ABSTRACT

We here report the results of dissolved free amino acid and hydrolyzable amino acid analysis for interstitial water samples collected from two ESOPE long cores (SNAP core 48 and GME core 10). Dissolved free amino acids (DFAA) in the ESOPE samples constitute, in most cases, less than 20% of the total hydrolyzable amino acids in the pore water. Their concentration varies rather systematically with depth in correlation with that of dissolved species such as nitrate, nitrite and manganese for SNAP core 48 and silicate and phosphate for GME core 10. In contrast, the concentration of total hydrolyzable amino acids (THAA) varies with depth by as much as two orders of magnitude. This may be because the organic matter from which the THAA are freed by hydrolysis is strongly associated with sediments and hence has poor mobility through interstitial water. The various individual amino acids show no systematic changes in relative abundance with depth which suggests that the bacteria which decompose organic matter in the deep-sea sedimentary environment do not significantly discriminate among the various amino acids.