| Popis: |
[1] Rainwater and aerosol samples were collected from a coastal urban area (Qingdao) and remote islands (Qianliyan and Shengsi) and along cruise tracks in the Yellow Sea and East China Sea from 1997 to 2005. The samples were analyzed for nitrogen species (NO3−, NO2−, NH4+, and organic nitrogen) and other important elements. The nitrogen species concentrations showed considerable temporal and spatial variations for wet as well as dry atmospheric depositions. In addition, there was a dramatic reduction in the influence of anthropogenic emissions on nitrogen species with increasing distance from coastal urban stations to remote areas across the Yellow Sea and East China Sea. The monsoon climate of East Asia also had prominent effects on the atmospheric composition of nitrogen, with higher loadings in northerly (i.e., winter) than southerly (i.e., summer) monsoon periods, owing to strong emissions from the East Asian landmass. Dust storms in spring dramatically reduced the periodically high concentrations of atmospheric pollutants (e.g., nitrogen species) across the NW Pacific Ocean, but this was accompanied by a twofold-to-fourfold increase in the temporal deposition flux, which showed broad spatial dimensions. Finally, our study identified a strong gradient of wet as well as dry nitrogen deposition fluxes from East Asia to the interior of the North Pacific Ocean. The gradient reflected changes in emission sources and chemical reactions (e.g., forming secondary aerosols), rainfall and scavenging, and change in air mass trajectory. |
Plný text