Effects of Acid Deposition on Metal Materials-Influence of Volcanic Gases from Miyakejima.:Influence of Volcanic Gases from Miyakejima

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To examine the effects on metal material by acid deposition, the measurement of the rainwater components and a leaching test of metal sample plates were conducted in Isogo (urban site: Yokohama City) and Doushi (mountainous site: Yamanashi Prefecture). On the basis of these measurement data, the influence of volcanic gases from Miyakejima on rainwater components and on metal corrosion was evaluated. In Isogo, the annual mean pH value of rainwater collected from September 2000 to August 2001 (after volcanic gases were released) was lower than those collected from September 1999 to August 2000 (before volcanic gases were released). The annual deposition amounts increased 2.1 times for nssSO42- (non sea salt SO42-) and increased 1.9 times for nssCl- (non sea salt Cl-). Corresponding to these, the annual elusion amounts of Cu2+, Pb2+, Zn2+, Fe3+ from the metal plates (bronze, copper, carbon steel) increased 1.7 to 2.6 times. By the dissolution of these metal ions, the weight of the copper plate decreased markedly. In Doushi, the pH value of rainwater was higher than Isogo, and the deposition amount of nssSO42-and the elusion amounts of Cu2+, Pb2+, Zn2+ from the bronze plate were lesser by about 1/2 to 1/3 those of Isogo. But, the tendency before and after volcanic gas evolution was the same as Isogo, indicating that the effect of volcanic gases also reached the mountainous area.
社団法人大気環境学会の論文