Relationship between Morphometric Features and Organic Matter Contents of Bottom Sediments at the Deepest Points of Lakes

Based on the analysis of the surface layer (0-3cm) of bottom sediments at the deepest points of 10 lakes in Hokkaido and on the data by other investigators on the organic matter of 10 other Japanese lakes, the relationship between morphometric features and organic matter contents of bottom sediments of lakes was investigated. Concentrations of total nitrogen, organic carbon and ignition loss of the bottom sediments were reversely correlated with the common logarithms of maximum depths in deep (over 30 m in maximum depth) natural lakes. The concentration of organic matter was also related with the ratio of the length of shore line to area except for artificially polluted lakes, man-made lakes, and very large or small lakes. Hence, organic matter of bottom sediments was suggested to be primarily influenced by the morphometric features of lakes. Organic matter of bottom sediments at the deepest points of 20 Japanese lakes consisted of total nitrogen 0.07-0.81%, organic carbon 0.21-7.05% and ignition loss 6-24%.