protocol for the derivation of canadian sediment quality guidelines

Protocol for the Derivation of Canadian Sediment QualityGuidelines for the Protection of Aquatic Life

Canadian Council of Ministers of the Environment 1995CCME EPC-98E

Contents

Abstract ................................................................................................1Rsum.................................................................................................2Acknowledgments ................................................................................2Preface..................................................................................................2Glossary................................................................................................4

1. The derivation of Canadian sediment quality guidelinesfor the protection of aquatic life ......................................................5

Introduction.....................................................................................5Canadian perspective ......................................................................5Guiding principles...........................................................................6Overview of guideline development................................................7

Literature search and evaluation ..................................................7Background concentrations of natural substances .......................7Derivation of guidelines...............................................................9

Guideline derivation procedures......................................................9The National Status and Trends Program approach...................10

Evaluation of toxicological data ...........................................10Minimum data set requirements ...........................................11Derivation of guidelines .......................................................12

The spiked-sediment toxicity test approach ..............................12Minimum data set requirements ...........................................12Derivation of guidelines .......................................................13

Interim sediment quality guidelines adopted from otherjurisdictions............................................................................... 13

Recommendation of Canadian sediment quality guidelines.......... 13The role of sediment quality guidelines ........................................ 14

2. The use of sediment quality guidelines as benchmarks................. 15

Introduction................................................................................... 15Application of sediment quality guidelines as benchmarks .......... 16A generic example ........................................................................ 16

Water and land use activities..................................................... 16Existing sediment chemistry data.............................................. 18Supplemental sediment chemistry data ..................................... 18The potential for adverse biological effects ............................... 19Background concentrations of natural substances..................... 19Biological assessment................................................................ 20Management options ................................................................. 22

Appendix A. The National Status and Trends Program approach ...... 22Appendix B. The spiked-sediment toxicity test approach .................. 28Appendix C. Derivation of safety factors ........................................... 29

References.......................................................................................... 32

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Canadian Sediment QualityGuidelines for the Protectionof Aquatic Life

PROTOCOLAbstract

Sediments provide habitat for many benthic and epibenthic organisms. They also influence the environmentalmany chemical substances in aquatic ecosystems by acting as both sinks and subsequently sources of substahave entered the aquatic environment. Many aquatic organisms may be exposed to chemical substances throuimmediate interactions with bed sediments; therefore, benchmarks of environmental quality (such as sedimentguidelines) are required to support protection and management strategies for freshwater, estuarine, and mecosystems. Under the auspices of the Canadian Council of Ministers of the Environment (CCME), Canadian sequality guidelines for the protection of aquatic life are being developed through the CCME Task Group on Water QGuidelines. These sediment quality guidelines can be used to assess sediment quality, to help set targets for quality that will sustain aquatic ecosystem health for the long term, and to develop site-specific objectives. This dooutlines the procedures that are set out for deriving scientifically sound national sediment quality guidelines fprotection of aquatic life. Introductory guidance is also provided on how these guidelines are intended to be uconjuction with other types of information.Canadian Environmental Quality GuidelinesCanadian Council of Ministers of the Environment, 1999

PROTOCOL Canadian Sediment Quality Guidelinesfor the Protection of Aquatic Life

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Les sdiments servent dhabitat de nombreux organismes benthiques et pibenthiques. Ils influent galement surenvironnemental de nombreuses substances chimiques dans les cosystmes aquatiques en se comportant lapuits daccumulation et par la suite comme sources des substances qui se sont introduites dans lenvironnement aNombre dorganismes aquatiques peuvent tre exposs des substances chimiques par suite de leurs interactions avec les sdiments du lit; par consquent, des points de repre en matire de qualit environnementale (corecommandations pour la qualit des sdiments) sont ncessaires pour appuyer les stratgies de protection et de gcosystmes deau douce et des cosystmes estuariens et marins. Des recommandations canadiennes pour lasdiments visant protger la vie aquatique sont en voie dlaboration par lintermdiaire du Groupe de travail recommandations pour la qualit des eaux, sous les auspices du Conseil canadien des ministres de lenvironnemenCes recommandations pour la qualit des sdiments peuvent servir valuer la qualit des sdiments, fixer des omatire de qualit des sdiments qui favorisent la sant long terme des cosystmes aquatiques et tablir depropres des sites spcifiques. Le prsent document dcrit les mthodes en place pour llaboration de recommnationales pour la qualit des sdiments qui reposent sur des fondements scientifiques solides et qui ont pour but dla vie aquatique. On fournit galement une introduction sur lutilisation prvue de ces recommandations en combavec dautres types de renseignements.anada,2E0).ranch,and M.

are alsoion andeanicection,Quality TaskAcknowledgments

Drafts of this document were prepared by S.L. Smith (Evaluation and Interpretation Branch, Environment COttawa, Ont. K1A OH3) and D.D. MacDonald (MacDonald Environmental Sciences Ltd., Ladysmith, B.C. VOR Individuals who contributed significantly to this report include Karen Keenleyside (Evaluation and Interpretation BEnvironment Canada); John Karau and Jim Osborne (Office of Waste Management, Environment Canada); Bewers and D.H. Loring (Bedford Institute of Oceanography, Department of Fisheries and Oceans). Thanks extended to Connie Gaudet, Amanda Brady, Larissa Thomas, Rob Kent, Don McGirr, and Michael Wong (EvaluatInterpretation Branch, Environment Canada); Dwight Williamson (Manitoba Environment); Ed Long (National Ocand Atmospheric Administration, Seattle, Wash.); Fred Calder (Florida Department of Environmental ProtTallahassee, Fla.); and the members of the Interdepartmental Working Group on Marine Environmental Guidelines, the members of the Marine Environmental Quality Advisory Group, and the members of the CCMEGroup on Water Quality Guidelines for their technical advice and reviews.a

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Canadian sediment guidelines for the protection of aqualife are being developed under the auspices of tCanadian Council of Ministers of the Environmen(CCME). Sediment quality issues have become important focus in the environmental assessmeprotection, and management of aquatic ecosystemHistorically, water quality activities were motivated byconcerns for human health (e.g., drinking water qualiguidelines) (Health and Welfare Canada 1993), battention has shifted in recent years towards the protectof other components of the ecosystem (e.g., sedimensoil) and other water uses. These water uses inclufreshwater and marine aquatic life, recreation anaesthetics, irrigation and livestock watering, and industrwater supplies. In Canada, acceptable water quality for 2

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protection of these uses has been evaluated against Canadian water quality guidelines (CCREM 1987)Sediment quality guidelines for the protection of aquatilife will be used in a complementary manner to evaluasediment quality.

The Canadian water quality guidelines were adopted othe basis of a review and evaluation of existing watequality guidelines from other jurisdictions (CCREM1987). In some cases, scientific information was used modify the guidelines so that they were applicable tCanadian conditions. Guidelines were not recommendfor the parameters for which guidelines from othejurisdictions were deemed inappropriate or for whichscientific data were lacking. Recently, a formal protoco

Canadian Sediment Quality Guidelinesfor the Protection of Aquatic Life

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itytedhas been developed for the consistent derivationnumerical water quality guidelines for the protection freshwater and marine aquatic life (CCME 1991a) and the protection of agricultural water uses (CCME 199Similarly, interim soil quality guidelines have beeadopted for 60 substances, and a formal protocol for trefinement is currently being developed (CCME 19911994; Environment Canada 1991).

Water quality guidelines play an important role protecting water uses and in assessing the impacenvironmental contaminants on the quality and usesaquatic resources. Sediment quality guidelines are important because sediments have a profound influencthe health of aquatic organisms, which may be exposechemicals through their immediate interactions with bsediments. Therefore, the use of sediment quaguidelines for evaluating the toxicological significance sediment-associated chemicals has become an impopart of the protection and management of freshwaestuarine, and marine ecosystems.

