Between May and October 1994 a number of experiments were carried out focusing on the estimation of oxygen and nitrogen fluxes between sediments and near - bottom waters in the region of water outflow from the sewage treatment plant in Swarzewo. It was revealed that sediments play an important role in removal processes of excess inorganic nitrogen when its concentration rapidly increases in the waters. In the investigated area nitrogen is released from sediments into water at the rate of 40 mmol?m-2?h-1. Additionally, the intense production of oxygen by organisms which create microphytobenthos was confirmed. Outside the algae bloom period the primary production in the water in this region was smaller than the produc-tion in the surface layer of the sediments.