IONIC-DIFFUSION COEFFICIENTS AS PREDICTED BY CONDUCTOMETRIC TECHNIQUES

Ion diffusion coefficients were determined for Na, Ca, and Cl in three soils under various moisture regimes. The Nernst-Einstein equation was used in conjunction with bulk soil specific electrical conductivity data to obtain the diffusion coefficient values. The conductivity data were measured in special cells designed to control both solution composition and moisture content. The contribution of both the solution and the surface phases to the total diffusivity of each ion was estimated. The ion diffusion coefficient values were corrected for the nonideality of system.