HR: 08:40h
AN: B31F-03    [Abstracts]
TI: The Role of Mobile Surface Ions in Nanomaterial Formation
AU: * Kendall, T A
EM: treavok@clemson.edu
AF: Clemson University, Department of Environmental Engineering and Earth Sciences, Clemson, SC 29634, United States
AU: Martin, S T
EM: smartin@seas.harvard.edu
AF: Harvard University, School of Engineering and Applied Science 29 Oxford St., Cambridge, MA 02138, United States
AB: Biogenic and abiotic nanomaterial formation alters the electrical layout of mineral surfaces. Complex dielectric and surface diffusional regimes that affect water sorption, metal co-precipitation, and possibly cell attachment are created. Polarization force microscopy measurements reveal the importance of mobile, surface associated ions in nanomaterial formation, particularly in subaerial conditions. Mass and charge transport between nanostructures can occur via two-dimensional diffusion of surface ions within mono- to multi-layer water. Further, nanostructure stability depends on epitaxy with the underlying substrate. On calcite under humid air, we observe the formation of a 1 to 1.5 nm thick, hydrated calcium carbonate film. This nanophase, which is typically protein- stabilized as an intermediate within biomineralization schema, is instead stabilized by the calcite 104 surface. Moreover, nanostructure dissolution on rhodochrosite is initiated by the accumulation of hydrated, edge- associated ions, most likely representing partially mobilized, positively-charged film material. We connect these molecular-level observations to large-scale, biogeophysical measurements that hold promise of remotely sensing bacteria in the subsurface (e.g., induced polarization (IP)). Here, mobile surface ion diffusion at the cell- mineral interface and biogenic nanomaterial formation are identified as key contributors to the poorly understood IP signature of bacteria in porous media.
DE: 0416 Biogeophysics
DE: 0419 Biomineralization
DE: 0461 Metals
DE: 0463 Microbe/mineral interactions
DE: 3947 Surfaces and interfaces
SC: Biogeosciences [B]
MN: 2007 Fall Meeting