Carbohydrates in the sediment of Lake Yunoko - Vertical distribution and implication to their origin.

Abstract

Cellulose, non-cellulose carbohydrates and lignin were investigated in a 30 cm core collected from Lake Yunoko, Nikko, Japan. Organic and mineral analyses indicated that two sediment layers (0-8 cm and 19-25 cm : AL layers) are mainly from soil-derived materials, while the other two layers (9-16 cm and 25-27 cm : AU layers) are composed of a larger amount of autochthonous materials relative to soil derived materials. On the basis of the compositional patterns within non-cellulose carbohydrates which fluctuate in correspondence with the extent of the contribution of soil-derived organic matter relative to lake derived organic matter, it was concluded that rhamnose, fucose and galactose mainly originated from autochthonous organic matter, glucose from soil organic matter, and xylose and arabinose from land higher plant detritus. From these results Gluc/ (Rham+Fuco+ Gala), (Xylo+Arab) / (Rham+Fuco+Gala) and (Gluc+Xylo+Arab) / (Rham+Fuco+Gala) ratios were proposed as useful indices for estimating a relative contribution of allochthonous organic matter to autochthonous organic matter in sediments. Cellulose showed a vertical profile similar to that of lignin, where the abundance is generally higher in AL layers than in AU layers. Both cellulose and lignin were concluded to be useful as indicators of higher plant contribution.