Description: Summary The Bathymetrists Seamounts (BSM) are located north of the volcanic Sierra Leone Rise in the eastern Atlantic between 6° and 9°N. The three W-E, N-S and NE-SW striking directions of the seamounts indicate a clear structural control for the emplacement of these volcanoes. The origin of the melts, their relationship to the Sierra Leone Rise and the role of the faults in the formation of the melts are unknown as the BSM could be explained by plume related volcanism or decompression melting beneath deep (transform) faults. The SEDIS-cruise M152/2 of RV METEOR strove for a better understanding of the life cycle of submarine volcanoes and their effect on the oceanic lithosphere in the oceanic intraplate setting of the BSM and the relationship to the Sierra Leone Rise. The aims were: 1) to understand the interaction between crustal thickness, tectonics and volcanic phases, 2) to investigate the structural, chronological and petrological evolution of individual seamounts and seamount chains, 3) to review slope failures and resulting mass flow processes. We addressed these objectives by more than 4000 km highresolution reflection seismic and more than 5000 km of parametric echosounder, multi-beam, and gravity and magnetic profiles. Rock samples for ground truthing and geochemical research have been collected during 14 dredge stations. We further determined the concentrations in surface seawater and air and the state of air-sea exchange of a number of nowadays globally banned pesticides, polychlorinated biphenyls, brominated flame retardants, polycyclic aromatic hydrocarbons and their derivatives. Zusammenfassung Die Bathymetrists Seeberge liegen nördlich der Sierra Leone Schwelle, einer vulkanischen Plattform im östlichen Atlantik zwischen 6° und 9° N. Diese submarinen Vulkane gruppieren sich entlang W-E, N-S und NE-SW Trends, was eine strukturelle Kontrolle der Vulkanentstehung indiziert. Die Schmelzentstehung sind unbekannt und können mit PlumeVulkanismus oder Dekompressionsschmelzen unter bisher nicht untersuchten Störungen und tiefen Transformstörungen zusammenhängen. Der Bezug zur Sierra Leone Schwelle ist ebenfalls unbekannt. Im Zuge der SEDIS-Expedition M152/2 mit FS METEOR wurde der Lebenszyklus von Unterwasservulkanen und deren geochemischen Einfluss auf die ozeanische Lithosphäre der Bathymetrists Seeberge untersucht. Anhand der profilhaften geophysikalischer Messungen und Dredge-Proben wollen wir 1) die Wechselwirkung zwischen Krustenmächtigkeit, Tektonik und Vulkanismus verstehen, 2) die strukturelle, chronologische und petrologische Entwicklung von Vulkanen und Vulkanketten untersuchen, und 3) Auslösemechanismen, Transportprozesse und Volumina von Hangrutschungen studieren. Zur Bearbeitung der wissenschaftlichen Fragen sammelten wir mehr als 4000 km mehrkanal-reflexionsseismischer und mehr als 5000 km parametrische Sedimentecholot, Fächerlot, Schwere und Magnetik-Profile. Für die geochemischen Arbeiten sammelten wir an 14 Stationen Gesteinsproben unter Einsatz einer Dredge. Die regelmäßige Beprobung der Luft und des Oberflächenwassers diente der Bestimmung der Konzentration von heute weltweit verbotenen Pestiziden, polychlorierten Biphenylen, bromierten Flammschutzmitteln, polyzyklischen aromatischen Kohlenwasserstoffen und deren Derivaten und um den Austausch zwischen Luft und Meer weiter zu verstehen.

Description: The main goal of cruise MSM61 was to install an autonomous multidisciplinary observatory at the summit of Senghor Seamount off the Cape Verdean archipelago. A suite of different mobile and moored instrument platforms equipped with physical, biological and biogeochemical instruments was deployed during the cruise in order to investigate spatio-temporal variability of physical and biogeochemical conditions and how these affect the local ecosystem at this openocean seamount. The research program further included hydrographic work, biological and biogeochemical sampling as well as video transects in the meso- and bathypelagic zones both at Senghor Seamount and at the Cape Verde Ocean Observatory (CVOO).

Description: Rio Grande Rise: microcontinent, mantle plume, or both? The origin of the Rio Grande Rise (RGR) is debated. It could represent a continental sliver, or a large igneous province that was emplaced in the late Cretaceous after the opening of the South Atlantic Ocean. The interplay between the RGR and the nearby Jean Charcot Seamount Chain (JCSC) is also not understood. Cruise MSM82 dredge sampled rocks from the JCSC and the RGR and measured two seismic refraction profiles across the RGR where it is bisected by a long rift graben. A range of geophysical data were also collected during much of the expedition, including magnetics, gravity, bathymetry (Kongsberg EM 122), sub-bottom profiling (ATLAS PARASOUND DS P70) and ADCP data. The combination of geochronological, geochemical and geophysical information will provide a unique window on the relation between mantle plumes, continental fragments and the evolution of large igneous provinces.

Description: The coastal and open oceans represent a major, but yet unconstrained, sink for plastics. It is likely that plastic-biota interactions are a key driver for the fragmentation, aggregation, and vertical transport of plastic litter from surface waters to sedimentary sinks. Cruise SO279 conducted sampling to address core questions of microplastic distribution in the open ocean water column, biota, and sediments. Seven stations were sampled between the outer Bay of Biscay and the primary working area south of the Azores. Additional samples were collected from surface waters along the cruise track to link European coastal and shelf waters with the open ocean gyre. Microplastic samples coupled with geochemical tracer analyses will build a mechanistic understanding of MP transport and its biological impact reaching from coastal seas to the central gyre water column and sinks at the seabed. Furthermore, floating plastics were sampled for microbial community and genetic analyses to investigate potential enzymatic degradation pathways. Cruise SO279 served as the third cruise of a number of connected research cruises to build an understanding of the transport pathways of plastic and microplastic debris in the North Atlantic from the input through rivers and air across coastal seas into the accumulation spots in the North Atlantic gyre and the vertical export to its sink at the seabed. The cruise was an international effort as part of the JPI Oceans project HOTMIC (“HOrizontal and vertical oceanic distribution, Transport, and impact of MICroplastics”) and the BMBF funded project PLASTISEA (‘Harvesting the marine Plastisphere for novel cleaning concepts’), and formed a joint effort of HOTMIC and PLASTISEA researchers from a range of countries and institutes.

Description: The oxygen minimum zone (OMZ) in the eastern tropical South Pacific Ocean is tightly connected to the coastal upwelling system off Peru. The high biological productivity off Peru is therefore, driven by the complex interplay between the amount of nutrients recycled by remineralisation processes in the OMZ and the upwelling which brings these nutrients to the surface layer. However, surprisingly little is known about organic matter cycling and its effects on biogeochemical processes in the OMZ off Peru. To this end we conducted a first comprehensive study on the role of organic matter for the biogeochemical processes and the maintenance of the OMZ off Peru. M138 combined measurements of marine biogeochemistry, microbiology, physical oceanography and air chemistry with foci on (i) the efficiency of the biological pump, (ii) the nitrogen cycle processes in the OMZ, (iii) the ventilation of the OMZ as well as (iv) the air/sea gas exchange across the ocean/atmosphere interface and (v) aerosol deposition. The METEOR cruise M138 was performed as part of the third phase of the SFB754 'Climate-Biogeochemistry Interactions in the Tropical Ocean' (www.sfb754.de).