Scheldt estuary

In all three sampling periods, relatively high levels (2—2.2 p,g NPEO g-1 and 1—4.1 p,g NP g-1) were found in particulate matter samples taken at Terneuzen in the canal that links the Belgian city of Ghent to the western Scheldt estuary. 

Scheldt estuary (The Netherlands) Estuarine sediment AgPEOi i2 <0.0003-0.240a [13]... 

Jonkers et al. used LC-ES-MS to analyse sediments from the Scheldt estuary, The Netherlands [13]. Sediment concentrations ranged from <0.0003 to 0.242 and from <0.0003 to 1.080 pg g-1 dry weight for A9PEO and NP, respectively. The highest concentrations were found near an industrial area and a commercial harbour. In most sediments, no A9PEC were found. 

Levels in SPM tended to decrease along the Dutch coast in a northerly direction with increasing distance from the main (Rhine/Meuse and Scheldt) estuaries. Locally in the western Scheldt estuary near the same industrial area mentioned in the preceding paragraph, levels in SPM up to 22 jjLg AgPEO g-1 were reported. 

A comparison of Rhine, Meuse and Scheldt estuaries revealed that in the Rhine estuary, with its relatively short residence times of the water, concentrations on estuarine SPM were similar to or higher (ratios estuarine/freshwater >1) than those upstream (i.e. on freshwater SPM from the river), whereas in Meuse and Scheldt estuaries with longer residence times of the water, particulate matter concentrations of A9PEO are much lower (ratios < 1) than in samples taken upstream (see Fig. 6.4.3). For NP this phenomenon is also... 

Biomagnification of PFOS in the estuarine food chain of the Western Scheldt estuary was observed by de Vos et al. [116] On the other hand, it is not clear whether there is a difference between the concentrations of PFCs inedible fish from remote versus highly industrialised or urbanised areas or not. However, Gulkowska et al. [133] observed slightly higher PFOS concentrations in fish from the highly urbanised and industrialised areas. 

The sample locations are shown on the map in Figure 1. Euromonding (Port of Rotterdam) and the North Sea Canal (Port of Amsterdam) are well-known polluted areas. The sites in the North Sea are situated at the end of the estuarine harbour areas, except for Noordwijk (site 6), which is a t5 ical coastal location. Two relatively clean sites, the Oesterput in the Eastern Scheldt estuary (site 14) and Ussehneer near Enkhuizen (site 12), were also sampled and used as saltwater and freshwater reference sites respectively. In the Port of Rotterdam transect the salinity gradient is continuous whilst in the Port of Amsterdam transect the salinity gradient is interrupted and more complex due to canalisation. The numbers of the sampling sites correspond with the site numbers reported previously for the results of the chemical sediment and flounder liver analyses (De Boer 2001). The transects were sampled from 19 to 26 September 1996. 

De Wolf, H., de Coen, W, Backeljau, T, Blust, R. (2001). Intersex and sterility in the periwinkle Littorina littorea (Molluscs Gastropoda) along the Western Scheldt estuary, the Netherlands. Marine Environmental Research, 52,249-255. 

Voorspoels, S., Covaci, A., Maervoet, J., De Meester, I. and Schepens, P. (2004). Levels and profiles of PCBs and OCPs in marine benthic species from the Belgian North Sea and the Western Scheldt Estuary, Marine Pollution Bulletin, 49 393-404. 

To illustrate one type of speciation research, i.e. the determination of the apparent complexation capacity for copper (CCqu) and the conditional stability constant (K1), examples are given for three marine areas, viz. the Scheldt estuary, the Southern Bight of the North Sea and the open north Atlantic Ocean. A hypothetical model is presented giving the complexation capacity across the land-sea boundery from river to ocean. 

In natural systems therefore part of the complexation capacity might be caused by colloidal material. This was demonstrated in experiments on the complexation capacity of samples from the Scheldt estuary at different salinities, determined as function of several concentration steps, using a hollow fiber ultrafiltration set up with a theoretical cut off of MW 5000 (Kramer and Duinker, 1984a). 

Complexation Capacity (CC), conditional stability constant (K1), temperature, pH, oxygen and suspended matter content in the river Scheldt estuary at different salinities. 

Fig. 2. Means of triplicate analysis of apparent Scheldt estuary copper complexation capacity in the river Scheldt estuary at various salinities.

Muhaya, B.B.M., M. Leermakers, and W. Baeyens. 1997. Total mercury and methylmercury in sediments and in the polychaete Nereis diversicolor at Groot Buitenschoor (Scheldt estuary, Belgium). Water Air Soil Pollut. 94 109-123. 

Baeyens, W., C. Meuleman, B. Muhaya, and M. Leermakers. 1998. Behaviour and speciation of mercury in the Scheldt estuary (water, sediments and benthic organisms). Hydrobiologia 366 63-79. 

Using the above equations, model simulations of the various Hg species in the Scheldt estuary were carried out using the TK-Solver program.115 A conditional stability constant of 1019 was estimated for Hg-humic acid interactions in the Scheldt. 

Baeyens, W. 1998. Evolution of trace metal concentrations in the Scheldt estuary (1978-1995). A comparison with estuarine and ocean levels. Hydrobiologia 366 157-167. 

Figure 5.6 Biogeochemical processes affecting their flux rates across the air-water interface of the four biogases (N2O, O2, CO2, NH3) analyzed in a full transient, one-dimensional reactive transport CONTRASTE model (Coupled, networked, transport-reaction algorithm for strong tidal estuaries) for the Scheldt estuary (The Netherlands) (Modified from Vanderborght et al., 2002.)...

Dame, R.F., Dankers, N., Prins, T., Jongsma, H., and Smaal, A. (1991) The influence of mussel beds on nutrients in the western Wadden Sea and the eastern Scheldt estuaries. Estuaries 14, 130-138. 

Fettweis, M., Sas, M., and Monbaliu, J. (1998) Seasonal neap-spring and tidal variations of cohesive sediment concentration in the Scheldt estuary, Belgium. Estuar. Coastal Shelf Sci. 47, 21-36. 

Mariotti, A., Lancelot, C., and Billen, G. (1984) Natural isotopic composition of nitrogen as a tracer of origin for suspended matter in the Scheldt Estuary. Geochim. Cosmochim. Acta 48, 549-555. 

Vanderborght, J.P., Wollast, R., Loijens, C. M., and Regnier, P. (2002) Application of a transport-reaction model to the estimation of biogas fluxes in the Scheldt estuary. Biogeochemistry 59, 207-237. 

Zwolsman, J.J.G. (1994) Seasonal variability and biogeochemistry of phosphorus in the Scheldt Estuary, South-West Netherlands. Estuar. Coastal Shelf Sci. 39, 227-248. 

Janak, K., Covaci, A., Voorspoels, S., Becher, G. (2005) Hexabromocyclododecane in marine species from the Western Scheldt estuary diastereoisomer- and enantiomer-specific accumulation. Environ. ScL Technol, 39 1987-1994. 

Van de Vijver, K. I., Hoff, P. T., Van Dongen, W., Esmans, E. L., Blust, R., De Coen, W. Exposure patterns of perfluorooctane sulfonate in aquatic invertebrates from the Western Scheldt Estuary and the southern North Sea. Environ. Toxicol. Chem., 22 2037-2041 (2003). 

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