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This article in SSSAJ

  1. Vol. 50 No. 6, p. 1419-1424
    Received: Oct 28, 1985

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The Effect of Adsorption on Sulfate Leaching1

  1. N. S. Bolan,
  2. D. R. Scotter,
  3. J. K. Syers and
  4. R. W. Tillman2



Movement of sulfate (S) through repacked columns of soil with high and low S adsorption capacity was studied in the laboratory. Differences in movement could be explained by the shape of adsorption isotherms which were determined from batch-type experiments. 35S was found to be a suitable tracer to study the movement of applied 35S. For step-function changes between 0, 3.12, and 6.24 mol m−3 in the concentration of the applied S solution, different breakthrough curves (BTC) were found for the rising and falling limbs. Also the higher the concentration of S in the applied solution, the earlier the added S appeared in the effluent. The BTC obtained agreed well with those calculated from numerical solution of the dispersion-convection equation, assuming a Freundlich adsorption isotherm and instantaneous reversible adsorption. However, after leaching of a pulse of S added to the surface soil, the observed S distributions in soil columns were not well described by theory. The discrepancies were largest when the soil containing the added pulse of S was incubated prior to leaching. Possible reasons for this lack of agreement are discussed.

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