Das Projekt "Einfluss extremer meteorologischer Randbedingungen auf den Kohlenstoffumsatz im Boden" wird vom Umweltbundesamt gefördert und von Universität Bayreuth, Fachgruppe Geowissenschaften, Bayreuther Zentrum für Ökologie und Umweltforschung (BayCEER), Lehrstuhl für Bodenökologie durchgeführt. Extreme Witterungsbedingungen wie ausgedehnte Sommerdürren und intensive Frostphasen werden wahrscheinlich in den nächsten Jahrzehnten als Folge der globalen Erwärmung zunehmen. In einem langfristigen Feldexperiment im Fichtelgebirge, Bayern, werden derartige Extremereignisse simuliert und deren Auswirkungen auf den Kohlenstoffumsatz im Boden untersucht. Hierzu werden die Radiocarbongehalte von Boden-, Wasser- und Gasproben mit einem Beschleuniger-Massen-Spektrometer (AMS) bestimmt. Der Radiocarbongehalt der Atmosphäre wurde in den späten 50-iger und frühen 60-iger Jahren durch oberirdische Atombombentests verdoppelt und wird seit einigen Jahren zur Untersuchung des Kohlenstoffumsatzes in terrestrischen Ökosystemen genutzt. Die Kooperation mit Prof. Trumbore, University of California, Irvine, ermöglicht es eine Reduktionslinie an der Universität Bayreuth zur Herstellung von Graphit aus Boden-, Gas- und Wasserproben einzurichten, welches für die Bestimmung des Radiocarbongehaltes mit einem AMS benötigt wird.
Das Projekt "Untersuchungen zur Pleistozaenstratigraphie und Grundwasserabsenkung im Bereich der Kharga-Oasen" wird vom Umweltbundesamt gefördert und von Universität Hamburg, Archäologisches Institut, Arbeitsbereich Vor- und Frühgeschichte durchgeführt. Herausarbeiten der Phasen moeglicher Grundwasserauffuellung im Pleistozaen als Grundlage zur Kenntnis der Problematik = begrenzte Vorraete aus dem Pleistozaen oder dauernder Nachschub aus Gebieten mit rezenten Niederschlaegen (in Zusammenhang mit C14-Datierungen des Grundwassers); archaeologische Datierung der antiken Grundwasser-Nutzungs-Systeme zur Klaerung des Problems einer moeglichen Grundwasser-Absenkung bzw. eines Absinkens des artesischen Drucks.
Das Projekt "Zum Dispersionseinfluss bei Altersbestimmungen des Grundwassers im Nubischen Aquifersystem" wird vom Umweltbundesamt gefördert und von Technische Universität Berlin, Institut für Wasserbau und Wasserwirtschaft durchgeführt. Dissertation im Rahmen des Sonderforschungsbereiches 69 'Geowissenschaftliche Probleme in ariden Gebieten'. Untersuchung der Auswirkung der Dispersion auf die Altersbestimmung von Grundwasser.
Das Projekt "Radiocarbon dating of ice from a Kilimanjaro plateau glacier" wird vom Umweltbundesamt gefördert und von Paul Scherrer Institut, Labor für Radio- und Umweltchemie durchgeführt. High-alpine ice cores from mid- and low-latitude glaciers and ice caps provide regional climate signals in areas inhabited by the majority of the worlds population. Interpreting the information contained in natural climate archives requires a precise chronology. For high-alpine ice cores there is a lack of an appropriate dating tool for the lowermost section since strong ice flow induced layer thinning limits counting of annual layers in the best case to a couple of centuries and is not suitable for the oldest and deepest ice. Glacier flow is dominated by the small-scale geometry of bedrock, resulting in a strongly non-linear depth-age relationship over time, which cannot be fully resolved using physical ice flow models. Under these circumstances, radiocarbon analysis can provide an absolute date. Radiocarbon dating has been successfully applied to ice cores, when sufficient organic material such as wood fragments or insects was found. However, this has rarely been the case - a fact limiting the wider application of this technique. To overcome this problem, a recently developed approach is to use carbonaceous aerosols contained in the ice for radiocarbon dating. Carbonaceous particles are a major component of naturally occurring aerosols that are emitted ubiquitously or formed in the atmosphere and transported to potential ice core sites. Radiocarbon dating using the organic carbon fraction was applied by our group to different ice cores from Nevado Illimani (Andes, 6300 m asl), Colle Gnifetti (Alps, 4450 m asl), and Tsambagarav (Altai, 4140 m asl). For the first two ice cores the ages cover a time span from 1000 to more than 10000 years, whereas the latter has a basal ice age of approximately 6000 years. This novel radiocarbon approach is promising to help resolving the current debate about the age of the Kilimanjaro plateau glaciers. Palaeoclimate reconstructions based on six ice cores, assigned a basal age of 11700 years. Another study claims that plateau glaciers on Kilimanjaro are subject to recurring cycles of waxing and waning controlled primarily by atmospheric moisture. An absence of the ice bodies was reconstructed for the period around 850 years ago. This proposal seeks funding for a 1-year extension of the 3-years SNF project 'Radiocarbon dating of glacier ice' to finalize the PhD thesis of Alexander Zapf. The aim is the radiocarbon dating of 48 ice samples collected during our 2011 expedition to Kilimanjaro. A stratigraphic sequence of samples from the exposed vertical ice cliffs at the margins of the Northern Ice Field was obtained from horizons characterized by varying particle concentrations. The Kilimanjaro ice fields are subject to rapid areal shrinkage and thinning. (...)
