Investigating the seafloor as a reactor

The seafloor represents the key interface between the oceans and the ocean crust. Driven by steep geothermal gradients, major geochemical mass and heat transfer occurs as seawater circulates through the crust and participates in metasomatic water-rock reactions. Abundant heat, reduced chemicals and reworked carbon substrate fuel unique biological communities at hydrothermal vents, an environment considered a likely contender for the origin of life on earth. But the impact of this seafloor reactor on the global carbon cycle, the global climate, the long-term evolution of ocean chemistry and the diversity of life is still poorly constraint, let alone properly quantified. In an integrated approach, we will use samples and data acquired from natural systems and experiments conducted under precisely controlled conditions as well as coupled thermodynamic-kinetic models to further elucidate these processes.

The emphasis in this project lies on using batch and flow-through experiments to investigate a variety of different processes that occur within marine hydrothermal systems. (Hydrothermal Lab)

A selection of studied processes with associated collaborators:

• Modes of hydrocarbon gas generation in hydrothermal sediments (M. Song, F. Schubotz, W.Bach)
• Fractionation of Si isotopes during serpentinization (S. Geilert, E. Albers)
• Investigation of S syn- and disproportionation in hydrothermal systems (V. Kürzinger, W. Bach)
• Development of bio-textures through basalt glass alteration (A. Türke, S. Jørgensen)
• Interaction of Fe-rich hydrothermal solutions with calcite lithologies (W.Bach)
• Changes imposed on DOM radiocarbon signature and molecular characteristics during hydrothermal alteration (E.-M. Meckel, H. Grotheer, T. Dittmar)
• DOM related formation of metal binding ligands and its impact on microbial community structure in hydrothermal plumes (C. Kleint, A. Koschinsky, M. Perner, T. Dittmar)
• Molecular diversity of DOM in hydrothermal systems of the Kermadec Arc (SO253), the Mid-Atlantic Ridge (M176) and Surtsey (SUSTAIN – Surtsey drilling project) (A. Türke, T. Dittmar)

Contacts: Christian Hansen, Wolfgang Bach

Exemplary procedure of a Dickson-type batch experiment: