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概要: The pH of snow and rain falling in Niigata City was measured and the anions contained in the snow and rain were also measured. In addition, the influence of such acid snow and rain on the social and natural environment was considered. … The pH values of the melted snow were mostly between 4.6 and 5.4, less than 5.5 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 acid and nitric acid, besides the existence of some salts, e.g., sodium chloride, magnesium chloride, magnesium sulfate. 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 to which Niigata City is facing. The influences of the acidic snowfall and rainfall on structures and sculptures, and on forest and trees were also considered with respect to social and natural conservation. 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 fall probably coming from the large consumption of coal. From some field surveys in forests at 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, almost all of the measured soils were acidified. By analysis of the components leached from the soil with a solution mixture of nitric and sulfuric acids, a relatively small amount of leached phosphate was found along with aluminum, calcium and manganese. A large amount of phosphate might have already been dissolved due to the acidification of the soil. 続きを見る

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