Das Projekt "Land-use and management impacts on carbon sequestration in mountain ecosystems" wird vom Umweltbundesamt gefördert und von Forschungsanstalt Agroscope Reckenholz-Tänikon ART durchgeführt. Ongoing land-use and management changes in various European mountain ecosystems may alter their role as important carbon reservoirs. For soil carbon in particular meaningful data on drivers, stocks and rates is scarce and thus predictive studies on the effect of land-use and management change on carbon stored in mountain ecosystems are highly uncertain. In addition, management is a major control on standing biomass in mountain forests but as for soil carbon, the data base is poor. Reliable data are not only needed for a more substantiated assessment of land-use and management effects on ecosystem carbon storage, but also for developing management recommendations, improved mechanistic modeling and, finally, the corresponding model application in the context of greenhouse gas reporting. The project will provide carbon stocks and accumulation rates from both measurements and modeling for typical but climatically different mountain ecosystems in four European mountain ranges. The goal of the proposed research is a quantitative understanding of carbon change rates, their drivers, the implementation of results in to models currently used for national greenhouse gas inventories and, finally, the development of management recommendations for mountain ecosystems with respect to their carbon storage function. We will (i) sample soils and forest floor from well studied experimental adjacent sites differing in land-use (grasslands, forests) as well as experimental management gradients/types within grasslands and forests and make use (ii) of already existing data sets along land-use gradients. Sites span a wide range of edaphic, management, and climatic conditions in the Balkan Mountains, the Rhodope Mountains, Rila Mountains and the Alps. Auxiliary climate data for model application are available. These data will be used to derive carbon change rates for the different activities, information on the stability of sequestered carbon and to formulate management recommendations. Radiocarbon measurements of soil and roots from various sites will be used to derive carbon turnover rates. The project builds on extensive previous experience with research projects on management, land-use and related carbon sequestration in cropland, grassland, abandonment, and forest ecosystems in the Alps and in Bulgarian mountains. The main deliverables of the project will be: Knowledge rules, transfer functions and recommendations to policy makers, Comprehensive data sets that allow for scaling up from the plot to a regional landscape level and thus to settle a close link between model validation, application, and improvement. Validated mechanistic models to be used in national greenhouse gas reporting, sector land use, land use change and forestry, and Tools for implementation of both reporting issues and management recommendations in Bulgaria and Switzerland.
Das Projekt "A geoarchaeological approach to investigate human-environment interactions in the Valle Leventina" wird vom Umweltbundesamt gefördert und von Universität Zürich, Geographisches Institut durchgeführt. The focus of the project is to improve our understanding of human-environment interactions in Southern Alpine regions by detecting biogeochemical markers in soils to reconstruct the development of a landscape that was shaped by humans since millennia. Until now, information about the chronological and spatial extent of changes from a natural to a human-dominated landscape, especially in the Southern Alpine regions, has been scarce. The results of our investigation would allow us to understand where and when (pre)historic settlers installed their agricultural land. The aims are (1) to adapt, evaluate and improve the applied methods so that we can use biogeochemical markers retained in soil material (2) to quantify the anthropogenic influence and to determine the processes of human impact on the environment such as manuring and burning, and (3) to investigate the spatial extension and chronology of agricultural sites (off-site-archaeology) in the surroundings of a Bronze Age settlement in Airolo-Madrano (e.g. agricultural terraces). The processes of human impact, or the agricultural techniques used by the settlers will be documented by the analysed marker substances and radiocarbon dating.
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