Studies on the features of dissolved constituents in Ukawa River system Part 1 : Relationship between the geological features of river system and dissolved constituents in mountain stream water

摘要

To examine the relationship between the formation process of mountain stream water in the Ukawa River system and geological features, we sampled the atmospheric deposition once a week from February 2009 to February 2010 and also sampled mountain stream and spring water approximately once a month from June to December 2009, and then measured the main dissolved constituents and alkalinity. According to the ratio of the concentration of constituents in mountain stream/spring water to that of atmospheric deposition, we observed that geological features most strongly influence calcium ions (Ca^(2+)). The Ca^(2+) concentration is high in Asoshima River and Shimizudani River mountain streams and Jisaburou Shimizu spring water, where sedimentary Asoshima and Komanoma layers comprised of calcareous sandstone are distributed. On the other hand, the Ca^(2+) concentration is relatively low in water originating from the andesitic Yoneyama Mountain system, such as Haraikawa River and Onme Shimizu spring water on the left side of the Ukawa River.