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Recent trends in current and evolving environmental regulatory strategies dictate that EPA will have to rely more heavily on predictive modeling technologies in carrying out the increasingly complex array of exposure and risk assessments necessary in developing scientifically defensible regulations (GPRA Goal 8.1.1). The pressing need for multimedia, multistressor, multipathway assessments, from both the human and ecological perspectives, over broad spatial and temporal scales, places a high priority on the development of broad new modeling tool packages. However, as this modeling capability increases in complexity and scale, so must the inputs. These new models will necessarily require huge arrays of input data, and many of the required inputs are neither available nor easily measured. In response to this need EPA has developed a predictive modeling system SPARC (Sparc Performs Automated Reasoning in Chemistry), which calculates a large number of physical/ chemical parameters from pollutant molecular structure and basic information about the environment (media, temperature, pressure, pH, etc.). The SPARC system has been under development for several years and currently calculates a wide array of physical/chemical reactivity parameters for organic chemicals. Current and future research involves model refinement/extension to additional properties for organic chemicals, and development of this process modeling capability for nutrients and other stressors.
Elucidate and model the underlying processes (physical, chemical, enzymatic, biological) that describe the transport and fate of organic pollutants, nutrients and other stressors in environmental systems. Incorporate these process models in the SPARC system. Construct software interfaces to directly link SPARC to environmental systems models and thus provide not only for model parameterization but for real time upgrades of reactivity parameters during model execution.
Additional EPA Modeling Resources
The process research (see subtasks) involves an integrated effort of scientists and modelers to elucidate and model the underlying processes (physical, chemical, biological) that describe the transport and fate of organic pollutants, nutrients, and other stressors in environmental systems. Phenomenological models are developed for individual physical/ chemical/ microbial/enzymatic processes based on molecular and environmental system descriptors. These models, along with estimation algorithms for reactivity constants, will be incorporated into SPARC. SPARC models will be interfaced directly into MIMS and other multimedia models. In addition, these models will be made available (online INTERNET) and serviced to EPA modeling clients.
Whiteside, T.S., S.H. Hilal, and L.A. Carreira. 2006. Estimation of Phosphate Ester Hydrolysis Rate Constants. I. Alkaline Hydrolysis. QSAR & Combinatorial Science. 25(2):123-133.
Hilal, S. H., L. L. Bornander, and L. A. Carreira. 2005. Hydration Equilibrium Constants of Aldehydes, Ketones and Quinazolines. QSAR & Combinatorial Science. 24(5):631-638.
Hilal, S.H., S.W. Karickhoff, and L.A. Carreira. 2004. Prediction of the Solubility, Activity Coefficient and Liquid/Liquid Partition Coefficient of Organic Compounds. QSAR& Combinatorial Science. 23(9):709-720.
Hilal, S.H., S.W. Karickhoff, L.A. Carreira, and B.P. Shrestha. 2004. Estimation of Carboxylic Acid Ester Hydrolysis Rate Constants. QSAR & Combinatorial Science. 22(9/10):917-925.
Hilal, S.H., S.W. Karickhoff, and L.A. Carreira. 2003. Prediction of Chemical Reactivity Parameters and Physical Properties of Organic Compounds from Molecular Structure Using SPARC (PDF) (158 pp., 2.0 MB, About PDF). U.S. Environmental Protection Agency, Athens, GA. Publication No. EPA/600/R-03/030.
Hilal, S.H., S.W. Karickhoff, and L.A. Carreira. 2003. Prediction of Vapor Pressure, Boiling Point, Heat of Vaporatization and Diffusion Coefficient of Organic Compounds. QSAR & Combinatorial Science. 22(6):565-574.
Hilal, S.H., S.W. Karickhoff, and L.A. Carreira. 2003. Verification and Validation of the SPARC Model (PDF) (44 pp., 1.0 MB, About PDF). U.S. Environmental Protection Agency, Athens, GA. Publication No. EPA/600/R-03/033.