MECHANISM OF ACID-NEUTRALIZATION IN 2 JAPANESE WATERSHEDS

In Japan, acidification of terrestrial water has not yet been reported except lakes acidified by volcano or mine. However, acid deposition i n Japan is as much as those in northern Europe and north-eastern U.S.A ., and acidification of terrestrial water may occur in future. In orde r to predict long-term acidification, it is necessary to understand ac id-neutralization mechanism in watershed. Therefore, two experimental watersheds study for geology, hydrology, and water chemistry were cond ucted. On the basis of these data, chemical change in percolation of p recipitation through watersheds and acid-neutralization mechanism are analyzed. The principal results are : (1) Acid deposition is neutraliz ed continuously in percolation of precipitation from ground-surface to aquifer, (2) Chemical weathering of primary minerals plays an importa nt role in the acid-neutralization in the watersheds, and should he qu antified and taken into account in the long-term prediction of acidifi cation.