One of the basic concepts of ocean biogeochemistry is that of an ocean with extremely active boundary zones and separation boundaries of extensive biochemical interactions. The areas of these zones are characterized by a sharp decrease of element migration intensity and consequently the decrease in their concentrations gave the boundaries for the naming of the geochemical barriers (Perelman, 1972). For the purposes of biogeo­ chemistry the most important ones are the boundaries of separation between river-sea, ocean-atmosphere, and water-ground (Lisitzin, 1983). The most complicated of them is the river-sea boundary, where the biogeochemical processes are the most active and complicated (Monin and Romankevich, 1979, 1984). The necessity of studying organic matter in rivers, mouth regions and adjoining sea aquatories has been repeatedly pointed out by v.I. Vernadsky (1934, 1960) who noted both the importance of registration of solid and liquid run-off of rivers, coming into the sea, and "the quality and the character of those elements, which are washed-down into the sea", emphasizing that "wash-down of organic substances into the sea is of great value". The interest in studying organic matter in natural waters, including river and sea waters, has grown considerably over the last 30 years. During this period essential material was collected on the content and composition of organic matter in various types of river waters of the USSR, and this was published in papers by B.A Scopintzev, AD. Semenov, M.V.