Use of Physicochemical Parameters To Assess the Environmental Fate of Organic Pollutants: The Fugacity Model.

The article focuses on the use of physicochemical parameters to assess the environmental fate of organic pollutants with reference to the Mackay fugacity model. The fugacity of a substance is defined as its tendency to escape from a given phase and has the units of pressure. In dilute systems, the fugacity is linearly related to concentration. The fugacity capacity of a substance in a solid phase can be expressed in terms of the distribution coefficient. For biotic phases the bioconcentration factor is used to evaluate the biota fugacity capacity. The model can be applied to determine the distribution of a pollutant in a multiphase system for which the nature of the phases that are present and their volume must be known. The physicochemical parameters required to estimate the fugacity capacity of pollutants in the different environmental phases are the Henry constant and the octanol-water partition constant. The model allows the use of different partition constants in an easy way, to determine the distribution of a chemical between different phases in equilibrium of an environmental system.