AMINO-ACID-COMPOSITION OF SEAWATER AND DISSOLVED HUMIC SUBSTANCES IN THE GREENLAND SEA

The amino acid composition of filtered seawater and dissolved organic matter fractionated with XAD-2 resin was measured in samples from the Greenland Sea. Glycine, aspartic acid, glutamic acid, alanine, and ser ine made up ca. 80% of the total dissolved amino acids (TDAA) in the u nfractionated seawater samples and XAD-fractions. Glycine was predomin ant, accounting for 28% of TDAA in seawater, 41 % in the hydrophobic a cid (HbA) fraction and 45% in the hydrophobic neutral (HbN) fraction. TDAA concentrations in the hydrophylic (H1) fraction correlated signif icantly with chlorophyll a, whereas no significant relationship was fo und between chlorophyll and TDAA or the individual amino acid composit ion in HbA and HbN. TDAA values of 150-250 nM are assumed to be presen t as part of refractory compounds throughout the water column. At dept hs of about 1000-1500 m almost 100% of TDAA in seawater is found in th e ''humic'' fractions HbA and HbN. On the average TDAA accounted for c a. 24% of the organic nitrogen content in HbN and about 7% of the nitr ogen in HbA and H1 fractions, respectively.