Abstract
Specific feature of mono methyl-branched long-chain hydrocarbons, fatty acids and alcohols (anteiso compounds) was found in some moderately acidic (pH=3-5) Japanese freshwater lake sediments. Structural similarities of these compounds suggested that they should have originated from the same kind of organism tolerable to such a restricted habitat. Following investigations revealed that their abundance showed a significant vertical variation in the sediment core of the lakes, where evident pH fluctuations are known in the past. Another work demonstrated that majority of those compounds are contained in aquatic microorganism associated with fine particles suspending in the lake water, whose diameter ranges from 0.6μm to 40μm. Since the anteiso compounds were detected only within the lake system, these findings strongly suggested their possibility as a novel and sensitive biomarker reflecting the pH condition of the lake water.
