HR: 08:15h
AN: A51A-02    [PDF]
TI: Texas Tech Uuniversity Measurements at BRACE Sydney Site, May 2002
AU: * Dasgupta, P K
EM: sandyd@ttu.edu
AF: Texas Tech University, Dept Chem TTU, Lubbock, TX 79409-1061 United States
AU: Al-Horr, R S
EM: rida.s.al-horr@ttu.edu
AF: Texas Tech University, Dept Chem TTU, Lubbock, TX 79409-1061 United States
AU: Li, J
EM: vepjl@ttacs.ttu.edu
AF: Texas Tech University, Dept Chem TTU, Lubbock, TX 79409-1061 United States
AB: TTU measurements included semi-continuous monitoring of acid gases, gaseous ammonia and total soluble anionic constituents and ammonium in atmospheric particulate matter (with the 50 percent cut off in the collection/measurement system lying above 10 micron mass median aerodynamic diameter) with a 15 min time resolution and formaldehyde, hydrogen peroxide and methyl hydroperoxide measured with 10 min time resolution. Continuous measurements with response times of ~90 s were also made of Hydrogen Peroxide and Formaldehyde on the NOAA Twin Otter Aircraft. Measurements at the Sydney site were made from April 26 through May 31st. Data and findings related to the atmospheric composition of the Tampa Bay Airshed will be presented. The pattern of HCl, particulate nitrate and nitric acid concentrations strongly suggest that at least in part, HCl formation is related to nitrate formation. This postulated reaction of nitric acid on coarse sea salt particles constitutes a dominant pathway for nitrogen deposition. The appearance of gaseous HCl is inversely related to relative humidity; this may be expected as well. The sulfate/ammonium equivalent ratio in equivalents is almost always greater than unity during weekdays suggesting that sulfate is only partially neutralized by ammonium. However, on weekends the same ratio approaches unity. The acidic nature of the fine particles in addition to the abundance of coarse sea salt NaCl also explains the almost exclusive presence of nitrate in the coarse PM fraction. Finally representative patterns of gases and particles will also be presented along with occasional observation of plumes from coal power plants, which passed directly over the Sydney site.
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting