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A Comprehensive Investigation of the Effects of Organic Geochemistry on the Sorption-Desorption, Sequestration, and Bioavailability of Mixed Organic Contaminants in Subsurface Systems

EPA Grant Number: R825962
Title: A Comprehensive Investigation of the Effects of Organic Geochemistry on the Sorption-Desorption, Sequestration, and Bioavailability of Mixed Organic Contaminants in Subsurface Systems
Investigators: Weber, Walter J.
Institution: University of Michigan - Ann Arbor
Current Institution: University of Michigan
EPA Project Officer: Lasat, Mitch
Project Period: January 1, 1998 through December 31, 2000
Project Amount: $440,748
RFA: Bioremediation (1997)
Research Category: Hazardous Waste/Remediation

Description:

The overarching objective of this study is to establish a rigorous scientific foundation for risk-based decisions regarding acceptable alternative endpoints for soil and sediment remediation. This objective will be addressed by examining and experimentally documenting the multiple roles of the soil and sediment organic geochemistry on the environmental mobility and bioavailability of hydrophobic organic contaminants (HOCs) in systems containing multiple organic solutes.

Approach:

A model mixed waste containing representative compounds from three primary classes of organic contaminants will be investigated. These classes include polycyclic aromatic hydrocarbons (phenanthrene), chlorinated solvents (trichloroethylene) and chlorinated aromatic hydrocarbons (dichlorobenzene). The research will focus on the effects of soil organic geochemistry in multi-contaminant systems on: i) HOC sorption-desorption hysteresis, desorption rates, and sequestration; ii) the subcritical water extractability of sorbed HOCs; iii) the bioavailability of sorbed HOCs to bacteria and to earthworms and the relationship of bioavailability to subcritical water extractability; and iv) the effect of cumulative solute residence time on the sorbent or so-called "aging," on each of the foregoing.

Expected Results:

The sorption-desorption studies should result in delineation of competitive effects that occur when mixtures of contaminants coexist in subsurface systems. The observed sorption-desorption characteristics, coupled with measurements of subcritical water extractability and bioavailability are expected to yield specific correlations of contaminant behavior in such systems to the organic geochemistry of soils and sediments. The overall results of this multi-pronged investigation should comprise the basis for a robust scientific understanding of factors controlling contaminant sequestration, a sufficiently rigorous scientific basis for determination of risk-based alternate remediation endpoints for contaminated subsurface environments. The results of the work should significantly enhance our ability to conduct risk assessments on contaminated sites. HOCs that become irreversibly sequestered in soils, or that are so strongly bound that they desorb in insignificant or environmentally assimilable amounts over extended periods of time, may comprise sources of minimal exposure and thus minimal risk. A scientifically sound fundamental understanding of soil/sediment properties and other related environmental factors that inhibit sorption reversibility, and thus limit the mobility and bioavailability of sorbed contaminants will be established through this research. This in turn will comprise the requisite basis for and facilitate the establishment of rational risk-based decisions regarding alternative remediation endpoints.

Publications and Presentations:

Publications have been submitted on this project: View all 13 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 3 journal articles for this project

Supplemental Keywords:

cleanup, restoration, chemical transport, exposure, risk, environmental chemistry, biology, geology, environmental engineering. , Ecosystem Protection/Environmental Exposure & Risk, Water, Scientific Discipline, Waste, RFA, chemical mixtures, Ecosystem/Assessment/Indicators, Biology, exploratory research environmental biology, Geology, Health Risk Assessment, Bioavailability, Chemistry, Environmental Engineering, Environmental Chemistry, Chemical Mixtures - Environmental Exposure & Risk, Ecological Effects - Environmental Exposure & Risk, Ecosystem Protection, Contaminated Sediments, Bioremediation, exposure assessment, risk assessment, organic solutes, subsurface systems, fate and transport, geochemistry, hydrocarbons, hydrophobic organic contaminants, chemical transport, risk-based decisions, contaminated sediment, chlorinated solvents, contaminant release, soil characterization

Progress and Final Reports:
1998 Progress Report
1999 Progress Report
Final Report

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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