The exceptional Oder Flood in summer 1997 — the fate of nutrients and particulate organic matter in the Baltic SeaDie außergewöhnliche Oderflut im sommer 1997 — der verbleib von nährstoffen und partikulären organischen materials in der Ostsee

The distribution of dissolved inorganic nutrients, particulate organic matter and phytoplankton pigments in the Oder plume was investigated at peak discharge of the Oder River during the exceptional flood event in summer 1997. Mixing diagrams of dissolved inorganic nutrients (NO3-, PO43-, SiO44-) reveal a nearly complete removal of nitrate during the first steps of estuarine mixing, whereas phosphate and silicate were still available over the entire salinity range. In contrast to silicate and phosphate, the nitrate riverine end-member concentration was about 3–4 times lower than during peak discharge in spring. It appears that during the summer flooding event inorganic nitrogen was not as available as in spring due to a stronger dilution effect and the advanced retention of nitrogen by land vegetation within the drainage area in summer. Therefore, algal biomass production in the Pomeranian Bight was most certainly nitrogen limited and significant removal of other dissolved inorganic nutrients by phytoplankton blooming did not occur.