日本海沿岸から脊梁山脈にかけた新雪中の主要化学組成の分布

Abstract

Field work was carried out to investigate the regional characteristics of the concentration of major chemical constituents of snow cover from the coastal area of the Japan Sea to the mountain ranges of central Japan during the winter (January) of 1985. The snow cover in the interior highlands, such as Sugadaira and Takamine, was dry, and therefore the total snow cover retained the concentration of chemical constituents in the snow fall there. In contrast, in the Takada plain, a heavily snow-covered plain of the coastal area in Japan, the lower part held granular snow which contained melt water, and only the upper new snow layers retained the condition of accumulation of chemical constituents. The ratios of concentration of each of the chemical constituents in the new snow suggested that the Na+, Mg2+, and Cl- originated from sea water. The spatial distribution of the concentration of eash chemical constituent in the new snow which accumulated during one series of snowfalls under a winter monsoon situation was claritied. The concentration of chemical constituents originating in sea water decreased farther inland. This distribution was related not only to the distance from the coast but also to topography and the regional differences in cumulus development due to the topography. Excess Ca2+ and SO42- from the expected value originating in sea water were found. In particular, the distribution of excess Ca2+ showed strong regional characteristic, which suggested that there was another source of Ca2+ besides the sea water in the inland areas. Meanwhile, most of the samples contain excess SO42-, which decreases with decreasing amounts of accumulated new snow. The spatial distribution of NO3- concentration in the new snow cover in Sugadaira showed a large variation. The results suggested that the source of the nitrogen oxide was in the neighborhood of the sampling points.