In 1989, the CCME Environmental Protection Committmandated the responsibility of establishing Canadsediment quality guidelines (SQGs) to the CCME TaGroup on Water Quality Guidelines. The Evaluation aInterpretation Branch, Ecosystem Conservation Directorof Environment Canada provides scientific and technisupport to the Task Group on the development of thguidelines. Sediment quality guidelines can be usedhelp set targets for sediment quality that will sustaaquatic ecosystem health for the long term. They required to support the interpretation of sediment chemidata and the overall assessment of sediment quconditions within the context of specific water uses, athey support the development of site-specific objectives.

The use and interpretation of the terms criteria,guidelines, objectives, and standards vary among differentagencies and countries. For the purposes of this documthese terms are defined as follows:

Criteria - The scientific data that are evaluated to dersediment quality guidelines.

Guidelines - Numerical limits or narrative statementrecommended to support and maintain designated uof the aquatic environment.

Objectives - Numerical limits or narrative statements thhave been established to protect and maintain designuses of the aquatic environment at a particular site.3

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Standards - Sediment quality objectives that arerecognized in enforceable environmental control lawof one or more levels of government.

These definitions are consistent with those used in tdiscussion of Canadian water quality guidelines (CCRE1987). The term sediment refers to the bottom deposits inaquatic environments that are composed of particulamaterial (of various sizes, shapes, mineralogy) frovarious sources (e.g., terrigenous, biogenic, authigenic).

In response to the identified need for SQGs in CanadEnvironment Canada commissioned a study in 198(MacDonald et al. 1992) to review and evaluate thavailable approaches used to develop such guidelines. document also provided an extensive compilation existing sediment quality assessment values from arouthe world. The approaches reviewed included those of th

sediment background spiked-sediment toxicity test water quality guidelines interstitial water toxicity equilibrium partitioning tissue residue benthic community structure assessment screening level concentration sediment quality triad apparent effect threshold International Joint Commission sediment assessment

strategy National Status and Trends Program

MacDonald et al. (1992) provided a brief description othe methodology of each of the approaches, their maadvantages and limitations, and their current useNumerous other reviews of these approaches have bpublished (Beak Consultants 1987, 1988; Chapman 19Sediment Criteria Subcommittee 1989; Adams et al. 199Persaud et al. 1992; Lamberson and Swantz 1992: Loand MacDonald 1992).

A preliminary evaluation indicated at that time that nsingle approach was likely to fully support the immediatneed for national, scientifically defensible guidelines, awell as the long-term need for guidelines that explicitlconsider the factors that influence the toxicity osediment-associated contaminants. Until a formalizeprotocol was developed, MacDonald et al. (1992recommended that effect-based sediment qualassessment values from other jurisdictions be evaluafor their applicability to Canadian conditions, modified


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iongGslitywith existing scientific data (if necessary) to increase thapplicability to Canadian conditions, and adopted interim sediment quality guidelines if deemed suitabThis recommendation parallels the initial CCME stratefollowed for adopting interim water quality and soquality guidelines.

Further to the recommendations of MacDonald et (1992), a study was commissioned by EnvironmeCanada to validate and update the National Status Trends Program database (developed by the NatioOceanic and Atmospheric Administration), whiccontained information on the biological effects osediment-associated contaminants. The results of thinitiatives provided a sound basis for developing a formprotocol (presented in Chapter 1) for the developmentnational SQGs for use in Canada.

The formal protocol established for the derivation numerical SQGs is applicable to the protection of bofreshwater and marine (including estuarine) aquatic lassociated with bed sediments (separate guidelines derived for each of these systems). The protocol remainly on the National Status and Trends Prograapproach, with the complementary use of the spikesediment toxicity test approach in the future, onmethodological concerns have been resolved. Becausedevelopment of SQGs relies on current scientifinformation, they will be refined as new and relevant dabecome available.

Sediment quality guidelines are developed from tavailable scientific information on the biological effec4

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of sediment-associated chemicals. These tools intended to provide guidance to provincial, federaterritorial, and nongovernmental agencies involved in tprotection, assessment, and management of sedimquality. SQGs provide a scientific review the existintoxicological information for a chemical, which can bused to support the establishment of sediment quaobjectives to protect aquatic life, which are developedreflect a number of site-specific considerations. Trecommended SQGs may be employed as nationconsistent screening tools; however, variations environmental conditions across Canada will affesediment quality in different ways. Complementainformation on background concentrations of natusubstances is evaluated during the development of SQand should be considered during their implementation athe development of site-specific sediment qualobjectives. Impairment of sediments of superior qualitynational guideline concentrations should not be advoca

This document focuses on the procedures to be usederiving national SQGs for the protection of aquatic lifNational SQGs are currently being developed onchemical-by-chemical basis through the CCME TaGroup on Water Quality Guidelines. This document alprovides introductory guidance on how these guidelinare intended to be used with other types of informatand will be followed by other documents providinnational guidance specific to the implementation of SQand the development of site-specific sediment quaobjectives.Glossary

ASTM American Society for Testing and MaterialsBEDS Biological Effects Database for SedimentsCCREM Canadian Council of Resource and

Environment MinistersCCME Canadian Council of Ministers of the

EnvironmentEC50 median effective concentrationERL effects range lowERM effects range medianISQG interim sediment quality guidelineLC50 median lethal concentrationLOEL lowest-observed-effect level

NC no concordanceNE no effectNG no gradientNOEL no-observed-effect levelNSTP National Status and Trends ProgramPEL probable effect levelSG small gradientSQG sediment quality guidelineSSTT spiked-sediment toxicity testTEL threshold effect levelTOC total organic carbon


PROTOCOL

Chapter 1The Derivation of Canadian Sediment Quality Guidelines

for the Protection of Aquatic Life

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erINTRODUCTION

Sediments provide habitat for many benthic and epibentorganisms and are an important component of aquecosystems. Sediments also influence the environmentalof many toxic and bioaccumulative substances in aquaecosystems. Many substances form associations wparticulate matter and are eventually incorporated into bsediments (Allan 1986). Consequently, sediments may aact as long-term sources of these substances to the aqenvironment (Larsson 1985; Salomons et al. 1987; Lorand Rantala 1992).

Chemical contaminants in sediments have been associwith a wide range of impacts on the plants and animthat live within and upon bed sediments. Both acute achronic toxicity of sediment-associated chemicals algae, invertebrates, fish, and other organisms have bmeasured in laboratory toxicity tests (Thomas et al. 19Kosalwat and Knight 1987; Dawson et al. 1988; Long aMorgan 1990; Burton 1991, 1992; Burton et al. 199Lamberson et al. 1992). Field surveys have identified subtler effects of environmental contaminants, such as development of tumours and other abnormalities bottom-feeding fish (Malins et al. 1984; Couch anHarshbarger 1985; Malins et al. 1985; Goyette et 1988). Sediment-associated chemicals also have potential to accumulate in the tissues of aquatic organis(Foster et al. 1987; Knezovich et al. 1987). Elevattissue concentrations in benthic or other aquatic organiscan result in the bioaccumulation of chemicals in highlevels of the aquatic food web (Government of Cana1991a, 1991c). (Bioaccumulation in the context of thdocument is defined as the process by which substanare accumulated by aquatic organisms from all routesexposure.) The bioaccumulation of chemicals in aquaorganisms presents a potential hazard to sensitive wildspecies, birds, and humans that rely on these organifor food.

The continual release of chemicals into the environmeas a consequence of human activities has resultedvarying degrees of contamination of aquatic ecosysteacross Canada (Waldichuk 1988; Goyette and Boyd 1989Allan and Ball 1990; Government of Canada 19911991b, 1991c; Trudel 1991; Wells and Rolston 19915

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Because sediments tend to integrate contaminant inpover time, they represent potentially significant hazardsthe health of aquatic organisms and to the overall healthaquatic ecosystems. Therefore, sediment qualguidelines (SQGs) for the protection of aquatic life arequired to assess the toxicological significance sediment-associated chemicals in freshwater, estuarand marine ecosystems.aticg

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CANADIAN PERSPECTIVE

Ideally, SQGs should be developed from detailed dosresponse data that describe the acute and chronic toxof individual chemicals in sediments to sensitive lifstages of sensitive species of aquatic organisms. Thdata should be generated in controlled laboratory studin which the influence of important environmentavariables that affect toxicity are identified and quantifieThe results of these studies should then be validatedfield trials to ensure that any SQGs derived from thedata are applicable in a broad range of locations Canada. A detailed understanding of the factors thinfluence toxicity would also support site-specifisediment quality assessments by providing a basis evaluating the applicability of guidelines under sitespecific conditions (e.g., total organic carbon [TOCgrain size, acid volatile sulphide) (DeWitt et al. 1988; DToro et al. 1990; Landrum and Robbins 1990; Swartzal. 1990; Carlson et al. 1991; Di Toro et al. 1991; Lorinand Rantala 1992; Ankley et al. 1991, 1993). Therelationships need to be defined to the extent that relative importance of the modifiers of sediment toxicitare predictable under field situations.

