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2004 Progress Report: Co-Contaminant Effects on Risk Assessment and Remediation Activities Involving Urban Sediments and Soils: Phase II
EPA Grant Number: R828771C001Subproject: this is subproject number 001 , established and managed by the Center Director under grant R828771
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: HSRC (2001) - Center for Hazardous Substances in Urban Environments
Center Director: Bouwer, Edward J.
Title: Co-Contaminant Effects on Risk Assessment and Remediation Activities Involving Urban Sediments and Soils: Phase II
Investigators: Ball, William P. , Bouwer, Edward J.
Current Investigators: Ball, William P. , Bouwer, Edward J. , MacKay, Allison
Institution: Johns Hopkins University
Current Institution: Johns Hopkins University , University of Connecticut
EPA Project Officer: Lasat, Mitch
Project Period: October 1, 2001 through September 30, 2007
Project Period Covered by this Report: October 1, 2003 through September 30, 2004
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (2001)
Research Category: Hazardous Waste/Remediation
Description:
Objective:Contaminated sites typically involve complex mixtures of contaminants, the fate of which is affected both by biochemical interactions that impact microbial attenuation (e.g., cometabolic effects, competitive inhibition, and toxicity) and competitive adsorption on solid phases (that can complicate mass transfer rates during desorption). Because sediment- or soil-bound contaminants usually are not bioavailable (from either a remediation or biotoxicity viewpoint), successful prediction and assessment of fate and transport require a full accounting and integration of the sorption effects.
The overall objective of this research project is to evaluate when a specific consideration of chemical interactive effects is needed (as a function of site conditions) and to develop and test improved models for simulating and predicting contaminant transport and fate under conditions that involve multiple chemical contaminants or additives. The phase II objective is to develop new data and modeling approaches that can be applied to better predictions of the combined effects of both sorption and biodegradation of organic contaminants, with a focus on solid phases typical of urban environments and on chemical fate in the presence of complex organic contaminant mixtures. Specific subobjectives of the project are to: (1) apply modeling simulations to evaluate the impact of co-contaminants on sorption and on rates of desorption and biodegradation; (2) experimentally evaluate sources and mechanisms of nonlinear and competitive sorption in environmentally relevant solids; and (3) develop and evaluate alternative (i.e., mechanistically based) approaches for quantifying overall rates of desorption and biodegradation in contaminated soil/water environments that include mixtures of contaminants. The first year effort has been restricted to model review and development. Laboratory experiments are planned for the second year.
Progress Summary:Our experimental approach for this project continues to be based on a combination of computer modeling and laboratory evaluation. No laboratory experiments have been conducted to date for phase II of the project ; however, considerable progress has been made in the area of modeling. Modeling has been conducted to better understand how sorption, mass transfer, biodegradation, and the presence of other compounds affect the fate of contaminants in sorbent-water batch systems. This effort has been accomplished primarily by a postdoctoral associate who has worked nearly full time on this project since his arrival at The Johns Hopkins University in mid January of 2004 (Nathan W. Haws). Dr. Haws came to The Johns Hopkins University from West Lafayette, Indiana, after receiving his Ph.D. from Purdue University. On this project, Dr. Haws has further developed the batch-scale numerical model that was adapted and used by Isam Sabbah, the previous postdoctoral associate working on phase I of this project. Dr. Haws has expanded the model to account for the effects of co-contaminants on sorption (using the ideal adsorbed solution theory) and biodegradation (including competitive inhibition, co-metabolic rate enhancements, and toxicity effects on biomass growth). He has used the model to investigate how different sorption, mass transfer, and biodegradation limitations of bioavailability change the sensitivity of model predictions with respect to the presence of co-contaminants. This study has been extended to explore the sensitivity of modeling results to modeling approaches that use varying levels of complexity to represent sorption, intraparticle mass transfer, and biodegradation. This extended study used a suite of 18 models ranging from computationally simple approaches that invoked equilibrium, linear sorption, and first-order biodegradation, to much more sophisticated and highly parameterized models that considered nonlinear, multidomain sorption and mass transfer, Monod biodegradation kinetics, and co-contaminant effects.
The results of the study show that the sensitivity to the different modeling approaches varies depending on which processes (sorption, mass transfer, or biodegradation) control the overall contaminant bioavailability. For example, the simulations are insensitive to the type of sorption model used in systems with low sorption strength and slow biodegradation rates. For such systems, however, predictions can be very sensitive to the model’s biodegradation component, including the consideration of co-contaminant effects on biodegradation rates. Conversely, the behavior of systems with rapid biodegradation will be strongly dependent on mass transfer effects, including possible impacts of competitive sorption. The sensitivity of the results to the various models also is greater when evaluated in terms of mass removal rather than aqueous phase concentration reduction. These simulation results are being used to explain how the determination of the appropriate level of model complexity, including considerations of co-contaminant effects, can be guided by preliminary assessments of the extent to which the various sorption, mass transfer, and biodegradation processes are expected to control contaminant bioavailability.
