Martin Butzin

Alkenone temperature anomalies in the Brazil-Malvinas Confluence area caused by lateral advection of suspended particulate material

Alkenone temperatures derived from suspended particulate organic material which was collected in austral summer 2001 from surface waters (5 m) south of the Brazil-Malvinas Confluence deviate from measured temperatures by −4° to −7°C when UK′37 ratios are converted to temperature using the Muller et al. (1998) calibration and up to −3°C when using the calibration of Conte et al. (2006). In contrast, alkenone temperatures determined from particulate material sampled north of the confluence reveal close correspondence to in situ temperatures or show slightly higher values. We suggest that the southern samples are biased by suspended organic detritus originating from the cold subpolar waters of the northward flowing Malvinas Current, whereas the northern samples carry an UK′37 signal of tropical/subtropical origin, transported southward with the Brazil Current. On the basis of surface ocean transport pathways and velocities simulated with the large-scale geostrophic (LSG) ocean general circulation model, we identify areas of the world ocean where alkenone temperatures are potentially biased to higher or lower values due to long particle residence times and lateral advection by surface currents.

Implications for chloro- and pheopigment synthesis and preservation from combined compound-specific 13 C, 15 N, and 1 14 C analysis

Chloropigments and their derivative pheopigments preserved in sediments can directly be linked to photosynthesis. Their carbon and nitrogen stable isotopic compositions have been shown to be a good recorder of recent and past surface ocean environmental conditions tracing the carbon and nitrogen sources and dominant assimilation processes of the phytoplanktonic community. In this study we report results from combined compound-specific radiocarbon and stable carbon and nitrogen isotope analysis to examine the time-scales of synthesis and fate of chlorophylla and its degradation products pheophytina, pyropheophytina, and 132,173-cyclopheophorbidea-enol until burial in Black Sea core-top sediments. The pigments are mainly of marine phytoplanktonic origin as implied by their stable isotopic compositions. Pigment δ15N values indicate nitrate as the major uptake substrate but 15N-depletion towards the open marine setting indicates either contribution from N 2-fixation or direct uptake of ammonium from deeper waters. Radiocarbon concentrations translate into minimum and maximum pigment ages of approximately 40 to 1200 years. This implies that protective mechanisms against decomposition such as association with minerals, storage in deltaic anoxic environments, or eutrophication-induced hypoxia and light limitation are much more efficient than previously thought. Correspondence to: S. Kusch (stephanie.kusch@awi.de) Moreover, seasonal variations of nutrient source, growth period, and habitat and their associated isotopic variability are likely at least as strong as long-term trends. Combined triple isotope analysis of sedimentary chlorophyll and its primary derivatives is a powerful tool to delineate biogeochemical and diagenetic processes in the surface water and sediments, and to assess their precise time-scales.

Implications for chloro- and pheopigment synthesis and preservation from combined compound-specific δ 13 C, δ 15 N, and Δ 14 C analysis

Chloropigments and their derivative pheopig- ments preserved in sediments can directly be linked to pho- tosynthesis. Their carbon and nitrogen stable isotopic com- positions have been shown to be a good recorder of recent and past surface ocean environmental conditions tracing the carbon and nitrogen sources and dominant assimilation pro- cesses of the phytoplanktonic community. In this study we report results from combined compound-specific radiocar- bon and stable carbon and nitrogen isotope analysis to exam- ine the time-scales of synthesis and fate of chlorophyll-a and its degradation products pheophytin-a, pyropheophytin-a, and 13 2 ,17 3 -cyclopheophorbide-a-enol until burial in Black Sea core-top sediments. The pigments are mainly of ma- rine phytoplanktonic origin as implied by their stable isotopic compositions. Pigment 15 N values indicate nitrate as the major uptake substrate but 15 N-depletion towards the open marine setting indicates either contribution from N 2-fixation or direct uptake of ammonium from deeper waters. Ra- diocarbon concentrations translate into minimum and max- imum pigment ages of approximately 40 to 1200 years. This implies that protective mechanisms against decomposition such as association with minerals, storage in deltaic anoxic environments, or eutrophication-induced hypoxia and light limitation are much more efficient than previously thought.

