HR: 16:00h
AN: H24C-01    [Abstracts]
TI: Geochemical and Microbiological Controls on Arsenic Cycling in Geothermal Springs of Yellowstone National Park
AU: * Inskeep, W P
EM: binskeep@montana.edu
AF: Department of Land Resources and Environmental Sciences and Thermal Biology Institute, Montana State University, 805 LJ Hall, Bozeman, MT 59717 United States
AU: Macur, R E
EM: rmacur@montana.edu
AF: Department of Land Resources and Environmental Sciences and Thermal Biology Institute, Montana State University, 805 LJ Hall, Bozeman, MT 59717 United States
AB: Many geothermal springs in Yellowstone National Park (YNP) contain high concentrations of arsenic ranging from 1 to as high as 12 mg L-1, and discharge into neighboring streams and rivers resulting in a significant flux of As to regional watersheds such as the Madison River (southwestern Montana). In many cases, the predominant valence of As in geothermal source waters is As(III), but oxidation reactions occurring down gradient of geothermal discharge can result in rapid conversion of As(III) to As(V), with important ramifications for the composition of biomineralized solid phases and the fate of As in these systems. Furthermore, changes in source water chemical composition such as pH and the concentration of dissolved sulfide have a pronounced affect on rates of As(III) oxidation and the microbial populations which mediate As transformation. Several geothermal springs with variable source water composition have been sampled and characterized with respect to aqueous and solid phase geochemistry, and 16S rDNA sequence distribution within the outflow channels. Geochemical attributes of thermal springs are an important determinant controlling the distribution of microorganisms; simultaneously, microbial processes play an important role in dictating aqueous and solid phase chemical speciation within geothermal systems. Functional relationships between As redox cycling and specific microbial populations are being established through both molecular and cultivation approaches.
DE: 1045 Low-temperature geochemistry
DE: 0330 Geochemical cycles
DE: 0400 Biogeosciences
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting