Ecological Risk Ecological Risk AssessmentAssessment

MassDEP ORSMassDEP ORSTom AngusTom AngusGreg BraunGreg Braun

of Massachusetts Department

ENVIRONMENTAL PROTECTION

11

OverviewOverview1.1. Initial AssessmentInitial Assessment2.2. Stage I Ecological ScreeningStage I Ecological Screening3.3. Stage II Ecological Risk Stage II Ecological Risk

CharacterizationCharacterization4.4. Substantial Hazard EvaluationSubstantial Hazard Evaluation5.5. Sediment Risk ExampleSediment Risk Example6.6. Equilibrium Partitioning (EqP)Equilibrium Partitioning (EqP)

22

Ecological Ecological Risk CharacterizationRisk Characterization

Method 3Method 3

33

T = Technical Updatehttp://www.mass.gov/dep/service/compliance/riskasmt.htm

= Problem area

Method 3Method 3Method 3 is always an option.Method 3 is always an option. Should be used if:Should be used if:

There are COCs in sediment or There are COCs in sediment or surface water.surface water.

There are Bioaccumulating COCs.There are Bioaccumulating COCs. Neither Method 1 or 2 can be Neither Method 1 or 2 can be

used.used.

44

Ecological Risk Assessment: Ecological Risk Assessment: Process OverviewProcess Overview

Imminent Hazard

Readily Apparent

Harm

Stage I screening

Concentrations consistent

w/background or local

conditions?

Does site qualify for any size/habitat

quality exemptions?

Do concentrations exceed screening

criteria?

Stage II Risk Characterization

Problem Formulation

Conceptual Site ModelAssessment Endpoints

Risk AnalysisExposure &

effects assessment

Risk Characterization

Significant Risk?55

Stage I ScreeningInitial Assessment Stage II Risk Characterization

Imminent Hazard

Readily Apparent

Harm

Stage I screening66

Initial AssessmentInitial AssessmentMain Question: Is it clear w/o a quantitative risk

assessment that something must be done?

Imminent HazardImminent Hazard(310 CMR 40.0950)(310 CMR 40.0950)

Evidence of stressed Evidence of stressed biota including fish biota including fish kills or abiotic kills or abiotic conditions.conditions.

A release which A release which produces immediate produces immediate or acute adverse or acute adverse impacts.impacts.

Requires Immediate Requires Immediate Response Action.Response Action.

77

Readily Apparent Readily Apparent HarmHarm

(310 CMR 40.0995)(310 CMR 40.0995)• Visible evidence of sheens Visible evidence of sheens

or NAPL.or NAPL.• Visible evidence of Visible evidence of

stressed biota (e.g., fish stressed biota (e.g., fish kill).kill).

• OHM exceeds surface OHM exceeds surface water standards (NRWQC).water standards (NRWQC).

• Visible presence of oil, tar, Visible presence of oil, tar, NAPL in soil within 3’ of NAPL in soil within 3’ of surface.surface.

88

99

FLOCCULENT = READILY APPARENT HARM

1010FLOCCULENT = READILY APPARENT HARM

Stage IStage I Ecological ScreeningEcological Screening

1111

Stage I ScreeningStage I ScreeningMain Question: Are there any potentially

significant exposures?

Concentrations consistent

w/background or local conditions?

Does site qualify for any size/habitat quality

exemptions?

Do concentrations exceed screening criteria?

Stage II Risk Characterization 1212

Stage I ScreeningStage I Screening

No significant risk Risk is obvious

Stage I Screenin

g

Determine the need

for Stage II

Stage II not required Stage II not required

1313

Stage I Screening Stage I Screening OutcomesOutcomes

Stage II is Stage II is notnot required required There are no potentially There are no potentially

significant exposures/NSRsignificant exposures/NSR Significant Risk present Significant Risk present

Stage II Stage II isis required: required: Because it’s not clear if a Because it’s not clear if a

condition of NSR existscondition of NSR exists1414

Stage IStage I1. Habitat Quality 1. Habitat Quality

AssessmentAssessment

– – is the area a viable is the area a viable habitat?habitat? 1515

If Endangered, Threatened or species of If Endangered, Threatened or species of Special Concern are present, you have a Special Concern are present, you have a

viable habitatviable habitat

Northern Harrier - T

Braun’s Holly fern- E

Eastern Box Turtle-SC

Blue-Spotted Salamander-SC 1616

Undeveloped area < 2 acresUndeveloped area < 2 acres ExemptExempt

Undeveloped area 2 - 6 acresUndeveloped area 2 - 6 acres Depends; site specificDepends; site specific

