Contaminant Transport in Soils Considering Preferential Flowpaths

The presence of preferential flowpaths (PFP) causes high heterogeneity of soil. The complex contaminant transport through highly heterogeneous soil has become a key point on predicting pollution of the soil and groundwater system. In this study, a generalized model of preferential flow paths has been established based on a dual-domain model which reflects contaminant transport and the dynamic transfer between two domains, and quantitatively analyzes the difference between advection-dispersion model (ADM) and dual-domain mass transfer model (DDM) in pore scale. The preferential ratio and scatter number are proposed to reflect the impact of PFP physical parameters. Results show that contaminant mass flux increases significantly with the increase of preferential ratio, specifically when: (1) the preferential ratio is 0.15 and the mass flux is 4.5 times that of homogeneous at 150 a; and (2) the scatter number is 0.22 and the solute flux is 8.5 times that of homogeneous at 150 a. Finally, the impact of saturation change for solute flux was also analyzed in the research.