The Oder Estuary - IOW

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ext_water dissolved subst. = 0.51 + 0.08 ≈ 0.6 m -1
ext_phytopl. = 0.09 m 3 mmol -1 N in phytoplankton = 0.045 m 3 mg -1 Chl_a (KIRK 1994)
ext_Ndet = 0.03 m 3 mmol -1 N (MASKE & HAARDT 1987)
2.3.6 Phytoplankton mortality
0.20
0.15
0.10
0.05
0.00
Jan Feb Apr Jun Aug Oct Dec
Fig. 2.4 Mortality rate values (ceoff_mort)
over the course of a year.
2.3.7 Sedimentation
The range of values of the phytoplankton
mortality coefficient varies from about 0.02
do 0.18 per day depending on the season
(Figure 2.4). Higher values used in the second
half of the vegetation season represent much
higher phytoplankton mortality due to
zooplankton grazing.
Mortality=coeff_mort x PHYTOPLANKTON
Phytoplankton and detritus sedimentation ratios equal in the model. It results from the assumption
that settling of the particles in a shallow water body depends more on the water mixing conditions
rather than the size of particles. Thus the settling rate for all particles should be similar and reflect
difference between the loss rate of material and the resuspension.
Sedimentation Phytoplankton = coeff_sedim x PHYTOPLANKTON
Sedimentation Ndet = coeff_sedim x Ndet
Sedimentation Pdet = coeff_sedim x Pdet
coeff_sedim = 0.05 day -1 . In the Szczecin Lagoon of a depth 3.8 m it means average “net”
sedimentations at a rate of 0.2 m day -1 .
2.3.8 Mineralization of nutrients
Mineralization of nutrients in organic matter (detritus) in the water column and in the sediment
depends on temperature in the same way. The Q10 value for the temperature coefficient
equals 3.11.
temp_coeff_min = temp_coeff_min_sed = 1.12
Mineralization of nutrients in organic matter takes place at the same rate for nitrogen and
phosphorus. There are, however, two different mineralization rates used in the model: one for
mineralization in the water column (coeff_min) and one for mineralization in the sediment
(coeff_min_sed). The mineralization rate in water is ten times higher. It reflect, apart from bacterial