Das Projekt "Entwicklung eines mobilen Verfahrens zur Abwasser- und chemikalienfreien Fassadenreinigung mit Niedrigtemperatur-Atmosphärendruckplasmen" wird vom Umweltbundesamt gefördert und von Europäische Forschungsgemeinschaft Reinigungs- und Hygienetechnologie e.V. durchgeführt. Derzeit werden verschmutzte Fassaden meist mit Strahlverfahren gereinigt, bei denen entweder Wasser oder Gemische aus Wasser, Luft und festen Strahlmitteln eingesetzt werden. In Spezialfällen (z.B. bei der Graffitientfernung) werden auch toxikologisch und ökologisch nachteilige organische Lösemittel eingesetzt, wobei aufwändige Zusatzmaßnahmen des Arbeits- und Umweltschutzes erforderlich sind. Ein Nachteil der praxisüblichen wässrigen Strahlverfahren sind die hohen Personal- und Betriebskosten. Derartige Verfahren erfordern hohe Wassermengen, so dass in großem Umfang schadstoffbelastete Abwässer resultieren. Diese dürfen aufgrund der umweltrechtlichen Vorschriften nicht unaufbereitet in die Kanalisation bzw. in die Oberflächengewässer geleitet werden, sondern müssen je nach Schadstoffbelastung zusammen mit den eingesetzten Strahlmitteln aufwändig und zu hohen Kosten aufgefangen und aufbereitet bzw. entsorgt werden. Ferner führt der Einsatz wasserintensiver Fassaden-Reinigungs-verfahren je nach Porosität der Materialien zu starker Durchfeuchtung mit entsprechenden Folgeschäden. Darüber hinaus kann trotz der möglichen Anpassung der Strahlwirkung an Untergrund und Anschmutzung eine Materialschädigung der zu reinigenden Oberfläche durch Abrasion nicht vollständig verhindert werden. Eine Alternative zu den genannten Reinigungsverfahren bietet die Plasmatechnologie. Wie im abgeschlossenen Forschungsprojekt gezeigt, können typische Fassadenmaterialien, wie Klinker, Sandstein, Feinsteinzeug, Marmor, Granit, Eloxal und Edelstahl mit kaltem Atmosphärendruckplasma gereinigt werden. Ein mobiles Abwasser- und chemikalienfreies Reinigungsverfahren, das zugleich materialschonend ist, wurde hiermit entwickelt. Als typische Anschmutzungen wurden Graffitianschmutzungen (Acryl- und Kunstharzlacke) und künstliche Atmosphärenschmutze eingesetzt. Die angeschmutzten Proben wurden einer definierten Bewitterung (abwechselnde UV- Bestrahlung und Betauung) für 30 Tage ausgesetzt. Zur Erzielung einer guten Reinigungswirkung mittels Plasma wurden verschiedene Prozessgase (Druckluft, Argon, Stickstoff) eingesetzt und Prozessparameter variiert, darunter Düsengeometrie, Abstand Düse-Substrat, Vorschubgeschwindigkeit und Anzahl der Überfahrten. Bei Anwendung von Druckluft als Prozessgas wurde unter Einsatz eines hochenergetischen Druckluft-Plasmastrahls unter bestimmten Verfahrensbedingungen ein effektiver Abtrag von schwarzem, grünem und rotem Acryl- und Kunstharzlack, aber auch von Algen und Pilzen von bis zu 100% erreicht. Weißer und silbernen Acryllack konnten hingegen nur zu maximal 70% entfernt werden. Die untersuchten Materialien wurde dabei sowohl mechanisch als auch thermisch nicht geschädigt. Während der Plasmabehandlung wurden relativ niedrige Oberflächentemperaturen von 60 bis 80°C für mineralische bzw. 70° bis 115°C für metallische Substrate gemessen usw
Das Projekt "Tree growth and forest ecosystem functioning in Eurasia under changing climate" wird vom Umweltbundesamt gefördert und von Paul Scherrer Institut durchgeführt. Global climate change will alter the species composition of forests with far reaching consequences for the biogeochemistry of the water, carbon and nitrogen cycles, the sustainability of economic development and even human health. The annual productivity of wood is substantial for the carbon sequestration and budget of the forests in Eurasia. Whereas a number of publications on the climatic influence on tree radial growth exist, little is known about the precise mechanisms of tree-ring formation, timing and rates of their growth, and about the influence of other exogenous factors such as forest fires, permafrost, or logging on biomass accumulation and carbon sequestration. An improved mechanistic understanding will be particularly important with respect to the prediction of future forest response. In the proposed project, we aim to study the influence of a changing climate on trees by analyzing the main factors controlling tree-ring growth in extreme conditions. We will focus our study on forest ecosystems in regions which are very sensitive to climatic changes and where rapid and dramatic environmental and climatic changes can take place: 1) The high latitude permafrost region in Central Siberia (Russia) 2) The semi-arid dry areas in Central Asia (Uzbekistan) 3) The high altitude temperature-sensitive region of the Swiss Alps (Lötschental, Switzerland). The conifer trees growing in these regions could be seriously damaged due to expected future changes in temperature, CO2 and water availability. The thawing of permafrost and increasing drought situation could be key factors influencing forest growth and possible forest decline. Tree ring samples from the above mentioned regions will be considered to analyze the climatic response according to the following approaches: Intra-seasonal dynamics of tree-ring formation will be recorded and correlated with monitored environmental factors, like air and soil temperature and humidity, permafrost depth and the isotope composition of soil water, precipitation, river and stream water. A broad network of dendrochronological data from different research stations will be developed for each region to cover various local conditions. Special attention will be paid to the carbon/water relations of trees by determination of stable isotope ratios of different ecosystem compartments and tree rings. Project partners are Paul Scherrer Institut, Switzerland (PSI), Swiss Federal Research Institute WSL, Switzerland (WSL), V.N.Sukachev Institute of Forest, Krasnoyarsk, Russia (IF) and Samarkand State University, Uzbekistan (UZ).
