The Oder Estuary - IOW

104
nutrient concentrations by monthly average water discharge (Figure 2.2). There is no time lag
between water entering and leaving the lagoon.
tons N/year
tons P/year
120000
100000
80000
60000
40000
20000
0
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
1980
1980
1981
1981
1982
1982
1983
1983
1984
1984
1985
1985
1986
1986
1987
1987
1988
1988
1989
1989
1990
Nutrient loads form the Oder River and the immediate drainage of the Lagoon were taken into
account as forcing function in the model. Since measurements for the Oder River are carried out at
cross-sections located more than 60 km up the point where the river waters enter the Szczecin
Lagoon it, leaves out about 12,000 km 2 of the immediate drainage basin on both parts of the
Lagoon with some important point sources of pollution such as the city of Szczecin with population
over 400,000 ind., or industrial enterprises such as Police fertilizers factory which, in the 1980’s,
was seen as a significant point source of phosphorus (WIELGAT 2002). Estimated total loads of
nutrients from the immediate Grosses Haff drainage area used in the model amounted to about
6,000 tons of nitrogen and about 700 tons of phosphorus in the 1980-89 period and about 6,000
tons of nitrogen and about 400 tons of phosphorus for the 1990-99 period. For the Kleines Haff the
nitrogen loads amounted to about 6,000 tons and from 200 tons of phosphorus for the 1980-89 to
about 50 tons phosphorus on average for the 1990-99 period (WIELGAT 2002; 2003).
2.2.4 Water exchange between the Szczecin Lagoon and the Baltic Sea and the
nutrient loads entering from the sea
1990
1991
Inflow of the sea water is calculated on the basis of salinity content in Szczecin Lagoon water. It is
assumed that salinity as a conservative factor reflects share of the sea water in overall water budget
of the Lagoon. Salinity data form WIOS and LUNG were used. All chlorinity values were
DIN
Ntot
Water flow
1991
PO4
Ptot
1992
1993
Water flow
Fig. 2.2 Nutrient loads from the Oder River 1980-99 measured at the Krajnik Dolny crosssection
(data by WIOS in Szczecin) and annual water outflow measured at Gozdowice
cross-section (IMWM 1980-83; 1987-2000).
1992
1993
1994
1994
1995
1995
1996
1996
1997
1997
1998
1998
1999
1999
800
700
600
500
400
300
200
100
0
800
700
600
500
400
300
200
100
0
m3/s
m3/s