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Improved approaches for assessing and predicting long-term changes in toxicity and contaminant concentrations in biota


Research Question: Why do biota-sediment accumulation factors (BSAFs) decline with increasing concentration in the sediment?

This behavior is contrary to the expected behavior of BSAFs and we will perform research to determine the cause(s) of this behavior. Potential causes include artifacts rising from conditions in the sediment bioaccumulation tests used to measure the BSAFs and bioavailability of the chemical in the sediments. We will perform bioaccumulation tests with Lumbriculus variegatus on sediment samples from sites contaminated with polychlorinated biphenyls (PCBs). The samples will have a wide range of PCB concentrations and in conjunction with the tests, concentrations of the PCBs in the porewater, bulk sediment, and Lumbriculus variegatus will be measured. These data will then be evaluated to determine if chemical bioavailability is the cause of the decline. Additionally, sediment bioaccumulation tests with Lumbriculus variegatus will be performed with modified testing conditions (the addition of feeding and non-standard organism loading rates) to determine if these factors are involved in the decline of BSAFs.

Research Question: How do we improve and simplify bioaccumulation models for predicting long-term changes in contaminant accumulation following remediation?

Bioaccumulation models will be developed for the Great Lakes National Program Office (GLNPO, Region 5) Ashtabula, and Ottawa River area of concern (AOC) sites where remedial efforts will be soon completed and post-remediation monitoring begun, and for the New Bedford Harbor Superfund site where remedial efforts are in progress. After model calibration and validation, rates of change at the sites will be forecasted for all organisms across the food web and compared with actual changes for each site. From these modeling exercises, we will evaluate scenarios for monitoring programs to most effectively detect (actually measure) changes in chemical residues in fish and shellfish at these sites. Further, we will evaluate the benefits of different levels of model complexity in predicting chemical residues; e.g., does added complexity reduce uncertainty in forecasted changes in chemical residues? As part of the overall bioaccumulation model development, measures of chemical bioavailability will be introduced into the model as they become available. This task is done in collaboration with the Contaminated Sediments - Task Remedy Effectiveness and Task Passive Sampler Development.

Research Question: How can toxicity test methodologies be refined to better reflect likely risk to benthic invertebrates and eliminate confounding factors?

Recent research has indicated that current freshwater sediment toxicity test methods have weaknesses that can lead to artifacts and misinterpretation. Refinements are needed to eliminate these problems and provide site risk assessments with data that can be more confidently identify sediments posing risk to benthic invertebrates. Laboratory studies will be conducted to evaluate and refine feeding rates, substrate and water types, and other aspects of toxicity test procedures to optimize performance and reproducibility. Resulting recommendations will be incorporated into revised EPA procedural guidance documents.

Research Question: What role do non-PAH (polycyclic aromatic hydrocarbons) hydrocarbons play in producing sediment toxicity?

Initial research has indicated that sediment toxicity often attributed to PAHs is actually caused by other co-occurring hydrocarbons, e.g., oil and grease. The implications of this finding are particularly important where sediment contamination stems from sources that are comparatively low in PAH but high in other hydrocarbons (e.g., lubricating oils, petroleum). A joint approach is needed that can account for the toxicities of both PAH and non-PAH hydrocarbons in contaminated sediments. Laboratory toxicity tests with spiked and field collected sediments will be conducted to parse the effects of PAHs and other co-occurring hydrocarbons. Toxicity identification evaluation (TIE)-type experimental approaches will be used to determine how the respective effects of these stressors can be parsed, and the resulting information incorporated into sediment risk assessment.

Research Question: How can bioavailability-based measurements be standardized for routine use in assessing sediment toxicity and monitoring remedy effectiveness for reducing toxicity to benthos?

Other tasks in this project are focused on passive sampling and other bioavailability-based approaches for assessing bioaccumulative contaminants, primarily PCBs. This research will focus on developing and standardizing passive sampling approaches for contaminants whose primary ecological risks are mediated through direct toxicity to benthos. Contaminants of interest include cationic metals in addition to more commonly evaluated organic chemicals such as PAHs. Laboratory toxicity studies will be conducted which incorporate passive sampling technology developed for the field, with additional development and/or miniaturization as required to meet the logistical constraints of the laboratory scale. The goal is to understand the comparative contaminant bioavailability in laboratory and field and relate those measures to organism performance as a bridge to ecological risk.

