Blar i forfatter "Lehmann, Moritz F."

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    • Effects of low oxygen concentrations on aerobic methane oxidation in seasonally hypoxic coastal waters 

      Steinle, Lea; Maltby, Johanna; Treude, Tina; Kock, Annette; Bange, Hermann W.; Engbersen, Nadine; Zopfi, Jakob; Lehmann, Moritz F.; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-29)
      Coastal seas may account for more than 75 % of global oceanic methane emissions. There, methane is mainly produced microbially in anoxic sediments from which it can escape to the overlying water column. Aerobic methane oxidation (MOx) in the water column acts as a biological filter, reducing the amount of methane that eventually evades to the atmosphere. The efficiency of the MOx filter is potentially ...

    • Fracture-controlled fluid transport supports microbial methane-oxidizing communities at Vestnesa Ridge 

      Yao, Haoyi; Hong, Wei-Li; Panieri, Giuliana; Sauer, Simone; Torres, Marta E.; Lehmann, Moritz F.; Gründger, Friederike; Niemann, Helge (Journal article; Peer reviewed, 2019-05-29)
      We report a rare observation of a mini-fracture in near-surface sediments (30 cm below the seafloor) visualized using a rotational scanning X-ray of a core recovered from the Lomvi pockmark, Vestnesa Ridge, west of Svalbard (1200 m water depth). Porewater geochemistry and lipid biomarker signatures revealed clear differences in the geochemical and biogeochemical regimes of this core compared with ...

    • Life on the edge: Active microbial communities in the Kryos MgCl2-brine basin at very low water activity 

      Steinle, Lea; Knittel, Katrin; Felber, Nicole; Casalino, Claudia; de Lange, Gert; Tessarolo, Chiara; Stadnitskaia, Alina; Sinninghe Damsté, Jaap S.; Zopfi, Jakob; Lehmann, Moritz F.; Treude, Tina (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-17)
      The Kryos Basin is a deep-sea hypersaline anoxic basin (DHAB) located in the Eastern Mediterranean Sea (34.98°N 22.04°E). It is filled with brine of re-dissolved Messinian evaporites and is nearly saturated with MgCl<sub>2</sub>-equivalents, which makes this habitat extremely challenging for life. The strong density difference between the anoxic brine and the overlying oxic Mediterranean seawater ...

    • Redox-dependent niche differentiation provides evidence for multiple bacterial sources of glycerol tetraether lipids in lakes 

      Weber, Yuki; Sinninghe Damsté, Jaap S.; Zopfi, Jakob; De Jonge, Cindy; Gilli, Adrian; Schubert, Carsten J.; Lepori, Fabio; Lehmann, Moritz F.; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-10-23)
      Terrestrial paleoclimate archives such as lake sediments are essential for our understanding of the continental climate system and for the modeling of future climate scenarios. However, quantitative proxies for the determination of paleotemperatures are sparse. The relative abundances of certain bacterial lipids, i.e., branched glycerol dialkyl glycerol tetraethers (brGDGTs), respond to changes in ...

    • Reduced methane seepage from Arctic sediments during cold bottom-water conditions 

      Ferré, Benedicte; Jansson, Pär; Moser, Manuel; Serov, Pavel; Portnov, Aleksei D; Graves, Carolyn; Panieri, Giuliana; Gründger, Friederike; Berndt, Christian; Lehmann, Moritz F.; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-13)
      Large amounts of methane are trapped within gas hydrate in subseabed sediments in the Arctic Ocean, and bottom-water warming may induce the release of methane from the seafloor. Yet the effect of seasonal temperature variations on methane seepage activity remains unknown as surveys in Arctic seas are conducted mainly in summer. Here we compare the activity of cold seeps along the gas hydrate stability ...

    • Water column methanotrophy controlled by a rapid oceanographic switch 

      Steinle, Lea; Graves, Carolyn A.; Treude, Tina; Ferré, Benedicte; Biastoch, Arne; Bussmann, Ingeborg; Berndt, Christian; Krastel, Sebastian; James, Rachel H.; Behrens, Erik; Böning, Claus W.; Greinert, Jens; Sapart, Célia-Julia; Scheinert, Markus; Sommer, Stefan; Lehmann, Moritz F.; Niemann, Helge (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-04-20)
      Large amounts of the greenhouse gas methane are released from the seabed to the water column, where it may be consumed by aerobic methanotrophic bacteria. The size and activity of methanotrophic communities, which determine the amount of methane consumed in the water column, are thought to be mainly controlled by nutrient and redox dynamics. Here, we report repeated measurements of methanotrophic ...