Muhammed Fatih Sert

Title of the PhD thesis:

"Biogeochemistry of dissolved organic matter in Arctic Ocean waters charged with methane"

Abstract:

Dissolved organic matter (DOM) is defined as organic matter that is smaller than a nominal pore size filter (e.g., 0.7 µm) that passes through during the filtration of aquatic samples. It comprises the largest reservoir of reduced carbon (700 Pg C) in the oceans. The DOM pool is in close interaction with all the elemental cycles and food chains in the ocean and is an essential component in the marine microbial loop. Methane is seeping from numerous geological sources in the Arctic Ocean associated with multiple mechanisms that elevate methane production and release. Independent of the mechanism, however, liberated methane is predominantly consumed in the water column by methanotrophic bacteria (MOB), which use methane as a source of carbon and energy during an aerobic enzymatic reaction called methane oxidation (MOx). In sedimentary fluid flow systems such as cold seeps or hydrothermal vents, the amount of methane release and subsequent MOx would be substantial and further trigger other ecosystem processes such as bacterial growth and heterotrophic consumption and consequent mechanisms that alter DOM composition in the water column. Since methane is one of the most potent greenhouse gasses in the atmosphere and due to its subsequent effect on global warming, it has been quantified extensively in the oceanic environments and its fate in the water column has been investigated in different types of geological settings. However, the effects of methane emanation and methane-driven processes on DOM dynamics in the water column have been merely constrained. The main objective of this thesis was to unravel the modifications of DOM composition in relation to methane release in the Arctic Ocean cold seeps and hydrothermal vents.

The thesis is published and available in Munin

Supervisors

• Researcher Dr. Anna Silyakova, Department of Geosciences, UiT (main supervisor)
• Researcher Dr. Friederike Gründger, Department of Biology, Aarhus University, Denmark
• Professor Helge Niemann, NIOZ Royal Institute for Sea Research, the Netherlands

Evaluation committee

• Professor Thorsten Dittmar, ICBM, Universität Oldenburg, Germany (1. opponent)
• Dr Jeffrey Hawkes, Department of Chemistry, University of Uppsala, Sweden (2. Opponent)
• Professor Giuliana Panieri, Department of Geosciences, UiT (internal member and leader of the
  committee)

Links to the trial lecture and defense will be possible to open when the live stream begins. If you haven`t clicked the link to the folder before it begins, refresh the web browser for them to become visible. If you have clicked the link to the trial lecture or defense before it has started, it will open automatically when the stream begins. 

The trial lecture starts at 10.15 November 25th

Trial lecture

The defense starts at 12.15 November 25th

Defense