Introduction

This chapter contains a brief introduction concerning the fate and transport of organic contaminants in soils and groundwater. Physical and chemical properties of some common groundwater contaminants are provided, and non-equilibrium effects in advective solute transport in groundwater due to slow diffusion are discussed. In addition, a general overview is given of processes in the subsurface in which molecular diffusion is important (sorption/desorption kinetics, matrix diffusion, radioactive waste disposal, liners for waste disposal sites, hydrocarbon migration in reservoirs, gas transport in soils, etc.). These processes are discussed in detail in the following chapters.