Historical and emerging contaminant trace elements and isotopes. Sources, fluxes and cycling of Pb isotopes, Pt, Tl, Te, Ag and Gd in the oceans – a contribution to GEOTRACES

• Applicants: Professor Dr. Eric Achterberg; Professorin Dr. Andrea Koschinsky
• Subject Area: Oceanography
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 546298393

The international GEOTRACES program aims to dissect the inputs and cycles of trace elements and their isotopes to understand their importance for the state of the oceans and assess the influence of global change on trace element processes. While the focus so far has been mainly on biogenic trace elements, which as micronutrients have a significant relevance for the bioproductivity of the oceans, oceanic material cycles are increasingly influenced or even overridden by anthropogenic inputs of economically newly used elements. A typical example of a traditional metallic pollutant is lead (Pb), whose decades-long anthropogenic input can be traced through its isotopic signature to the remotest regions of the oceans. New technologies, e.g., for green energy production, or novel medical products, have been increasingly introducing novel potential pollutants such as gadolinium (Gd), platinum (Pt), tellurium (Te), thallium (Tl), and silver (Ag) into the oceans; since little is also known about the natural distribution of these trace elements, there is a risk that increasing anthropogenic inputs will overprint the natural signatures and that potential adverse effects from these non-essential but potentially toxic elements will be detected too late. Applicants Achterberg and Koschinsky have contributed significantly to the knowledge of the GEOTRACES program through numerous GEOTRACES expeditions in the Atlantic, Pacific, Black Sea, and Mediterranean from the German side and have a unique collection of preserved trace metal-clean water samples collected from these cruises. In the proposed project, we plan to use Pb isotope signatures as well as Gd as tracers for novel metal input in profiles of selected ocean regions to identify anthropogenic metal inputs. Through analysis of the Pt, Te, Tl, and Ag in comparison with Gd and its potential anthropogenic anomalies we aim to dissect the geogenic and anthropogenic inputs of these trace elements and in which ocean regions their potentially adverse effects could manifest. Our hypothesis is that regions with increased atmospheric or other land-based inputs will have elevated concentrations of the newly emerging pollutant trace elements, counter to declining concentrations of anthropogenic lead. We expect that predictions for other newly introduced trace metals that behave in a geochemically similar manner can be made based on these new findings.

• DFG Programme: Research Grants