HR: 1340h
AN: B33A-1016    [Abstracts]
TI: Biomineralization of Hydromagnesite and its Application in Carbon Dioxide Sequestration
AU: * Power, I
EM: ipower@uwo.ca
AF: The University of Western Ontario, Department of Earth Sciences 1151 Richmond St., London, ON N6A 5B7 Canada
AU: Wilson, S
EM: swilson@eos.ubc.ca
AF: The University of British Columbia, Department of Earth and Ocean Sciences 6339 Stores Rd., Vancouver, BC V6T 1Z4 Canada
AU: Dipple, G
EM: gdipple@eos.ubc.ca
AF: The University of British Columbia, Department of Earth and Ocean Sciences 6339 Stores Rd., Vancouver, BC V6T 1Z4 Canada
AU: Southam, G
EM: gsoutham@uwo.ca
AF: The University of Western Ontario, Department of Earth Sciences 1151 Richmond St., London, ON N6A 5B7 Canada
AB: A collection of highly alkaline wetlands, which exist as part of the hydromagnesite playas near Atlin, British Columbia, contain extensive microbial mats associated with carbonate deposition. X-ray diffraction and scanning electron microscopy has demonstrated that cyanobacteria catalyze the precipitation of hydromagnesite from magnesium-rich waters in this system. In addition, hydromagnesite was also precipitated in laboratory experiments using cyanobacterial enrichments from this field site and filter-sterilized natural waters. Within biofilms dominated by filamentous cyanobacteria, rosettes and flakey globular aggregates of hydromagnesite were precipitated while abiotic controls produced less carbonate in the form of nesquehonite. This precipitation experiment is analogous to the magnesium carbonates that precipitate within the hydromagnesite wetland. Carbonate crusts that form on the water surface are composed primarily of nesquehonite and form due to evaporation. In contrast, the microbial mats that cover the wetland floor are mostly composed of hydromagnesite. The experimental evidence conclusively demonstrates that cyanobacteria precipitate hydromagnesite and have played a significant role in the development of this natural environment. Consequently, Atlin provides a natural model for developing a passive carbon dioxide sequestration process by which ultramafic rock is weathered and re-precipitated as magnesium carbonates with the aid of cyanobacteria in a wetland environment. This biogeochemical process represents an important link between the biosphere and the inorganic carbon pool within the global carbon dioxide budget.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0419 Biomineralization
DE: 0448 Geomicrobiology
SC: Biogeosciences [B]
MN: Fall Meeting 2005