Das Projekt "Ecotoxicology of Organotin compounds" wird/wurde ausgeführt durch: Universität Frankfurt am Main, Institut für Ökologie, Evolution und Diversität, Abteilung Aquatische Ökotoxikologie.Organotin and especially butyltin compounds are used for a variety of applications, e.g. as biocides, stabilizers, catalysts and intermediates in chemical syntheses. Tributyltin (TBT) compounds exhibit the greatest toxicity of all organotins and have even been characterized as one of the most toxic groups of xenobiotics ever produced and deliberately introduced into the environment. TBT is not only used as an active biocidal compound in antifouling paints, which are designed to prevent marine and freshwater biota from settlement on ship hulls, harbour and offshore installations, but also as a biocide in wood preservatives, textiles, dispersion paints and agricultural pesticides. Additionally, it occurs as a by-product of mono- (MBT) and dibutyltin (DBT) compounds, which are used as UV stabilizer in many plastics and for other applications. Triphenyltin (TPT) compounds are also used as the active biocide in antifouling paints outside Europe and furthermore as an agricultural fungicide since the early 1960s to combat a range of fungal diseases in various crops, particularly potato blight, leaf spot and powdery mildew on sugar beet, peanuts and celery, other fungi on hop, brown rust on beans, grey moulds on onions, rice blast and coffee leaf rust. Although the use of TBT and TPT was regulated in many countries world-wide from restrictions for certain applications to a total ban, these compounds are still present in the environment. In the early 1970s the impact of TBT on nontarget organisms became apparent. Among the broad variety of malformations caused by TBT in aquatic animals, molluscs have been found to be an extremely sensitive group of invertebrates and no other pathological condition produced by TBT at relative low concentrations rivals that of the imposex phenomenon in prosobranch gastropods speaking in terms of sensitivity. TBT induces imposex in marine prosobranchs at concentrations as low as 0,5 ng TBT-Sn/L. Since 1993, for the littorinid snail Littorina littorea a second virilisation phenomenon, termed intersex, is known. In female specimens affected by intersex the pallial oviduct is transformed of towards a male morphology with a final supplanting of female organs by the corresponding male formations. Imposex and intersex are morphological alterations caused by a chronic exposure to ultra-trace concentrations of TBT. A biological effect monitoring offers the possibility to determine the degree of contamination with organotin compounds in the aquatic environment and especially in coastal waters without using any expensive analytical methods. Furthermore, the biological effect monitoring allows an assessment of the existing TBT pollution on the basis of biological effects. Such results are normally more relevant for the ecosystem than pure analytical data. usw.
Das Projekt "Forschergruppe (FOR) 986: Structural Change in Agriculture, How should Model Linkages be designed to analyze the Effects of Global Agricultural Trade Liberalization at the Farm Level?" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Johann Heinrich von Thünen-Institut Bundesforschungsinstitut für Ländliche Räume, Wald und Fischerei, Institut für Betriebswirtschaft.In the last decades agricultural policy has gained increasingly in complexity. Nowadays it influences the food and agricultural sector from the global market down to the farm level. Widespread research questions, like the impact of the WTO negotiations on the farm structure, most often require comprehensive modeling frameworks. Thus, different types of models are utilized according to their comparative advantages and combined in a strategically useful way to more accurately represent micro and macro aspects of the food and agricultural sector. Consequently, in recent years we have seen an increase in the development and application of model linkages. Given this background, the overall objective of this subproject is a systematic sensitivity analysis of model linkages that gradually involves more and more characteristics of the linkage and the corresponding transfer of results between models. In addition, the project aims to answer the following specific question: How does structural change at the farm level influence aggregate supply and technical progress? Under which conditions is it possible to derive macro-relationships from micro-relationships? How does the aggregation level influence the model results and how can possible problems be overcome? This procedure is used to quantify the effects and to derive conditions for optimal interaction of the connected models. The analysis is based on the general equilibrium model GTAP (Global Trade Analysis Project) and the farm group model FARMIS (Farm Modelling Information System) which are employed in conjunction to analyze the effects of WTO negotiations on the farm level.
Das Projekt "Effects of canopy structure on salinity stress in cucumber (Cucumis sativus L.)" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Hochschule Geisenheim University, Zentrum für Wein- und Gartenbau, Institut für Gemüsebau.Salinity reduces the productivity of cucumber (Cucumis sativus L.) through osmotic and ionic effects. For given atmospheric conditions we hypothesize the existence of an optimal canopy structure at which water use efficiency is maximal and salt accumulation per unit of dry matter production is minimal. This canopy structure optimum can be predicted by integrating physiological processes over the canopy using a functional-structural plant model (FSPM). This model needs to represent the influence of osmotic stress on plant morphology and stomatal conductance, the accumulation of toxic ions and their dynamics in the different compartments of the system, and their toxic effects in the leaf. Experiments will be conducted to parameterize an extended cucumber FSPM. In in-silico experiments with the FSPM we attempt to identify which canopy structure could lead to maximum long-term water use efficiency with minimum ionic stress. The results from in-silico experiments will be evaluated by comparing different canopy structures in greenhouses. Finally, the FSPM will be used to investigate to which extent the improvement of individual mechanisms of salt tolerance like reduced sensitivity of stomatal conductance or leaf expansion can contribute to whole-plant salt tolerance.
