Quantitative Thermodynamic Exposure Assessment (Q-TEA) Supporting Resilient Contaminated Sediment Site Restoration

Dr. Todd Bridges | U.S. Army Engineer Research and Development Center



The objective of this project is to develop an integrated, comprehensive capability for evaluating the effect of contaminant influx on the performance of in situ remedies (Q-TEA). Using equilibrium and non-equilibrium passive samplers, in combination, exposure processes relevant to in situ remedy performance will be assessed using experimental mesocosms. Using passive sampling, tissue analysis, and modeling, Q-TEA will be developed to guide and monitor site restoration through in situ remediation. Experiments will be performed to reveal how activated carbon amendments can be most effectively applied to enhance the resilience of in situ sediment remedies challenged by ongoing sources of contamination.

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Technical Approach

The overarching hypothesis for this work is that measured gradients in chemical activity can provide new information about the history and chemodynamics of contaminated sediments. A series of mesocosm experiments will be conducted using field-collected sediments contaminated with PCBs. Both equilibrium and non-equilibrium passive samplers will be used in combination to evaluate changes in contaminant flux and exposure produced by different forms of in situ remediation (e.g., thin-layer caps, amendment with activated carbon) under different chemical influx conditions (e.g., in the presence or absence of ongoing inputs of contaminated sediment). Passive sampler data will be used to quantify chemical processes and exposures to fish and benthic invertebrates included in the mesocosm experiments. Results of these experiments will be used as a basis for developing an enhanced modeling framework, RECOVERY-In Situ, which will add additional processes to the RECOVERY model in order to support design and evaluation of resilient in situ remedies.

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In situ remedies for contaminated sediments offer a number of potential advantages over remedies that predominantly rely upon removal of contaminated sediments, among these benefits are rapid risk reduction and reduced remedy costs. However, in order for these advantages to be fully realized, in situ remedies must provide effective risk reduction over the long term. Achieving this objective requires the development of remedies that are resilient with respect to processes that can compromise or degrade the remedy’s ability to provide risk reduction benefits, e.g., through recontamination of surface sediments. This project will develop insights needed to design resilient remedies while also producing the tools to evaluate, monitor, and guide the management of in situ remedies. These products will directly support remedial project managers, decision making, and remedy selection at contaminated sediment sites. (Anticipated Project Completion - 2018)

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Gilbert, D., G. Witt, F. Smedes, and P. Mayer. 2016. Polymers as Reference Partitioning Phase: Polymer Calibration for an Analytically Operational Approach To Quantify Multimedia Phase Partitioning. Anal. Chem., 88(11):5818-5826.

Jahnke, A., M. MacLeod, H. Wickström, and P. Mayer. 2014. Equilibrium Sampling to Determine the Thermodynamic Potential for Bioaccumulation of Persistent Organic Pollutants from Sediment. Environ. Sci. Technol., 48(19):11352-11359.

Jonker, M.T.O., S.A. van der Heijden, D. Adelman, J.N. Apell, R.M. Burgess, Y. Choi, L.A. Fernandez, G.M. Flavetta, U. Ghosh, P.M. Gschwend, S.E. Hale, M. Jalalizadeh, M. Khairy, M.A. Lampi, W. Lao, R. Lohmann, M.J. Lydy, K.A. Maruya, S.A. Nutile, A.M.P. Oen, M.I. Rakowska, D. Reible, T.P. Rusina, F. Smedes, and Y. Wu. 2018. Advancing the Use of Passive Sampling in Risk Assessment and Management of Sediments Contaminated with Hydrophobic Organic Chemicals: Results of an International Ex Situ Passive Sampling Interlaboratory Comparison. Environ. Sci. Technol., 52(6):3574-3582.

Schäfera, S., C. Antonia, C. Möhlenkamp, E.Claus, G. Reifferscheid, P. Heininger, and P. Mayer. 2015. Equilibrium sampling of polychlorinated biphenyls in River Elbe sediments – Linking bioaccumulation in fish to sediment contamination. Chemosphere, 138:856-862.

Schmidt, S.N., A.P. Wang, P.T. Gidley, A.H. Wooley, G.R. Lotufo, R.M. Burgess, U. Ghosh, L.A. Fernandez, and P. Mayer. 2017. Cross Validation of Two Partitioning-Based Sampling Approaches in Mesocosms Containing PCB Contaminated Field Sediment, Biota, and Activated Carbon Amendment. Environ. Sci. Technol., 51(17):9996-10004.

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Points of Contact

Principal Investigator

Dr. Todd Bridges

U.S. Army Engineer Research and Development Center (ERDC)

Phone: 601-634-3626

Fax: 601-634-3528

Program Manager

Environmental Restoration