HR: 1340h
AN: B13B-0224    [Abstracts]
TI: Atmospheric Transport and Deposition of Nitrogen Compounds From the Asian Continent Over the East China Sea
AU: * Uematsu, M
EM: uematsu@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo, 164-8639 Japan
AU: Nakamura, T
EM: toku@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo, 164-8639 Japan
AU: Endo, M
EM: makiendo@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo, 164-8639 Japan
AU: Narita, Y
EM: narita@ori.u-tokyo.ac.jp
AF: Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Tokyo, 164-8639 Japan
AB: The growth of economy and population is rapid among in the east Asian countries. Within two decades, emission from east Asia could roughly account for half of the nitrogen released to the atmosphere from all anthropogenic sources worldwide. The Asia/western Pacific region has a unique mixture of aerosols and trace gases because of these distinctive patterns of emissions in combination with the local meteorological conditions affecting the region. Continental outflows can alter bilogical and chemical processes along the coastal Asia and, therefore, modify biogeochemical fluxes and feedbacks that may have serious implications to human health and climate implications. We made atmospheric measurements on board R/V Hakuho Maru over the western North Pacific and the East China Sea from 26 September to 9 October 2002 (the KH02-3 Cruise) in the autumn and from 4 to 20 March 2004 (the KH04-1 Cruise) in the spring. The atmospheric deposition fluxes of nitrogen compounds (ammonium, nitrate, and organic N) to the marine environment were investigated as a part of the IGBP/SOLAS project. Size segregated ambient aerosols (d$<$2.5$\mu$m and d$>$2.5$\mu$m) were collected at every 4-12 hours intervals on a PTFE fiber filter by using a high-volume dichotomous virtual impactor air sampler. Atmospheric average total ammonium concentration over the East China Sea was 2.3 $\mu$g N m$^{-3}$, and that of nitrate was 0.48 $\mu$g N m$^{-3}$. However, $>$90 percent of paticulate ammonium occurred in the fine fraction whereas $>$80 percent of particulate nitrate was in the coarse fraction. By using empirical dry deposition velocities for two size categories, we estimated the ammonium and nitrate dry deposition fluxes over the East China Sea to be 160 Gg N yr$^{-1}$ and 270 Gg N yr$^{-1}$, respectively. Our results clearly show that particle size is critical for different components and flux estimation. The atmospheric inputs of the nitrogen compounds to the East China Sea are found to be comparable to their fluxes of 190 Gg N yr$^{-1}$ and 430 GgN yr$^{-1}$, respectively, by the Changjian River.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 0330 Geochemical cycles
DE: 0345 Pollution--urban and regional (0305)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting