The Terrestrial-Marine Interface: Modelling Nitrogen Transformations During its Transfer Through the Scheldt River System and its Estuarine Zone

Billen, Gilles; Lancelot, Christiane; Debecker, Eliane; Servais, Pierre

doi:10.1016/s0422-9894(08)71058-4

Cited by 10 publications

(6 citation statements)

References 13 publications

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“…SEITZIN- GER, 1988). Highly variable percentage reductions have been obtained for streams and rivers, ranging from less than 2 % in shallow Danish streams (JEPPESEN er al., 1987;CHRISTENSEN and SBRENSEN, 1988) to more than 70% in slow-running and heavily organic loaded rivers in Central Europe (BILLEN et al, 1986). Similar high ranges have been found when considering all sizes and eutrophication levels of lakes and estuaries (8 to 81 %, SEITZINGER, 1988).…”

Section: Introductionmentioning

confidence: 56%

Nitrogen Loss and Denitrification as Studied in Relation to Reductions in Nitrogen Loading in a Shallow, Hypertrophic Lake (Lake Søbygård, Denmark)

Jensen¹,

Kristensen²,

Christensen³

et al. 1992

Intl Review of Hydrobiology

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A detailed mass balance on nitrogen was carried out in shallow and hypertrophic Lake SobygBrd during 4.5 years before through 2.5 years after a 36 % reduction in nitrogen loading. Annual mean loss rate of nitrogen was 159-229 mg N m-2 d-1 before the loading reduction and 125 mg N m-2 d-1 after. In spite of a short hydraulic retention time (18-27 days) the proportion of nitrogen loading lost in the lake was high (38-53 %) and not affected by changes in loading. Calculated denitrification accounted for 86-93 % of the loss rate, while 7-14 % was permanently buried. Marked seasonal variations in the loss percentage were found during the season, ranging from 23 % in first quarter to 65 % in third quarter. The seasonal variation in the loss percentage of nitrogen

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Section: Introductionmentioning

confidence: 56%

Nitrogen Loss and Denitrification as Studied in Relation to Reductions in Nitrogen Loading in a Shallow, Hypertrophic Lake (Lake Søbygård, Denmark)

Jensen¹,

Kristensen²,

Christensen³

et al. 1992

Intl Review of Hydrobiology

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“…Compared to a previous model of nitrogen cycling in the Westerschelde (Billen et al, 1985(Billen et al, ,1986, we model lower maximal denitrification rates in the water column (0.25 gN m-3 dd-' compared to 0.7 gN m-3 d-' in Billen etal., 1985) while only about 21% of total nitrogen, 33% of inorganic nitrogen, is removed in our model compared to 40-50% as estimated by Billen and co-workers. This discrepancy requires a more thorough analysis.…”

Section: Deni'rifi=ation Nitrification Mineralisation Primary Productionmentioning

confidence: 98%

“…The process depends on temperature (Ql0 formulation) and is inhibited in anaerobic conditions (hyperbolic relation). Owing to the slow development of nitrifying bacteria (Billen et aL, 1986) there is an upper limit to the rate of nitrification. This was modeled as a hyperbolic relationship with ammonium (Helder & De Vries, 1983;Somville et aL, 1982).…”

Section: Sdmentioning

confidence: 99%

Nitrogen dynamics in the Westerschelde estuary (SW Netherlands) estimated by means of the ecosystem model MOSES

Soetaert¹,

Herman²

1995

Major Biological Processes in European Tidal Estuaries

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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)(1981)(1982)(1983)(1984)(1985)(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 nutrienf profiles hat 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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“…Somville et al, 1982 ;Billen et al, 1985Billen et al, , 1986 . In 31 the Elbe estuary a number of studies on microbial activities have been done (i .e .…”

Section: Introductionmentioning

confidence: 99%

Comparison of heterotrophic bacterial production rates in early spring in the turbid estuaries of the Scheldt and the Elbe

1995

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In spring bacterial production rates were estimated by tritiated thymidine incorporation in the turbid estuaries of the rivers Scheldt and Elbe . Bacterial production rates in the Scheldt were 5 times higher than in the Elbe . In the Scheldt bacterial production rates correlated better with the DOC concentration than in the Elbe . Organic matter concentrations in the marine part of the estuaries were the same while in the brackish part concentrations in the Scheldt were much more higher. In the Scheldt, but not in the Elbe, oxygen depletion occurred in the maximum turbidity zone caused by bacterial growth and respiration . The water in the Scheldt was well-mixed while in the turbidity maximum of the Elbe salinity and bacterial production was higher near the bottom than at the surface . Nutrient concentrations in the Scheldt were higher than in the Elbe . Bacterial production rate values in the Scheldt are among the highest reported in the literature . The relatively high bacterial production rates in both estuaries are caused by a high load of waste water. Comparison of bacterial growth rates and water residence time suggests an intensive grazing by probably protozoa. Production rates showed a tidal dynamic . In the Elbe high current velocities caused resuspension of sediment and increased bacterial production rates near the bottom . The high production rates in the turbidity maximum and freshwater part of both estuaries show that a large amount of organic matter is degraded in this region .

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The Terrestrial-Marine Interface: Modelling Nitrogen Transformations During its Transfer Through the Scheldt River System and its Estuarine Zone

Cited by 10 publications

References 13 publications

Nitrogen Loss and Denitrification as Studied in Relation to Reductions in Nitrogen Loading in a Shallow, Hypertrophic Lake (Lake Søbygård, Denmark)

Nitrogen Loss and Denitrification as Studied in Relation to Reductions in Nitrogen Loading in a Shallow, Hypertrophic Lake (Lake Søbygård, Denmark)

Nitrogen dynamics in the Westerschelde estuary (SW Netherlands) estimated by means of the ecosystem model MOSES

Comparison of heterotrophic bacterial production rates in early spring in the turbid estuaries of the Scheldt and the Elbe

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