CHARACTERIZATION OF FINE PARTICLES BY FLOW-CYTOMETRY IN ESTUARINE ANDCOASTAL ARCTIC WATERS

The chemical and biological nature of suspended pico- (<2 mu m) and na no- (2-10 mu m) particles was studied by flow cytometry in the Lena Ri ver delta and Laptev Sea, Russia, during September 1991. Forward and w ide-angle light scatter, natural fluorescence of phytoplankton, and in duced fluorescence of organic molecules were used to characterise natu ral suspended particles. Organic and inorganic particles were identifi ed by staining with specific fluorochromes: FITC for proteins, Con A-F ITC for glucose/mannose, and PNA for galactose. Living and nonliving o rganic particles were distinguished by analysing simultaneously natura l red fluorescence (chlorophyll) and organic staining. The upper Lena River and its delta were characterised by a high concentration of tota l particles (18.5 +/- 4.9 x 10(5) per cm(3)), mostly inorganic (13.6 /- 5.4 x 10(5) per cm(3)), in the coastal and open waters of the Lapte v Sea, organic particles dominated. Generally, the most important frac tion of small organic particles were nonliving (organic detritus, TEP, and organic coatings) characterised by the presence of proteins and p olysaccharides. The phytoplanktonic cells were characterised by a high fraction of picoplankton (1000-50 000 cells per cm(3)) dominated by S ynechococcus sp. and small picoeukaryotes. (C) 1998 Elsevier Science B .V. All rights reserved.