HR: 10:35h
AN: H42C-02    [Abstracts]
TI: Oxygen Diffusion Measurements in Unsaturated Porous Media on the International Space Station
AU: * Heinse, R
EM: heinse@cc.usu.edu
AF: Utah State University, Dept. of Plants, Soils and Climate, Logan, UT 84322-4820, United States
AU: Jones, S B
EM: scott.jones@usu.edu
AF: Utah State University, Dept. of Plants, Soils and Climate, Logan, UT 84322-4820, United States
AU: Or, D
EM: dani.or@epfl.ch
AF: Ecole Polytechnique Federale de Lausanne, Laboratory of Soil and Environmental Physics, Lausanne, 1015, Switzerland
AU: Topham, T S
EM: Shane.Topham@sdl.usu.edu
AF: Space Dynamics Laboratory, 1695 North Research Parkway, Logan, UT 83431, United States
AU: Podolskiy, I G
EM: igorp@imbp.ru
AF: Institute for Biomedical Problems, Khoroshevskoye Shosse 76 A, Moscow, 123007, Russian Federation
AU: Bingham, G E
EM: Gail.Bingham@sdl.usu.edu
AF: Space Dynamics Laboratory, 1695 North Research Parkway, Logan, UT 83431, United States
AB: Oxygen supply to plant roots in unsaturated porous media is regulated by the amount of water and its distribution pattern. The design of optimal plant growth media must strike a balance between the retention of sufficient amounts of water in pore spaces by capillarity and maintenance of sufficient air-filled pore connectivity for gaseous diffusion. The challenges presented by microgravity conditions aboard spacecraft require novel management approaches to ensure optimal conditions for plant roots. We developed and tested a system for measurement of oxygen diffusion in partially saturated porous media under microgravity conditions. A sealed dual-chamber diffusion cell was constructed and controlled by an automated measurement system capable of controlling porous media water content using a metered pumping system through a porous membrane, and tensiometers to measure matric potentials concurrently. Continuous measurements of oxygen concentrations in the cells were conducted with Galvanic-based sensors providing transient response data for estimating water content-dependent diffusion coefficients. Gas diffusion was modeled as a function of air-filled porosity in mm- sized aggregated particles. Data were collected on the International Space Station between July and September 2007 as part of the ORZS-MIS experimental flight package (http://www.sdl.usu.edu/programs/orzs). Oxygen diffusion measurements in microgravity were compared with earth-based data using triplicate cell measurements in three different porous media. Preliminary results point to enhanced hysteresis in oxygen diffusion dependency on air-filled porosity in microgravity, indicating altered water distribution patterns relative to earth-based measurements. Considering air invasion during drainage, we hypothesize that a critical air-filled pathway forms at lower saturation in microgravity due to the absence of hydrostatic water distribution. A shift in the critical air-filled in microgravity would require adjustment in plant growth system management protocols and possible model development for reliable prediction of microgravity systems response.
DE: 1847 Modeling
DE: 1865 Soils (0486)
DE: 1866 Soil moisture
DE: 1875 Vadose zone
DE: 1899 General or miscellaneous
SC: Hydrology [H]
MN: 2007 Fall Meeting