A new mobile-immobile model for reactive solute transport with scale-dependent dispersion
Academic Article
Overview
Research
Identity
Additional Document Info
Other
View All
Overview
abstract
This study proposed a new mobileimmobile model (MIM) to describe reactive solute transport with scaledependent dispersion in heterogeneous porous media. The model was derived from the conventional MIM but assumed the dispersivity to be a linear or exponential function of travel distance. The linear adsorption and the firstorder degradation of solute were also considered in the model. The Laplace transform technique and the de Hoog numerical Laplace inversion method were applied to solve the developed model. Solute breakthrough curves (BTCs) obtained from MIM with scaledependent and constant dispersions were compared, and a constant effective dispersivity was provided to reflect the lumped scaledependent dispersion effect. The effective dispersivity was calculated by arithmetically averaging the distancedependent dispersivity. With this effective dispersivity, MIM could produce similar BTC as that from MIM with scaledependent dispersion in porous media with moderate heterogeneity. The applicability of the proposed new model was tested with concentration data from a 1,250cm long and highly heterogeneous soil column. The simulation results indicated that MIM with constant and linear distancedependent dispersivities were unable to adequately describe the measured BTCs in the column, while MIM with exponential distancedependent dispersivity satisfactorily captured the evolution of BTCs.