Currently, this ideal approach is not supported badequate scientific information to facilitate the develoment of national SQGs. To date, only a limited number controlled laboratory studies have been conducted assess the effects of sediment-associated chemicalsestuarine, marine, and freshwater organisms (Loand Morgan 1990; Burton 1991; MacDonald 1993Additional research into sediment-spiking methodologiis also required before the results of spiked-sedimbioassays can be used to generate doseresponse appropriate for guideline development. However, oth


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ealltypes of data that are routinely collected throughout NoAmerica contribute to our understanding of the toxeffects of these chemicals. Specifically, a wide variety sediment toxicity tests have been conducted to assessbiological significance of concentrations of chemicals sediments from specific geographic locations. Thetoxicity tests include those performed on benthorganisms (e.g., bivalve mollusks, shrimp, amphipodpolychaetes, nematodes, chironomids) and on pelaorganisms (e.g., sea urchin larvae, oyster larvluminescent bacteria). Further, numerous field studhave been conducted that assess the diversity abundance of benthic infaunal and epifaunal specComprehensive data on the concentrations of chemicalthese sediments have also been collected for manythese field studies (Long and Morgan 1990; MacDona1993). Specific characteristics of the sediments and overlying water column also aid in the interpretation the corresponding toxicity data for the studies for whithis information has been collected. These field studiwhich report matching sediment chemistry and biologiceffect data (i.e., data are collected from the same locatiat the same time), provide information relevant to tSQG derivation process.

Available approaches to the development of SQGs wevaluated to determine which procedures would be mapplicable in Canada to the development of nationSQGs for the protection of aquatic life (MacDonald et a1992). In addition to the technical basis of theapproaches, their practicality, scientific defensibility, anapplicability were evaluated. The results of thecomprehensive evaluations of the major approaches lethe establishment of a formal protocol that builds on tstrengths of two complementary approaches: the NatioStatus and Trends Program (NSTP) approach (Appendix A) and the spiked-sediment toxicity test (SSTapproach (see Appendix B).

The formal protocol described in the following sections considered to be appropriate because it fulfils both immediate and long-term needs for national SQGs Canada. The protocol is practical in that it can implemented in the short term using existing data. Itscientifically defensible because it is supported byweight of evidence of the available toxicological data osediment-associated chemicals. For SQGs to be effecin Canada, they must be formulated from an undstanding of biological effects (preferably cause-and-efferelationships, including data on sensitive end points ligrowth, reproduction, and genotoxicity), and they shouaccount for the factors (e.g., TOC) that influence tbioavailability of sediment-associated chemicals. Sinthicof theinseics,gice,

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information on the toxicity of field-collected sediments iused in deriving guidelines, the various factors that affethe bioavailability of chemicals are implicitly consideredas well as the effects of mixtures of chemicals. Therefothe guidelines derived using this protocol are applicablesediments under field conditions. The guideline derivatiprocedure is also applicable to all classes of chemical amixtures of chemicals that are likely to occur in Canadiasediments. This procedure provides long-terapplicability in that it provides a focus for researcactivities that will support guideline development, and allows for the refinement of SQGs as new scientifinformation becomes available. Therefore, the SQGdeveloped will provide relevant benchmarks foaddressing the protection of benthic organisms and assessing the potential impact of sediment-associachemicals on aquatic biota.

Sediment quality guidelines formulated on the basis biological-effect data of sediment-associated chemicare intended to be used as nationally consistebenchmarks. During their implementation, howeveallowance must be made for the incidence of natuinorganic and organic substances in sediments. Advebiological effects may be observed below measurchemical concentrations that are attributable to natuenrichment. However, management concerns over potential for adverse effects of sediment-associatchemicals (particularly trace metals) must be practicafocused on those chemicals whose concentrations hbeen augmented above those that would be expectedoccur naturally. Therefore, the potential for adversbiological effects as indicated by the exceedances SQGs must be evaluated in conjunction with othinformation such as the natural background concentratioof substances (see Chapter 2). In some managemscenarios, it may also be necessary to considconcentrations of ubiquitous organic chemicals (i.e., tlow level contamination of certain substances that afound throughout many environmental compartments) thare representative of reference or clean sites.6

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GUIDING PRINCIPLES

The following guiding principles for the development oCanadian SQGs for the protection of aquatic life are bason those adopted by the Canadian Council of Ministersthe Environment (CCME 1991a) for the development oCanadian water quality guidelines.

SQGs are numerical concentrations or narrativstatements that are set with the intention to protect


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forms of aquatic life and all aspects of their aquatic lcycles during an indefinite period of exposure substances associated with bed sediments.

In deriving SQGs for the protection of aquatic life, a

components of the aquatic ecosystem (e.g., bacteria, amacrophytes, invertebrates, fish) are considered, if the are available. However, evaluation of the available dshould focus on ecologically relevant species.

Interim SQGs (ISQGs) are derived when data are availa

but limited, and information gaps are explicitly outlined. Unless otherwise specified, SQGs refer to the to

concentration of the substance in surficial sediments (the upper few centimetres) on a dry weight basis (emgkg-1 dry weight). However, sediments representcomplex and dynamic matrix of biotic and abiotcomponents that may influence the bioavailability sediment-associated chemicals. When sufficient infmation is available to define the influence of any facon the toxicity of a specific substance (e.g., TOC fnonpolar organic substances) (Swartz et al. 19Di Toro et al. 1991), the guidelines will be developed reflect this relationship. Consideration of thesrelationships will increase the applicability of guidelineto a wide variety of sediments throughout Canada.

SQGs are refined as new and relevant scientific dbecome available. The refinement of these guidelinesthe longer term will provide a means of ensuring thbroader applicability.nic

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veingOVERVIEW OF GUIDELINE DEVELOPMENT

The process for developing Canadian SQGs follows tgeneral framework that has been established for tderivation of water quality guidelines (CCME 1991a)This process involves a comprehensive evaluation of tavailable scientific information on a particular substancto support the development of national SQGs (Figure 1This section gives a brief overview of this process, witdetails of the guideline derivation procedures describedthe next section.

Literature Search and Evaluation

A comprehensive review of the scientific literature iperformed for each substance for which guidelineare to be derived. Introductory information is briefly7

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summarized on the substances physical and chemiproperties, its production and uses, and its sources to aquatic environment. More detailed discussions aincluded with respect to concentrations of the chemicfound in Canadian sediments (including naturabackground concentrations), the chemistry and fate of tchemical in sediments, and the available toxicologicdata for the sediment-associated chemical. Eatoxicological study retrieved from the scientific literatureis evaluated for its overall acceptability to ensure that higquality data are used in developing SQGs. Characteristof the sediment and the overlying water column areviewed if these factors have been measured, since information is used to help interpret the correspondintoxicological data. Finally, a review of existing guidelinefrom other jurisdictions is provided. Data gaps arexplicitly outlined to stimulate research that will generatthe necessary data to support guideline development.

Background Concentrations of NaturalSubstances

Regional background concentrations of natural inorganand organic substances occurring in sediments are aestablished, if possible, for freshwater and marinsystems. This information should be considered during timplementation of SQGs since, in some cases, natioguidelines (which are toxicologically based) may be lowethan the respective concentrations of naturally occurrinsubstances at a particular site (see Chapter 2 for genguidance on the use of SQGs with information obackground concentrations). This information is also aimportant component in the development of site-specifsediment quality objectives.

