Abstract
The crater lake “Yugama” of Volcano Kusatsu-Shirane, Gumma Prefecture was studied preliminary from the limnological standpoint. It is 260m in length and has an area of 37, 000m2, the maximum depth being 17.7m. One of the extraordinary properties of the lake water is its remarkable acidity, the pH being calculated as low as 0.8. The water (volume calculated as ca. 500, 000m3) contains about 2, 000 tons of sulphuric acid and 2, 500 tons of hydrochloric acid. One litre of water contains 320mg of ferrous ion and 255mg of calcium ion. The surface temperature of water was recorded as high as 28.8°-29.°C (atmospheric 12.3°C) in October and 20.2°C (atmospheric -7.0°C) in December.
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Schedule a callMore From: Japanese Journal of Limnology (Rikusuigaku Zasshi)
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