Hydrocarbons and fatty acids in suspended solid (>0.5μm) of surface water and surface sediment samples from Lake Baikal, Russia were analyzed preliminary to elucidate their features in relation to source materials. The predominance of short-chain n-alkanes (C12-C19) maximizing at n-C17 and n-alkanoic acids maximizing at n-C14 or n-C16 showed that organic matter in surface water is mainly derived from plankton. In contrast, bimodal distributions of short-chain and long-chain (>C19) n-alkanes maximizing at n-C17 and n-C27 and n-alkanoic acids maximizing at n-C14 or n-C16 and between n-C22-n-C28 in the sediments revealed that organic matter is originated both from autochthonous and allochthonous sources. The presence of unresolved complex mixture of hydrocarbons with matured triterpanes and steranes in some suspended solid and surface sediment samples suggests that some parts of surface water and surface sediment are contaminated by petroleum hydrocarbons.
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.