Print this pageInvestigating 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.