition coefficients for hydrophobic organic compounds,
investigate sorption-desorption kinetics of organic pollutants,
investigate mechanisms by which organic contaminants and medals adsorb to
sediment, and to develop and validate models for binding and release of
metals to sediments. Research is also needed to develop chemical and
biological transformation pathway/kinetic data for ionic and nonionic
organic contaminants for development of sediment quality criteria.
-
4.
- Development and evaluation of sediment cleanup
methods. Research is needed to develop and evaluate a range of
cost-effective remediation technologies for contaminated sediments, with
emphasis on in situ containment, biological treatment, and metals
treatment. Such research may focus on capping or armoring of sediment for
in situ containment, on the use of confined disposal facilities such as
large bioreactors to degrade contaminants, and on development of
technologies for removal, recovery, and eventual reuse of metals from
sediments. Research is also needed to determine the rates of recovery of
benthic communities under different environmental conditions and stresses,
for use in developing criteria to determine when natural recovery is the
appropriate remedial alternative.
In undertaking research to support contaminated sediment program goals and
objectives, EPA will benefit from working closely with a number of other
Federal agencies and stakeholders to ensure that the methods, tests, and
models developed are useful to EPA program offices and other identified
users of research products. The Agency's Contaminated Sediment Management
Strategy states that EPA can most effectively manage the problem of
contaminated sediments by drawing upon the technical expertise available
in other government agencies, academia, and industry, and coordinating EPA
research and management programs with the ongoing activities of these
other agencies and stakeholders.
References
U.S. EPA. 1990. Contaminated Sediments-Relevant Statutes and EPA Program
Activities. EPA 506/6-90/003 U.S. EPA. 1994. EPA's Contaminated Sediment
Management Strategy. EPA 823/R/94/001
Workshop Proceedings
Contributions from Other Federal Agencies
Contribution from the USGS