Urtitad Sain 0
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ef(\ 06 ^
q¥ Property of U.S. Environmental
Protection Agency Library MD-108
JAN I 3 1383
- v^®1* 1200 Sixttl Avenue/Seattle, WA 98101
.«»»•< 5
Se?t
Environmental Protection Agency
Criteria and Standards Division
Office of Water Regulations and Standards
Washington, B.C. 20960
Prepared by:
JRB Associates
8400 Westpark Drive
McLean, Virginia 22102
EPA Contract No. 68-01-6388
JRB Project Ho. 2-813-03-852-84
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TABLE OF CONTENTS
Page
1. INTRODUCTION ^
2. ALTERNATIVE METHODOLOGIES FOR CRITERIA DEVELOPMENT 2-1
2.1 BACKGROUND APPROACH 2-1
2.2 EPA WATER QUALITY CRITERIA APPROACH 2-4
2.3 EQUILIBRIUM PARTITIONING APPROACHES 2-6
2.3.1 Sediment-Water Equilibrium Partitioning 2-7
2.3.2 Sediment—Biota Equilibrium Partitioning. ....... 2-11
2.4 BIOASSAY APPROACH 2-14
2.5 SUMMARY OF METHODOLOGIES 2-15
3. APPLICATION OF SEDIMENT CRITERIA 3_i
3.1 DEVELOPMENT OF NPDES PERMITS 3-1
3.2 ISSUANCE OF CWA SECTION 301(H) PERMITS. . 3-3
3.3 ISSUANCE OF PERMITS UNDER SECTION 404 OF CWA 3-6
3.4 OCEAN DISCHARGE/OCEAN DUMPING PERMITTING 3-7
3.5 EVALUATION OF REMEDIAL ALTERNATIVES AT SUPERFUND SITES. . . . 3-8
3.6 IDENTIFICATION OF HAZARDOUS WASTE UNDER RCRA 3-10
4. REFERENCES 4-1
APPENDIX A
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1. INTRODUCTION
The principal objective of the Criteria and Standards Division (CSD) in
supporting the mandate of the Clean Water Act (CWA) is to develop and revise
criteria, regulations, standards, and guidelines. Under Section 304(a)(1) of
the CWA, the Environmental Protection Agency (EPA) is requested to publish and
periodically review water quality criteria that reflect the latest scientific
knowledge. These criteria, developed by CSD, provide the scientific basis
underlying the efforts of EPA to restore and protect the integrity of our
water resources. To date, water quality criteria for the protection of
aquatic life and human health have been published for the 65 priority
pollutants and pollutant categories. New criteria for ammonia and chlorine
and revised criteria for certain heavy metals were proposed in 1984.
Water quality criteria are supported by a broad base of toxicological
studies of a range of organisms and are a best estimate of the concentration-
effect relationship. Acute and chronic aquatic life criteria specify
pollutant concentrations that, if not exceeded, will protect the designated
use of the water body, and 95 percent of the aquatic life from adverse
effects. Human health criteria are estimates of ambient water concentrations
that may be used to protect against adverse health effects in humans. In the
case of carcinogens, ambient water quality criteria are expressed as levels of
incremental cancer risk.
EPA has established criteria on which to assess the significance of
contamination and on which to base regulatory control and enforcement
activities. Implementation and enforcement of these criteria provide some
degree of assurance that contaminant concentrations will be within the
acceptable limits for protecting aquatic life and human health. While ambient
water quality criteria have been and should remain an important component of
the efforts to maintain environmental quality, there is a growing national
recognition of the need to supplement water quality criteria with some form of
sediment-related criteria.
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Sediment criteria would provide a basis for EPA to evaluate and regulate
Che discharge of pollutants that are likely to produce unacceptable adverse
effects in. freshwater and marine organisms. A number of attributes of
sediments make sediment criteria inherently desirable:
• While many of the compounds of environmental concern, including both
trace metals and synthetic organics, are often found in only trace
Quantities in the water column, they attain concentrations several
orders of magnitude greater in the sediments.
• Sediments serve as a reservoir for many pollutants; thus, a long-term,
low-level discharge of a pollutant can result in high concentrations
of the substance in the sediment without ever violating water quality
criteria.
• Sediments can function as a source of contaminants to unpolluted
overlying water.
• Sediments integrate contaminant concentrations over time, thereby
avoiding the high temporal variability encountered in water column
s amp1ing•
« For benthic organisms the concentration of contaminants in the
sediment, rather than in the water column, may be a controlling factor
in bioaccumulation.
In this background document, the approaches en w .
PP °aches Co ^eloping of sediment
criteria are summarized, and their potential application* , T
, . . , Hpucacions are considered. It
is hoped that this document will faei ?
, lUt"' the and evaluaeion of eh.
methods currently under consideration by the 8cW,t
cientitic and regulatory
community.
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2.0 ALTERNATIVE METHODOLOGIES FOR CRITERIA DEVELOPMENT
The need felt by many agencies and institutions for some criteria by
which to evaluate contaminant levels in sediments has led to the development
of a wide variety of approaches for establishing sediment quality criteria.
.The history of sediment criteria development and the wide diversity of
methodologies proposed for the derivation of criteria have been reviewed by
Pavlou and Weston (1983). The following review provides a summary of those
approaches that have received the attention of regulatory agencies and/or
that appear to hold the greatest promise for the development of defensible
criteria. The approaches discussed below include: (1) the background
approach; (2) the EPA water quality criteria approach; (3) equilibrium
approaches including sediment-water and biota-sediment partitioning; and
(4) the bioassay approach.
2.1 BACKGROUND APPROACH
Definition
Criteria are established with reference to measured contaminant concen-
trations in sediment from a specified target area, in which contamination is
considered to be very low or at least within acceptable limits.
The background approach avoids the difficult, and as yet unanswerable,
toxicological questions inherent in all other approaches to sediment criteria.
Rather than attempting to establish an environmentally safe contaminant
threshold, the approach simply establishes the criteria in relation to
contaminant concentrations in a reference area where contamination is at
acceptable levels. The methodology of the background approach can vary
considerably depending on the reference area used. In the most conservative
application, the reference sediment could be collected by deep cores in an
attempt to estimate pre-industrial contaminant levels. However, such an
approach would not be workable since some enrichment of contaminants above
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pre-industrial levels is unavoidable. In addition, it would not provide
adequate criteria for some of the synthetic organics that would be absent from
pre-mdustrial sediments, except by vertical migration. A better, though
still unsatisfactory, approach would be to use surface sediments from a
relatively uncontaminated area as the reference sediment. Though this
information would be valuable in comparing the magnitude of contamination
elsewhere, as a criterion, background levels derived from pristine areas would
prove unnecessarily restrictive, because the environment may be capable of
assimilating additional contamination without adverse effect.
In order to account for this additional assimilative capacity, it would
be desirable to establish the criteria at some permissible level of enrichment
above background. To determine this level of enrichment in a technically
defensible fashion requires a substantial amount of toxicological information
in order to establish the degree of enrichment that would be biologically
acceptable. The establishment of a permissible enrichment above background
would, in effect, then become a criterion in itself, in which case the
original background level would become superfluous (Chapman, l«H4>. Lacking
the needed toxicological data, but recognizing the over-restrictive nature of
criteria based on background levels in pristine areas, it might also be
possible to establish an arbitrary level of enrichment, though this would
raise serious doubts as to the legal and technical defensibility of such an
approach.
Criteria based on a modification of the
or cne background approach have recently
been adopted for regulatory application by EPA R»„,*
Region X and the Washington
Department of Ecology (WDOE) (U.S. EPA/WDOE 198^ tv
^• These agencies were
obligated to estabHsh decision criteria i. »<,„ co eh# ,uitabUi
of dredged material for op.n-v.cr disposal « the Fo>lr Miu ^
"" " Pu,,t SOUnd- coxicologicjlly derived criteria are
years away, the., agencies simply adopted the po.iti„„ thlt „„ f„rther
chemical or biologic,1 degradation of the Four Mil, Reck ,it, ,houid b,
allowed. If materials intended for dispel are .ore chemically contaminated
or more biologically detrimental th«n sediment, currently at the site
open-water disposal is not permitted. The approach used is uni,ue i„'th.t not
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only are background contaminant levels established, but background biological
impacts (mortality in amphipod and oyster larvae bioassays) are also
determined. The decision of whether to allow dumping of dredged material at
the site is based on the following criteria (U.S. EPA/WDOE, 1984);
Chemical Criteria
• If any pollutant, or group of pollutants, of concern is found in
concentrations greater than 125% of the ambient concentrations of that
pollutant at the Four Mile Rock site, in-water disposal will not be
allowed.
• If three or more pollutants are found in concentrations greater than
110% of the ambient concentrations of those same pollutants at the
Four Mile Rock site, in-water disposal will not be allowed.
• If one or two pollutants are found in concentrations within the range
of 110 to 125? of the ambient concentrations of those same pollutants
at the Four Mile Rock site, in-water disposal will be allowed,
provided that bioassay criteria are not exceeded.
e If all pollutants are found at concentrations of 110% or less than the
ambient concentrations for the same pollutants at the Four Mile Rock
site, in-water disposal will be allowed, provided that bioassay
criteria are not exceeded.
Biological Criteria
• If the mean amphipod mortality or oyster larvae mortality/ abnormality
is statistically less than or equal to the mean mortality/abnormality
at the sites near the Four-Mile-Rock site, in-water disposal will be
allowed, provided that chemical analysis criteria are not exceeded.
# If the mean amphipod survival or oyster larvae mortality/abnormality
is statistically greater than the mean survival/abnormality at the
sites near the Four Mile Rock site, in-water disposal will not be
allowed.
Advantages
• Given the inadequate data available on toxicity of sediment-
associated contaminants, some form of the background approach
provides the only means currently available to establish interim
chemical criteria for sediments.
• The field data necessary for application of the background approach
are already available in many areas or can be obtained relatively
easily.
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Disadvantages
• Many forms of the background approach are of questionable legal and
technical defensibility.
• Criteria would be extremely site specific, determined largely by
the stations chosen to represent "background."
• Criteria may be unrealistic and too restrictive since there is no
attempt to define a maximum, biologically safe level of contamination.
2.2 EPA WATER QUALITY CRITERIA APPROACH
Definition
Contaminant concentrations in interstitial water, rather than in bulk
sediment, are measured and compared to EPA water quality criteria.
Methodology
This approach was developed in EPA Region VI as a method of applying the
toxlcological data base associated with existing water quality criteria to
sediments. Interstitial waters were considered to be an extension of the
overlying water column and therefore in need of the same level of protection.
Existing EPA water quality criteria, either 24-hour average concentration or
maximum permissible concentrations for the protection of freshwater aquatic
life, were directly applied as sediment quality indicators. Concentrations of
dissolved contaminants measured in the interstitial water were then compared
to the water quality criteria to determine whether contamination was within
permissible limits*
This approach is inherently attractive because of its simplicity, but
serious technical questions and methodological difficulties must be considered
prior to its application. This approach assumes that EPA water quality
criteria, which have been derived in sediment-free bioassays using principally
nektonic organisms, will provide adequate protection to infaunal organisms.
However, not only are infaunal organisms exposed to contaminants dissolved in
the interstitial water, but they ingest sediment particles that typically have
contaminant concentrations several orders of magnitude greater than in the
interstitial water. If ingestion of contaminated sediment contributes to
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contaminant uptake, this alone does not discount the EPA water quality
criteria approach. However, this approach, and the sediment-water
partitioning approach discussed in Section 2.3.1 assume that ingestion of
sediment does not Increase contaminant uptake above that attainable by
absorption from the interstitial water alone.
The potential for contaminant uptake by ingestion resulting in a body
burden greater than that attainable entirely from the interstitial water has
not been adequately assessed. To date-, experimental evidence has been
contradictory. In an extensive series of laboratory tests in which midges
were exposed kepone-contaminated water, sediment or food, Adams et al. (1983)
found the primary route of pollutant uptake to be from interstitial water
and/or water at the sediment/water Interface. It was suggested that a
sediment would be toxic to benthic organisms only If the interstitial water
concentration equalled or exceeded a level determined to be harmful in a
standard static bioassay. On the other hand, Fowler et al. (1978) found that
ingestion of PCB-contaminated sediment by a polychaete can dramatically
increase contaminant uptake above that attainable from the interstitial water.
A second point of concern regarding the EPA water quality criteria
approach is the necessity of measuring contaminant concentrations in
interstitial water. The methodology of interstitial water collection and
analysis is not well developed or widely practiced, especially for organic
compounds. The primary difficulties are extracting interstitial water from
the sediment without altering its chemistry and obtaining a sufficient volume
for analysis of organic compounds. In sandy sediments, collecting an adequate
volume for analysis is difficult or impossible.
Advantages
• The EPA water quality criteria approach incorporates the large
toxicological data base associated with EPA water quality criteria.
• This approach is applicable to a wide spectrum of sediment contami-
nants, including metals and organics, since direct measurements of
contaminant concentrations are used rather than concentrations
calculated on the basis of partitioning coefficients.
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Disadvantages
* waterquaU^?,CT°?,be establi8he<* tho.. compounds lacking
7 crlterla established maximum and average
concentrations; see discussion, section 2.3.1).
* I!!*8 ne8lects the potential for biota-sediment pollutant
transfer independent of uptake from interstitial water.
* w.":00""" "1Ch th* analy»' °f «ntaminants in
2.3 EQUILIBRIUM PARTITIONING APPROACHES
Definition
Distribution sufficients are used to establish a contaminant
concentration in s.diment that at equilibrium .ill yi.id an acceptable
contaminant concentration in another environmental phase, either «t.r or
tissue.
Methodology
Equilibrium partitioning approach., r.ly „„ the assumption that the
distribution of a contaminant in sediment Is solely controlled by rapid and
continuous exchange batwen the solid sediment, Interstitial and overlying
water, and indigenous biota. Under these conditions, th. equilibrium
concentration of the contaminant in a particular reservoir is a function of
its concentration in any other reservoir and an appropriate equilibrium
constant. These constants are ref.rr.d to a, partition coefficients,
bioconcentration factors, ot bioaccu.ul.tlon factors, depending on whether
abiotic or biotic reservoirs are being considered. They are expressed
mathematically as:
(1)
where K equals a distribution coefficient at equilibrium and C* and C* equal
the concentration of contaminant x in reservoirs i and j, respectively.
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Values of K can be derived theoretically (Hansch and Leo, 1979) or empirically
through laboratory or field studies (Karickhoff, et al., 1979). to determine
sediment criteria using an equilibrium partitioning approach, equation (1) is
rewritten as:
¦ K/t (2>
where C* equals the criteria concentration in sediment and equals an
acceptable contaminant concentration in water or tissue.
Using this equation, known values for K, and maximum allowable values of
C*, derived from water quality standards or permissible tissue levels, it is
w/1
possible to calculate sediment criteria that are consistent with these
standards.
2.3.1 Sediment-Water Equilibrium Partitioning
Definition
The concentration of a contaminant in sediment is established at a level
that ensures that its concentration in the interstitial water does not exceed
the EPA water quality criteria.
Methodology
A detailed description of the sediment-water partitioning approach can be
found in JRB Associates (1984) and consequently only a summary is provided
below. As is the case for the water quality criteria approach (Section 2.?),
the sediment water equilibrium partitioning approach is based on the premise
that existing EPA water quality criteria, when applied to the interstitial
water, provide adequate protection to infaunal organisms. Compound-specific
partitioning coefficients are then determined, and these may be used in
predicting the distribution of the contaminant between sediment and
interstitial water as follows:
"d-_
C*
1W
(3)
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where ^ in the partition co.ffici.nc «nd cj and at« che concentrations of
contaminant * in Che sediment(s) and incerscitial wat.r (IW), respectively.
The distribution of most contaminants between »acer and sediment is strongly
influenced by the amount of organic carbon in Che sediments; sediment, with a
high organic content having the greatest affinity for contaminants. Thus it
is .ore appropriate to express the partition coefficient in tern., of organic
content:
OC
1
TOC
D
TOC
(A)
1W
where ia the organic carbon normal i»«,j • .
oc normalized partition coefficient and TOC is
the total organic carbon content of t-h» „«j-
the sed">ent expressed as a fractional
mass on a dry weight basis. Settin® eh. *
. . , aeccin8 the EPA water quality criterion (C* )
equal to the interstitial water concentration (cx > ^ t J.w/cr
ration (C. ) and the corresponding
sediment concentration as the criterion (r*
icerton
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Determining of equilibrium partition coefficients for trace metals is
much more difficult than for many organic compounds. For many organic
compounds, and particularly the base neutral compounds, partitioning can be
explained largely on the basis of organic carbon content, with relatively
little dependence on other physical/chemical environmental factors. In
contrast, while trace metal partitioning is often influenced to some degree by
organic content, a wide variety of other physical/chemical factors can be even
more influential in determining the distribution of trace metals between
sediment and interstitial water. Reduction—oxidation potential and pH are
among the most important of these physical/chemical factors. Given the
current state of knowledge, it is impossible to precisely quantify the
dependence of trace metal partitioning on the many pertinent environmental
variables. Quasi-eouilibrium coefficienes, derived by empirical comparisons
of trace metal concentrations in sediment and interstitial water, have been
used to estimate sediment criteria from EPA water quality criteria (JRB
Associates, 1984). However, site-specific variation in physical/chemical
factors makes the level of uncertainty associated with these estimates
considerable, complicating the use of trace metal sediment criteria for
regulatory application.
The sediment-water equilibrium partitioning approach to sediment quality
criteria was developed in order to make use of the large toxicological data
base already incorporated in the EPA water quality criteria. For the 10 trace
metals and 10 organic compounds for which EPA water qualty criteria for the
protection of aquatic life are available, the development of sediment criteria
is straightforward. However, for most organic chemicals, no water quality
criteria are available. Instead EPA criteria documents report only the lowest
concentration at which adverse biological effects have been noted. In order
to establish sediment criteria for these compounds, it may be possible to use
one half of the lowest concentration causing effects as an interim water
quality "criterion." This procedure closely parallels the protocol followed
in developing water quality criteria in which a Final Acute Value (FAV),
designed to protect 95 percent of a diverse group of species is determined,
and the criteria is established at one half of the FAV. This represents the
only possible approach for many organic compounds, although it is important to
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recognize that for some compounds the lowest concentration causing adverse
effects is based on a very limited toxicological data base, and the derived
sediment criteria may be inadequate to protect aauatic life.
JRB Associates (1984) used the sediment-water equilibrium partitioning
approach to establish tentative sediment criteria for six trace tretals and 47
synthetic organic compounds. The criteria were then compared against observed
concentrations of contaminants in Puget Sound. The criteria values appeared
to be reasonable in that observed contaminant concentrations generally
exceeded criteria only in several urban embayments that historically had
received high inputs of contaminants. Sediments in areas distant from
pollutant point sources had contaminant concentrations generally well below
criteria levels.
Advantages
• The large toxicological data bas» * .
quality criteria i, directly ln
Sediment quality criteria can be develooed'for th* crlE"la"
»Mch EPA water quality criteria .re a°,a,b". expound, for
* Th?,C!;T"JiC't b*!-! of the approach are
well-defined, facilitating verification —j / are ...
of field and laboratory «udiH °" *nd/°r °" th«
Disadvantages
• Mo sediment criteria can be established for those compounds for
which EPA water quality criteria have not been developed (as discussed
above).
? /PP ? ? t L* t f?Vny crease in contaminant
burden of biota which may result from ingestion of contaminated
sediments above that which is attained simply by absorption from the
interstitial/overlying water.
• The assumption of contaminant equilibrium between solid and aaueous
phases inherent in the approach may not always hold in natural svstems
(Prahl and Carpenter, 1983).
• Criteria developed for trace metals have a very high associated
uncertainty, making their regulatory application difficult.
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2.3.2 Sediment-Biota Equilibrium Partitioning
Definition
A sediment quality criterion is established as the concentration of
contaminant in sediment that ensures that it is impossible for an organism at
thermodynamic equilibrium with the sediment to attain a contaminant body
burden in excess of an established permissible limit.
Methodology
This approach, also known as the thermodynamic equilibrium/
bioavailability approach, has been principally advocated by EPA/ERL-
Narragansett and the Corps of Engineers. The most complete discussion of the
methodology involved can be found in Peddicord (unpub.). It should be noted
that this approach has been suggested for use only for the development of
sediment criteria for hydrophobic or neutral organic compounds. Metals,
water-soluble organics, or compounds that associate with sediment principally
by electrostatic interactions are not considered since they do not satisfy the.
requirements of the equilibrium partitioning model.
The sediment-biota equilibrium partitioning approach defines a sediment
criterion on the basis of a permissible tissue level by the equation:
log SQC - (log C* - 0.28) + log TOC (6)
where SQC is the sediment quality criterion;
CX is an acceptable tissue concentration for contaminant x, expressed on
a lipid basis;
0.28 is a factor accounting for the relative activities of hydrophobic or
neutral compounds in TOC and in lipid (origin of 0.28 not given by
Peddicord, unpub.); and
TOC is the total organic carbon content of the sediment expressed as a
fractional mass on a dry weight basis.
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This approach has a number of inherent assumptions. First, all organisms
are considered to have a similar bioaccumulation potential when contaminant
burden is expressed 011 a lipid basis. In other words, all lipids are
considered to have a similar affinity for hydrophobic or neutral organic
compounds. Second, the hydrophobic or neutral organic compounds in organisms
are considered to be predominantly associated with the lipid fraction. Third,
since the activity of hydrophobic or neutral compounds in lipid and TOC are
very similar in comparison to the wide differences in activity between either
of these organic phases and water, the bioaccumulation potential for these
compounds is considered to be compound-independent. The only compound-
specific information required is the permissible tissue concentration, since
the distribution coefficient of the contaminant between sediment and biota is
considered to be a constant.
This approach depends on designating a permissible level of contamination
in tissue from which sediment criteria can be developed. At present, the only
permissible tissue levels available are those employed by the Food and Drug
Administration (FDA), and these criteria are available for only a very few
contaminants. In addition, they have been established only for the protection
df human health and thus may not provide adequate protection against other
environmental impacts. Application of the sediment-biota partitioning
approach therefore depends on developing an extensive burden-effect data base
in order to establish biologically "safe" levels of contaminants in tissue.
The extensive laboratory and/or field testing required to develop this data
base would in many respects be similar to developing sediment criteria
entirely by the bioassay approach (see Section 2.4).
Recognizing the current absence of the burden-effect data needed to
directly determine acceptable contaminant levels in tissue, Peddicord (unpub.)
proposed a method of estimating these levels from water quality criteria. It
is assumed that organisms living in an environment in which EPA water quality
criteria are not violated, would also have acceptable levels of contaminants
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in their tissues. Water quality criteria (WQC), and appropriate bioconcentra-
tion factors (BCF) can therefore be used to estimate the C* term of equation
(6) by:
log C* « log BCF ~ log WOC (7)
While a variety of equations are available to estimate a bioconcentration
factor for a compound from its octanol-water partition coefficient, Peddicord
(unpub.) proposed the use of:
log BCF « 0.980 log KQW - 0.063 (8)
Developing sediment criteria using acceptable tissue contaminant levels
derived from water quality criteria and bioconcentration factors can be shown
to be identical to abiotic partitioning involving only sediment and water (see
Appendix A) and thus does not present a unique approach to developing sediment
criteria. Furthermore, the approach requires the quantification of two
partitioning processes (water-biota and biota-sediment) and thus increases the
opportunity for error.
Advantages
• Permissible tissue contaminant levels developed from burden/effect
studies would result in criteria that account for uptake mechanisms
involving both interstitial water and ingestion of sediment.
• Provides an impetus for burden effect studies that can increase our
understanding of contaminant behavior and bioavailability.
Disadvantages
• Little is known about the variation in bioaccumulation factors with
contaminant type, animal species, or lipid composition.
• Few data are available on acceptable tissue levels for contaminants
present in natural sediments. The FDA levels may have little
relevance to environmental quality.
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• Some organic compounds may accumulate in animal tissues in a non-
equilibrium manner.
• The full development of this approach would require a very
resource-intensive effort.
2.4 BIOASSAY APPROACH
Definition
Dose-response-type relationships are developed by holding test organisms
in sediments containing a known concentration of contaminant(s) and measuring
mortality, sublethal effects or bioconcentration.
Methodology
Sediment bioassays have been employed for many years as a pass/fail test
to evaluate the biological impact potential of contaminated sediments. For
example, any dredged material proposed for dumping into ocean waters must
either meet several exclusionary criteria or be evaluated by a sediment
bioassay (U.S. EPA/COE, 1977). Test organisms are held in the sediment of
concern for a 10-day period, after which the number of dead organisms are
counted. Any statistically significant increase in mortality relative to
controls is considered potentially undesirable. Though this procedure is
suitable for evaluating the environmental hazard of the contaminated material,
its applicability to sediment criteria is limited by the fact that it does not
identify the causative agent(s) of the observed biological effect.
Sediment bioassays could potentially be used to develop sediment aualitv
criteria in a manner analogous to the way aqueous bioassays have been used to
develop EPA water quality criteria. Clean sediments could be spiked with
known amounts of a contaminant in order to derive a dose-response relation-
ship. Such information has been developed for cadmium (R. Swartz, U.S. EPA,
pers. comm.) but is unavailable for other compounds. While bioassays are
probably a necessary component in the sediment criteria development process,
development of sediment criteria entirely by using bioassays would likely be a
long and difficult process. It would be necessary to conduct bioassays on a
wide variety of organisms, representing diverse feeding types, and to use many
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different sediment types exhibiting a range of physical/chemical properties.
A number of methodological differences would also have to be resolved since
the toxicity of a sediment can be dramatically affected by sample collecting
and handling procedures.
