Experiments to determine the transport properties of geological media are often conducted by injecting a tracer into a groundwater flow field established in a radial configuration. These experiments are usually interpreted using either numerical or analytical models based on the advectiondispersion equation. It has recently been shown that significant differences between results are obtained depending on the type of boundary conditions used in the model. Thus, the objective of this study is to investigate the boundary conditions for one-dimensional solute transport in order to determine the most appropriate model for interpreting radial tracer experiments. The investigation is conducted by deriving new analytical solutions that rigorously define the mixing processes in both inlet and outlet reservoirs and at the reservoir-medium boundaries, under conditions of uniform flow. Solutions are obtained for both continuous and discontinuous concentrations at the reservoir-medium interface and for resident and flux-averaged concentrations. A formal mass balance conducted on each of the solutions shows that none can be proved generally superior. An evaluation of the parametric sensitivity of the solutions shows that the distinctions between the continuity conditions and the flux and resident concentrations is substantive, particularly at small Peclet number (the ratio of travel distance over dispersion length). Thus, it was determined that physical modeling is required to resolve the discrepancies between the models. The physical modeling is conducted using columns ranging in diameter from 76 mm to 352 mm and packed with geological material of either small or relatively large dispersivity. Using a conservative tracer, experiments were conducted whereby concentration was measured in reservoirs attached to each end of the column and from within the interior of the column. The results show that the model in which concentration at the boundaries are discontinuous best simulates the physical processes in the vicinity of the boundaries. For this problem, the solutions for resident and flux concentration are identical. The equivalent solution for solute transport in a radially divergent flow field is also derived, although a solution for convergent flow cannot be determined using the solution method. Two tracer experiments were conducted in a horizontally fractured shale using a divergent flow field to demonstrate the use of the new analytical model. The results show that the analytical model will provide an improved estimate of the transport properties of the fracture zone relative to models which do not account for mixing in the source and observation wells.