Research Overview
TBI supported the Master's thesis work by Braden Hannah
(completed Spring, 2003), supervised by David W. Mogk.
This work was focused on characterization of the mineralogy
of acid-sulfate hot springs known to host Sulfolobus
from the Rabbit Creek and Ragged Hills (Norris Geyser
Basin) areas in Yellowstone National Park. Field work
included: detailed mapping of the physical distribution
of hot springs and related features in these areas;
regular sampling of natural waters for geochemical analysis;
monitoring temperature and pH of the natural waters;
and collection of mineral samples from sediments suspended
in the spring waters, from the pool basins, and from
surrounding soils. Analytical studies included scanning
electron microscopy, energy dispersive spectroscopy,
and X-ray diffraction analysis of the mineral species,
including imaging of mineralogical textural features
and their relations to microbes and their biofilms.
The Rabbit Creek mineralogy includes kaolinite, hematite
and varieties of silica species (quartz, opal-A, opal-C,
and opal CT), whereas the Ragged Hills location also
contains alunite. Residual volcanic glasses also are
host to trace minerals such as apatite, zircon, and
ilmenite. Analysis of differing grain sizes shows that
the finest suspended particles are typically opal-A
(i.e. disordered), whereas coarser fractions in the
water column and basin sediments contain also opal C
or CT and ordered quartz.
Complementary experimental studies (in progress) are
investigating the relationship of specific mineral phases
(sulfur, quartz, opal, hematite, and kaolinite) as potential
substrates for microbial attachment, and as possible
sources of nutrients, energy, and metabolic by-products.
Further characterization of natural mineral species
and geochemical analysis of natural waters will continue
to develop baseline databases from which to compare
seasonal and long-term variation of the physico-chemical
state of these systems. More detailed mineralogical
studies are in progress. In addition, analytical studies
will expand to include Time-of- Flight SIMS analysis
of mineral substrates to search for diagnostic biomarkers;
X-ray photoelectron spectroscopy to determine chemical
state of the surfaces of mineral substrates; and atomic
force microscopy to obtain more detailed images of the
surfaces of minerals, particularly where these surfaces
may be mediated by microbial attachment