EXPERIMENTAL AND THEORETICAL ASPECTS OF SOLUTE DIFFUSION IN SPHERICAL AND NONSPHERICAL AGGREGATES

Abstract

We measured diffusion of bromide or 36C1− from cubic and spherical aggregates. These experiments were done with single and mixed sizes of aggreagtes in order to assess (1) whether or not solute diffusion from nonspherical aggregates could be approximated by diffusion in equivalent spheres, and (2) if a mixture of aggregate sizes could be represented by a single weighted-average size. We showed that nonspherical aggregates (cubes) can be represented by equivalent spherical aggregates; the radius of the equivalent sphere was chosen such that the sphere volume was the same as that of the cube. Mixed sizes of spherical or nonspherical aggregates could be represented by a single spherical aggregate whose radius was computed on a volume-weighted basis. This report discusses application of these findings in describing solute transport in aggregated soils.