Concentrations of amino acids in hydrothermal sediments collected from the Izena and Yoron Cauldrons, Okinawa Trough

The distribution and concentration of hydrolyzable amino acids and acid-extractable free amino acids in seafloor sediments collected from the Izena and Yoron Cauldrons hydrothermal systems, Okinawa Trough, were determined. The total hydrolyzable amino acid (THAA) concentrations were between 2.95 and 20.58 μmol/g, and Gly was the most abundant amino acid, followed by Asp, Ser, Ala, Val, and Phe. The high concentration of Gly suggests that the samples were hydrothermally altered. Small amounts of D-Asp, D-Glu and D-Ala were observed in the hydrolyzable fraction of sediments. The D/L ratios were