Marine Radiocarbon Reservoir Age Simulations for the Past 50,000 Years

We present simulations of marine radiocarbon reservoir ages using the ocean general circulation model LSG- HAMOCC2s, and evaluate the results with Marine13 raw data records. Our model considers various climatic background states. Radiocarbon cycle boundary conditions are atmospheric ∆14C values according to IntCal13, a recent atmospheric CO2 reconstruction, and spatially variable concentrations of dissolved inorganic carbon derived from marine carbon cycle simulations. Our model reasonably agrees with glacial marine ∆14C records but indicates reservoir ages varying with time, different to the invariant reservoir age corrections applied to the observations and to Marine13. Modelled global-mean reservoir ages are in the range 400–800 years compared to the invariant Marine13 value of 405 years. Self-consistent simulations involving the Cariaco Basin record (which is the most continuous marine record contributing to IntCal13 for periods prior to about 30 kyears) amplify the temporal reservoir age variability with global-mean values of about 350–850 years, and improve the agreement with ∆14C observations in some areas.

Oceanic d18O Variation and its Relation to Salinity in the MPI-OM Ocean Model

Post-graduate education in Germany has changed a lot over the past decades. Formerly, PhD students generally did not have the option to attend formal classes and lectures and were expected to conduct their independent research, including occasionally teaching courses for students. Since the introduction of bachelor and masters studies with the Bologna Process in the late 90th, the higher education in Europe has been harmonized, leading to more structured and focused studies at the expense of a broad and universal disciplinary education. At this same time, special fields such as Earth System Science became more interdisciplinary. In consequence, universities and research institutes have established so-called research schools and/or graduate schools, offering specific courses and training alongside the doctorate. Especially, Earth System Science has developed from an interesting concept in Earth Sciences education to a fully integrative Science focussed on understanding the complex system Earth. This evolution is partially due to the radical and far reaching anthropogenic changes and the general feeling of helplessness with regards to the possible consequences and future impacts on the Earth System. The Helmholtz “Earth System Science Research School” (ESSReS) is a small unit of PhD students co-organized by three educational and research institutions in the city state Bremen: University of Bremen (Institute for Environmental Physics, IUP), Jacobs University (School of Engineering and Science (JU)), and Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research in Bremerhaven (AWI). ESSReS aims at the integration of research at the interface of Geology, Biology, Physics, Geophysics, Mathematics and Informatics. It is therefore multi- and interdisciplinary in every aspect. The training, curriculum, and PhD research subjects are closely located at the interfaces between the participating disciplines. This is guaranteed by interdisciplinary supervision of the PhD project. The long-term goal of ESSReS is not only to enhance exchange and interaction between these disciplines, but to enforce a newly integrated concept, where separation between disciplines becomes more and more obsolete. Now, at the end of two three-years terms of PhD student education it can be stated that ESSReS provide a solid base for a new generation of excellent scientists in Earth and Environmental Sciences.Information about past environmental conditions is preserved in the elemental signature of biogenic marine carbonates. Thus, trace element to calcium ratios (Me/Ca) of biogenic calcium carbonates, such as bivalve shells, are often used to reconstruct past environmental conditions at the time of carbonate formation (Foster et al., 2008). In this study, we examine the suitability of the long-lived (> 400 years) bivalve Arctica islandica as a high-resolution bioarchive by measuring Me/Ca ratios in the shell carbonate. Pb/Ca concentrations in A. islandica shells reflect anthropogenic gasoline lead consumption and further provide a centennial record of lead pollution for the collection site off the coast of Virginia, USA. With A. islandica shells from the North Sea we test the hypothesis that Ba/Ca and Mn/Ca ratios are indicators of the diatom abundance. Our results indicate that statistically both ratios correlate well with the diatom abundance, and yet, on a year-to-year base, there is no consistent reflection of diatom abundance patterns in the Ba/Ca and Mn/Ca annual profiles. These findings indicate that primary production affects Ba/Ca and Mn/Ca shell ratios, though we suggest that both elements are coupled to primary production through different processes and are affected by further, yet unknown processes.To date, the software package SCIATRAN (Rozanov et al. 2002; Rozanov et al., 2005, 2008) has been used for modelling radiative processes in the atmosphere for the retrieval of trace gases from satellite data from the satellite sensor SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY onboard the satellite ENVISAT). This SCIATRAN version only accounted for radiative transfer within the atmosphere and reflection of light at the earth surface. However, radiation also passes the air-water interface, proceeds within the water and is modified by the water itself and the water constituents. Therefore, SCIATRAN has been extended by oceanic radiative transfer and coupling it to the atmospheric radiative transfer model under the terms of established models for radiative transfer underwater (Kopelevich 1983; Morel et al. 1974, 2001; Shifrin 1988; Buitevald et al. 1994; Cox and Munk 1954a, 1954b; Breon and Henriot 2006; Mobley 1994) and extending the data bases to include the specific properties of the water constituents (Pope and Fry 1997; Haltrin 2006; Prieur and Sathyendranath 1981).