To map the pollution situation of sediments near the Belgian North Sea coast and in the Scheldt estuary, to compare the obtained results with older data, and to evaluate the evolution with time, sediments from 20 stations sampled at 4 different dates were analyzed for the grain-size distribution, elemental composition, carbonate- and organic carbon content. Through normalization to the abundance of the clay/silt traction it was possible to determine some hot spots. Based on inter-element correlation, two different populations of sediments with different pollution lever were identified. Due to the intensive dredging in this area (15. 106 m3/year in he Scheldt river) and natural transport, changes in the distribution of particulate/dissolved heavy metals can occur. Experiments were performed to estimate the distribution coefficients and the remobilization rate of some heavy metals (Cd, Pb, Zn, Cu) when sediments are subjected to changes in the environmental conditions. Some of the most polluted sediments were equilibrated in solutions of different salinity and the desorption process was studied as a function of time. Cd is the element that desorbs most easily from the sediments; up to 10-15% of the total Cd content may remobilize. Cu on the contrary is the element which remains most in the sediment. The ease of mobilization of Zn and Pb is intermediate. Remobilization is most important at high salinity.
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