Glendonites are pseudomorphs after the mineral ikaite (CaCO3 x 6H2O) and composed of calcite (CaCO3). In the past, they have been used as a paleo-thermometer because the primary mineral ikaite, according to observations and experiments, seems to be formed at temperatures near freezing, high alkalinity and high phosphate concentrations in marine sediments. An enigmatic occurrence of the largest glendonites known world-wide, in the Early Eocene Fur Formation of northwestern Denmark offers the unique possibility to shed more light on the actual mechanism and controlling parameters of ikaite formation. Right in the aftermath of the Paleocene-Eocene thermal maximum, a time known for its global pertubation in the global carbon cycle, the formation of authigenic calcium carbonate concretions start in the Fur Formation. In a specific stratigraphic interval inbetween these concretions, the glendonites can be found. We will investigate if termperature changes or changes in geochemical parameters of the Danish Basin caused the sudden formation of ikaite during a time interval that was based on known paleoclimatic reconstructions (semi tropic) not favorable for ikaite formation.
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Business Improvement Districts (BID), die in Hamburg Innovationsbereiche genannt werden, sind klar begrenzte Geschäftsgebiete (Business Districts), in denen auf Veranlassung der Betroffenen (z. B. Eigentümerschaft und Gewerbetreibenden) in einem festgelegten Zeitraum (maximal 8 Jahre) in Eigenorganisation Maßnahmen zur Quartiersaufwertung (Improvement) durchgeführt werden. Ein Ziel dabei ist es, durch die Schaffung eines Innovationsbereichs die Attraktivität eines Einzelhandels-, Dienstleistungs- und Gewerbezentrums für Kunden, Besucherinnen und Besucher zu erhöhen. Finanziert werden BIDs durch eine kommunale Abgabe, die alle im Gebiet ansässigen Grundeigentümerinnen und Grundeigentümer zu leisten haben.
This project focuses on the long-term stability (or otherwise) of vegetation, based on a series of multi-proxy records in southern South America. We will build a network of sites suitable for high-resolution reconstructions of changes in vegetation since the Last Glacial Maximum, and use these to test a null hypothesis that changes in vegetation over the past 14,000 years are driven by internal dynamics rather than external forcing factors. The extent to which the null hypothesis can be falsified will reveal the degree to which we can expect to be able to predict how vegetation is affected by external events, including future climate change. The southern fringes of the South American landmass provide a rare opportunity to examine the development of moorland vegetation with sparse tree cover in a wet, cool temperate climate of the Southern Hemisphere. We present a record of changes in vegetation over the past 17,000 years, from a lake in extreme southern Chile (Isla Santa Inés, Magallanes region, 53°38.97S; 72°25.24W; Fontana, Bennett 2012: The Holocene), where human influence on vegetation is negligible. The western archipelago of Tierra del Fuego remained treeless for most of the Lateglacial period. Nothofagus may have survived the last glacial maximum at the eastern edge of the Magellan glaciers from where it spread southwestwards and established in the region at around 10,500 cal. yr BP. Nothofagus antarctica was likely the earlier colonizing tree in the western islands, followed shortly after by Nothofagus betuloides. At 9000 cal. yr BP moorland communities expanded at the expense of Nothofagus woodland. Simultaneously, Nothofagus species shifted to dominance of the evergreen Nothofagus betuloides and the Magellanic rain forest established in the region. Rapid and drastic vegetation changes occurred at 5200 cal. yr BP, after the Mt Burney MB2 eruption, including the expansion and establishment of Pilgerodendron uviferum and the development of mixed Nothofagus-Pilgerodendron-Drimys woodland. Scattered populations of Nothofagus, as they occur today in westernmost Tierra del Fuego may be a good analogue for Nothofagus populations during the Lateglacial in eastern sites. Climate, dispersal barriers and/or fire disturbance may have played a role controlling the postglacial spread of Nothofagus. Climate change during the Lateglacial and early Holocene was a prerequisite for the expansion of Nothofagus populations and may have controlled it at many sites in Tierra del Fuego. The delayed arrival at the site, with respect to the Holocene warming, may be due to dispersal barriers and/or fire disturbance at eastern sites, reducing the size of the source populations. The retreat of Nothofagus woodland after 9000 cal. yr BP may be due to competitive interactions with bog communities. Volcanic disturbance had a positive influence on the expansion of Pilgerodendron uviferum and facilitated the development of mixed Nothofagus-Pilgerodendron-Drimys woodland.
