Holocene Cyclic Records of Ice-Rafted Debris and Sea Ice Variations on the East Greenland and Northwest Iceland Margins

The dynamics of the Greenland Ice Sheet and drift of sea ice from the Arctic Ocean reaching Denmark Strait are poorly constrained. We present data on the provenance of Fe oxide detrital grains from two cores in the Denmark Strait area and compare the Fe grain source data with other environmental proxies in order to document the variations and potential periodicities in ice-rafted debris delivery during the Holocene. Based on their Fe grain geochemistry, the sediments can be traced to East Greenland sources and to more distal sites around the Arctic Basin. On the Holocene time scales of the two cores, sea ice biomarker (IP25) data, and quartz weight percent reveal positive associations with T°C and inverse associations with biogenic carbonate wt%. Trends in the data were obtained from Singular Spectrum Analysis (SSA), and residuals were tested for cyclicity. Trends on the environmental proxies explained between 15 and 90% of the variance. At both sites the primary Fe grain sources were from Greenland, but significant contributions were also noted from Banks Island and Svalbard. There is a prominent cyclicity of 800 yrs as well as other less prominent cycles for both Greenland and arctic sources. The Fe grain sources from Greenland and the circum-Arctic Ocean are in synchronization, suggesting that the forcings for these cycles are regional and not local ice sheet instabilities

Macrobicyclic lanthanide cryptates

Das Ziel dieser Arbeit war die Modifikation von tris(bipyridin)-basierten Kryptanden, um das besondere Potential dieser Ligandenklasse für innovative Anwendungen mit dreiwertigen Lanthanoidionen zu nutzen. Im ersten Teil wurden deuterierte und funktionalisierte Derivate dieser Verbindungen dargestellt und anschließend an ausgewählte Biomoleküle konjugiert. In anschließenden massenspektrometrischen Quantifizierungsanwendungen wurde so die relative Quantifizierung ganzer Proteine sowie die absolute Quantifizierung einzelner Peptide ermöglicht. Der zweite Teil befasst sich mit dem Design und der Synthese von binuklearen Lanthanoidkryptaten, in die zwei unterschiedliche Lanthanoidionen selektiv eingebracht werden konnten. Im letzten Teil wurden bipyridin-basierte Chelatoren verwendet, welche die stabilen Isotope $^2$H, $^{13}$C und/oder $^{18}$O enthalten. Anhand der daraus synthetisierten Lanthanoidkomplexe wurden die Lumineszenzeigenschaften ausgewählter Lanthanoide weiter optimiert bzw. untersucht

Organic carbon, carbonate, and clay mineral distributions in eastern central Arctic Ocean surface sediments

Results from a detailed sedimentological investigation of surface sediments from the eastern Arctic Ocean indicate that the distribution of different types of sediment facies is controlled by different environmental processes such as sea-ice distribution, terrigenous sediment supply, oceanic currents, and surface-water productivity.In comparison to other open-ocean environments, total organic carbon contents are high, with maximum values in some deep-basin areas as well as west and north of Svalbard. In general, the organic carbon fraction is dominated by terrigenous material as indicated by low hydrogen index values and high C/N ratios, probably transported by currents and/or sea ice from the Eurasian Shelf areas. The amount of marine organic carbon is of secondary importance reflecting the low-productivity environment described for the modern ice-covered Arctic Ocean. In the area north of Svalbard, some higher amounts of marine organic matter may indicate increased surface-water productivity controlled by the inflow of the warm Westspitsbergen Current (WSC) into the Arctic Ocean and reduced sea-ice cover. This influence of the WSC is also supported by the high content of biogenic carbonate recorded in the Yermak Plateau area.The clay mineral distribution gives information about different source areas and transport mechanisms. Illite, the dominant clay mineral in the eastern central Arctic Ocean sediments, reaches maximum values in the Morris-Jesup-Rise area and around Svalbard, indicating North Greenland and Svalbard to be most probable source areas. Kaolinite reaches maximum values in the Nansen Basin, east of Svalbard, and in the Barents Sea. Possible source areas are Mesozoic sediments in the Barents Sea (and Franz-Josef-Land). In contrast to the high smectite values determined in sea-ice samples, smectite contents are generally very low in the underlying surface sediments suggesting that the supply by sea ice is not the dominant mechanism for clay accumulation in the studied area of the modern central Arctic Ocean