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Appendix C:
Bioavailability Tools and Methods

Appendix C-T1. Direct pore-water sampling devices
Appendix C-T2. Indirect pore-water sampling devices
Appendix C-T3. Freshwater sediment toxicity testing and pore-water and elutriate tests
Appendix C-T4. Modeling
Appendix C-T5. Tissue sampling and analysis
Appendix C-T6. Select methods for sampling benthic invertebrate communities
Appendix C-T7. Surface-water quality models (fate and transport)
Appendix C-T8. Fish uptake calculation methods and models
Appendix C-T9. Wildlife calculation methods and models and direct measures

 

Appendix C-T1. Direct pore-water sampling devices Print this table

Method: Centrifugation
Description: Collection of sediment followed by centrifugation. Filtration and/or flocculation of residuals are possibly necessary.

Measured endpoints: Analysis of pore-water chemistry and comparison with ambient water quality criteria. If sufficient volume is collected, aquatic toxicity tests may be conducted using standard methods (e.g., Daphnia acute toxicity testing).

References: USEPA 2001b, NFESC 2003
Advantages: Relatively inexpensive and can be done at most commercial labs. Conservative but generally accepted method by regulatory agencies.

Disadvantages: Requires large volumes of sediment and ability to centrifuge large samples at ~10,000 g or higher. Limited sample volumes generated, especially for some sediment types. Can alter pore-water chemistry (i.e., redox).
Analyte capability: All analytes depending on sample volume
Method: Suction devices
Description: A syringe, airstone, or tubes of varying length (e.g., Michigan sampler) with one or more sampling ports inserted into the sediment to the desired depth. Suction is applied via various means to directly retrieve the pore water sample.

Measured endpoints: Analysis of pore-water chemistry and comparison with ambient surface-water quality criteria. If sufficient volume is collected, aquatic toxicity tests may be conducted using standard methods (e.g., Daphnia acute toxicity testing).

References: ASTM E1391 2008; USEPA 2001b, n.d. “Measurement”
Advantages: Relatively inexpensive and can be done in situ or within most commercial labs. Conservative but generally accepted method by regulatory agencies.

Disadvantages: In situ, low-flow rates in fine-grained substrates. Also need to prevent short-circuiting of overlying surface water. In the laboratory, large volumes of sediment are required (10:1). Limited sample volumes generated especially for some sediment types. Can alter pore-water chemistry (i.e., redox).
Analyte capability: All analytes depending on sample volume
Method: Piezometers (field)
Description: Similar to laboratory suction devices, suction is applied via various means (usually a peristaltic pump) to directly retrieve the pore-water sample from a piezometer in the field.

Measured endpoints: Pore-water concentrations. Concentration limit is method specific.

References: USEPA n.d. “Measurement”
Advantages: Relatively easy to install and extract pore water. Can repeatedly sample from same location using dedicated tubing.

Disadvantages: Can alter pore-water chemistry (i.e., redox). Need to ensure that overlying surface water is not being drawn. Sample volume dependent on achievable flow rate.
Analyte capability: All analytes depending on sample volume
Method: Trident probe (U.S. Navy)
Description: Direct-push probe that also collects depth, temperature, and conductivity to determine the appropriate depth for pore-water sampling.

Measured endpoints: Analysis of pore-water chemistry and comparison with ambient surface-water quality criteria. If sufficient volume is collected, toxicity testing may also be conducted using pore-water/surface-water methods (e.g., Daphnia acute toxicity testing).

References: USEPA n.d. “Measurement,” Chadwick and Hawkins 2008
Advantages: Can determine groundwater/ surface-water interface through changes in conductivity and temperature.

Disadvantage: Limited familiarity and availability among commercial laboratories.
Analyte capability: Metals all analytes depending on sample volume
Method: Solid-phase microextraction—USEPA SW-846 Method 8272, ASTM D7363-07
Description: Direct analysis of hydrophobic organics in sediment pore water. Small sediment sample (40 mL) centrifuged and dissolved solids flocculated in the laboratory. SPME fiber added to supernatant and then injected into GC. ASTM method same as SW‑8272 except the analysis of alkylated PAHs is specified.

Measured endpoints: Pore water at low concentrations (pg/mL).

References: USEPA SW-846 Method 8272, Hawthorne et al. 2007
Advantages: Small sediment volume (40 mL) and low detection limits (pg/mL). Procedure does not involve revisiting the site. Removes the limitations imposed by using EqP. Large database relating aquatic toxicity to pore-water concentrations for comparison with site samples.

Disadvantages: Fairly complex analytical and data interpretation technique. Method SW-8287 specifies the analysis of only 16 priority pollutants PAH compounds (not alkylated compounds).
Analyte capability: PAHs, PCBs, pesticides
Method: Air bridge
Description: Works on the principle that organic compounds dissociate from sediments into water, diffuse into air, and then redissolve into clean water as freely dissolved compounds. Measures “truly dissolved” chemical constituents in water.

References: Fernandez et al. 2009
Advantages: Method assesses freely dissolved hydrophobic concentrations of compounds such as PAHs and PCBs.

Disadvantages: Slow process; larger molecular weight compounds may take weeks, if not months, to equilibrate.
Analyte capability: PAHs, PCBs, pesticides, energetic compounds (nonpolar organics

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Appendix CT-2. Indirect pore-water sampling devices Print this table

Method: Diffusion equilibration on thin films

Description: Thin (<1 mm) film of gel over a rigid support attains equilibrium with pore water. Measures metal concentrations in pore water, and the concentration limit is method specific.

References: USEPA n.d. “Measurement”

Advantage: More rapid equilibrium than with peepers.

Disadvantage: Need to extract sorbed compounds from the gel for analysis.
Analyte capability: Metals, mercury
Method: Dialysis bags
Description: Contaminant diffuses into permeable dialysis material (polyvinylidene fluoride, polycarbonate) filled with water. Measures pore-water concentrations. Concentration limit is method specific.

References: USEPA 2001b, n.d. “Measurement”
Advantages: Easy to install and extract pore water.

Disadvantages: Requires modification to water within the bag for different sediment conditions.
Analyte capability: Metals, mercury, nonpolar organics
Method: Sediment peeper
Description: Contaminant diffuses across a permeable membrane surrounding a fixed support filled with water. Measures pore-water concentrations. Concentration limit is method specific.

References: ITRC 2004; USEPA 2006b, n.d. “Measurement,” 2001b
Advantages: Easy to install and extract pore water. Vertical distribution of contaminants with depth.

Disadvantages: Requires modification to water within the bag for different sediment conditions. Low volume of pore water extracted.
Analyte capability: Metals, mercury, VOCs, PAHs, PCBs, pesticides, radionuclides, energetic compounds (nonpolar organics)
Method: Diffusion gradients in thin films (DGT)
Description: Binding agent is selective to target ions in solution immobilized in a thin layer of hyrogel, surrounded by an ion-permeable hydrogel layer. Collects metal ions by diffusion, and measures/estimates contaminant flux in pore water.

References: USEPA n.d. “Measurement”
Advantages: Rapid determination of flux (linear concentration gradient) in sediments.

Disadvantages: Does not measure equilibrium pore-water concentration.
Analyte capability: Metals, mercury
Method: Semipermeable-membrane devices
Description: Diffusion of hydrophobic contaminants across a semipermeable bag into a purified oil (e.g., triolein) which serves as a surrogate lipid. Integrates pore-water concentrations by averaging over a specified deployment period. Though not an equilibrium sampler, compound-specific flux rates are available.

References: USEPA n.d. “Measurement”
Advantages: Relatively easy to deploy. Reverse extraction of dialysis tubing conducted by vendor. Measures “truly dissolved” pore-water constituents. Low (pg/L) concentration limits.

Disadvantages: Does not measure pore-water concentration but rather an average concentration over time.
Analyte capability: PAHs, PCBs, nonpolar pesticides
Method: SPME fibers
Description: SPME fibers are disposable glass fibers coated with µm poly(dimethylsiloxane). Fibers are cleaned by sonicating sequentially with hexane, acetonitrile, and water and are inserted directly into sediment in 5–7 cm lengths. Fibers are withdrawn after a set number of days, cut into small pieces, and transferred to autosampling vials, which are then filled with hexane and analyzed on a GC/MS. Measures pore water at low concentrations.

References: Adams et al. 2007
Advantages: In situ or in vitro methods which determine pore-water concentrations and/or can be correlated with bioaccumulation. Low (<pg/mL) detection limits.

Disadvantages: In situ procedures require site revisits. Methods require equilibrium time with sediments (14–28+ days), and also require method- and compound-specific EqP coefficients.
Analyte capability: PAHs, PCBs, nonpolar pesticides
Method: Polyoxymethylene (POM) film
Description: Sorption onto polymer surface with pore-water concentration determined through compound-specific partition coefficients. Various in situ or in vitro methods are being developed and tested to indirectly measure pore-water concentrations and bioavailable fractions.

References: Adams et al. 2007, Ghosh and Hawthorne 2010

Advantages: In situ or in vitro methods which determine pore-water concentrations and can be correlated with bioavailability. Low (<pg/mL) detection limits.

Disadvantages: In situ procedures require site revisits. Methods require equilibrium time with sediments (14–28+ days) and also require method- and compound-specific EqP coefficients.

Analyte capability: PAHs, PCBs, pesticides, energetic compounds (nonpolar organics)
Method: Polyethylene devices
Description: Passively accumulate hydrophobic organic compounds in proportion to their freely dissolved concentrations; require equilibrium with the sampled medium. Samples are time-weighted. Measures pore water at low (<pg/L) concentrations.

References: Adams et al. 2007, Ghosh and Hawthorne 2010, Gschwend 2010
Advantages: In situ or in vitro methods which determine pore-water concentrations and can be correlated with bioavailability. Low (<pg/L) detection limits.

Disadvantages: In situ procedures require site revisits. Methods require equilibrium time with sediments (14–28+ days) and also require method- and compound-specific EqP coefficients.
Analyte capability: PAHs, PCBs, nonpolar pesticides, energetic compounds (nonpolar organics)
Method: GORE® Modules
Description: The GORE Module, a sorbent-based diffusion groundwater sampler, is a waterproof, vapor-permeable GORE-TEX® membrane within a deployment device. The membrane serves as the interface between an aqueous setting (groundwater) and the sorbent housed within the membrane tube. It measures groundwater concentrations (ppb). It has not been validated as a pore-water sampling device.

References: ITRC 2007, USEPA 2000b
Advantages: Rapid equilibrium (hours), inexpensive, and easy to install.

Disadvantages: Does not sorb higher-molecular-weight compounds; not useful for calculating TUs if higher-molecular-weight compounds are present. Has not been verified as an acceptable pore-water sampling device.
Analyte capability: VOCs

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Appendix C-T3. Freshwater sediment toxicity testing
and pore-water and elutriate tests
Print this table

Tool/test species
Method
Duration
Measurement endpoints
Selected bedded-sediment freshwater toxicity tests
Acute tests
Hyalella azteca (amphipod) ASTM 2005, 2008; USEPA 2000c 10–14 day Survival
Chironomus spp. (midge) ASTM 2005, 2008; USEPA 2000c 10 day Survival, growth
Lumbriculus variegatus (oligochaete) ASTM 2007b, USEPA 2000c 10 day Survival
Hexagenia limbata (mayfly larvae) ASTM 2005, 2008 10 day Survival
Chronic tests
Hyalella azteca (amphipod)< ASTM 2005, 2008; USEPA 2000c 28–42 day Survival, growth, reproduction
Chironomus spp. (midge) ASTM 2005, 2008; USEPA 2000c 20 day Survival, growth
Chironomus spp. (midge) ASTM 2005, 2008; USEPA 2000c 30 day Life cycle
Hexagenia spp. (mayfly) ASTM 2007b, USEPA 2000c 21 day< Survival, growth
Tubifex tubifex (tubificid oligochaete) ASTM 2007b 28 day Survival, growth, reproduction
Rana pipiens (frog) ASTM 2007a 28 day Survival, growth, reproduction
Xenopus (frog) ASTM 2007a 28 day Survival, growth, reproduction
Amphibian larvae NAVFAC 2004 10 day Survival, growth, reproduction
Bioaccumulation tests
Diporeia spp. (amphipod) ASTM 2007a 28 day Survival, bioaccumulation
Lumbriculus variegatus (oligochaete) ASTM 2007a, USEPA 2000d 28 day Bioaccumulation
Selected freshwater pore-water and elutriate toxicity tests
Daphnia magna Pore water–ASTM 2001a 48 hour Survival
Ceriodaphnia dubia Pore water–ASTM 2001c 7 day Survival, reproduction
Pimephales promelas (fathead minnow) Pore water–ASTM 2001b 7 day Survival, growth
Selenastrum capricorntum (algae) >Elutriate–Weber et al. 1989 96 hour Survival, reproduction
Ceriodaphnia dubia Elutriate–Weber et al. 1989 7 day Survival, growth
Pimephales promelas (fathead minnow) Elutriate–Weber et al. 1989 7 day Survival, growth
Salmo spp.(salmonid) Elutriate–Weber et al. 1989 96 hour  
Selected bedded-sediment marine toxicity tests
Acute tests
Ampelisca abdita (amphipod> >ASTM 2007b, 2008; USEPA 1994c 10 day Survival
Eohaustorius estuarius (amphipod) ASTM 2007b, 2008 10 day Survival
Rhepoxynius abronius (amphipod) ASTM 2007b, 2008; USEPA 1994c 10 day Survival, reburial
Grandidierella japonica (amphipod) ASTM 2007b, 2008 10 day Survival
Leptocheirus plumulosus (amphipod) <>ASTM 2007b, 2008; USEPA 2001b 10 day Survival
Corophium spp. (amphipod) ASTM 2007b, 2008 10 day Survival
Neanthes arenaceodentata (polychaete) ASTM 2007b, 2008 10 day> Survival
Chronic tests

Neanthes arenaceodentata

ASTM 2007b

28 day

Survival, growth

Armandia brevis   28 day Survival, growth
Leptocheirus plumulosus (amphipod) ASTM 2008, USEPA 2001b 28 day Survival, growth, reproduction
Bivalve larvae (oyster, larvae)   48 hour Larval development
Echinoderm (sea urchin, sand dollar)      
Bioaccumulation tests
Macoma spp. (clam) USEPA 1998b 28 day Survival, bioaccumulation
Neanthes (Nereis) spp. (polychaete) ASTM 2007a, 2007b 28 day Bioaccumulation

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Appendix CT-4. Modeling Print this table

Method: Equilibrium partitioning (EQP)
Description: Assumes pore-water concentration equivalent to NRWQC FCV, then back-calculates a bulk sediment concentration (or OC-normalized sediment concentration) using a Koc (or Koc calculated from a Kow) of the COC of interest (dissolved phase = OC-normalized total sediment concentration * partitioning coefficient).

References: Di Toro et al. 1991, 2005a; Di Toro 2008; Hansen et al. 1996; USEPA 1994a, 2003d
Advantages: Easy to calculate. Is a low-cost screening tool.

