Carbohydrates in humic and fulvic acids from sediments of Suo sound, Japan

Abstract

Vertical distributions of carbohydrates in humic and fulvic acids isolated from coastal sediments in Suo sound were investigated by gas chromatography and Sephadex gel chromatography. Humate carbohydrates were composed of fulvic acid carbohydrates (70 to 95%). Apparent molecular weight distribution of fulvic acid carbohydrates in vertical direction of sediments was 3·5 to 7·4% below molecular weight (M.W.) 1000, 32 to 42% for M.W. 1000 to 5000, 7·4 to 24% for M.W. 5000 to 10 000, 11·5 to 15·5% for M.W. 10 000 to 25 000, and 28 to 34% for M.W. over 25 000, respectively. Humic acid carbohydrates are present in high molecular weight over 25 000. Fulvic acid carbohydrates decreased with increasing depth. A decrease of humate carbohydrates occurred between the surface layers to 20 cm depth, below 20 cm vertical change of carbohydrates was not observed.