HR: 1340h
AN: B33C-1044    [Abstracts]
TI: Existence, Uniqueness, and Limitations of Scaling Laws Relating Mineral Dissolution Rates to Surface Roughness
AU: * Bandstra, J Z
EM: jxb88@psu.edu
AF: Center for Environmental Kinetics Analysis, Pennsylvania State University, EESI 2217 EES Bldg., University Park, PA 16802 United States
AU: Brantley, S L
EM: brantley@essc.psu.edu
AF: Center for Environmental Kinetics Analysis, Pennsylvania State University, EESI 2217 EES Bldg., University Park, PA 16802 United States
AB: Rate treatments for dissolving minerals commonly assume the existence of a steady-state mineral surface where the surface reactivity, roughness, and other characteristics of the surface are temporally invariant. Examples where this assumption is implicit include the use of rate laws that converge to zero-order at large times and the practice of normalizing rate data by a constant surface area. Owing to the slow rates of dissolution reactions, the validity of the steady-state assumption has proven difficult to establish on the basis of laboratory and field observations. In this work we analyze solid dissolution as a Markov process. Using computer simulations of a single-component, 2-D, solid, we find that a simple scaling relationship exists between d(Rate)/dt and d(Roughness)/dt across a broad range of dissolution mechanisms and defect configurations. By expanding the master equation into a set of rate equations for reactive site density, we explore the constraints on this scaling law that may arise in the dissolution of complex multi-component solids.
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
DE: 3265 Stochastic processes (3235, 4468, 4475, 7857)
DE: 4435 Emergent phenomena
SC: Biogeosciences [B]
MN: Fall Meeting 2005