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A REGIONAL ATMOSPHERIC FATE AND TRANSPORT MODEL FOR ATRAZINE, PART I: DEVELOPMENT AND IMPLEMENTATION
Citation:
Cooter, E J. AND W T. Hutzell. A REGIONAL ATMOSPHERIC FATE AND TRANSPORT MODEL FOR ATRAZINE, PART I: DEVELOPMENT AND IMPLEMENTATION. ENVIRONMENTAL SCIENCE & TECHNOLOGY 36(21):4091-4098, (2002).
Impact/Purpose:
The goal of this research is to develop and test appropriate chemical and physical mechanisms for use in EPA's Models-3 chemical/transport models. These models will be addressing issues of tropospheric photochemistry, fine particles, toxic and semi-volatile substances, and acid deposition. As such, scientifically credible mechanisms for atmospheric gas- and aqueous-phase chemistry as well as heterogeneous chemistry, applicable to the particular pollutant regimes must be included in Models-3.
Description:
The Community Multiscale Air Quality (CMAQ) modeling system is adapted to simulate the regional transport and fate of atrazine, one of the most widely used herbicides in the United States. Model chemistry and deposition are modified, and a gas-to-particle partitioning algorithm is added to accommodate semivolatile behavior. The partitioning algorithm depends on humidity, temperature, and particulate matter concentration and composition. Results indicate that gaseous atrazine will usually dominate warm season atmospheric concentrations, but particulate form can surpass gas forms when atmospheric humidity is high (>70%) and less-acidic (pH > 2.5) aqueous aerosol component is present. Implementation of the modified CMAQ for atrazine is illustrated, and, within the limits of our current understanding, preliminary transport and fate patterns appear to be reasonable. This research represents one of the first attempts to include a gas-to-particulate matter partitioning mechanism in an Eulerian grid-model.
The information reported here has been funded in part under an Interagency Agreement from the U.S. Environmental Protection Agency, Great Lakes National Program Office (DW13947769-01). It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorse ment or recommendation for use.