ABSTRACT
This chapter sketches out the movement and retention of organic contaminants in soil, describes the phenomenology in general terms, and describes something about the mechanisms, and then to sound a critique of modeling. The significance of the unsaturated vadose zone arises from its possible function as a protective buffer over the groundwater aquifer. The field-scale, aerial, or spacial variability of basic soil properties, and of the transient conditions of the soil, strongly affects the pattern of migration of an introduced contaminant, depending on the particular time and place of its introduction. The modeling approach allows people, in principle, to develop some statistical and simulation methods to handle several processes and effects simultaneously. The story of modeling the soil environment has produced impressive progress but is not, unfortunately, an uninterrupted parade of triumphs. The crucial question is how good are our models, and that is answerable only by testing with independently obtained data.
