Research interests:
Hydrothermal influence to the ocean’s biogeochemistry
Hydrothermal circulation of organic and inorganic elements and their distribution in the rising, non-buoyant Plume
Research project:
Different roles of organic complexes for the transport of Cu and Fe in deep-sea and shallow hydrothermal vent fluids and plumes
Hydrothermal vent systems appear at the seafloor in geologically active areas such as mid-ocean ridges, volcanic arc systems, backarc basins and hotspot volcanoes. Their fluids withhold a unique chemistry created by fluid-rock interaction in the subsurface, which leads to a transport of dissolved metals and other compounds towards the seafloor. The actual metal- and chemical composition is controlled by many factors including host rock lithology, temperature-pressure conditions, fluid pathways in the subsurface, water-to-rock ratio, phase separation, phase segregation, and magmatic degassing. As the fluids discharge from the hydrothermal system due to cooling and mixing with cold seawater, metals dissolved in the fluids precipitate as sulfide minerals, or in increasingly oxygenated environment as sulfates and oxides and are partly released into the water column via the hydrothermal plume in both dissolved and particulate form. Not only are hydrothermal fluids enriched in many metals, but they have also distinct dissolved organic matter (DOM) composition from background seawater. DOM containing metal-binding functional groups such as hydroxide (-OH-), thiol (-SH-) or amino (NH2) groups are known to play an important role for metal solubility, transport and consequences for mineral precipitation.
While complex organic molecules cannot exist in hot (ca. >250°C) hydrothermal fluids, DOM molecules such as amino acids or proteins could still play an important role for forming stable complexes with hydrothermally derived metals in the early mixing plume or lower-temperature fluids. The presence of significantly elevated amino acid concentrations in hydrothermal fluids (even at rather high temperatures) implies that they are available as potential complexing agents for metals, possibly influencing their bioavailability and solubility. Within my PhD project, I want to study the molecular complexity of metal-organic ligands occurring in deep sea and shallow hydrothermal vent systems in collaboration with Prof. Thorsten Dittmar’s group at the ICBM of the University of Oldenburg, with a focus on trace metals such as iron (Fe) and copper (Cu). Before I started my PhD at the working group of Prof. Andrea Koschinsky, I have completed the master’s degree in “Marine Environemental Sciences” at the University of Oldenburg in the working group of Prof. Thorsten Dittmar. I have worked extensively with high pressure-temperature experimentation in my master thesis, where I investigated dissolved organic carbon transformation and cycling via radiocarbon measurements in hydrothermal environments simulating deep ocean hot spring conditions. The thesis is entitled “Hydrothermal transformation of dissolved organic matter – a radiocarbon and molecular study using AMS and FT-ICR-MS”.
During my PhD I’m not only comparing natural samples from vent systems of two upcoming cruises with a wide variety of parameters influencing the complexes, I also want to conduct autoclave experiments at the University of Bremen in the Working Group of Prof. Dr. Wolfgang Bach to investigate complexing or degradation influenced processes of metal-organic ligands by adjusting temperature, pressure and host-rock effects and their insights to the molecular composition of the complexing organics. The natural samples for the project originate from the cruises in 2023 to Atlantic mid-ocean ridge hydrothermal systems (M190) and shallow and deep-sea hydrothermal systems in the Mediterranean Sea close to Milos (M192).
Publications:
Diehl, A., Anagnostou, E., Monien, P., Pape, T., Meckel, E.M., Römer, M., Mezri, L., Bach, W., Monien, D., Hansen, C. and Röhler, A., 2026. High H2 production in sediment-hosted hydrothermal fluids at an ultraslow spreading mid-ocean ridge. Communications Earth & Environment, 7(1), p.12. https://doi.org/10.1038/s43247-025-02962-2
Ongoing projects:
2025
M210 – Dive@MAR 2: Distribution of hydrthermal vents along the Mid-Atlantic Ridge (29-38° N) and implications for hydrothermal exchange and hydrothermal ecosystems: Part 2
PhD Student (Research Associate), Sampling hydrothermal fluids and on-board chemical analyses and sample conservation for inorganic and organic geochemical analyses
Links:
https://www.marum.de/M210.html
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2024
MSM131 – Jøtul Hydrothermal Field: Magma-Sediment Interaction at the Ultraslow-Spreading Knipovich Ridge
PhD Student (Research Associate), Sampling hydrothermal fluids and on-board chemical analyses and sample conservation for inorganic and organic geochemical analyses
Links:
https://www.marum.de/MSM131.html
https://www.marum.de/Erste-Ergebnisse-der-Forschungsfahrt-MSM131.html
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2023
DOME (SPP2238) – Dynamics of Ore Metals Enrichment
PhD Student (Research Associate), The role of p-T conditions, host rock lithology, phase separation, and organic compounds on metal mobility and metal sulfide deposition in spatially resolved hydrothermal vent areas. DFG Special Priority Programme “Dynamics of Ore Metals Enrichment “– DOME (SPP 2238) under the supervision of Prof. Dr. Andrea Koschinsky
Links:
https://andrea-koschinsky.org/research-projects/dome/
https://www.uni-potsdam.de/en/spp2238/meetings-and-workshops/dome-meetings
M192 BridgeHell – Bridging hydrothermal sites along the Hellenic Arc off Milos from shallow to deep
PhD Student (Research Associate), Sampling hydrothermal fluids and on-bord chemical analyses and sample conservation for inorganic and organic geochemical analyses
Links:
https://andrea-koschinsky.org/research-projects/m192-bridgehell/
https://www.marum.de/Dr.-solveig-bhring/M-192.html
M190 Dive@MAR – Distribution of Venting Along the Mid-Atlantic Ridge (29–38°N) and Implications for Hydrothermal Exchange and Vent Ecosystems
PhD Student (Research Associate), Sampling hydrothermal fluids and on-board chemical analyses and sample conservation for inorganic and organic geochemical analyses
Links:
https://andrea-koschinsky.org/research-projects/m190-dive-mar/
Find a Blog (in German) from Prof. Harald Strauß here:
https://strauss2023.uni-muenster.blog/
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Participation in previous projects
2021
Alkor AL557 – Carbostore
Research assistant for Dr. Michael Seidel (ICBM, https://uol.de/en/icbm/marine-geochemistry/staff/dr-michael-seidel) and Prof. Dr. Thorsten Dittmar (ICBM, https://uol.de/en/icbm/marine-geochemistry/staff/prof-dr-thorsten-dittmar), Sampling CTD and MUC porewaters for DOM analyses
Link:
https://www.carbostore.de/102583/index.php.de
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2019
Kronprins Haakon – HACON project – Hot vents in an ice-covered ocean
Research student with Dr. Eoghan Reeves (University of Bergen, https://www.uib.no/en/persons/Eoghan.P..Reeves), Sampling hydrothermal fluids and on-bord chemical analyses
Link:
https://haconfrinatek.wordpress.com/2019/11/04/deep-vents-under-ice/
G.O. Sars – Annual summer cruise to Norwegian marine territory
Research student with Dr. Eoghan Reeves (University of Bergen, https://www.uib.no/en/persons/Eoghan.P..Reeves), Sampling hydrothermal fluids and on-bord chemical analyses
Link: