ABSTRACT
Most agricultural pesticides, particularly herbicides, are applied during distinct and relatively short seasonal periods. Many reservoirs in the Midwest receive much of their water from surface water sources during the spring runoff period, when concentrations of herbicides in tributary streams are relatively high. Sources in more remote areas, such as forests and roadsides, are much more limited in both area and amount of pesticides applied. Conceptual and mathematical models are used to understand or predict the environmental behavior or fate of pesticides. The use of mathematical models of pesticide environmental fate and transport processes is one alternative to comprehensive monitoring programs. Structure-activity relations have been used to model phase transfer processes in aquatic, atmospheric, and terrestrial environments. The regional multimedia models with the simplest level of complexity only consider how the chemical will distribute itself at equilibrium. Very little research has been done on atmospheric inputs of pesticides to inland surface waters of the United States outside the Great Lakes.
