Project Leadership Team

Project Leader: Lee Bartolotti
Personnel: Paul Fletcher, Yumin Li, Robert Morrison, and Andy Sargent

Objective

In this project, high level computational chemistry methods will be used to investigate thermodynamic and kinetic properties of a number of gas phase Hg reactions in atmospheric chemistry. The list of reactions to be studied include binary gas phase reactions of Hg compounds with the free radicals Cl, ClO, Br, BrO, O3, NO3, NO2, NO, OH, HO2, CH3O2, and CH3O. The list, while not inclusive, contains many of the gas phase reactions that are thought to be important in atmospheric chemistry for predicting the oxidation rates of Hg0 to HgII compounds. The thermodynamic data developed in this work will be used to identify reactions that may be contributing to speciation of mercury in the atmosphere. Rate constants for a number of the more promising gas phase chemical reactions will be estimated using a semi-empirical approach to unimolecular decomposition, variational transition state theory, and Rice-Ramsperger-Kassel-Marcus (RRKM) theory, as appropriate. This information will be used to estimate the atmospheric lifetimes and fates of Hg compounds.

Using quantum mechanical computational techniques, we can safely and accurately calculate the thermodynamic properties of reactions involving mercury. This information will help us examine the relevant reactions which determine the fate of mercury in the atmosphere. Such data is necessary in order to a) design effective remediation processes; b) predict kinetic properties of relevant reactions (as determined from step a); and c) understand how the atmospheric mercury ends up contaminating not just the land and water, but the food chain as well. Computational analyses are well suited to the analysis of the subsequent bioactivity of mercury.

The calculated thermo-chemical, kinetic, and aerosol data will provide important input into the models used in simulations needed for the prediction of the environmental impact of mercury. This project will bring together a diverse group of computational and experimental scientists to investigate the fate of mercury in the atmosphere, land and waterways. The outcome of the project will have a profound impact on the economic development of the coastal plains of Eastern North Carolina. Hopefully, the results of this study will contribute to the development of new technologies to prevent mercury from poisoning the coastal plains and will expedite the removal of existing contaminates.

Task 1: Atmospheric Thermo-Chemistry

  • Construction of numerical and analytic all-electron basis sets for Mercury
  • Identify important gas phase reactions
  • Update literature search
  • Perform geometry optimizations of all reactants and products
  • Perform frequency calculations on all possible reactants and products
  • Build database of results
  • Calculate thermodynamic data and equilibrium constants of all reactions considered
  • Make a web interface and allow access to database on the grid

Task 2: Atmospheric Kinetic Data

  • Modify existing program for calculating reaction thermo-chemistry to follow reaction coordinate
  • Develop RRKM computer program
  • Identify transition states

Task 3: Bioactivity of Mercury

  • Update literature search of bioactivity of mercury
  • Identify possible biological entities that could create methyl mercury, etc.
  • Investigate Hg2+-biomolecule interactions that are related to diseases
  • Develop models

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