United Statee
Environmental Prou.rtion Agency
Office of Water &
Office of Reeearch and
Development
Office of Science and Technology
Health and Ecological Criteria Oiv.
Washington. O.C. 20460
EPA-822-R-93-O17
September 1993
Guidelines for  Deriving
Site-Specific Sediment
Quality  Criteria for the
Protection
of Benthic Organisms
                             Printed on Recycled Paper

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  GUIDELINES FOR DERIVING

   SITE-SPECIFIC SEDIMENT

 QUALITY CRITERIA FOR THE

   PROTECTION OF BENTfflC

          ORGANISMS
 (Office of Science and Technology
Office of Research and Development)
                              ... «vv'.ion Agency
                      US. Envirc-T'" ••- - _.; y, ,
                      F:c:s>^ ;;y-:, .:;4>ic"a,d, 12th Floor
                      77 West f;:^;::c:;4:3390
                      Chicago, 11. w^ +

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                            PURPOSE AND APPLICATION
       The purpose of the "Guidelines for Deriving Site-Specific Sediment Quality Criteria
 (SQC) for the Protection of Benthic Organisms" is to provide guidance for the development
 of sediment quality criteria for nomonic organic chemicals which reflect local environmental
 conditions. These site-specific  criteria may be utilized as a part of the basis for establishing
 site-specific sediment quality standards to protect the uses of a specific water body.  These
 guidelines should be used only after understanding the National Water Quality Criteria
 (WQC) Guidelines (Stephan et al., 1985), response to public comment (U.S. EPA, 1985),
 Site-Specific WQC Guidelines (U.S. EPA, 1983), National SQC Guidelines (U.S. EPA,
 1993a), the SQC Technical Support Document (U.S. EPA, 1993b) and SQC documents for
 the chemical of concern.

       The sediment quality criteria have been developed specifically for use in the 304(a)
 criteria program. It is  most appropriate that the need for a site-specific modification to a
 sediment quality criteria be evaluated during the development or updating of a States water
 quality standards. Application of a site-specific modification at the standards development
 stage helps alleviate both the burden on the permit writer to research and write permit
 modifications by permittees as a means to avoid strict effluent limitations.

       The Office of Water recognizes, and has encouraged, that the criteria will be  used by
 many other programs.  The appropriate used of the site-specific modification procedures in
 these programs should be obtained from the implementation guidance developed by that
 program for inclusion in the "Guide for the Use and Application of Sediment Quality Criteria
 for Nonionic Organic Chemicals".  (U.S. EPA, 1993b)

 Rationale  for the Development of Site-Specific Criteria

       National sediment quality criteria guidance may be under or over protective if: (1) the
 species at the site are more or less sensitive than those included in the national criteria data
 set or (2)  the sediment or chemical quality characteristics at that site alter the bioavailability
 consequently the toxicity of the sediment bound chemical predicted by Equilibrium
 Partitioning (EqP). Therefore, it is appropriate that site-specific guidelines procedures
 address each of these conditions separately, as well as jointly.

       Site-specific criteria development is justified because species at a site may be more or
less sensitive than those in the national document.  For example, the national criteria data set
may contain data for salmonids, daphnids, penaeids  or mysids, families that have been shown
to be especially sensitive to some chemicals.  Since these, or other sensitive taxa,  may not
 occur at a particular site, their sensitivities may not be representative of the sensitivities of
those species that do occur there or at a similar non-degraded site.  Conversely, untested
uniquely sensitive species that are ecologically or economically important which need to be

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protected may exist at the site.  The "Deletion/Substitution Procedure" described in this
document is intended to be used to modify national SQC to account for these differences in
species sensitivity.

      Although a variety of sediments have been tested to ensure the EqP approach is
applicable to a wide array of sediments, sites may possibly exist where EqP theory does not
accurately predict the bioavailability and toxicity of contaminants in the sediments.  Unique
sediment characteristics, chemical speciation, or chemical form may make the criteria
chemical more or less bioavailable thereby altering the toxicity of the sediment. For
example, in some sediments PAHs are known to occur as particulates not partitioned to
organic carbon.  The "Bioavailability Procedure" described in this document is intended to be
used to modify national SQC to account for these differences in bioavailability.

      Finally, differences in species sensitivity and chemical bioavailability at a specific site
may, in combination, make derivation of a more appropriate site-specific SQC desirable.
For these reasons, EPA provides guidance for the derivation of site-specific SQC. The
"Empirical Derivation Procedure" described in this document is intended to be used to
modify national SQC to account for both of these differences.

      If the sediments are toxic, the national SQC  apply and site-specific criteria
modifications are not permitted.  If sediments are toxic,  sediment Toxicity Identification
Evaluations (Ankley et al., Draft) are recommended to attempt to identify chemicals causing
observed effects.

Definition of Site:

      The rationales for site-specific guidelines are based on either (1) potential differences
in sensitivity of species resident at a site relative to  those used to derive the national SQC;
(2) potential differences in the characteristics of sediment or the chemical at the site that alter
biological availability; or (3) a combination of these differences.  The concept of site mustfbe
consistent with these rationales.  Therefore, the definition of site is different for species
sensitivity and biological availability.

      Derivation of a site-specific SQC based on species sensitivity differences requires
that resident species that occur at the site be identified.  Because species that occur at the  site
includes pertinent, seasonal, intermittent and those species excluded because of anthropogenic
causes, the spatial and temporal extent of the site must be large.  Therefore,  the definition
site must be broad enough to include the immediate site  of concern over time, other similar
unimpacted or impacted sites and may include entire biogeographic providences.  If the
sediment is to be moved, the species at the site where sediments will be placed should be
included as site-species.

      Derivation of a site-specific SQC based on bioavailability differences requires that  the
site be narrowly defined to include the spatial extent of the site, where SQC are exceeded or

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 unique site-specific characteristics of the sediment or the chemicals form are believed to
 violate assumptions of biological availability that are fundamental to equilibrium partioning-
 based SQC.  Therefore, the spatial extent of the site as applied to the Bioavailability
 Approach only includes the area containing sediments that are believed to be unique from a
 chemical availability perspective.

       Derivation of a site-specific SQC based on the Empirical Derivation Approach
 requires a definition of site that is appropriately a mix of that used in the preceding two
 approaches.  Selection of resident species for testing should use the same definition of site as
 the Deletion/Substitution Approach.  Sediments to be tested should be selected from the site
 as defined by the Bioavailability Approach. Resultant site-specific SQC apply only to the site
 defined by the Bioavailability Approach.
Goals of Site-Specific Criteria Modification:

       The goal of this document is to describe procedures which can be used to modify
national SQC values. The procedures are similar to those recommended for use in
modification of national water quality criteria values (U.S. EPA, 1983).  They include
(Figure 1): (1) a Resident Species Deletion/Substitution Procedure to adjust SQC for
sensitivity of species found at the site; (2) a Bioavailability Procedure to derive a sediment
effects ratio to adjust national SQC to account for site-specific differences in bioavailability;
and (3) an Empirical Derivation Procedure to experimentally derive site specific SQC using
toxicity tests with site sediments and resident benthic species (Figure 1).  It is  EPA's intent
that modification of the national SQC will rarely  be needed. Therefore, preliminary site
specific evaluations are recommended prior to initiation of these site-specific modification
procedures.  For example, examination of sensitivities of major taxa related to a resident
species list must occur prior to selecting species for substitution tests.  In addition, it may be
informative to conduct range-finding site sediment spiking tests prior to beginning definitive
bioavailability testing.

       Numerous efforts to conduct site-specific water quality criteria modifications have
demonstrated that site-specific experimental designs and QA/QC concerns in the conduct of
the tests,  not the theoretical basis of the site-specific modification or required  procedures,
have caused failures to justify the need for site-specific water quality criteria (Brungs,  1991).
Therefore, we strongly recommend that users of these guidelines for developing site-specific
SQC consult early on and closely  with the U.S. EPA Offices of Science and Technology,
Research and Development and appropriate Regional Office in the design and conduct  of
these procedures.  [Specific individual to contact will be listed here in the final document.]

     PROCEDURES FOR CONDUCTING SITE-SPECIFIC SOC MODIFICATIONS!

Resident Species Deletion/Substitution Procedure:

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Figure 1. Flow chart of approach for deriving site speciflc sediment quality criteria.
                                          Site-Specific Sediment Quality
                                        Criteria  Modification Procedures
     Resident Species Deletion /
     Substitution Procedure: (Goal: Adjust
     SQC for sensitivity of benthic species
     from the she or their surrogates.)
                 Bio*variability Procedure: (Ooal:
                 Derive Predicted Sediment Toxic
                 Unit (PSTU) to adjust SQC for she-
                 specific difference in biological availability)
                 PSTU-She Sediment LCSO ug chemical / gOc
                 /LCSOtHOxKoc.
                                       Empirical Derivation Procedure: (Goal me
                                       lite sediment md specks to account for
                                       biological availability of rite aedimenti
                                       and the aenritivity of rite species to chemicals
                                       in thete sediments.) (TVro approaches.)
         Spccia Deletion
               I
Use national SQC
consider TIE'S
                      toxic
She Sediment
Acceptability Test
                               non-toxic
         Species Substitution
               I
    Recalculation of Final Acute Value
    for resident benthk species. Derive
    SS SQC as (FAV / Final ACR from national
    SQC document) xKoc
                          Water only lethality test
                          LCSO (ug/L) x Koc - Predicted
                          sediment LCSO ug chemical / gOc.
                                                                                                                               I
                                             SS SQC - SS SQC derived using
                                             the Resident Species Procedure x PSTU from the
                                             Unavailability Procedure
                          Sp*ed She Sediment
                          lethality test-Measured
                          LCSO ug chemical /gOc.
                                                             omplete minimum acute
                                                             entsforbenthic
                                                                                  species tested in rite sediments:
                                                                                  LCSO «4 chemical / gOc (Note:
                                                                                  This option can not be used until
                                                                   PSTU - Measured sediment LCSO/
                                                                   Predicted sediment LCSO
                                                                               SS SQC-FAV from above tests/
                                                                               final ACR from national SQC document
                                                                               or ACR from chronic she sediment test
                                        If PSTU not
                                        different from I 0
                                        use national SQC
                                                                      If PSTU significantly > or < t.O
                                                                      and does not differ across
                                                                      site sediments: SSSQC-
                                                                      national SQC x mean PSTU
                                                                       If PSTU differs
                                                                       across sediments use
                                                                       national SQC unless
                                                                       of variation is known.

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       Description:

       This deletion/substitution procedure is intended to result in a site-specific SQC that
appropriately differs from the national SQC when there are pertinent differences in the
sensitivities of benthic organisms that occur at the site and those used to derive the national
SQC concentration. This procedure follows that of the WQC recalculation procedure
discussed in "The Determination and Use of Water-Effect Ratios for Metals" (Stephan et al.,
Draft.)

       Rationale:

       This approach may be relevant because: (1) SQC are intended to protect benthic
organisms so acute values for water column species or water column life-stages of species
that also have benthic life stages may not be relevant to SQC derivation unless they are
lexicological surrogates for taxonomically related untested resident benthic species or life-
stages.  (2) Sensitive or insensitive benthic species used to derive the national SQC may not
occur at the site.  (3) The species that occur at the site might be taxonomically  limited
because of the limited range of environmental conditions at the site.

       For the purposes of these site-specific guidelines, resident organisms "that occur at
the site" is defined as those benthic species, genera, families, orders, classes or phyla of
organisms that periodically or commonly occur at the site.  (See previous definition of site.)
This includes organisms that occur continually, seasonally, intermittently and those that are
now absent because of anthropogenic causes. Organisms absent because of physical changes
such as impoundment of rivers are  not considered resident.  This will require use of historical
species lists for the site and use  of biological assessment databases from nearby reference
sites.

       Deletion begins at the life-stage and species level, proceeds through higher taxonomic
levels and considers the need for acute values from test with nonresident benthic species or
water column lifestages of benthic species to be lexicological surrogates for taxonomically
related but untested resident benthic species.  Testing with, resident benthic species is
required to complete minimum database requirements for deriving criteria, to obtain data on
endangered or threatened  species or their surrogates and to provide data when it is desirable
to replace acute values for water column or nonresident species that  serve as surrogates for
untested resident species.

       Use of this procedure may increase, decrease or fail to change the national criteria.
If highly sensitive species are  not present at the site an increase in the criterion  is likely.  If
the number of acute values in decreased the criterion will likely decrease. Additional testing
may reveal uniquely sensitive  or resistant species that could lower or raise the criterion.
Because water column and benthic species have similar sensitivities (Di Toro et al., 1991),
deletion of acute values for water column species or lifestages and replacement  with newly
obtained data on benthic organisms would seem likely to not markedly alter the criterion.

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              of the Resident Species Deletion/Substitution Procedure:

       The basic principals of the deletion substitution option are:

       1.  A literature search must be conducted so that all available acceptable data
approved by EPA that are not in the SQC document Appendix A are used to recalculate the
Final Acute and Final Chronic Values.
       2.  In all cases, deletion and substitution decisions must apply to the entire database
not just sensitive species.
       3.  If data are not available for a rare or endangered species that occurs at the site,
data must be available or generated for an acceptable surrogate species.  (See Stephan et al.,
(1985) for details on test requirements.)
       4.  All acute values for benthic life-stages of resident species must be retained in the
database.
       5.  It is only appropriate to delete acute values for water column lifestages of resident
species if data on the sensitivity of benthic lifestages for that species exist or are produced.
Further, acute values for water column species with no benthic life-stag*!  can only be deleted
if its' sensitivity is not a surrogate or co-surrogate (defined later) for taxonomically related
benthic species.  Water column life-stages of that species  or related species until data are
available on benthic life-stage sensitivity.
       6.  It is appropriate to delete acute values for benthic or water column life-stages of
non-resident species if they are not surrogates or co- surrogates for benthic life-stages of
resident species.
       7.  If a non-resident species is the only tested representative of a genus, family or
higher taxon that is resident, deletion is not permitted  unless a resident benthic species from
that taxon is tested.
       8.  If one or more resident species in a genus,  family or higher taxon have not been
tested, data from non-resident species can not be deleted, even if data exist for resident
species, because data for non-resident and resident species are viewed as  co-surrogates for
untested resident species.
       9.  Therefore, the following data can be deleted: (a) Acute values from tests with
water column life-stages of resident species, providing acute values for benthic life-stages of
that species are known or obtained,  (b) Acute values  for non-resident species when resident
species from the same genus, family or higher taxon do not occur at the site,  (c) Acute
values for non-resident species when all other species  in that genus or higher taxon have been
tested, (d) Acute values can be obtained on benthic life stages of resident species to permit
deletion of data on water column life-stages and on benthic life-stages of  all non-resident
species in a particular genus or higher taxon to eliminate need for data on non-resident to
serve as a surrogate or co-surrogate for untested resident benthic species.

       Derivation of the Site-Specific SOC:

       1.  Following the deletion substitution process  steps for data analysis in Stephan et al.
(1985) must be followed.  Species Mean Acute Values (SMAV) and Genus Mean  Acute

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Values (GMAV) must be calculated . If minimum database requirements are met, except
those that require water column species, a site-specific FAV is calculated. If an acute value
for an endangered, threatened, commercially, recreationally or ecollogically important
species is lower than the FAV, this value becomes the FAV. Finally, the FAV is divided by
the Final Acute Chronic Ratio (FACR) from the SQC document to derive the site-specific
Final Chronic Value (FCV).
      2.  The site-specific SQC is the product of the site-specific FCV and the KOC from the
SQC document.
      3.  Use this SQC and the procedures in Section 5 of the SQC document to derive the
95% confidence intervals.
      4.  All steps in the derivation of a site-specific SQC must be documented in a report
including: A table listing all species and their life-stages used to derive SMAVs, all species
and lifestages deleted, test conditions SMAV, GMAV and references for source of acute
values. This table should be similar to Appendix A in the SQC documents.  The new
calculated FAV, FACR, FCV SQC should appear after the tabular presentation of toxicity
data. All resident commercially, recreationally and ecologically important, and threatened or
endangered species must be listed to permit comparisons between their sensitivities and the
FAV or FCV.  All other species known to be resident to the site and the source of this
information must also be listed.

