ABSTRACT
This chapter provides overviews of several multimedia models that are illustrative of the variety of applications that exist. The scope of application of the strategies outlined for Level I–IV calculations is very broad in terms of specific environmental fate questions. Air–water exchange process calculations are useful when estimating chemical loss from treatment lagoons, ponds, and lakes; for estimating deposition rates of atmospheric contaminants; and for interpreting observed air and water concentrations to establish the direction and rate of transfer. Chemicals are frequently encountered in surface soils as a result of deliberate application of agrochemicals and sewage sludge, and by inadvertent spillage and leakage. The Soil model is available from the Canadian Environmental Modelling Centre website as a spreadsheet model, similar to the AirWater model. Chemical persistence leads to one of the most vexing international environmental issues, that of long-range transport to areas remote from the chemical source.
