Understanding the Influence of Spatially Varying Retardation Effect on the Solute Transport

Abstract

ABSTRACTA two-dimensional approach to understanding the heterogeneity in retardation effect governing the solute transport was carried out. To express the simplified spatial distribution of retardation effect, this study prepared parallel flat boards packed with two kinds of solid materials, where these materials were not mixed, but arranged as two kinds of the layers in a direction parallel to the flow. The ratio of the width of the constituent layer to the total transport distance was assumed to be one of key parameters describing the solute release profile transported through the media. As a tracer, Eu3+ in HNO3 solution was used, and its breakthrough curve was monitored in the experiments. In order to determine the retardation coefficient of the each layer, the retardation coefficients was obtained from the separate column experiment. Moreover, the permeabilities of both layers were confirmed to be almost identical from the one-dimensional, column experiments. A mathematical model was constructed to express the two-dimensional advection and dispersion of the solute through the media with the distribution of retardation effect. The proposed mathematical model and the experimental results showed good agreements, and indicated that the solute release profile strongly depended on the ratio of the width of the constituent layers to the total transport distance and the standard deviation of the retardation.