An interpretive tool has been developed that provides effective means of distinguishing the probable origin (i.enatural vs. anthropogenic) of many metals in marinsediments (Schropp and Windom 1988; Schropp et 1989; Loring 1990, 1991; Schropp et al. 1990; Loring anRantala 1992; MacDonald 1993). This method involvedetermining the ratio of measured trace element conctrations to that of a reference element at a number uncontaminated sites (such ratios are relatively constantthe earths crust). Although normalizations to a referenelement can be accomplished using a number of naturaoccurring elements (e.g., aluminum, iron, lithium), lithiumappears to be the most appropriate for redox positisediments in marine systems in eastern Canada (Lor1990, 1991).


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Data Requirements forSediment Type/Characteristics

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Recommend CanadianSQC or ISQG

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No Minimum Toxicological DataRequirements Met?

Guideline Derivation Tablefor No Biological Effects

Guideline Derivation Tablefor Biological Effects

National Status & Trends Program Approach

Evaluation Toxicological Datafor Acceptability

Review EnvironmentalChemistry and Fate Data

Evaluate/EstablishBackground Concentrations

Conduct Literature Search

Figure 1. Derivation of Canadian sediment quality guidelines.


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leetPTTinl.Data from a number of uncontaminated sites are useddevelop correlations between log transformed concenttions of various trace elements and those of the refereelement. Relationships between trace elements and lithare typically of the form y = ax + b (i.e., linear) (Loringand Rantala 1992). The constant b is significant when themeasured concentration of the trace element is highcoarse materials that are virtually devoid of lithium (e.gsand). A simple linear regression is performed on the dand the 95% confidence limits are calculated. Therelationships vary among locations (i.e., both the slopeaand the constant b may vary); however, they provide amethod for defining reasonable upper limits to the natuoccurrence of trace elements in marine sediments various sites (i.e., anthropogenic enrichment of traelements is suspected when the trace element to refereelement ratio at a site exceeds the upper 95% confidelimits) (Schropp and Windom 1988; Schropp et al. 198Loring 1990, 1991; Schropp et al. 1990; Loring anRantala 1992; MacDonald 1993).

A factor is added to account for the presence of traelements associated with the organic fraction of tsediments when organic carbon concentrations exceed(Loring and Rantala 1992). The normalized trace elemeconcentration in sediments is then defined as Cs = a + xCLi+ (|y| + y)/2, where y = (CTOC) - 0.03.

This method has been demonstrated only for some masediments (Schropp and Windom 1988; Schropp et 1989; Loring 1990, 1991; Schropp et al. 1990; Loring anRantala 1992; MacDonald 1993). Its applicability fodistinguishing the probable origin (i.e., natural vsanthropogenic) of trace elements in freshwater sedimeis unknown and should be investigated. Alternativmethods for evaluating the origin of some chemicals freshwater sediments may include the choice of appropriate reference area that is unaffected by poisource discharges, or the use of the pre-coloniasediment horizon (Persaud et al. 1992). Since syntheorganic chemicals are released into the environment oas a result of human activities, equivalent tools fdistinguishing their probable origin (i.e., natural vsanthropogenic) are needed for only the organic substanthat occur naturally (such as polycyclic aromatic hydrcarbons). Concentrations of naturally occurring organsubstances from essentially uncontaminated sedimentreference sites far from point-source discharges contaminants could be used as a guide to definisurrogate background concentrations of these substanc

Although the theoretical background concentrations synthetic organic chemicals released into the environm9

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as a result of human activities are zero, ubiquito(or low-level) contamination of the environment haoccurred. The concentrations of such organic containants could be established from reference sites chosefrom point sources of contaminants. Such referenconcentrations could be used as a guide to the expelevels of ubiquitous contamination at other sites.

Derivation of Guidelines

Guidelines are derived separately for freshwater amarine sediments using toxicological data compiled each of these systems. If the minimum data set requments are met for the NSTP approach, ISQGs are derusing the weight of evidence of available toxicologicinformation. Full SQGs are developed when the ISQcan be linked to specific sediment types and/or charteristics of either the sediments or of the overlying wacolumn (i.e., if a relationship is demonstrated to exist ais predictable under field conditions). SQGs will also derived in the future using the SSTT approach, onmethodological concerns have been resolved. In the sterm, however, this approach will be used to support weight of evidence of the NSTP approach. Guidelinderived using the above approaches do not specificaddress the potential for adverse effects on higher troplevels of the food chain resulting from the bioaccumution of persistent toxic substances. However, these isswill be addressed through the use of additional meth(e.g., involving the evaluation of bioaccumulation factoand tissue residue guidelines for the protection of wildlconsumers of aquatic life) before a full sediment quaguideline is recommended. In cases where thereinsufficient information to support the derivation of SQGor ISQGs using this formal protocol, the default proceof MacDonald et al. (1992) is recommended to adosuitable sediment quality assessment values from ojurisdictions for use in the interim.lyr

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GUIDELINE DERIVATION PROCEDURES

Specific procedures are described in this section deriving Canadian SQGs for the protection of aquatic lifThese steps include evaluating the quality of availabtoxicological data and the quantity of acceptabtoxicological data (as per the minimum data srequirements), and deriving guidelines using the NSTapproach. Procedures are also described for the SSapproach, which will support the development of SQGs the future. The recommendations of MacDonald et a(1992) are also summarized.


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The National Status and Trends ProgramApproach

The National Status and Trends Program approach invothe compilation of data for many chemicals that agenerated from models (equilibrium partitioning theorySSTTs, and field studies (co-occurrence data consistingmatching sediment chemistry and biological-effect da(Long and Morgan 1990; Long 1992; MacDonald 199Long et al. 1994). This information is used to establiassociations between concentrations of chemicals sediments and adverse biological effects, and thus strosupports the development of national SQGs based oweight-of-evidence approach. For a more detaildescription of the NSTP approach and supporting rationfor the procedures described below, see Appendix A.

Briefly, acceptable toxicological data that are incorporatinto guideline derivation tables (as illustrated Appendix A) are compiled on a chemical-by-chemical baand are sorted according to ascending chemiconcentrations. (These tables are referred to collectivelythe Biological Effects Database for Sediments, or BEDSeparate tables are compiled for freshwater and masediment toxicity information. Each entry (row) consists the measured chemical concentration, location, analytype (or approach), test duration, end point measurspecies and life-stage tested, whether associated biologeffects or no biological effects were observed, and the streference. Entries identified by an asterisk (*) in thEffect/No Effect column comprise the effect data se(i.e., observed biological effects were associated with measured chemical concentration). Entries for which effects were observed comprise the no-effect data set are indicated as NE (no effect [i.e., nontoxic, reference,control]), NG (no gradient), SG (small gradient), or NC (nconcordance). Data on characteristics of the sediment overlying water column are also summarized, wheavailable. Data are expressed as the total concentrationthe chemical in sediments on a dry weight basis.

The guideline derivation tables compiled for each chemiprovide the basis for deriving ISQGs using this weight-oevidence approach. The data evaluation criteria, minimtoxicological data requirements, and the procedures deriving guidelines using the information compiled BEDS are described below.

Evaluation of Toxicological Data

Accurate and precise data on sediment chemistry essential to understanding the relevance of toxicologi1

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test results. Standard sampling methods are also importto ensure that sediment collection, transport, and handliprocedures do not affect the results of chemical anbiological tests (ASTM 1990a; Loring and Rantala 1992Environment Canada 1994a). Since the bioavailability sediment chemicals is linked to the physical and chemicbonding of each chemical with particles in the samplcorresponding analyses of factors (e.g., TOC, particsize) that influence the bioavailability of sedimentassociated chemicals are important in order to comphensively explain observed adverse effects.

In general, toxicological data must be generated usiappropriate test methods. For example, methods shoinclude regular cycles of exposure to light and dark teconditions, and verification throughout the test on thcondition of the test species. In addition, the analyticchemistry of the test sediment and overlying water shoube determined at the beginning and end of the test. Teshould report data on the health of the test species priortesting. Information on the survival of the test species for least a week before the test should be available, and species should not be used where significant mortalitihave occurred during this time. Current sediment toxicitests under development are briefly reviewed in Chapter 2

With respect to the NSTP approach, candidate toxicoogical data sets are initially screened for acceptability ensure that high quality data are incorporated into BEDand that the guideline derivation tables are internalconsistent. The majority of studies that have beescreened into BEDS consist of field studies (i.e., cooccurrence data where sediment chemistry and biologiceffect data have been measured for the same locationthe same time). Studies are designated as acceptableinclusion in BEDS if the criteria below are met. (SeAppendix A for further details.)

The procedures used for the collection, handling, anstorage of saltwater and freshwater sediments shouldconsistent with standardized protocols (e.g., ASTM1990a; Loring and Rantala 1992; Environment Canad1994a). For example, sediments that have been stofor more than two weeks or frozen should not be usein biological tests.

Data used in co-occurrence analyses must contamatching sediment chemistry and biological-effect da(i.e., data must be collected from the same locationsthe same time).

The concentrations of one or more analyte(s) must vaby at least a factor of 10 at different sampling site0


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represented in a single co-occurrence data set (i.e., particular location).

Toxicity tests should employ generally accepte

laboratory practices of exposure and environmencontrols. Tests that follow standardized guides protocols (e.g., ASTM 1990b, 1990c; EnvironmenCanada 1992a, 1992b, 1992c) are acceptable. Tthat employ more novel protocols should be evaluaton a case-by-case basis.

Concentrations of the chemical in sediment must measured (with the number of measurements takdependent on the nature of the chemical and durationthe toxicity test). Calculated (nominal) concentrationof the substances in sediments are not acceptable.

Static, static-renewal, or flow-through aquatic tests m

be employed for assessing the toxicity of sedimenassociated chemicals. However, acceptable tests shodemonstrate that adequate environmental conditions the test species were maintained throughout the test.

Preferred end points include effects on embryondevelopment, early life-stage survival, growth, reprodution, and adult survival. However, other ecologicalrelevant end points may also be considered with respto the pathology, behaviour (e.g., avoidance, burrowinand physiology of the organism.

Responses and survival of controls must be measu

and within acceptable limits, and should be appropriafor the life stage of the species used in the test.

Appropriate analytical procedures must be used

generate data on the total concentrations of analytesbulk sediment samples. (Note that, for the purposesdetermining background concentrations of natursubstances at a site, hydrofluoric acid is used to digsamples before analysis for total metal concentratio[Schropp and Windom 1988; Loring and Rantala 1992]

Measurements of abiotic variables should be report

so that any factors that may affect toxicity can bincluded in the evaluation process. In the overlyinwater, variables should include pH, dissolved oxygetotal suspended solids, suspended and dissolvorganic carbon, and water hardness (and/or alkalinior salinity. In the sediment, reported variables shouinclude TOC, particle size distribution, acid volatilesulphide, pH, redox conditions, and sediment type.

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Appropriate statistical procedures should be used areported in detail.

Data are considered unacceptable for inclusion in BEDSinsufficient information was reported to assess thadequacy of the test design, procedures, and/or resultsany such deficiencies in information can be obtained clarified through the author(s), the study may eventuabe acceptable for inclusion in BEDS. (Note that full SQGcan be derived when the weight of evidence toxicological information is linked to specific sedimentypes and/or characteristics of either the sediment or of overlying water column, although this information [e.gTOC] is presently not required in order to include a studin BEDS.)

Minimum Data Set Requirements

The use of the NSTP approach for deriving ISQGs relion the compilation and analysis of all of the availabNorth American data, including data from many locationand on many species that are normally associated wsediments. Minimum toxicological data requirements habeen set to ensure that guidelines developed are suppoby the weight of evidence linking chemical concentrationto biological effects and that aquatic biota are adequatprotected. ISQGs for freshwater or marine sediments cbe derived from the studies compiled in BEDS providethat the minimum toxicological data set requiremenbelow are met.

Full SQGs can be derived from these ISQGs if supportiinformation is available to link the ISQGs with specificsediment types and/or characteristics of the sediment othe overlying water column (i.e., a weight of evidencmust clearly define the relationships of these factors wadverse biological effects).

Table 1. Minimum Toxicological Data Set Requirements forInterim Sediment Quality Guidelines (using theNSTP approach).

The effect data set for the chemical under consideration mcontain at least twenty (20) entries in the guideline derivatiotable prepared from BEDS.

The no-effect data set for the chemical under considerat

must contain at least twenty (20) entries in the guidelinderivation table prepared from BEDS.


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If the minimum data set requirements for the NSTapproach are met, the derivation of ISQGs can proceFor each chemical, a functional threshold effect level (TEis calculated as the square root of the product (i.e., geometric mean) of the lower 15th percenticoncentration of the effect data set (the E15) and the 50thpercentile concentration of the no-effect data set (tNE50). This TEL is calculated to consistently determinerange of sediment chemical concentrations that dominated by no-effect data entries (i.e., adverbiological effects are never or almost never observbelow the TEL). All relevant information on thebehaviour of the chemical in sediments and the availatoxicological information are evaluated in order trecommend the TEL as the ISQG. If the uncertainassociated with the TEL is high (as indicated after evaluation of the information in the guideline derivatiotables), a safety factor may be applied to the TEL (trationale for choosing a safety factor and the uncertainties may be considered are provided in Appendix C). Otherwithe TEL is considered representative of the concentratbelow which adverse effects are not anticipated.

To derive full SQGs, defensible relationships betwespecific sediment (e.g., TOC, particle size distributioand/or overlying water column characteristics (e.g., pand observed sediment toxicity must be supported byweight of evidence of the available informationCurrently, the available information indicates that onISQGs can be developed. However, some of these dgaps should be filled as information becomes availablesupport the SSTT approach.

The Spiked-Sediment Toxicity Test Approach

The spiked-sediment toxicity test (SSTT) approach iscomplementary procedure that will be used in the futureconfirm and strengthen guidelines developed using NSTP approach. The SSTT approach uses informationthe responses of test organisms to specific sedimeassociated chemicals under controlled laboratory contions (Chapman and Long 1983; Ingersoll 199Lamberson and Swartz 1992). Sediments are spiked wknown concentrations of chemicals, either alone or combination, to establish definitive cause-and-efferelationships between chemicals and biological responsAt the end of the test period, the response of the torganism is examined in relation to a biological end po(e.g., mortality, reproduction, growth). As in the1

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development of water quality guidelines in Canad(CCREM 1987) or water quality criteria in the UnitedStates (USEPA 1985, 1986), acute and chronic effect dagenerated from sediment toxicity tests can be used identify concentrations of chemicals in sediment belowwhich aquatic life would not be adversely affected. Fofurther background on this approach and supportinrationale for the procedures described below, seAppendix B. Recommendations for minimumtoxicological data requirements and procedures foderiving SQGs using the SSTT approach are describbelow. SQGs will be developed using this approach onmethodological concerns have been resolved.

Minimum Data Set Requirements

Minimum toxicological data requirements have been set ensure that guidelines developed using spiked-sedimetoxicity information provide adequate protection toaquatic organisms. Guidelines can be derived from studconducted on sensitive species that are not required in minimum data set (e.g., fish, aquatic plants, protozofungi, bacteria) provided that the following minimum dataset requirements are met.

Table 2. Minimum Data Set Requirements for Marine SedimentQuality Guidelines (using the SSTT approach).

At least four (4) studies are required on two (2) or morsediment-resident invertebrate species that occur in NorAmerican waters. At least one (1) of these must be a benthamphipod species.

At least two (2) of these studies must be partial or full lifecycle tests that consider ecologically relevant end poin(e.g., growth, reproduction, developmental effects).

Table 3. Minimum Data Set Requirements for FreshwaterSediment Quality Guidelines (using the SSTTapproach).

At least four (4) studies are required on two (2) or morsediment-resident invertebrate species that occur in NorAmerican waters. These must include at least one (1) benthcrustacean species and one (1) benthic arthropod species(other than a crustacean).

