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EXPOSURE ANALYSIS MODELING SYSTEM (EXAMS): USER MANUAL AND SYSTEM DOCUMENTATION
Citation:
Burns, Lawrence A., D. Cline, AND R. Lassiter. EXPOSURE ANALYSIS MODELING SYSTEM (EXAMS): USER MANUAL AND SYSTEM DOCUMENTATION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-82/023.
Description:
The Exposure Analysis Modeling System (EXAMS) was designed for rapid evaluation of the behavior of synthetic organic chemicals in aquatic ecosystems. From the chemistry of a compound and the relevant transport and physical/chemical characteristics of the ecosystem, EXAMS computes: (1) Exposure: the ultimate (steady-state) expected environmental concentrations (EECs) resulting from a specified pattern of (long-term, time-invariant) chemical loadings, (2) Fate: the distribution of the chemical in the system and the fraction of the loadings consumed by each transport and transformation process, and (3) Persistence: the time required for effective purification of the system (via export/transformation processes) once the chemical loadings cease. EXAMS combines loadings, transport, and transformations into a set of differential equations using the law of conservation of mass as an accounting principal. This law accounts for all of the chemical mass entering and leaving a system as the algebraic sum of external loadings, transport processes that export the compound from the system, and transformation processes that convert the parent compound to daughter products.