CHEMFRANCE: A regional level iii fugacity model applied to France

CHEMFRANCE, a computer model allowing to estimate the environmental fate of organic chemicals in France, is presented. This multimedia model is represented by six bulk compartments (i.e., air, surface water, soil, bottom sediment, groundwater, coastal water), and by ten subcompartments. The model employs the fugacity concept and requires information on chemical properties (i.e., molecular weight, aqueous solubility, vapor pressure, n-octanol/water partition coefficient, dissociation constant, melting point, reaction half-lives) and emission rates of the pollutants. The outputs of the model consist of estimated chemical distribution between environmental media, transport and transformation process rates, and steady state concentrations in one of the twelve defined regions of France, or France as a whole, at a chosen season. The nature of the model and its underlying assumptions are described. An illustrative example dealing with the modeling of the environmental fate of isobutylene is presented. Aspects of model validation are discussed and recommendations are made for a proper use of CHEMFRANCE.