Undeveloped area > 6 acresUndeveloped area > 6 acres Not exemptNot exempt

ACECs & areas with Threatened or ACECs & areas with Threatened or Endangered Species, or Species of Endangered Species, or Species of Special ConcernSpecial Concern Exemptions Do NOT applyExemptions Do NOT apply

Terrestrial Habitat Terrestrial Habitat QualityQuality

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Man-Made Water Man-Made Water BodiesBodiesFactors to Consider:Factors to Consider: Aquatic lifeAquatic life Bottom substrateBottom substrate Habitat valueHabitat value Area land useArea land use Management Management

practicespractices Hydraulic regimeHydraulic regime SizeSize

1818T

Sediment contamination may be Sediment contamination may be eliminated from the risk assessment eliminated from the risk assessment if the entire extent of the sediment if the entire extent of the sediment contamination is:contamination is:

< 1000 s.f., < 1000 s.f., andand < 10% of a small pond or < 10% of a small pond or < 10% of any ecological resource < 10% of any ecological resource

area (for example, 10% of the area (for example, 10% of the littoral zone) in a large pond or lake littoral zone) in a large pond or lake

Size Exemption - Lakes & Size Exemption - Lakes & PondsPonds

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Size Exemption – Rivers & Size Exemption – Rivers & StreamsStreams

Sediment contamination may be Sediment contamination may be eliminated from the risk assessment if eliminated from the risk assessment if the entire extent of the sediment the entire extent of the sediment contamination is less than 1000 s.f., contamination is less than 1000 s.f., andand

Does not extend more than 50% of the Does not extend more than 50% of the width of the river or stream, andwidth of the river or stream, and

Does not extend more than 500 linear Does not extend more than 500 linear feet along the length of the river or feet along the length of the river or stream.stream.

2020T

Stage IStage I2. Comparison to 2. Comparison to

Background or Local Background or Local ConditionsConditions

2121

BackgroundBackground Background reference locationBackground reference location::

Should have similar physical and Should have similar physical and habitat conditionshabitat conditions

Should be as close as possible Should be as close as possible w/o being impacted by site and w/o being impacted by site and in the same watershedin the same watershed

Sufficient sample size needed to Sufficient sample size needed to compare site and reference area compare site and reference area ((>>8 to compare statistically) 8 to compare statistically) Background concentrations of OHM

= NSR (310 CMR 40.1020) 2222

Local ConditionsLocal Conditions(an extension of background in sediment & (an extension of background in sediment &

S.W.)S.W.) COCs higher than background, COCs higher than background,

but ubiquitous near the site due but ubiquitous near the site due to sources other than the siteto sources other than the site

Contaminants from permitted Contaminants from permitted discharges, non-point sources discharges, non-point sources and other disposal sitesand other disposal sites

Must be assessed on a chemical Must be assessed on a chemical specific basisspecific basis

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SITE

2424

Stage IStage I3. Comparison to 3. Comparison to

Screening BenchmarksScreening Benchmarks

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BenchmarksBenchmarks Sediment: Sediment:

Probable Effects Concentrations (PECs)Probable Effects Concentrations (PECs) Threshold Effects Concentrations Threshold Effects Concentrations

(TECs) (TECs) Surface Water:Surface Water:

Massachusetts Surface Water Quality Massachusetts Surface Water Quality Standards (314 CMR 5.00)Standards (314 CMR 5.00) Standards based on USEPA National Standards based on USEPA National

Recommended Water Quality Criteria Recommended Water Quality Criteria (NRWQC(NRWQC))

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Sediment BenchmarksSediment Benchmarks Consensus-based guidelines Consensus-based guidelines

developed by MacDonald et al.(2000)developed by MacDonald et al.(2000) If the COC concentration is > PEC or If the COC concentration is > PEC or

TEC for any COC, a Stage II Risk TEC for any COC, a Stage II Risk Characterization must be done.Characterization must be done.

2727T

Sediment BenchmarksSediment Benchmarks Probable Effects Concentrations Probable Effects Concentrations

(PECs)(PECs) Concentrations above which adverse effects Concentrations above which adverse effects

are expected to occur more often than notare expected to occur more often than not Used for all metals except mercuryUsed for all metals except mercury

Threshold Effects Concentrations Threshold Effects Concentrations (TECs)(TECs) Concentration below which adverse effects Concentration below which adverse effects

are not expected to occurare not expected to occur Used for PAHs, PCBs, & mercuryUsed for PAHs, PCBs, & mercury 2828

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Surface Water Surface Water Benchmark DerivationsBenchmark Derivations USEPA National Recommended USEPA National Recommended

Water Quality Criteria (NRWQC)Water Quality Criteria (NRWQC) Chronic value should be used when Chronic value should be used when

availableavailable Sheens from OHM on surface waters Sheens from OHM on surface waters

are considered an exceedance of the are considered an exceedance of the Surface Water Quality Regulations Surface Water Quality Regulations and constitute Readily Apparent and constitute Readily Apparent HarmHarm

2929

Stage I Environmental Stage I Environmental ScreeningScreeningMain Question: Are there any potentially significant exposures?

Concentrations consistent

w/background or local

conditions?

Does site qualify for any size/habitat

quality exemptions?

Do concentrations exceed screening

criteria?

Stage II Risk Characterization

Low quality habitat

Habitat too small

Conditions ~background

Conditions ~local conditions

[COCs] < [Screening]

NOFURTHER ACTION

3030

Stage II Stage II Ecological Risk Ecological Risk

CharacterizationCharacterization

3131

Is an Ecological Is an Ecological Risk Risk

Assessor Assessor involved?involved?

3232

Stage II Ecological Risk Stage II Ecological Risk CharacterizationCharacterization

Problem FormulationConceptual Site ModelAssessment Endpoints

Risk AnalysisExposure & effects

assessment

Risk Characterization

Significant Risk?3333

Main Question: Is there significant risk at the site?

Ecological Risk Assessment Decision Diagram for Contaminated Sediment

Concentrations Consistent with Background?

Stage I: Contamination > Screening Criteria?

Imminent Hazard?

Readily Apparent Harm?

Stage II: Significant Risk?

“No Significant Risk” Feasible?

Remediate

No Significant Risk/Permanent Solution

Substantial Hazard?

Remediate

Temporary Solution

Remediate

YES

No

No

No

No

No

No

No

YES

YES

YES

YES

YES

YES

YES

YES

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Problem FormulationDevelop Conceptual Site Model

Risk Analysis Exposure

CharacterizationEffects

Characterization

Risk Characterization

Risk Management and Communication

Acquire data, iterate process, m

onitor results

Ecological Risk Assessment Framework

Identify Assessment Endpoints

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The measurement step

Stage IIStage IIProblem Formulation Problem Formulation

3636

“A problem well defined is a problem half solved.” – John Dewey

Problem FormulationProblem Formulation Identify the ecological resources Identify the ecological resources

you want to assess to determine you want to assess to determine if there is an ecological impact.if there is an ecological impact.

What species should be the focus What species should be the focus of the ecological risk assessment?of the ecological risk assessment?

Develop Conceptual Site Model Develop Conceptual Site Model (CSM)(CSM)

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Stage IIStage IIProblem FormulationProblem Formulation

Developing Conceptual Site Developing Conceptual Site Model Model

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Conceptual Site Model :Conceptual Site Model :

Contaminants & SourcesContaminants & Sources Fate & Transport of COCsFate & Transport of COCs ReceptorsReceptors Exposure PathwaysExposure Pathways

A visual and/or narrative representationof the links between:

3939

A good CSM can help…A good CSM can help… The risk assessor ask questions The risk assessor ask questions

pertinent to the site.pertinent to the site. Guide data collection.Guide data collection. Inform the exposure Inform the exposure

assessment.assessment. Put data into context to better Put data into context to better

characterize risk.characterize risk.4040

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4242

Developing CSMDeveloping CSM CSMs are an iterative toolCSMs are an iterative tool Site Reconnaissance is criticalSite Reconnaissance is critical Should include all COCs, sources, Should include all COCs, sources,

routes of exposure and receptors routes of exposure and receptors that could be of concernthat could be of concern

Pathways should only be eliminated Pathways should only be eliminated if there is high confidence that if there is high confidence that pathway is incompletepathway is incomplete

4343

Conceptual Site Models – Conceptual Site Models – Common ProblemsCommon Problems

The most common problem with The most common problem with CSMs is that they are not done or CSMs is that they are not done or not integrated into the process.not integrated into the process.

Exposure pathways ignored or Exposure pathways ignored or overlooked.overlooked.

CSMs that do not incorporate CSMs that do not incorporate how chemicals were applied how chemicals were applied often overlook important fate often overlook important fate and transport mechanisms.and transport mechanisms.

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Stage IIStage IIProblem FormulationProblem Formulation

Identify Assessment EndpointsIdentify Assessment Endpoints

4545

Assessment EndpointsAssessment Endpoints

4545

Assessment endpoint – effects on Assessment endpoint – effects on an organism(s) that can be an organism(s) that can be measured.measured.

