United Statas          Office of Science and Technology
Environmental Protection Agency  Health and Ecologies/ Criteria OiV.
Office of Water &        Washington, O.C. 20460
Office of Research and
Development
                                   EPA-822-R-93-013
                                   September 1993
Sediment  Quality Criteria
for the  Protection of
Benthic Organisms:
ACENAPHTHENE
                             Recycled/Recyclable
                             Printed with Soy/Canoia Ink on paper that
                             contains at least 50% recycled fiber

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                                   CONTENTS

                                                                         PAGE
Foreword	'.	ii
Acknowledgements		iv
Tables	vi
Figures	vii
Introduction	1-1
Partitioning	2-1
Toxicity of Acenaphthene: Water Exposures	'. . .  .  3-1
Toxicity of Acenaphthene (Actual and Predicted): Sediment Exposures .	4-1
Criteria Derivation for Acenaphthene	5-1
Criteria Statement	6-1
References	7-1
Appendix A:  Summary of Acute Values for Acenaphthene for	
             Freshwater and Saltwater species	A-l
Appendix B:  Summary of Data from  Sediment Spiking Experiments with
             Acenaphthene	B-l

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                                     FOREWORD
       Under the Clean Water Act (CWA) the U.S. Environmental Protection Agency (U.S.
 EPA) and the States develop programs for protecting the chemical, physical, and biological
 Integrity of the nation's waters.  Section 304(a)(l) directs the Administrator to develop and
 publish "criteria" reflecting the latest scientific knowledge on: (1) the kmd and extent of effects
 on human health and welfare, including effects on plankton, fish, shellfish, and wildlife, which
 may be expected from the presence of pollutants in any body of water, including ground water,
 (2) the concentration and dispersal of pollutants, or their byproducts, through biological, physical
 and chemical processes, and (3) the effects  of pollutants on biological community diversity,
 productivity, and stability.  Section 304(a)(2) directs the Administrator to develop and  publish
 information on, among other things, the factors necessary for the protection and propagation of
 shellfish,  fish, and wildlife for classes and categories of receiving waters.

       To meet this objective, U.S. EPA has periodically issued ambient water quality  criteria
 (WQC) guidance beginning with the publication of "Water Quality Criteria 1972" (NAS/NAE,
 1973).  All criteria  guidance through late 1986 was summarized in an U.S. EPA document
 entitled "Quality Criteria for Water, 1986" (U.S. EPA, 1987). Additional WQC documents that
 update criteria for selected chemicals and provide new criteria for other pollutants have also been
 published. In addition to the development of WQC and to continue to comply with the mandate
 of the CWA, U.S. EPA has conducted efforts to develop and publish sediment quality  criteria
 (SQC) for some of the 65 toxic pollutants or toxic pollutant categories. Section 104 of the CWA
 authorizes the administrator to conduct and promote research into the causes, effects,  extent,
 prevention, reduction and elimination of pollution, and to publish relevant information.  Section
 104(n)(l)  in particular provides for study of the effects of pollution, including sedimentation in
 estuaries,  on aquatic life, wildlife, and recreation. U.S. EPA's efforts with respect to sediment
 criteria are also authorized under CWA Section 304(a).

       Toxic contaminants in bottom sediments of the nations's lakes, rivers, wetlands, and
 coastal waters create the potential for continued environmental degradation even where water
 column contaminant levels meet established WQC. In addition, contaminated sediments can lead
 to water quality impacts, even when direct discharges to the receiving water have ceased. EPA
intends SQC be  used to assess the extent of sediment contamination, to aid in implementing
measures to limit or prevent additional contamination, and to identify and implement appropriate
remediation activities when needed.

       The criteria presented in this document are the U.S.  EPA's best recommendation of the
concentrations of a substance that may be present  in sediment while still protecting  benthic
organisms from the effects of that substance.   These criteria are applicable to a variety of
freshwater and  marine sediments  because  they are based  on the  biologically available
concentration of the  substance in sediments.  These  criteria do not protect  against additive,
synergistic or antagonistic effects of contaminants or bioaccumulative effects to aquatic life,
wildlife or human health.
                                          11

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       The criteria derivation methods outlined in this  document are proposed  to provide
protection of benthic organisms from biological impacts from chemicals present in sediments.
Guidelines and guidance are being developed by U.S. EPA to assist in the application of criteria
presented in  this document, in the development of sediment quality standards, and in other
water-related programs of this Agency.

       These criteria are being issued in support of U.S.  EPA'S regulations  and  policy
initiatives.  This document is Agency guidance only. It does not establish or affect  legal rights
or obligations. It does not establish a binding norm and is not finally determinative of the issues
addressed.  Agency decisions in  any  particular case will be made by applying the law and
regulations on the basis of the specific facts.
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                             ACKNOWLEDGEMENTS
Principal Author

    David J. Hansen

Coauthors

    Walter J. Berry
U.S. EPA, Environmental Research Laboratory,
Narragansett, RI
Science Applications International Corporation,
Narragansett, RI
    Dominic M. Di Toro  Manhattan College, Bronx, NY;
                         HydroQual, Inc., Mahwah, NJ
    Paul R. Paquin


    Laurie De Rosa
HydroQual, Inc.,
Mahwah, NJ

HydroQual, Inc.,
Mahwah, NJ
    Frank E. Stancil, Jr.   U.S. Environmental Research Laboratory, Athens, GA

    Christopher S. Zarba  U.S. EPA Headquarters, Office of Water, Washington, DC

Technical and Clerical Support

    Heinz P. Kollig       U.S. Environmental Research Laboratory, Athens, GA
    Glen B. Thursby


    Maria R. Paruta


    Dinalyn Spears

    BettyAnne Rogers
Science Applications International Corporation,
Narragansett, RI

NCSC Senior Environmental Employment Program
Narragansett, RI

Computer Science Corporation, Narragansett, RI

Science Applications International Corporation
Narragansett, RI
                                        IV

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    Persons who nave made significant contributions to the development of the approach
and supporting science used in the derivation of sediment criteria for nonionic organic
contaminants are as follows:
Herbert E. Allen

Gerald T. Anldey
                      University of Delaware, Newark, DE

                      U.S. EPA, Environmental Research Laboratory,
                     Duluth, MN
Christina E. Cowan    Battelle, Richland, WA

Dominic M. Di Toro   HydroQual, Inc., Mahwah, NJ;
                     Manhattan College, Bronx, NY
David J. Hansen


Paul R. Paquin

Spyros P. Pavlou

Richard C.  Swartz
                     U.S. EPA, Environmental Research Laboratory,
                     Narragansett, RI

                     HydroQual, Inc., Mahwah, NJ

                      Ebasco Environmental, Bellevue, WA

                     U.S. EPA, Environmental Research Laboratory,
                     Newport, OR
                      U.S. EPA, Environmental Research Laboratory,
                     Duluth, MN
Nelson A. Thomas


Christopher S. Zarba   U.S. EPA Headquarters, Office of Water, Washington, DC

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 Table 2-1.

 Table 2-2.


 Table 2-3


 Table 3-1.


 Table 3-2.



 Table 3-3.
                           TABLES
                                                              *
  Acenaphthene measured and estimated log10KoW values.

  Summary of log10KoW values for acenaphthene measured by the U.S. EPA,
  Environmental Research Laboratory, Athens, GA.
Table 4-1.

Table 4-2.


Table 5-1.

Table 5-2.


Table 5-3.

Appendix A.

Appendix B.
 Summary of K^. values for acenapthene derived from literature sorption isotherm
 data.

 Chronic sensitivity of freshwater and saltwater organisms to acenaphthene. Test
 specific data.

 Summary of Freshwater and Saltwater acute and chronic values, acute-chronic
 ratios, and derivation of final acute values, final acute-chronic ratios, and final
 chronic values for acenaphthene.

 Results of approximate randomization test for the equality of freshwater and
 saltwater FAV distributions for acenaphthene and approximate randomization test
 for the equality of benthic and combined benthic and water column (WQC) FAV
 distributions.

 Summary of tests with acenaphthene-spiked sediment.

 Water-only and sediment LCSOs used to test the applicability of the equilibrium
 partitioning theory for acenaphthene.

 Sediment quality criteria for acenaphthene.

 Analysis of variance for derivation of sediment quality criteria confidence limits
 for acenaphthene.

 Sediment quality criteria confidence limits for acenaphthene.

- Summary of acute values for acenaphthene for freshwater and saltwater species.

- Summary of data from sediment spiking experiments with acenaphthene. Data
 from these experiments were used to calculate KQC values (Figure 2-1) and to
 compare mortalities of amphipods with pore water toxic units (Figure 4-1) and
 predicted sediment toxic units (Figure 4-2).
                                          VI

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                                       FIGURES
Figure 1-1.    Chemical structure and physical-chemical properties of acenaphthene.       v

Figure 2-1.    Organic carbon-normalized  sorption  isotherm  for  acenaphthene  (top)  and
              probability plot of Koc (bottom) from sediment toxicity tests conducted by Swartz
              (1991). The line in the top panel represents the relationship predicted with a log
                 of 3.76, that is Cij08=KOB • Cd.
Figure 3-1.   Genus mean acute values from water only acute toxicity tests using freshwater
             species vs. percentage rank of their sensitivity. Symbols representing benthic
             species are solid, those  representing water column species are open.  Asterisks
             indicate greater than values. A = adult, J  =  juvenile,  N  =  nymph, X =
             unspecified life stage.

Figure 3-2.   Genus mean acute values from water only acute toxicity tests using saltwater
             species vs. percentage rank of their sensitivity. Symbols representing benthic
             species are solid, those representing water column species are open.  Asterisks
             indicate greater than values. E = embryo, J  = juvenile.

Figure 3-3.   Probability distribution of FAV difference statistics to compare water-only data
             from freshwater vs. saltwater (upper panel) and benthic vs. WQC (lower panel)
             data.

Figure 4-1.   Percent  mortality of amphipods in sediments  spiked  with acenaphthene or
             phenanthrene (Swartz, 1991), endrin (Nebeker et.al., 1989; Schuytema et al.,
             1989), or fluoranthene (Swartz et al., 1990), and midge in sediments spiked with
             dieldrin (Hoke, 1992) or kepone (Adams et al. , 1985) relative to pore water toxic
             units.  Pore water toxic units are ratios of concentrations of chemicals measured
             in individual treatments divided by the water-only LC50 value from water-only
             tests. (See Appendix B hi this SQC document, Appendix B hi the endrin, dieldrin
             fluoranthene and phenanthrene SQC documents, and original references for raw
             data.)

Figure 4-2.   Percent  mortality of amphipods hi sediments  spiked  with acenaphthene or
             phenanthrene (Swartz, 1991), dieldrin (Hoke and Ankley, 1991), endrin (Nebeker
             et al.,  1989; Schuytema  et al.,  1989) or  fluoranthene (Swartz et al., 1990; De
             Witt et al., 1992) and midge in dieldrin spiked sediments (Hoke, 1992) relative
             to "predicted sediment toxic units. "  Predicted sediment toxic units are the ratios
             of measured treatment concentrations for each chemical hi sediments 0*g/goc)
             divided by the predicted  LC50 Otg/g0c) to sediments (KoC x Water-only LC50,
             /Kg/L).   (See Appendix  B hi this document  and Appendix B hi the  dieldrin,
             endrin, fluoranthene, and phenanthrene SQC documents for raw data).
                                          Vll

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Figure 5-1.   Comparison between SQC concentrations and 95% confidence intervals, effect
             concentrations from benthic organisms exposed to acenaphthene-spiked sediments
             and sediment concentrations predicted to be chronically safe  in fresh water
             sediments.  Concentrations predicted to be chronically safe (Predicted Genus
             Mean Chronic Values, PGMCV) are derived from the Genus Mean Acute Values
             (GMAV) from water-only 96-hour lethality tests, Acute Chronic Ratios (ACR)
             and KQC values. PGMCV  = (GMAV -s- ACR)Koc. Symbols for PGMCVs are A
             for arthropods, O for fishes and D for other invertebrates.  Solid symbols are
             benthic genera; open symbols water column genera. Arrows indicate greater than
             values.   Error bars around sediment LC50 values indicate observed range of
             LCSOs.

Figure 5-2.   Comparison between SQC concentrations and 95% confidence intervals, effect
             concentrations from benthic organisms exposed to acenaphthene-spiked sediments
             and sediment concentrations predicted to be  chronically safe in  salt water
             sediments.  Concentrations predicted to be chronically safe (Predicted Genus
             Mean Chronic Values, PGMCV) are derived from the Genus Mean Acute Values
             (GMAV) from water-only 96-hour lethality tests, Acute Chronic Ratios (ACR)
             and KQC values. PGMCV  = (GMAV * ACR)KoC. Symbols for PGMCVs are
             A for arthropods, O for fishes and D for other invertebrates. Solid symbols are
             benthic genera; open symbols water-column genera. Arrows indicate greater than
             values.   Error bars around sediment LC50 values indicate observed range of
             LCSOs.

Figure 5-3.   Probability distribution of concentrations of acenaphthene in  sediments from
             streams, lakes and estuaries in the United States from 1986 to  1990  from the
             STORET (U.S. EPA, 1989b) database, compared to the acenaphthene SQC values
             of 13 pg/g in freshwater sediments having TOC = 10% and 1.3  pg/g in
             freshwater sediments having TOC =  1% and compared to SQC values for
             saltwater sediments of 23 pg/g when TOC =10% and 2.3 pg/g when TOC=1 %.
             The upper dashed line on each figure represents the SQC value when  TOC =
             10%, the lower dashed line represents the SQC when TOC = 1 %.

Figure 5-4.   Probability distribution of concentrations of acenaphthene in  sediments from
             coastal and estuarine sites  from 1984 to 1989 as measured by the National Status
             and Trends Program (NOAA, 1991).  The horizontal line is the saltwater SQC
             value of 230
                                       vui

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                                  DISCLAIMER
      This report has been reviewed by the Health and Ecological Criteria Division, Office of
Science and Technology, U.S. Environmental Protection Agency, and approved for publication.
Mention  of trade  names or  commercial products  does not constitute  endorsement  or
recommendation for use.
                             AVATT.ABTTJrTY
      This document is available to the public through the National Technical Information
Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161.  NITS Accession Number
xxxx-xxxxxx.
                                        IX

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                                      SECTION 1








                                   INTRODUCTION




1.1  GENERAL INFORMATION



       Under the Clean Water Act (CWA) the U.S. Environmental Protection Agency (U.S.




EPA) is responsible for protecting the chemical, physical and biological integrity of the nation's




waters. In keeping with this responsibility, U.S. EPA published ambient water quality criteria




(WQC) in 1980 for 64 of the 65 toxic pollutants or pollutant categories designated as toxic in



the CWA.  Additional water quality documents that update criteria for selected consent decree




chemicals and  new criteria have been  published since 1980.  These WQC are numerical




concentration limits that are the U.S. EPA's best estimate of concentrations protective of human



health and the presence and uses of aquatic life.  While these WQC play an important role in



assuring a healthy aquatic environment, they alone are not sufficient to ensure the protection of



environmental or human health.




       Toxic pollutants in bottom sediments of the nation's lakes, rivers, wetlands, estuaries and




marine coastal waters create the potential for continued  environmental degradation even where



water-column concentrations comply with established WQC.    In  addition, contaminated



sediments can be a significant pollutant source that may cause water quality degradation to



persist, even when other pollutant sources  are stopped. The absence of defensible  sediment




quality criteria (SQC) makes it difficult to accurately assess the extent of the ecological risks of
                                          1-1

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 contaminated sediments and to identify, prioritize and implement appropriate clean up activities



 and source controls.  As a result of the need for a procedure to  assist regulatory agencies in



 making decisions concerning contaminated sediment problems, a  U.S. EPA Office of Science



 and Technology, Health  and Ecological Criteria Division  (OST/HEC)  research team  was



 established to review alternative approaches  (Chapman, 1987). All of the approaches reviewed



 had both strengths and weaknesses and no single approach was found to be applicable for SQC



 derivation in all situations (U.S. EPA, 1989a). The equilibrium partitioning (EqP) approach was



 selected for nonionic organic chemicals because it presented the greatest promise for generating



 defensible national numerical chemical-specific SQC applicable across a broad range of sediment



 types.  The three principal observations that underlie the EqP method of establishing SQC are:



       1.     The concentrations of nonionic organic chemicals in sediments,  expressed on an



             organic carbon basis, and in pore waters correlate to observed biological effects



             on sediment dwelling organisms across a range of sediments.



       2.     Partitioning models can relate sediment concentrations  for nonionic organic



             chemicals on an organic carbon basis to freely dissolved  concentration in pore



             water.



       3.     The distribution of sensitivities of benthic and water column organisms to



             chemicals are similar; thus, the currently established WQC final chronic value



             (FCV) can be used to define  the acceptable effects concentration of a chemical



             freely dissolved in pore water.



       The EqP approach, therefore, assumes that: (1) the partitioning of the chemical between



sediment organic carbon and interstitial water is stable at equilibrium; (2) the  concentration in
                                          1-2

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 either phase  can be  predicted  using appropriate  partition coefficients  and the  measured




 concentration in the other phase; (3) organisms receive equivalent exposure from water-only



 exposures  or from any equilibrated phase: either from pore water via respiration, sediment




 integument exchange,  sediment via ingestion or from  a mixture of exposure routes; (4) for




 nonionic chemicals, effect concentrations in sediments on  an organic carbon basis can be




 predicted using the organic carbon partition coefficient (Koc) and effects concentrations in water;




 and (5) the FCV concentration  is an appropriate effects concentration for  freely-dissolved




 chemical in interstitial water; and (6) the SQC (/tg/goc) derived as the product of the K^ and




 FCV is protective of benthic organisms.  SQC concentrations presented in this document are




 expressed  as  jtg chemical/g sediment organic carbon  and not on an interstitial  water  basis



 because: (a) pore water is difficult to adequately sample;  and (b) significant amounts of the




 dissolved chemical may be associated with dissolved organic carbon; thus,  total chemical



 concentrations in interstitial water may overestimate exposure.




        The  data that support the EqP approach  for deriving SQC for nonionic organic



 chemicals are reviewed by Di Toro et al (1991) and U.S.EPA, (1993a). Data supporting  these



observations for acenaphthene are presented in this document.




       SQC generated using the EqP method are suitable for use in providing guidance to



regulatory  agencies because they  are:



       1.   numerical values;



       2.   chemical specific;




       3.   applicable to most sediments;




       4.   predictive of biological effects; and
                                           1-3

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       5. protective of benthic organisms.




As is the case with WQC, the SQC reflect the use of available scientific data to:  1) assess the



likelihood of significant environmental effects to benthic organisms from chemicals in sediments;




and 2) to derive regulatory requirements which will protect against these effects.




       It should be emphasized that these criteria are intended to protect benthic organisms from



the effects of chemicals associated with sediments.   SQC are intended  to apply to sediments



permanently inundated with water, intertidal sediment and to sediments inundated periodically




for durations sufficient to permit development of benthic assemblages.  They do not apply to




occasionally inundated soils containing terrestrial organisms. These criteria do not address the



question of possible contamination of upper trophic level organisms or the synergistic, additive



or antagonistic effects of multiple chemicals. SQC addressing these issues may result in values




lower or higher than those presented in this document.  The SQC presented in this document



represent the U.S. EPA's best recommendation at this time of the concentration of a chemical




in sediment that will not adversely affect most benthic organisms.  SQC values may be adjusted



to account for future data or site specific considerations.



       SQC values may also need to be adjusted because of site specific considerations.  In spill



situations, where chemical equilibrium between water and sediments has not yet been reached,



a sediment chemical concentration less than the SQC may pose risks to benthic organisms. This



is because for spills, disequilibrium concentrations in interstitial and overlying water may be




proportionally higher relative to sediment concentrations. Research has  shown that the source




or "quality" of total organic carbon (TOC) in the sediment does not greatly affect chemical




binding (DeWitt et al., 1992). However, the physical form of the chemical in the sediment may
                                         1-4

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 have an effect. At some sites concentrations in excess of the SQC may not pose risks to benthic




 organisms, because the compound may be a component of a particulate, such as coal or soot,



 exceed solubility such as undissolved oil. In these situations, the national SQC would be overly




 protective of benthic organisms and should  not be used unless modified using the procedures




 outlined in the "Guidelines for the Derivation of Site-Specific Sediment Quality Criteria" (U.S.




 EPA, 1993b).  The SQC may be underprotective where the toxicity of other chemicals are



 additive with the SQC chemical or species of unusual sensitivity occur at the site.




      This  document presents the  theoretical  basis and the  supporting data relevant to the




 derivation of the SQC for acenaphthene. An understanding of the "Guidelines for Deriving




 Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their



 Uses" (Stephan et al., 1985), response to public comment (U.S. EPA, 1985) and "Technical




 Basis for Deriving Sediment Quality Criteria for Nonionic Organic Contaminants By Using



 Equilibrium  Partitioning for the  Protection of Benthic Organisms"  (U.S.  EPA,  1993a)  is




 necessary in order to understand the following text, tables and calculations.  Guidance for the



 acceptable use of SQC values is contained in " Guide for the Use and Application of Sediment



 Quality Criteria for Nonionic Organic Chemicals" (U.S. EPA, 1993c).








 1.2 GENERAL INFORMATION: ACENAPHTHENE:




      Acenaphthene is a member of the polycyclic aromatic hydrocarbon  (PAH) group of



 organic compounds.  It occurs both naturally in coal tar, and as a by product of manufacturing



processes such as petroleum refining, shale oil processing and  coal tar distilling (Verschueren,




 1983). Other man made sources of acenaphthene  include its generation as a by product of the
                                        1-5

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combustion of tobacco, and its presence in asphalt and in soots generated by the combustion of



aromatic  fuels amt;ii=d  with pyridine (Verschueren,  1983).   Acenaphthene is used  in



manufacturing processes to produce dyes, plastics, insecticides and fungicides (Windholtz et al.,



1983).  Some PAHs are of environmental concern because they are known to be carcinogens



and/or mutagens (Brookes, 1977). With an increase in fossil fuel consumption in the United



States an  increase in emissions of PAHS to the environment can be expected over the next



several decades (Eadie et al., 1982).



       Acenaphthene has a two ring bridged structure (Figure 1-1).  It has a solubility in water



at 25°C of 3.94 mg/1 (Miller et al., 1985), and is a solid at room temperature  (melting point of



116°C).  Two significant processes which can influence the fate of acenaphthene in  sediment



are sorption and biodegradation (U.S. EPA, 1980).  Sorption of acenaphthene onto solids in the



water column and subsequent settling, as well as partitioning onto organics in the sediment, can



significantly affect acenaphthene transport.  Bioaccumulation is a short-term process in which



PAHs with 4 rings or less are metabolized and long-term partitioning into biota is not considered



a significant fate process (U.S. EPA, 1980).  Other processes found to have little or no effect



on the fate of acenaphthene in the sediment are oxidation, hydrolysis and volatilization (U.S.



EPA, 1980).



       The acute toxicity of acenaphthene from individual toxicity tests ranges from 120.0 to



2,045 /tg/L for freshwater and  160 to 16,440 jcg/L for saltwater organisms (Appendix A).



Differences between concentrations of acenaphthene causing acute lethality and chronic toxicity



are small; acute-chronic ratios range from 1.5 to 6.7 (Table 3-3).  Although acenaphthene



bioaccumulates in aquatic biota, the associated health or ecological risks are unknown.
                                          1-6

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            MOLECULAR FORMULA
            MOLECULAR WEIGHT
            DENSITY
            MELTING POINT

            PHYSICAL FORM

            VAPOR PRESSURE
154.21
1.069 g/cc @ 20°C
90-95°C

Orthorhpmbic
bipyramidal needles
0.0026 mPa (25°C)
            CAS NUMBER:
            CHEMICAL NAME:
83-32-9
1,2-Dihydroacenaphthylene;
periethylenenaphthalene;
1,8-ethylenenaphthalene
Figure 1-1.  Chemical structure and physical-chemical properties of acenaphthene.
                                    1-7

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 1.3  OVERVIEW OF DOCUMENT:




       Section 1 provides a brief review of EqP methodology, and a summary of the physical-



 chemical properties and aquatic toxicity of acenaphthene. Section 2 reviews a variety of methods



 and  data useful in deriving partition coefficients for acenaphthene and includes the  KQC



 recommended for use in the derivation of the acenaphthene SQC.   Section 3 reviews aquatic



 toxicity data contained in the acenaphthene WQC document (U.S. EPA, 1980) and new data that



 were used to derive the Final Chronic Value (FCV) used in this document to derive the SQC




 concentration.  In addition, the comparative sensitivity of benthic and water column species is



 examined as the justification for the use of the FCV for acenaphthene in the derivation of the




 SQC. Section 4 reviews data on the toxicity of acenaphthene in sediments, the need for organic



 carbon normalization of acenaphthene sediment concentrations and the  accuracy of the EqP



prediction of sediment toxicity using KQC and an effect concentration in water. Data from



Sections 2, 3 and 4 are used in Section 5  as the basis for the  derivation of the SQC for




acenaphthene and its uncertainty.  The SQC for acenaphthene  is then compared to  STORET



(U.S. EPA, 1989b) and National Status and Trends  (NOAA,  1991) data on acenaphthene's



environmental occurrence in sediments.  Section 6 concludes with the  criteria  statement for



acenaphthene.  The references used in this document are listed in Section 7.
                                        1-8

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                                     SECTION 2.




                                   PARTITIONING








 2.1  DESCRIPTION OF THE EQUILIBRIUM PARTITIONING METHODOLOGY:




       Sediment quality criteria (SQC) are the numerical concentrations of individual chemicals



 which are intended to be predictive of biological effects, protective of the presence of benthic




 organisms and applicable to the range of natural sediments from lakes, streams, estuaries and




 near coastal marine waters. As a consequence, they can be used in much the same way as water




 quality criteria (WQC); ie., the concentration of a chemical which is protective of the intended




 use such as aquatic life protection. For non-ionic organic chemicals, SQC are expressed as




 Hg chemical/g organic carbon and apply to sediments having  ^ 0.2% organic carbon by dry




 weight.  A brief overview follows of the concepts which underlie the equilibrium partitioning



 methodology for deriving SQC.  The methodology is discussed in detail in the "Technical Basis



 for Deriving Numerical National Sediment Quality Criteria for Nonionic Organic Contaminants




 by Using Equilibrium Partitioning for the Protection of Benthic  Organisms" (U.S. EPA, 1993a),



hereafter referred to as the SQC Technical Basis Document.




      Bioavailability of a chemical at a particular sediment concentration often differs from one



 sediment type to another. Therefore, a method is  necessary for  determining a SQC based on the




bioavailable chemical fraction  in a  sediment.    For  nonionic organic  chemicals, the



concentration-response relationship for the biological  effect  of concern can most often be




correlated  with the interstitial water (i.e., pore  water) concentration  0*g chemical/liter pore
                                        2-1

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water) and not to the sediment chemical concentration (jj.g chemical/g sediment) (Di Toro et al.,



1991).  From a purely practical point of view, this correlation suggests that if it were possible



to measure  the pore water chemical concentration, or predict it from the total sediment




concentration and the relevant sediment properties, then that concentration could be used to



quantify the exposure concentration for an organism.  Thus, knowledge of the partitioning of



chemicals between the solid and liquid phases in a sediment is a necessary component for



establishing  SQC.  It is for this reason that the methodology described below is called the



equilibrium partitioning (EqP) method.




       It is shown in the SQC Technical Basis Document (U.S. EPA, 1993a) that the final acute




values (FAVs) in the WQC documents are appropriate for benthic species for a wide range of



chemicals. (The data showing this for acenaphthene are presented in Section 3). Thus, a SQC




can be  established using  the final  chronic value (FCV) derived using the  WQC Guidelines



(Stephan et al.,  1985) as the acceptable effect concentration in pore or overlying water (see




Section 5), and the partition coefficient can be used to relate the pore water concentration to the



sediment concentration via the partitioning equation.  This acceptable concentration in sediment



is the SQC.




       The calculation is as follows: Let FCV (fig/L) be the acceptable concentration in water




for the chemical of interest; then compute the SQC  using the partition coefficient, (Kp,




L/Kg»cdiment)>   between sediment and water:



                                 SQC = KpFCV                               (2-1)



This is the fundamental equation used to generate the SQC.  Its utility  depends  upon the



existence of a methodology for quantifying the partition coefficient, Kp.
                                         2-2

-------
       Organic carbon appears to be the dominant sorption phase for nonionic organic chemicals




in naturally occurring sediments and thus controls the bioavailability of these compounds in



sediments.  Evidence for this can be found in numerous toxicity tests, bioaccumulation studies




and chemical analyses of pore water and sediments (Di Toro et al., 1991).  The evidence for



acenaphthene is discussed  in this section and section 4.   The organic carbon binding of a




chemical in sediment is a function of that chemical's organic carbon partition coefficient and the




weight fraction of organic carbon in the sediment (foe)-  The relationship is as follows:
                                                                              (2-2)




      It follows that:




                          SQCoc = KocFCV                                   (2-3)








where SQCOC is the sediment quality criterion on a sediment organic carbon basis.



      KQC is  not  usually measured directly (although it can be done,  see  section 2.3).



Fortunately, KQC is  closely related to the octanol-water partition coefficient (Kow) (equation 2-5)




which has been measured for many compounds, and can be measured very accurately: The next



section reviews the available information on the KQW for acenaphthene.








2.2 DETERMINATION OF KQW FOR ACENAPHTHENE:




      Several approaches have been used to determine KQW for derivation of  SQC, as discussed



in the SQC Technical Basis Document.  At the U.S. EPA, Environmental Research Laboratory



at Athens, GA (ERL,A), three methods were selected for measurement and two for estimation
                                         2-3

-------
of KOW'S. The measurement methods were shake-centrifugation (SC) and generator column

(GCol), and slow stir-flask (SSF) and the estimation methods were SPARC (SPARC Performs

Automated Reasoning in Chemistry; Karickhoff et al., 1989) and CLOGP (Chou and Jurs,

1979). Data were also extracted from the literature. The SC method is a standard procedure

in the Organization for Economic Cooperation and Development (OECD) guidelines for testing

chemicals, therefore, it has regulatory precedence.


TABLE 2-1. ACENAPHTHENE MEASURED AND ESTIMATED LOGioKoW VALUES
METHOD
Measured
Estimated
Estimated
Estimated
Estimated
Estimated
Estimated
Estimated
Estimated
Estimated
Estimated
LOG10KoW
3.92
3.70
3.88
3.92
3.98
4.03
4.07
4.15
4.22
4.33
4.43
REFERENCE
Banerjee etal., 1980
Yalkowsky etal., 1983
SPARC4
Miller etal., 1985
Mabey etal., 1982
Yalkowsky et al., 1979
CLOGP"
Mackay etal., 1980
Kamletetal., 1988
Callahan et al., 1979
Arbuckle 1983
      •SPARC is from SPARC Performs Automated Reasoning in Chemistry, (Karickhoff et
      al., 1989).
      bCLOGP is an algorithm that is included in the database QSAR located at the U.S. EPA,
      Environmental Research Lab., Duluth, MN (Chou and Jurs, 1979).
      In an examination of the literature data for acenaphthene, only one primary reference was

found, with a measured log10KoW value of 3.92 (Banerjee et al., 1980) (Table 2-1).  Several

primary references were found for estimated log10KoW values in the literature ranging from 3.70

to 4.43 (Table 2-1). Although the range of reported values for acenaphthene is significantly
                                       2-4

-------
lower than the range of values for some other compounds, it is relatively large, and we were not
                                               *   '                      *•
able to determine from studying the primary articles that any value was more likely to be

accurate than any other.

       KQW values for SPARC and CLOGP are also included in Table 2-1.   SPARC is a

computer expert system under development at ERL,A, and the University of Georgia, at Athens.

The CLOGP algorithm is included in the database QSAR located at EPA's Environmental

Research Laboratory (ERL,D) at Duluth, Minnesota.  For more information on SPARC and

CLOGP see  U.S.  EPA (1993a).  The SPARC estimated log10KoW value for acenaphthene is

3.88.  The CLOGP program estimate of the logioKoW value for acenaphthene using structure

activity relationships is 4.07.

       We had littie confidence in the available measured or estimated values for KQW, therefore

the SC, GCol, SSF methods were used to provide additional data from which to define KQW

acenaphthene (Table 2-2).  The SC method yielded a log10KoW = 3.84 (n=4), the GCol method

yielded a log10KoW =  4.17  (n=4), and the SSF method yielded a log10KoW =  3.83 (n=3).

Comparison of the results from the SC, GCol, SSF and SPARC KQW determination methods for

the five chemicals for which SQC are currently being developed (acenaphthene, dieldrin, endrin,

fluoranthene and phenanthrene) indicate that the SSF method provides the best estimate of KQW

(U.S. EPA, 1993a).  The SSF method had less variability, less experimental bias (Bias is defined

as the  mean difference between the best-fit estimate of KQW using all four methods and the

estimates from each method.) and was generally in the range  of the SC, GCol, and SPARC

methods (U.S. EPA, 1993a).   Therefore, the SSF value of 3.83  is the value  for log10KoW

recommended for SQC derivation. This value agrees with the SPARC estimated value and the
                                        2-5

-------
average of the values measured by the three methods under carefully controlled conditions at
                                                                   *

ERL, A. This KQW is the logarithm of the mean of three KQW measurements made by SSF.  The


logs of the KQW values measured by SSF range from 3.81 to 3.84.
TABLE 2-2.  SUMMARY OF  LOG10KoW VALUES FOR ACENAPHTHENE MEASURED
      BY THE U.S. EPA, ENVIRONMENTAL RESEARCH LABORATORY,
      ATHENS , GA.
SHAKE-
CENTRIFUGATION
3.82
3.84
3.88
3.84
3.84
GENERATOR
COLUMN
4.18
4.17
4.16
4.17
4.17
SLOW STIR
FLASK
3.81
3.84
3.84
3.83
      •Logic of mean measured values.




2.3 DERIVATION OF KOC FROM ADSORPTION STUDIES:

      Two types of experimental measurements of the KOC are available.  The first type

involves experiments which  were designed to measure the partition coefficient in particle

suspensions.  The second type of measurement is from  sediment toxicity tests in which

measurements of sediment acenaphthene, sediment organic carbon (OC) and non-dissolved

organic carbon (DOC) associated acenaphthene in pore water were used to compute KOC.
 2.3.1 KOC FROM PARTICLE SUSPENSION STUDIES:

      Laboratory studies to characterize adsorption are generally conducted using particle



                                     2-6

-------
suspensions.  The high concentrations of solids and turbulent conditions necessary to keep the
                                                                          •*
mixture in suspension make data interpretation difficult as a result of a particle interaction effect.

This effect suppresses the partition coefficient relative to that observed for undisturbed sediments

(Di Toro, 1985; Mackay and Powers, 1987).

       Based on analysis  of an extensive body of experimental data for a wide range  of

compound types and experimental conditions, the particle interaction model (Di Toro, 1985)

yields the following relationship for estimating KP:
               oe
                                                                           (2-4)
           1 + mf
                  oc
where m is the particle concentration in the suspension (kg/L), and % =  1.4, an empirical
constant.
In this expression the KQC is given by:

             log10Koc = 0.00028 + 0.983 log10KoW                        (2-5)


       A sorption isotherm experiment that demonstrates the effect of particle suspensions was

found in a comprehensive literature search for partitioning information for acenaphthene (Table

2-2) (Mihelcic and Luthy, 1988).  The experiment with four different concentrations of particles

in suspension showed an observed Kp of 52 L/kg for an acenaphthene solution and soil (2.9 +.

0.28% organic carbon).  Calculated Kp using KQC (Equation 2-5) and foc is 175 L/kg.  The

difference between the observed and calculated Kp can be explained by particle interaction

effects.  Particle interaction results  in a  lower observed partition coefficient.  The particle

interaction model (Equation 2-4) predicts Kp of 36.8 L/kg to 6.7 L/kg for respective solids

                                         2-7

-------
 concentrations of 0.03 kg/L to 0.20 kg/L which is in order with the observed Kp.  Log10KoC

 computed from observed Kp and f^ is 3.25. This value is lower than K<,c from laboratory

 measurements as a result of particle effects.  This data is presented as an example of particle

 effects only, as 100 percent reversibility is assumed in the absence of a desorption study and an

 actual KQC can not be computed.
       TABLE 2-3. SUMMARY OF KQC VALUES FOR ACENAPHTHENE DERIVED
                   FROM LITERATURE SORPTION ISOTHERM DATA.
       Observed                 Solids
       LogjoKoc           n     (kg/L)              Reference


        3.25        1      0.03-0.20                 Milhelcic and
                                                         Luthy, 1988
       In the absence of particle effects, KOC is related to KQW via Equation 2-5, shown above.

