Hydrological Research for Lake Acidification

对新泻县六越地区的湖水进行了化学和同位素分析，以了解湖水pH值的决定因素。同样，对太平洋沿岸的湖泊也进行了调查。实地研究分别于一九九九年十一月及二零零零年五月进行。本研究结果总结如下：这个地区有一些酸性湖泊。但pH值变化较大，有必要继续进行研究2 .集水区pH值较低，地下水流入停留时间较短电导率值受湖泊位置和来源的影响，可用于了解湖泊水与地下水的混合比例pH值与湖水的化学成分之间有一周的相关性日本海一侧的湖泊和太平洋一侧的湖泊在同位素组成上有明显的区别。

Lake water of Joetsu district in Niigata Prefecture have been analyzed for chemical and isotopic compositions in order to know the deciding factors of lake water pH values. Similarly, those of the Pacific coast side lakes have been investigated. The field researches were conducted in November 1999 and May 2000.The results of this study is summarized as follows ;1 There were some acid lakes in this district. But the pH values had a large variation, to be necessary to continue the researches.2 The pH values were low where the residence time of the groundwater inflow was relatively short in teh catchment area.3 The values of electric conductivity was effected by the position and origin of the lakes and was useful to know the mixing ratio of lake water and groundwater.4 There was a week correlation between the pH values and the chemical composition of lake water.5 There was a clear distinction in the isotopic composition between the lakes in the Japan Sea side and those in the Pacific Ocean side.