AMINO-ACIDS IN THE SEDIMENTS AND INTERSTITIAL WATERS FROM ODP HOLE-677B AND HOLE-678B IN THE PANAMA BASIN

Biogenic siliceous and calcareous sediments were drilled at sites 677 and 678 on the flank of Costa Rica Rift in the Panama basin. We analys ed DCAA (dissolved combined amino acids) and DFAA (dissolved free amin o acids) in the interstitial waters as well as THAA (total hydrolyzabl e amino acids) in the sediments in order to evaluate the relationship between THAA, DCAA and DFAA. Comparison of the THAA in the sediments a nd in marine settling particulate matter (Ittekkot et al., 1984 b) sho wed that the concentration of non-protein amino acids (e. g., beta-ala nine, gamma-aminobutyric acid, and ornithine) was much higher in the s ediments and that the neutral amino acid fraction was depleted in the sediments. These results, together with the organic carbon profile, in dicated that the production of non-protein amino acids occurred mainly at shallow depth but still continued through the sedimentary column, at a slow rate and that the neutral amino acid fraction was more liabl e to decomposition than the acidic and basic amino acid fractions. The positive correlation between total DCAA and the DFAA and the weak cor relation of the total amino acid concentrations between the interstiti al waters and sediments suggested that biological and/or chemical reac tion rates between the DCAA and the DFAA were much higher than the dig estion and/or transformation rates of the THAA in the sediments. The h igher ratio of neutral to acidic amino acid fractions in the DFAA than in the DCAA was attributed mainly to reaction or adsorption with carb onates and partly to the contribution of decomposed products of the ne utral fraction in the THAA of the sediments.