ABSTRACT
An understanding of the occurrence and distribution of pesticides in the atmosphere requires consideration of pesticide sources, transport processes, and mechanisms of transformation and removal from the atmosphere. This chapter presents an overview of these factors and provides a background for the subsequent, more detailed analysis of specific key topics about pesticides in the atmosphere. A uniform distribution is the goal for most pesticide applications. Herbicides commonly are directed at any part of the unwanted plant, whereas insecticides and fungicides ideally are directed at microhabitats within the foliage canopy. Many different types of pesticide carrier formulations exist, and diluents range from water, various solvents, surfactants, and oils, to chalk, clays, ground walnut shells, and so forth. Once in the atmosphere, the residence time of a pesticide depends on how rapidly it is removed by deposition or chemical transformation. In addition to the atmospheric introduction of pesticides sorbed to particles by wind erosion, pesticide vapors can sorb onto suspended particulate matter.
