抄録
Lipid compounds were analyzed in a 14cm length of core sediment collected from the south basin of Lake Kussharo-ko, Hokkaido Japan. The long-chain (>C23) anteiso compound series (alkanes, fatty acids and alcohols) were detected in every section of the core, which had been shown to be unique in the moderately acidified (pH=3-5) freshwater lake sediments. However, abundances of the anteiso compounds varied significantly, showing maxima at 0-1 and 4-5cm sections. Increament of the relative abundance represented by the anteiso/normal abundance ratios was in well accordance with the decrease of the odd-even carbon number preference of straight-chain species. It suggested a variable contribution from lipids of certain acid-tolerant bacteria and therefore a significant fluctuation in the pH condition of the lake water, which should be influenced by the inflow of hot spring waters evolving in the caldera basin.