Bioassay approaches to sediment criteria are unique in that they provide
the only means currently available to empirically address interactions among
contaminants that influence overall sediment toxicity. The joint toxicity of
mixtures of contaminants may be additive, more than additive (synergistic), or
less than additive (antagonistic). Synergistic interactions are of particular
concern since biological impacts may be caused by a mixture of contaminants
even when each contaminant is below a criterion established on an individual
basis. Bioassays can be used in the empirical assessment of joint action, for
example by (1) establishing dose-response relationships for particular
contaminant mixtures, or (2) as a final test of biological impact potential of
a sediment in which all contaminants are below their individual criteria.
Advantages
• Criteria would account for all possible routes of contaminant uptake.
• The simplicity of the approach and its comparability to the proce-
dures followed in deriving EPA water quality criteria would promote
public acceptance of the sediment criteria*
Disadvantages
• Appropriate standardized techniques would have to be developed for
sediment bioassay# with contaminated sediments. Widely accepted
methodologies for spiking sediments to a specified level of contami-
nation are particularly lacking.
2.5 SUMMARY OP METHODOLOGIES
Most of the approaches for developing sediment criteria discussed in this
report contain hypotheses or assumptions that must be verified before they can
be applied. In addition, even those approaches that employ methods that do
not require extensive verification (e.g., the bioassay approach) must have
standardized techniques and a data base of criteria levels established before
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implementation. However, it is evident that many of the research needs
identified (e.g., sediment bioassays, sorption models, role of sediment
ingestion in contaminant uptake and other types of bioavailability studies,
and methodologies for interstitial water sampling and analysis) are common to
two or more of the criteria approaches. An important conseauence of this is
that it is possible to define research objectives that will concurrently
benefit a number of the approaches, without the need to immediately select a
preferred approach. In addition, studies initiated to verify specific tenets
of the proposed approaches (i.e., effects of sediment ingestion and
bioavailability) will result in information that can b§ used to establish
standardized techniques and a data base for sediment criteria. This strategy,
therefore, eliminates the necessity of selecting an approach prematurely,
based only on very limited data. Instead, the careful definition of research
goals will ensure that the data gathered are amenable to the verification of a
number of approaches. At that time when a sufficient data base is available
to provide the scientific basis for selecting an optimum approach for the
development of sediment criteria, a large proportion of the data should be
relevant regardless of Che approach chosen.
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3. APPLICATION OF SEDIMENT CRITERIA
3.1 DEVELOPMENT OF NPDES PERMITS
The National Pollutant Discharge Elimination System (NPDES) was
established under the Clean Water Act (CVA) to regulate the discharge of
pollutants from point sources (direct and indirect discharge). For each point
source, an NPDES permit is required, which is valid for a period of 5 years
(unless modified or revoked), in order for effluents to be discharged to
waters of the United States. This permit may contain effluent limitations,
compliance schedules, monitoring and reporting requirements, and any other
terms or conditions accessary to protect water quality.
For point-source discharges, broad classes of pollutants are identified
under the CWA, that must be controlled through the NPDES permit program.
Targeted pollutants Include:
• Conventional pollutants, including pH, biochemical oxygen demand,
fecal coliform, suspended solids, and oils and grease
• 65 classes of toxic pollutants pursuant to Section 304(a)
• Additional toxic pollutants identified by the Administrator under
Section 307(a)(1)
• Nonconventlonal pollutants identified in accordance with Section
301(b)(2)(f) (e.g. iron)
• Thermal discharges.
Permits can contain limitations that are technology-based and/or water
quality-based. To date, technology-based standards are promulgated or
proposed for 24 industrial categories. Where promulgated guidelines do not
exist, permit writers must use Best Professional Judgement (BPJ) in developing
discharge limits.
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As more technology-based effluent limits are put into place for point-
source dischargers, attention has been shifted to the use of water-quality-
based permitting as a means to protect water quality. The focus on water-
quality-based permitting stems from the realization that, even with the
achievement of technology-based limits, many streams and rivers throughout the
country are still not meeting water quality standards.
The water-quality-based permitting approach attempts to link the point-
source discharge to its effect on water quality. In the process, pollution
control costs can then be directly related to water quality benefits. In
contrast, technology-based effluent limits are imposed without consideration
of the quality of the receiving water. Water quality standards and maximum
daily waste loads form the basis for the development of effluent limits that
will protect the water quality of the receiving stream. The methodology most
often used to determine effluent limits is a waste load allocation. Waste
load allocations are formulated by using site-specific, computerized
simulation models, which provide a quantitative relationship between pollutant,
loading and receiving water quality.
A major focus of EPA in the coming years is the water-quality-based
permitting of toxic pollutants. The Agency has recently released a national
policy statement outlining a technical approach for assessing and controlling
the discharge of toxic substances to the nation's waters through the NPDES
permit program. In conjunction with the policy statement, EPA has issued a
draft Technical Support Document for water-quality-based toxics control that
discusses the methods used to implement this program.
The complexity of water-quality-based permitting for toxic and
nonconventional pollutants has led EPA to adopt an "integrated" strategy,
incorporating both chemical and biological/toxicological methods. A number of
issues exist, however, that EPA must face in implementing this strategy:
• Lack of experience in applying the results of whole effluent toxicity
testing in the evaluation of instream effects on biota and in the
development of permit limits
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• Limitations in monitoring data: identifying specific contaminants in
effluents and levels of pollutants instream
• Lack of state water quality standards for toxic and nonconventional
pollutants
• Inadequacy of ambient water quality criteria to protect the entire
aquatic system (e.g. the benthos) from adverse effects, and thus for
use as the only factor in developing water-quality-based effluent
limits.
As noted previously, many toxic contaminants are very low in aqueous
solubility and partition to suspended particulates and sediments. Sediment
thus serves as a sink for these chemicals. Long-term, low-level discharge of
contaminants may therefore result in substantial buildup of these compounds in
bottom substrate. In so far as a large number of organisms (including many
commercially important species) spend most of their lives in or on the
sediments, contaminant levels in this compartment may be of equal or greater
importance in establishing NPDES permit limits than are levels in the water
column* Sediment criteria may thus be an essential element in the development,
of a successful NPDES permitting program for toxic contaminants in effluents
from direct and indirect dischargers.
