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Soil Science Society of America Journal Abstract -

A Closed Tube Method for Measuring Gas Diffusion Coefficients


This article in SSSAJ

  1. Vol. 52 No. 1, p. 17-23
    Received: July 30, 1987

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  1. T. K. Tokunaga*,
  2. L. J. Waldron and
  3. J. Nemson
  1. Lawrence Berkeley Laboratory, Earth Sciences Division, Building 50 E, Berkeley, CA 94720
    Dep. of Plant and Soil Biology, Univ. of California, Berkeley, CA 94720



A transient, closed tube method for measuring both ordinary gas diffusivities and porous media effective diffusivities is presented. The current method is suitable for measuring gas diffusivities in air-dry systems over a range of temperatures. Gas concentrations are continuously monitored in a well-stirred volume of a single end chamber, which is connected to a closed sample chamber during experiments. An analytic solution for this diffusion process is available in which, after a sufficient time, the diffusivity of the sample is obtained from the slope of the logarithm of dimensionless concentration excess versus time. The method was checked by comparing measurements of N2-O2 gas diffusivities at 0, 30, and 60 °C to various previously reported values in the literature. The measured diffusivities fall within the uncertainties of these earlier works.

Contribution of Dep. of Plant and Soil Biology, Univ. of California, Berkeley.

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