The Oder Estuary - IOW

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Building and putting sewage plants into operation led to a drastic reduction of the influx of nitrogen
and phosphorus by municipalities and industrial factories. The main influxes via rivers are
therefore caused by diffuse sources which provide more than 90 % of the influx of nitrogen and
approximately 80 % of the influx of phosphorus.
The river Oder is mainly responsible for the pollution of the western German part of the Oder
Estuary with nutrients, because it provided approximately 60 % of the influx of nitrogen and 80 %
of the influx of phosphorus in 1995. But also in the river Oder a reduction of the pollution with
phosphorus is noticeable.
As a positive result of the reduced pollution with phosphorus the concentration of phosphorus
dropped considerably and the ration of N:P changed though the effect of the growth of the
phytoplancton in the western Oder Estuary is not visible yet. The reduced pollution with
phosphorus caused only in the river Peene a lower concentration of algae measured as chlorophylla
and an increase of the Secchi depth.
The influxes of heavy metals from the catchment area of Mecklenburg-Vorpommern are low
compared with the influxes from the catchment area of the river Oder. Approximately 85 – 95 % of
the pollution of the western part of the German Oder Estuary with heavy metals was provided via
the river Oder in the mid-nineties. Investigations about the pollution of suspended matters with
heavy metals revealed that there is a high pollution with zinc and cadmium in the Oder Estuary. In
comparison there is only a low contamination with copper, lead, and mercury. Nickel and
chromium don’t accumulate at all.