Partitioning and Physical Chemical Properties of PAHs

A review is presented of the physical chemical properties of the polycyclic aromatic hydrocarbons (PAHs), including a discussion of how these properties relate to environmental partition coefficients, for example between air and water, and by sorption from water to solid media such as soils. Complete physical chemical data are given for 15 selected PAHs to illustrate the wide range in properties and the systematic dependence of these properties on molecular structure. From available data on rates of reaction under environmental conditions, half lives of these PAHs in a variety of environmental media are suggested. A series of evaluative Level I and III partitioning calculations is described and presented to illustrate how these properties result in differences in environmental partitioning behavior and persistence, especially a systematic variation in sorption to aerosols and to soils and sediments. It is concluded that assessments of the environmental fate of PAHs require accurate physical chemical and reactivity data over a range of environmental temperatures.