Das Projekt "Schwerpunktprogramm (SPP) 1315: Biogeochemische Grenzflächen in Böden; Biogeochemical Interfaces in Soil, Highly-resolved imaging in artificial and natural soils to yield dynamics and structure of interfaces from oxygen, pH and water content" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Universität Potsdam, Institut für Erd- und Umweltwissenschaften.In soils and sediments there is a strong coupling between local biogeochemical processes and the distribution of water, electron acceptors, acids, nutrients and pollutants. Both sides are closely related and affect each other from small scale to larger scale. Soil structures such as aggregates, roots, layers, macropores and wettability differences occurring in natural soils enhance the patchiness of these distributions. At the same time the spatial distribution and temporal dynamics of these important parameters is difficult to access. By applying non-destructive measurements it is possible to overcome these limitations. Our non-invasive fluorescence imaging technique can directly quantity distribution and changes of oxygen and pH. Similarly, the water content distribution can be visualized in situ also by optical imaging, but more precisely by neutron radiography. By applying a combined approach we will clarify the formation and architecture of interfaces induces by oxygen consumption, pH changes and water distribution. We will map and model the effects of microbial and plant root respiration for restricted oxygen supply due to locally high water saturation, in natural as well as artificial soils. Further aspects will be biologically induced pH changes, influence on fate of chemicals, and oxygen delivery from trapped gas phase.
Das Projekt "Speläotheme aus der Sibirischen Arktis: Einzigartige Archive vergangener Temperatur- und Feuchtebedingungen während des späten Miozäns." wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Universität Bochum, Institut für Geologie, Mineralogie und Geophysik, Lehrstuhl für Sediment- und Isotopengeologie.Der Beginn der nordhemisphärischen Vereisung und die Entwicklung kontinuierlichen Permafrostes in Eurasien zwischen dem Ende des Miozäns und dem frühen Pleistozän zählt zu den bedeutendsten klimatischen Ereignissen des Känozoikums. Der Zeitpunkt extensiver Vereisung auf den Kontinenten und des Arktischen Ozeans und damit verbundene Veränderungen der klimatischen Bedingungen bleibt bislang ungenau bestimmt.Speläotheme (sekundäre Höhlenkarbonate) stellen ein wichtiges Archiv kontinentaler Umweltbedingungen dar, welches durch besonders genaue radiometrische Altersmodelle für eine grosse Bandbreite an Paläoklimaproxies charakterisiert ist.Wir konnten erfolgreich diagenetisch unveränderte und datierbare Proben aus Zentral- und Nordsibirien identifizieren und schlagen eine Multi-proxy-Studie an U/Pb-datierten Stalagmiten vor. Diese Studie wird Einblicke in die thermalen und hydrologischen Bedingungen zwischen 10.3 Ma und 8 Ma liefern. Wasser aus in den Speläothemen eingeschlossenen Fluidinklusionen wird auf seine Isotopenzusammensetzung hin untersucht. Zudem wird die in den Speläothemen beobachtete Lamination genutzt, um die Saisonalität während des Torton und Messiniums zu rekonstruieren. Wir suchen finanzielle Unterstützung für die parallele Analyse der Isotopie des Fluidinklusionswassers, der Sauerstoff- und Kohlenstoffisotopie des Karbonates, und der Elementkonzentration in den Speläothemen. Diese Kombination geochemischer Methoden wird Einblicke in regionale Umweltbedingungen, die Niederschlagshistorie und Temperaturen während des Miozäns und vor der Entwicklung kontinuierlichen Permafrostes geben. Zusätzliche Proben werden genutzt, um den Wechsel vom eisfreien zu einem durch Permafrost charakterisierten Sibirien zeitlich genauer einzugrenzen.Das vorgeschlagene Projekt wird unser Wissen zur atmosphärischen Zirkulation, und daran geknüpfter Veränderungen des Feuchte- und Temperaturregimes während eines saisonal eisfreien Arktischen Ozeans erweitern.
Das Projekt "Schwerpunktprogramm (SPP) 1315: Biogeochemische Grenzflächen in Böden; Biogeochemical Interfaces in Soil, Quantification of active interfaces with respect to dissolved chemicals in unsaturated structured soil" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Helmholtz-Zentrum für Umweltforschung GmbH - UFZ, Department Bodenphysik.During the first project period we developed a general approach to quantify soil pore structure based on X-ray micro-tomography Vogel et al. (2010) which is applicable at various scales to cover soil pores larger that 0.05 mm in a representative way. Based on this method we generated equivalent network models to numerically simulate flow and transport of dissolved chemicals. The existing network model was extended to handle reactive transport and infiltration processes which are especially critical for matter flux in soil. The results were compared to experimental findings. The original research question 'what does a particle see on its way through soil' could be answered quantitatively for various boundary conditions including steady state flux and infiltration. However, we identified various critical aspects of the proposed modeling concept which will be in the focus of the second period. This includes 1) the spatial arrangement of interfaces having different quality which is crucial for chemical interactions and pore scale water dynamics, 2) the realistic multiphase dynamics at the pore scale which need to reflect the dynamic pressure and movement of trapped non-wetting phase and 3) the parametrization of structural complexity which need to be developed beyond the measurement of continuous Minkowski functions to allow the development of quantitative relations between structure and function. These aspects will be explored in a joint experiments in cooperation with partners within the SPP.
Das Projekt "The global biogeochemical cycle of selenium: sources, fluxes and the influence of climate" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Eidgenössische Technische Hochschule Zürich, Institut für Integrative Biologie.Selenium is a natural trace element that is of fundamental importance to human health. However, it is also an element with a small range between dietary deficiency (less than 40 micrograms per day) and toxic dosages (over 400 micrograms per day). The extreme geographical variation in environmental selenium concentrations has resulted in significant health problems. For example, in China, widespread serious diseases such as Kashin-Beck and Keshan disease have been related to the very low selenium contents of locally produced food. To deal with health problems related to deficient or excess levels of selenium in the environment, it is essential to get a better understanding of the processes that control the global distribution of selenium. This research project is aimed at investigating potentially important sources, pathways and sinks of natural selenium species. Two interdisciplinary work programs are planned that combine different scientific methodologies in the field of environmental biogeochemistry. One work program will focus on the production of volatile selenium species by marine phytoplankton, which could be an important source of selenium to the continent. Research methods involve microcosm studies with marine phytoplankton and subsequent trapping and characterization of produced volatile selenium species. Expected results will greatly contribute to an improved understanding of the role of marine phytoplankton in the global selenium cycle. Also, field experiments are planned to quantify fluxes of volatile selenium compounds from continental environments. The deposition of atmospherically transported selenium on the continent will be the main focus of the other work program. A key field site for this work program is the Chinese Loess Plateau, which has the potential to serve as environmental archive of atmospherically deposited selenium over the last 2.6 million years. The presence and mobility of trace elements will be studied in the loess sediments using different geochemical analytical techniques. Expected results will advance understanding of atmospheric selenium deposition and give insight in the role that climate plays on the continental abundance of selenium. These studies will pave the way for future predictions of selenium distribution patterns based on climate data. Knowledge on biogenic selenium production in the ocean and continental deposition of selenium is needed to understand the environmental fate of both natural and anthropogenic selenium emissions. This understanding is essential to prevent future selenium health hazards in a world that is increasingly affected by human activities.
Das Projekt "Forschergruppe (FOR) 1246: Kilimanjaro ecosystems under global change: Linking biodiversity, biotic interactions and biogeochemical ecosystem processes, Impact of climate and land use on the diversity and functioning of pollinators, decomposers and herbivores (KiLi SP 7)" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Julius-Maximilians-Universität Würzburg, Theodor-Boveri-Institut für Biowissenschaften, Biozentrum, Lehrstuhl für Zoologie III (Tierökologie und Tropenbiologie).SP7 analyses two important ecosystem processes: pollination and decomposition. Species richness and abundance of pollinators sampled with coloured UV-reflecting pan traps will be related to floral diversity (SP4, SP5), vegetation type, altitude and climate (SP1 to SP3). Plant-pollinator interaction webs will be quantified to estimate specialization and connectance in relation to climatic variables (SP1), land use and biodiversity (SP4, SP5, SP8). Fruit and seed set of five abundant flowering plant species will be measured for open, hand-pollinated and exclosure treatments to evaluate pollinator limitation in relation to climate, land use and biodiversity. Transplant and pollination experiments with an endemic and a wide-spread Impatiens species will be performed to analyse the importance of pollinator-mediated gene flow (SP4). From combined litter and soil samples the meso- and macrofauna will be extracted. Furthermore the epigaeic fauna is sampled using pitfall traps. Identification to morphospecies, measuring of body size and DNA-barcoding will be applied to estimate biodiversity and size structure (SP 8). Diversity, abundance and size structure of soil fauna taxa will be related to floral diversity, climate, land use, biogeochemical processes (SP1-3) and aboveground diversity (SP4-8). Decomposition rates and the contribution of size classes of decomposers will be measured using litter bags differing in mesh size. Experiments with litter mixtures will be performed to test for adaptations of decomposers to local conditions as well as the effect of litter diversity on decomposition rates along altitudinal gradients.
Das Projekt "Interface texturing for light trapping in solar cells" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Ecole Polytechnique Federale de Lausanne, Institut Interdepartemental de Microscopie Electronique.The project investigates light absorption in thin film silicon solar cells, one of the leading technologies for the generation of low cost of renewable energy. Because silicon is a rather weak absorber, light scattering at interface textures is used to enhance the absorption. Understanding of light scattering and the corresponding absorption enhancement in the device represents a scientific challenge that spans optics, device physics and material science. Among the textures used so far, solar cell technology makes use almost exclusively of random structures that develop during the growth of on of the of supporting films or the substrate. The idea of the project is, to understand the details of the scattering event, and ideally to propose more appropriate surface structures than the existing ones. Therefore, it is intended to develop new processes for controlled surface modifications, and to develop new modelling tools for numeric analysis and understanding.
Das Projekt "Forschergruppe (FOR) 816: Biodiversity and Sustainable Management of a Megadiverse Mountain Ecosystem in South Ecuador, Forschergruppe FOR 816/2: Biodiversität und nachhaltiges Management eines megadiversen Hochgebirgsökosystems in Südecuador - D1: Analyse und Synthese von paläoökologischen Datensätzen zur Offenlegung von Mustern der Vegetation und Biodiversität in neotropischen Gebirgen und ihre Reaktionen auf Klima-, Feuer-, und Landnutzungsänderungen durch Zeit und Raum" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Universität Göttingen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Abteilung für Palynologie und Klimadynamik.Die südecuadorianischen Anden beherbergen eine außergewöhnlich hohe Artenvielfalt. Viele verschiedene Umweltfaktoren beeinflussen sich auf sehr limitiertem Raum und erschaffen so einzigartige und komplexe Ökosysteme. Dieses Gebiet ist jedoch auf Grund des zunehmenden menschlichen Einflusses durch die fortschreitende Intensivierung der Landnutzung und des globalen Wandels hochgefährdet. Wir wissen nur wenig über die paläoökologische Geschichte und Landschaftsdynamik dieses Gebiets. Die Information über das warum und wie einer Veränderung von Ökosystemen ist unerlässlich für die Entwicklung innovativer Strategien für Naturschutz und im Hinblick auf zukünftige Klimaveränderungen. In der vorliegenden Studie werden palynologische Analysen aus den