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Item type:Publication, Access status: with files , The Weser Estuary : a study on heavy metal behaviour under hydrographic and water quality conditionsIn continuation of fixed anchor stations the behaviour of heavy metals was also studied in longitudinal sections in the bottom sediments (Calmano et al. 1982) and in the water (this paper). There are changes in concentrations of dissolved metals in water and changes in contents of metals in seston (suspended matter) in dependence on tides (Duinker et al. 1982 b). These changes can be related to the passing of different water bodies and different seston types, respectively, at the place of observation. In addtition, more changes were found at various hydrographically defined "stretches" along the whole length of the estuary. These changes were attributed to dilution of estuarine water by coastal seawater in the lower estuary; but in the mud reach in the central estuary they were attributed to the interchange with mud (alternating settling and resuspension of loose sediment particles through tides). In the central and the upper estuary they could be attributed to the influence of very low salinity, to the predominance of either organic matter or clay or quartz in seston, to the state of aggregation of seston particles which depends on salinity, the nearness to the mud reach and perhaps the amount of the particles in water; and the changes could further be attributed to emissions from industrial sites, sewage outfalls and the dumping of dredge spoil. Relation to organic water quality criteria were not found. The bioavailability of particulate metals is discussed: it is comparatively high in Cd, Zn and Mn (80-95%) and lower in other elements.Publicationtype: Journal Article467 588 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Dredging of contaminated sediments in the Weser Estuary : chemical forms of some heavy metalsConcentration 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.Publicationtype: Journal Article464 495