Example: Example: Survival, growth & Survival, growth & reproduction of Largemouth Bassreproduction of Largemouth Bass

Selecting Assessment Selecting Assessment Endpoint SpeciesEndpoint Species

Be sensitive to OHM presentBe sensitive to OHM present Represent the most Represent the most

susceptible feeding strategysusceptible feeding strategy Provide key ecological Provide key ecological

functions, or represent a functions, or represent a group that doesgroup that does

Be measureableBe measureable 4747

Assessment Endpoints should:

Challenges of Assessment Challenges of Assessment Endpoint Selection Endpoint Selection

Large number of exposed Large number of exposed species in most habitats.species in most habitats.

Limited data on natural Limited data on natural history and exposure history and exposure pathways.pathways.

Endpoint selection is often Endpoint selection is often “tool driven”.“tool driven”.

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Amphibians often not Amphibians often not assessedassessed

4949

MudpuppyJefferson SalamanderBlue-spotted SalamanderSpotted SalamanderMarbled SalamanderEastern NewtNorthern Dusky SalamanderEastern Red-backed SalamanderFour-toed SalamanderNorthern Two-lined SalamanderEastern SpadefootAmerican ToadFowler's ToadSpring PeeperGray TreefrogAmerican BullfrogGreen FrogPickerel FrogNorthern Leopard FrogWood Frog

Assessment Endpoint?Assessment Endpoint?

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Assessment Endpoint Assessment Endpoint ExamplesExamples

5151

Site with widespread PCB Site with widespread PCB releases:releases: Survival and reproduction Survival and reproduction

of piscivorous mammal of piscivorous mammal (Mink)(Mink)

Site with localized metal Site with localized metal releases:releases: Survival and reproduction Survival and reproduction

of insectivorous bird of insectivorous bird (swallows)(swallows)

Stage IIStage IIRisk Analysis Risk Analysis

Exposure Characterization Exposure Characterization & Effects Characterization& Effects Characterization

5252

Risk AnalysisRisk Analysis Evaluate measurement endpointsEvaluate measurement endpoints Collect & Integrate information:Collect & Integrate information:

ToxicityToxicity ConcentrationsConcentrations Spatial distribution of COCsSpatial distribution of COCs ExposuresExposures ObservationsObservations

5353

Stage IIStage IIRisk Characterization Risk Characterization

5454

Risk Risk CharacterizationCharacterization

Evaluate all the available data to Evaluate all the available data to determine if it supports a conclusion of determine if it supports a conclusion of no significant risk for each assessment no significant risk for each assessment endpoint.endpoint.

More than one measurement endpoint?More than one measurement endpoint? Weight of evidence approachWeight of evidence approach Lines of evidenceLines of evidence

5555

Three Lines of Evidence in a Sediment Risk Assessment

5656

Weight of EvidenceWeight of EvidenceWhen comparing 2 or more measurementendpoints be aware that not all measurement endpoints are created equal

5757

If risk is significant but a If risk is significant but a permanent solution is not permanent solution is not feasible, then a Substantial feasible, then a Substantial Hazard Evaluation (40.0956) Hazard Evaluation (40.0956) must be completed.must be completed.

By definition a temporary By definition a temporary solution must eliminate any solution must eliminate any Substantial Hazards.Substantial Hazards.

5858

After the Risk Assessment After the Risk Assessment Substantial HazardSubstantial Hazard

To achieve Condition of No To achieve Condition of No Substantial Hazard to the Substantial Hazard to the

Environment:Environment: Steps must be taken to eliminate Steps must be taken to eliminate

or mitigate:or mitigate: Evidence of stressed biota;Evidence of stressed biota; OHM within 3 feet of the soil surface OHM within 3 feet of the soil surface

or within 1 foot of sediment surface;or within 1 foot of sediment surface; Continuing discharge of Continuing discharge of

contaminated groundwater to contaminated groundwater to surface water or sediment;surface water or sediment;

Migration of OHM to additional Migration of OHM to additional environmental media.environmental media.

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ECOLOGICAL RISK ECOLOGICAL RISK CHARACTERIZATIOCHARACTERIZATIO

N- SEDIMENT N- SEDIMENT EXAMPLE EXAMPLE

6161

6262

ASSESSMENTENDPOINTS -

BENTHIC INVERTEBRATEEXAMPLE

Amphipod (scud) Isopods (aquatic sowbugs) Decopod (crayfish)

Benthic Macroinvertebrates Must Be Evaluated

In Addition To Other Appropriate Receptors

Molluscs (snails)

Ephemoptera (mayfly)Trichoptera (caddisfly)

6363

Benthic Invertebrate Benthic Invertebrate Assessment EndpointsAssessment Endpoints

Survival, growth and reproductionSurvival, growth and reproduction Should be evaluated in all casesShould be evaluated in all cases

Community ConditionCommunity Condition Can provide supporting informationCan provide supporting information

6464T

6565

MEASURES OF EFFECTS -

SEDIMENT EXAMPLE

1. 1. Benchmarks Benchmarks - generally - generally conservative, should be included as conservative, should be included as a point of reference.a point of reference.

