Dredging of contaminated sediments in the weser estuary: Chemical forms of some heavy metals

Abstract

Concentration and chemical forms of metals in bottom sediments and dredged mud of the Weser Estuary were studied. The sediments with the highest metal contents are found in the harbour basins of Bremen and in the mud shoal near Nordenham. Association types of the metals can be divided into 2 groups: metals with relatively high potential of mobilization, such as Cd, Zn, Mn, and Ni and those that are strongly bound on particles ‐ Cr, Cu, Pb and Fe. An estimation of the bioavailability of these metals based on chemical extraction studies is relevant to problems encountered during disposal of dredged materials.