Marine Pollution Bulletin 194 (2023) 115396 11 219). Therefore, possible anthropogenic influences of dissolving anodes should result in lower Ga/In of the sediment samples. Indeed, measured Ga/In ratios of this study are mostly within the reference range of Klein et al. (2022a). Solely the areas N-3 (2021) and N-4 (2022) show Ga/In ratios exceeding this given reference range. Currently, Ga/In ratios of the analyzed sediment samples do not suggest sufficiently large anthropogenic inputs of Ga or In to significantly alter Ga/In ratios. The plot of n(87Sr)/n(86Sr) against Ga/In in Fig. 5B shows, that the sediments of area N-4 form a distinct group indicating a different sediment type and therefore a different origin compared to other investigated areas which is in good agreement to the conclusions based on Sr isotope amount ratio analysis. 5. Conclusion The data shows that mass fractions of the selected tracer elements in the sediment are currently predominantly within the range of the known variability in the study areas. Locally elevated mass fractions were for Pb and Cd. For the first time, data could be generated for the tracers In and Ga in OWFs in the German Bight. The high dynamics in the area and the associated large-scale water and particulate matter exchange contribute to the measured mass frac- tions that were mostly within the range of the known variability for the German Bight. Based on the Ga and In elemental mass fraction data and the prevailing dilution and distribution processes, there are currently no direct effects discernible due to the use of galvanic anodes. For a better source allocation sound geogenic background levels for emerging con- taminants are necessary, which are currently lacking for the North Sea. In addition, limited information about the biogeochemistry of Ga and In is currently available. However, due to the specific situation in the German Bight in terms of historical pollution, a wide range of anthro- pogenic sources and highly dynamic environmental processes, it is currently very challenging to fully differentiate the additional pollution load caused by OWFs. Due to the continuous operation and development of offshore wind energy, the chemical emissions from corrosion protection will further increase keeping in mind the planned development e.g. for the German EEZ (30 GW until 2030) as well as the entire EU North Sea area (300 GW until 2050). To measure the metal input from galvanic anodes as well as the general operation we propose to continue the monitoring of the tracer elements in order to trace possible emissions by OWFs. Moreover, we suggest the application of Ga/In and potentially other element ratios as further tool, as the Ga/In ratio from galvanic anodes differentiates greatly from Ga/In in North Sea sediments. Sr isotope amount ratios can help to differentiate geogenic from anthropogenic signals and account for differences in sediment types. Although the study cannot proof the direct impact of OWF emissions on environmental concentrations, around 13 years after the operational start of the first OWF within the German Bight, it is clear that galvanic anodes are per se a continuous source of metal emissions and thus are a new source of pollution within the marine environment. Further in- vestigations should contribute to better assess possible medium- to long- term effects of such chemical emissions on the marine environment. Based on long-term monitoring of the critical elements, possible accu- mulations caused by the corrosion protection of offshore installations could be observed and evaluated in the future. Furthermore, future OWF projects should also consider alternative corrosion protections tech- niques during their planning to reduce chemical emissions. Funding This work was supported by the BSH through the projects OffChEm I and II (BSH contract codes: 10036781 and 10052123, Hereon contract codes: 17/2017 and 169/2021) and by the German Federal Ministry for Digital and Transport (BMDV) in the context of the BMDV Network of Experts. Ole Klein was funded by the European Metrology Program for Innovation and Research (EMPIR) project MetroCycleEU (Funder ID: 10.13039/100014132, Grant number: 20IND01 MetroCycleEU). CRediT authorship contribution statement Anna Ebeling: Methodology, Validation, Investigation, Data cura- tion, Writing – original draft, Visualization. Dominik Wippermann: Validation, Investigation, Data curation, Writing – original draft, Visu- alization. Tristan Zimmermann: Methodology, Investigation, Writing – original draft. Ole Klein: Investigation, Data curation, Writing – review & editing, Visualization. Torben Kirchgeorg: Conceptualization, Investigation, Project administration, Writing – review & editing. Ingo Weinberg: Conceptualization, Project administration, Writing – review & editing. Simone Hasenbein: Investigation, Writing – review & edit- ing. Anna Plaß: Investigation, Writing – review & editing. Daniel Profrock: Conceptualization, Investigation, Writing – review & editing, Project administration, Funding acquisition. Declaration of competing interest The authors declare the following financial interests/personal re- lationships which may be considered as potential competing interests: Anna Ebeling reports financial support was provided by Federal Maritime and Hydrographic Agency. Dominik Wippermann reports financial support was provided by Federal Maritime and Hydrographic Agency. This work was supported by the BSH through the projects OffChEm I and II (BSH contract codes: 10036781 and 10052123, Hereon contract codes: 17/2017 and 169/2021) and by the German Federal Ministry for Digital and Transport (BMDV) in the context of the BMDV Network of Experts. Ole Klein was funded by the European Metrology Program for Innovation and Research (EMPIR) project MetroCycleEU (Funder ID: 10.13039/100014132, Grant number: 20IND01 MetroCycleEU). Data availability Data will be made available on request. Acknowledgements We thank Nathalie Voigt, Catharina Petrauskas, Bettina Rust, Andrea Pieper and Svenja Faust for their support in the lab and preparations of sampling campaigns. Bettina Rust, Nathalie Voigt, Johanna Irrgeher, Andrea Pieper, Lisett Kretzschmann, Svenja Faust, Marcel Herbst, Simon Tewes, Francisco de la Granda Grandoso, Burkhard Erbsloh and Fadi el Gareb are acknowledged for help during the sampling campaigns. We thank Carlotta Pehlke and Jonas Ludwig for their help to analyze isotope ratios of Sr. The anonymous reviewers are acknowledged for their feedback. Further, we would like to thank both crews of the research vessels Atair (BSH) and Ludwig Prandtl (Hereon). Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi. org/10.1016/j.marpolbul.2023.115396. References Ackermann, F., Bergmann, H., Schleichert, U., 1983. Monitoring of heavy metals in coastal and estuarine sediments - a question of grain-size: <20 ?m versus <60 ?m. Environ. Technol. Lett. 4, 317–328. https://doi.org/10.1080/09593338309384212. Andrews, M.G., Jacobson, A.D., Lehn, G.O., Horton, T.W., Craw, D., 2016. Radiogenic and stable Sr isotope ratios (87Sr/86Sr, ?88/86Sr) as tracers of riverine cation sources and biogeochemical cycling in the Milford Sound region of Fiordland, New Zealand. Geochim. Cosmochim. Acta 173, 284–303. https://doi.org/10.1016/j. gca.2015.10.005. A. Ebeling et al.