The Oder Estuary - IOW

µmol/l
µmol/l
µmol/l
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50
0
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Jahresgang NO3-N im Kleinen Haff
Jahre 1990 - 1999
J F M A M J J A S O N D
Jahresgang NO3-N im Großen Haff
Jahre 1990 - 1999
J F M A M J J A S O N D
Jahresgang NO3-N in der Pommerschen Bucht
Jahre 1990 - 1999
J F M A M J J A S O N D
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median
µmol/l
µmol/l
µmol/l
350
300
250
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50
0
350
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Jahresgang NO3-N im Kleinen Haff
Jahre 1980 - 1989
J F M A M J J A S O N D
Jahresgang NO3-N im Großen Haff
Jahre 1980 - 1989
J F M A M J J A S O N D
Jahresgang NO3-N in der Pommerschen Bucht
Jahre 1980 - 1989
J F M A M J J A S O N D
Figure 5.2: Annual course of Nitrate (µmol/l) in the Kleines Haff (top), the Wielki Zalew (middle)
and the Pomeranian Bay (bottom). The figures refer to the periods 1980 – 1989 (right)
and 1990 – 1999 (left). Data source: State Agency of Environment, Protection of
Nature and Geology Mecklenburg-Vorpommern (LUNG) and West Pomeranian
Voivodeship Inspectorate in Szczecin (WIOS).
Neither the nitrate concentrations in the western lagoon (Kleines Haff), nor concentrations in the
Pomeranian Bay show clear long-term changes during the years 1980 and 2000 (Fig 5.2). The
processes within the systems cause a pronounced variability of the concentrations between and
within years, which cover long-term chances. The reduction of the nitrogen loads in the Oder river
during the two decades causes an obvious reduction in the Wieli Zalew, especially in areas which
are strongly influenced by the Oder river. But even this strong trend of a 50 % reduction of the
nitrate concentrations in the Wieleki Zalew, well visible in the moving averge, is covered by a
strong variability and the highest recoreded concentrations are found only in the 1990’s. The more
detailed comparison of the median nitrate contentrations between the single months in the 1980’s
and the 1990’s reveals, that a certain reduction of the concentrations took place in all three systems
(Fig. 5.3).
25
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median