Analytical Properties of the Soluble, Metal-complexing Fractions in Sludge-Soil Mixtures: V. Amino Acids, Hexosamines, and Other Carbohydrates in Fulvic Acid
1980
Holtzclaw, Kenneth M. | Schaumberg, Gene D. | LeVesque-Madore, C. S. | Sposito, Garrison | Heick, J. A. | Johnston, Cliff T.
The quantitative distribution of amino acids, hexosamines, and other carbohydrates was determined for three representative, purified fulvic acids extracted from anaerobically-digested sewage sludges. The amino acid content ranged from 5 to 9 wt % in the three fulvic acids and the distribution of acidic, neutral, and basic amino acids generally was similar to that in soil-derived fulvic acids. The principal difference between the two types of fulvic acid was with the S-containing amino acids, which were more abundant in the sludge-derived fulvic acids. The content of galactosamine was very high in the three fulvic acids studied, with the result that the glucosamine/galactosamine ratio was about an order of magnitude lower in these fulvic acids than what is typical for soil-derived fulvic acids. The content of neutral and acidic sugars ranged from 12 to 25 wt % in the fulvic acids, with a distribution of neutral sugars that was similar to what is found typically in natural soil organic matter. Thus the amino acid, hexosamine, and carbohydrate components of sludge-derived fulvic acid may account for up to 50 wt % of this material. The major differences among these components between sludge-derived and soil-derived fulvic acids appear to be related to the high sulfur content of the sludge-derived fulvic acids and their expected high content of anaerobic bacterial residues.
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