              Site-Specific SQC = (Site-Specific FCV)Koc

Bjoavaflab; ffify Procedure:

      Description:

      EPA sediment quality criteria for nonionic organic chemicals are based on the EqP
model.  It is possible that sediments may exist for which the EqP model for SQC may not
apply.  In this case, the toxicity of the sediment cannot be predicted from the water only tests
and the K^ because, in addition to organic carbon, other properties of the site sediments
may alter bioavailabilty.  For these sediments, site-specific criteria modification using the
Unavailability Procedure is warranted. The Bioavailability Procedure is analogous to the
"Indicator Species" procedure employed for modifying national WQC for site-specific
differences in bioavailability (U.S. EPA,  1983).  The Bioavailability Procedure presented
below employs a sediment effects ratio (Predicted Sediment Toxic Unit, PSTU) derived as
the ratio of the EqP predicted effects concentration and the actual effects concentration from
sediment toxicity tests using spiked sediments from the site. If the ratio is significantly
different from the PSTU values used to derive the uncertainty of the SQC and uniform across
sediments from the site , the site- specific SQC is the product of the national SQC value and
the PSTU.  It is important to note that the method may lower site-specific SQC because the
sediment spiking tests required may measure interactions from other chemicals present in
sediments from the site.

      Details of the Bioavailabilitv Procedure:

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      This method requires an initial sediment acceptability test, a flow-through measured
water-only lethality test lasting at least 10 days and spiked-sediment lethality tests of the
same duration using a minimum of three sediments from the site. These tests should be
similar to tests employed in chemical-specific verification of the EqP prediction described in
the sediment quality criteria documents.  (See EPA criteria document Section 4, table 4-1,
table 4-2, figure 4-2,  Appendix C and references to these data as cited in the SQC
document.)  An acute sediment lethality test is selected which is appropriate for the water
type (fresh or marine water), sediment type (sandy, muddy) and species  sensitivity to the
chemical.  Table 1 lists the species tested in SQC documents, other appropriate tests and the
references for the experimental procedures. Standardized biological tests using benthic
species that have durations £  10 days are prefered.  Species selected for site-specific testing
using the Bioavailability Procedure must,  if possible, be selected from the list of benthic taxa
demonstrated to be most sensitive to the chemical of concern even if they are not resident to
the site or listed in Table 1. (See Table 3-1 or Appendix A of SQC documents.)

      A minimum of 3 sediments that exceed the SQC, or that are believed to be chemically
or physically unique,  from the site should be selected for testing. If the size of the she is
large, additional sediments may be required to span the range of physical/chemical sediment
conditions.  Procedures for sediment collection and storage required by ASTM (1992a)
should be followed.

      The first step in beginning the use of this site-specific modification method is to
determine the acceptability of  the sediments to the species to be tested.  Survival of the
selected species for the duration of the experiment must exceed 80% unless otherwise
specified in specific methodologies. This procedure requires exposure of the test organism to
sediments from each of three or more sites for a minimum of 10-days or the duration of the
water-only and sediment tests  described below.  Use of acceptable sediments in tests in  parts
2 and 3 should insure that these tests are completed successfully.

      Secondly, conduct water-only toxicity tests with the species to be used in the sediment
tests to determine, at a  minimum, a 10-day LC50 using flow-through procedures in which
tested concentrations are measured (ASTM, 1989). Compute the predicted  10-day LC50 on
an organic carbon basis as the LCSO^o x KQC = LCSO^oc and 95% confidence limits;
using the KQC from the SQC document.

      Third, conduct sediment toxicity tests to determine sediment-specific 10 day LC50
values for the species tested in water-only experiments.

      The experimental design for the series of sediment toxicity tests follows:

       - Select sediment concentrations on an organic carbon basis to bracket the predicted
       sediment LC50. Generally, dilutions should be no greater than 0.5 log,0 units
       with three treatments above and two below the predicted sediment LC50.  For
       example, if the predicted LCSO is 8.4 pg/goc> treatments might be control 1.0, 3.2,

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Table 1. - Toxicity tests that can be used to modify national sediment quality criteria using the Bioavailability or Emperical Derivation
Procedures. (I = Infaunal; E = Epibenthic; CV  = Chronic Value)

Organism

Polychaetes
Neanthcs arenaceodentata
N H
Amphipods
Ampelisca abdita
H n
Eohaustorius estuarius
Grandidierella japonica
Leptocheirus plumulosus
N H
Rhepoxynius abronius

Amphipods
Hyalella azteca
H H
Insects
Chironomus tentans
H N
Chironomus riparius
N n

