Einfluss der veraenderten Schadstoffbelastung in der Elbe auf den Sauerstoffhaushalt

The loads on pollutants changed drastically since 1989 after reunification of Germany. Continuous measurements at the station weir Geesthacht, longitudinal profiles with high spatial resolution of the tidal part of the river Elbe and data from the water authorities are used to investigate the consequences on the oxygen budget. In former years oxygen deficiencies are used to investigate the consequences on the oxygen budget. In former years oxygen deficiencies were mainly caused by the degree of nitrification taking place. In former years oxygen deficiencies were mainly caused by the degree of nitrification taking place. Recent time series from monitoring stations and seasonal longitudinal profiles together with a calibrated water quality model (calibrated with time series of chlorophyll-a and nutrient measurements at station weir Geesthacht) shows that nowadays primary production in the middle stretches of the Elbe river mainly controls the oxygen budget. Improved water quality results in algae blooms with concentrations of chlorphyll-a up to 200 #mu#g/l, pH values up to 9 and oxygen oversaturation of 180 %. As the water depth increases at Hamburg Harbour, radiation conditions deteriorate dramatically, biogenic oxygen production decreases accordingly and oxygen consumption by decomposition of algae biomass prevails oxygen production. Estimations of thecarbon content of algae biomass from chlorophyll-a measurements demonstrates that complete mineralization of the algae biomass can quantitatively describe the decrease of oxygenSpecial print from: Vom Wasser, v. 92, p. 37-50(1999)Available from TIB Hannover: RA 3251(99/E/34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman