Das Projekt "Permafrost Carbon Cycle Observations and Modeling across multiple spatiotemporal scales (PERCCOM)" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Biogeochemie durchgeführt. Permafrost ecosystems in the high Northern latitudes are estimated to store about 1700 Petagram of carbon, which is roughly 50% of the total global belowground carbon, or about double the amount currently contained in the global atmosphere. Future climate projections indicate a strong warming potential for these regions over the next century, which may significantly alter the biogeochemical processes governing the carbon cycle, and thus holds the potential to partly destabilize and release these enormous existing carbon reservoirs. At the same time, the database on carbon exchange fluxes between surface and atmosphere is sparse compared to the size of the region, and significant gaps exist concerning e.g. the coverage of specific landscape units, or observations during the cold season. As a consequence, many processes within the permafrost carbon cycle remain poorly understood, leading to large uncertainties in climate model simulations for this region. To close existing gaps in both flux Arctic flux databases and process understanding, integrated monitoring and modeling tools are required that provide insight into feedback mechanisms between permafrost ecosystems and climate change. This project will establish year-round observation systems in the permafrost region that integrate over multiple spatiotemporal scales to capture carbon flux variability from local to continental levels. The obtained information will be used to identify causal links between environmental drivers and patterns in carbon fluxes based on an integrated framework of atmospheric transport modeling, multivariate statistics, geostatistical inversion and biogeochemical process modeling. The resulting insights into biogeochemical mechanisms will help to improve process representation in modeling frameworks, with the overarching objective to reduce uncertainties in climate projections.
Das Projekt "Turbulent Structure Parameters over Heterogeneous Terrain - Implications for the Interpretation of Scintillometer Data" wird vom Umweltbundesamt gefördert und von Deutscher Wetterdienst, Geschäftsbereich Forschung und Entwicklung, Meteorologisches Observatorium Lindenberg, Richard-Aßmann-Observatorium durchgeführt. The turbulent exchange of heat and water vapour are essential land surface - atmosphere interaction processes in the local, regional and global energy and water cycles. Scintillometry can be considered as the only technique presently available for the quasi-operational experimental determination of area-averaged turbulent fluxes needed to validate the fluxes simulated by regional atmospheric models or derived from satellite images at a horizontal scale of a few kilometers. The scintillometer principle is based on the quantitative evaluation of intensity fluctuations of electromagnetic radiation propagating across the turbulent atmosphere over distances up to several kilometres. With the proposed project we will study some fundamental issues related to the applicability of scintillometry. Special emphasis will be put on the determination of the spatial (horizontal and vertical) and temporal variability of structure parameters (underlying the scintillometer principle) over moderately heterogeneous terrain. The project essentially relies on a coupling of field measurements (eddy-covariance techniques, scintillometry and airborne measurements) and numerical modelling using a large-eddy simulation (LES) model. With this combination the proposed project represents the worldwide first attempt both to measure the statistics of the turbulent temperature and humidity field along a scintillometer path by airborne techniques, and to simulate the pattern of the structure parameters along this path by LES thus providing an independent evaluation of the scintillometer principle.
Das Projekt "Interactions and regulation of N2 forming processes in the plant rhizosphere" wird vom Umweltbundesamt gefördert und von Universite de Neuchatel, Faculte des Sciences, Institut de Botanique, Laboratoire de Microbiologie durchgeführt. In this project we wish to investigate a so far neglected process in the terrestrial N-cycle: the anaerobic oxidation of ammonium ('anammox'), which has been shown in marine environments to contribute significantly to dinitrogen formation. We hypothesize that anoxic pockets in soil aggregates and the rhizosphere of plants represent suitable microenvironments where the anammox process may be active. With an interdisciplinary approach, combining methods from biogeochemistry and molecular microbial ecology, we aim at detecting and quantifying anammox in terrestrial environments. PCR based techniques will be applied for screening and identification of anammox bacteria in a wide range of habitats. The relative contribution of anammox and denitrification to N2 formation and the factors controlling the two processes and their interactions will be explored in microcosm experiments with 15N additions. The expected results will improve our understanding of N2 producing processes in soils and lead to a more complete picture of the terrestrial N-cycle.
Das Projekt "Ressourcensparende Entschwefelungsanlage auf der Basis eines Kreisprozesses mit verfahrenstechnischen Maschinen" wird vom Umweltbundesamt gefördert und von Technische Universität Clausthal, Institut für Energieverfahrenstechnik und Brennstofftechnik durchgeführt. Die bei der Verbrennung von Braunkohle entstehenden Abgase enthalten je nach der eingesetzten Kohle unterschiedlich hohe Schadstoffbelastungen. Zur Einhaltung der TA-Luft bzw. der in der Verordnung ueber Grossfeuerungsanlagen vorgeschriebenen Emissionsgrenzwerte ist eine Entschwefelung der Abgase notwendig. Bisher eingesetzte trockene Entschwefelungsverfahren weisen einen hohen, d. h. ueberstoechiometrischen Verbrauch an Zusatzstoffen fuer die Entschwefelung auf. Im Projekt B11 wird eine ressourcensparende Entschwefelung entwickelt. Der Vorgang der Entschwefelung basiert auf einer Chemisorption von Schwefeldioxid mit Calciumverbindungen. Der Verbrauch von Calciumverbindungen fuer die Chemisorption wird durch Vermindern der Entschwefelungstemperatur, Entschwefeln bei hoher Feuchte, Kreisprozessfuehrung und teilweiser Aufbereitung / Konditionierung des Additivs vermindert. Hierzu wird eine neuartige verfahrenstechnische Maschine entwickelt und getestet.