The Oder Estuary - IOW

Schernewski, G. & T. Dolch (eds.): The Oder Estuary – against the background of the European Water Framework
Directive. Marine Science Reports 57 (2004). ISSN: 0939-396X.
A dynamic box model of the Szczecin Lagoon nutrient cycling
and its first application to the calculation of the nutrient budget
Magdalena Wielgat & Zbigniew Witek
Sea Fisheries Institute, Kollataja 1, 81-332 Gdynia, Poland
Email: wielgat@mir.gdynia.pl, zwitek@mir.gdynia.pl
Summary
In the present paper a dynamic biogeochemical box model of the nutrient cycling within the Oder
River estuary – the Szczecin Lagoon is presented. The model structure is described in detail and
with some general results of the model application to the nutrient budget calculations for the
1980-99 period are given.
1 Introduction
1.1 Introduction
The Szczecin Lagoon (in German – Oder Haff, Stettiner Haff, in Polish – Zalew Szczeciński) is
one of the key elements of the Oder/Odra River estuary (Figure 1.1). Biogeochemical processes
which are part of the functioning of Szczecin Lagoon system influence the quality of the riverine
waters when they finally enter the Baltic Sea. The impact of the Oder waters on the Baltic Sea is
important, since it is the 5 th largest river in terms of water flow in the whole Baltic Sea drainage
area. The Oder River drains over 120,000 km² of densely populated and industrialized catchment,
where arable land covers about 50 % of its total area and
the river discharges high loads of nutrients to the sea. In
this paper we present a dynamic biogeochemical box
model describing main processes contributing to the
nutrient cycling within the estuary with the emphasis on
the main part of the estuary – the Szczecin Lagoon. The
present model represents the approach undertaken by
HUBMORG et al. (2000) to study long-term changes in
biogeochemical processes contributing to the Oder
River nutrient loads modifications in the river estuary.
However, we think that in this approach the seasonal
pattern of nutrient concentrations and phytoplankton
growth is represented better, as compared to the
approach by HUBMORG et al. (2000). The present model
is designed to be used to study nutrient budget of the
Oder estuary. In previous works the nutrient transport
and budget within the western part of the Oder estuary
was modeled by a hydrodynamic model coupled with
nutrient measurements (MEYER et al. 1998; LAMPE
Fig. 1.1 The Oder Estuary.
1999), this was, however, a short term calculation for
the period 1993-95. In the present paper the model