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On the freezing-out properties of the lake ice.

1975; Volume: 36; Issue: 4 Linguagem: Inglês

10.3739/rikusui.36.147

1882-4897

Nobutada Nakamoto, Masahiro Ochiai, Tatsuo MIZUTANI, Hidetake Hayashi,

Marine and coastal ecosystems

The study on the freezing-out phenomena of lake water is carried out in two mountain lakes, Lake Suwa and Lake Haruna in the central part of Japan. The reduction rates were measured concerning the following components : dissolved oxygen, carbon dioxide, ions (Cl, Na, Mg, and Ca), dissolved organic carbon, particulate organic carbon and nitrogen, and bacterial number. Substances in solution in the waters freeze out to 80%. The freezing-out of dissolved oxygen and carbon dioxide was also observed. This may account for the significant accumulation of dissolved gases immediately under the ice at the distinct inverse stratification in Lake Suwa. This accumulation was not observed at a volcanic lake of Haruna. In Lake Suwa a trend of the decrease of concentration was observed in the ice from its upper layer to the bottom. In Lake Haruna the opposite tendency was observed. The viable number of bacteria reduces by factor 103 or more in freezing.