Linking Fish and Wildlife Tissue Residues to Contaminant Concentrations in Water and Sediment

Transcription

1 Linking Fish and Wildlife Tissue Residues to Contaminant Concentrations in Water and Sediment Perspectives on Regulatory Criteria and Screening Levels Based on Wildlife Tissue Residues SETAC Hudson/Delaware Chapter October 8, 2008

2 Introduction Developing the linkage between tissue levels and water is necessary, because: Clean Water Act Water quality criteria NPDES permits TMDLs Contaminated sediments Superfund Remedy design

3 How Is the Linkage Performed? BAF simple ratio National, GLI Site-specific Computer simulation model Steady state vs. dynamic Mechanistic vs. statistical Bioaccumulation, chemical fate and transport, sediment transport, hydrodynamics

4 Examples of the Linkage Water quality criteria to protect wildlife s - Great Lakes Initiative Water quality criteria to protect human health Draft guidance for site-specific BAFs and BSAFs (June 2008) Water quality criterion to protect human health for PCBs Water quality criteria for selenium effects on aquatic life Chronic criterion is tissue-based EPA developing method to translate to water concentration Contaminated sediment remedial design Computer simulation models: Hudson, Housatonic, Fox River, Passaic Rivers Management of Material from Navigational Dredging CARP model

5 Definitions Bioaccumulation Factor (BAF) = C biota /C water Water: dissolved Biota usually lipid-normalized for organics BCF Trophic transfer Bioconcentration Factor (BCF) = Biota/water Water only exposure BCF Trophic transfer BAF Biota Sediment Accumulation Factor (BSAF) = C biota /C sediment Sediment: carbon-normalized Biota: lipid-normalized BCF Dissolved chemical

6 Contents of the Rest of the Talk Description of methods to estimate BAFs Site-specificity of BAFs and BSAFs Considerations when measuring a BAF in the field Issues associated with the linkage Consistency between regulatory endpoints Necessity of achieving water quality criteria for meeting risk-based goals Achievability of water quality criteria Site-specificity for nonionic organics and for other chemicals

7 Methods to Estimate BAFs EPA (2008). Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health (2000) Draft Technical Support Document Volume 3: Development of Site-Specific Bioaccumulation Factors Describes 5 methods of estimating site-specific BAFs

8 Methods to Estimate BAFs Method 1: Field-measured BAF contemporaneous co-located biota and water data L/kg lipid Bioaccumulation factors for PCB congeners: walleye in Green Bay, zone 3b Log Kow

9 Methods to Estimate BAFs Method 2: BAFs computed from field-measured BSAFs BAF = BSAF concentration in sediment concentration in water

10 Method 2: Sediment/Water Ratio Ratio of sediment/water concentrations of PCB congeners and homologs Varies significantly among water bodies

11 Methods to Estimate BAFs Method 3: Extrapolation from BSAFs and BEFs 3a: Extrapolated BSAFs 3b: Bioaccumulation equivalence factors (BEFs) measured at reference site BSAF C = BSAF Cref BSAF BSAF C, ref site Cref, ref site

12 Methods to Estimate BAFs Method 4: Calculation from BCF X FCM BCF: 4a: Laboratory-measured 4b: Estimated using K OW FCM: Based on field data Calculated from steady state bioaccumulation model Trophic transfer factors for PCB congeners: walleye/forage fish in Green Bay, zone 3b

13 Method 4: Trophic Transfer Total PCBs, Hudson River Forage to predatory fish: relatively little variation consistent over time

14 Methods to Estimate BAFs Method 5: National or baseline BAFs Adjust using local lipid content and/or organic carbon concentration t T BAF = f [1 + fd ( f l )( BAF fd L )] Total BAF: Wet weight-normalized in fish, Total in water Baseline BAF: lipid-normalized in fish, dissolved in the water

15 BAFs and BSAFs Are Site-Specific: Food Web Structure

16 Site Specificity: Trophic structure Hudson River: Mixed sediment and water column sources Green Bay: Primarily water column source Predatory Fish (Largemouth Bass) Forage Fish #1 (Pumpkinseed) Forage Fish #2 (Brown Bullhead) Phytophilous macroinvertebrates (PMI) Surface sediment deposit feeding invertebrates (BMI) Periphyton Surface sediments PCBs associated with organic carbon Water column Dissolved PCBs

17 Site Specificity: Sediment/Water Relationship Relationship between water and sediment controls BAF and BSAF Varies within a water body

18 Site Specificity: Sediment/Water Ratio Sediment/water ratio Total PCBs in a small stream Even on this scale, there is significant variation in the ratio of sediment/water Water Surface Sediments

19 Accounting for Site Specificity With Modeling AIR WATER Hydrodynamics Hydrology Hydrodynamics Sediment Transport Suspended Solids Physical/ Chemical Volatilization Dissolved Organic Carbon Partitioning Dissolved Component Partitioning Particulate Component Invertebrates Food Chain Bioaccumulation Forage Fish Predatory Fish Interfacial Bed Layer Settling Scour Diffusion Predation Surface Sediment Mixing BED Intermediate Layer Burial to Deep Bed Groundwater Advection PartitioningDOC PART DIS Benthic Invertebrates Deep Bed Diffusion to Deep Bed

20 Food Web Model Mechanistic description of the primary energy transfer pathways from exposure sources to species of interest dv dt i = K u i c + α c n j = 1 C ij v j ( K i + G ) v i i uptake from water uptake from food loss due to elimination and growth dilution

21 Model Analysis Hudson River Example Sediments Fish

22 Measuring a BAF or BSAF in the Field Recent presentation of issues and methods Burkhard, ET&C 22(2): Arnot and Gobas Env. Rev. 14: Field protocols for BAF, BSAF are not available

23 Measuring a BAF or BSAF in the Field Weight of evidence recommended Balance uncertainty and data preference hierarchy EPA prefers field-based BAFs, BSAFs Evidence may include: Site-specific and chemical-specific biota, water and sediment data Chemical-specific information (K OW, metabolism) Site-specific data for related chemicals Chemical-specific data from other sites

24 Measuring a BAF or BSAF in the Field Study design depends on factors that include: Chemical properties (K OW, metabolism) Food web structure Sediment/water concentration ratio Seasonality (migration, reproduction, lipid content) Spatial variation Avoiding local elevated sediment or water concentrations to estimate a system-wide average Home range Temporal variation in exposure concentrations (seasonal variation due to fate and transport processes)

25 Linking Water Quality Standards and Fish Advisories GLI water quality criteria for PCBs to protect wildlife = 120 pg/l Human health example from Georgia - Relevant Risk-Based Water Quality Standards for PCBs: 64 pg/l (USEPA guidance) 97 pg/l (Alabama WQS) 170 pg/l (Georgia WQS) Are water quality standards achievable and necessary for reaching risk-based goals?

26 High-Volume Sampling of Surface Waters In Locations With No Advisory 6 sites, 2 each in 3 river basins in Georgia Savannah River Oconee River Ocmulgee River Sampled June 2005 Infiltrex high-volume trace organics sampler (Axys Environmental) Target sample volumes of 1000 L Analysis by EPA Method 1668, Revision A ( 1668A )

27 Fish Tissue & Surface Water PCBs Savannah Oconee Ocmulgee

28 PCB Concentrations in Surface Waters Check GLI PCBs in Georgia Surface Waters Total PCB Concentration (pg/l) Lake Russell Savannah R. Lock and Dam Lake Oconee Lake Sinclair Hawkinsville Hwy 280 Georgia WQS GLI wildlife EPA HH Guidanc Savannah River Oconee River Ocmulgee River WQS exceeded in areas with no local PCB sources. Also, where there is no advisory: It is not necessary to achieve the WQS to meet fish consumption goals

29 High-Volume Sampling in Precipitation Coosa River Basin, Georgia Four Sampling Events: Spring, Summer, Fall 2004 Winter 2005 Volumes of 8 to 40 L Collected Analysis by Method 1668A

30 Precipitation Sampling Locations

31 PCBs in Precipitation Total PCB Concentration (pg/l) , Spring 2004 Summer 2004 Fall 2004 Winter 2005 Georgia WQS GLI wildlife EPA Guidance Values corrected for blank contamination as well as for small sample masses Precipitation samples exceed WQS and guidance: The water quality standards are not achievable

32 Consistency and Conservatism: Human Health Example Human health water quality criteria for PCBs use the BCF GLI uses the BAF (about 1,000,000 L/kg). This is the correct method. Using the BAF, human health WQC become 2 to 6 pg/l This is unmeasurable even with method 1668 It is more one to two orders of magnitude below background EPA EPA AL GA EPA GA GA WQC WQC WQC WQC Fish Adv'y Fish Adv'y Fish Adv'y GLI interim Weiss Lake Coosa River Rec'd value TMDL TMDL Guidance cancer cancer cancer cancer noncancer cancer noncancer Risk level 1.E-05 1.E-06 1.E-05 1.E-06 1.E-04 Cancer Slope Factor (mg/kg-day) Dose mg/kg-day 5.0E E E E E E E-05 Body weight kg Averaging time years Exposure duration years Fish Consumption Rate kg/day Fish Concentration mg/kg BCF/BAF L/kg wet weight 901,954 31,200 31,200 31,200 Water Quality Criterion pg/l

33 Mercury Mercury bioaccumulation is in general more complicated than PCB bioaccumulation Criteria in terms of total mercury (thg) Methyl mercury (mhg) is of primary concern to higher trophic levels Relationship of mhg to thg is variable Balance between methylation and demethylation, both bacterial activities Methylation controlled by: Inorganic mercury, organic carbon and sulfide concentrations Sulfate reduction rate

34 Methyl Mercury Bioaccumulation at the Base of the Food Web CRUSTACEANS ZOOPLANKTON MeHg (mg/kg) SEDIMENT (mg/kg OC) SEDIMENT (mg/kg OC) Data source: Lavaca Bay, TX

35 Proportion mhg in Sediments Is Site-Specific More S = less neutral Hg-S = complexes less bioavailable Hg 2+ More inorganic Hg2+ more methylation Benoit et al EST 33:951 King et al ETC 18:1362

36 Proportion mhg Varies With Trophic Level 1.2 methyl:total mercury SEDIMENT MOLLUSKS AMPHIPODS FORAGE FISH POLYCHAETES ZOOPLANKTON CRUSTACEANS PREDATOR FISH Data source: Lavaca Bay, TX

37 Total Mercury Site-Specificity of Bioaccumulation in Fish Mercury levels in fish do not bear a simple relationship to exposure sources Mercury in Mummichogs Mercury in Mummichogs Tissue (ppm) BSAF Sediment (ppm) Sediment (ppm) Weis et al Can. J. Fish. Aquat. Sci. 58: Brain Liver 1 to 1 BSAF (brain) Weis et al Can. J. Fish. Aquat. Sci. 58: BSAF (liver)

38 Conclusions Methodologies are available to estimate the linkage between tissues and water and sediment Key issues Consistency between regulatory endpoints Achieving water quality criteria should be both necessary and sufficient to achieve risk-based goals. Achievability of water quality criteria Site-specificity of the linkage between wildlife tissues and water Food web structure, sediment/water relationship Additionally, for mercury: methylation dynamics