Disadvantages: Assumptions do not take into account the presence of anthropogenic carbon or other factors which may influence default partitioning coefficients.
Analyte capability: PAH, PCB, nonpolar pesticides, energetic compounds (nonpolar organics)
Method: Narcosis model
Description: Predicts toxic effects to benthic organisms from impacted sediments using a universal model that predicts toxicity based on a critical body burden that assumes the lipid compartment is the toxic target for Type I narcotic (hydrophobic) chemicals.

References: USEPA 2003d, 2008b; Di Toro, McGrath, and Hansen 2000; Di Toro and McGrath 2000
Advantages: Model is validated across 156 chemicals and 33 aquatic species. TUs are assumed to be additive. Forms the basis of applying EqP to predict sediment toxicity assuming pore water is equivalent to final acute values (as the NOAEL endpoint). Is a low-cost screening tool.

Disadvantages: Assumes that sediment toxicity is entirely the result of narcotic effects to benthic organisms when in reality other stressors may be contributing to adverse impacts.
Analyte capability: Type I narcotic chemicals (aliphatics, aromatics, alcohols, ethers, ketones, PAHs)
Method: Biotic ligand model
Description: Variation of the free metal ion activity model that accounts for varying bioavailability of metals as a function of varying water chemistry.

References: Di Toro et al. 2005b
Advantages: Accounts for toxicity variations due to changes in alkalinity, pH, and OC.

Disadvantages: None reported or identified.
Analyte capability: Metals, mercury
Method: Simultaneously extracted metal/acid volatile sulfide (SEM/AVS)
Description: Amorphous iron sulfide is measured as AVS; the metal in sediments that is potentially bioavailable is measured in the same extract and is termed “simultaneously extracted metals” (SEM). If AVS > SEM, then no toxicity is expected. If SEM > AVS, then toxicity may or may not occur.

References: USEPA 2005c, Di Toro et al. 1990, Di Toro 2008, Hansen et al. 1996
Advantages: Easy to conduct; methods widely available from certified labs. Low-cost screening tool.

Disadvantages: Recommended that field samples be taken as cores to avoid contact with air (which may oxidized reduced sulfides). Recent round robin of certified laboratories showed considerable variability in results.
Analyte capability: Divalent metals (Cd, Cu, Pb, Ni, Ag, Zn)
Method: Toxicity identification evaluation (TIE)
Description: Series of aquatic toxicity laboratory tests that manipulate physical/chemical properties of sediment pore water to bind classes of chemicals and certain confounding factors, thus rendering them biologically unavailable.

References: USEPA 2007b, NFESC 2003
Advantages: Can assist in identifying site-related COCs and/or confounding factors contributing to observed toxicity.

Disadvantages: A precursor to the TIE test is a toxicity test—expensive and time-consuming. Does not address bioaccumulation issues. Small number of amendments to be cost-effective.
Analyte capability: Metals, VOCs, PAHs, PCBs, pesticides, radionuclides, energetic compounds (nonpolar organics)

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Appendix C-T5. Tissue sampling and analysis Print this table

Method: Biota-sediment accumulation factor (BSAF)
Ctss/L = (Cs/TOC) * BSAF
where
Ctss = tissue concentration at steady state (mg/kg)
L = lipid content (g/g)
Cs = sediment concentration (mg/kg)
TOC = total organic carbon in sediment (g/g)
BSAF = biota-sediment accumulation factor (g carbon/g lipid)

Links: www.epa.gov/med/Prods_Pubs/bsaf.htm, http://el.erdc.usace.army.mil/bsafnew/BSAF.html
Advantages: Simple estimation tool that can use default USEPA values or develop site-specific factors based on measured tissue and sediment concentrations. Simple and easily performed using spreadsheet functions data set of BSAFs for nonionic organic chemicals exist from USEPA and the USACE.

Disadvantages: BSAFs derived from literature sources do not reflect site-specific conditions. Site-derived BSAFs implicitly assume that all exposures occur within the area under investigation.
Analyte capability: PAHs, PCBs, nonpolar pesticides, dioxins, energetic compounds (nonpolar organics)

Applicable compound class: Hydrophobic (nonionic) organics (PCBs, PCDDs, PCDFs, DDTs, PAHs, chlorinated pesticides)
Method: Bioaccumulation factor (BAF)
Description: Ratio of the concentration in aquatic organism to its concentration in specific media (water, sediment, prey). Bioaccumulation is net uptake and retention of a chemical in an organism from all routes of exposure (diet, dermal, respiratory) and any source (water, sediment, food) in the natural environment.

References: USEPA n.d. “ECOTOX,” Weisbrod et al. 2007
Advantages: Simple estimation tool that can use default USEPA values or develop site-specific factors based on measured tissue and other site media concentrations. Can be used for all aquatic and aquatic-dependent wildlife.

Disadvantages: BAFs derived from literature sources do not reflect site-specific conditions. Site-derived BAFs implicitly assume that all exposures occur within the area under investigation.
Analyte capability: PAHs, PCBs, nonpolar pesticides, dioxins, energetic compounds (nonpolar organics)

Applicable compound class: Hydrophobic (nonionic) organics (PCBs, PCDDs, PCDFs, DDTs, PAHs, chlorinated pesticides)
Method: Biomagnification factor in predator/prey tissue
Description: Ratio of the chemical concentration of a predator divided by that of its prey. For HOCs, the concentrations are lipid normalized. For metals, the units are mg/kg wet weight. Biomagnification is said to occur when the BMF > 1.

References: USEPA n.d. “ECOTOX,” Weisbrod et al. 2007, USACE n.d., USEPA 1993
Advantages: Simple tool that may be used to estimate concentrations in higher trophic level fish, birds or mammals based on measured or previously reported BMFs.
Can be used for all aquatic and aquatic-dependent wildlife.

Disadvantages: BMFs derived from literature sources may not reflect site-specific conditions. Site-derived BMFs implicitly assume that all exposures occur within the area under investigation.
Analyte capability: Metals, mercury, VOCs, PAHs, PCPs, pesticides, selenium, dioxins, radionuclides, energetic compounds (nonpolar organics)
Method: Gobas kinetic food web model
Description: Widely applied food web model that provides estimates of chemical concentrations in organisms of aquatic food webs from chemical concentrations in the water and the sediment.

Measured endpoints: A prediction of specific body burdens of organic COCs at specified trophic levels and at specified growth stages. Model allows user-specified aquatic food web that can include benthos, phytoplankton, and zooplankton. Recent work by Burkhart, Cook, and Lukasewycz (2005) suggests that model predictions are within a factor of 4 of simple BSAF predictions.

References: Arnot and Gobas 2004; Gobas 1993; Burkhart, Cook, and Lukasewycz 2005
Advantages: Variations of the algorithm have been adapted to both freshwater and marine systems, including the Great Lakes, Lower Fox River, Wisc., San Francisco Bay, Calif., and Willamette River, Ore. Relatively easy for those areas where model has been calibrated and validated (e.g., San Francisco Bay). Increasingly difficult for new systems. Model currently provides point estimates. A better method for quantifying uncertainty (e.g., Monte Carlo simulations) remains to be adequately demonstrated.

Disadvantages: Data-intensive to populate and calibrate the model. Steep learning curve if not well-versed in fugacity theory.
Analyte capability: Metals, PAHs, PCPs, nonpolar pesticides, PCBs, dioxins, energetic compounds (nonpolar organics)
Method: Bioaccumulation and Aquatic System Simulator (BASS)
Description: Model simulates bioaccumulation of chemical pollutants integrated with population and bioaccumulation dynamics of age-structured fish communities. Provides a prediction of specific body burdens of organic COCs at specified trophic levels and at specified growth stages. Model allows user-specified aquatic food web that can include benthos, phytoplankton, zooplankton, and multiple trophic levels of fish.

References: USEPA 2008b, Barber 2008
Advantages: Applied to PCB dynamics in Lake Ontario; salmonids, largemouth bass-bluegill-catfish communities of Lake Hartwell, S.C.; DDT bioaccumulation in caged channel catfish at various Superfund sites; and to simulate fish methylmercury bioaccumulation in the Florida Everglades.

Disadvantages: Data-intensive to populate and calibrate the model.
Analyte capability: Hydrophobic organic pollutants and metals that complex with sulfhydryl groups (e.g., Cd, Cu, Hg, Ni, Ag, Zn)
Method: Food web model for environmental risk assessment for mercury (SERAFM)
Description: SERAFM is a steady-state spreadsheet-based model framework that predicts speciated mercury concentrations (Hg0, HgII, MeHg, total Hg) in freshwater and sediments and total mercury concentrations in fish tissue. It includes the following measurement endpoints:

  • bulk sediment Hg concentration
  • fish tissue Hg
  • total and dissolved Hg in surface water
  • TOC and DOC in sediment and water
  • water-column particle size
  • water temperature, DO, pH

Test organism categories: Freshwater omnivore and piscivorous fish at user-specified age classes.

References:
USEPA n.d. “SERAFM,” Knightes 2008

Advantages: USEPA model that has general acceptance to predict the fate of mercury in aquatic systems and hazard indices for wildlife.

Disadvantages: Does not consider controlling factors of methylmercury bioavailability in sediments. Requires assumption that sediments are source of Hg.
Analyte capability: Mercury
Method: Direct plasma residue assessment
Description: Plasma from receptor organisms are collected from the field, brought to the laboratory, and measured for target chemical(s).

Measured endpoints include plasma COCs and percent lipids. Principally used to test organisms to assess chemical levels in T&E species and/or juveniles.

References: Arcand-Hoy and Bensen 1998
Advantages: Integrates all pathways of exposure and provides a direct number for assessing risks without killing receptor.

Disadvantages: Sampling generally limited to few individuals. Resource-intensive. Plasma COCs not associated with specific toxicological effects.
Analyte capability: All classes of chemicals
Method: Direct tissue analysis
Description: Receptor organisms are harvested from the field and brought to the laboratory, and tissues are measured for target chemical(s).

Measured endpoints include the following:

  • bulk sediment COCs concentrations
  • tissue residue COCs
  • total and dissolved COCs in surface water
  • whole body vs. fillet (fish)
  • TOC and DOC in sediment and water
  • water-column particle size
  • fertilized eggs (optional)
  • lipids

Test organism categories include fish, shellfish, amphibians, or reptiles.

References: Puget Sound Partnership 1990, USEPA 2000c

Advantages: Integrates all pathways of exposure and provides a direct number for assessing risks.

Disadvantages: Assumptions include all exposures are within contaminated area, which is not valid for mobile fish or crustaceans. Not suitable for T&E species. Moderate to difficult to implement. Requires capture (trawling, reel, beach seine) of suitable numbers and types of target receptors for evaluation in statistically meaningful way.
Analyte capability: All classes of chemicals
Method: In situ bioaccumulation studies
Description: Surrogate receptor organisms are placed at the target site in cages either in contact with or directly above the sediment. After a specified period of time, the organisms are harvested and the tissues analyzed for COCs. The measurements include survival, tissue residue, and lipids.

Test organisms include benthic organisms, small fish, clams, and mussels.

References: USEPA 2000a
Advantages: Animals confined to a small, well-defined location. Site-specific exposures that integrate contaminant uptake over all media.

Disadvantages: Surrogate organisms are often those used in bioassays and may not reflect uptake by site-specific organisms.
Analytical capability: Most classes of chemicals but typically PBT compounds
Method: Dietary assimilation efficiency
Description: Absorption efficiency represents the net result of absorption and elimination. Feeding studies are designed to estimate absorption efficiency based on accumulated chemical residues. The fraction of the chemical retained in the organisms relative to that ingested is the assimilation efficiency, which measures chemical levels in food and residual in feces. Also may involve measuring chemical levels in target organism tissue, organelles, and in developing fetus.

Test organisms are typically fish, birds, and mammals.

References: Erickson et al. 2008
Advantages: Most direct measure of how much of a contaminant in food is retained by the target organism.

Disadvantages: Difficult to adequately capture fish fecal matter. Useful for birds and mammals but can be time- and resource-intensive.
 

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Appendix CT-6. Selected methods for sampling
benthic invertebrate communities
Print this table

Method: Passive artificial substrates
Description: Artificial substrate samplers are designed to mimic natural substrates (e.g., gravel, cobble, small spaces) and provide an easily quantified sampling unit. In general, artificial substrate samplers primarily sample the epifaunal community, whereas grab samplers primarily sample the infaunal community. Artificial substrate samplers can provide both qualitative and quantitative samples of benthic macroinvertebrates. Ohio Environmental Protection Agency recommends using of Hester-Dendy artificial substrate samplers in streams and rivers, five samplers exposed for six weeks.

Measured endpoints: EPT richness and diversity at family and genus level of taxonomic resolution.

References: OEPA 1989, Johnson 2006, USEPA 2002d
Advantages: Mesh artificial substrate samplers are a good alternative to grab samplers when collecting animals for tissue residue analyses. Artificial substrate samplers made of mesh-filled chicken baskets are particularly good at collecting large numbers of animals because of the large number of interstitial spaces.

Disadvantages: None reported.
Analyte capability: Epifaunal populations
Method: Benthic response index (BRI)
Description: The BRI is the abundance-weighted average tolerance score of organisms occurring in a sample.

Measured endpoints:
Southern California Marine Bays:
    Reference: <39.96
    Low disturbance: 39.96–49.14
    Moderate disturbance: 49.15–73.26
    High disturbance: >73.26

Polyhaline Central San Francisco Bay:
    Reference: <22.28
    Low disturbance: 22.28–33.37
    Moderate disturbance: 33.38–82.08
    High disturbance: >82.08

References: Smith et al. 2003; California EPA 2008, 2009
Advantages: Indices remove much of the subjectivity associated with data interpretation. Indices provide a simple means of communicating complex information to managers, tracking trends over time, and correlating benthic responses with stressor data.

Disadvantages: Requires development and calibration. Different benthic indices have been used at different times and different places, and results cannot be compared across regions because the various indices have not yet been rigorously compared and intercalibrated. Initial development of each existing benthic index was constrained by data limitations, and they would all benefit from refinement with additional data as well as independent validation. Differences in sampling procedures. Habitat factors such as seasonality and sediment type. Accuracy of identification of benthic organisms of performance of California benthic indices. Indices only one line of evidence in determining causality of impairment. Indices often used in conjunction with multiple lines of evidence.
Analyte capability: Species specific
Method: Index of benthic biotic integrity (IBI

Description: The IBI identifies community measures that have values outside a reference range.

Measured endpoints:
Southern California Marine Bays:
    Reference: 0
    Low disturbance: 1
    Moderate disturbance: 2
    High disturbance: 3 or 4

Polyhaline Central San Francisco Bay:
    Reference: 0 or 1
    Low disturbance: 2
     Moderate disturbance: 3
    High disturbance: 4

References: California EPA 2008, 2009

Advantages: Indices remove much of the subjectivity associated with data interpretation. Indices provide a simple means of communicating complex information to managers, tracking trends over time, and correlating benthic responses with stressor data.