Future Activities:Modeling
We will continue our efforts to consider more specifically the role of competitive adsorption on mass transfer and to extend the bioavailability/co-contaminant modeling to systems with one-dimensional advective flow. Dr. Haws has modified a one-dimensional transport model to incorporate co-contaminant effects in a similar way to the batch-scale model discussed previously. Also under consideration is the development of new models for simulating polychlorinated biphenyls (PCB) desorption from sediments under conditions of cyclic resuspension and resedimentation.
Laboratory Experimentation
As outlined in the phase II proposal for this project, we also intend to obtain field samples of harbor sediments and Superfund site soils from collaborating groups, and if personnel time and budget constraints permit, to conduct screening-level sorption equilibrium and rate tests using nonpolar organic chemical probes. In this work, our emphasis will be on testing for sorption nonlinearity and competition. The results of this work will allow us to better relate our continuing modeling sensitivity exercises to actual case scenarios. Also under consideration (as an alternative to the above) is the application of new sediment modeling approaches to the interpretation of some recent experimental results regarding PCB desorption from sediments as obtained by center collaborators at the University of Maryland.
Journal Articles on this Report: 3 Displayed | Download in RIS Format
| Other subproject views: | All 29 publications | 5 publications in selected types | All 5 journal articles |
| Other center views: | All 111 publications | 24 publications in selected types | All 22 journal articles |
| Type | Citation | ||
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Haws NW, Ball WP, Bouwer EJ. Modeling and interpreting bioavailability of organic contaminant mixtures in subsurface environments. Journal of Contaminant Hydrology 2006;82(3-4):255-292. |
R828771C001 (2004) R828771C001 (2005) R828771C001 (Final) |
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Nguyen TH, Sabbah I, Ball WP. Sorption nonlinearity for organic contaminants with diesel soot: method development and isotherm interpretation. Environmental Science & Technology 2004;38(13):3595-3603. |
R828771C001 (2004) R828771C001 (2005) R828771C001 (Final) |
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Sabbah I, Ball WP, Young DF, Bouwer EJ. Misinterpretations in the modeling of contaminant desorption from environmental solids when equilibrium conditions are not fully understood. Environmental Engineering Science 2005;22(3):350-366. |
R828771C001 (2004) R828771C001 (2005) R828771C001 (Final) |
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contaminant mixtures, bioavailability, sorption, biodegradation,
competitive adsorption, bioremediation, natural attenuation, toxics, exposure,
hazardous substances, assessment, cleanup, risk communication,
,
ENVIRONMENTAL MANAGEMENT, Water, INTERNATIONAL COOPERATION, TREATMENT/CONTROL, Scientific Discipline, Waste, Health, RFA, PHYSICAL ASPECTS, Brownfields, chemical mixtures, Remediation, Risk Assessment, Risk Assessments, Waste Treatment, Health Risk Assessment, Physical Processes, Hazardous Waste, Contaminated Sediments, Hazardous, Ecology and Ecosystems, environmental justice, exposure assessment, urban environment, Brownfield site, biodegradation, outreach material, brownfield sites, urban sediment, environmental hazards, co-contaminants, human health risk, technical outreach, contaminated sediment, outreach and education, community support, contaminant dynamics, contaminant transport, contaminated soils, sediment transport, chemical exposure, hazardous substance contamination, complex toxic chemical mixtures, exposure, sediment treatment, technology transfer, chemical contaminants, complex mixtures, human exposure, web development
Relevant Websites:
http://engineering.jhu.edu/~dogee/ball
http://engineering.jhu.edu/~dogee/bouwer
Progress and Final Reports:
2002 Progress Report
2003 Progress Report
Original Abstract
2005 Progress Report
Final Report
Main Center Abstract and Reports:
R828771 HSRC (2001) - Center for Hazardous Substances in Urban Environments
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R828771C001 Co-Contaminant Effects on Risk Assessment and Remediation Activities Involving Urban Sediments and Soils: Phase II
R828771C002 The Fate and Potential Bioavailability of Airborne Urban
Contaminants
R828771C003 Geochemistry, Biochemistry, and Surface/Groundwater Interactions
for As, Cr, Ni, Zn, and Cd with Applications to Contaminated Waterfronts
R828771C004 Large Eddy Simulation of Dispersion in Urban Areas
R828771C005 Speciation of chromium in environmental media using capillary
electrophoresis with multiple wavlength UV/visible detection
R828771C006 Zero-Valent Metal Treatment of Halogenated Vapor-Phase Contaminants in SVE Offgas
R828771C007 The Center for Hazardous Substances in Urban Environments (CHSUE) Outreach Program
R828771C008 New Jersey Institute of Technology Outreach Program for EPA Region II
R828771C009 Urban Environmental Issues: Hartford Technology Transfer and Outreach
R828771C010 University of Maryland Outreach Component
R828771C011 Environmental Assessment and GIS System Development of Brownfield Sites in Baltimore
R828771C012 Solubilization of Particulate-Bound Ni(II) and Zn(II)
R828771C013 Seasonal Controls of Arsenic Transport Across the Groundwater-Surface Water Interface at a Closed Landfill Site
R828771C014 Research Needs in the EPA Regions Covered by the Center for Hazardous Substances in Urban Environments
R828771C015 Transport of Hazardous Substances Between Brownfields and the Surrounding Urban Atmosphere