Dr. Hannelore Waska

The cycling of trace metals, which have a major ecosystem impact due to their function as essential micronutrients in aquatic ecosystems, is often intrinsically linked with the cycling of organic matter. For example, by colloidal association or complex formation, dissolved organic matter (DOM) is capable of stabilizing otherwise insoluble trace metals in the water column. Such mobilized metal-DOM compounds can be transported over long distances from terrestrial or deep-sea sources to nutrient-depleted open surface oceans.
In my research, I investigate the role of coastal groundwater-surface water interaction zones as dynamic formation sites of stable metal-DOM compounds, and develop new analytical methods for the identification of these metal-DOM compounds, which display distinct geochemical behaviors depending on their unique elemental compositions and structures. The challenge lies within the high complexity of DOM, which provides thousands of organic ligands in pico- to nanomolar concentrations. Therefore, I am combining well-established trace metal speciation techniques such as competitive ligand equilibration adsorptive stripping voltammetry (CLE-ASV) with state-of-the art DOM analytics such as the high-resolution 15T Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR-MS) available in the laboratory of the Max Planck Research Group for Marine Geochemistry in Oldenburg.
Due to its multi-disciplinary and analytically diverse approach, this project includes a network of collaborations with inorganic and organic geochemistry research groups from the University of Oldenburg, University of Bremen, and Jacobs University Bremen.