Superfund Research Program

Microscale Evaluation of Pollutant Bioavailability Leading to Structured Models for Contaminant Fate in Porous Media

Project Leaders: William C. Ghiorse, Eugene L. Madsen, Michael L. Shuler
Grant Number: P42ES005950
Funding Period: 1995 - 2000

Project-Specific Links

Final Progress Reports

Year:   1999 

Project investigators have been improving microscopic methods for visualizing the fate of toxic metals in bacterial biofilms. Progress includes development of new procedures for 3 dimensional analyses by CLSM. Complex communities of bacterial cells and their polymers were imaged by stereo overlay procedures using specimens embedded in agarose gels and stained with acridine orange. This new technology allows for 3D-positioning of bacterial cells and metabolic particles in the biofilm. Bacterial exopolymers similar to those in the biofilm matrix were studied at the chemical level to better understand the basis for metal binding and the ability to bind and transport toxic metal sand organic chemicals such as phenanthrene. Results contributed significant progress in the ability to understand the distribution of microorganisms vis-à-vis the pollutants which they may transform or mobilize, as well as a capability to model key bioremediation processes. A gamma function model was further explored as a tool for scaling up understanding of chemical fate and interactions at Superfund and brownfield sites.