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Fugacity Modeling

  1. Thomas M. Cahill,
  2. Donald Mackay

Published Online: 15 APR 2003

DOI: 10.1002/047126363X.agr087

Encyclopedia of Agrochemicals

Encyclopedia of Agrochemicals

How to Cite

Cahill, T. M. and Mackay, D. 2003. Fugacity Modeling. Encyclopedia of Agrochemicals. .

Author Information

  1. Canadian Environmental Modelling Centre, Trent University, Peterborough, Ontario, Canada

Publication History

  1. Published Online: 15 APR 2003


The environmental fate of applied agrochemicals can be estimated with either conventional concentration-based or fugacity models. Although both types of models can predict the fate of chemicals, the fugacity models have several inherent advantages. Fugacity models express the chemical potential in diverse media in common units of pressure, and so the chemical equilibrium among media is expressed directly. This is particularly valuable when assessing the migration of the chemical among diverse media such as air, water, soil solids, plants, and animals. Chemical transport and transformation processes, such as advection, diffusion, and reaction, are quantified using D-values, which share identical units despite describing very different processes. This uniformity aids in identifying the important processes governing chemical fate in the environment, and it simplifies the formulation and interpretation of the modeling equations. Modeling and assessing the fate of agrochemicals in terms of fugacity as well as concentrations can contribute to a fuller understanding of agrochemical behavior. This article presents a brief conceptual overview of the fugacity framework, describes situations using malathion as an example, and provides references for further consultations.


  • fugacity;
  • multimedia model;
  • environmental fate;
  • partitioning;
  • malathion