Amino acid composition of organic matter associated with carbonate and non-carbonate sediments |
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| Authors: | Paul W Carter Richard M Mitterer |
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| Institution: | Program in Geosciences, The University of Texas at Dallas, P.O. Box 688. Richardson, TX 75080, U.S.A. |
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| Abstract: | Amino acids comprise from 15 to 36% by weight of humic substances from carbonate and non-carbonate sediments. Humic and fulvic acids extracted from carbonate sediments are characterized by an amino acid composition consisting primarily of the acidic amino acids, aspartic and glutamic acid. Humic substances from non-carbonate sediments have a distinctly different amino acid composition consisting primarily of glycine and alanine. Amino acid analyses of various molecular weight fractions of fulvic acids extracted from carbonates show that lower molecular weight fractions have appreciably higher relative abundances of the acidic amino acids compared to higher molecular weight fractions. Based on typical values for carboxyl group content in humic substances, acidic amino acids may be a significant contributor of these functional groups. Carbonate surfaces appear to selectively adsorb aspartic acid-enriched organic matter while non-carbonates do not have this property. |
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