For log10Kow = 3.83 (ERL,A mean measured value), this expression results hi an estimate of

log10Koc = 3.76
2.3.2 KQC FROM SEDIMENT TOXKTTY TESTS:

      Measurements of KQC are available from sediment toxicity tests using acenaphthene

(Swartz, 1991). These tests are from three marine saltwater sediments having a range of organic

carbon contents of 1.02 to 4.37 percent (Table 4-1; Appendix B).  Acenaphthene concentrations

were measured in the sediments and pore waters providing the data necessary to calculate the

partition coefficient for an undisturbed bedded sediment. The pore water measurements did not

                                        2-8

-------
 increase at values greater than 1,000 /ttg/L suggesting that the limit of aqueous solubility was




 being approached.  These tests were run at 15°C, but a literature search for acenaphthene



 revealed no solubility data at this temperature. Solubility for acenaphthene is reported as 3.94




 mg/L at 25°C  (Miller et al., 1985), supporting the idea of saturation limitation.  As a result,



 computations  for the partition coefficient did not  include treatments where pore  water




 concentrations were greater than 1,000/tg/L.




       The upper panel of Figure 2-1  is a plot of the organic carbon-normalized sorption




 isotherm for acenaphthene where the sediment acenaphthene concentration Og/goc) is plotted




 versus pore water concentration 0*g/L).  The data used  to  make this  plot are included  in




 Appendix B. Data from treatments where pore water concentrations were greater than 1,000



 Atg/L were not included on the plot.  The line of unity slope corresponding to the log10KoC  =




 3.76 is compared to the data.  A probability plot of the observed experimental log10KoC values




 is shown in lower panel of Figure 2-1.   The logi^oc values are approximately normally



 distributed with a mean of log10KoC = 3.58 and a standard error of the mean of 0.012. This



 value is  statistically indistinguishable from logxoKoc = 3.76, which was computed from the



 experimentally determined acenaphthene log10KoW of 3.83 Equation 2-5.








2.4 SUMMARY OF DERIVATION OF KQC FOR ACENAPHTHENE:




       The Koc selected to calculate the sediment quality criteria for acenaphthene is based on



the regression of log10KoC from log10KoW (Equation 2-5), using the  acenaphthene log10ECoW of



3.83 recently measured by ERL,A.  This approach rather than the use  of the KQC from the




toxicity test was adopted because the regression equation is based on the most robust data set
                                          2-9

-------
                               ACENAPHTHENE
     100000
      10000
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        100
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              PORE  WATER CONCENTRATION (ug/L)
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                                                 Illl 1 1 1 1 1 •  IIIIIII 1
                                                 Illl 1 1 1 1 1   IIIIIII 1 1
          0.1
        10  20     60     80  80
                              PROBABILITY
 Figure 2-1.   Organic carbon-normalkdd sorption isotherm for  acenaphthene  (top)  and
             probability plot of Koc (bottom) from sediment toxicity tests conducted by Swartz
             (1991). The line in the top panel represents the relationship predicted with a log
                of 3.76, that is C^-Ko. • Cd.
                                     2-10

-------
available that spans a broad range of chemicals and particle types, thus encompassing a wide




range of KQW and f^. The regression equation yields a log10KoC = 3.76. This value is in very



good agreement with the log10Koc of 3.58 measured in the sediment toxicity tests.
                                        2-11

-------

-------
                                   SECTION 3


              TOXICITY OF ACENAPHTHENE: WATER EXPOSURES


3.1 TOXICITY OF ACENAPHTHENE IN WATER: DERIVATION OF ACENAPHTHENE
   WATER QUALITY CRITERIA:

    The equilibrium partitioning (EqP) method for derivation of sediment quality criteria (SQC)

uses the acenaphthene water quality criteria (WQC) final Chronic Value (FCV) and partition

coefficients (KoC) to estimate the maximum concentrations of nonionic organic chemicals in

sediments, expressed on an organic carbon basis, that will not cause adverse effects to benthic

organisms. For this document, life stages of species classed as benthic are either species that

live in the sediment (infauna) or on the sediment surface (epibenthic) and obtain their food from

either the sediment or water column (U.S.EPA, 1989c). In this section (1) the FCV from the

acenaphthene WQC document (U.S. EPA, 1980) is revised using new aquatic toxicity test data,

and (2) the use of this FCV is justified as the effects concentration for SQC derivation.

3.2 ACUTE TOXICITY-WATER EXPOSURES:

    Twenty standard  acute toxicity tests with acenaphthene have been conducted  on 10

freshwater species from 10 genera (Appendix A).  Overall genus mean acute values (GMAVs)

range from 120 to 2,045 jtg/L.  Three invertebrates and two fishes were among the most

sensitive  species; overall GMAVs for these taxa range from 120 to 670 /*g/L.  Tests on the

benthic life-stages  of  5 species  from  5 genera are contained in this database  (Figure 3-1;

Appendix A).  Benthic organisms were among both the most sensitive, and most resistant,

freshwater genera to acenaphthene; GMAVs range from 240 and  > 2,040 jtg/L.  Three

                                       3-1

-------
   10000 r
                 A Arthropods
                 D Other Invertebrates
                 O Fishes
                                                     Lepomis (J)
                                                       Bluegill
                                                                          Snail

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                                                                  Ictalurus (J)       Mid9e
                                                                    Catfish
    1000
                                                         Pimephales (A,J)
                                                            Minnow
                             Oncorhynchus (J)
                                  Trout
                                   Gammarus (X)
                                     Amphipod
                            Pettopeita (X)
                              Stonefly
      100
                  JL
                     Daphnia (X)
                     Cladoceran
                       —I	
                                        _L
J.
_L
                         20             40            60            80

                       PERCENTAGE RANK OF FRESHWATER GENERA
                                                                                  100
 Figure 3-1.   Genus mean acute values from water only acute toxicity tests using freshwater
              species vs.  percentage  rank of their sensitivity. Symbols representing  benthic
              species are  solid, those representing water column species are open.  Asterisks
              indicate greater than values. A  =  adult, J = juvenile, N  = nymph, X =
              unspecified life stage.
                                           3-2

-------
epibenthic species, stoneflies, a snail and channel catfish, were tested.  Two infaunal species




were tested, including the amphipod, Gammarus minus (LC50 = 460 pg/lL), and the midge,



Paratanvtarsus sp. (LC50 = 2,045 /tg/L).  The FCV derived from the overall GMAVs (Stephan



et al., 1985) for freshwater organisms is 80.01 (Table 3-2).




    Twenty-one acute toxicity tests have been conducted on 10 saltwater species from 10 genera




(Appendix A).   Overall GMAVs  range from 245.0 to 8,163 jtg/L., similar to the range for




freshwater genera.  Crustaceans were most sensitive; GMAVs range from 245.0 to 1,125 /tg/L.




Benthic life-stages from 6 species from 6 genera have been tested (Figure 3-2; Appendix A).




They are among both the most sensitive, and most resistant,  saltwater genera to acenaphthene.



The most  sensitive benthic species is the sand shrimp, Crangon septemspinosus. with a 96-hour




LC50 of 245.0 jig/L based on unmeasured concentrations.  The mysid, Mysidopsis bahia. has




a similar  sensitivity  with an  average, flow-through 96-hour LC50 of 317.7 jig/L based on




measured  concentrations.  Other benthic species for which there are data appear less sensitive;




GMAVs range from 589.4 to 7,693 /*g/L.  The FAV derived from the overall GMAVs (Stephan



et al.,  1985) for saltwater organisms is 140.8 jtg/L (Table 3-2).








3.3 CHRONIC TOXICITY - WATER EXPOSURES:




   Chronic  life-cycle toxicity tests  have  been  conducted  with   the  freshwater midge



(Paratanytarsus sp.) and the saltwater mysid (M. bahia) (Table 3-1) and early  life stage  tests




have been conducted with the fathead minnow (Pimephales promelas) and sheepshead minnow



(Cyprinodon variegatus) (Table 3-1). For each of these species, except for P. promelas. one or




more benthic life stages were exposed to acenaphthene.  Other chronic toxicity tests have been
                                         3-3

-------
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                D Other Invertebrates
                O  Fishes
                             Neanthes (X)
                               Annelid
                                                                             Arbacia (E)
                                                                             Sea urchin
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  Amphipod
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                                Mysid
                 Crangon (X)
                Sand shrimp
        100
                          20
     40
60
                                                                     80
                                                100
                          PERCENTAGE RANK OF SALTWATER GENERA
  Figure 3-2.   Genus mean acute values from water only acute toxicity tests using saltwater
               species vs.  percentage rank of their sensitivity.  Symbols representing  benthic
               species are  solid,  those representing water column species are open.  Asterisks
               indicate greater than values.  E = embryo, J = juvenile.
                                            3-4

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 conducted with these two freshwater species (Lemke,  1984;  Lemke et al.,1983;  Leinke and




 Anderson,  1984) but insufficient documentation is available to permit use of these results



 (Thursby, 1991a).




    Two acceptable life cycle toxicity tests have been conducted with  Paratanytarsus sp.



 (Northwestern Aquatic Sciences, 1981). In the first test there was a 59% reduction in growth




 and an 85 % reduction in reproduction in 575 /tg/L relative to control animals (Table 3-2). Eggs



 produced by animals in this first test failed to hatch at 575 /*g/L. There was no significant effect




 on parents or egg hatchability in acenaphthene concentrations from 32 to 295 /tg/L.  In the




 second test with Paratanytarsus sp. there was a 21 % reduction in survival in 315 /tg/L relative




 to control animals; egg  hatchability was not affected at the highest concentration  tested (676



 jKg/L);  although survival  of hatched  Paratanytarsus sp.  larvae was reduced 64% in this



 concentration.




     A total of six early  life-stage toxicity tests have been conducted with the P. promelas part



 of  a  round-robin test series;  two  each from three laboratories  (Table  3-2).   The  effect



 concentrations across laboratories and  tests  ranged from  98  to 509 /*g/L, a factor of 5.2.



 Growth (dry weight), survival or both growth and survival were reduced.  Only one of these test



pairs had a suitable measured acute value, allowing calculation of an acute-chronic ratio (Cairns




and Nebeker, 1982). The concentration-response relationships were similar for these two tests.



Parental fish were unaffected in the first test at acenaphthene concentrations ranging from 67 to




332 jfg/L, while fish exposed to 495 /xg/L had a 54% reduction in  growth relative to control



fish.  In the second  test, Cairns and Nebeker (1982)  observed a 30% reduction in growth in



parental fish in 509 jtg/L while there was no effect on fish exposed  to 197 to 345  /*g/L.
                                          3-7

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    Data from three saltwater chronic toxicity tests are available, two with M- bahia and one
                                                                          «
 with (£. variegatus. M. bahia reproduction was affected by acenaphthene in two tests from two

 different laboratories.  In the first test (Home et al., 1983) there  was a 93% decrease  in

 reproduction in 340 /tg/L relative to control M- bahia: all M- bahia in 510 /tg/L died. No

 effects were observed at 100 or 240 /tg/L in the parental generation,  and juveniles released in

 >. 340 /ig/L were not affected.  In the second test (Thursby et al.,  1989b) there was  a 34%

 decrease in growth in 168 /tg/L and 96% increase in mortality at 354  /tg/L.  There was a 91 %

 decrease in reproduction in M. bahia exposed to 91.8 /tg/L and M- bahia exposed to 168 and

 354 /tg/L did not reproduce.  M- bahia exposed to _<. 44.6 /tg/L were not affected.

     £_.. variegatus exposed to acenaphthene in an early life stage test  (Ward et al., 1981) were

 affected at acenaphthene concentrations of _>.970 /tg/L (Table 3-2). There was a 70% reduction

 in survival of fish hatched in 970 /tg/L.  Fewer than 10% of the embryos at  >_ 2,000 /tg/L

 hatched and all fish that hatched died.  There was no effect on either survival or growth in fish

 exposed to 240 or 520 /tg/L.

       The difference between acute and chronic toxicity of acenaphthene is small (Table 3-2).

 Species mean acute-chronic ratios are 1.475 for P. promelas.  3.424 for M. bahia. 4.365 for C.

variegatus and 6.683 for Paratanytarsus sp.  The final ACR,  the geometric mean of these four

values, is 3.484.

       The FCV (Table 3-2) are used as the effect concentrations for calculating the SQC for

protection of bentbic species.  The FCV for freshwater organisms of 22.96 /tg/L is the quotient

of the  FAV of 80.01 /tg/L and the final ACR of 3.484.  Similarly, the FCV for saltwater

organisms of 40.41 /tg/L is the quotient of the FAV of 140.8 /tg/L and the final ACR of 3.484.
                                         3-10

-------
3.4 APPLICABILITY OF THE WATER QUALITY CRITERION AS THE EFFECTS
   CONCENTRATION FOR DERIVATION OF THE ACENAPHTHENE SEDIMENT
   QUALITY CRITERION:

       The use of the FCV (the  chronic effects-based WQC concentration) as the  effects

concentration for calculation  of the EqP-based SQC assumes  that benthic (infaunal and

epibenthic) species, taken as a group, have sensitivities similar to all benthic and water column

species tested to derive the WQC concentration.  Data supporting the reasonableness  of this

assumption over all chemicals for which there are published or draft WQC documents are

presented in Di Toro et al. (1991), and the SQC Technical Basis Document U.S. EPA (1993a).

The conclusion of similarity of sensitivity is supported by comparisons between (1) acute values

for the most sensitive benthic and acute values for the most sensitive water column species for

all chemicals; (2) acute values for all benthic species and acute values for all species  in the

WQC documents across all chemicals after standardizing the LC50 values; (3)  FAVs calculated

for benthic species alone and FAVs calculated for all species in the WQC documents; and (4)

individual chemical comparisons of benthic species vs. all species.  Only in this last comparison

are acenaphthene-specific comparisons in sensitivity of benthic and all (benthic and  water-

column) species conducted. The following paragraphs examine the data on  the similarity of

sensitivity of benthic and all species for acenaphthene.

       For acenaphthene, benthic species account for 4 out of 10 genera tested in freshwater,

and 6 out of 10 genera tested in  saltwater (Figures 3-1, 3-2).  An initial test  of the difference

between the freshwater and saltwater FAVs for all species (water column and  benthic) exposed

to acenaphthene was performed using the Approximate Randomization method (Noreen,  1989).
                                        3-11

-------
 The Approximate Randomization method tests the significance level of a test statistic when



 compared to a distribution of statistics generated  from many random subsamples.  The test



 statistic in this case is the difference between the freshwater FAV, computed from the freshwater



 (combined water column and benthic) species LC50 values, and the saltwater FAV, computed



 from the saltwater (combined water column and benthic) species LC50 values (Table 3-1).  In




 the Approximate Randomization method, the freshwater LC50 values and the saltwater LC50



 values are combined into one data set.  The data set is shuffled, then separated back so that




 randomly generated "freshwater" and "saltwater" FAVs can be computed.  The LC50 values




 are separated back such that the number of LC50 values used to calculate the sample FAVs are




 the same as the number used to calculate the original FAVs. These two FAVs are subtracted



 and the difference used  as the sample statistic. This is done many times so that the sample



 statistics  make up a distribution  that is representative of the population of FAV differences



 (Figure 3-3).  The test statistic  is compared to this distribution to determine it's level of



 significance.   The null  hypothesis is that the LC50 values that comprise the saltwater and




freshwater data bases are not different.  If this is true,  the difference  between the actual




freshwater and saltwater FAVs should be common to the majority of randomly generated FAV




differences.  For acenaphthene, the test-statistic falls at the 33 percentile of the generated FAV



differences.  Since the probability is less than 95%, the hypothesis of no significant difference



in sensitivity for freshwater and saltwater species is accepted (Table 3-3).



       Since freshwater and saltwater species showed similar sensitivity, a test of difference in



sensitivity for benthic and all (benthic and water column species combined, hereafter referred




to as "WQC") organisms combining freshwater and saltwater species using the Approximate
                                        3-12

-------
        600
        800
                 ACENAPHTHENE
                         I  I  I  I  I—T
 Bil
     -  FRESHWATER VS SALTWATER
                                                           99.9
 LU
 O
 IU
 u.
 u.
 5'
 600
 600
 400
 300
 200
 100
  0
 -100
-200
-300
-400
-500
       -600
             TTT
I I I III!
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            -  BENTHC VS WQC
                                                      iCEOO O~
             ' niiim  i i i MIIII    i
                                              mi"
                                                Illllll
          0.1
                  10  20
               60
          80  90
       99
99.9
                            PROBABILITY
Figure 3-3.
   Probability distribution of FAV difference statistics to compare water-only data
   from freshwater vs. saltwater (upper panel) and benthic vs. WQC (lower panel)
   data.                                                   '
                              3-13

-------
             TABLE 3-3. RESULTS OF APPROXIMATE RANDOMIZATION TEST FOR
             THE EQUALITY OF THE FRESHWATER AND SALTWATER-LC50
             DISTRIBUTIONS FOR ACENAPHTHENE AND APPROXIMATE
             RANDOMIZATION TEST FOR THE EQUALITY OF BENTHIC AND
             COMBINED BENTHIC AND WATER COLUMN  (WQC) LC50
                                DISTRIBUTIONS.

             Compar-
             ison      Habitat or Water Type'   AR Statistic"    Probability"

             Fresh    Fresh (10)   Salt (10)       -59.04         33
             vsSalt

             Benthic   Benthic (10) WQC (20)      -41.34        31
             vs Water
             Column +
             Benthic (WQC)
            •Values in parentheses are the number of LC50 values used in the comparison.
            bAR statistic = FAV difference between original compared groups.
            Tr(AR statistic theoretical ^ AR statistic observed) given that the samples
             came from the same population.
Randomization method was performed.  The test statistic in this case is the difference between

the WQC FAV, computed from the WQC LC50 values, and the benthic FAV, computed from

the benthic organism LC50 values.  This is slightly different then the previous test for saltwater

and freshwater species.  The difference is that saltwater and freshwater species represent two

separate groups.  In this test the benthic organisms are a subset of the WQC organisms set.  In

the Approximate Randomization method for this test, the number of data points coinciding with

the number of benthic organisms are selected from the WQC data set. A "benthic" FAV is

computed.  The original WQC FAV and the  "benthic" FAV are then used to compute the

difference statistic.  This is done many tunes and the distribution that results i representative

                                      3-14

-------
representative of the population of FAV difference statistics.  The test statistic is compared to
                                                                        #
this distribution  to determine its  level of significance. The probability distribution  of  the

computed FAV differences are shown in the bottom panel of Figure 3-3. The test statistic  for

this analysis falls at  the 31 percentile and the hypothesis of no difference in sensitivity is

accepted (Table 3-3).  This analysis suggests that the FCV for acenaphthene based on data from

all tested species is an appropriate effects concentration for benthic organisms.
                                        3-15

-------

-------
                                     SECTION 4

           TOXICITY OF ACENAPHTHENE (ACTUAL AND PREDICTED):
                              SEDIMENT EXPOSURES
4.1 TOXICITY OF ACENAPHTHENE IN SEDIMENTS:

       The toxicity of acenaphthene spiked into sediments has been tested with two saltwater

amphipod species.  Freshwater benthic species have not been tested in acenaphthene-spiked

sediments.  All concentrations of acenaphthene in sediments or interstitial water where effects

were observed in benthic species  (Table 4-1) are greater than SQC or FCV concentrations

reported in this document. Details about exposure methodology are provided because, unlike

aquatic toxicity  tests,   sediment testing  methodologies   have  not  been  standardized.

Generalizations across species or sediments  are limited because of the limited number of

experiments. Therefore, insights into relative sensitivities of aquatic species to acenaphthene can

only be obtained from results of water-only tests (Section 3). Data are available from many

experiments using both field and laboratory sediments contaminated with mixtures of PAHs and

other compounds which include acenaphthene. Data from these studies have not been included

here because it is not possible to determine the contribution of acenaphthene to the observed

toxicity.

       Swartz  (1991) exposed the  amphipods Eohaustorius estuarius  and Leptocheirus

plumulosus to  three acenaphthene-spiked sediments with total organic carbon content (TOC)

ranging from 0.82 to 4.21 %.  Sediments were  rolled (1) for four hours in acenaphthene-coated
                                         4-1

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bottles,  (2) stored at 4°C for either 72 hours (experiments with R  estuarius') or overnight
                                      ,              F ,                      •*
(experiments with L.. plumulosus). (3) rolled for an additional four hours, and (4) then stored

for 7 days at 4°C.  The 10-day LCSO's for both species increased slightly with increasing


organic  carbon concentration when  the acenaphthene concentration was expressed on  a dry


weight basis, but decreased for E. estuarius and no pattern was apparent for L. plumulosus when


concentration was  expressed on an organic carbon basis.   LCSO's normalized to dry weight

differed by less than a factor of 1.5 (44.4 to 68.4 /*g/g) for R  estuarius and less than a factor

of 1.9 for L.. plumulosus over a 5.3-fold range of TOC.  The organic carbon normalized LCSO's


for R estuarius differed by a factor of 2.7 (1,630 to 4,330 /tg/goc) wnile for L- plumulosus they


differed by a factor of  > 3.0 (7730  to > 23,500 Aig/goc).

      Overall, the need for organic carbon normalization of the concentration of nonionic


organic chemicals in sediments is presented in the SQC Technical Basis Document (U.S. EPA,


1993a).  The need for organic carbon normalization for acenaphthene is somewhat supported by
                                                                                 »
the results of spiked-sediment toxicity tests described above.  Although  it is important to

demonstrate that organic carbon normalization is necessary if SQC are to be derived using the


EqP approach, it is fundamentally more important to demonstrate that KQC and water only effects

concentrations can be used to predict effects concentrations for acenaphthene  and other nonionic


organic chemicals on an organic carbon basis for a range of sediments. Evidence supporting this

prediction for acenaphthene and other nonionic organic chemicals follows in Section 4.3.
4.2 CORRELATION BETWEEN ORGANISM RESPONSE AND PORE WATER
   CONCENTRATION:

       One corollary of the EqP theory is that pore-water LCSO's for a given organism should
                                          4-3

-------
be constant across sediments of varying organic carbon content (U.S. EPA, 1993a). Appropriate




pore-water LC50 values are available for two bentMc species (Table 4-2). Swartz (1991) found



10-day LC50 values based on pore-water concentrations varied by a factor of 1.5 (542 to 800



pg/L) for IL estuarius and by a factor of >  1.2 (1,410 to >  1,720 /*g/L) for L. plumulosus.



This variability is somewhat less than that shown when either dry weight (factors of 1.5 and 1.9)




or organic carbon (factors of 2.7 and 3.0) normalization are used to determine LCSOs based on



acenaphthene concentration in sediments.



     A more detailed evaluation of the degree to which the response of benthic organisms can



be predicted from toxic units of substances in pore water can be made utilizing results from



toxicity tests  with sediments  spiked  with other substances,  including acenaphthene and



phenanthrene (Swartz,  1991), endrin (Nebeker et al., 1989; Schuytema et al., 1989),  dieldrin




(Hoke, 1992), fluoranthene (Swartz et al., 1990, De Witt et al., 1992), or kepone (Adams et al.,



1985) (Figure 4-1; Appendix B). The data included in this analysis come from tests conducted




at EPA laboratories or from tests which utilize designs at least as rigorous as those conducted



at the EPA laboratories.  Tests with acenaphthene and phenanthrene used  two saltwater



amphipods (L. plumulosus and JL estuarius) and marine sediments. Tests with fluoranthene used



the saltwater amphipod (Rhepoxynius abronius) and marine sediments.   Freshwater sediments




spiked with endrin were  tested using  the amphipod Hyalella azteca: while the midge,



Chironomus tentans.  was  tested using kepone-spiked sediments.   Figure 4-1 presents the




percentage mortalities of the benthic species tested in individual treatments for each chemical



versus "pore water toxic units" (PWTUs) for all sediments tested. PWTUs are the concentration




of the chemical in pore water (/tg/L) divided by the water only LC50 (/tg/L).  Theoretically,
                                          4-4

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50% mortality should occur at one interstitial water toxic unit.  At concentrations below one
                                                                         *
PWTU there should be less than 50% mortality, and at concentrations above one PWTU there

should be greater than 50% mortality.  Figure 4-1 shows that at concentrations below one

PWTU mortality was  generally  low, and increased  sharply at approximately one PWTU.

