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Found 34 results.

Soil-gas transport-processes as key factors for methane oxidation in soils

Das Projekt "Soil-gas transport-processes as key factors for methane oxidation in soils" wird vom Umweltbundesamt gefördert und von Albert-Ludwigs-Universität Freiburg, Institut für Geo- und Umweltnaturwissenschaften, Professur für Bodenökologie durchgeführt. Methane (CH4) is a major greenhouse gas of which the atmospheric concentration has more than doubled since pre-industrial times. Soils can act as both, source and sink for atmospheric CH4, while upland forest soils generally act as CH4 consumers. Oxidation rates depend on factors influenced by the climate like soil temperature and soil moisture but also on soil properties like soil structure, texture and chemical properties. Many of these parameters directly influence soil aeration. CH4 oxidation in soils seems to be controlled by the supply with atmospheric CH4, and thus soil aeration is a key factor. We aim to investigate the importance of soil-gas transport-processes for CH4 oxidation in forest soils from the variability the intra-site level, down to small-scale (0.1 m), using new approaches of field measurements. Further we will investigate the temporal evolution of soil CH4 consumption and the influence of environmental factors during the season. Based on previous results, we hypothesize that turbulence-driven pressure-pumping modifies the transport of CH4 into the soil, and thus, also CH4 consumption. To improve the understanding of horizontal patterns of CH4 oxidation we want to integrate the vertical dimension on the different scales using an enhanced gradient flux method. To overcome the constraints of the classical gradient method we will apply gas-diffusivity measurements in-situ using tracer gases and Finite-Element-Modeling. Similar to the geophysical technique of Electrical Resistivity Tomography we want to develop a Gas Diffusivity Tomography. This will allow to derive the three-dimensional distribution of soil gas diffusivity and methane oxidation.

Simulated field environment with combined salt and drought stresses as a platform for phenotyping plant tolerance to salinity

Das Projekt "Simulated field environment with combined salt and drought stresses as a platform for phenotyping plant tolerance to salinity" wird vom Umweltbundesamt gefördert und von Technische Universität München, Lehrstuhl für Pflanzenernährung durchgeführt. Salinity occurs often simultaneously with drought stress. Therefore, breeding for tolerance to combined both stresses can contribute significantly to crop yield. However, classical selection in salinity has generally been unsuccessful, partly due to high variability of salt stress resulting from the different salinity and drought status. Unfortunately, the use of unrealistic stress protocols for mimicking salinity and drought stress is the norm rather than the exception in biotechnological studies. Therefore, the great challenge is to gain knowledge required to develop plants with enhanced tolerance to field conditions. Our overall hypothesis is that a realistic stress protocol simulating a field environment with combined salt and drought stress as a platform for precision phenotyping of plant tolerance to salinity may solve this problem. This study will demonstrate that highly managed stress environments can be created and key traits of plants can be characterised by using advanced non-destructive sensors that are able to identify relevant traits of plants.

Biological soil crust algae in the polar regions - biodiversity, genetic diversity and ecosystem resilience under global change scenarios

Das Projekt "Biological soil crust algae in the polar regions - biodiversity, genetic diversity and ecosystem resilience under global change scenarios" wird vom Umweltbundesamt gefördert und von Universität Köln, Biozentrum, Botanisches Institut durchgeführt. Terrestrial green algae and cyanobacteria are typical and abundant components of biological soil crusts in the Polar Regions. These communities form water-stable aggregates that have important ecological roles in primary production, nitrogen fixation, nutrient cycling, water retention and stabilization of soils. Although available data on green algae and cyanobacteria are generally very limited for the Arctic and Antarctica, their functional importance as ecosystem developers in nutrient poor environments is regarded as high. Therefore, the main goal of the interdisciplinary project is, for the first time, a precise evaluation of their 1.) Biodiversity as well as of 2.) The infra-specific genetic diversity, 3.) ecophysiological performance and 4.) transcriptomics of the most abundant taxa in biological soil crusts isolated from the Antarctic Peninsula and Arctic Svalbard. Biodiversity will be investigated using a classical culture approach in combination with molecular-taxonomical methods as well as with metagenomics. The infra-specific genetic diversity of the most abundant green algae and cyanobacteria will be studied using fingerprinting techniques, and a range of selected populations characterized in relation to their physiological plasticity. Temperature and water availability, two key environmental factors for terrestrial organisms, are currently changing in Polar Regions due to global warming, and hence their effect on growth and photosynthesis response patterns will be comparatively investigated. The data will indicate whether and how global change influence population structure and ecological performance of key organisms in polar soil crusts, and help to make predictions on the future significance of the ecological functions of these pioneer communities. Such a multiphasic approach has never been applied before to soil algae and cyanobacteria in both Polar Regions, and hence represents one of the key innovations of this proposal.

Multiple-site seismic hazard assessment

Das Projekt "Multiple-site seismic hazard assessment" wird vom Umweltbundesamt gefördert und von Karlsruher Institut für Technologie (KIT), Geophysikalisches Institut durchgeführt. The classical point wise Cornell-McGuire probabilistic seismic hazard assessment (PSHA), which is widely used for seismic hazard mapping and development of design codes, does not allow direct estimation of multiple-location hazard for distributed structures and facilities: what is the (annual) probability that specific level of ground motion will be exceeded simultaneously in several sites? It is possible to extent the classical methodology to the multiple sites problem considering also ground-motion correlation. We study multiple-location PSHA, as compared with the classical point wise PSHA, using Monte Carlo simulation. Specific items are:(1) Development of the algorithms for multiple-location PSHA;(2) Analysis of the role of the geometry of multiple sites, correlation of ground motion, and evel of seimicity for multiple-location PSHA;(3) Study of correspondence and differences between multiple-location PSHA and classical point wise PSHA and analysis of possibility of utilization of classical PSHA procedures for simplified multiple-location hazard assessment.The project is innovative because only few attempts have been made so far regarding our research questions.

Population biology and genetics of dark septate endophytes (DSE)

Das Projekt "Population biology and genetics of dark septate endophytes (DSE)" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Professur für Forstschutz und Dendrologie durchgeführt. We study population biology and life histories of DSE. Dark septate root endophytes (DSE) are ubiquitous fungal tree root colonizers in temperate and boreal conifer forest ecosystems. The supposedly asexual Phialocephala fortinii was identified as the main component of these DSE but constitutes a species complex in its own right. Species in this complex are morphologically indistinguishable with one exceptition; Acephala applanata was described as a new species which is characterized by the absence of aerial mycelium and slow growth rate. Application of biological, phylogenetic and population genetic species concepts will allow to discriminate additional species. The experimental programme is multi-disciplinary in approach, utilizing classical mycological and molecular genetic techniques.

Native plants and mycorrhizal fungi in wind erosion control in the Kailash-Manasarovar region (Tibet, China)

Das Projekt "Native plants and mycorrhizal fungi in wind erosion control in the Kailash-Manasarovar region (Tibet, China)" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Professur für Forstschutz und Dendrologie durchgeführt. We study the effects of plants and root-associated fungi on wind erosion within the alpine environment of Tibet. China is one of the countries most affected by desertification processes and Tibet, in particular, a key region in desertification combat. The presented project focuses on the Barkha Plain surrounded by Mount Kailash and the Lake of Manasarovar (Ngari Prefecture). This Western Tibet region experienced little scientific attention but, nowadays, faces rapidly increasing touristic activities and expanding local settlements associated with socio-economic changes that are serious threats to the delicate ecological balance and potential triggers of desertification. It exists almost unanimous agreement that revegetation is the most efficient and promising strategy to combat wind erosion and desertification in the long term. However, re-colonising success is often poor, mainly under extreme environmental conditions. Compared to conventional practices, the approach of the presented project attains better accordance with natural succession processes and promises acceleration of both plant and soil development and, conclusively, more efficient desertification control. The project assesses the potential of native plants and symbiotic fungi to control wind erosion and desertification processes. It aims to identify key plants and fungi that increase soil aggregate stability and efficiently drive succession into a natural and self-maintaining cycle of the ecosystem. Furthermore, it provides crucial information for implementing environmentally compatible and cost-effective measures to protect high-elevation ecosystems against desertification. Within three successional stages (early, intermediate, late), field investigations are performed on the basis of Modified-Whittaker plots. Classic methods of vegetation analysis and myco-sociology are combined with analysis of distribution patterns at different scales (patchiness, connectivity). Comprehensive soil analysis is performed comprising grain size distribution, aggregate stability, pH as well as water and nutrient contents. Additionally, important parameters of wind erosion are measured concurrently and continuously to assess their magnitude and variability with respect to vegetation and soil at different levels of development. The parameters addressed, include sediment transport, air temperature, radiation, precipitation, relative humidity as well as speed and direction of wind. Surface moisture is recorded periodically and roughness described. Species and environmental parameters are checked for spatial correlation. Cutting edge technologies are applied in laboratory work, comprising molecular methods for fungal species identification and micro-tomography to analyse soil structure. Furthermore, successfully cultivated fungi and plants are subject of synthesis experiments and industrial propagation in view of practical implementation in restoration measures.

Surface Semi-Geostrophic Dynamik: Vermischung von lokal nach nonlokal Dynamik

Das Projekt "Surface Semi-Geostrophic Dynamik: Vermischung von lokal nach nonlokal Dynamik" wird vom Umweltbundesamt gefördert und von Universität Hamburg, Fachbereich Erdsystemwissenschaften, Institut für Meereskunde durchgeführt. Empirische und numerische Studien zeigen, dass sich ein signifikanter Anteil der Dynamik im Ozean auf Skalen kleiner als der Mesoskala abspielt. Für die korrekte Parameterisierung der Vermischung in Klimamodellen ist es wichtig, die Eigenschaften dieser Dynamik und ihrer Rolle beim turbulenten Energietransfer, sowie bei der Vermischung von Wärme, Nährstoffen und Schadstoffen zu verstehen. In diesem Projekt streben wir an, die semi-geostrophischen Approximation zu benutzen, um die laterale Vermischung im Ozean aufgrund submesoskaliger Dynamik insbesonder durch an Rändern ereugten ageostrophischen Wirbeln zu untersuchen. In dieser Studie sollen numerische Experimente zur surface semi-geostrophic Turbulenz durchgeführt werden, um den advektiven und diffusiven Effekt der Wirbel auf passive Tracer zu analysieren. Verschiedene Experimente mit unterschiedlichen Rossby-Zahlen sollen durgchgeführt werden, um die Auswirkungen der Frontendynamik auf die Verteilung der Tracer zu untersuchen. Schließlich sollen die Ergebnisse mit anderen klassischen Turbulenzmodellen wie der surface quasi-geostrophic approximation verglichen werden.

Eine neuartige Methode zur bodengebundenen Fernerkundung von Profilen der Wolkenmikrophysik

Das Projekt "Eine neuartige Methode zur bodengebundenen Fernerkundung von Profilen der Wolkenmikrophysik" wird vom Umweltbundesamt gefördert und von Ludwig-Maximilians-Universität München, Meteorologisches Institut durchgeführt. Ziel des Projekts ist die Entwicklung einer neuen bodengebundenen kombinierten passiven und aktiven Fernerkundungsmethode zur Ableitung von Vertikalprofilen der Mikrophysik von konvektiven Wolken. Diese Art von Wolken spielt eine entscheidende Rolle im Klima, da sie sowohl einen großen Einfluss auf die Strahlungsbilanz als auch auf den globalen Wasserhaushalt haben. Die Lebensdauer und Albedo von konvektiven Wolken werden durch die Wechselwirkung zwischen dem Wachstum der Wolkentröpfchen in vertikaler Richtung und der Aufnahme von Aerosol beeinflusst. Da die meisten Fernerkundungsmethoden nur die Oberseite von Wolken beobachten, kann die bodengebundene Fernerkundung von Wolkenseiten einen wesentlichen Beitrag zur Untersuchung des Wolkentröpfchenwachstums leisten. Klassische Methoden versagen bei komplexen Wolkengeometrien und hoher räumlicher Auflösung, da sie auf 1D Rechnungen des Strahlungstransfers basieren, die auf Beobachtungen von der Seite aus nicht anwendbar sind. In unserem Projekt untersuchen wir daher die Auswirkungen von komplexen Wolkengeometrien auf die Fernerkundung des Wolkentröpfchenprofils mit Hilfe von 3D Strahlungstransportrechnungen. Ein wesentlicher Bestandteil dieses Projekts ist zudem die Integration eines passiven Spektrometers und eines aktiven Wolkenradars in eine gemeinsame Mess-Plattform, um diese Rechnungen zu validieren und schon entwickelte Methoden zu testen. Gestützt auf die Messungen dieser zwei Instrumente entwickeln wir aktuell ein Retrieval der Wolkenmikrophysik, das die Geometrie der Wolken mit einbezieht. In dem vorliegenden Text geben wir einen Zwischenbericht über die erste Förderungsphase und beantragen die Fortsetzung der Förderung um ein drittes Jahr, die dem Doktoranden ermöglichen soll, das Projekt und seine Doktorarbeit zu vollenden. In diesem zusätzlichen Jahr sollen die für das passive Spektrometer und das aktive Wolkenradar bereits erarbeiteten Methoden und Erkenntnisse in einem gemeinsamen Retrieval der Wolkenmikrophysik zusammengeführt werden. Dieses Retrieval soll in einem weiteren Schritt an Hand von in-situ Daten validiert und getestet werden, die im Rahmen der HD(CP)2 Messkampagne gemessen wurden.

Process study of vertical mixing near the sea floor inside the central valley of the Mid-Atlantic Ridge near 37°N

Das Projekt "Process study of vertical mixing near the sea floor inside the central valley of the Mid-Atlantic Ridge near 37°N" wird vom Umweltbundesamt gefördert und von Alfred-Wegener-Institut für Polar- und Meeresforschung, Fachbereich Klimawissenschaften, Sektion Physikalische Ozeanographie der Polarmeere durchgeführt. Vertical mixing associated with dissipation of turbulent kinetic energy sustains the circulation of the deep and abyssal ocean. New evidence is emerging that the highest mixing rates are found within the central valleys and ridge flank (transform) canyons of mid-oceanic ridge systems. An expedition is proposed to take place in August 2010 during which near-bottom oceanographic and marine-geologic measurements will be carried out in the central valley of the Mid-Atlantic Ridge near 37°N, using an autonomous underwater vehicle (AUV), complemented by 'classical' lowered and mooring-based techniques. It is currently unclear, which physical mechanisms control the intense turbulent dissipation in deep ocean canyons. Recent studies point to a potential role of hydraulic jumps, which have been observed in shallow water studies. We aim at testing whether tidally varying hydraulic jumps can explain the observed large vertical mixing over a sill in the central valley. To resolve the jumps AUV-based high-resolution horizontal fields of near-bottom turbulent kinetic energy dissipation and of flow velocities will be obtained. Further, high-resolution AUV multi-beam echo sounder mapping will allow us to study (i) the relationship between vertical mixing processes and the bathymetry, and (ii) the dynamic processes underlying the 'mixing active' morphology.

Formation of brine channels in sea ice

Das Projekt "Formation of brine channels in sea ice" wird vom Umweltbundesamt gefördert und von Fachhochschule Münster, Fachbereich Physikalische Technik durchgeführt. Within this interdisciplinary project the formation of brine channels in sea ice will be explored. The microscopic properties of sea ice, especially the permeability plays an important role for the energy exchange between ocean and atmosphere and is determined by the brine channel volume. The brine channel structure will be measured by computer tomography and image analysis. We intend to describe the channel structure by two phenomenological models, a morphogenesis approach of Alan Turing in connection with the phase transition theory of Ginzburg and Landau, and the phase field method with respect to the Cahn-Hilliard equation. We solve these nonlinear evolution equations in two and three dimensions and compare the size and texture of the brine channels with the measurements. In addition to the phenomenological equations we support our studies with molecular dynamics simulations and the density functional theory in order to obtain deeper insights at the molecular scale. Comparative first-principles studies will then enhance the trust in the extracted parameters and will lead to classical density functional for the two phases. We will discuss the phase transitions in terms of a phenomenological theory based on microscopic parameters and try to extract the underlying mechanism for the formation of water-ice boundaries. Specifically, we want to explore three theoretical questions: (i) How are ice-water melting fronts moving, (ii) How are brine channels formed and (iii) How do surface properties influence the structure formation of brine channels. The project is based on the experiences of three fields, the theoretical biological physics, chemical physics and the many-body theory. The final aim of the project is to provide input parameters for global climate models.

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