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Improvements in spectral wave modeling in tidal inlet seas
The performance of the spectral wind wave model SWAN in tidal inlet seas was assessed on the basis of extensive wave measurements conducted in the Amelander Zeegat tidal inlet and the Dutch Eastern Wadden Sea, as well as relevant data from other inlets, lakes, estuaries and beaches. We found that three aspects required further attention.
Erosion protection of barrier beach strips between river-fed lagoons and the sea
Multi-criteria decision analysis of test endpoints for detecting the effects of endocrine active substances in fish full life cycle tests
This study describes how the technique of multicriteria decision analysis (MCDA) was used to elicit the views of fish ecologists, aquatic ecotoxicologists and statisticians on optimal experimental designs for assessing the effects of endocrine active chemicals on fish.
Managing coastal evolution in a more sustainable manner : the Conscience approach
Stand van zaken rond het verspreiden van baggerspecie
De beoordeling of baggerspecie verspreid mag worden op land is in het Besluit Bodemkwaliteit (Bbk) uitgewerkt. Wat in het Bbk niet beschouwd wordt is het effect van het op land zetten van baggerspecie. Door het in contact komen met lucht treden reacties op die de mobiliteit van onder andere zware metalen en arseen beinvloeden. Dit kennishiaat van tijdelijke effecten in de overgang van nat naar droog en vice versa is eerder geconstateerd bij het storten van landbodems in zandwinputten.
Verkennende studie naar lozing van microplastics door rwzi’s
In dit artikel wordt aangetoond dat microplastics ook de Nederlandserioolwaterzuiveringsinstallaties bereiken en voor een deel weer geloosd worden als component via het effluent. Tevens zijn microplactics gevonden in watermonsters van de Noordzee. De emissiebronnen hiervan zijn divers.
Pleidooi voor landelijk stroomgebiedenmeetnet
Grondwater als buffer om droogte te voorkomen
The effect of nitrite inhibition on the anammox process
The negative effect of nitrite on anammox activity has been reported widely during the past decade. Although the adverse effect is clear, conflicting reports exist on the level at which it occurs and its reversible/irreversible nature. An in depth study on nitrite inhibition therefore was performed in which the influence of environmental factors was evaluated. Anammox activity was measured in anammox granules by continuously monitored standardized manometric batch tests extending the interpretation by evaluation of lag times, maximum conversion rates during the tests and substrates/product conversion ratios. The granules where obtained from a one-stage anammox reactor, the dominant anammox organisms belonged to the Brocadia type. The observed 50% activity inhibition for nitrite (IC50) was 0.4 g N L-1. The activity recovered fully after removal of the nitrite. Conversion in fresh medium after exposure to up to 6 g NO2 N L-1 for 24 h showed less then 60% loss of activity. Presence of ammonium during nitrite (2 g N L-1) exposure resulted in a stronger loss of activity after nitrite exposure (50% and 30% in presence and absence of ammonium respectively). Presence of oxygen during nitrite incubation led to a maximum activity reduction of 32%. The recovery after exposure indicates that the adverse effect of nitrite is reversible and thus inhibitory rather than toxic in nature. Similarities between exposure at three different pH-values indicate that nitrite rather than nitrous acid is the actual inhibiting compound.
Model experiments on piled embankments
A series of twelve 3D laboratory model tests was performed on piled embankments. In the first part of a two-part study, the measured load distribution, deformation, and strains are presented and analysed. In the second part, the measurements are compared with calculations using EBGEO (2010), and suggestions are given for improvements to this calculation model.