Amino acid diagenesis and adsorption in nearshore anoxic sediments1

Abstract

Amino acid diagenesis and free amino acid adsorption by sediments were studied in cores of nearshore anoxic sediments from Long Island Sound, Florida Bay, and Pettaquamscutt River (Rhode Island). Both organic nitrogen and amino acid content decreased by a factor of about two in the top meter of the sediment. Individual amino acid profiles showed that the acidic and neutral amino acids, despite their different chemical composition, appeared to be equally utilized in both elastic and carbonate sediments. This result differs from the preferential utilization of certain amino acids generally found in deep‐sea sediments. The results of laboratory adsorption experiments suggest that in clay sediments, free amino acids are predominantly adsorbed by the organic matter in the sediment rather than by the clay minerals. However, in the carbonate sediments, the organic matter seems to inhibit the adsorption of free amino acids on the carbonate grains.