Habitat


I
I

E
E







E
E

E
E
E
E

Test


Acute
Life-cycle

Acute
Life-cycle
Acute
Acute
Acute
Life-cycle
Acute


Acute
Life-cycle

Acute
Life-cycle
Acute
Life-cycle

Endpoint


LC50
CV

LC50
CV
LC50
LC50
LC50
CV
LC50


LC50
CV

LC50
CV
LC50
CV
Days
Duration
Saltwater

10
ISO

10
56
10
10
10
?
10
Freshwater

10
30

10
25
10
30
References
Method SQC Method


Peschetal., 1991
Peschetal., 1991

ASTM, 1992b DiToro, 1990
Scott and Redmond, 1989
ASTM, 1992b Swartz, 1991
ASTM, 1992b
ASTM, 1992b Swartz, 1991
? , -
ASTM, 19925 Swartz et al., 1990


ASTM, 1992c Hoke and Ankley, 1991
ASTM, 1992c

ASTM, 1992c Hoke and Ankley, 1992
ASTM, 1992c
ASTM, 1992c
ASTM, 1992c

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                                                                                   10

             10, 32 and 100 /tg/goc- Range finding experiments may be desirable for
             selecting test concentrations, if EqP predicted bioavailability proves to be
             incorrect.

             - For each of the three or more site-sediments tested there should be a control
             and a minimum of five spited sediment treatments.  Sediments should be
             spiked a minimum of 2 weeks before initiation of the spiked sediment toxicity
             test. Methods  for chemical spiking have been recommended by ASTM
             (1992a), Environment Canada (1993) and U.S. EPA (19935).  For chemicals
             with high partition coefficients, chemical analyses to demonstrate stability of
             pore water concentrations or toxicity tests to demonstrate constancy of
             response may be required.

             - Each treatment should contain 3 biology replicates and 2 replicates for
             chemical determination.

             • Control survival in biology replicates must be greater than 80 percent unless
             otherwise stated in specific methodologies.

             - Chemistry replicates are sampled for interstitial water chemical and DOC,
             and sediments for TOC and total chemical concentrations; the first replicate is
             sampled on day 0 and the second at test termination (day 10).   The day 10
             chemical replicate must contain the tested organism.  Interstitial water is
             sampled by centrifugation using the method of Edmunds and Bath  (1976).
             Freely dissolved chemical concentrations in interstitial should be quantified
             using the method of Landrum a al., 1984. If the EqP-based SQC are
             applicable to site-sediments, interstitial measurements are not necessary.
             However, they are essential if partitioning is not as predicted by the KQC from
             the SQC document.

             - A statistical test is employed to determine if the three site LCSOs are
             statistically different from the prediction using EqP. The prediction is
             calculated as follows.  For each sediment the predicted sediment toxic unit
             concentration (PSTU) is calculated:

                             PSTU - LCSO^oc / (Koc X LCSO^ )

Where LCSO^oc is the site sediment LC50 on an organic carbon basis, KQC is the organic
carbon partition coefficient from the sediment quality criteria document, and LC50,Qo is the
water only LC50.  The EqP model predicts that PSTU = 1 within the EqP model uncertainty
for each site sediment.  A statistical test is employed to test whether the PSTUs for each
sediment are statistically different from the uncertainties of the PSTU prediction  in the
national SQC document (Table 2). The statistical analysis should incorporate variability in
PSTU values from site-specific sediment tests and variability inherent in sediment tests used

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                                                                                    11

to calculate the uncertainty of SQC values. If they are not statistically different, the EPA
national criteria are used without modification.

       If they are statistically different, then the geometric mean of the PSTU values is
computed and it is used as the Site Sediment Effects Ratio.

       A two sample t-test is used to determine if the "site" PSTU's come from the same
population as the "database"  PSTU's.  First the PSTU's are log normalized.  (The
distribution of the logs of the 32 PSTU's (Table 2) in the existing database was not
significantly different from normal; SAS, Proc Univariate.) An F-max test (Sokal and Rohlf,
1981) can be used to test if the variances of the "database* and "site" PSTU's are
significantly different. If the variances of the "database" and "site" log PSTU's are not
significantly different the means of the log PSTU's can be compared using the following
formula:
                    t =
                               Sp(l/nd+l/n,)v4

       Where:
              t   as t value of the difference between the means
              Xj =  mean of the log "database" PSTU's
              x, =  mean of the log "site" PSTU's
              Sp =  pooled variance of the "database" and "site" PSTU's
              n,, =  number of "database" PSTU's
              n, =  number of "site" PSTU's

       If the variances are significantly different, an approximate t-test can be used (Sokal
and Rohlf,  1981).  A two-sided test is appropriate because it is being used to determine if
there is a greater or lesser difference between the mean of the "database" PSTU's and the
mean of the "site" PSTU's.

       Derivation of the Site-Specific SOC:

       Following completion of acceptable toxicity tests demonstrating a PSTU greater or
less than PSTU values used to derive the uncertainty of the national SQC concentration, the
site-specific SQC can be derived:

                    Site-Specific SQC  = National SQC X Mean PSTU

       If the PSTU is significantly different from one, then the chemical in site sediments is
less bioavailable than is predicted by EqP, and the national SQC is appropriately increased.
This would be the case if, the organic carbon is more sorptive than the KQC used, there are

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              TABLE 2:  PREDICTED SEDIMENT TOXIC UNITS  (PSTU)'
(Note:  For additional  information see Sediment Quality Criteria Documents.)


Chemical



Acenaphthene


Common/Sci
Name


Amphipod,


Method4
Duration
(davs)

FT,M/10
Eohaustorius estuarius
n
Amphipod,
FT,M/10


Sediment
TOC

(%)
1.23
0.82
2.49
Hater
Only
LC50


/ig/L
374

374


KOC


L/Kgoc
3.78

3.78
Sediment
Measured



A«9/9oc
4,330

1,920
LC50
Predicted"



M9/9oc
2,250

2,250

Ratio:
Measured/
Predicted
(PSTU)'

1.92

0.85


Reference



Swartz, 1991

Swartz,1991
Eohaustorius estuarius
n
Amphipod,
FT,M/10
4.21
374
3.78
1,630
2,250
0.72
Swart z, 1991
Eohaustorius estuarius
n
Amphipod,
FT,M/10
Leptocheirus plumulosus
n
Amphipod,
FT,M/10
1.62
0.82
2.52
678

678
3.78

3.78
>23,500

7,730
4,080

4,080
>5.76

1.89
Swartz, 1991

Swartz, 1991
Leptocheirus plumulosus
n
Amphipod,
FT,M/10
Leptoche i rus plumulosus
Dieldrin

n

n

Endrin

n

Endrin

n

Amphipod,
Hvalella azteca
Amphipod,
Hvalella azteca
Amphipod,
Hvalella azteca
Amphipod,
Hyalella azteca
Amphipod,
Hvalella. azteca
Amphipod,
Hvalella azteca
Amphipod,
Hvalella azteca
FT.M/10

FT,M/10

FT,M/10

S,M/10

S,M/10

S,M/10

S,M/10

3.66
2.97
1.7

2.9

8.7

3.0

6.1

11.2

3

678

7.3

7.3

7.3

4.2

3.8

4.3

4.1
"
3.78

5.16

5.16

5.16

4.82

4.82

4.82

4.82

11,200

1,073

1,111

3,682

147

78.7

53.6

170

4,080

1,060

1,060

1,060

277

251

284

271

2.74

1.01

1.05

3.47

0.53.

0.31

0.19

. 0.63

Swartz, 1991

Hoke and
Ankley, 1991
Hoke and
Ankley, 1991
Hoke and
Ankley, 1991
Nebeker et al.,
1989
Nebeker et al.,
1989
Nebeker et al . ,
1989
Schuytema et
al., 1989

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If
n
n
n
n
Flu<







Phei









Dranthene
n
n
n
n
M
n
H
lanthrene
H
n
*
H
Amphipod, S.M/10
Hvalella azteca
Amphipod, S.M/10
Hvalella azteca
Amphipod, S,M/10
Hvalella azteca
Amphipod, S.M/10
Hvalella azteca
Amphipod, S.M/10
Hvalella azteca
Amphipod, S.M/10
Rhepoxvnius abronius
Amphipod, S.M/10
RhepoxvniuB abronius
Amphipod, S.M/10
Rhepoxvnius abronius
Amphipod, S,M/10
RhepoxvniuB abronius
Amphipod, S.M/10
Rhepoxvniua abronius
Amphipod, S.M/10
RhepoxvniuB abronius
Amphipod, S,M/10
RhepoxvniuB abronius
Amphipod, S,M/10
Rhepoxvnius abronius
Amphipod, FT,M/10
EohauBtorius estuarius
Amphipod, FT.M/10
Eohaustorius estuarius
Amphipod, FT.M/10
Eohaustorius estuarius
Amphipod, FT,M/10
LeptocheiruB plumuloaus
Amphipod, FT,M/10
3
11
11
11
11
0
0
0
0
0
0
0
0
1
0
2
3
2
1
0
2





.18
.31
.48
.34
.34
.40
.31
.31
.02
.82
.47
.33
.97
.96
.82
.50
4.1
4.1
4.1
4.1
4.1
27.2
27.2
27.2
27.2
27.2
27.2
27.2
27.2
131
131
131
185
185
4.82
4.82
4.82
4.82
4.82
5.10
5.10
5.10
5.10
5.10
5.10
5.10
5.10
3.78
3.78
3.78
3.78
3.78
257
178
197
93.6
89.1
1,890
2,100
2,230
5,620'
4,410
3,150
3,080
2,790
4,050
3,920
3,820
8,200
6,490
271
271
271
271
271
3,420
3,420
3,420
3,420
3,420
3,420
3,420
3,420
2,550
2,550
2,550
3,610
3,610
0
0
0
0
0
0
0
0
1
1
0
0
0
1
1
1
2
1
.95
.66
.73
.35
.33
.553
.614
.652
.64
.29
.921
.900
.816
.59
.54
.50
.27
.80
Schuytema et
al., 1989
Schuytema et
al., 1989
Schuytema et
al., 1989
Schuytema et
al., 1989
Schuytema et
al., 1989
Swartz et al . ,
1990
Swartz et al . ,
1990
Swartz et al . ,
1990
DeWitt et al . ,
in press
DeWitt et al . ,
in press
DeWitt et al . ,
in press
DeWitt et al . ,
in press
DeWitt et al . ,
in press
Swartz, 1991
Swartz, 1991
Swartz, 1991
Swartz, 1991
Swartz, 1991

-------
    n           Amphipod,            FT.M/1U     .,  -      i85    3.78     u.^uo      3,610        2.27      Swartz, 1991
                Leptocheirus plumulosus         2.97

