HR: 1340h
AN: H23D-1621    [Abstracts]
TI: Solute Generation Within Soil Pores Under Variably Saturated Conditions: A Simple Dimensionless Model
AU: * Palucis, M C
EM: mpalucis@berkeley.edu
AF: Department of Earth and Planetary Science UC-Berkeley, 307 McCone Hall #4767, Berkeley, CA 94720-4767, United States
AU: Kirchner, J W
EM: kirchner@berkeley.edu
AF: Department of Earth and Planetary Science UC-Berkeley, 307 McCone Hall #4767, Berkeley, CA 94720-4767, United States
AU: Kirchner, J W
EM: kirchner@berkeley.edu
AF: Swiss Federal Institute for Forest, Snow, and Landscape Research (WSL), Zuercherstrasse 111, Birmensdorf, CH-8903, Switzerland
AB: A major obstacle to understanding the mechanisms controlling weathering fluxes in the soil profile is the spatial variability of pore water chemistry. This chemical heterogeneity presumably reflects the diversity of soil micro- environments at the pore scale. Chemistry at the pore scale reflects each pore's structure, mineralogy, and water residence time. A mechanistic theory of solute chemistry at the scale of pedons, soil profiles, or entire catchments requires an understanding of how soils generate solutes at the pore scale, particularly under partially saturated conditions. We have developed a simple model to study how changes in matric potential alter rates of advection, diffusion and reaction of solutes within interconnected pores. A more realistic pore geometry than the standard capillary bundle model was used so that the role of thin films under laminar flow could be studied. In the model, mineral dissolution occurs along the walls of the pore, under both saturated and partially saturated conditions. The dimensionless Damkohler number (Da), which is the ratio of the reaction rate to the transport rate, and the Peclet number (Pe), which is the ratio of transport by convection to transport by diffusion, were calculated at each matric potential for a given pore size and geometry. These dimensionless numbers help us to identify the dominant mechanisms controlling solute concentrations under different soil moisture conditions.
DE: 1804 Catchment
DE: 1847 Modeling
DE: 1866 Soil moisture
DE: 1875 Vadose zone
DE: 1884 Water supply
SC: Hydrology [H]
MN: 2007 Fall Meeting