2. 2. Toxicity testing Toxicity testing – ORS considers – ORS considers this the most reliable measure.this the most reliable measure.

3. 3. Benthic Community Survey Benthic Community Survey – useful – useful but expensive if done right.but expensive if done right.

6666

Measurements of Measurements of EffectsEffects

T

Measures of Effects in Relation Measures of Effects in Relation toto

Assessment EndpointsAssessment Endpoints Survival, Growth & ReproductionSurvival, Growth & Reproduction

BenchmarksBenchmarks Sediment toxicity testingSediment toxicity testing

Community AssessmentCommunity Assessment Benthic community field surveysBenthic community field surveys

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6868

1. SEDIMENT BENCHMARKS -

SEDIMENT EXAMPLEPublished sediment concentrations based on large empirical data sets

T

Sediment Benchmark Sediment Benchmark Selection Selection

Values published by government Values published by government agencies preferredagencies preferred

e.g., Threshold Effects Level (TEL)e.g., Threshold Effects Level (TEL) NOAA SQuiRTs – a good resourceNOAA SQuiRTs – a good resource

http://response.restoration.noaa.gov/book_shelf/122_NEW-SQuiRTs.pdf

Other options require more justification:Other options require more justification: Single study benchmarksSingle study benchmarks Benchmarks derived using equilibrium Benchmarks derived using equilibrium

partitioning calculationspartitioning calculations Site-specific derived benchmarkSite-specific derived benchmark

6969

Benchmark Red FlagsBenchmark Red Flags No benchmarksNo benchmarks The use of non-agency published The use of non-agency published

benchmarks with no supporting benchmarks with no supporting documentation.documentation.

Large exceedances not flagged Large exceedances not flagged as significant risk. as significant risk.

““Cherry Picking” the highest Cherry Picking” the highest benchmark values.benchmark values.

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2. SEDIMENT TOXICITY TESTING -SEDIMENT EXAMPLEThis is where we take a bunch of sediment from the field into the lab and expose test

organisms to the sediment for a period of time under pre-defined laboratory conditions.

T

Chironomus tentansChironomus tentans - - InsectInsect

USEPA Test Method USEPA Test Method 100.5 100.5 Chironomus Chironomus tentans tentans life cycle life cycle test for survival, test for survival, growth, growth, reproduction & reproduction & developmentdevelopment

7272

Hyalella aztecaHyalella azteca - - amphipodamphipod

USEPA Test USEPA Test Method 100.4 Method 100.4 Hyalella azteca Hyalella azteca 42-day chronic 42-day chronic tests for survival, tests for survival, growth, and growth, and reproductionreproduction

7373

Sediment Toxicity Sediment Toxicity Testing Testing

Direct method for assessing toxicity of Direct method for assessing toxicity of sediment to benthic invertebrates.sediment to benthic invertebrates.

Test Length:Test Length: Short-term: Not RecommendedShort-term: Not Recommended

e.g., 10-day survival test with chironomide.g., 10-day survival test with chironomid Medium-term: RecommendedMedium-term: Recommended

e.g., 28-day growth test with Hyallelae.g., 28-day growth test with Hyallela Longer-term: RecommendedLonger-term: Recommended

e.g., 42-day reproduction test with Hyallelae.g., 42-day reproduction test with Hyallela

7474

Looking at Sediment Looking at Sediment Toxicity Test ResultsToxicity Test Results

28-Day amphipod test at coal tar site:28-Day amphipod test at coal tar site: Four reference samples:Four reference samples:

68%, 73%, 73%, and 90% survival68%, 73%, 73%, and 90% survival Six Site SamplesSix Site Samples

Two site samples with no statistically significant Two site samples with no statistically significant difference:difference:

43% and 58% survival43% and 58% survival Four site samples with a statistically significant Four site samples with a statistically significant

difference:difference: 0%, 0%, 0%, and 10% survival0%, 0%, 0%, and 10% survival

7575

Sediment Toxicity Sediment Toxicity Testing Red FlagsTesting Red Flags

High toxicity in reference samples can High toxicity in reference samples can complicate comparison between site complicate comparison between site toxicity and reference toxicity.toxicity and reference toxicity.

