Advances in Understanding Mobilization Processes of Trace Metals in Marine Sediments

Area of Science:

• Environmental Science
• Geochemistry
• Marine Science

Background:

• Metal distribution in marine sediments is influenced by complex biogeochemical processes.
• Understanding metal mobilization is crucial for assessing sediment quality and environmental impact.

Purpose of the Study:

• To investigate and differentiate metal mobilization mechanisms in Belgium coastal zone (BCZ) and Gotland basin (GB) sediments.
• To utilize high-resolution imaging techniques for detailed analysis of metal distribution at the micro-scale.

Main Methods:

• Employed diffusive gradients in thin films (DGT) for measuring vertical 1D profiles and 2D high-resolution images of metal concentrations.
• Analyzed trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) at millimeter and micrometer scales.
• Applied correlation analysis to identify metal linkages and sources.

Main Results:

• BCZ sediments showed steep gradients for Cd, Cu, and Pb at the sediment-water interface.
• 2D imaging revealed distinct Co and Fe mobilization patterns, contrasting with 1D profiles, and confirmed a Co-Mn linkage.
• GB sediments exhibited localized metal maxima attributed to organic matter decomposition and sulfide precipitation.

Conclusions:

• Mobilization mechanisms for metals differ significantly between the BCZ and GB.
• High-resolution DGT imaging provides critical insights into micro-scale metal transport and sources, complementing traditional 1D profiling.
• Localized decomposition of organic matter is a key source for Cu and Ni mobilization in anoxic sediments.