Project Summary (1995-2000)

This project is developing a mechanistic understanding of microscale factors controlling the mobility and ultimately the fate of pollutant chemicals in soil and sediment. This is accomplished by developing and applying a combination of microscopic techniques [confocal laser scanning microscopy (CLSM)], based on immunology [fluorescent antibodies], biotechnology [polymerase chain reaction (PCR)], and microautoradiography (MARG) using ¹⁴C-labeled probes. Together these permit study of the microscale distribution of specifically competent biodegrading bacterial populations in relation to other microbiota, soil constituents, and the model organic pollutants (glucose, phenanthrene, naphthalene) being degraded. Similarly, cadmium (Cd) and lead (Pb) are being used for developing CLSM and MARG methods for work on heavy metal distribution. Once methods are fully developed, changes in the bioavailability and distribution of phenanthrene in groundwater sediments (as well as the microscale distribution of Cd and Pb in porous media and biofilms) can be visualized using concurrent probes for specific bacteria, chemicals, and soil particles. In a parallel effort, a computer model is being developed that can use these microscale input parameters to predict the long-term prospects for biodegradation of pollutants, such as polyaromatic hydrocarbons (PAHs), in response to various bioremediation strategies or even no intervention at all. These models will be validated by investigating changes in the macro- and microscale distribution of pollutants in soil and sediments using time-course sorption-desorption experiments and miscible displacement studies.