Changes in Natural Microbial Communities in Basalts Exposed to Geological Carbon Sequestration Conditions
Abstract
One proposed solution to increasing concentrations of CO2 in the atmosphere is geologic sequestration of CO2 in the deep subsurface. Microorganisms are numerous in the subsurface and may play a pivotal role in the sequestration of CO2. The Wallula pilot well in Eastern Washington state provided the opportunity to investigate how a native microbial community will respond to the injection of supercritical CO2 (scCO2) into basalt. Formation water from the depth of planned CO2 sequestration was used to inoculate basalt cores contained in pressure vessels maintained at the temperature (35°C) and pressure (82.7 bar) of the sequestration interval and then the cores were exposed to scCO2 for as long as 146 days. Petrographic and scanning electron microscopy (SEM) analyses revealed the presence of thick ferro-magnesium carbonate lining the vugs in basalts exposed to scCO2 and microorganisms. SEM analysis also demonstrated the presence of possible biofilms within the fissures of the basalt core. Molecular analyses showed that microbes survived the scCO2 exposure and that cell numbers slowly increased over time after the initial exposure to scCO2. Microbial community analysis revealed a shift in the community from being initially dominated by Proteobacteria to being dominated by Firmicutes, particularly the genus Alkaliphilus. These results indicate that microbes may assist in sealing fractures in geologic media and suggest the importance of subsurface monitoring of native microbial communities in formation waters exposed to CO2 during carbon sequestration.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.B43B0398C
- Keywords:
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- 0428 BIOGEOSCIENCES / Carbon cycling;
- 0448 BIOGEOSCIENCES / Geomicrobiology;
- 0456 BIOGEOSCIENCES / Life in extreme environments;
- 0465 BIOGEOSCIENCES / Microbiology: ecology;
- physiology and genomics