Disadvantages: Requires development and calibration. Different benthic indices have been used at different times and different places, and results cannot be compared across regions because the various indices have not yet been rigorously compared and intercalibrated. Initial development of each existing benthic index was constrained by data limitations, and they would all benefit from refinement with additional data as well as independent validation. Differences in sampling procedures. Habitat factors such as seasonality and sediment type not taken into account. Accuracy of identification of benthic organisms of performance of California benthic indices. Indices only one line of evidence in determining causality of impairment. Indices often used in conjunction with multiple lines of evidence.
Analyte capability: Species specific
Method: Relative benthic index (RBI)
Description: The RBI is the weighted sum of (1) several community parameters (total number of species, number of crustacean species, number of crustacean individuals, and number of mollusk species) and abundances of (2) three positive and (3) two negative indicator species.

Measured endpoints:
Southern California Marine Bays:
    Reference: >0.27
    Low disturbance: 0.17–0.27
    Moderate disturbance: 0.09–0.16
    High disturbance: <0.09

Polyhaline Central San Francisco Bay:
Reference: >0.43
Low disturbance: 0.30–0.43
Moderate disturbance: 0.20–0.29
High disturbance: <0.20

References: California EPA 2008, 2009

Advantages: Indices remove much of the subjectivity associated with data interpretation. Indices provide a simple means of communicating complex information to managers, tracking trends over time, and correlating benthic responses with stressor data.

Disadvantages: Requires development and calibration. Different benthic indices have been used at different times and different places, and results cannot be compared across regions because the various indices have not yet been rigorously compared and intercalibrated. Initial development of each existing benthic index was constrained by data limitations, and they would all benefit from refinement with additional data as well as independent validation. Differences in sampling procedures. Habitat factors such as seasonality and sediment type not taken into account. Accuracy of identification of benthic organisms of performance of California benthic indices. Indices only one line of evidence in determining causality of impairment. Indices often used in conjunction with multiple lines of evidence.
Analyte capability: Species specific
Method: River Invertebrate Prediction and Classification System (RIVPACS)
Description: The approach compares the assemblage at a site with an expected species composition determined by a multivariate predictive model that is based on species relationships to habitat gradients (originally developed for British freshwater streams and adapted for California’s bays and estuaries).

Measured endpoints:
Southern California Marine Bays:
    Reference: >0.90–<1.10
    Low disturbance: 0.75–0.90 or 1.10–1.25
    Moderate disturbance: 0.33–0.74 or >1.25
     High disturbance: <0.33

Polyhaline Central San Francisco Bay:
     Reference: >0.68–<1.32
     Low disturbance: 0.33–0.68 or 1.32–1.67
     Moderate disturbance: 0.16–0.32 or >1.67
     High disturbance: <0.16

References: Wright, Furse, and Armitage 1993; Van Sickle, Huff, and Hawkins 2006; California EPA 2008, 2009
Advantages: Indices remove much of the subjectivity associated with data interpretation. Indices provide a simple means of communicating complex information to managers, tracking trends over time, and correlating benthic responses with stressor data.

Disadvantages: Requires development and calibration. Different benthic indices have been used at different times and different places, and results cannot be compared across regions because the various indices have not yet been rigorously compared and intercalibrated. Initial development of each existing benthic index was constrained by data limitations, and they would all benefit from refinement with additional data as well as independent validation. Differences in sampling procedures. Habitat factors such as seasonality and sediment type not taken into account. Accuracy of identification of benthic organisms of performance of California benthic indices. Indices only one line of evidence in determining causality of impairment. Indices often used in conjunction with multiple lines of evidence.
Analyte capability: Species specific
Method: Integration of benthic community
Description: The median of all benthic index response categories shall determine the benthic line of evidence category. If the median falls between categories, it shall be rounded up to the next higher category.

Measured endpoints:
Reference: A community composition equivalent to a least affected or unaffected site.
Low disturbance: A community that shows some indication of stress but could be within measurement error of unaffected condition.
Moderate disturbance: Confident that the community shows evidence of physical, chemical, natural, or anthropogenic stress.
High disturbance: The magnitude of stress is high.

References: California EPA 2008, 2009
Advantages: Index performance was evaluated by comparing index assessments of 34 sites to the best professional judgment of nine benthic experts. None of the individual indices performed as well as the average expert in ranking sample condition or evaluating whether benthic assemblages exhibited evidence of disturbance. However, several index combinations outperformed the average expert. When results from both habitats were combined, two four-index combinations and a three-index combination performed best.

Disadvantages: Requires development and calibration. Different benthic indices have been used at different times and different places, and results cannot be compared across regions because the various indices have not yet been rigorously compared and intercalibrated. Initial development of each existing benthic index was constrained by data limitations, and they would all benefit from refinement with additional data as well as independent validation. Differences in sampling procedures. Habitat factors such as seasonality and sediment type not taken into account. Accuracy of identification of benthic organisms of performance of California benthic indices. Indices only one line of evidence in determining causality of impairment. Indices often used in conjunction with multiple lines of evidence.
Analyte capability: Species specific
Method: Rapid bioassessment protocol (RBP)
Description: Choice of qualitative and/or quantitative protocols (three tiers) for use in streams and rivers. Protocols used to determine whether a stream and associated habitat are supporting a designated aquatic life use, characterize the existence and severity of impairment, and identify the source of impairment.

Measured endpoints:
Macroinvertebrates: Taxa richness, family biotic index, ratio of scrapers, filtering collectors, ratio of EPT and chironomid abundances, % contribution of dominant family, EPT index.
Fish: IBI, species richness and composition metrics, trophic composition metrics, fish abundance and condition metrics.

References: Barbour et al. 1999
Advantages: Bioassessment provides indications of cumulative impacts of multiple stressors, not just water quality. Biological community condition reflects both short- and long-term effects, and directly evaluates the condition of the habitat and water resource. Biological data can be interpreted based on regional reference condition where single reference sites are lacking or inadequate. Properly developed methods, metrics, and reference conditions provide a tool that enables a direct measure of the ecological condition of a water body. Once a framework is in place for bioassessment, biological monitoring can be relatively inexpensive and easily performed with standard protocols and consistent training.

Disadvantages: May be difficult to interpret results in areas impacted by urban/nonpoint contamination or areas impacted by numerous site discharges. Additional chemical and biological (toxicity) testing is usually needed to identify causal agent.
Analyte capability:
Macro-invertebrate species
Method: Invertebrate community index (ICI)
Description: ICI is a summary measure of 10 metrics representing aquatic macroinvertebrate community integrity and is evaluated and scored in relation to conditions at relatively undisturbed reference sites In this index, a site can receive a 6, 4, 2, or 0 score depending on how it compares to the specified reference site.

Measured endpoints:
Total number of taxa—species richness and diversity

Number of mayfly taxa—pollution-sensitive species; greater proportion of taxa indicates higher environmental quality

Number of caddisfly taxa—main component in larger, unimpacted waterways; wide range of pollution tolerances within taxa

Number of Dipteran taxa—have wide range of tolerances to pollution; often only organism collected under heavily polluted conditions; greater proportion suggests lower stream quality

Percent mayfly composition—easily affected by even minor disturbances; serves as measure of overall levels of stress and disturbance

Percent caddisfly distribution—quickly absent under environmental stress; serves as a measure of stream stress

Percent tribe Tanytarsini midge composition—often predominant group at minimally impacted sites; pollution tolerances are intermediate

Percent other Dipteran and noninsect composition—includes noninsect invertebrates such as worms, isopods, snails, etc.; main community component in poor water-quality conditions; greater abundance indicates lower environmental quality

Percent tolerant organisms—tolerant to toxic and organic pollution; greater proportion of organisms indicates lower overall environmental quality

Number of qualitative EPT taxa—qualitative measure of habitat diversity and water quality; measures richness of mayfly (Ephemeroptera), stonefly (Plecoptera), and caddisfly (Trichoptera) taxa.

