| Research Abstract |
In Japan, acid rain is serious even in the non-industrial regions along the Sea of Japan as well as in the industrial regions facing the Pacific Ocean. In winter, a cold air mass frequently flows from the Siberia to Japan. Deposition rates of sulfate ion from the atmosphere on the coast of the Sea of Japan showed seasonal variations with a large increase in winter. Thus, the increase in deposition rate in winter was attributed to the long-distance transport of sulfur dioxide from the Asian continent. The Ice-Monsters at Mt.Zao and Mt.Asahi, Yamagata Prefecture, and Mt.Hakkoda, Aomori Prefecture, Japan, resulted from a repeated accreation of rime and snow in winter. For implication of the transport of atmospheric contaminants from the Asian continent to Japan, snow and rime samples were collected every winter from 1991 at Mt.Zao, Yamagata Prefecture, Japan. Chemical composition if soluble substances, such as sodium ion, chloride ion, potassium ion and magnesium ion from sea spray salt, non-sea salt sulfate ion and nitrate ion from human activity, non-sea salt calcium from dust along road and ammonium ion from biological activity, and pH,were measured to reveal the atmospheric chemistry. And sulfur isotope ratio of non-sea salt sulfate were measured. Ion concentrations of rime and snow increased with velocity of the northwest winter Siberia monsoon. The pH values were associated with the concentration of non-sea salt sulfate ion and nitrate ion, which means that snow and rime were made acidic with sulfate ion and nitrate ion exhausted from anthropogenic activites. Non-sea salt sulfate ion and nitrate ion ratio of snow, (nss-SO^2-_/NO_3), were larger than unity and were identical to those of rime. It is suggested that non-sea salt sulfate ion and nitrate ion in rime and snow contains sulfur-oxides and nitrogen-oxides from human activity of the Asian continent. Ammonium ion and non-sea salt calcium ion also affected from Asian continent.
|