südecuadorianischen Anden vorgestellt, die dazu beitragen, Muster und Prozesse heutiger und vergangener Ökosysteme zu beleuchten. Eine paläoökologische Studie des Quimsacocha-Vulkanbeckens auf der östlichen Erhebung der Westkordillere der südecuadorianischen Anden deckt Klima-, Vegetations- und Brandregimeveränderungen in dieser Region seit dem frühen Holozän auf. Das mittlere Holozän war eine Zeit starker Umweltveränderungen, verursacht durch ein trockenes und wohl wärmeres Klima. Während des späten Holozäns wechselten sich mehrere Kalt-und Warmphasen ab. Brände können seit dem frühen Holozän im Gebiet verzeichnet werden. Sie könnten ein erstes Zeichen menschlichen Einflusses darstellen. Mit anderen paläoökologischen Aufzeichnungen aus den südecuadorianischen Anden verglichene multivariate Analysen decken teilweise konstrastierende Entwicklungen an den verschieden Standorten auf, die vermutlich durch die Heterogenität der Umweltfaktoren zu erklären sind. Weiterhin wurden Studien zum Verhältnis von heutigem Pollenregen mit der Vegetation in der Podocarpus Nationalpark-Region durchgeführt, um die Pollenverbreitungsmuster innerhalb der verschiedenen Vegetationstypen, prämontaner Wald, unterer Bergwald, oberer Bergwald und Páramo, zu verstehen und damit eine bessere Grundlage zur Interpretation fossiler Pollendaten zu schaffen. Ein Vergleich von Abundanz und An-/Abwesenheitsdaten von Familien als taxonomischer Einheit für Pollen- und Vegetation zeigt, dass Diversität, Verbreitung und Häufigkeiten beider Datensätze gut miteinander in Verbindung gebracht werden können. Dennoch werden die Muster durch variierende Anteile von durch Ferntransport eingetragenen Pollenkörnern sowie durch unterschiedliche Pollenproduktivität verschiedener Taxa und heterogene Windsysteme beeinflusst. Analysen der Pollenakkumulationsraten, die über drei Jahre erfasst wurden, lassen auf eine geringe inter-annuelle aber hohe räumliche Variation in den Daten schließen. (Text gekürzt)
Das Projekt "Wind Tunnel study of sheltering effect by vegetation in the atmospheric boundary layer: implication for soil erosion and snow transport" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft, Eidgenössisches Institut für Schnee- und Lawinenforschung.Soil erosion and desertification, blowing and drifting snow, transport of pollen and seeds, dust entrainment and transport of (particulate) pollutants are some among a large number of processes governed by wind blowing on an erodible surface. The impact of these processes on the environment and both directly and indirectly on the human societies is huge, having implications for land surface geomorphology, human health, water resources, soil fertility and ecosystem biogeochemistry. In order to have full understanding of the physical mechanisms responsible for soil/snow entrainment, it is thus of crucial importance to investigate the very inner layer of the atmosphere, as close as possible to the ground. The interaction between the wind and the earth surface gives rise to a turbulent boundary layer which can lead to erosion of particles, often ranging from micron sized dust to millimeter sand grains. The action of the turbulent boundary layer essentially lead to a stress acting on the surface and ultimately a force acting on each single particle. In fluid mechanics the latter is referred to as the shear stress. In all surface transport models (from dust in deserts, to gravel in rivers, to PM10 particles in an industrial area) the shear stress is the key parameter. The amount of particles transported has almost always been described as a function of the difference between the shear stress and a threshold. Therefore, the prediction of the shear stress acting on the surface is a crucial pre-requisite to estimate mass transport rates. Very often, erodible soil or snow surfaces are covered by vegetation. It has long been known that vegetated surfaces prevent soil erosion by means of mainly three mechanisms. Firstly vegetation shelters the soil by simply reducing the surface exposed to the wind. Secondly, vegetation can trap particles in motion hence acting like a sink for sediments. Finally, vegetation decreases the shear stress acting on the erodible ground by absorbing the momentum flux from the airflow above, therefore weakening the erosive power of the wind. In this project we are concerned with quantifying this last effect for a selected variety of plants species and plant cover densities. The long term application of such study will be to develop a model which, for a given wind velocity and vegetation cover is able to predict the shear stress acting on the bottom surface. Such information can then be used as an input for sediment/snow transport models.
