Characterization of Coupled Hydrologic-Biogeochemical Processes Using Geophysical Data
EMSL Project ID
6902
Abstract
This is a DOE EMSP-funded project looking at metals sequestration in dynamic flow sediment columns using stimulated sulfate reducing microorganisms. One critical aspect of the project involves destructive evaluation of the sediment columns and the imaging and characterization of the pore scale phenomena (i.e., microbial attachment, iron- and zinc-sulfide precipitates, microbe-metal associations, etc.) using electron microscopy (SEM and TEM) and x-ray diffraction technqiues. Initial results indicate that a substantial amount of metal sulfide precipitation has occurred and that this precipitation can be monitored using non-invasive geophysical techniques. Successful interpretation of the geophysical data collected to date, however, requires an understanding of both the nature and the distribution of the mineral precipitates within the column and how these precipitates affect such things as grain surfaces, pore throat openings, and microbial cell distributions.Having only limited experience with the techniques of electron microscopy, I am hoping to take advantage of both the equipment and expertise of researchers at EMSL in both sample preparation and analysis. The samples are currently maintained in an anaerobic environment within acrylic flow cells (5-cm diameter by 30-cm length) and consist of fluid-saturated, coarse-grained sediments that have been inoculated with sulfate-reducing bacteria (D. vulgaris) and flushed with a solution containing both nutrients and aqueous metals (iron and zinc). The sediments within the flow cells are unconsolidated, and as such, sample preparation and analysis will need to be performed in such a way as to preserve the relative geometry of the grains utilizing fixation techniques available in the literature. Should this proposal be accepted, it is likely that the flow cells will be sealed and transported intact to EMSL at which time destructive analysis will proceed under the guidance and suggestion of EMSL researchers. As noted above, due to the anaerobic nature of the flow cells, access to an anaerobic chamber will be desirable within which the columns can be disassembled and the sediment samples initially prepared for analysis.
Scope addition March 11, 2005 - Jim Amonette = POC:
A rough plan might be as follows:
(1) Prepare the reduced clays in your lab under your direct
supervision. I like your idea of using both nontronite and other
iron-bearing smectites. As the ultimate focus here is on microbially
reduced clays, the need for some fraction of ferric iron is obvious (I
simply assumed that nontronite has more ferric iron per unit mass than
other clays, hence more extensive microbial iron-reduction - an
experiment to be performed later)
(2) Using the analytical equipment shipped from LBNL/UCB, we would find
a small amount of bench space to measure the response of clay-coated
sands. As we will be comparing reduced vs. non-reduced clays, we'll
need to first measure the unaltered material. Once prepared, It takes
about 30 minutes to analyze one sample. It would be worthwhile to look
at several gravimetric enrichments (e.g. 1%, 5%, and 10%) for a given
clay (both reduced and not). Based on my sample holder, the maximum
mass requirements for the clays would be roughly as follows: 1% = 0.64
g clay; 5% = 3.2 g; and 10% = 6.4 g. I can reduce this mass as
required, if it's a problem to produce and rinse this amount.
(3) Analyze the physiochemical characteristics of the reduced clays
(either at EMSL or back at UCB). We should plan on quantifying changes
in surface area, cation exchange capacity, and anything else you feel
is important.
Project Details
Project type
Exploratory Research
Start Date
2004-02-13
End Date
2006-02-27
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Druhan JL, ME Conrad, KH Williams, AL N'Guessan, PE Long, and SS Hubbard. 2008. "Sulfur Isotopes as Indicators of Amended Bacterial Sulfate Reduction Processes Influencing Field Scale Uranium Bioremediation." Environmental Science & Technology 42(21):7842-7849. doi:10.1021/es800414s
Ntarlagiannis D, KH Williams, LD Slater, and SS Hubbard. 2005. "Low-frequency Electrical Response to Microbial Induced Sulfide Precipitation." Journal of Geophysical Research. Solid Earth 110:Article NO. G02009.
Williams KH, A Kemna, MJ Wilkins, JL Druhan, EV Arntzen, AL N'Guessan, PE Long, SS Hubbard, and JF Banfield. 2009. "Geophysical Monitoring of Coupled Microbial and Geochemical Processes During Stimulated Subsurface Bioremediation." Environmental Science & Technology 43(17):6717–6723.
Williams KH, D Ntarlagiannis, LD Slater, A Dohnalkova, SS Hubbard, and JF Banfield. 2005. "Geophysical Imaging of Stimulated Microbial Biomineralization." Environmental Science and Technology 39(19):7592-7600.