10-day tests used instead of longer tests.10-day tests used instead of longer tests. Less expensive but less sensitiveLess expensive but less sensitive

Reproductive endpoint is often skipped, Reproductive endpoint is often skipped, increasing uncertainty about risk.increasing uncertainty about risk.

Small sample size increases uncertainty.Small sample size increases uncertainty.

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3. BENTHIC COMMUNITY SURVEYS -

SEDIMENT EXAMPLE

Benthic Invertebrate Benthic Invertebrate SurveysSurveys

Evaluate invertebrate Evaluate invertebrate community structurecommunity structure

Collect samples from Collect samples from contaminated areas contaminated areas and reference areasand reference areas

Sieve samples Sieve samples Submit to lab for Submit to lab for

identificationidentification

7878

Benthic Invertebrate Benthic Invertebrate SurveysSurveys

Samples are Samples are compared using compared using abundance and abundance and diversity measuresdiversity measures

Site samples are Site samples are compared to compared to reference areasreference areas

7979

BENTHIC MACROINVERTEBRATE SURVEY

TAXONFeeding Group HBI

STATIONReference Area

Property 20Hells 1/2 Acre Greenough Blvd ref1 ref2 ref3 ref4 ref5 ref6 AVE sd-14 sd-15 AVE

ANNELIDA OLIGOCHAETA ENCHYTRAEIDAE GC 10 4 2 ANNELIDA OLIGOCHAETA TUBIFICAIDAE GC 10 38 272 ANNELIDA OLIGOCHAETA NAIDIDAE GC 9 2 BIVALVA BIVALVA FC 80 BIVALVA VENEROIDA SPHAERIIDAE FC 8 40 54 GASTROPODA BASOMMATOPHORA PHYSIDAE GC 8 1 1 16 GASTROPODA BASOMMATOPHORA PHYSA SP. GC 1 2 INSECTA COLLEMBOLA COLLEMBOLA GC 1 INSECTA DIPTERA CHIRONOMIDAE GC 8 2 14 3 3 76 10 INSECTA TIPULOIDEA TIPULIDAE SH 2 NEMATODA NEMATODA PA 6 4

Total Abundance: 2 14 3 1 1 5 4.3 182 426 304

Total Number of Taxa: 1 1 1 1 1 3 7 8

Number of Discrete Taxa: 1 1 1 1 1 2 6 7 Feeding Group:

GC = gatherer/collectorFC = filterer/collectorPR = predatorSH = shredderPA = parasite

HBI = Hilsenhoff Biotic Index; Measure of Tolerance/Intolerance (1 = low tolerance; 10 = high tolerance)

Benthic Invertebrate Survey Example

8080

Benthic Invertebrate Benthic Invertebrate SurveysSurveys

Red FlagsRed Flags Few samples saves money but Few samples saves money but

increases uncertainty. increases uncertainty. Inappropriate reference area Inappropriate reference area

selection. selection. Reference area impacted by other Reference area impacted by other

stressors or habitat quality not stressors or habitat quality not equivalent to site. equivalent to site.

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Risk Characterization Risk Characterization Recommendations Recommendations

Consider 3 measures of effect:Consider 3 measures of effect: Benchmarks, toxicity tests, community surveysBenchmarks, toxicity tests, community surveys

At a minimum, benchmarks and toxicity At a minimum, benchmarks and toxicity tests should be includedtests should be included

Toxicity tests are generally:Toxicity tests are generally: More accurate than benchmark comparisonsMore accurate than benchmark comparisons More conclusive than benthic invertebrate More conclusive than benthic invertebrate

surveys surveys

8282

Equilibrium Partitioning-Based Equilibrium Partitioning-Based Approaches for Sediment Approaches for Sediment

AssessmentAssessment

8383

Emerging Technical Issues Related Emerging Technical Issues Related to Equilibrium Partitioning (EqP)to Equilibrium Partitioning (EqP)

Underlying TheoryUnderlying TheoryAVS/SEM to Evaluate Metals in SedimentAVS/SEM to Evaluate Metals in SedimentEvaluation of Petroleum ContaminationEvaluation of Petroleum ContaminationProtection of Sediment-Ingesting Protection of Sediment-Ingesting Benthic OrganismsBenthic Organisms

Passive SamplersPassive Samplers

8484

Why Does This Matter?Why Does This Matter? EqP is increasingly used for eco risk EqP is increasingly used for eco risk

assessments.assessments. Ecological risk/harm may be Ecological risk/harm may be

underestimated if underlying underestimated if underlying assumptions are not valid.assumptions are not valid.

LSPs need to recognize when:LSPs need to recognize when: Approach may not be validApproach may not be valid Interpretation of results may not be validInterpretation of results may not be valid

8585

Benthic Invertebrate Exposures to Pore Water

(Not to Scale!)

amphipod

8686

General EqP General EqP AssumptionsAssumptions

Exposure and toxicity are determined Exposure and toxicity are determined by the pore water concentrationby the pore water concentration

Pore water concentration is Pore water concentration is determined by: determined by: the bulk sediment concentration the bulk sediment concentration the percent of organic carbon in the percent of organic carbon in

sedimentsediment the affinity of the contaminant for the affinity of the contaminant for

organic carbonorganic carbon

8787

Basic EqP EquationBasic EqP EquationCsed = foc x Koc x Cw Csed = foc x Koc x Cw

Where:Where:

Csed Csed = = sediment concentrationsediment concentrationfocfoc == fraction organic carbonfraction organic carbonKoc Koc = = organic carbon:water partition organic carbon:water partition

coefficientcoefficientCw Cw = = pore water concentrationpore water concentration

USEPA (2003) ESB ApproachUSEPA (2003) ESB Approach

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Equilibrium Partitioning Equilibrium Partitioning and Acid Volatile and Acid Volatile

Sulfide-Simultaneously Sulfide-Simultaneously Extracted Metals Extracted Metals

USEPA 2005 EPA-600-R-02-USEPA 2005 EPA-600-R-02-011011

8989

AVS-SEM TheoryAVS-SEM Theory Divalent metals (cadmium, copper, Divalent metals (cadmium, copper,

lead, nickel, silver, and zinc) are lead, nickel, silver, and zinc) are bound to sulfide minerals, reducing bound to sulfide minerals, reducing bioavailabilitybioavailability

When: When: Metals < AVS, no risk, orMetals < AVS, no risk, or

∑ ∑ii[SEM[SEMii] < [AVS]] < [AVS] Metals < Water Toxicity Values, no riskMetals < Water Toxicity Values, no risk

∑∑ii [M [Mi,di,d]/FCV]/FCVi,di,d < 1 < 1

9090

AVS-SEM AVS-SEM General CautionsGeneral Cautions

Conditions change over time and Conditions change over time and spacespace

Measurements include non-metal Measurements include non-metal binding sulfidebinding sulfide

Based on acute rather than chronic Based on acute rather than chronic effectseffects

Does not consider bioaccumulationDoes not consider bioaccumulation Only evaluates six metalsOnly evaluates six metals

9191

Interlaboratory Variability Interlaboratory Variability in AVS-SEM Measurementsin AVS-SEM Measurements

A study compared analysis from A study compared analysis from seven laboratories:seven laboratories:

For the same samples, AVS For the same samples, AVS varied by a factor of 10-1000 for varied by a factor of 10-1000 for each of four study sediments.each of four study sediments.

SEM varied a factor of 20-50 SEM varied a factor of 20-50 among the labs for each of the among the labs for each of the four samples. four samples.

9292

AVS/SEM: AVS/SEM: ORS ConclusionsORS Conclusions

AVS/SEM should be confirmatory AVS/SEM should be confirmatory evidence, and should not be evidence, and should not be used to overrule lines of used to overrule lines of evidence.evidence.

AVS/SEM data are given a low AVS/SEM data are given a low priority for collection, low weight priority for collection, low weight in weight of evidence.in weight of evidence.

9393

EqP-derived PAH sediment EqP-derived PAH sediment benchmarks as Indicators of benchmarks as Indicators of

Petroleum ToxicityPetroleum Toxicity

9494

PAHs and Petroleum ToxicityPAHs and Petroleum Toxicity Using EqP, the toxicity of petroleum has Using EqP, the toxicity of petroleum has

been attributed to PAHs, but recent EPA been attributed to PAHs, but recent EPA research suggests:research suggests: Toxicity may occur with weathered oils with Toxicity may occur with weathered oils with

low PAH content (e.g., lubricating oils)low PAH content (e.g., lubricating oils) Assessing toxicity of low PAH oils based on Assessing toxicity of low PAH oils based on

PAH concentrations will greatly PAH concentrations will greatly underestimate toxicityunderestimate toxicity

EPA PAH EqP benchmarks do not account for EPA PAH EqP benchmarks do not account for other petroleum componentsother petroleum components

9595

Physical Effects of Non-PAH Physical Effects of Non-PAH Petroleum ComponentsPetroleum Components

SmotheringSmothering Impaired movement Impaired movement

and feedingand feeding Habitat destructionHabitat destruction Reduction in the Reduction in the

sediment aerobic layersediment aerobic layer Increased organic Increased organic

enrichmentenrichment9696

Readily Apparent HarmReadily Apparent Harm(MCP Approach to Petroleum (MCP Approach to Petroleum Hydrocarbon Physical Effects)Hydrocarbon Physical Effects)