3.2 ISSUANCE OF CWA SECTION 301(h) WAIVERS
The Clean Water Act (CWA) includes provisions under section 301(h) that
allow Publicly Owned Treatment Works (POTWs) to apply for a modified NPDES
permit to discharge effluent receiving less-than-secondary treatment to marine
waters. Section 301(h) provides that the Administrator of the EPA, with the
concurrence of the state, may issue an NPDES permit to a POTW modifying the
Federal secondary treatment requirements for POTW discharges into certain
ocean or estuarine waters. A 301(h) waiver may be issued if the POTW
adequately demonstrates Chat:
• There is an applicable water quality standard specific to the
pollutant for which the modification is requested, which has been
identified under Section 304(a)(6) of this Act.
• Such modified requirements will not interfere with the attainment or
maintenance of water quality that ensures the protection of public
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tracer supplies and the protection and propagation of a balanced
indigenous population of shellfish, fish and wildlife, and that'allou
recreational activities in and on the water. 8
• The applicant has established a system for monitoring the Impact of
such discharge on a representative sample of aquatic biota, to the
greatest extent practicable.
• Such modified requirements will not result in any additional require-
ments on any other point or nonpoint source.
• All applicable pretreatmenc requirements for sources introducing waste
into such treatment works will be enforced.
• To the extent practicable, the applicant has established a schedule of
activities designed to eliminate the entrance of toxic pollutants from
nonindustrial sources into such treatment works.
• There will be no new or substantially increased discharges from the
point source of the pollutant to which the modification applies above
that volume of discharge specified in the permit.
Because of increased dispersion and assimilative capacity in some marine
receiving waters, it is reasoned that reductions in conventional pollutant
discharges may result In little water quality benefit. aequiring limitations
based on secondary treatment could reeult In "creataent for treatment's sake •
particularly If treatment for conventional pollutants does not result In a
significant incidental removal of toxic pollutants. Congress, therefore,
provided for selective exemptions from Umltecions besed on secondary
treatment of POTWs discharging to marine waters.
There is a wide range of national and regional issues affecting
implementation of the 301(h) waiver program. Two of the i
o or cne most important issues
are the need to provide for:
• The protection of estuaries and other sensitive or stressed waters
• site?"™ t<>XlC poUu"nt contro1 and monitoring at each discharge
Most EPA Regions evaiuatlng 301(h) application, have express.* conc.„
about the potential effects of modified discharge, (under »ai,.r fC0I P0TW>
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and other point sources) on stressed estuarine waters. Of particular concern
is the difficulty in defining a stressed vater body, and the need to determine
the presence of a balanced, indigenous population of aquatic species at the
site of discharge. Established sediment criteria would be very useful in
providing a basis for designating stressed waters. As a device for initial
evaluation of estuarine systems, the use of sediment criteria would encourage
greater uniformity in 301(h) decision-making across EPA Regions.
Attempts to control toxic pollutants through implementation of the 301(h)
program have been hindered by the sheer complexity of technical issues sur-
rounding the identification of toxic pollutant sources and the effects of
toxic pollutant discharges on estuarine and marine ecosystems* The toxics
issue is clearly national in scope however, and several EPA Regions have cited
toxics control as a key Issue in the 301(h) program. Currently 301(h) regula-
tions require dry and wet weather 24-hour composite sampling for the priority
pollutants. Future 301(h) monitoring programs may need to be expanded to
contain effective mechanisms (e.g., repeated Influent/effluent/sludge analy-
sis) to detect the presence of additional toxic pollutants not Identified
during initial monitoring.
Interpretation of monitoting data will be difficult in the absence of
criteria for toxic pollutants in estuarine/marine water column and sediments.
Sediment criteria are particularly important in that sediments serve to
integrate contaminant concentrations over time. Sampling bottom substrate
thus eliminates the high degree of temporal variability to which effluent and
water column sampling is subject.
Without the benefit of sediment criteria, POTWs and EPA officials will be
compelled to rely on Best Professional Judgment to analyze the effects of
pollutant discharges on these environments. Also, POTWs and regulators will
have extreme difficulty in ascertaining the existence of causal links between
toxic pollutant discharges and deleterious environmental effects identified
through the biological monitoring program. Without the use of criteria to
establish clearcut attribution, EPA officials may be compelled to choose
between either taking no action or taking drastic action, such as modifying or
rescinding the waiver, to abate the perceived harm.
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3.3 ISSUANCE OF PERMITS UNDER SECTION 404 OF CWA
Section 404 of the CWA establishes a permit system" to control dredged or
fill materials in U.S. waters. This discharge permit program is administered
by the U.S. Army Corps of Engineers (COE) under environmental guidelines
developed by EPA in conjunction with the Secretary of the Army. The guide-
lines for specifying disposal sites for dredged or fill materials (40 CFR 230)
establish a presumption against discharge unless it can be demonstrated that a
discharge will not have.an unacceptable adverse impact on the aquatic ecosys-
tem.
The dredge and fill guidelines apply to discharges of material inside the
baseline from which the territorial sea is measured and to discharges into the
territorial sea. Discharges of dredged material into the territorial seas are
regulated under the Marine Protection, Research, and Sanctuaries Act (MPRSA)»
These guidelines are the primary tool used by the COE to determine whether or
not a proposed disposal activity will have unacceptable adverse effects on
water quality, wetland resources, and biota.
The 404(b) Guidelines address potential Impacts on:
• Physical and chemical characteristics of the aquatic ecosystem
• Biological characteristics of the aquatic ecosystem
• Special aquatic sites
• Human use characteristics.
The guidelines also specify consideration of water-related impacts. A
proposed discharge muse not cause or contribute to violations of applicable
state water quality standards, violate applicable toxic effluent standards or
prohibitions under CWA Section 307, or cause or contribute to significant
degradation of U.S. waters* Currently, EPA water quality criteria for the
protection aquatic life are the major tool used in evaluating water quality
Impacts.
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Sediment criteria are needed Co supplement existing water quality cri-
teria for the evaluation of dredged materials. The current U.S. EPA/COE
(1977) procedures for evaluating dredged material is a pass/fail, solid-phase
sediment bioassay test. However, the test does not identify the causative
agents of observed effects and cannot be used in establishing limits for
contaminants in discharged materials. The criteria are needed to protect
organisms exposed to elevated levels of contaminants in the bottom substrate
and interstitial water, and to determine the significance of these contaminant
concentration.
3.4 OCEAN DISCHARGE/OCEAN DUMPING PERMITTING
EPA is responsible for evaluating all types of ocean dumping under Title
I of the MPRSA. By means of a permit system, the Act prevents or strictly
limits the dumping of materials that would adversely affect human health,
welfare, or amenities, or the marine environment, ecological systems, or
economic potential. EPA is responsible for establishing and revising the
criteria on which permit applications are evaluated. The MPRSA permit system
is administered by EPA with the exception of permits for dredged material
dumping, which are issued by the Secretary of the Army acting through the
Corps of Engineers, pursuant to EPA's criteria.
Specific prohibitions, conditions, and limitations must be met for a
permit to be issued. Certain materials, such as high-level radioactive
wastes, may not be dumped at all. Other constituents are prohibited except
when present as trace contaminants. Toxic wastes are unacceptable for dumping
unless such wastes can be dumped without exceeding applicable marine water
quality criteria or passing a series of bioassay tests. Additional limita-
tions for other harmful constituents must be met. In addition to meeting
environmental impact criteria, applicants must demonstrate a lack of available
alternatives to ocean dumping, and must show that no unacceptable adverse
effects on aesthetic, recreational, or economic values, or on other uses of
the ocean will occur.
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A U.S. EPA/COE joint effort under Section 103 of the MPRSA resulted in
the development of criteria and biological and chemical test procedures with
which to evaluate the acceptability of dredged material for ocean dumping.
The primary intent of Section 103 is to regulate and limit the adverse
ecological effects of ocean dumping. The procedures recommend toxicological
evaluations of the liquid, suspended particulate, and solid phase portions of
the dredged material.
These same procedures are used in evaluating the disposal of dredged
material pursuant to Section 404 of the CWA. As no.ted in the previous section
of this report, there are currently no EPA procedures to determine the
environmental activity of any contaminants or combination of contaminants
present in the solid phase. It is generally felt that if a dredged material
is going to have an environmental impact, the greatest potential for impact is
in the solid phase. Sediment criteria could be a useful scientific tool for
additional evaluation of the solid phase portion of dredged materials and in
predicting the impacts on organisms that live in and on the sediment.
3.5 EVALUATION OF REMEDIAL ALTERNATIVES AT SUPERFUND SITES
Under the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 (CERCLA), a fund (generally referred to as Superfund) is
established for financing the cleanup of uncontrolled hazardous waste sites.
CERCLA also requires that procedures be established to evaluate remedial
actions. Such remedial measures must be, to the extent practicable, in
accordance with the National Contingency Plan (NCP) and must balance the needs
for protection of public health, welfare, and the environment at the facility
under consideration with the availability of monies from the fund to respond
to problems at other sites Chat present or may present a threat to public
health, welfare, or the environment.
The authority and responsibility for carrying out these provisions under
CERCLA has been given to EPA. The plan for carrying out these provisions has
been incorporated in the revised NCP (47 FR 31180, July 16, 1982; 40 CFR 300)
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as Subpart F (40 CFR 300.61-300.71). The NCP sees forth the process by which
remedial actions will be evaluated and selected and the factors that will be
considered in this process.
The NCP requires a detailed investigation of the uncontrolled waste site
in order to obtain the data necessary to define the problem and evaluate
alternative remedial measures. An initial evaluation, or screening, results
in a number of potentially acceptable alternatives that undergo a detailed
evaluation. This detailed analysis includes refinement of the alternatives
in detail, cost estimation, evaluation of engineering implementation and con-
structability, analysis of the extent to which each alternative provides
protection to public health and the environment, and analysis of any adverse
environmental impacts during implementation.
For actions taken pursuant to Sections 104 and 106 of CERCLA (abatement
actions), alternatives must be consistent with all technical requirements of
the following permit programs as a matter of policy.
• National Pollutant Discharge Elimination System (NPDES) requirements
under Section 402 of the Clean Water Act
e Ocean dumping of any material under the Marine Protection, Research,
and Sanctuaries Act (MPRSA) of 1972
e Hazardous waste treatment, storage, and disposal facility requirements
under Subtitle C of the Resource Conservation and Recovery Act (RCRA)
• Underground injection control (U1C) requirements under the Safe
Drinking Water Act
• Requirements under the Clean Air Act
• Polychlorinated Biphenyl (PCB) requirements under Section 6 of the
Toxic Substances Control Act.
The availability of sediment criteria would be helpful both in evaluating the
magnitude of the soil contamination problem at uncontrolled waste sites and in
assessing remedial alternatives that require off-site disposal. In particu-
lar, sediment criteria may form the basis for evaluating remedial actions that
call for discharge of hazardous waste, in the form of contaminated soils, to
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freshwater, estuarine, or marine systems, and that require permits under the
CWA (NPDES) or the KPRSA.
3.6 IDENTIFYING HAZARDOUS WASTE UNDER RCRA
Subtitle C of the Resource Conservation and Recovery Act (RCRA) requires
EPA to promulgate regulations establishing a Federal hazardous waste manage-
ment system. Under Section 3001 of Subtitle C, EPA is required to identify
the characteristics of, and to list those solid wastes that must be managed as
hazardous waste undisr the established system.
As specified in Section 261.11 of RCRA, a waste is listed (by the
Administrator of EPA) as a hazardous waste if it meets one of the following
criteria: (1) it exhibits any of the characteristics identified in Subpart C,
i.e., ignitability, corrosivity, reactivity, EP (extraction procedure)
toxicity; (2) it is designated as.an "acute hazardous waste", i.e., oral
(rat) < 50 mg/kg, inhalation LC^q (rat) < 2 mg/1, or dermal (rabbit)
< 200 mg/kg; (3) it contains any of the toxic constituents listed in Appendix
VIII (unless shown, according to criteria specified in 261.11(a)(3), not to
present a hazard to human health). Note that these are the criteria by which
a waste is listed as a hazardous waste. A generator of solid waste on the
other hand, is required to declare a waste as hazardous under RCRA, if:
(1) it is listed in Subpart D Appendix VII; (2) is a mixture containing a
hazardous waste listed in Subpart D; and/or (3) it exhibits any of the
characteristics identified in Subpart C (as above). A generator is not
required to declare a waste hazardous solely because it contains an Appendix
VIII constituent. Appendix VIII in this case, is for information purposes
only and has no independent regulatory force.
A major issue concerning the implementation of RCRA regulations, is the
absence of the use of "quantity" to define hazardous waste, i.e., in deter-
mining levels for each waste or toxic constituent (when improperly managed)
below which it does not pose a substantial hazard to human health and the
environment. To date, the EPA has not been able to find a satisfactory way
of determining "de minimis" quantities. Extraction Procedure (EP) toxicity
testing establishes limits only for 14 compounds and these limits are for
levels in extract, not in the waste itself.
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The availability of sediment criteria would be an important factor in
enabling EPA to establish threshold quantities for defining a waste hazardous.
