PHOTOSYNTHETIC PIGMENTS IN THE SURFACE-LAYER OF THE ATLANTIC-OCEAN BETWEEN 50-DEGREES-N AND 60-DEGREES-S RELATED TO THE BIOPRODUCT1ON OF ORGANOHALOGENS AND TO THE INCREASE IN UV-RADIATION

The concentration of particulate chlorophyll a in seawater as well as the pattern of other photosynthetic pigments from various sampling sit es and depths in the phototropic zone of the Atlantic Ocean have been determined. The samples were taken and analyzed during the cruise of t he research vessel ''Polarstern'' from Bremerhaven, Germany to Cape To wn, South Africa (cruise leg: ANT XI/1; 18 october 1993 - 27 november 1993). Ship-side pumps and a 12-bottle--rosette-sampler provided seawa ter containing plankton, which was sampled by filtration. The photosyn thetic pigments were extracted with acetone and ultrasonication. The c oncentrated extract was analyzed by liquid chromatography, using an an alytical HPLC-column with Polyol (Si100, 5 mu m) as the stationary pha se in normal-phase mode. The entire procedure takes about 150 minutes. The concentrations of particulate chlorophyll a of the surface layer were found to vary between 0.03 mu g/L and 0.6 mu g/L. Samples from 30 - 80 m depth gave higher values up to 1.22 mu g/L. The pattern of the photosynthetic pigments varies depending on sampling site, depth, and day-time. The method also provides a sensitive tool to register any s ignificant changes in the total pattern of the photosynthetic pigments of the phytoplankton due to an increased UV radiation caused by the t hinning of the ozon layer.