Therefore, this comparison supports the concept that interstitial water concentrations can be used

to predict the response of an organism to a chemical that is not sediment-specific.  This pore

water normalization was not used to derive SQC in this document because of the complexation

of nonionic organic chemicals with pore water DOC (Section 2) and the difficulties of adequately

sampling pore waters.  Data from the dieldrin experiments  (Hoke and Ankley, 1991) are not

included because more knowledge of the pore water DOC will be required because dieldrin has

a high KQC value.
4.3 TESTS OF THE EQUILIBRIUM PARTITIONING PREDICTION OF SEDIMENT
       TOXICITY:
       SQC derived using the EqP approach utilize partition coefficients (Koc) and FCV from

WQC documents to derive the SQC concentration for protection of benthic organisms. The KQC

is used to normalize sediment concentrations and predict biologically available concentrations

across  sediment types.   The data required to test the organic carbon normalization  for

acenaphthene in sediments are available for four benthic species.  Data from tests with water

column species were not included in this analysis. Testing of this component of SQC derivation

requires three elements: (1) a water-only effect concentration, such as a 10-day LC50 value in

ftg/L, (2) an identical sediment effect concentration on an organic carbon basis, such as a 10-day

LC50 value in /wg/goc, and (3) a partition coefficient for the chemical, KQC in L/Kgoc. This

                                         4-7

-------
section presents evidence that the observed effect concentration in sediments (2) can be predicted




utilizing the water effect concentration (1) and the partition coefficient (3).



      Predicted 10-day LC50 values from acenaphthene-spiked sediment tests on a Mg/goc basis



with IL estuarius and L.. plumulosus were calculated (Table 4-2) using the log10KoC value of 3.78



from Section 2 of this document and the sediment LCSOs in Swartz (1991).  Ratios of actual to




predicted LC50s for acenaphthene averaged 1.11 (range 0.76 to 2.01) for R estuarius and 3.25



(range 1.98 to >6.02) for ^ plumulosus.   The overall mean for both species was 190.



      A more detailed evaluation of the accuracy and precision of the EqP prediction of the



response of benthic organisms can be made using the results of toxicity tests with amphipods



exposed to sediments spiked with acenaphthene, phenanthrene, dieldrin, endrin, or fluoranthene.



The data included in this analysis came from tests conducted at EPA laboratories or from tests




which utilized designs at  least as rigorous as those conducted at the EPA laboratories.  Data



from the kepone experiments are not included because a measured KQW obtained using the slow-




stir flask method is not available. Swartz (1991) exposed the saltwater amphipods R estuarius



and LJ. plumulosus to acenaphthene in three marine sediments having organic carbon contents



ranging from 0.82 to 4.2%   and  to phenanthrene in  three marine sediments having organic



carbon contents ranging  from 0.82 to 3.6%..  Swartz et al. (1990) exposed the saltwater




amphipod JR.. abronius to fluoranthene in three marine  sediments having 0.18, 0.31 and 0.48%



organic carbon.  Hoke and Ankley (1991) exposed the amphipod H.  azteca to three dieldrin-




spiked freshwater sediments having 1.7, 3.0 and 8.5% organic carbon and Hoke (1992) exposed



the midge £L. tentans to  freshwater dieldrin spiked sediments having 2.0 and 1.5% organic



carbon.  Nebeker et al. (1989) and Schuytema et al. (1989) exposed H. azteca to three endrin-
                                         4-8

-------
spiked sediments having 3.0, 6.1 and 11.2% organic carbon.  Figure 4-2 presents the percentage




mortalities of amphipods in individual treatments of each chemical versus "predicted sediment




toxic units" (PSTU) for each sediment treatment. PSTUs are the concentration of the chemical




in sediments 0*g/goc) divided by the predicted LC50 0*g/goc)m sediments (the product of KQC



and the 10-day water-only LC50).  In this normalization, 50% mortality should occur at one




PSTU.  At concentrations below one PSTU mortality was generally low, and increased sharply



at one PSTU. The means of the LCSOs for these tests calculated on a PSTU basis were 1.90,




for acenaphthene, 1.16 for dieldrin,  0.44 for  endrin,  0.80 for fluoranthene and 1.22 for




phenanthrene. The mean value for the five chemicals is 0.99.   This illustrates that the EqP




method can account for the effects of different sediment properties and properly predict the



effects concentration in sediments using the effects concentration from water only exposures.
                                          4-9

-------
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                  4-10

-------
                                    SECTION 5








                  CRITERIA DERIVATION FOR ACENAPHTHENE








5.1 CRITERIA DERIVATION:



      The water quality criteria (WQC) Final Chronic Value (FCV), without an averaging




period or return frequency (See section 3), is used to-the calculate the sediment quality criteria




(SQC) because it is probable that the concentration of contaminants in sediments are relatively



stable over time, thus exposure to sedentary benthic species should be chronic and relatively




constant.  This is in  contrast to the situation  in the water column,  where a rapid change in




exposure and  exposures  of limited  durations  can occur  due to fluctuations  in  effluent




concentrations dilutions in receiving waters or the free-swimming or planktonic nature of water



column organisms. For some particular uses of the SQC it may be appropriate to use the area!




extent and vertical stratification of contamination of a sediment at a site in much the same way



that averaging periods are mixing zones used WQC.




      The FCV is the value that should protect  95% of the tested species included in the




calculation of the WQC from chronic effects of the substance.  The FCV is the quotient of the



Final Acute Value (FAV), and the Final Acute Chronic Ratio (ACR) for the substance.  The



FAV is an estimate of the acute LC50 or EC50 concentration of the substance corresponding to



a cumulative probability of 0.05 for the genera from eight or more families for which acceptable







                                        5-1

-------
acute tests have been conducted on the substance.  The ACR is the mean ratio of acute to



chronic toxicity for three or more species exposed to the substance that meets minimum database



requirements.  For more information on the calculation of ACRs, FAVs, and FCVs see the



National Water Quality Criteria Guidelines (Stephan et al., 1985).   The FCV used in this



document differs from the FCV in the acenaphthene WQC document (U.S. FJ*A, 1980) because




it incorporates recent data not included in that document, and omits some data which does not



meet the data requirements established in the WQC Guidelines (Stephan et al., 1985).




       The equilibrium partitioning (EqP) method for calculating SQC is based on the following



procedure.  If FCV fyig/L) is the chronic concentration from the WQC for the chemical of



interest,  then the SQC Otg/g  sediment), is computed using the partition coefficient, KP (L/g



sediment), between sediment and pore water:




             SQC = KP FCV                                                 (5-1)



       Since organic carbon is the predominant sorption phase for conionic organic chemicals



in naturally occurring sediments, (salinity, grainsize  and other sediment parameters have



inconsequential roles  in  sorption,  see  sections 2.1  and 4.3) the  organic  carbon partition



coefficient, (K^ can  be substituted for KP. Therefore, on a sediment organic carbon basis,




SQCOC Og/goc), is:



             SQCoc = KOC FCV                                              (5-2)



Since (Koc) is presumably independent of sediment type for non-ionic organic chemicals, so also



is SQCoc. Table 5-1 contains the calculation of the acenaphthene SQC.



       The organic carbon normalized SQC is applicable to sediments with an organic carbon



fraction of foe ^  0.2%.  For sediments with foe  < 0.2%, organic carbon normalization and
                                         5-2

-------
 SQC may not apply.
        TABLE 5-1. SEDIMENT QUALITY CRITERIA FOR ACENAPHTHENE.
Type of
Water Body
Fresh Water
Salt Water
(L/kg) W
3.83
3.83
LogioKoc
(L/kg)
3.76
3.76
FCV
23.0
40.4
Otg/goc)
130
230
     aSQCoc = (103'76 L/kgoc)»(10-3 kgoc/goc)»(23.0 /*g acenaphthene/L) = 130 /tg
           acenaphthene/goc
     bSQCoc = (103-76 L/kgoc)«(10-3 kgoc/goc)«(40.4Mg acenaphthene/L) = 230 pg
             acenaphthene/goc

       Since organic carbon is the factor controlling the bioavailability of nonionic organic

compounds in sediments, SQC have been developed on an organic carbon basis, not on a dry

weight basis.  When the chemical concentrations  in  sediments are reported as dry weight

concentration and  organic carbon  data  are  available, it  is best to convert the  sediment

concentration to fig chemical/gram organic carbon.  These concentrations can then be directly

compared to  the  SQC value.   This  facilitates comparisons  between the SQC  and  field

concentrations  relative  to  identification  of hot spots and the  degree to  which  sediment

concentrations do or do not exceed SQC values.  The conversion from dry weight to organic

carbon normalized concentration can be done using the following formula:

       jug Chemical/goc =  A*g Chemical/gDRy ^ + (% TOC -s- 100)

                       = jug Chemical/gDRYWT •  100 •*• % TOC

       For example, a freshwater sediment with a concentration of 6.00 jig chemical/gDRY m
                                        5-3

-------
 and 0.5 % TOG has an organic carbon-normalized concentration of 1,200 /*g/goc (6.00 /*g/gDRYWT




 • 100 -^ 0.5  = 1,200 Atg/goc) which exceeds the SQC of 130 jig/goc-  Another freshwater



 sediment with the same concentration of  acenaphthene (6.00  /tg/gDRY wr)  but  a TOC



 concentration of 5.0% would have an organic carbon normalized concentration of 120 pcg/goc



 (6.00 /tg/gDRY wr * 100 •* 5.0 = 120 /tg/goc), which is below the SQC for acenaphthene.



       In situations where TOC values for particular sediments are not available, a range of



 TOC values may be used in a "worst  case" or "best case" analysis. In this case, the organic



 carbon-normalized SQC values (SQCoc) may be "converted" to dry weight-normalized SQC



 values (SQCDRY vr.). This "conversion" must be done for each level of TOC of interest:




             SQCDRYWT =  SQCocOtg/goc) • (% TOC -^ 100)




 where SQCDRYWT is the dry weight normalized SQC value.  For example, the SQC value for



 freshwater sediments with 1% organic carbon is 1.3 jtg/g:




              SQCDRYWT. =  130 /tg/goc • 1% TOC H- 100 = 1.3 ftg/goRYwr



 This method is used in the analysis of the STORET data in section 5.4.








5.2 UNCERTAINTY ANALYSIS:




    Some of the uncertainty in the calculation of the acenaphthene SQC can be estimated from




the degree to which the EqP model,  which is the basis for the criteria, can rationalize the




available sediment toxicity data.  The EqP model asserts that (1) the bioavailability of nonionic



organic chemicals from sediments is equal on an organic carbon basis; and (2) that the effects



concentration in sediment (/tg/goc) can be estimated from the product of the effects concentration



from water-only  exposures 0*g/L) and the partition coefficient KQC (L/kg).  The uncertainty






                                        5-4

-------
associated with the SQC can be obtained from a quantitative estimate of the degree to which the




available data support these assertions.




    The data used in the uncertainty analysis are from the water-only and sediment toxicity tests




that have been conducted fulfill the minimum database requirements for the development of SQC




(see Section 4.3 and Technical Basis Document, U.S. EPA 1993a). These freshwater and




saltwater tests span a range of chemicals and organisms; they include both water-only and



sediment exposures, and they are replicated within each chemical - organism - exposure media




treatment.  These data were analyzed using an analysis of variance (ANOVA) to estimate the



uncertainty (i.e. the variance) associated with varying the exposure media and that associated




with experimental error. If the EqP model were perfect, then there would be only experimental



error.  Therefore, the uncertainty associated with the use of EqP is the variance associated with



varying exposure media.




    The data used in the  uncertainty analysis are illustrated in Figure 4-2.  The data  for




acenaphthene are summarized in Appendix B. LCSOs for sediment and water-only tests were



computed from these data. The EqP model can be used to normalize the data in order to  put




it on a common basis.  The LCSOs from water-only exposures (LC50W; ftg/L) are related to the




organic carbon-normalized LCSOs  from sediment exposures  (LC50S(OC; /tg/goc) via  the



partitioning equation:








             LC50S,OC = KocLC50w                                     (5-3)








The EqP model asserts that the toxicity of sediments expressed on an organic carbon basis equals







                                         5-5

-------
the toxicity in water tests multiplied by the KQC.  Therefore, both LC50SjOC and Koc*LC50w



are estimates  of the true LC50oc £°r each chemical-organism pair.   In  this analysis,  the



uncertainty of KQC is not treated separately.  Any error associated with KQC will be reflected in



the uncertainty attributed to varying the exposure media.



    In order to perform an analysis of variance, a model of the random variations is required.




As discussed above, experiments that seek to validate equation 5-3 are subject to various sources



of random variations. A number of chemicals and organisms have been tested. Each chemical-



 organism pair was tested in water-only exposures and in different sediments.  Let a represent




the random variation due to this source. Also, each experiment is replicated.  Let G represent



the random variation due to this source. If the model were perfect, there would be no random



variations other than that due to experimental error which is reflected in the replications.  Hence



a represents the uncertainty due to the approximations inherent in the model and e represents



the experimental error.  Let (
-------
 makie these estimates (U.S. EPA, 1993a). The results are shown in Table 5-2.
             Table 5-2: ANALYSIS OF VARIANCE FOR DERIVATION OF
             SEDIMENT QUALITY CRITERIA CONFIDENCE LIMITS
             FOR ACENAPHTHENE.
Source of Uncertainty
Exposure media
Replication
Sediment Quality Criteria
Parameter
0*g/goc)
°«
«e
a
°SQC
Value
0.39
0.21
0.39
The last line of Table 5-2 is the uncertainty associated with the SQC; i.e., the variance

associated with the exposure media variability.

    The confidence limits for the SQC are computed using this estimate of uncertainty for SQC.

For the 95% confidence interval limits, the significance level is 1.96 for normally distributed

errors.  Hence:

                          = ln(SQCoc) + 1.96aSQC                             (5-5)

                            = ln(SQCoc) - 1.96_ 0.2 %  For sediments with foe < 0.2 % , organic carbon normalization does not


                                       5-7

-------
 apply and the SQC do not apply.
               TABLE "3. SEDIMENT QUALITY CRITERIA
                   CGKrIDENCE LIMITS FOR ACENAPHTHENE
                                  Sediment Quality Criteria

                                   95% Confidence Limits
                   Type of
                 Water Body    MS/Soc       Lower Upper


                 Freshwater    130         62    280

                 Saltwater     240         110   500



5.3 COMPARISON OF ACENAPHTHENE SQC AND UNCERTAINTY
CONCENTRATIONS TO SEDIMENT CONCENTRATIONS THAT ARE TOXIC OR
PREDICTED TO BE CHRONICALLY ACCEPTABLE.

      Insight into the magnitude of protection  afforded to benthic  species by  SQC

concentrations and 95 %  confidence intervals can be determined from effect concentrations from

toxicity tests with benthic species exposed to sediments spiked with acenaphthene and sediment

concentrations predicted to be chronically safe to organisms tested in water-only exposures

(Figure 5-1; 5-2). Effect concentrations in sediments can be predicted from water-only toxicity

data and KOC values (See Section IV). Acute-chronic ratios (ACRs) are used to extrapolate from

Genus Mean Acute Values (GMAV) from water-only  96-hour lethality tests to  chronically

acceptable concentrations.  Therefore,  it may be  reasonable  to predict for acenaphthene

chronically acceptable  sediment  concentrations (Predicted Genus Mean  Chronic  Value

(PGMCV)) from GMAVs (Appendix A), ACRs (Table 3-3) and the KQC (Table 5-1):

            PGMCV  = (GMAV  -^ ACR)«KoC

                                      5-8

-------
               105
           o
           o
          IU
          O

          O
          et
UJ
s
CO

UJ
O
Q

g
5
UJ
£
               104
               103
               102
               10
               Water-only tests: (96HR LC50+ ACR) KQC

               A Arthropods
               D Other Invertebrates
               O Rshes
                  Log10Koc»3-76
                 ACR »3.48
                                                          upper: 280 ng/goe
                                                          k3wer:62Mg/goc
                             20
                              40
60
80
100
                          PERCENTAGE RANK OF FRESHWATER GENERA
Figure 5-1.   Comparison between SQC concentrations and 95% confidence intervals, effect
            concentrations from benthic organisms exposed to acenaphthene-spiked sediments
            and  sediment concentrations predicted to be chronically safe in fresh water
            sediments.  Concentrations predicted to be chronically safe (Predicted Genus
            Mean Chronic Values, PGMCV) are derived from the Genus Mean Acute Values
            (GMAV) from water-only 96-hour lethality tests, Acute Chronic Ratios (ACR)
            and KQC values. PGMCV = (GMAV -*• ACR)Koc. Symbols for PGMCVs are A
            for arthropods, O for fishes and D for other invertebrates.  Solid symbols are
            benthic genera; open symbols water column genera. Arrows indicate greater than
            values.  Error bars around sediment LC50 values indicate observed range of
            LC50s.
                                       5-9

-------
            105P
     o
     o
     0)
    Ul

    5
    O
    §
    tr
    o
    z
    I
    CO
    z
    UI
    o
    Q
    UJ
    5
    5
    UJ
    E
104
103
102
             10
            Water-only tests: (96HR LC50 •«• ACR) KQC

         A Arthropods
         D Other Invertebrates
         O Rshes
ACR = 3.48
Sediment Tests: IQdLCSO
*£, estuarlus » 2384 fig/Qoc
  range 3 tests -1630 -4330
® L. plumulosus « 12671
  range 3 tests -7730 - 723500
                                                             a
                                   upper:

                                   SQC:

                                   lower:
                            20
                            40
                            60
80
100
                       PERCENTAGE RANK OF SALTWATER GENERA
Figure 5-2.   Comparison between SQC concentrations and 95% confidence intervals, effect
             concentrations from benthic organisms exposed to acenaphthene-spiked sediments
             and  sediment concentrations  predicted  to be chronically safe  in  salt water
             sediments.  Concentrations predicted to be chronically safe (Predicted Genus
             Mean Chronic Values, PGMCV) are derived from the Genus Mean Acute Values
             (GMAV) from water-only 96-hour lethality tests, Acute Chronic Ratios (ACR)
             and KOC values. PGMCV = (GMAV -^  ACR)Koc.  Symbols for PGMCVs are
             A for arthropods, O for fishes and D for other invertebrates.  Solid symbols are
             benthic genera; open symbols water-column genera. Arrows indicate greater than
             values.  Error bars around sediment LC50 values indicate  observed range of
             LC50s.
                                      5-10

-------
       Each predicted PGMCV for tested fishes » , arthropods A or other invertebrates • is
                                                                           *
plotted against the percentage rank of its sensitivity.  Results from toxicity tests with benthic

organisms  exposed to sediments spiked with acenaphthene (Table 4-1) are placed  in the

PGMCV rank appropriate to the test-specific effect concentration.  (For example, the 10-day

LC50 for E. estuarius (2,384 /*g/goc) is placed between the PGMCV of  1,858 /Kg/goc for the

amphipod,  Leptocheirus.  and the PGMCV of 5,120 jtg/goc for the  minnow, Cyrmnodon.)

Therefore,  LC50 or other effect concentrations  are  intermingled in this  figure  with

concentrations predicted to be  chronically safe.  Care  should  be taken by the reader in

interpreting these data with dissimilar endpoints. The following discussion of SQC,  organism

sensitivities and PGMCVs is not intended to provide accurate predictions of the responses of taxa

or communities  of benthic organisms  relative to specific concentrations of acenaphthene in

sediments in the field. It is, however, intended to guide scientists and managers through the

complexity of available data relative to potential risks  to benthic taxa posed by sediments

contaminated with acenaphthene.

       The freshwater SQC for acenaphthene (130 /tg/goc) is less than any of the PGMCVs.

PGMCVs for 9 of 10 freshwater genera are greater than the upper 95% confidence interval of

the SQC (280 Mg/goc)-  The PGMCVs for the cladoceran Daphnia (198  /*g/goc) is below the

SQC upper 95% confidence interval.  This suggests that  if the extrapolation  from water only

acute lethality tests  to  chronically acceptable  sediment  concentrations  is accurate, this or

similarly sensitive genera may be chronically impacted by sediment concentrations marginally

above the SQC and possibly less than the 95 % upper confidence interval.  For acenaphthene,

the PGMCVs range over an order of magnitude from the most sensitive to the most tolerant
                                         5-11

-------
genus.  Chronic effect concentrations may, however, occur at concentrations below saturation.
                                                                      <•«

A sediment concentration four times the SQC would include the PGMCVs of two of the three


benthic genera tested including  stoneflies, and  amphipods.   The tolerant benthic midge


Paratanytarsus might be expected to not be chronically impacted in sediments with acenaphthene


concentrations 25X the SQC.


      The saltwater SQC for acenaphthene (230 /ig/goc) is less than any of the PGMCVs or


LC50 values from spiked sediment toxicity tests.  The PGMCV for the sand shrimp Crangon


septemspinosus (404 /tg/goc) is lower than the upper 95 % confidence interval for the SQC.  For


acenaphthene, PGMCVs from the most sensitive to the most tolerant saltwater genus range over


an order of  magnitude.  A sediment concentration five times the SQC would include the


PGMCVs of one-half of the six benthic genera tested including three arthropod genera.  Other


genera of benthic arthropods, polychaetes, and fishes are less sensitive. Data from lethality tests


with two  saltwater amphipods, Eohaustorius and Leptocheirus. exposed to acenaphthene spiked


into sediments substantiates this projection; the 10 day LCSOs from these tests range from 10


to 40 times the SQC of 230 /tg/goc-




5.4 COMPARISON OF ACENAPHTHENE SQC TO STORET AND STATUS AND
    TRENDS DATA FOR SEDIMENT ACENAPHTHENE:


      A STORET (U.S. EPA, 1989a) data retrieval was performed to obtain a preliminary


assessment of the concentrations of acenaphthene in the sediments of the nation's water bodies.


Log probability plots of acenaphthene concentrations on a dry weight basis in sediments since


1986 are shown in Figure 5-3. Acenaphthene is found at detectable concentrations in sediments


from rivers, lakes and near coastal water bodies in the United States. Median concentrations are


                                       5-12

-------
Figure 5-3.
10 •
10 *
10 1
10 °
10 -1
10 •*
10 "•
10 "*
0.
10 4
10 •
10 *
10 1
10 °
10 -1
10 •*
10 •"
10 •*
I STREAM TOTAL SAMPLES: 681* ' ' ~" ""m-iT-i — I""" ' ' i
MEASURED SAMPLES: 53 -
< .
ir^ ^
M:«««l£«£<«&^ ]
• ( ]
11 » 20 60 80 90 ' 96 	 M
r LAKE TOTAL SAMPLES: 56 ' ' ' ' l""" ' '' "l1"" '.•
MEASURED SAMPLES: 5
"--1 ~ 	 ~ "• ~^— :
<^*<<<<*< ~~* J
i i iimii f, *. «,*Air*f * ff**ffe. i . . i IT,,... 	


\A



                                                 60
                                             80  90
                                                                       89     99A
          ESTUARY
                                 TOTAL SAMPLES: 74
                                 MEASURED SAMPLES: 4
                                                                    i  i  IHIIII
                        10  20      60      80

                            PROBABILITY
                                                             90
99
Probability distribution of concentrations of acenaphthene in  sediments  from
streams, lakes and estuaries in the United States from 1986 to 1990 from the
STORET (U.S. EPA, 1989b) database, compared to the acenaphthene SQC values
of 13 pg/g in freshwater sediments having TOC  = 10% and  1.3 pg/g in
freshwater sediments having  TOC  =  1% and compared to SQC values for
saltwater sediments of 23 pg/g when TOC =10% and 2.3 pg/g when TOC=1 %.
The upper dashed line on each figure represents the SQC value when TOC =
10%, the lower dashed line represents the SQC when TOC  = 1%.
                          5-13

-------
generally at about 0.1 /ag/g in each of these three types of water bodies.   Acenaphthene




concentrations in sediments range over seven orders of magnitude throughout the country.



       The SQC for acenaphthene can be compared to existing concentrations of acenaphthene



in sediments of natural water systems in the United States as contained in the STORET database



(U.S. EPA, 1989b).  These data are generally reported on a dry weight basis,  rather than an



organic carbon normalized basis.  Therefore, SQC values corresponding to sediment organic



carbon levels of 1 to 10 percent are compared to acenaphthene's distribution in sediments as




examples only. For fresh water sediments, SQC values are 1.3 /*g/g in sediments having 1 %



organic carbon and 13 /ag/g dry weight in sediments having 10% organic carbon; for marine




sediments SQC are 2.3 /tg/g and 23 j*g/g, respectively.  Figure 5-3 presents the comparisons



of these SQC to probability distributions of observed sediment acenaphthene levels for streams



and lakes (fresh water systems, shown on the upper panels) and estuaries (marine systems, lower



panel).   For streams (n = 681)  the SQC of 1.3 /*g/g for 1 % organic carbon fresh water



sediments is exceeded by less than 4 % of the data;  the 13 /tg/g criteria for 10% organic carbon




freshwater sediments is exceeded in about 2 % of the samples.  For lakes (n = 56), the SQC for



1 % organic carbon fresh water sediments is exceeded by about 2% of the samples, while the



SQC for 10  % organic carbon fresh water sediments is not exceeded by any of the lake samples.



In estuaries, the data (n = 74) indicate that neither of the criteria of 2.3 /ig/g dry weight for salt



water sediments having  1 % organic carbon or 23 jig/g dry  weight for salt water  sediments




having 10 % organic carbon are exceeded,  although the STORET database for marine sediments




is not as extensive as the database for freshwater sediments.



       The acenaphthene distribution in Figure 5-3 includes data from  some samples in which
                                         5-14

-------
the acenaphthene concentration was below the detection limit.  These data are indicated on the
                                                                          •*
plot as "less than" symbols (<), and plotted at the reported detection limits.  Because these

values represent upper bounds and not measured values the percentage of samples in which the

SQC values are actually exceeded may be less than the percentage reported.

        A second database developed as part of the National Status and Trends Program

(NOAA, 1991) is also available for assessing contaminant levels in marine sediments that are

representative of areas away from sources of contamination.  The probability distribution for

these  data, which can be directly expressed on an organic  carbon basis,  is compared to the

saltwater SQC for acenaphthene (230 /tg/goc) on Figure 5-4. Data presented are from sediments

with 0.20 to 31.9% organic carbon.   None of these samples (n=288) exceeded the criteria.

Hence,  these results are consistent with the preceding comparison of the marine  SQC to

STORET data.

      Regional differences in acenaphthene concentrations  may affect the above conclusions

concerning expected criteria exceedences.  This analysis also does not consider other factors

such as the type of samples collected (i.e., whether samples were from surficial grab samples

or vertical core profiles), or the relative frequencies and intensities of sampling in different study

areas.  It is presented as an aid in  assessing the range of reported acenaphthene sediment

concentrations and the extent to which they may exceed the  sediment quality criteria.




5.5 LIMITATIONS TO THE APPLICABILITY OF SEDIMENT QUALITY CRITERIA:

      Rarely,  if ever,  are  contaminants found alone in naturally occurring' sediments.

Obviously, the fact that the concentration of a particular contaminant does not exceed the SQC
                                         5-15

-------
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                           5-16

-------
 does not mean that other chemicals, for which there are no SQC available, are not present in
                                                                           *
 concentrations sufficient to cause harmful effects. Furthermore, even if SQC were available for

 all of the contaminants in a particular sediment, there might be additive or synergistic effects

 that the criteria do not address.  In this sense the SQC represent "best case"  criteria.

       The concerns about mixtures of contaminants are particularly important with the PAHs,

 which almost invariably occur as complex mixtures.  Some guidance on interpretations of PAH

 concentrations is possible given the presence of SQC for acenaphthene and other individual

 PAHs.  This is because much is known about the toxicity and structure-activity relationships of

 the so-called narcosis chemicals, a group  of nonionic organic chemicals to which the PAHs

 belong.  The  toxicity of the narcosis chemicals is additive (Broderius and Kahl, 1985).  The

 toxicity of these chemicals increases with increasing KQW (Veith et  al.,  1983) and their

 bioavailability in sediments decreases as a function of its KQW. Therefore, the toxicities of many

 PAHs in sediments are likely to be similar.  This explains why SQC values for fluoranthene

 (fresh: 620 Atg/goc, salt: 300 /*g/goc)> acenaphthene (fresh:  130 ^tg/goc,  salt: 230 Mg/goc^ and

phenanthrene  (fresh: 180  /ig/goc, salt: 240 jtg/goc) differ little and why it is theoretically

possible to develop an SQC for total PAHs.  EPA is currently conducting research aimed at

development of SQC for combined PAHs.

      It is theoretically possible that antagonistic reactions between chemicals could reduce the

toxicity of a given chemical such that  it  might not  cause unacceptable effects on  benthic

organisms at concentrations above the SQC when it occurs with the antagonistic chemical.

However, antagonisms have rarely been demonstrated. What should be much more common are

instances where toxic effects occur at concentrations below the SQC because of the additivity
                                         5-17

-------
of toxicity of many common contaminants (Alabaster and Lloyd, 1982), e.g. heavy metals and
                                                                         «

PAHs, and instances where other toxic compounds for which no SQC exist occur along with

SQC chemicals.


       Care must be used in application of EqP-based SQC in disequilibrium conditions.  In


some instances site-specific SQC may be required to address this condition. EqP-based SQC


assume that nonionic organic chemicals are in equilibrium with the sediment and IW and are


associated with sediment primarily through adsorption into sediment organic carbon. In order


for these assumptions to be valid, the chemical must be dissolved in IW and partitioned into


sediment organic carbon.  The chemical must, therefore, be associated with the sediment for a


sufficient length of time for equilibrium to be reached. In sediments where particles like cinder,


soot, or oil droplets contain  PAHs, disequilibrium exists and criteria are over protective.  In


liquid chemical spill situations disequilibrium concentrations in interstitial and overlying water


may be proportionately higher relative to sediment concentrations.  In this case criteria may be


underprotective.


      In very dynamic areas,  with highly erosional or depositional  bedded sediments,


equilibrium may not be attained with contaminants.  However, even high KQW nonionic organic


compounds come to equilibrium in clean sediment in a period  of  days,  weeks or months.


Equilibrium times are shorter for mixtures of two sediments each previously at equilibrium.


This is particularly relevant in tidal situations where large volumes of sediments are eroded and


deposited, yet near equilibrium conditions may predominate over large areas. Except for spills


and paniculate chemical, near equilibrium is the rule  and disequilibrium is uncommon.   In


instances where it is suspected that EqP does not apply for a particular sediment because of
                                        5-18

-------
disequilibrium discussed above, site-specific methodologies may be applied (U.S. EPA, 1993b).
                                        5-19

-------

-------
                                      SECTION 6



                               CRITERIA STATEMENT








       The procedures described in the "Technical Basis for Deriving Sediment Quality Criteria




for Nonionic Organic Contaminants by Using Equilibrium Partitioning" (U.S. EPA, 1993a)




indicate that benthic organisms should be acceptably protected in freshwater sediments containing




_<. 130 fig  acenaphthene/g organic carbon and saltwater sediments containing _<. 230  fig




acenaphthene/g organic carbon, except possibly where  a locally important species is very



sensitive or sediment organic carbon is  < 0.2%.




       Confidence limits of 62 to 280 /ttg/goC for freshwater sediments and 110 to 500 A*g/goc




for saltwater sediments are provided as an estimate of the uncertainty associated with the degree




to which the observed concentration in sediment 0*g/goc)> which may be toxic, can be predicted



using the organic carbon partition coefficient (KoC) and the water-only effects concentration.



Confidence limits do not incorporate uncertainty associated with water quality  criteria.  An



understanding of the theoretical basis of the equilibrium partitioning methodology, uncertainty,



the partitioning and toxicity of acenaphthene, and sound judgement are required in the regulatory



use of SQC and their confidence limits.




      These concentrations represent the U.S. EPA's best judgement at this time of the levels



of acenaphthene in sediments that would be protective of benthic species.   It is the philosophy



of the Agency and the EPA Science Advisory Board that the use of sediment quality criteria



(SQCs)  as stand-alone, pass-fail criteria is not recommended  for all applications and should
                                          6-1

-------
frequently trigger additional studies at sites under investigation. The upper confidence limit
                                                                            'i
should be interpreted as a concentration above which impacts on benthic species should be

expected. Conversely, the lower confidence limit should be interpreted as a concentration below

which impacts on benthic species should be unlikely.
                                           6-2

-------
                                     SECTION 7
                                    REFERENCES

 Academy of Natural Sciences, 1981.  Early life stage studies using the fathead minnow
       (Pimephales promelas^ to assess the effects of isophorone and acenaphthene. Final report
       to U.S. EPA, Cinn., OH. Academy of Natural Sciences, Philadelphia, PA. 26 pp.

 Adams, W.J., R.A. Kimerle and R.C. Mosher. 1985. Aquatic safety assessment of chemicals
       sorbed to sediments.   In:  Aquatic Toxicology and Hazard  Assessment:   Seventh
       Symposium. Eds: R.D. Cardwell, R. Purdy and R.C. Banner. Amer. Soc. Testing and
       Materials, Philadelphia, PA. STP 854. pp. 429-453.

 Alabaster, J.S. and R. Lloyd. 1982. Water Quality Criteria for freshwater fish.  Chapter 11.
       Mixtures  of Toxicants.  London, Butterworth Scientific.

 Arbuckle, W.B.  1983.  Estimating activity coefficients for use in calculating environmental
       parameters.   Environ. Sci. Technol.  17(9):537-542.

 Banerjee, S.; S.H. Yalkowsky, and S.C. Valvani, 1980.  Water solubility and octanol/water
       partition  coefficients of organics:   Limitations  of the solubility-partition coefficient
       correlation.   Environ. Sci. Technol.  14(10): 1227-1229.

Broderius, S. and M. Kahl. 1985. Acute toxicity of organic chemical mixtures to the fathead
       minnow.  Aquatic Toxicol. 6:307-322.

Brookes, P.  1977.  Mutagenicity of polycyclic aromatic hydrocarbons.  Mutation Res. 39:257-
       284.

Buccafusco,  R.J., S.J. Ells and G.A.  LeBlanc. 1981. Acute toxicity of priority pollutants to
       bluegill (Leopomis macrochirust. Bull. Environ. Contam. Toxicol. 26:446-452.

Cairns, M. A. and A. V. Nebeker. 1982. Toxicity  of acenaphthene and isophorone to early life
       stages of fathead minnows. Arch. Environ. Contam. Toxicol. 11:703-707.

Callahan, M.A.,  M.W. Slimak, N.W.  Gabel, I.P. May, C.F. Fowler, J.R. Freed, P. Jennings,
       R.L.  Durfee, F.C.  Wbitmore, B. Maestri, W.R. Mabey, B.R. Holt, and C. Gould.

                                        7-1

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       1979.   Water-related environmental fate of  129 priority  pollutants.  Volume H:
       Halogenated aliphatic hydrocarbons, halogenated ethers, monocyclic aromatics, phthalate
       esters, polycyclic aromatic hydrocarbons, nitrosamines, and miscellaneous compounds.
       U.S.  EPA, Office of Water Planning  and  Standards, Office of  Water and Waste
       Management, Washington, DC, EPA-440/4-79-029b.

 Chapman, G. A. 1987.  Establishing sediment criteria for chemicals-regulatory perspective. In:
       Fate and Effects of Sediment-Bound Chemicals in Aquatic  Systems.  Editors: K.L.
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                                        7-2

-------
Hoke, R. 1992. Results of the third dieldrin sediment-spiking experiment.  Memorandum to D.
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Mabey, W.R., J.H. Smith, R.T. Podoll, H.L. Johnson, T. Mill, T.W., Chou, J. Gates, I.W.
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                                        7-3

-------
       DC, Final Report, EPA-440/4-81-041.
                                                                       •*•
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                                        7-4

-------
       oxidation. J. Water Pollut. Control Fed. 52:2117-2130.
                                                                        «
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                                        7-5

-------
U.S. Environmental Protection Agency. 1985. Appendix B - Response to public comments on
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                                        7-6

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Yalkowsky, S.H., and S.C. Valvani.  1979.  Solubilities and partitioning 2:  Relationships
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                                        7-7

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