HR: 1330h
AN: B12C-0801    [PDF]
TI: Microbial Mediation of Ca-Mg-Carbonates and Mg-Phosphates: Linking the Carbon and Phosphorous Cycles
AU: Vasconcelos, C
EM: cris.vasconcelos@erdw.ethz.ch
AF: Geological Institute ETH - Zurich, Sonneggstr.5, Zurich, ZH 8092 Switzerland
AU: * Roman, M S
EM: monica.sanchez@erdw.ethz.ch
AF: Geological Institute ETH - Zurich, Sonneggstr.5, Zurich, ZH 8092 Switzerland
AU: McKenzie, J A
EM: sediment@erdw.ethz.ch
AF: Geological Institute ETH - Zurich, Sonneggstr.5, Zurich, ZH 8092 Switzerland
AB: An extensive literature exists on the involvement of microbes in mineral precipitation, including in situ studies performed in natural environments where a specific mineral occurs, as well as laboratory experiments. In order to understand the mechanism of biomineralization, bacteria culture experiments must be conducted to evaluate the involvement of microorganisms, which can act as geochemical agents promoting mineral formation by affecting local geochemical conditions. To date, much research on the biomineralization of carbonate minerals has been performed, but little attention has been given to phosphate mineral formation, in spite of its importance in sustaining life and its intrinsic relation with the carbon cycle. We report the results of 25 bacteria culture experiments that were designed to precipitate carbonate and phosphate minerals, using bacteria strains isolated from saline soils in Spain and a hypersaline lagoon, Brejo do Espinho, near Rio de Janeiro, Brazil. In these environments, there is a predominance of carbonate mineral precipitation, such as calcite, high Mg-calcite and dolomite. Of the 25 strains that produced dolomite and calcite, 14 contained, in addition, struvite, while 6 of these produced large amounts of struvite crystals. For any given microorganism, a slight increase in the amount of crystal formation was observed when less calcium acetate was added to the culture media, and a transformation from struvite to monohydrocalcite and dolomite was observed in these experiments. This study provides information to understand the relationship between the phosphorus and carbon cycle during mineral precipitation. Although struvite is not abundant in the geological record, defining its mechanism of precipitation may provide information to better interpret the contribution of microbes in the recycling of phosphorus, as well as the diagenetic processes involving carbonate and phosphate minerals.
DE: 0315 Biosphere/atmosphere interactions
DE: 0330 Geochemical cycles
DE: 0400 Biogeosciences
DE: 0614 Biological effects
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting