Sources, dynamics and management of phosphorus in a southern Baltic estuary
Today, phosphorus is regarded as the key nutrient for Baltic Sea eutrophication management. Major sources are large rivers like the Oder, Vistula, Daugava in the southern Baltic region. Before entering the Baltic Sea, these rivers discharge their nutrient load into coastal estuaries, bays and lagoons. The quantitative role of these coastal waters, with restricted water exchange, for Baltic Sea management is very important, but not well known. Taking the Oder/Odra estuary as an example we analyze the long-term pollution history and the major sources for phosphorus and calculate a phosphorus budget, with special focus on anoxic phosphorus release from sediments. The budget shows that due to internal eutrophication in July 2000 the lagoon became a major temporary source of phosphorus for the Baltic Sea. A phosphorus emission reduction scenario, taking into account diffuse and point sources in the entire Oder/Odra river basin, is presented. Phosphorus load reductions have only limited effect on the eutrophic state of the lagoon. The lagoon is more sensitive to nitrogen load reductions. Therefore, both elements have to be taken into account in measures to reduce eutrophication.
Download Link