Integrated Modeling: Examining the Fate and Transport of Contaminants in Canadian Lakes and Rivers.

With the ever increasing introduction of chemicals to the environment (approx. 4000 new chemicals are registered each day), scientists and program managers are faced with an apparently endless and overwhelming task of examining the possible ecological risks of these new chemicals as well as the existing chemicals in aquatic ecosystems. It is also well recognized that no single model will be capable of dealing with all of the different types of chemicals and the environments that these chemicals are released into. It is therefore necessary to be able to integrate a spectrum of best practice models into a system that allows the user to model the fate and transport of contaminants in an optimized way. This is best done in a decision support system framework that contains not only the core models, but also the data, knowledge, and supplementary tools that are required to run the models and to evaluate their results. ChemSim (Chemical Simulation) has been developed in support of implementing the Canadian Environmental Protection Act (CEPA). The ChemSim modeling system is modular in design with currently seven main components: 1) Drainage Area Ratio Analysis Tool; 2) Discharge Site Analysis Tool; 3) Spatial database; 4) Water Quality Module; 5) Sediment Module; 6) Physical-Chemical Database and 7) Integrated Lakes Modeling Tool. The system has been developed using a well tested decision support system frame work and models. The system has already been used to evaluate over 25,000 chemicals and continues to be developed to allow greater realism of exposure characterization. The paper provides a description of the decision support framework and the system components.