References: OEPA 1989, USEPA 1992b

Advantages: Bioassessment provides indications of cumulative impacts of multiple stressors, not just water quality. Biological community condition reflects both short- and long-term effects and directly evaluates the condition of the habitat and water resource. Biological data can be interpreted based on regional reference condition where single reference sites are lacking or inadequate.

Disadvantages: Additional chemical and biological (toxicity) testing is usually needed to identify causal agent.
Analyte capability: Invertebrates
Method: Macroinvertebrate aggregated index for streams (MAIS)
Description: MAIS is a rapid bioassessment protocol similar to ICI. MAIS scores are based on macroinvertebrates collected with a prescribed number of kick and dip net sweeps. Organisms are identified to the family (rather than genus) level. Family-level identifications require more training than order level (e.g., EPT, etc.) but can be performed by individuals with an intermediate level of skill. Once macroinvertebrates are collected, identified, and enumerated, an MAIS index score ranging between 0 and 18 is generated from 9 aggregated macroinvertebrate metrics that describe the diversity and abundance of different groups. In the mid-Atlantic highlands, four narrative categories are assigned based on the scores 0–7 = very poor, 8–11 = poor, 12–15 = good, 16–18 = very good.

Measured endpoints:
The nine biological metrics that compose the final MAIS index score:
  • EPT richness: number of caddisfly, stonefly and mayfly families
  • Ephemeroptera: number of mayfly families
  • Percent Ephemeroptera: % abundance of mayflies
  • Percent five dominant taxa: five most dominant taxa combined
  • Simpson Diversity Index: integrates richness and evenness
  • Modified Hilsenhoff Biotic Index: Integrates abundance and taxa richness; taxa in latter are weighted by pollution tolerance scores
  • Number of intolerant taxa: number of families with tolerance values of 5 or less (very sensitive)
  • Percent scrapers: relative abundance of benthos that feed on periphyton
  • Percent haptobenthos: relative abundance of benthos that require clean, coarse, firm substrates

References: Johnson 2006

Advantages: Bioassessment provides indications of cumulative impacts of multiple stressors, not just water quality. Biological community condition reflects both short- and long-term effects and directly evaluates the condition of the habitat and water resource. Biological data can be interpreted based on regional reference condition where single reference sites are lacking or inadequate.

Disadvantages: Additional chemical and biological (toxicity) testing is usually needed to identify causal agent.
Analyte capability: NA
Method: Benthic infaunal abundance
Description: This marine-specific method compares the relative abundance of site major taxa to reference-area taxa. A site is considered impacted if (1) the abundance of the Class Crustacea, Class Polychaeta, and Phylum Mollusca in the test sediment is statistically different (t test @ 0.05, www.socialresearchmethods.net/kb/stat_t.php) from the “reference sediment” and (2) the “test sediment” has less than 50% of any one of the major taxa relative to the reference sediment’s mean abundance of any one of the major taxa.

Measured endpoints: Abundance of the following major taxa: Class Crustacea, Class Polychaeta, and Phylum Mollusca.

References: Washington Administrative Code 173-204
Advantages: Bioassessment provides indications of cumulative impacts of multiple stressors, not just water quality. Biological community condition reflects both short- and long-term effects and directly evaluates the condition of the habitat and water resource. Biological data can be interpreted based on regional reference condition where single reference sites are lacking or inadequate.

Disadvantages: Additional chemical and biological (toxicity) testing is usually needed to identify causal agent.
Analyte capability: NA

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Appendix C-T7. Surface-water quality models (fate and transport) Print this table

Method: Level I
Description: Calculates the equilibrium distribution of a fixed quantity of conserved (i.e., nonreacting) chemical in a closed environment at equilibrium with no degrading reactions, no advective processes, and no intermediate transport processes.

Equilibrium: 1-dimensional
Version: March 2004
Format: Windows

References: Mackay 2001
Website: www.trentu.ca/academic/aminss/envmodel/models/models.html
Advantages: None reported.

Disadvantages: None reported.
Analyte capability: Organo-chlorines, other organic compounds
Method: Level II
Description: Models a situation in which a chemical is continuously discharged at a constant rate and achieves a steady-state and equilibrium condition, at which the input and output rates are equal.

Equilibrium: 1-dimensional
Version/released: February 17, 1999
Format: Windows

References: Mackay 2001
Website: www.trentu.ca/academic/aminss/envmodel/models/models.html

Advantages: None reported.

Disadvantages: None reported.
Analyte capability: Organo-chlorines, other organic compounds>
Method: Level III
Description: Describes the fate of a chemical continuously discharged at a constant rate and has achieved a steady-state condition in which input and output rates are equal but equilibrium between media is not assumed.

Steady state: 1-dimensional
Version/released: February 7, 2004
Format: Windows

References: Mackay 2001
Website: www.trentu.ca/academic/aminss/envmodel/models/models.html
Advantages: None reported.

Disadvantages: None reported.
Analyte capability: Organo-chlorines, other organic compounds
Method: Quasi
Description: Describes the steady-state behavior of an organic chemical in a lake subject to chemical inputs by direct discharge, inflow in rivers, and deposition from the atmosphere.

Steady state: 1-dimensional
Version/released: February 8, 2002
Format: Windows/Basic

References: Mackay 2001; Mackay, Joy, and Patterson 1983
Website: www.trentu.ca/academic/aminss/envmodel/models/models.html
Advantages: None reported.

Disadvantages: None reported.
Analyte capability: Organo-chlorines, other organics, metals
Method: Sediment
Description: Calculates the water-sediment exchange characteristics of a chemical based on its physical chemical properties and total water and sediment concentrations.

Steady state: 1-dimensional
Version/released: February 2004
Format: Windows

References: Rueber et al. 1987, Mackay 2001
Website: www.trentu.ca/academic/aminss/envmodel/models/models.html
Advantages: Useful for determining the likely fate of a chemical subject to transfer between a water column and a sediment compartment.

Disadvantages: None reported.
Analyte capability: Organo-chlorines, other organic compounds
Method: Exams
Description: Interactive computer software for formulating aquatic ecosystem models and rapidly evaluating the fate, transport, and exposure concentrations of synthetic organic chemicals.

Steady state to dynamic: 1-dimensional
Version/released: 2.98.04.06/2005
Format: Fortran

Website: www2.epa.gov/exposure-assessment-models/exams-version-index
Advantages: A “legacy” Fortran routine that is used extensively to model the fate, transport, and exposure concentrations of synthetic organic chemicals, including pesticides, industrial materials, and leachates from disposal sites. Often used to predict hazards of pesticides a priori. Can be integrated seamlessly into other model platforms.

Disadvantages: Steep learning curve and requires numerous input variables, some of which may have to be assumed.
Analyte capability: Organo-chlorines, other organic compounds
Method: SMPTOX4
Description: SMPTOX is a steady-state flow model that simulates transport and fate of chemical pollutants in suspended solids, dissolved in the water column, and in sediments.

Steady state: 1-dimensional
Version/released: 1995
Format: DOS

Supporting agency/developer: USEPA Center for Exposure Assessment Modeling

Reference: USEPA 1995b
Advantages: None reported.

Disadvantages: Steady-state predictions only. Nonpoint source loadings cannot be simulated. Does not consider daughter products or processes. Process kinetics is not simulated.
Analyte capability: Organo-chlorines, metals
Method: MIKE11-WQMIKE21-WQMIKE3W
Description: Generalized modeling package-1D(/2D/3D) water quality module.

Dynamic: 1-dimensional to 3-dimensional
Format: Geographic information system (GIS)

Supporting agency/developer: Danish Hydraulic Institute

Website: www.mikebydhi.com
Advantages: None reported.

