9708406 Peters This project is designed to investigate the chemical, physical, and microbiological processes governing the behavior of mixtures of polycyclic aromatic hydrocarbons (PAHs) in NAPL-contaminated soils. PAHs are an important class of organic pollutants that are commonly associated with multicomponent organic contaminants such as coal tar, creosote, and diesel fuel. These contaminants commonly exist as non-aqueous phase liquids (NAPLs). A clear understanding of underlying mechanisms and a comprehensive compositional modeling approach is essential to understanding the impacts of these contaminants on a larger scale and over a long time periods. The specific objectives of this project are: (I) to gain insights about relative biodegradabilities and substrate interactions of PAHs in sole and multi-substrate systems, (ii) to relate biodegradation rates in NAPL contaminated systems to the thermodynamic phase equilibrium and dissolution kinetic processes governing bioavailability, and (iii) to construct an integrated mathematical model of PAH behavior in NAPL-contaminated soils and to validate model formulation through experimentation using PAH-NAPL-contaminated soils. Experimental studies are designed to explore the interrelation of PAH dissolution and biodegradation, and to observe the presence or absence of substrate interactions under various conditions of initial substrate concentrations and proportions. One aim is to ascertain the extent to which kinetic parameters inferred from sole substrate experiments can be used in conjunction with a mathematical formulation that captures substrate interaction effects to describe what happens in a system with multiple PAH substrates. A novel aspect of this work is the use of synthetic NAPLs as models organic liquids to simulate multicomponent contaminants such as coal tars, which permits control in experimental design and analytical characterization.