Das Projekt "Bioactive natural products - linking chemical and biological information for lead discovery, preliminary SAR and assessment of undesired pharmacological properties" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Universität Basel, Department Pharmazeutische Biologie.Small molecule natural products are a prolific source of inspiration for the development of new drugs, and essential tools in basic biomedical research as probes of biological functions. The contribution of academic laboratories in natural products discovery has been essential. The limiting factor of traditional approaches in bioactivity-directed natural product research has been the tedious process of purification and identification of active molecules from a highly complex extract matrix. Recent technological advances enable substantial improvements in efficiency via a consequential miniaturization of the screening and discovery process, and automation of certain process steps. The aim of the project is to discover small molecule natural products leads from plants and fungi acting against clinically relevant and/or emerging targets in important disease areas. The targets have been selected on the basis of specific criteria, such as (i) novelty and importance of target; (ii) lack of specific/selective inhibitors; (iii) need for enhancement of structural diversity of ligands; (iv) difficulty/impossibility to use rational drug discovery approaches; (v) access to animal models. Indications include CNS (selective GABA-A receptor agonists), inflammation and cancer (modulation of angiogenesis and lymphangiogenesis, inhibition of PI3 kinases). In addition, a screening for hERG channel inhibition will be carried out as the currently most critical anti-target in drug discovery & development. An extract library and a technology platform for the miniaturized discovery of natural products will be used. The library consists of currently 1000 plant and fungal extracts. An ethnomedicine-based focussed sub-library will be specifically tested for GABAA receptor agonistic properties. All process steps in the screening and consecutive lead identification are miniaturized, in part automated, and based on the 96-well microtiter footprint. Most of the assays are via external collaborations, and some assays involving cell signalling are established in-house. Prioritized extracts are submitted to HPLC-based activity profiling with microtiter-based fractionation of column effluent, and simultaneous on-line spectroscopic (PDA, ion-trap ESI and APCI-MS, and ESI-TOF) analysis. Compound dereplication and identification is supported by off-line microprobe NMR spectroscopy. Around the active target molecules, structurally related compounds will be characterized to generate small 'virtual' libraries for preliminary structure activity relationships. Calculation of physico-chemical data and secondary bioassays will characterize leads, and shortlisted compounds will be tested in vivo for proof of concept. For this purpose, compounds of interest are isolated in a targeted manner in amounts of up to several hundred mg.
Das Projekt "Natural and anthropogenic aerosols from ice and sediment Alpine records: Climatic, stratigraphic, and environmental implications." wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: Universite de Geneve, Institut F.-A. Forel.This follow-up project aims to reconstruct natural (climatic) and anthropogenic-induced hydrological changes and to provide new insights on the anthropogenic pollutants emitted in European environment over the last centuries, by focusing on: (1) The largest freshwater lake of Western Europe (Lake Geneva) and especially on industrial (trace metals) and microbial (pathogenic bacterial activity and resistance to antibiotic) pollution in the Vidy Bay; where are discharges the treated wastewaters of Lausanne since 50 years. (2) A drinking reservoir (Lake Brêt) in order to evaluate the impacts of agricultural activities and sewage emissions on the pollution of drinking water in Switzerland over the last century. Results demonstrate a slight enrichment in anthropogenic heavy metal since the 1950s but an additional (agricultural) source of copper during the last decade. In the absence of industries in the catchment, the records of DDT and PCBs highlight the long-range atmospheric transport of POPs that contaminated rural water resources via catchment runoff. (3) Human impact on the deposition of anthropogenic and natural trace element fluxes were measured in sediment cores from Lake Biel and from two upstream lakes (Lake Brienz and Lake Thun), all three connected by the Aare River. Results indicate that that the construction of sediment-trapping reservoirs significantly decreased regional riverine sediment discharge. Radiometric dating of the sediment core from Lake Biel furthermore identified hydrological releases of anthropogenic radionuclides from the nuclear reactor of Mühleberg located at ca.15 km from Lake Biel. Five publications (in refereed journals) directly resulting from this follow-up proposal are in process of publication.
