REVIEW OF STRATEGIES FOR MODELING THE ENVIRONMENTAL FATE OF PESTICIDES DISCHARGED INTO RIVERINE SYSTEMS

Pesticides are often produced and stored in large quantities near rive rs posing a potential hazard for the aquatic environment. Accidental i ncidents such as storage facility fires are of major concern as signif icant amounts of pesticide chemicals can enter the nearby riverine sys tem, possibly causing considerable environmental damage, This paper di scusses and reviews the major physical, chemical, and microbiological fate processes of selected herbicides in riverine systems. Glyphosate, paraquat, and diquat herbicides have been selected for discussion as they are widely used and because they degrade in freshwater mainly by well-defined fate processes. The paper concentrates on biodegradation, sorption, and photolysis, the primary fate processes by which these h erbicides degrade. Strategies for mathematically modelling the environ mental fate of pesticides in rivers are reviewed and areas of future w ork identified.