Effect of acid deposition on natural environment in Iriomote Is., the Ryukyus

Abstract

Iriomote Island, the Ryukyus, is easy to receive the effect by the long-distance transportation of acid substances from the Eurasian Continent and Taiwan, since the island is close to these areas. The average pH of the precipitation on the island was 4.7. The values of pH(H₂O) and pH(KCl) were measured in order to examine the effect of the acid deposition on the island. The soil with lower pH(KCl) values showed the smaller ion-exchange capacity. In the watershed which widely distributes siliceous sandstone, the acid buffer capacity by HCO₃^- in river water is small, and the effects of the acid deposition may be remarkable.