Diffusion of Zinc in Soils: III. Relation to Zinc Adsorption Isotherms1
- D. D. Warncke and
- S. A. Barber2
The rate of cation diffusion in soil is influenced by the buffering effect of the adsorbed cation on the solution concentration, dCl/dC, i.e., the change in solution zinc concentration with respect to change in the total diffusible soil zinc concentration. This effect was studied with Zn using four silt loam soils having a wide range of initial exchangeable Zn contents and cation exchange capacities (CEC). Zinc adsorption isotherms for these soils had slopes that increased as CEC decreased. The effective zinc diffusion coefficient, De, was measured at five Zn levels on each soil. Measured De, correlated with dCl/dC (r2 = 0.86). Values of De calculated from known values for volumetric moisture content, tortuosity, and dCl/dC were larger than observed De by factors of 5.5 to 18.2. Inclusion of CEC in a multiple regression of observed De with calculated De significantly increased r2 from 0.87 to 0.90. An additional soil factor related to CEC needs to be included to accurately calculate De values for Zn.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © .