STARDUST II - Spatial and Temporal Assessment
of high Resolution Depth profiles Using novel Sampling Technologies The fate of pollutants in fluvial and marine sediments in cross-border zones
Different mobilization mechanisms control the metal distribution in surface sediments of the Belgium coastal zone (BCZ) and the anoxic Gotland basin (GB). This mobilization was studied using DGT (diffusive gradients in thin films): vertical one-dimensional (1D) profiles of Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn were measured at 5 mm intervals, while two-dimensional (2D) high-resolution (100 µm) images of smaller zones of the sediment profile were obtained on separate DGT probes. Removal of dissolved Cd, Cu, and Pb in BCZ sediments caused steep vertical gradients at the sediment–water interface that were well replicated in 1D profiles and 2D images. While 1D profiles showed apparent coincident maxima of Co, Mn, and Fe, 2D images revealed mutually exclusive Co and Fe mobilization. Correlation analysis supported this observation and showed a consistent linkage between Co and Mn. Sharp maxima of some metals in the vertical 1D profiles of GB sediment were attributed to localized mobilization in microniches. Examination of an ~1 mm diameter Cu and Ni maximum in 2D, defined by ~300 data points, showed that the metals were supplied from localized decomposition of reactive organic material, rather than from reductively dissolving Fe or Mn oxides, and that they were removed as their sulfides.
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STARDUST II is a project funded by the INTERREG III A programme (France/Walloon Region/Flanders
French-Flemish subprogramme) of the European Community's Regional Development Fund.
Hosted by the Flanders Marine Institute (VLIZ)