A contribution to the study of nitrogen dynamics in the Scheldt Estuary: Importance of the dissolved organic N pool

Student thesis: Master's Thesis


The river Scheldt and it’s estuary crossing France, Belgium and The Netherlands on its way to the North Sea is an ideal place to observe the dynamical variation of N.
Most of the studies done so far on the N-cycle in the Scheldt estuary focused on the inorganic forms (nitrate, nitrite and ammonium) with very little information on the organic fraction, more particularly on the dissolved organic N (DON). Traditionally, dissolved organic nitrogen (DON) has been viewed as a large refractory pool that is unimportant to microbial nutrition. Research over the past decade has however transformed this view; more and more people begin to focus on it.
One of the major problems in studying DON dynamics are linked to its precise quantification.
Total dissolved nitrogen was measured according to the method described in Dafner et al. (1999) using a Microwave Sample Preparation System, CEM Corporation USA, model MARS 5, equipped with Teflon PFA sample vessels which are transparent for microwave energy. Prior to its use, this method was tested and the detection limit, precision and efficiency was calculated.
In this work we focused on the estuary and took samples along from Antwerp to the North Sea at 4 seasons. The concentrations of all different N compounds were measured, and these profiles were used to make N-budgets based on a one-box model. With the results, we try to explain what happens with N inside the estuary and we also see how important DON is in the N cycling and how many percentage it is.
Date of Award2006
Original languageEnglish
SupervisorNatacha Brion (Promotor), Ludwig Triest (Jury), Willy Baeyens (Jury) & Frank Dehairs (Jury)

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