Characteristics of Acid Precipitation in Kanazawa City

The concentration of nitrogen dioxide in atmosphere at 200-300 sites
in Kanazawa City was measured. At the same time the rain, snow, hail
and dust in atmosphere were sampled and concurrently were observed and
analyzed by using an X-ray powder diffractometer, scanning electron
microscope-energy dispersion diffractometer, and transmission type
electron microscope. In general, the concentration of nitrogen dioxide
is higher in the cities than that in mountainous region and the river
catchment area, and therefore it is influenced by a topography and
wind direction. At an initial stage of rainfall, pH is low and a lot
of acid precipitation is observed. In the dust sampled in the
atmosphere of tunnel and cities, by using an X-ray powder
diffractometer, the quartz, feldspar, clay mineral, gypsum and so
forth were recognized. Based on an observation through the electron
microscope, the sulphur constituents cover a surface of mineral grain
and pollen, and moreover its microshape presents thin film shape or
particle shape, and furthermore frequently is agglomerated. From these
observation results, it is thought that sulfur constituent in
atmosphere is one of the causes for acid rain.