Multimedia Environmental Distribution of Toxics (Mend-Tox). I: Hybrid Compartmental-Spatial Modeling Framework

An integrated hybrid spatial-compartmental modeling approach is presented for analyzing the dynamic distribution of chemicals in the multimedia environment. Information obtained from such analysis-which includes temporal chemical concentration profiles in various media, mass distribution, and intermedia chemical mass fluxes-can be used for subsequent exposure and risk analyses. The hybrid modeling framework consists of both uniform (air, water, suspended solids, vegetation, biota, suspended solids, and atmospheric aerosols) and nonuniform (soil and sediment) environmental compartments. The interactive system of model equations for the uniform compartments (ordinary differential equations) and nonuniform compartments (1D partial differential equations) must be solved simultaneously to ensure conservation of mass. In order for the approach to be of practical use, parameter input could be minimized through the use of theoretical or empirical description of intermedia transfer processes and estimation methods for associated intermedia transport parameters. Environmental problems are complex, and there are numerous possible multimedia analysis scenarios that may be of interest. Therefore, efficient and user-friendly implementations of such models are essential if multimedia analysis is to become a standard environmental tool.