EFFECT OF ACID SNOW AND ACID RAIN ON THE SOILS AND OTHERS IN NIIGATA PREFECTURE

The pH of snow and rain falling mostly in Niigata City was measured. The anions contained in the snow and rain were also measured. In addition, the influence of such acid snow and rain on the soil, structures and sculptures, and forest and trees was also considered with respect to social and natural conservation. The pH values of the melted snow were mostly between 4.17 and 6.3. However, most of these values were less than 5.6, the value used to identify acid snow and acid rain. The pH values of the rain, meanwhile, were slightly greater than that of the acid snow. The acids, which caused the pH to decrease, were estimated to be sulfuric and nitric. The concentrations of such salts were larger than those of the acids. The snow and rain falling in Niigata City were strongly influenced by the sea breeze containing the salts coming from the Japan Sea which Niigata City faces. From observations of construction materials, some buildings damaged by the acidic snowfall and rainfall have been found in and around Niigata Prefecture. Also, in Eastern Europe, many damaged structures and sculptures were easily found due to the acidic rain and snow fall probably coming from the large consumption of coal. From some field surveys in the forests of Niigata Prefecture, few withered trees due to acid snow and rain have been found, although the possibility such damaged trees should exist. One source of this possibility is the acidified soil. From our measurement of soil pH, 36% of the measured soils were acidified. By analysis of the components leached from the soil with a mixed solution of nitric and sulfuric acids, a relatively small amount of leached phosphate was found along with calcium and manganese