As pointed out by EPA, determining threshold levels requires a Knowledge not
only of intrinsic properties of the waste under consideration, but also of
site-specific conditions and the possible management scenarios. However, when
Che issue is disposal of contaminated sediments (e.g. in landfill), sediment
criteria could be appropriately used. These criteria may also be valuable in
evaluating, or developing methods for evaluating the hazardous nature of
contaminated soils.
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4. REFERENCES
Adams, W.J., R»A. Kimerle, and R.G. Mosher. 1983. Aquatic safety assessment
of chemicals sorbed to sediments. Paper presented at ASTM Seventh Annual
Aquatic Toxicology Synposium April 17-19, 1983, Milwaukee, HI.
Chapman, G.A. 1984. A review of procedures for evaluating the biological
significance of sediment contamination and establishing sediment
criteria. Internal EPA document prepared for the Office of Criteria and
Standards by the Corvallis Environmental Research Laboratory.
FowleT;7I*W,'DG;G\f0likarp°V:jD'L- Elder' p- P«si, and J.P. Villeneauve.
1978. Polychlorinated biphenyls: accumulation from contaminated
Water by the P°lychaete Nereis diversicolor. Mar. Biol.
48:303-309. —
Hansch, C., and A.J. Leo. 1979. Substituent Constants for Correlation
Analysis in Chemistry and Biology. John Wiley, New York.
JRB Associates. 1984. Initial evaluation of alternatives for development of
sediment related criteria for toxic contaminants in marine wate^ (Puget
Sound). Phase II. Development and testing of the sediment-water
equilibrium partitioning approach. Prepared for the U.S. Environmental
Protection Agency, Office of Criteria and Standards by JRB Associates,
Bellevue, WA, under EPA Contract No. 68-01-6388. 89 pp.
Karlckhoff, S.W., D.S. Brown, and J. A. Scott. 1979. Sorption of hyrophoblc
pollutants on natural sediments. Water Research 13:241-248.
Lyman ».J. W.F. Re.hl, »i U. Rosenblatt. 1982. Handbook of Chemical
Property Estimation Method,. Environmental Behavior of Organic
Compounds. McGraw-Hill Book Co., New York.
Pavlou, S.P. and D.P. W«ton. 1983. Initial evaluation of alternatives for
development of sedl-nt related criteria for to«ic contaminant, in marine
water (Paget Sound). Phase Is Development of conceptual framework.
Prepered for the D.S. Environmental Prot.ctlon Agency, Office of Criteria
* A"oclac"' Bellevue, WA, under EPA Contract No.
0O-01-OJOO»
Peddicord, R. Unpublished manserp. Scientifically defensible development and
implementation of sediment quality criteria. Internal document prepared
for the U.S. Environmental Protection Agency, Office of Criteria and
wtdndflrds•
Prahl F.G., and R. Carpenter. 1983. Polycyclic aromatic hydrocarbon
(PAH)-phase associations in Washington coastal sediment. Geochimica et
Cosmochimica Acta. 47:1013-1023.
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U.S. EPA/COE. 1977. Ecological evaluation of proposed discharge of dredged
material into ocean waters. U.S. Army Waterways Exper. Sta., Vicksburg,
MS.
U.S. EPA/WDOE. 1984. Interim decision criteria for disposal of dredged
material at the Four-Mile Rock open-water disposal site. Prepared by
EPA-Region X and the Washington Dept. of Ecology.
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APPENDIX A
The sediment biota equilibrium partitioning approach to sediment criteria
(Section 2.3.2) attempts to define a concentration of a contaminant in
sediment such that levels of this pollutant in the tissues of an organism at
equilibrium with that sediment cannot exceed some predetermined acceptable
level. Ultimately it is expected that these acceptable tissue levels will be
determined by burden-effect studies. Peddicord (unpub.) has suggested
however, that on an interim basis, these tissue levels could be estimated from
water quality criteria and bioconcentration factors. It is shown belows that
this approach is conceptually identical to the sediment-water partitioning
approach (Section 2.3.1).
At equilibrium the concentrations of a contaminant in the various
reservoirs (sediment, biota, and water) can be described using the following
equations:
^ ^
*W * CB/CW (2)
KB " Vcs (3)
where K equals the distribution coefficient and Cg, Cw, and CB equal contami-
nant concentrations in sediment, water, and biota, respectively.
In the sediment-water equilibrium partitioning approach (see Section
2.3.1), equation (1) is rearranged to yield:
logfCg] - loglKpI ~ log[cw] (4)
Sediment criteria for contaminant concentrations can be calculated using this
equation if values of and Cy are available.
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In the sediment-biota equilibrium approach (see Section 2.3.2),
rearrangement of equation (3) yields:
log[Cg] - log[CB] - 1og[Kg]
(5)
Because of the sparsity or uncertain nature of data concerning acceptable
concentration levels of contaminants in animal tissue, Peddicord (unpub.) has
proposed that EPA water quality criteria be used to calculate acceptable
tissue levels. Rearrangement of equation (2) results in:
which can be used to calculate acceptable tissue levels. Substitution of this
equation into equation (5), which defines sediment criteria on the basis of
tissue levels, yields:
Inspection of equations (2) and (3) shows that this equation can be simplified
to:
which is identical to the equation used to determine sediment criteria in the
sediment-water equilibrium partitioning approach. However, while the
application of the sediment-water approach requires the determination of one
distribution coefficient, K^, the determination of sediment criteria by the
approach outlined by Peddicord (unpub.) requires the knowledge of two
distribution coefficients, and K^, and thus has a greater potential for
error.
To test whether the two approaches would yield similar sediment criteria,
calculations employing both approaches have been made (Table A-l). As can be
seen, the criteria calculated by these equations are very similar despite the
differences in the approaches used to derive the equations.
log[CB] - logfl^] + Jog[Cw]
(6)
(7>
log(Csl - log[Cw] + logtKjj]
(8)
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TABLE A-l
COMPARISON OF SEDIMENT CRITERIA DERIVED BY THE
SEDIMENT-WATER AND SEDIMENT-BIOTA PARTITIONING APPROACHES
Sediment Criteria
(ug/kg-oc)
Approach
Sediment-Water Partitioning3
DDT
158
Endrin
174
Sediment-Biota Partitioning
b
329
321
DDT-Water Quality Criteria (saltwat.r, chronic) - 0.001 ug/1;
log Kqv - 5.98
Endrln-Water Quality Criteria chrMU) , 0.0023 n
log Kgy *3.0 ®
alog(SQC) - log(WQC) ~ 0.843 l„g ^ «. (fr(J„ JR, 1984)
blog(SQC) Sr * «•*« ««. feddicord, unpub..
with adjustments for units)
A-3
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