ENVIRONMENTAL FATE OF CHEMICALS IN SOIL

To characterize the environmental fate of chemicals in soil, results o btained in short-term laboratory tests are commonly used, together wit h data on degradation and physical/chemical properties. As long as the chemical is dissolved or in equilibrium with the solid and water phas e of the soil, such result and data are often applicable to describe i ts environmental fate. However, it is becoming increasingly evident th at descriptions of the fate of chemicals in natural environments have to incorporate the effects of different scales in soil structure and n onequilibrium processes for degradation, sorption/desorption, and tran sport. In terms of chemical leaching, outdoor lysimeter experiments co nducted under nonsteady state flow conditions are good alternatives to laboratory tests, as they can simulate field situations quite well. I n this paper, results from a number of leaching studies carried out us ing undisturbed field lysimeters and laboratory studies on degradation kinetics of chemicals are described. Attention has been focused on co mparing these results with what one could expect in terms of environme ntal fate based on 'standard' inherent properties of the chemical, and the problems involved with using such properties as input in environm ental fate models.