A Scientific Rational for Assessing Mobility of Sorbed Contaminants in Subsurface SystemsEPA Grant Number: U915168
Title: A Scientific Rational for Assessing Mobility of Sorbed Contaminants in Subsurface Systems
Investigators: Johnson, Martin D.
Institution: University of Michigan
EPA Project Officer: Packard, Benjamin H
Project Period: January 1, 1997 through January 1, 2000
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1997) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Engineering and Environmental Chemistry , Fellowship - Civil/Environmental Engineering
The objective of this research project is to contribute to the fundamental understanding of the mechanisms that cause slow and often irreversible desorption of contaminants from sediment materials. A rapid screening tool also will be developed to utilize subcritical water extraction to reveal a sediment's specific potential for releasing sorbed compounds.
Phenanthrene has been selected as the probe hydrophobic organic contaminant for this research project. Canadian peat, Michigan peat, Chelsea soil, Lachine shale, and Norwood shale will constitute the natural sorbents representative of a broad range of soil organic matter characteristics. Sorption/desorption experiments will be performed to determine Freundlich isotherm coefficients for the sorbents, and correlations will be developed between soil organic matter macromolecular properties and isotherm parameters. The subcritical water extractability of sorbed phenanthrene from preloaded sorbents will form the basis for using the technique as a rapid screening tool. The rates and efficiencies of phenanthrene extraction will be interpreted from the desorption versus time data, and this information will be correlated to the soil organic matter characteristics. In addition, the subcritical water extraction system will be used to selectively remove the humic type organic matter from soil, and sorption/desorption studies will be conducted with the extracted soils. Extracted soil organic matter will be characterized by gas chromatography/mass spectrometry, and remaining organic matter will be characterized by solid-state 13C nuclear magnetic resonance spectroscopy. Phenanthrene isotherm experiments, with both the extracted and nonextracted soils, should reveal the specific contributions of the humic type organic matter to the sorption process.