research project details
Project Title: Determination of binding interactions between xenobiotic
chemicals and soil
Investigator(s): J.-M. Bollag
Sponsor: EPA/ORD/NCERQA
Environmental Problem Addressed:
Treatment methods for contaminated soil.
Research Project Objectives:
Expand on both the amount and quality of data available for predicting contaminant fate, estimating environmental risk, and suggesting remediation or pollution prevention options.
Summary:
Immobilization phenomena occurring in soil are of great environmental importance because they may lead to a considerable reduction in the bioavailability and degradation of organic pollutants. The three known mechanisms of contaminant immobilization (sorption, sequestration, and covalent binding), although concurrent, have mainly been studied separately. In this project a novel integrated approach is applied in order to expand on both the amount and quality of data available for predicting contaminant fate, estimating environmental risk, and suggesting remediation or pollution prevention options. The research will use 2,4,6-trinitrotoluene (TNT), anthracene, and 2,4-dichlorophenol as representatives of nitroaromatic compounds, polyaromatic hydrocarbons (PAHs), and chlorinated phenols, which are widespread soil contaminants.
The work will first focus on batch equilibrium experiments involving either short (less than one day) or long (up to 2.5 years) contact times between contaminants and soil. Using this setup it will be possible to distinguish between sorption and sequestration based on the adsorption/desorption kinetics and on the properties of the respective adsorption isotherms as they change with the contact time. Further studies will involve 13C- and/or 15N-labeled pollutants, which will be incubated in soil (up to 2.5 years) to investigate the sequestered and/or covalently bound material. An aerobic respirometer system will be used to measure bioavailability of incubated compounds. Finally, exhaustive extraction with organic solvents, fractionation, and derivatization, soil samples will be analyzed by 13C- or 15N-NMR spectroscopy and other methods to determine the retention sites, chemical character of the retained compounds, and nature of bonds formed. It is expected that this project will set a standard for future research on contaminants immobilized in soil.