Investigating the Impact
of Microbial Interactions with Geologic Media on Geophysical Properties
Caroline A. Davis,
The main goal of this study is to test the hypothesis that microbial interaction with geologic media over short and long term can result in significant changes in the physical properties of the media, potentially imaged using geophysical methodologies. Bacteria are able to alter mineral surface chemistry, affect water-rock interactions, and modify groundwater geochemistry with the potential to induce changes in in-situ physical properties of subsurface geologic media (e.g., porosity and permeability). However, the role that microbes play in altering subsurface geophysical properties has not been fully recognized nor well understood. In order to better understand the relationship between biological processes and the geophysical response of microbially-impacted geologic media, I propose to conduct laboratory studies to: (1) investigate the effect of microbial growth and biofilm formation on electrical properties, (2) investigate the effect of metabolic byproducts of microbial activity such as biosurfactants and organic acids on electrical measurements, and (3) investigate changes in petrophysical properties (e.g., permeability, porosity, surface area) induced by microbe-mineral interactions, and the subsequent effect on geophysical response. Three separate bench-scale column experiments will be set up to investigate the geophysical response of microbially impacted media. The results of this study may have significant implications on the use of geophysics to investigate geomicrobiological studies, hydrocarbon contaminant remediation, and the monitoring of microbial enhanced oil recovery.