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Nitrogen dynamics in the Westerschelde estuary (SW Netherlands) estimated by means of the ecosystem model MOSES
Soetaert, K.; Herman, P.M.J. (1995). Nitrogen dynamics in the Westerschelde estuary (SW Netherlands) estimated by means of the ecosystem model MOSES. Hydrobiologia 311(1-3): 225-246.
Related to:
Soetaert, K.; Herman, P.M.J. (1995). Nitrogen dynamics in the Westerschelde estuary (SW Netherlands) estimated by means of the ecosystem model MOSES, in: Heip, C.H.R. et al. Major biological processes in European tidal estuaries. Developments in Hydrobiology, 110: pp. 225-246, more
Peer reviewed article  

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    Aquatic communities > Plankton > Phytoplankton
    Biochemical phenomena
    Chemical elements > Nonmetals > Atmospheric gases > Nitrogen
    Chemical reactions > Denitrification
    Chemical reactions > Nitrification
    Cycles > Chemical cycles > Geochemical cycle > Biogeochemical cycle > Nutrient cycles > Nitrogen cycle
    Models > Mathematical models
    Monitoring > Environmental monitoring
    Organic matter
    Physics > Mechanics > Kinetics > Chemical kinetics
    Water bodies > Coastal waters > Coastal landforms > Coastal inlets > Estuaries
    ANE, Netherlands, Westerschelde [Marine Regions]
    Marine/Coastal; Brackish water
Author keywords
    Budget; Estuary; Estuarium

Authors  Top 
  • Soetaert, K., more
  • Herman, P.M.J., more

    A tentative nitrogen budget for the Westerschelde (SW Netherlands) is constructed by means of a simulation model with thirteen spatial compartments. Biochemical and chemical processes in the water column are dynamically modeled; fluxes of dissolved constituents across the water-bottom interface are expressed by means of diagenetic equations. The model is calibrated on a large amount of observed variables in the estuary (1980-1986) with relatively fine temporal and spatial detail. Additional constraints are imposed by the stoichiometric coupling of carbon, nitrogen and oxygen flows and the required conservation of mass. The model is able to reproduce rather well the observed distributions of nitrate, ammonium, oxygen and Kjeldahl nitrogen both in time and space. Also, model output of biochemical oxygen demand and total organic carbon falls within observed ranges. By far the most pervasive process in the nitrogen cycle of the estuary is nitrification which mainly takes place in the water column of the upper estuarine part. On average about three times as much nitrate is leaving the estuary at the sea side compared to what enters from the river and from waste discharges. Ammonium on the other hand is consumed much faster (nitrification) than it is regenerated and only about one third of the total import leaves the estuary at the sea side. The budget for detrital nitrogen reveals import from the river, from wastes and from the sea. Phytoplankton uptake of inorganic nitrogen is negligible in the model. About 21% of total nitrogen, 33% of inorganic nitrogen, is removed from the estuary (mainly to the atmosphere through denitrification) and the load of nitrogen net exported to the sea amounts to about 51,000 tonnes per year. Total denitrification in our model is lower than what was estimated in the literature from the late seventies, where a nitrogen removal up to 40-50% of the total inorganic load was reported. Part of the differences could be methodological, but inspection of the nutrient profiles that led to these conclusions show them to be different to the ones used in our study. The oxygen deficient zone has moved upstream since the late seventies, entrailing the zone of denitrification into the riverine part of the Schelde. The nitrification process now starts immediately upon entering the estuary.

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