Download - Ecological Risk Assessment
Ecological Risk Ecological Risk AssessmentAssessment
MassDEP ORSMassDEP ORSTom AngusTom AngusGreg BraunGreg Braun
of Massachusetts Department
ENVIRONMENTAL PROTECTION
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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)
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Ecological Ecological Risk CharacterizationRisk Characterization
Method 3Method 3
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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.
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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.
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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.
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FLOCCULENT = READILY APPARENT HARM
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Stage IStage I Ecological ScreeningEcological Screening
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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
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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
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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.
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Stage IStage I2. Comparison to 2. Comparison to
Background or Local Background or Local ConditionsConditions
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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
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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.
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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
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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
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Stage II Stage II Ecological Risk Ecological Risk
CharacterizationCharacterization
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Is an Ecological Is an Ecological Risk Risk
Assessor Assessor involved?involved?
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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
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“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:
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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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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
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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
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Assessment EndpointsAssessment Endpoints
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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
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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
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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
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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
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Stage IIStage IIRisk Characterization Risk Characterization
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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
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Three Lines of Evidence in a Sediment Risk Assessment
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Weight of EvidenceWeight of EvidenceWhen comparing 2 or more measurementendpoints be aware that not all measurement endpoints are created equal
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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.
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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
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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)
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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
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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.
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Measurements of Measurements of EffectsEffects
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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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1. SEDIMENT BENCHMARKS -
SEDIMENT EXAMPLEPublished sediment concentrations based on large empirical data sets
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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
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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.
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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
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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
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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
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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
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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
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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
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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
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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
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Equilibrium Partitioning-Based Equilibrium Partitioning-Based Approaches for Sediment Approaches for Sediment
AssessmentAssessment
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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
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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
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Benthic Invertebrate Exposures to Pore Water
(Not to Scale!)
amphipod
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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
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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
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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
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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
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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.
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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.
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EqP-derived PAH sediment EqP-derived PAH sediment benchmarks as Indicators of benchmarks as Indicators of
Petroleum ToxicityPetroleum Toxicity
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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
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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
[email protected] BraunGreg Braun
(617) 292-5718(617) [email protected]
109109