In my project I aim at a better understanding of the evolution of malacostracan crustaceans, which includes very different groups such as mantis shrimps, krill and lobsters. Previous studies on Malacostraca, on extant as well as on fossil representatives, focussed on adult morphology.In contrast to such approaches, I will apply a Palaeo-Evo-Devo approach to shed new light on the evolution of Malacostraca. Palaeo-Evo-Devo uses data of different developmental stages of fossil malacostracan crustaceans, such as larval and juvenile stages. With this approach I aim at bridging morphological gaps between the different diverse lineages of modern malacostracans by providing new insights into the character evolution in these lineages.An extensive number of larval and juvenile malacostracans is present in the fossil record, but which have only scarcely been studied. The backbone of this project will be on malacostracans from the Solnhofen Lithographic Limestones (ca. 150 million years old), which are especially well preserved and exhibit minute details. During previous studies, I developed new documentation methods for tiny fossils from these deposits, e.g., fluorescence composite microscopy, and also discovered the first fossil mantis shrimp larvae. For malcostracan groups that do not occur in Solnhofen, I will investigate fossils from other lagerstätten, e.g., Mazon Creek and Bear Gulch (USA), or Montceaules- Mines and La-Voulte-sur-Rhône (France). The main groups in focus are mantis shrimps and certain other shrimps (e.g., mysids, caridoids), as well as the bottom-living ten-footed crustaceans (reptantians). Examples for studied structures are leg details, including the feeding apparatus, but also eyes. The results will contribute to the reconstruction of 3D computer models.The data collected in this project will be used for evaluating the relationships within Malacostraca, but mainly for providing plausible evolutionary scenarios, how the modern malacostracan diversity evolved. With the Palaeo-Evo-Devo approach, I am also able to detect shifts in developmental timing, called heterochrony, which is interpreted as one of the major driving forces of evolution. Finally, the reconstructed evolutionary patterns can be compared between the different lineages for convergencies. These comparisons might help to explain the convergent adaptation to similar ecological niches in different malacostracan groups, e.g., life in the deep sea, life on the sea bottom, evolution of metamorphosis or of predatory larvae.As the project requires the investigation of a large number of specimens in different groups, I will assign distinct sub-projects to three doctoral researchers. The results of this project will not only be published in peer-reviewed journals, but will also be presented to the non-scientific public, e.g., during fossil fairs or museum exhibitions with 3D models engraved in glass blocks.
Soil organic matter (SOM) controls large part of the processes occurring at biogeochemical interfaces in soil and may contribute to sequestration of organic chemicals. Our central hypothesis is that sequestration of organic chemicals is driven by physicochemical SOM matrix aging. The underlying processes are the formation and disruption of intermolecular bridges of water molecules (WAMB) and of multivalent cations (CAB) between individual SOM segments or between SOM and minerals in close interaction with hydration and dehydration mechanisms. Understanding the role of these mediated interactions will shed new light on the processes controlling functioning and dynamics of biogeochemical interfaces (BGI). We will assess mobility of SOM structural elements and sorbed organic chemicals via advanced solid state NMR techniques and desorption kinetics and combine these with 1H-NMR-Relaxometry and advanced methods of thermal analysis including DSC, TGADSC- MS and AFM-nanothermal analysis. Via controlled heating/cooling cycles, moistening/drying cycles and targeted modification of SOM, reconstruction of our model hypotheses by computational chemistry (collaboration Gerzabek) and participation at two larger joint experiments within the SPP, we will establish the relation between SOM sequestration potential, SOM structural characteristics, hydration-dehydration mechanisms, biological activity and biogechemical functioning. This will link processes operative on the molecular scale to phenomena on higher scales.