Das Projekt "Instabilities in alpine Permafrost: strength and stiffness in a warming thermal regime" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule (ETH) Zürich, Institut für Geotechnik durchgeführt. Global climate change in cryogenic regions has dominated the research agenda recently, as investigators seek ways of identifying the hazards to infrastructure in cold regions to establish distinct uncertainties through a risk based consideration of sensitivity and consequences and thereby mitigate the risk of permafrost degradation. The latest IPCC report states that temperature increased at the top of the permafrost layer in the Arctic by up to 3 C since the 1980s. The permafrost base has been thawing at rates of up to 0.04 m/yr, permafrost degradation is causing changes in land surface characteristics and drainage systems and snow cover has decreased in most regions. This has been greatest at lower elevations, e.g. in Switzerland. Melting massive ice or degrading permafrost is becoming increasingly susceptible to causing initiation of slope instabilities and debris flows, having caused the 1997 Val Pola debris flows in the Italian Alps. Recent instabilities in the Vallée du Du Durnand in Valais and the Bérard Rock Glacier in France, both in 2006, emphasise the growing concern. Clear risks were also identified in Turtmanntal, Val d'Anniviers and Mattertal, where some rock glacier features indicated formation of crevasses and depressions at critical positions in the landform and increased risk of failure through the body of the mountain permafrost. Knowledge of the evolving thermal state and internal structure, as well as the response of permafrost soils to a gradual warming cycle, is necessary. This project focuses on the variations of geotechnical response of Alpine permafrost with time and temperature. The time effects are important, since a rock glacier will flow or creep downhill. Landforms have changed in the smaller rock glaciers in the West Alps, where these are particularly sensitive to warming scenarios. Clearly this may lead to instability. The specific goals are: o to investigate artificially frozen soils in the laboratory to understand the relative influences of stresses, soil-ice content, particle size and shape, strain rate and temperature on the strength and stiffness, particularly within the thawing zone, o to obtain equivalent strength and stiffness data from stored (and future) cored samples of Alpine Permafrost and to compare with those from artificial frozen soil, o to establish relationships between key parameters for both artificial and real mountain permafrost, o to test an existing constitutive law to represent the thermo-hydro-mechanical behaviour of Alpine permafrost, o to obtain relevant parameters for future input to the constitutive model and subsequent numerical analysis of the test data.
Das Projekt "Understanding the isotope signal of trees growing on continuous permafrost in northern Siberia" wird vom Umweltbundesamt gefördert und von Paul Scherrer Institut durchgeführt. The main goal of the project is to improve the use of carbon and oxygen isotope ratios in tree-rings as a tool to detect the response of Siberian larch forests on permafrost to the recent climate change. The goal will be achieved by a detailed analysis of the incorporation and fractionation of isotopes in a Siberian forest ecosystem (64 N, 100 E) on a seasonal scale, at an approximately weekly time resolution during the vegetation period. A new approach involving compound-specific isotope analysis of different plant components will be applied to enhance the understanding of post-photosynthetic fractionation and carbon allocation processes. These results will be used to calibrate isotope fractionation transfer models along the leaf and stem. Oxygen isotope values of water samples extracted from soil, leaves and branches will be the basis for a better understanding of the water-use of trees, with a focus on time-lags caused by storage and release of permafrost water. Earlywood and latewood isotope chronologies covering the last 100 years on sites contrasting in permafrost depth will enable the application of the results on longer timescales. This will reveal if the thawing of permafrost and the deteriorating summer drought conditions are the key factors influencing forest growth. The results will be compared to studies conducted in the Alpine region in the Lötschental, where tree growth is also temperature-limited, but where the soil conditions (without permafrost) are very different. Siberian larch forests in the continuous permafrost region are sensitive ecosystems and have been especially exposed to the global warming of the recent decades. These forests are vulnerable, as the vegetation period is short, and water and nutrient availabilities are low. Our previous research on Siberian sites indicated a complex interplay of environmental factors, isotope ratios and tree growth. The t and provoke a risk of an additional radiative forcing of the climate system. 2 century were detected. The permafrost in this region has an important role as a direct water source during summer drought due to extremely low precipitation. Increasing temperatures in the future will enhance the leaf-to-air vapour pressure difference, thus the evaporative demand and water loss of the plants, which may reduce productivity and carbon sequestration of these forests. Furthermore, higher decomposition rates in the uppermost part of soils and accessibility of carbon currently stored in permafrost to microbial degradation could release COthemperature signal in the isotope chronologies was lower than expected, but indications for an increasing drought situation in the 20