At least two (2) of these studies must be partial or full life-cycle tests that consider ecologically relevant end points(e.g., growth, reproduction, developmental effects).2


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If the minimum data set requirements are met for tSSTT approach, the derivation of SQGs can proceed. each chemical, SQGs are derived preferentially from lowest-observed-effect level (LOEL) from a chronic studusing a nonlethal end point. The most sensitive LOELmultiplied by an appropriate safety factor to derive thSQG. In situations where an acute study for anothspecies is most sensitive, the SQG is derived multiplying the most sensitive short-term median leth(LC50) or median effective (EC50) concentration by anappropriate safety factor (to convert it to a long-term neffect concentration). Rationale for the choice of thesafety factors (which are evaluated on a case-by-case band may consider a number of uncertainties) is providin Appendix C.

Species not required in the minimum data set may be uto calculate SQGs provided that the life stage undinvestigation is aquatic and the minimum data srequirements are satisfied. Each study selected for derivation of an SQG must have a demonstrated doresponse relationship and the LOEL must be statisticasignificant.

Interim Sediment Quality GuidelinesAdopted from Other Jurisdictions

Sediment quality assessment values (e.g., guidelinobjectives, standards) from other jurisdictions should evaluated for the chemicals for which insufficieninformation exists to proceed with the derivation oguidelines using the formal protocol. A sediment qualiassessment value should be adopted as an ISQG (usindefault process of MacDonald et al. 1992) until darequirements can be met for the formal protocol. Aassessment value from another jurisdiction may be adop(after comprehensive review) if it is scientifically defensiband the derivation process upon which it is basedconsistent with the CCME guiding principles. Arecommended by MacDonald et al. (1992), the three-tiesystem outlined below (modified from Beak Consultan1988) gives preference to biological-effect based values.

1. Select the lowest of the guidelines that incorporatdata on effects of sediment-associated chemicalssediment-dwelling organisms (i.e., the apparent effethreshold, screening level concentration, sedimequality triad, or NSTP approach), if any of these habeen or can be calculated.13eor

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2. For organic contaminants, select the lower vaobtained using the equilibrium partitioning and thwater quality guideline approaches (for which suitable Canadian water quality guideline exists) if neffect-based guidelines are available.

3. With respect to the development of site-specisediment quality objectives, select the uppbackground limit of a trace element if an interimguideline cannot be developed using either of tabove procedures or if it is below the upper bacground concentration for trace elements. (Although ttheoretical background concentrations of syntheorganic chemicals released into the environment aresult of human activities are zero, it may be necessto estimate ubiquitous levels of these substances frreference or clean sites located far from poinsources of contaminants).

The underlying rationale behind these recommendationthat the effect-based approaches rely directly on obseradverse biological effects of sediment-associated chemicThey are thought to be most ecologically relevant ascientifically defensible. Guidelines derived using thpartitioning methods are based only indirectly on biologiceffects (i.e., only to the extent that the water qualguidelines used in their calculations are effect-based). Dgaps are explicitly outlined in order to stimulate reseathat will generate the data necessary to develop SQGs uthe formal protocol.etfy theantedeis

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RECOMMENDATION OF CANADIANSEDIMENT QUALITY GUIDELINES

A Canadian SQG is recommended when the ISQG derivusing the NSTP approach is supported by a weight evidence of the available information that links the ISQG specific sediment types and/or characteristics of either sediments or of the overlying water column. A CanadiaISQG is recommended when the ISQG derived using NSTP approach is based on the available toxicologiinformation only (i.e., the minimum data requirements habeen met for an interim guideline, but the interim guidelincannot be linked to specific sediment types and/characteristics as is required for a full guideline). With respto ISQGs, data gaps are explicitly outlined in each guidelidocument to encourage the scientific community to generthe required information (e.g., information linking sedimetoxicity to sediment geochemical characteristics). SQGs walso be developed using the SSTT approach whmethodological questions are resolved.


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dedbutcs.llyibleingal toent),alityableofnt isceentAll of the available scientific information is evaluated inorder to support the recommendation of a Canadian Sor ISQG. The weight of evidence of toxicological datcompiled in the guideline derivation tables for eacchemical should support the assumption that the potenfor adverse biological effects of a substance increases wincreasing concentrations of the chemical. This evaluatis facilitated by the derivation of a second sedimequality assessment value (i.e., the probable effect levelPEL, above which adverse biological effects are usuaor always observed). This value, in conjunction with thISQG, is used to identify ranges in chemicaconcentrations associated with adverse biological effeand the incidence of adverse effects within each of theconcentration ranges. (See Appendix A for more detaThis evaluation provides an indication of the reliabilit(i.e., degree of confidence) in the guidelines establishand provides a means of estimating the probability observing similar adverse effects at sites with sedimechemical concentrations that fall within the defineconcentration ranges.

Contaminated benthos can introduce sediment contamininto the aquatic food web through predation by organisms ahigher trophic levels; therefore, the potential exists for thesubstances to be transferred through the food web (Lee1992). Because they are formulated from toxicologicinformation only, the SQGs and ISQGs derived using tNSTP approach and the SSTT approach do not specificaddress the potential for adverse effects on higher troplevels of the food chain as a result of the bioaccumulationpersistent toxic chemicals. Additional procedures will bused to adequately address these concerns. For examCanadian tissue residue guidelines for the protection wildlife consumers of aquatic life can be used, along wan appropriate bioaccumulation factor, to calculate SQthat would protect higher trophic levels.

For each substance, a report is produced summarizinginformation on its behaviour in sediments, the adverbiological effects associated with its presence in sements, and the rationale for the recommended guideliThese reports are reviewed by scientific experts in tfield, various federal departments (including NaturResources Canada, Environment Canada, the Departmof Fisheries and Oceans, Health Canada, Indian aNorthern Affairs Canada, Transport Canada, and PubWorks Canada), and the provinces through the CCMTask Group on Water Quality Guidelines. Upon approvby the CCME Task Group, the reports are submittedthe CCME Environmental Protection Committee and the Canadian Council of Ministers of the Environment fonational endorsement.1

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THE ROLE OF SEDIMENT QUALITYGUIDELINES

Sediment quality guidelines for the protection of aqualife are derived from the available toxicological information on the biological effects of sediment-associachemicals on aquatic organisms. The resulting guideliprovide scientific benchmarks to be used as a basis forevaluation, protection, and enhancement of sedimquality. These guidelines can help in setting targets sediment quality, within broader management strategthat will sustain aquatic ecosystem health for the loterm. As benchmarks, they can help to evaluate toxicological significance of sediment chemistry data, athus to identify and focus the cleanup of contaminasites, to predict the impacts of activities from variosectors (e.g., agriculture, forestry, and mining) on taquatic environment, and to evaluate the effectivenesproposed or existing management strategies in protecthe aquatic environment. In addition, they provide scientific review of the available toxicological informatiofor a chemical that can be used to support testablishment of sediment quality objectives to proteaquatic life, which are developed to reflect a numbersite-specific considerations. Whether the national SQGdefined as full or interim, it is used in a similarfashion. However, the limitations in the information useto derive SQGs and ISQGs should be acknowledged inapplications of the guidelines.

