Regional assessment of dry and wet deposition of reactive nitrogen in East Asia

Satomi Ban1,2, Kazuhide Matsuda1

1 Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan,

2 Japan Environmental Sanitation Center, 11 10-6 Yotsuyakami-cho, Kawasaki 210-0828, Japan


In order to investigate the state of reactive nitrogen deposition in East Asia, we carried out a measurement-based assessment of nitrogen deposition on regional scale in cooperation with the Acid Deposition Monitoring Network in East Asia (EANET). We estimated the dry deposition amounts of HNO3 and NH3 in gas phase, and NO3 and NH4+ in aerosol phase by a modified inferential method using monthly mean inputs of meteorological data. Dry deposition amounts estimated by the modified inferential method well reproduce those estimated by using high time resolution inputs in the case of long-term total dry deposition (e.g. annual deposition). The total (dry and wet) nitrogen depositions at 20 sites in 7 countries in East Asia were in the range of 2.8 – 37 kg N ha-1 year-1, and high total nitrogen deposition amounts over 10 kg N ha-1 year-1 were found in wide areas of the region. The highest amount in each site classification (urban, rural, and remote) was found at Chinese sites. The ratios of dry deposition to total deposition were high in the inland areas due to the low precipitation. And the ratios of reduced nitrogen to total nitrogen deposition were relatively high in southern part of East Asia.