HR: 0800h
AN: A11B-0877    [Abstracts]
TI: Partitioning of HNO3 and Particulate Nitrate in Tokyo: Effect of Vertical Mixing
AU: * Morino, Y
EM: morino@atmos.rcast.u-tokyo.ac.jp
AF: Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Tokyo, 153-8904 Japan
AU: Kondo, Y
EM: kondo@atmos.rcast.u-tokyo.ac.jp
AF: Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Tokyo, 153-8904 Japan
AU: Takegawa, N
EM: takegawa@atmos.rcast.u-tokyo.ac.jp
AF: Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Tokyo, 153-8904 Japan
AU: Miyazaki, Y
EM: yuzom@atmos.rcast.u-tokyo.ac.jp
AF: Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Tokyo, 153-8904 Japan
AU: Miyakawa, T
EM: miyakawa@atmos.rcast.u-tokyo.ac.jp
AF: Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Tokyo, 153-8904 Japan
AU: Moteki, N
EM: moteki@atmos.rcast.u-tokyo.ac.jp
AF: Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Tokyo, 153-8904 Japan
AU: Kita, K
EM: kita@env.sci.ibaraki.ac.jp
AF: Department of Environmental Science, Graduate School of Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki, Ibaraki, 310-8512 Japan
AU: Komazaki, Y
EM: komazaki@atmos.rcast.u-tokyo.ac.jp
AF: Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, Tokyo, 153-8904 Japan
AU: Worsnop, D R
EM: worsnop@aerodyne.com
AF: Center for Aerosol and Cloud Chemistry, Aerodyne Research, Inc., Billerica, MA 01821-3976, Billerica, MA 01821 United States
AB: Nitric acid (HNO3) formed via photo-oxidation of NOx is one of the most important acidic gases in urban air. Aerosol nitrate (NO3-), which is one of the major aerosols in urban air, is formed from HNO3 and ammonia (NH3). Ground-based in-situ measurements of gas-phase HNO3 and particulate NO3- were made with high precision (10-20%) and time resolutions of about 1 and 10 minutes, respectively, near the urban center of Tokyo during 2-3 weeks periods in 2003-2004, in order to assess parameters controlling their abundances. HNO3 and NO3- were observed to undergo distinct diurnal and seasonal variations driven mainly by the temporal variations in the HNO3 production rate and HNO3-NO3- partitioning. Higher temperature and lower RH were observed to increase the HNO3/NO3- ratios, as predicted by the thermodynamic theory. Temporal changes in the HNO3-NO3- partitioning controlled the HNO3 and NO3- concentrations more strongly than those in the total nitrate, TN = HNO3 + NO3-. The NO3-/TN ratio showed strong diurnal and seasonal variations, HNO3 becoming a dominant part of TN during midday, except for winter. The partitioning between HNO3 and NO3- was calculated by equilibrium and one-dimensional (1-D) models. By comparing the results from the two models, the vertical mixing was found to effectively shift the partitioning to NO3- at the surface due to transport of air from above, richer in NO3- and poorer in HNO3.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005