MODELING THE GLOBAL DISTRIBUTION OF TOXAPHENE - A DISCUSSION OF FEASIBILITY AND DESIRABILITY

A structure is proposed for mass balance models of chemical fate in which the global environment is divided into nine zones on a latitudinal basis. Each zone consists of air, water, soil and sediment compartments of defined volumes, areas, properties and temperature. By writing and solving the differential mass balance equations for each of the 36 compartments including processes of emission, degrading reactions, advective and intermedia transport, it is possible to deduce concentrations throughout the system as a function of time for a specified discharge scenario. A model of this type is described and illustratively applied to toxaphene. The results are discussed, particularly with a view to determining the parameters which must be better defined to improve the model's accuracy. It is concluded that models of the structure outlined here can play a useful role in understanding and quantifying the global distribution of persistent organochlorine chemicals such as toxaphene, and that they are especially useful for investigating the cold condensation/global fractionation effect.