Sediment quality guidelines and the sediment toxicinformation compiled for each chemical provide common scientific basis for the establishment of sedimquality objectives. The objectives are developed to apdirectly to a particular site and consider a number distinct characteristics of that site, including chemicphysical (e.g., natural background concentrationgeochemical characteristics), and biological (e.g., sentive species) characteristics. The objectives are intento provide the same level of protection as the SQGs, take into account such site-specific characteristiEstablishment of sediment quality objectives usuarequires agreement between all of the parties responsfor managing the designated uses of the site. Dependon the circumstances at the site, an objective may be equthe national SQG, greater than the SQG (i.e., less stringor less than the SQG (i.e., more stringent). Sediment quguidelines and objectives that are recognized in enforceenvironmental control laws of one or more levels government are then defined as standards. A documecurrently under development to provide interpretive guidanon the use of national SQGs (C. Gaudet 1994, EnvironmCanada, Ottawa, pers. com.).4


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ns. issedrtgeidendseCanadian sediment quality guidelines are developed wthe intention to be conservative, since they are to be uon a national scale. Although SQGs are considered toapplicable to a variety of sediment types, they are intended to define uniform values of sediment quality onnationwide basis. However, they may be employas nationally consistent screening tools. There issignificant potential for differences in the bioavailabilit(and hence the toxicity) of contaminants in differesediment types. However, because of limitations in type of information currently available on the toxicity osediment-associated chemicals, it will be difficult to linthe guidelines to specific sediment types andcharacteristics associated with either the sediments oroverlying water column. Therefore, during thimplementation of these guidelines, caution should used in interpreting the biological significance of chemicconcentrations in sediments of different types characteristics from those compiled in the guideli15ithsed beot ada

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derivation tables for each chemical. The potential observing adverse biological effects, as indicated by exceedances of SQGs or ISQGs, must be evaluateconjunction with other information, such as naturbackground concentrations of substances, varibiological tests, and other assessment values (specificthe PEL). The use of SQGs in exclusion of this typeinformation can lead to erroneous conclusions predictions about ambient sediment quality conditioThe use of SQGs in conjunction with other informationbriefly discussed in Chapter 2. When SQGs are ualong with all other relevant information, they suppopractical and informed decision-making regardinsediment quality. In the future, field validation of thesguidelines at a variety of sites across Canada will prova means of evaluating their predictability in Canada, awill provide a basis for refining the guidelines to increatheir applicability in Canada, as necessary.t

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INTRODUCTION

Canadians have begun to recognize that developmeactivities represent potential hazards to the health aintegrity of their aquatic ecosystems. Fisheries closuresshellfish and advisories on finfish consumption in thvicinity of pulp mills in British Columbia provide graphicexamples of the potential social and economic impathat can result from the release of chemicals into tenvironment (M. Nassichuk 1992, Department Fisheriesand Oceans, Vancouver, pers. com.). The conservaand protection of our aquatic resources has become a hpriority goal, and management efforts are focusing reducing inputs of toxic substances into the environmeas well as cleaning up contaminated areas to restthe quality of degraded ecosystems (CEPA 198Government of Canada 1990).

Sediments are important in influencing the fate ochemicals in aquatic ecosystems and they provide habfor many benthic and epibenthic organisms. Concerregarding the protection and management of sedimquality have raised important questions about ttoxicological significance of sediment-associatechemicals and their potential to impair the designated uof aquatic environments. Therefore, SQGs for thprotection of aquatic life are needed to provide relevabenchmarks to help address these concerns.er 2uidelines as Benchmarks

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SQGs are only one of the many scientific tools availablto help in the protection and management of sedimequality. They can be used to help interpret whetheexisting or predicted sediment quality conditions pose threat to benthic organisms. The use of SQGs in exclusioof other information (such as background concentrationof naturally occurring substances, other assessment valusuch as the PEL, or biological tests) can lead to erroneoconclusions or predictions about sediment qualityTherefore, SQGs and all other relevant information shoube considered, to support practical and informed decisiomaking regarding sediment quality. These considerationare equally important whether the focus is to maintainprotect, or improve sediment quality conditions at aparticular site.

This chapter is intended to provide a brief generiexample of the use of national SQGs along with otherelevant information. The use of SQGs as nationabenchmarks provides a broadly applicable example fomany potential users of these guidelines and does nimply the preclusion of other specific uses that have nobeen discussed (such as their use with site-speciinformation and contaminant transport models to helevaluate discharge limits, their use to help focus thcleanup of contaminated sites, or as the scientific basis fdeveloping site-specific objectives). Potential applicationscenarios of SQGs, as well as guidance on when or how


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The following guidance is given within the context of general sediment assessment framework, which integrthe types of information that should be considered alowith SQGs. Specific management options, such defining site-specific objectives to maintain and protesediment quality conditions or defining remediatioobjectives to improve sediment quality conditions, cannbe appropriately chosen without an understanding ambient sediment quality. The framework provideenvironmental managers with a consistent process for uSQGs with other relevant information to assess sedimquality (i.e., to help answer the question of whether existor predicted concentrations of chemicals in sediment poshazard to sediment-associated organisms).fmdha

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inAPPLICATION OF SEDIMENT QUALITYGUIDELINES AS BENCHMARKS

Sediment quality guidelines can be used as benchmafor evaluating sediment chemistry information to identisituations that may be harmful to aquatic organisassociated with bed sediments. They can also be usebenchmarks to help set targets for sediment quality, witbroader management strategies, that will sustain aquecosystem health for the long term. The latter use will discussed more fully in a future document. For sedimeof superior quality, impairment to the national SQGshould not be advocated.

In using SQGs as benchmarks, adverse biological effeare not predicted when the measured concentrationssediment-associated chemicals at a site are at or belownational SQGs. (Note that the term site in the contextthis chapter is meant to be generic, whether it refers tregion, a basin, a specific site, or a given quantity sediment.) Further investigation of sediment quality at tsite is usually not necessary, but may be warranted unsome circumstances (e.g., when sediments at the site low levels of TOC, when other variables are suspectedbe increasing the bioavailability of chemicals, or wheSQGs do not exist for particular chemicals that ameasured in the sediment). The potential for observadverse biological effects is recognized when tconcentration of one or more sediment-associachemicals is greater than the national SQG, with tincidence and severity of these effects generaincreasing with increasing chemical concentrations (Loet al. 1994). (See also Appendix A.)1

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A GENERIC EXAMPLE

The context of a general sediment assessment is usedthe following sections to illustrate how SQGs function abenchmarks and how they should be used with othcomplementary information. A general framework providing an example of this is outlined in Figure 2. (Notthat this framework is not intended to replace acceptsediment-testing protocols or monitoring programs thhave already been established.) Depending on the goalthe assessment, various tools (e.g., SQGs, biological teand site-specific information (e.g., background concentrtions of naturally occurring substances) can be integratto achieve the desired goals. The components of thframework are briefly discussed in the following sections

In a broad context, the initial phase of a sediment qualassessment should involve the identification of sedimequality issues and concerns for the area that are primaassociated with (existing and/or potential) point annonpoint sources of contaminants. The goal of thassessment also needs to be clearly defined, includingaffirmation of the broader environmental managemegoal (of which sediment quality is only one componenthat has been defined for the region. A regionaassessment of sediment quality may be required determine the relative conditions of ambient sediments a number of sites, with the aim of prioritizing andfocusing future activities. In contrast, the assessment sediment quality at a specific site may need to charactersite conditions more comprehensively in order timplement specific management options (such as tmaintenance and/or protection of ambient sedimequality conditions, the development of site-specifiobjectives, or the potential remediation of an areaBesides being very different in geographical scale, thcomplexity of regional and site-specific sediment qualitassessments may vary depending on the situation. Ttypes of tools and information used in the assessmentultimately the choice of the environmental manager. Thfollowing sections provide a brief discussion on thvarious assessment tools available and the types of sspecific information that should be considered wheassessing sediment quality.

Water and Land Use Activities

The first step in the framework involves reviewingavailable information on existing and potential land anwater use for the site(s) under consideration. Informatioon past, present, and future industries and businesses6


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Effectspredicted

Existingdatainsufficient

Toxic ornot toxic

Anthropogenicorigin

Naturalorigin

Effects not predicted

Existingdatasufficient

May Conduct Bioassessmentto Verify Sediments not Toxic

Evaluate Sediment QualityManagement Options

Conduct Bioassessmentto Verify Predicted Toxicity

Evaluate Origin ofSediment-Associated Chemicals

(Natural vs. Anthropogenic)

Use SQGs to Identify Potentialfor Biological Effects

Collect SupplementalSediment Chemistry Data

Collect & Evaluate ExistingSediment Chemistry Data

Evaluate Existing/PotentialSources of Contaminants

Collect Historical Information

Figure 2. A framework for the assessment of sediment quality.


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tedata oftionibleey.ateuldthe area; the location of wastewater treatment plants; luse activities in upland areas; stormwater drainasystems; and residential developments is important. Sinformation provides a basis for identifying historicacurrent, and potential sources of contaminants to aquatic ecosystem. Information on the existing apotential chemical composition of point and nonpoisource discharges of contaminants, on the water quaconditions (in many cases, based on comparisons wwater quality guidelines), and on the physical/chemicproperties of these substances provides a basis identifying potential sediment chemistry concerns at tsite(s). Subsequently, a list of substances of potenconcern can be compiled. This site-specific information the past, present, and future uses of the site(s) prova basis for making decisions regarding the nature aextent of the investigations that should be conductMore detailed descriptions of the type of information thshould be collected and how such data can be usedassess ambient sediment quality is reviewed elsewh(Baudo and Muntau 1990; Mudroch and MacKnig1991; MacDonald 1993).

Existing Sediment Chemistry Data

All of the available sediment chemistry data for the siteunder consideration should be assembled to initiatepreliminary assessment of sediment quality conditionThe applicability of these data must be fully evaluateddetermine the overall quality of the existing data set, tdegree to which the data are thought to represent current conditions at the site(s), and the degree to whthey address the issues and concerns identified. addition, available information on other physical anchemical characteristics of the sediment (e.g., TOparticle size distribution) should be compiled in conjuntion with the data on chemical concentrations. Sufactors may influence the bioavailability (and hence ttoxicity) of sediment-associated chemicals, and the siteshould be assessed to determine the distinct conditithat exist.

An important consideration in the evaluation of the qualof the available sediment chemistry data is the quaassurance/quality control measures that were implemenduring collection, transport, and analysis of sedimesamples. Conventional practices have recently beestablished that provide guidance on the field aspectssediment sampling programs (ASTM 1990a; USEPA aACE 1991; Mudroch and MacKnight 1991; EnvironmeCanada 1994a). A diversity of analytical procedures habeen developed to quantify concentrations of chemicals1

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sediments, and acceptable methods have been repo(USEPA and ACE 1991). More novel analyticaprocedures may be evaluated based on the repoaccuracy and precision of the technique (i.e., the resultsanalyses performed on standard reference materials, samples, or spiked-sediment samples). The deteclimits reported must be relevant to assessing the potenfor biological effects at the site. The applicability of thdetection limits may be assessed by comparing them toSQGs recommended for that substance.

The applicability of existing sediment chemistry dashould also be evaluated in terms of temporal and spavariability in sediment quality. The age of the chemistdata is an important consideration. Natural degradatprocesses (Mosello and Calderoni 1990), meterologievents (such as storms) that result in the transportsediments (Allan 1986), industrial developments, aregulatory activities may alter the sources ancomposition of chemicals released into the environmeAs a result of these processes, historical chemical dmay not be representative of existing conditions. The of variables for which chemical analyses are completshould incorporate knowledge of the potential containants from land and water use activities in the area. Sithe chemistry of bed sediments may vary spatially (Mahal. 1989; Long and Morgan 1990; Hakanson 1992), dfrom a number of stations are required to providerepresentative picture of sediment quality conditions in area. The actual number of stations required will depeon the size of the area under consideration, the concentions of sediment-associated chemicals, the variabilitychemical concentrations, and the overall goal of tassessment.

If existing sediment chemistry data are considered acceptathe potential for observing adverse biological effects at site(s) can be assessed. If the sediment chemistry dataconsidered to be of unacceptable quality or are not considto adequately represent the site(s), additional sedimchemistry data should be collected.

Supplemental Sediment Chemistry Data

A focused, well-designed field survey must be implemento collect the types of supplemental sediment chemistry dthat will support the goal of the assessment. The initial listsubstances of potential concern defined during the evaluaof the land and water use activities provides a defensmeans of identifying substances for inclusion in a field survThe field survey should be designed to delinetemporal and spatial variability in sediment quality and sho8


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d iscses.anentexplicitly outline the quality assurance/quality contromeasures that will be implemented. Collection, handling, astorage of sediment samples should follow establishprotocols (ASTM 1990a; Environment Canada 1994Analytical methods and detection limits should be approprifor the substances under consideration.

The Potential for Adverse Biological Effects

The next step in the framework for assessing sedimquality involves determining the potential for observinadverse biological effects at the site(s) under considetion. Information on concentrations of chemicals sediments provides essential data for evaluating the naand spatial extent of sediment chemistry. However, thedata alone do not provide a measure of adverse biologeffects or an estimate of the potential for such effecSQGs are used to determine whether sediment-associchemicals are present at concentrations with the potento impair the aquatic life at that site(s).

As described in Chapter 1, a weight-of-evidence approais used to derive national SQGs. A second sedimquality assessment value, the PEL, can also be deriusing the guideline derivation tables (MacDonald 1993The PEL represents the lower limit of the range chemical concentrations that are usually or alwaassociated with adverse biological effects. The natioSQG and the PEL are used to define three rangeschemical concentrations for a particular chemical, thothat are rarely (PEL) associated wadverse biological effects (see Appendix A) (MacDona1993; Long et al. 1994). The quantification of thincidence of biological effects within each of thesconcentration ranges provides a useful tool for estimatthe probability of observing similar adverse effects withthe defined concentration ranges of particular chemicaTherefore, the frequency with which and degree to whimeasured sediment chemical concentrations at a sitewithin each of these concentration ranges are usefuldistinguish sites and chemicals of little toxicologicaconcern, of potential toxicological concern, or signifcantly hazardous to exposed organisms.

Sediments with measured chemical concentrations thatequal to or lower than the national SQGs are considerebe of acceptable quality. In general, further investigatioof these sediments would be of relatively low priorityManagement options at these sites would focus on protection of existing sediment quality conditionsHowever, in some cases, biological testing may 19lnded).te

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required for validation of this conclusion (for example, insediments with low levels of TOC, when other variableare suspected to be increasing the bioavailability sediment-associated chemicals, or when SQGs do nexist for particular chemicals that are measured in thsediment).

Sediments with measured chemical concentrationbetween the national SQG and the PEL are consideredrepresent potential hazards to exposed organismAlthough adverse biological effects are possible withithis range of concentrations, their occurrence, nature, aseverity are difficult to reliably predict on an a prioribasis. Specific conditions at these sites are likely control the expression of toxic effects. Further investigations on these sediments are needed to determine whesediment-associated chemicals represent significahazards to aquatic organisms. Such investigations minclude the determination of background concentrationfor naturally occurring substances and/or a suite biological tests designed to evaluate the toxicologicsignificance of particular chemicals (with respect to kespecies of aquatic biota and factors at the site that mayinfluencing the bioavailability of the chemical).

Sediments with measured chemical concentrations equal togreater than the PEL are considered to represent significand immediate hazards to exposed organisms. Sediments concentrations of one or more chemicals that fall within thrange of concentrations should be considered to be of highest priority for appropriate management actions improve sediment quality and restore the desired level protection, if necessary. Biological assessment is recomended at these sites to determine the nature and exteneffects that are being manifested as a result of the sedimassociated contaminants.

Background Concentrations of NaturalSubstances

The determination of background concentrations onaturally occurring substances is important when adverbiological effects have been predicted using SQGs (i.measured chemical concentrations at a site are >SQInformation on background concentrations of naturasubstances is used to determine the extent to which humactivities have contributed to the concentrations osediment-associated chemicals measured at a site, anparticularly important for metals and certain organisubstances that may be enriched through natural procesAlthough natural levels of these substances may have adverse effect on certain organisms, defensible managem


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entareundngthatnctyiesd toitelntoptions should consider the contribution of naturprocesses in order to focus on the sites and chemicalsare primarily influenced by human activities.

An interpretive tool has been developed that provideseffective means of distinguishing the probable origin (i.natural vs. anthropogenic) of many metals in sedime(Schropp and Windom 1988; Schropp et al. 1989; Lori1990, 1991; Schropp et al. 1990; Loring and Ranta1992). This method involves determining the ratio metal concentrations to those of a reference elemeBecause such ratios are relatively constant in the earcrust, they can be used to interpret the degree anthropogenic enrichment of metals at other locatioThis method has been demonstrated only for some masediments, however, and its applicability to freshwasediments is unknown (but should be evaluated).

The development and use of this interpretive tool involvintensive sampling at a number of uncontaminated swithin a region. For example, data on sediment meconcentrations were collected from roughly 100 sitesthr

protocol for the derivation of canadian sediment quality guidelines

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