Transport properties of sorbing contaminants in a fractured granite under oxidizing conditions

Abstract

Migration of some sorbing chemical species has been studied in a single rock fracture of 1 m scale in order to understand the transport behavior of contaminants at underground environments. For the tracers, tritium and anions were used as nonsorbing ones and some sorbing cations such as Sr, Co and Cs were used as well. The experimental study was focused on the identification of the retardation and matrix diffusion of the tracer in the fracture. The hydraulic conductivity in the fracture was determined from the pressure differentials between pairs of boreholes. The hydraulic data were used with a variable aperture channel model to characterize the aperture distribution in the fracture. A transport model has been developed to describe the migration of the solutes in the flow field by using a particle tracking method. Results were plotted in the form of elution curves and migration plumes in the fracture. The experimental elution curves have been explored with the transport model which takes into account sorption and diffusion into the rock matrix. This comparison may contribute to further understanding on the heterogeneous flow field and the interactions between rock and chemical species.