The Oder Estuary - IOW

µmol/l
µmol/l
µmol/l
25
20
15
10
5
0
25
20
15
10
7
6
5
4
3
2
1
0
5
0
Jahresgang o-PO4-P im Kleinen Haff
Jahre 1992 - 1999
J F M A M J J A S O N D
Jahresgang o-PO4-P im Großen Haff
Jahre 1992 - 1999
J F M A M J J A S O N D
Jahresgang PO4-P in der Pommerschen Bucht
Jahre 1992 - 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
Jahresgang o-PO4-P im Kleinen Haff
Jahre 1980-1991
Figure 6.2: Annual course of phosphate concentrations (µmol/l) in the Kleines Haff (top), the
Wielki Zalew (middle) and the Pomeranian Bay (bottom). The figures refer to the
periods 1980 – 1991 (right) and 1992 – 1999 (left). Data source: State Agency of
Environment, Protection of Nature and Geology Mecklenburg-Vorpommern
(LUNG) and West Pomeranian Voivodeship Inspectorate in Szczecin (WIOS).
The long-term trend in the lagoon is determined by a slight increase of the phosphorus
concentration until the late 1980’s and pronounced decrease after 1992. The relatively high
phosphorus concentrations in the mid 80’s are a result of wet years, with higher phosphorus loads
via the Oder river (Fig. 6.1). Reduced nutrient loads and dry years are responsible for the ongoing
decrease in the 1990. The high average concentrations in the early 1990’s are caused by
outstanding high concentrations during summer resulting from a phosphorus release by the
sediments, the so-called internal eutrophication. In the lagoon between the 1980’s and the 1990’s
an average reduction of the phosphate concentration of about 50% took place (Fig. 6.3).
µmol/l
µmol/l
µmol/l
25
20
15
10
5
0
25
20
15
10
7
6
5
4
3
2
1
0
5
0
J F M A M J J A S O N D
Jahresgang o-PO4-P im Großen Haff
Jahre 1980 - 1991
J F M A M J J A S O N D
Jahresgang o-PO4-P in der Pommerschen Bucht
Jahre 1980 - 1991
J F M A M J J A S O N D
39
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median