This work studies the release of chemicals into the environment and the processes and pathways by which they reach sites of toxic action within the environment. The properties of chemicals are discussed in the second chapter, and their release into the environment, whether naturally or by industrial processes or accidents, and their subsequent environmental pathways are covered in Chapter three. Having entered the environment a chemical is potentially subject to a wide range of processes which may completely eliminate it from the environment, modify it into another more or less harmful substance, or transfer it to another part of the environment. These processes are considered within soil, aquatic and atmospheric environments. Environmental modelling is a method in predicting the toxic effect of chemicals in the environment and of enabling the assessment of environmental hazards and the appropriate control measure to be defined. Modelling strategies are covered in Chapter four. In presenting methods and principles which can be used in predicting and understanding the fate of chemicals in the environment, this volume should be of interest to all environmental and pollution scientists, laboratory chemists and analysts, and those working in governmental environmental monitoring agencies and industrial personnel concerned with waste disposal.