The mud deposits and the high turbidity in the Belgian–Dutch coastal zone, southern bight of the North Sea

A geometric method to study water and sediment exchange in tidal harbors

“…Most of these suspended sediments originate from the English Channel and are transported into the North Sea through the Strait of Dover. In the high-turbidity area, the depth-averaged SPM concentrations of minimum 20-70 mg/l and maximum 100-600 mg/l have been measured (Fettweis and Van den Eynde 2003) Over the period 2005-2007, on average, 36×10 5 tons dry matter (TDM)/year was dredged in the harbor of Zeebrugge every year and dumped on authorized dumping sites in the Belgian part of the North Sea (Lauwaert et al 2008). This number includes maintenance dredging, but excludes capital dredging.…”

Long-term influence of maritime access works on the distribution of cohesive sediments: analysis of historical and recent data from the Belgian nearshore area (southern North Sea)

“…Comparison between the SPM transport entering and leaving the Belgian Continental Shelf and the quantities dredged and disposed at sea shows that an important part of the SPM is involved in the dredging/disposal cycle (Fettweis and Van den Eynde 2003). The disposal of finegrained sediment temporarily increases SPM concentrations in the water column (Van den Eynde and Fettweis 2006).…”

Organic matter input and processing in two contrasting North Sea sediments: insights from stable isotope and biomass data

“…We investigated organic matter input at 2 contrasting sediments on the Belgian Continental Shelf (BCS). The BCS is situated in the Southern Bight of the North Sea and is a complex system of beaches, gullies and sandbanks that are characterized by different sediment types ranging from clays to coarse sands (Fettweis & Van den Eynde 2003, Van Hoey et al 2004). The BCS receives high nutrient inputs from the rivers Rhine, Meuse and Scheldt that give rise to pronounced spring blooms of diatoms and Phaeocystis, reaching concentrations of 10 to 50 μg chl a l -1 (van der Zee & Chou 2005) and an annual net primary production of 134 to 213 g C m -2 (Lancelot et al 2005).…”

“…The BCS receives high nutrient inputs from the rivers Rhine, Meuse and Scheldt that give rise to pronounced spring blooms of diatoms and Phaeocystis, reaching concentrations of 10 to 50 μg chl a l -1 (van der Zee & Chou 2005) and an annual net primary production of 134 to 213 g C m -2 (Lancelot et al 2005). The sediments of the BCS are interesting sites to follow the input and fate of organic matter, because hydrodynamic conditions such as current velocity (1 to 2 m s -1 ) and bottom shear stress (0.8 to 1.5 Pa) suggest comparable hydrodynamic conditions on the BCS (Fettweis & Van den Eynde 2003). An important factor governing differences in sediment type is the presence of a high turbidity zone in front of the coast, resulting in coarser offshore sediments and finer coastal sediments (Fettweis & Van den Eynde 2003).…”

“…The sediments of the BCS are interesting sites to follow the input and fate of organic matter, because hydrodynamic conditions such as current velocity (1 to 2 m s -1 ) and bottom shear stress (0.8 to 1.5 Pa) suggest comparable hydrodynamic conditions on the BCS (Fettweis & Van den Eynde 2003). An important factor governing differences in sediment type is the presence of a high turbidity zone in front of the coast, resulting in coarser offshore sediments and finer coastal sediments (Fettweis & Van den Eynde 2003). Hence, whereas coastal and offshore sediments are subjected to similar physical forces, coastal sediments are more stable and less permeable due to the input of fine particles from the water column (see 'Study site and cruises' in 'Materials and methods').…”