Pore water chemistry of sediment core GeoB15101-7 and water chemistry of CTD casts GeoB15101-1 and GeoB15101-6

Submarine brine lakes feature sharp and persistent concentration gradients between seawater and brine, though these should be smoothed out by free diffusion in open ocean settings. The anoxic Urania basin of the Eastern Mediterranean contains an ultra sulfidic, hypersaline brine of Messinian origin above a thick layer of suspended sediments. With a dual modeling approach we reconstruct its contemporary stratification by geochemical solute transport fundamentals, and show that thermal convection is required to maintain mixing in the brine and mud layer. The origin of the Urania basin stratification was dated to 1650 years before present, which may be linked to a major earthquake in the region. The persistence of the chemoclines may be key to the development of diverse and specialized microbial communities. Ongoing thermal convection in the fluid mud layer may have important, yet unresolved consequences for sedimentological and geochemical processes, also in similar environments.

Non-isoprenoidal intact polar lipids, isoprenoidal and non-isoprenoidal core lipids, isoprenoidal intact polar lipids of the Black Sea site GeoB15105 sampled during Meteor cruise M84/1 in February 2011

This PhD thesis focused on the analysis and application of microbial membrane lipids as biomarkers in marine sediments. Existing protocols for lipid extraction from marine sediments and biomass were modified. In addition, recent protocols based on high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) as well as state-of-the-art mass spectrometric analysis by quadrupole time-of-flight (MSqTOF) and the triple quadrupole (MSQQQ) mass spectrometer were used to investigate matrix effects and evaluate the reliability of quantitative analysis in marine environmental samples. The improved lipid extraction and quantification were used to analyze Black Sea water column and sediments samples to a depth of 8 meters from site GeoB 15105 taken during cruise M84/1 (DARCSEAS) with R/V Meteor to apply lipid analysis in benthic bio systems. With this component specific differentiation between planktonic and benthic lipid signature we assessed possible lipid sources. Here, this high detail lipid fingerprinting allowed us to observe changes in the head group and lipid core structures of the intact polar lipids according to the geochemical zonation.