The MCP defines visible The MCP defines visible presence of oil or tar over presence of oil or tar over greater than 1000 square greater than 1000 square feet within one foot of the feet within one foot of the sediment surface as sediment surface as significant risk significant risk (310 CMR 40.0995(3)(b))(310 CMR 40.0995(3)(b))

This accounts for risks This accounts for risks from physical effects of from physical effects of petroleumpetroleum

9797

Sediment Ingesters Sediment Ingesters and Organic Chemicalsand Organic Chemicals

9898

EqP Theory May Not Address EqP Theory May Not Address Sediment IngestersSediment Ingesters

Freshwater sediment ingesters can Freshwater sediment ingesters can constitute most of the benthic community.constitute most of the benthic community.

Rates of sediment ingestion can be Rates of sediment ingestion can be greater than 100 times body weight per greater than 100 times body weight per dayday

If sediment ingestion drives exposure, EqP If sediment ingestion drives exposure, EqP is not protectiveis not protective

For contaminants with log Kow>5, For contaminants with log Kow>5, sediment ingestion drives exposuresediment ingestion drives exposure

Lumbriculus

juvenilechironomus 9999

Method 1 Organic Chemicals Method 1 Organic Chemicals With Log Kow > 5With Log Kow > 5

8 of the 16 PAHs8 of the 16 PAHs Pesticides such as DDD, DDE, Pesticides such as DDD, DDE,

DDT, and MethoxychlorDDT, and Methoxychlor HexachlorobenzeneHexachlorobenzene PentachlorophenolPentachlorophenol PhthalatesPhthalates PCBsPCBs 2,3,7,8-TCDD2,3,7,8-TCDD

100100

Petroleum Take-Home Petroleum Take-Home MessagesMessages

EqP does not protect sediment EqP does not protect sediment ingesters when high Kow PAHs ingesters when high Kow PAHs are present.are present.

EqP does not consider the EqP does not consider the toxicity of non-PAH components toxicity of non-PAH components of petroleum.of petroleum.

EqP is only a single line of EqP is only a single line of evidence.evidence.

Use EqP approaches for Use EqP approaches for petroleum with caution.petroleum with caution. 101101

EqP and Passive EqP and Passive SamplersSamplers

102102

Sediment Passive Sediment Passive SamplersSamplers

Various plastics used as a Various plastics used as a surrogate for aquatic organisms.surrogate for aquatic organisms.

Rely on diffusion of chemicals Rely on diffusion of chemicals from sediment to the sampler to from sediment to the sampler to reach equilibrium.reach equilibrium.

Used to mimic benthic organism Used to mimic benthic organism absorption of hydrophobic absorption of hydrophobic organic chemicals (e.g., PCBs).organic chemicals (e.g., PCBs).

103103

Water Column

50 u

m

Passive Sampler(e.g., Low Density

Polyethylene Device)Initial concentration of PCBs in

passive samplers = 0 ng/mL

Passive Sampler TheoryPassive Sampler TheoryPCB molecule

From: R. Burgess, USEPA104104

Deployment Time (days)

Con

cent

ratio

n(n

g/m

L P

assi

ve S

ampl

er)

Apparent equilibriumor steady-state

*

Passive Sampler TheoryPassive Sampler Theory

From: R. Burgess, USEPA105105

Types of Passive SamplersTypes of Passive Samplers

fiber-optic cable

50 um thick

polyethylenesheet0.

25 m

Polyethylene tubing

(70-95 um thick)

2.5 cm

From: R. Burgess, USEPA 106106

Passive SamplersPassive SamplersPoly Ethylene Device (PED)

(URI-GSO)

From: R. Burgess, USEPA107107

Semi-Permeable Membrane Device (SPMD)

Issues using Passive Issues using Passive SamplersSamplers

Determining absorption-Determining absorption-diffusion equilibrium is difficultdiffusion equilibrium is difficult Determining when equilibrium Determining when equilibrium

occursoccurs Relating sampler Relating sampler

accumulation to animal accumulation to animal bioaccumulationbioaccumulation

108108

MassDEPMassDEPOffice of Research and StandardsOffice of Research and Standards

One Winter Street One Winter Street Boston MA 02108Boston MA 02108

Tom AngusTom Angus(617) 292-5513(617) 292-5513

Thomas.Angus@state.ma.usGreg BraunGreg Braun

(617) 292-5718(617) 292-5718Greg.Braun@state.ma.us

109109