抄録
Investigation conducted in 1992 and 1993 showed that the pH values in the lakes around the top of Mt.Norikura decreased compared with those in 1985. The water in all these lakes had low alkalinity values, low ion content and low pH values. An analysis of the ion balance between rain and water in Lake Tsurugaike revealed that neither ion exchange of H+ for Ca2+ in sediments nor biological reduction of SO42- took place. During the snow melting periods, there was a decrease in the concentrations of major ions in Lake Tsurugaike and an increase in pH values. This indicates that Tsurugaike was strongly influenced by the initial fraction of meltwater containing highly concentrated ions released from snow pack.