Disadvantages: None reported.
Analyte capability: Hydraulic models of rivers and floodplains
Method: RATECON (Great Lakes Rate Constant Model)
Description: Rate constant model for chemical dynamics, designed to predict the fate and recovery times of contaminants in the Great Lakes; similar to QWASI but not using the fugacity concept.

Dynamic: 1-dimensional
Version/released: 1991
Format: Basic

References: Mackay et al. 1994
Website: www.trentu.ca/academic/aminss/envmodel/models/models.html
Advantages: None reported.

Disadvantages: None reported.
Analyte capability:
Developing a complete quantification of all processes, thus providing a decision support tool to improve management and remediation of aquatic systems by linking loading to concentration
Method: Watershed Analysis Risk Management Framework (WARMF)
Description: Provides a roadmap to calculate total maximum daily loads for most conventional pollutants.

Dynamic: 1-dimensional to 2-dimensional
Version: 6.1/September 1, 2005
Format: Windows 95/98/ME/2000xp

Website: www.epa.gov/athens/wwqtsc/html/warmf.html
Advantages: See website.

Disadvantages: None reported.
Analyte capability: Coliform, TSS, biological oxygen demand, nutrients
Method: Water Quality Analysis Simulation Program (WASP6)
Description: Helps users interpret and predict water-quality responses to natural phenomena and man-made pollution for various pollution management decisions.

Dynamic: 1-dimensional to 3-dimensional
Version/released: 7.41/June 7, 2010
Format: Windows 95/98/ME/2000xp

Website: www.epa.gov/athens/wwqtsc/html/wasp.html
Advantages: None reported.

Disadvantages: None reported.
Analyte capability: Metals (Hg), organo-chlorines, other organics
Method: AQUATOX–Dynamic, with food web
Description: Predicts the fate of various pollutants, such as nutrients and organic chemicals, and their effects on the ecosystem, including fish, invertebrates, and aquatic plants.

Steady state to dynamic: 2-dimensional
Version/released: 3.0
Format: Windows Website: http://water.epa.gov/scitech/datait/models/aquatox/index.cfm
Advantages: None reported.

Disadvantages: None reported.

Analyte capability: Organo-chlorines, other organics
Method: ECOFATE
Description: Includes a steady-state and a time-dependent model of the mass transport and food-web bioaccumulation of organic chemicals in aquatic ecosystems. It can be used to assess the distribution of chemical concentrations in water, sediment, and aquatic biota in real-world aquatic ecosystems.

Steady state to dynamic: 1-dimensional to 2-dimensional
Version/released: 1998
Format: Visual Basic for Windows 3.x platform

Website: http://research.rem.sfu.ca/toxicology/models/models.htm
Advantages: None reported.

Disadvantages: None reported.
Analyte capability: Organics

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Appendix C-T8. Fish uptake calculation methods and models Print this table

Method: Sediment, receptor tissue equilibrium partitioning (EqP) or biota-sediment accumulation factor (BSAF)
Method: Sediment, diet, water, receptor tissue bioaccumulation factor (BAF)
Description: Ratio of the concentration in aquatic organism to its concentration in specific media (water, sediment, prey). Bioaccumulation is net uptake and retention of a chemical in an organism from all routes of exposure (diet, dermal, and respiratory) and any source (water, sediment, food) as typically occurs in the natural environment. Measured endpoints include concentration in organism and concentration in water (all sources). It can be conducted in laboratory or field.

Test organisms include all aquatic and aquatic-dependent wildlife.

References: USEPA n.d. “ECOTOX,” Weisbrod et al. 2007
Advantages: Simple estimation tool that can use default USEPA values or develop site-specific factors based on measured tissue and other site media concentrations. Simple and easily performed using spreadsheet functions.

Disadvantages: BSAFs derived from literature sources do not reflect site-specific conditions. Site-derived BSAFs implicitly assume that all exposures occur within the area under investigation.
Analyte capability: All classes of chemicals but especially applicable to divalent cation uptake
Method: Water, receptor tissue bioconcentration factor (BCF)
Description: Bioconcentration is the process by which a chemical is retained in an aquatic organism following its absorption through respiratory and dermal surfaces from the surrounding water (does not include dietary exposure). Bioconcentration is measured under controlled laboratory conditions.

Measured endpoints include concentration in organism, concentration (total and dissolved) in water.

Laboratory exposure test organisms are typically fish, amphibians, and reptiles.

References: USEPA n.d. “ECOTOX”
Advantages: Simple estimation tool that can use default USEPA values or develop site-specific factors based on measured tissue and other site media concentrations. Simple and easily performed using spreadsheet functions.

Disadvantages: BCFs derived from literature sources may not reflect site specific conditions. Site-derived BCFs implicitly assume that all exposures occur within the area under investigation.
Analyte capability: All classes of chemicals
Method: Predator tissue, prey tissue biomagnification factor (BMF)
See Appendix C-T5.
Method: Estimation Program Interface (EPI) Suite™
Description: The EPI Suite is a Windows-based suite of physical/chemical property and environmental fate estimation programs developed by the USEPA Office of Pollution Prevention Toxics and Syracuse Research Corporation.

Website: www.epa.gov/opptintr/exposure/pubs/episuite.htm
Advantages: Facilitated by a database of >40,000 chemicals.

Disadvantages: A screening-level tool not to be used if acceptable measured values are available.
Analyte capability: Screening-level estimates of physical/ chemical and environ-mental fate properties, the building blocks of exposure assessment
Method: Gobas kinetic food web model
See Appendix C-T5.
Method: Food web Bioaccumulation and Aquatic System Simulator (BASS)
See Appendix C-T5.
Method: Food web Spreadsheet For Environmental Risk Assessment For Mercury (SERAFM)
See Appendix C-T5.
Method: Tissue/direct tissue residue assessments
See Appendix C-T5.
Method: Plasma/direct plasma residue assessments
See Appendix C-T5.
Method: Tissue/in situ bioaccumulation studies
Description: Surrogate receptor organisms are placed at the target site in cages either in contact with or directly above the sediment. After a specified period of time, the organisms are harvested and the tissues analyzed for COCs.

Measured endpoints include survival, tissue residue, COCs, and lipids.

Test organisms are benthic organisms, small fish, and clams.

References: USEPA 2000a
Advantages: Site-specific exposures that integrate contaminant uptake over all media. Relatively easy and inexpensive to implement.

Disadvantages: Surrogate organisms are most often those used in bioassays and may not reflect uptake by site-specific organisms.
Analyte capability: All classes of chemicals<
Method: Tissue/dietary assimilation efficiencies
Description: Absorption efficiency represents the net result of absorption and elimination. Feeding studies are designed to estimate absorption efficiency based on accumulated chemical residues. The fraction of the chemical retained in the organisms relative to that ingested is the assimilation efficiency.

Measured endpoints are COC levels in food and residual in feces. Also may involve measuring chemical levels in target organism tissue, organelles, and developing fetus.

Test organisms include all, but most typically fish, birds, and mammals.

References: Erickson et al. 2008
Advantages: Most direct measure of how much of a contaminant in food is retained by the target organism.

Disadvantages: Difficult to adequately capture fish fecal matter. Useful for birds and mammals but can be time- and resource-intensive. Expensive and requires special laboratory procedures and animal husbandry.
Analyte capability: All classes of chemicals
Method: Direct tissue residue analysis
See Appendix C-T5.

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Appendix C-T9. Direct pore-water sampling devices Print this table

Calculation methods and models
Method: Bioaccumulation and biomagnification
Description: Estimation methods using measured or estimated COC in food or prey and published accumulation factors from the literature.

Measurement endpoints: Estimated concentrations in receptor organisms.

Test organisms: All.

References: USEPA 2006b, Weisbrod et al. 2007, Van Wezel et al. 2000
Advantages: Simple, inexpensive method to estimate exposure levels. Readily implementable.

Disadvantages: Does not include site-specific factors, including bioavailability.
Analyte capability: All chemical classes
Method: USEPA allometric food intake assessment
Description: Allometric equations developed to estimate total oral dose of a chemical based on intake of food, water, or sediment with consideration of species home range, weight, consumption rates, and food preferences.

Measurement endpoints: Daily oral dose to receptor organism.

Test organisms: Originally developed for select birds and mammals, have been applied to a wide range of species including reptiles and marine mammals.

References: Baron, Sample, and Suter 1999; Sample and Suter 1999
Advantages: Simple, inexpensive method to estimate exposure levels. Can be adjusted to consider bioavailability where information is available. Requires only a literature search and a spreadsheet calculation.

Disadvantages: Does not include site-specific factors, including bioavailability.
Analyte capability: All chemical classes
Method: Bioenergetics-based modeling
Description: Models constructed to estimate exposure based on estimating oral intake from the target receptors’ bioenergetic requirements, contaminant assimilation efficiencies, tissue conversion factors, and clearance rates.

Measurement endpoints: Estimated tissue residue concentrations.

Test organism categories: Principally applied to avifauna.

References: Norstrom et al. 2007, Nichols et al. 2004, Karasov et al. 2007
Advantages: Moderately complex modeling exercise that depends on effective parameterization of the model equations. Requires collaboration between knowledgeable bird ecologist, toxicologist, and computer modeler.

Disadvantages: Model parameters are not available for all species, introducing uncertainty into the model estimates.
Analyte capability: Persistent organic compounds
Direct measures
Method: Bioaccumulation and biomagnification
Description: Evaluates uptake of a chemical into a predator relative to that of its prey. For HOCs, the concentrations are lipid normalized. For metals, the units are mg/kg wet weight. Biomagnification is said to occur when the BMF > 1.

Measurement endpoints: Concentration in predator, concentration in prey % lipids.

Test organism categories: Can be used for all aquatic and aquatic-dependent wildlife.

References: Foley et al. 1988; Bergman et al. 1994; Leonards et al. 1997; Wolfe, Schwartzbach, and Sulaiman 1998
Advantages: May be used to estimate concentrations in higher trophic level fish, birds, or mammals based on measured or previously reported BMFs or to validate more complex food web models.

Disadvantages: BMFs derived from literature sources may not reflect site-specific conditions. Site-derived BMFs implicitly assume that all exposures occur within the area under investigation.
Analyte capability: All
Method: Field tissue residue and effects assessments
Description: Receptor organisms are harvested from the field and brought to the laboratory and tissues are measured for target chemical(s). Field observations can also include clutch size, eggshell thinning, fledge success.

Measurement endpoints: Tissue residue COCs, lipids, whole body, clutch size, eggshell thickness, fledge success, subcellular biomarkers.

Test organism: Most commonly applied to bird species. Whole-body measures not applicable for T&E species.

References: Custer and Custer 1995, Custer et al. 1999, Anteau et al. 2007, Overman and Krajicek 1995
Advantages: Integrates all pathways of exposure and provides a direct number for assessing risks.

Disadvantages: Assumes all prey consumed are within contaminated area, which may not be valid for all predators. Not suitable for T&E species. Moderately to difficult to implement. Requires capture of suitable numbers and types of target receptors for evaluation in statistically meaningful way.
Analyte capability: All chemical classes
Method: Site-specific in situ dietary intake/effect studies
Description: Nest boxes are placed immediately proximal to a contaminated site and monitored for reproductive effects. Measures include gut content identification and COC analysis, tissue analyses, clutch size, eggshell thickness, and reproductive success.

Measurement endpoints: Adult growth (weight), mortality, clutch size, eggshell thickness, fledge success.

Test organisms: Tree swallows, house wrens.

References: Custer et al. 1998, 2001, 2003, 2005
Advantages: Relatively inexpensive. Integrates multiple chemicals in prey organisms with direct measures of site-specific uptake and effects.

Disadvantages: Assumes dose is wholly dependent on foraging occurring within the contaminated site. Good assumption for large sites, not practicable for small sites.
Analyte capability: All chemical classes>
Method: Site-specific ex situ dietary intake/effect studies
Description: Fish or other prey items from the contaminated site are collected, formulated into diets, and fed to surrogate species.

Measurement endpoints: Adult growth (weight), assimilation efficiency, COC uptake, mortality, litter or clutch size, pup weight gains, eggshell thickness

Test organisms: Minks and otters.

References: Sample and Suter 1999; Smits, Wobeser, and Schiefer 1995; Bleavens et al. 1984
Advantages: Integrates multiple chemicals in prey organisms with direct measures of uptake and effects.

Disadvantages: Expensive and can take considerable time if multiple generations are involved. Not suitable for T&E species.

Analyte capability: All chemical classes>

Method: Direct toxicity assessments
Description: Target wildlife species are directly exposed to COCs in controlled laboratory environments.

Measurement endpoints: Adult growth (weight), assimilation efficiency, COC uptake, mortality, litter or clutch size, pup weight gains, eggshell thickness.

Test organisms: All species.

References: Flemming et al. 1985, Clark et al. 1987, Camardese et al. 1990

Advantages: Integrates multiple chemicals in prey organisms with direct measures of uptake and effects.

Disadvantages: Expensive and can take considerable time if multiple generations are involved. Not suitable for T&E species.

Analyte capability: All chemical classes
Method: Plasma COC assessments
Description: Plasma from receptor organisms is collected from the field, brought to the laboratory, and measured for target chemical(s).

Measurement endpoints: Plasma COCs, percent lipids.

Test organisms: Principally used to assess chemical levels in T&E species and/or juveniles.

References: Elliot et al. 2001, Bowerman et al. 2003, Strause et al. 2007
Advantages: Integrates all pathways of exposure and provides a direct number for assessing risks without killing receptor.

Disadvantages: Sampling generally limited to few individuals. Resource-intensive. Plasma COCs not associated with specific toxicological effects. Moderately to difficult to implement. Requires capturing or accessing receptors and collecting samples, which may inflect damage on target species.
Analyte capability: All chemical classes
Method: Fur or feather COC assessment
Description: Field collected fur or feathers are collected and analyzed for target COCs.

Measurement endpoints: COCs, percent lipids.

Test organisms: Principally used to assess chemical levels in T&E species and/or juveniles.

References: Monteiro and Furness 1997; Scheuhammer et al. 1998; Burger, Lavery, and Gochfeld 1994, Lundstedt-Enkel et al. 2005
Advantages: Nonintrusive method for collecting and evaluating presence of COCs in wildlife. Relatively simple and low cost.

Disadvantages: None reported.
Analyte capability: All chemical classes
Method: Dietary assimilation efficiencies
Description: Absorption efficiency represents the net result of absorption and elimination. Feeding studies are designed to estimate absorption efficiency based on accumulated chemical residues. The fraction of the chemical retained in the organisms relative to that ingested is the assimilation efficiency.

Measurement endpoints: Chemical levels in food and residual in feces. Also may involve measuring chemical levels in target organism tissue, organelles, and developing fetus.

Test organisms: All, but most typically fish, birds, and mammals.

References: None
Advantages: Most direct measure of how much of a contaminant in food is retained by the target organism.

Disadvantages: Difficult to adequately capture fish fecal matter. Useful for birds and mammals but can be time- and resource-intensive.
Analyte capability: All chemical classes


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