Abstract
Core samples of terrestrial sediments at depths of 0∼300 cm at Rikubetsu, Hokkaido, Japan were analyzed for determining the product moment correlation coefficient (r) regarding amino acids, amino sugars, total organic carbon, total sulfur, enzymatic activities and microbial cell density. The abundance of sedimentary organic matter and the density of viable microorganisms were greatest at the surface, and drastically decreased with the depth. However, the D/L ratio of chiral amino acids and non-proteinous amino acids, such as β-alanine and γ-aminobutyric acid, showed a negative correlation with the depth. Hence, racemization reactions and the alteration of dicarboxylic amino acids, aspartic acid and glutamic acid, to β-alanine and γ-aminobutyric acid, respectively, via specific decarboxylation due to diagenesis were observed over the past 10000 years. The vertical distributions of biomarkers are highly consistent with the subterranean microbial activities in the sediment.