•FT =  flow-through,  M= measured concentration, s  =  static

"•Predicted LC50 /ig/Q00 =  water-only LCBO,^ X K^^oc X IKgoc/lOOOg
cPredicted Sediment  Toxic Units (PSTU) :  Measured LC50 in a sediment divided by  the predicted LC50 in sediment
                                     (water-only LC50 (fig/I*) x KOC (L/Kgoc) x 1

-------
                                                                                     12
 additional significant sediment sorption phases in addition to organic carbon or if the
 chemical has unique phases.  If the PSTU is significantly less than one, then the chemical in
 site sediments is more bioavailable than is predicted by EqP,  for example if organic carbon
 was less sorptive than indicated by KQC or if additional chemicals in the sediment are
 contributing to sediment toxicity, and the national SQC is appropriately decreased.

 Empirical Derivation Procedure

       Desciption:

       The Empirical Derivation Procedure can be used to experimentally derive a site-
 specific SQC from the results of acute and chronic toxicity tests with resident benthic species
 exposed to the chemical spiked into site sediments.



       The Empirical Derivation Procedure utilizes data from acute and chronic toxicity tests
 with resident species and spiked sediments from the site to derive a site-specific SQC.  The
 procedure assumes organic carbon nonnalization of the chemical concentration in sediments
 from the site appropriately adjusts for the bioavailability of the nonionic organic chemical. A
 sediment acceptability test, as described for the Bioavailability Procedure, is required prior to
 beginning the Empirical Derivation Procedure.  Sediments from the site are spiked with the
 chemical and a specified number of acute lethality tests with benthic species are  conducted to
 complete minimum database requirements. EPA is in the process of selecting this minimum
 database to be representative of the range of phylogeny, sensitivity, habitat/feeding type and
 community function of benthic species and meet the spirit of the minimum database
 requirements contained in WQC Guidelines (Stephan et al., 1985). This procedure can not
 be used until this database is specified.  Guidance for collection, holding, spiking, testing and
 test acceptability contained in ASTM (1992 a,b,c), Environment Canada (1993) and U.S.
 EPA (1993b), should be followed.  Valid  data from acute lethality tests that meet minimum
 database requirements will be used to calculate a Final Acute Value (FAV) using the
 procedure in the national WQC  guidelines (Stephan et al., 1985).

       Life-cycle toxicity tests with benthic species, under development by EPA and others,
 can be conducted with site sediments spiked with the chemical. Valid chronic toxicity data
 that meets minimum database requirements can be used to experimentally derive a Final
 Acute-Chronic Ratio.  Alternatively, the Acute-Chronic Ratio from the SQC document
 derived from water-only tests can be used to derive the Final Chronic Value from the
empirically derived FAV.  Future development of a suite of chronic tests with representative
benthic species may permit direct testing to derive a Final Chronic Value.

       Derivation of the Site-Specific SOCr

       The site-specific SQC is calculated by dividing the Final Acute Value (FAV) derived

-------
                                                                            13
from sediment toxicity tests by the mean Acute-Chronic Ratio (ACR) from the SQC
document or from chronic sediment tests. If the geometric mean of the Predicted Sediment
Toxic Unit (Mean PSTU) value is significantly different from that expected from the EqP
prediction, the site-specific SQC can be appropriately adjusted.

                  Site-Specific SQC = FAV/tg/goc *  ACR
                                 or
                  Site-Specific SQC = (FAV/ig/goc +  ACR) Mean PSTU

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                                                                                  14
American Society for Testing and Materials. 1992a. New Standard Guide for Collection,
       Storage, Characterization, and Manipulation of Sediments for lexicological Testing.
       ASTM Committee E-47.03.  (Draft)  52pp.

American Society for Testing and Materials. 19925. Proposed New Standard Guide for
       Conducting Solid Phase 10-Day Static Toxicity Tests with Marine and Estuarine
       Amphipods.  ASTM Committee E-47.03.  (Draft)  88pp.

American Society for Testing and Materials. 1992c. New Standard Guide for Conducting
       Solid-Phase Sediment Toxicity Tests with Freshwater Invertebrates. ASTM
       Committee B-47.03.  (Draft) 58pp.

American Society for Testing and Materials. 1989. Standard Guide for Conducting Acute
       Toxicity Tests with Fishes, Macroinvertebrates, and Amphibians.  ASTM Committee
       E-47.01, 1989 Annual Book of ASTM Standards. Volume  11.04:  336-355.

Ankley, G.T., M.K. Schubauer-Berigan, J.R. Dierkes, and M.T. Lukasewyz.  Draft:
       Sediment Toxicity Identification Evaluation: Phase I (Characterization), Phase n
       (Identification) and Phase m (Confirmation) Modifications of Effluent Procedures.

Brungs, W.A. 1991.  Synopsis of water-effect ratios for heavy metals as derived for site-
       specific water quality criteria. Final Report to Dynamac Corporation Environmental
       Services.  Response to EPA Contract 68-CO-0070, Work Assignment B-13, October,
       1991.  28pp.

Dillon, T.M., D.W. Moore and A.B. Gibson. 1993.  Development of a chronic sublethal
       bioassay for evaluating contaminated sediment with the marine polychaete worm
       Nereis (Neanthes) arenaceondentata.  Environ. Toxicol. Chem.  12(3):589-605.

