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| Titel |
Does the presence of bacteria effect basaltic glass dissolution rates? 1: Dead Pseudomonas reactants |
| VerfasserIn |
Gabrielle J. Stockmann, Liudmila S. Shirokova, Oleg S. Pokrovsky, Eric H. Oelkers, Pascale Benezeth |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035399
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| Zusammenfassung |
| Basaltic glass and crystalline basalt formations in Iceland have been suggested
for industrial CO2 storage due to their porous and permeable properties and high
reactivity. Acid CO2-saturated waters in contact with basaltic glass will lead to
rapid dissolution of the glass and release of divalent cations, (Ca2+, Mg2+, Fe2+)
that can react to form stable carbonates and thereby trap the CO2. However, the
basalt formations in Iceland not only contains glass and mineral assemblages, but
also host microbiological communities that either by their presence or by active
involvement in chemical reactions could affect the amount of basaltic glass being
dissolved and CO2 being trapped. Samples of natural bacteria communities from
the CO2 storage grounds in Iceland were collected, separated, and purified using
agar plate technique and cultured under laboratory conditions in nutrient broth-rich
media. Heterotrophic aerobic Gram-negative strain of Pseudomonas reactants was
selected for a series of flow-through experiments aimed at evaluation of basaltic glass
dissolution rate in the presense of increasing amounts of dead bacteria and their lysis
products.
The experiments were carried out using mixed-flow reactors at pH 4, 6, 8 and 10 at 25 ºC.
Each of the four reactors contained 1 gram of basaltic glass of the size fraction 45-125 μm.
This glass was dissolved in ~ 0.01 M buffer solutions (acetate, MES, bicarbonate and
carbonate+bicarbonate mixture) of the desired pH. All experiments ran 2 months, keeping
the flowrate and temperature stable and only changing the concentration of dead
bacteria in the inlet solutions (from 0 to 430 mg/L). Experiments were performed in
sterile conditions, and bacterial growth was prevented by adding NaN3 to the inlet
solutions. Routine culturing of bacteria on the agar plates confirmed the sterility of
experiments.
Samples of outlet solutions were analyzed for major cations and trace elements by
ICP-MS. Results demonstrate a slight decrease in the Si, Ca, and Mg release rates from
basaltic glass with increasing concentration of dead bacteria at pH 4 and 6, but no effect at pH
8 and 10. The Al dissolution rate is lowered by up to one order of magnitude at all four
pH values by the presence of dead bacteria. Comparison of SEM photos of the
basaltic glass before and after experiments show no visible change of the glass
surface. These results suggest that the presence of dead Pseudomonas reactants in
the basaltic formations of Iceland will likely affect negligible the dissolution of
basaltic glass during CO2 sequestration. The main effect of bacterial presence seems
to be 1) the increase of the concentration of DOC that can complex metals and
thus facilitate cation release from the solid phase and/or 2) adsorption of released
metals at the surface of the biomass thus decreasing the overall element export rate. |
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