ABSTRACT
Large amounts of trace metals are transported by various rivers in the direction of the southern North Sea. The major part of the heavy metal load originates from anthropogenic sources. The Rhine River is the most important fluvial source of trace metals for the North Sea. This influence is reflected in the sediments along the coast, in the Wadden Sea area in the northern part of the Netherlands, and in two freshwater bodies fed by the Rhine River (Figure 1). The high metal load of the Rhine River is not of recent origin. In fact, this river has been polluted with trace metals for more than 60 years. 1 Cadmium and zinc concentrations in sediment samples from the Rhine River in 1922 were 4.4 and 1050 μg/g, respectively. The concentrations of cadmium in 1922 were already 15 times the baseline level of 0.25 μg/g.