Di Toro, D.M., C.S. Zarba, DJ. Hansen, WJ. Berry, R.C. Swartz, C.E. Cowan, S.P.
       Pavlou, H.E. Allen, N.A. Thomas and P.R. Paquin.  1991.  Technical basis for
       establishing sediment quality criteria for nonionic organic chemicals by using
       equilibrium partitioning.  Environ. Toxicol. Chem.  10(12): 1541-1583.

Di Toro, D.M.,  J.D. Mahony, D.J. Hansen, K.J. Scott, M.B. Hicks, S.M. Mayr and M.S.
       Redmond. 1990. Toxicity of cadmium in sediments:  The role of acid volatile sulfide.
       Environ. Toxicol. Chem.  9(12): 1487-1502.

Edmonds, W.M. and A.H. Bath. 1976.  Centrifuge extraction and chemical analysis of
       interstitial waters. Environ. Sci. Technol. 10:467-472.  Environment Canada.   1993.
       Guidelines for the collection, handling, transport, storage, and manipulation of

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                                                                                   15
       sediments for chemical characterization and toxicity tests. Conservation and
       Protection, Ottawa, Ontario, Canada.

Hoke, R. and G. Ankley. 1992. Results of re-test of Airport Pond dieldrin-spiked
       sediments. Memorandum to D. Hansen and D. Di Tore. January 27, 1992.  17p.

Hoke, R. and G. Ankley. 1991. Results of dieldrin spiking study conducted in support of
       U.S. EPA development of sediment quality criteria. Memorandum to D. Hansen and
       D. DiToro.  June 18, 1991.  9pp.

Landrum, P.P., S.R. Nihart, B.J. Eadie and W.S. Gardner. 1984.  Reverse-phase separation
       method for determining pollutant binding to Aldrich humic acid and dissolved organic
       carbon in natural waters. Environ. Sci. Technol.  18:187-192.

McGee, B.L., C.E.  Schlekat and E. Reinharz. 1993.  Assessing sublethal levels of sediment
       contamination using the estuarine amphipod Leptocheirus plumulosus. Environ.
       Toxicol. Chem.  12(3):577-587.

Pesch,  C.E., W.R. Munns, Jr., and R. Gutjahr-GobeU. 1991.  Effects of a contaminated
       sediment on life history traits and population growth rate of Neanthes arenaceodentata
       (Polychaeta: Nereidae) in the laboratory. Environ. Toxicol. Chem. 10(6):805-815.

Pesch,  C.E., R.N. Zajac, R.B. Whitlatch and M.A. Balboni.  1987.  Effect of intraspecific
       density on life history traits and population growth rate of Neanthes arenaceodentat^
       (PolychaetarNereidae) in the laboratory.  Mar. Biol. 96:545-554.

Scott, K.J. and M.S. Redmond. 1989.  The effects of a contaminated dredged material on
       laboratory populations of the tubiculous amphipod Ampelisca abdita.  Aquatic
       Toxicology and Hazard Assessment:  12th Volume. ASTM STP 1027, U.M. Cowgill
       and L.R. Williams, Eds., American Society for Testing and Materials, Philadelphia,
       PA.  pp. 289-303.

Sokal, R.R. and F.J. Rohlf. 1981. Biometry. Second Edition.  W.H. Freeman and
       Company, New York, New York. 859pp.

Stephan, C.E., D.I. Mount, D.J. Hansen, J.H. Gentile, G.A. Chapman,  and W.A. Brungs.
       1985.  Guidelines for deriving numerical national water quality criteria for the
       protection of aquatic organisms and their uses.  PB85-227049.  National Technical
       Information Service, Springfield, VA.  98pp.

Stephan, C.E., W.H. Peltier, D.J. Hansen and G.A. Chapman. In preparation. The
       determination and use of water-effect ratios of metals.

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>
f
                                                                                           16

        Swaitz, R.C., D.W. Schults, T.A. DeWitt, G.R. Ditswoith and J.O. Lamberson. 1990.
               Toxicity of fluoranthene in sediment to marine amphipods: A test of the equilibrium
               partitioning approach to sediment quality criteria.  Environ. Toxicol. Chem.
               9(8): 1071-1080.

        Swaitz, R.C. 1991.  Acenaphthene and phenanthrene files.  Memorandum to David J.
               Hansen.  June 26, 1991.  160pp.

        U.S. Environmental Protection Agency. 1983.  Guidelines for deriving site-specific water
               quality criteria for the protection of aquatic life and its uses.  Water Quality Standards
               Handbook. Office of Water Regulations and Standards.  Chapter 4,  SSpp.

        U.S. Environmental Protection Agency. 1985.  Appendix B - Responses to public comments
               on "Guidelines for deriving numerical national water quality criteria for the protection
               of aquatic organisms and their uses."  July 19, 1985.  Fed. Regist. 50:30793-30796.

        U.S. Environmental Protection Agency. 1993a.  Technical basis for establishing sediment
               quality criteria for non-ionic chemicals by using equilibrium partitioning .  (In
              preparation).

        U.S. Environmental Protection Agency. 1993b.  Guide for the use and application of
               sediment qualitv criteria for nonionic organic chemicals.  (In review).
                                                              U.S. Environmental Prcteciion Agency
                                                              Region 5, Library (P'--->j)

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