Rationale and Research Approach:

EPA’s Office of Solid Waste and Emergency Response (OWSER)/Office of Superfund Remediation and Technology Innovation (OSRTI, Superfund) and GLNPO (Region 5) need (note: needs vary between the two program offices): 1) methods and tools to evaluate remedy effectiveness on the short and long term time scales; 2) a better understanding of the pre- and post-remediation exposures to and contaminant concentrations in receptors at contaminated sediment sites to understand the impacts of remediation; 3) research to validate, improve, and simplify food chain bioaccumulation modeling to predict long-term changes in tissue contaminant concentrations, particularly following remediation; 4) improved sediment toxicity test assessment methodologies for pre- and post-remedial conditions; and 5) standardized bioavailability-based measurements for routine use in assessing sediment toxicity and sediment bioaccumulation measurements with benthic invertebrate test species. In this task, research efforts address these needs of the Superfund and GLNPO offices on contaminated sediments.

MED Scientists:

Lawrence Burkhard
Correne Jenson
David Mount
Terry Highland
James Hockett
Dale Hoff
Tylor Lahren
Larry Heinis


Billa, N., D. Hubin-Barrows, T. Lahren, and L.P. Burkhard. 2014. Evaluation of micro-colorimetric lipid determination method with samples prepared using sonication and accelerated solvent extraction methods. Talanta 119:620-622.

Burkhard, L.P., M. Bonnell, K. Borga, D.E. Powell, P. Leonards, D.C. Muir, T.F. Parkerton, and K.B. Woodburn. 2013. Improving the quality and scientific understanding of Trophic Magnification Factors (TMFs). Environmental Science & Technology (Viewpoint), online only at: dx.doi.org/10.1021/es305253r.

Burkhard, L.P., D.R. Mount, T.L. Highland, J.R. Hockett, T. Norberg‐King, N. Billa, S.B. Hawthorne, D.J. Miller, C.B. Grabanski. 2013. Evaluation of PCB bioaccumulation by Lumbriculus variegatus in field‐collected sediments. Environ. Toxicol. Chem.  32(7):1495–1503.

Burkhard, L.P., J.A. Arnot, M.R. Embry, K.J. Farley, R.A. Hoke, M. Kitano, H.A. Leslie, G.R. Lotufo, T.F. Parkerton, K.G. Sappington, G.T. Tomy, and K.B. Woodburn. 2012. Comparing laboratory and field measured bioaccumulation endpoints. Integrated Environmental Assessment and Management 8:17-31.

Burkhard, L.P., J.A. Arnot, M.R. Embry, K.J. Farley, R.A. Hoke, M. Kitano, H.A. Leslie, G.R. Lotufo, T.F. Parkerton, K.G. Sappington, G.T. Tomy, and K.B. Woodburn. 2012. Comparing laboratory-and field-measured biota-sediment accumulation factors. Integrated Environmental Assessment and Management 8:32-41.

Burkhard, L.P., C. Cowan-Ellsberry, M.R. Embry, R.A. Hoke, and K.A. Kidd. 2012. Bioaccumulation data from laboratory and field studies: Are they comparable? Integrated Environmental Assessment and Management 8:13-16.

Walters, D., M. Mills, B. Cade, and L.P. Burkhard. 2011. Trophic magnification of PCBs and its relationship to the octanol-water partition coefficient. Environmental Science & Technology 45:3917-3924.

Burkhard, L.P., P.M. Cook, and M.T. Lukasewycz. 2010. Direct application of biota-sediment accumulation factors. Environmental Toxicology and Chemistry 29:230-236.

Stanley, J.K., A.J. Kennedy, J.D. Farrar, D.R. Mount, and J.A. Steevens. 2010. Evaluation of reduced sediment volume procedures for acute toxicity tests using the estuarine amphipod Leptocheirus plumulosus. Environmental Toxicology and Chemistry 29:2796-2776.

Gobas, F., W. de Wolf, L. Burkhard, E. Verbruggen, and K. Plotzke. 2009. Revisiting bioaccumulation criteria for POPS and PBT assessments. Integrated Environmental Assessment and Management 5:624-637. 

Expected Products:




Sep 30, 2014

The effects of feeding and loading density of Lumbriculus variegatus in the test upon the measured BSAF.

Lawrence Burkhard

Sep 30, 2014

Technical guidance for OSWER on "Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates."

David Mount

Sep 30, 2015

Report on modeling of contaminant behavior at the Ashtabula and Ottawa River AOC sites, and New Bedford Harbor Superfund site.

Lawrence Burkhard

Sep 30, 2016

Report on complexity of models for incorporating chemical bioavailability into forecasting residues in fish and shellfish.

Lawrence Burkhard

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