The report presents a conceptual model of the movement and disposition of pesticides in the environment. A multi-media model is built up from simple modules representing basic processes and components of air, soil, and water. More specific models are exposited for the atmospheric/terrestrial, freshwater aquatic, and estuaring/marine environments. Ultimately systems analysis and mathematical simulation techniques can be employed to evaluate the fate of a specific chemical in a particular environment. The conceptual model is thus a first step in organizing facts, assumptions, and hypotheses into a graphic and logical arm capable of exploitation in further experimentation of pesticide disposition and effects. A multi-media approach to disposition studies is made explicit even in the absence of a single all-media global model.

"December 1974." U.S. G.P.O. sales statement incorrect in publication. Includes bibliographical references (pages 59-72). Prepared for National Environmental Research Center, Office of Research and Development, U.S. Environmental Protection Agency

A five-year-old Mexican American girl who will not be six until December has a great deal to celebrate when her sister swaps birthdays with her in the summer.