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Die Ionosphäre ist der ionisierte Teil der Erdatmosphäre, der sich zwischen ca. 60 und 1000 km über der Erdoberfläche erstreckt und in die Plasmasphäre übergeht. Die Photoionisation der Gase erfolgt primär durch solare EUV- und Röntgenstrahlung. Die Erdgeosphäre reagiert auf die Sonnendynamik durch mannigfaltige Veränderungen in der Magnetosphäre, Plasmasphäre, Ionosphäre und Thermosphäre, welche durch komplexe Kopplungsprozesse miteinander in Wechselwirkung stehen. Das Beobachten und Verstehen dieser Prozesse ist von großem Interesse für die Geophysik. Die Elektronendichte der Ionosphäre und Plasmasphäre beeinträchtigt die Übertragung trans-ionosphärischer Radiowellen. Die räumliche und zeitliche Rekonstruktion der Plasmadichte ist deshalb von großer praktischer Bedeutung, insbesondere für Navigations-, Fernerkundungs- und Kommunikationssysteme. Unser Projekt hat das Ziel zum besseren Verständnis der Struktur und Dynamik der Ionosphäre und Plasmasphäre sowie deren Kopplungsprozesse beizutragen. Im Einzelnen konzentrieren sich die Arbeiten auf die Entwicklung einer Methode zur Rekonstruktion des Elektronendichtegehalts der Ionosphäre und Plasmasphäre durch Assimilation von LEO Satellitendaten sowie Einbindung anderer indirekter Zusatzinformationen. Von wesentlicher Bedeutung ist hierfür die Weiterentwicklung des Plasmapausen-Position-Modells auf der Grundlage der SWARM Daten und die Einbeziehung dieses Models in den Rekonstruktionsprozess. Die erzielten Ergebnisse werden mithilfe unabhängiger Elektronendichte-Messungen und Whistler Daten validiert. Anschließend wird das Potenzial der Rekonstruktionen demonstriert und bewertet. Hierfür werden ausgewählte Weltraumwetter-Ereignisse in Kooperation mit anderen Projekt-Teams des DFG Schwerpunktprograms DynamicEarth analysiert.
The atmospheric production rate of cosmogenic radionuclides depends on the variable shielding effects of cosmic rays by the solar activity and the geomagnetic field intensity. The history of these production rate changes can be basically inferred from 14C tree ring/sediment records as well as from 10Be archived in polar ice cores. However, while both reconstruction efforts agree fairly well in view of their decadal to centennial variability, they systematically deviate, for unknown reasons, on the millennia time scale, particularly in the early Holocene and late Glacial. The project aims at pinning down the main reasons for this apparent inconsistency by combining a global carbon cycle model with an atmospheric 10Be cycle model, supported by an air/firn transfer module. This innovative attempt comprises the extension of an existing carbon cycle box model to the simulation of aerosol-borne radionuclides, backed up by novel 10Be and 7Be aerosol data as well as dedicated sensitivity studies. Thereby, the various impacts of non-production related changes on the 14C and 10Be archive data shall be investigated, focusing on possible long term changes, related to the carbon and to the atmospheric 10Be cycles. Final evaluation of the results aims at depicting realistic scenarios, which allow to reduce the reconstruction mismatch, and thus, to improve the understanding of past cosmogenic production rate changes.
Marine Organismen wie Foraminiferen, Diatomeen, Gastronomen und Korallenriffe haben entscheidende Informationen über die Ozeane in der Vergangenheit geliefert (z.B. Temperatur, Süßwassereinfluss, Zirkulation). In der Literatur gibt es allerdings keine Proxies für speziell küstennahe Milieus (z.B. Küsten-Feuchtgebiete oder Lagunen), die jedoch sehr früh von Menschen bewirtschaftet wurden. Fisch ist in der Menschheitsgeschichte das wichtigste Nahrungsmittel für Küstenbewohner gewesen, wie man an zahlreichen Funden von Fischresten in archäologischen Ausgrabungsstätten im östlichen Mittelmeerraum ablesen kann. Unter den genutzen Fischen sind Reste der Sparidae (Doraden) entlang der israelischen Küste weit verbreitet und gut erhalten. Sparidae (Doraden) sind sehr anpassungsfähig und können in hyper-salinen Lagunen als auch in Brackwasser leben. Variable d180-Werte der Sparidae Backenzähne zeigen Variationen in der Salinität früherer Küstengewässer. Im Antrag soll die Analytik auf die drei stabilen Sauerstoffisotope d170 PO4 und d180 PO von Sparidae-Überresten als Proxy für küstennahe Wassertemperaturen und Salinitäten untersucht werden. Um die drei O-Isotope voll nutzen zu können, soll die Fraktionierung zwischen d170 PO und d180 PO4 zwischen Zähnen und Wasser an heutigen Fischen untersucht werden. Die Ergebnisse werden dann auf die Ergebnisse von gut-datierten Überresten aus küstennahen Siedlungen in Israel und den angrenzenden ost-mediterranen Ländern übertragen werden. Aufgrund der großen Menge der Sparidae-Überreste wird so eine hoch-aufgelöste Rekonstruktion der Paläoumweltbedingungen möglich sein.