A MARGINAL FILTER OF THE OCEANS

Marginal filters are formed within the river and sea water mixing zone s in river mouths. Intensive processes of flocculation and coagulation of dissolved (colloidal) and suspended matter, the formation of fresh ferrous and aluminium oxihydrates take place in these zones. The acti on of the sedimentation and sorption parts of the filter is supplement ed with bioassimilation and biofiltration. All these processes result in that 93 - 95% of suspended matter and 20 - 40% of dissolved matter of river discharge (pollution included), on the average for the World rivers, are deposited in the zone. The most important role belongs to the clay sorbent (deposition of 15.2 billion tons per year), the secon d comes for the OM-sorbent (352 million tons of suspended matter and 2 0 - 25 million tons as organic floculii) and the third is Fe-sorbent ( 1.28 million tons of freshly formed and 170 million tons of crystalliz ed oxihydrates). Peculiarities of the Arctic filters in action are con sidered.