Studies on Sphagnum Peat. III. A Quantitative Study on the Carbohydrate Constituents of Sphagnum Mosses and Sphagnum Peat.

Abstract

A qualitative and quantitative investigation of the carbohydrates in two Sphagnum mosses and five samples of Sphagnum peat of different age and degree of huminosity has been performed. The two mosses investigated showed no significant differences. Samples of very different age but with the same degree of physical huminosity were very similar, indicating that the chief changes occur at the top of the bog and/or are determined by the conditions at the start of the humification. The total amount of carbohydrates was about 90 %of the organic material in the mosses and about 65 % and 35 % in peats with a degree of huminosity of 3-4 and 6-7, respectively. Of the constituent sugars, fructose which occurred in the mosses, was completely absent in the peat. Another sugar, which occurs in nature as a furanoside, arabinose, disappeared almost completely during the humification. The uronic acids and galactose decreased faster, while xylose and glucose decreased at about the same rate as the total carbohydrates. Mannose and probably also rhamnose are the most stable components and accumulate during the humification. The polysaccharides in mosses and peat seem to constitute a very complex mixture. The presence of a fructan in the living moss, of a polyuronide (pectin) and a large amount of more complex polysaccharides built up of galactose, xylose, rhamnose and uronic acids is indicated. The glucose, the most important constituent, probably occurs chiefly as cellulose, the presence of which has been demonstrated by other workers. Finally the behaviour of mannose during the humification indicates the presence of a stable mannan. There is no evidence of polysaccharides formed by microorganisms in the peat.