HR: 0800h
AN: B21A-1010    [Abstracts]
TI: Geochemical and Energetic Variability across Geothermal Systems in Yellowstone National Park (YNP)
AU: * Ackerman, G G
EM: galena_ackerman@hotmail.com
AF: Montana State University, Department of Land Resources and Environmental Sciences 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AU: Macur, R E
EM: rmacur@montana.edu
AF: Montana State University, Department of Land Resources and Environmental Sciences 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AU: Taylor, W P
EM: ptaylor726@aol.com
AF: Montana State University, Department of Land Resources and Environmental Sciences 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AU: Kozubal, M A
EM: markk@montana.edu
AF: Montana State University, Department of Land Resources and Environmental Sciences 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AU: Korf, S
EM: harasfork@hotmail.com
AF: Montana State University, Department of Land Resources and Environmental Sciences 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AU: Inskeep, W P
EM: binskeep@montana.edu
AF: Montana State University, Department of Land Resources and Environmental Sciences 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AB: The physical and chemical characteristics of geothermal outflow channels have been evaluated and correlated with microbial community structure within a variety of geothermal springs in Yellowstone National Park (YNP). Several high-temperature (75-90 C), low to near-neutral pH hot springs in YNP were characterized over a two-year period for a comprehensive understanding of the possible geochemical controls on resident chemolithotrophic microbial populations. Our goal was to analyze and compare YNP geothermal systems in terms of the free energy (ŽGrxn) available from various exergonic oxidation/reduction (redox) reactions. Important electron donors in YNP geothermal systems were measured and include H2, H2S , S0, Fe2+, CH4, and NH4+; terminal electron acceptors of noted importance include O2, NO3-, Fe3+, , S0, SO42- and CO2. Thermodynamic modeling of aqueous chemical species was used to calculate the non-standard state free energy values for a variety of oxidation-reduction reactions potentially important for chemolithotrophic metabolism. Energetic profiles as a function of distance from spring source and temperature were calculated for a series of redox reactions in several YNP springs. Variable temperatures and reactant concentrations across several geothermal springs (pH ranges 2.5-6.8) generally did not significantly change the favorability of many of the reactions considered. These findings imply that observable changes in the distribution of microbial populations are likely linked to physical (e.g. mass transfer, temperature) and biological factors. There are, however, important comparisons to be made among exergonic reactions and presumed metabolisms of resident microbial populations. Both energetic and kinetic considerations will be necessary for understanding which oxidation-reduction reactions provide a competitive metabolic advantage to primary producers in geothermal springs.
DE: 0450 Hydrothermal systems (1034, 3017, 3616, 4832, 8135, 8424)
DE: 0456 Life in extreme environments
DE: 1011 Thermodynamics (0766, 3611, 8411)
SC: Biogeosciences [B]
MN: Fall Meeting 2005