Chemical characterization of suspensions and sediments in the North Sea and Scheldt estuary
Van Alsenoy, V.; Van Put, A.; Bernard, P.; Van Grieken, R. (1989). Chemical characterization of suspensions and sediments in the North Sea and Scheldt estuary, in: Pichot, G. (Ed.) Progress in Belgian Oceanographic Research 1989: proceedings of the North Sea Symposium held in Ghent, 14 February 1989. pp. 351-368
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| Auteurs | | Top |
- Van Alsenoy, V., meer
- Van Put, A.
- Bernard, P.
- Van Grieken, R., meer
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| Abstract |
From December 1987 to July 1988, more than 80 sediment and 20 suspension samples were collected in the river Scheldt and along the Belgian coast. The concentration in the bulk and the clay/silt fraction of the following elements was using X-ray fluorescence and atomic absorption spectrometry: K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Cd and Hg. The relative abundance of the fractions <63 µm and <20 µm was determined using wet sieving after drastic deflocculation. This method showed to give the most realistic approximation for the real distribution, as well as the most accurate concentrations of the elements in the clay/silt fraction. For 10 selected samples the total granulometric distribution was obtained by means of dry sieving, wet sieving and Coulter counting. Although the obtained number distributions were all quadratic functions, significant differences in mass distributions were found for samples from different areas. These differences were detected both in the sand and the clay/silt fraction. The obtained concentrations were interpreted as a function of time and area and normalized to the clay/silt fraction. This results in the identification of two major populations of sediments in the Belgian coastal zone and the river Scheldt, each ruled by different pollution factors. Automated electron probe X-ray micro-analysis was used to characterize the individual suspension and sediment particles. The abundance variations of some particle types with salinity and as a function of location and time, provide information about geochemical and physical processes. It appeared that 80 % of all the investigated particles contained mostly silicon ( SiO2 > 40 %) and probably , of quartz or diatoms, and K-, Ca- or Fe-rich alumino-silicates. The less abundant particle types were identified as rich in Ti, Fe+P, Fe+S, Fe or Ca. The mixing ratio of marine suspensions with estuarine suspended matter can be estimated by the relative abundance of the calcite particle type. The occurrence of the Fe-rich particle type is important with respect to pollution studies, as it is assumed that high amounts of trace elements are absorbed and/or coprecipitated with these particles. |
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