Das Projekt "Pseudoallergische Reaktionen auf Pharmaka und Nahrungsmittelzusatzstoffe" wird/wurde ausgeführt durch: Forschungsinstitut Borstel.In Vivo und in vitro Verabreichung von Nahrungsmittelzusatzstoffen (Tartrazin, Gelborange, Amaranth, Benzoesaeure, Sorbinsaeure, Na-Disulfit, K-Disulfit, Glutamat) und von Nahrungsmitteln (Ei, Milch, Nuesse, Fisch, Rohkost, Fleisch, Mehlsorten) an Patienten mit Verdacht auf entsprechende Unvertraeglichkeiten. Symptome: Kopf- und Bauchschmerzen, Asthma, Rhinitis, Diarrhoe, Urticaria, anaphylaktischer Schock. Mit Hilfe der in vitro Provokationen werden Korrelationen zwischen Mediatorenprofilen und der klinischen Symptomatologie hergestellt. Ziel der Untersuchung: Etablierung eines validen, nicht invarsiven, den Patienten nicht gefaehrdenden diagnostischen Verfahrens zur Objektivierung der nahrungsmittelinduzierten pseudoallergischen Reaktionen.
Das Projekt "Alpine plant ecology" wird/wurde ausgeführt durch: Universität Basel, Botanisches Institut, Abteilung Pflanzenökologie.Our long term activities aim at a functional understanding of alpine plant life. Overall our research shifted gradually from studying resource acquisition (e.g. photosynthesis) toward resource investment and questions of developement. As with treeline, sink activity seems to be the major determinant of growth. A common misconception associated with alpine plant life finds its expression in the use of the terms 'stress' and 'limitation'. See the critique in: Körner C (1998) Alpine plants: stressed or adapted? In: Press MC, Scholes JD, Barker MG (eds.) Physiological Plant Ecology. Blackwell Science , 297-311. Ongoing experimental work: The influence of photoperiod on growth and development in high elevation taxa (Ph.D. by Franziska Keller in cooperation with the Dept. of Geography, University of Fribourg). We test, whether and which species are responsive to earlier snow melt. It appears there exists a suite of different sensitivities, suggesting biodiversity shifts. We also tested the influence of nutrient addition on high elevation pioneer plants and run a longer term project on the interactive effect on sheep tramplng, nitrogen deposition and warming as part of the Swiss National Project NFP 48. A Europe-wide assessment of ground temperatures in alpine grassland is part of ALPNET (see associated organisations). The assessment provides a basis for comparing biodiversity in alpine biota from 69 to 37 degree of northern latitude. (Nagy et al. (2003) Ecological Studies, Vol. 167. 577 p. Springer, Berlin). A synthesis of research in functional ecology of alpine plants over the past 100 years was published in 1999.
Das Projekt "Assessment of satellite constellations for monitoring the variations in earth s gravity field" wird/wurde gefördert durch: European Space Agency, European Space Research and Technology Centre. Es wird/wurde ausgeführt durch: Universität Stuttgart, Geodätisches Institut.More than a decade has passed since the launch of the GRACE satellite mission. Although designed for a nominal mission lifetime of 5 years, it still provides valuable science data. An eventual systems failure and, thus, mission termination is expected any time soon, though. Despite a relative low spatial and temporal resolution, the monthly gravity fields have proved an invaluable and novel parameter set in several geoscience disciplines, allowing new research venues in the study of Global Change phenomena. The hydrological cycle is now subject to quantification at continental scales; the state of the cryosphere, particularly ice sheet melting over Greenland and Antarctica, can be monitored; and steric effects of sea-level change have become separable from non-steric ones. The enormous success of the mission has driven the need for continuation of monitoring mass changes in the Earth system. Indeed, a GRACE Follow-On (GFO) mission has been approved for launch in August 2017. Like its predecessor it will consist of two satellites flying en echelon with intersatellite K-Band ranging as the main gravitational sensor. Despite a number of planned technological improvements, including a laser link as demonstrator, GFO will mostly be based on GRACE heritage. Given a similar orbit configuration and a similar systems setup, the quality of eventual gravity field products can be expected to be in the same range as the current GRACE products. To guarantee the continuation of such successful gravity field time series ESA has embarked several years ago on a long term strategy for future gravity field satellite missions, both in terms of technology development and in terms of consolidating the user community. Scientists from academia and industry held a workshop on The Future of Satellite Gravimetry at ESTEC premises, 12-13 April 2007, (RD-9). Similar workshops have been organized by other organizations, e.g. the joint GGOS/IGCP565 workshop Towards a Roadmap for Future Satellite Gravity Missions in Graz, September 30 - October 2, 2009. ESA furthermore played a key role in consolidating the international user community by funding a series of study projects, cf. (RD-1) to (RD-5). Similar projects have been funded and conducted at national level, e.g. the German BMBF-funded Geotechnologies III project Concepts for future gravity field satellite missions (PI: N. Sneeuw). These studies, together with GRACE experience, have provided a clear understanding of the current limitations of a GRACE-type mission. In particular the limitations in sampling and sensitivity of a single pair of satellites with in-orbit in-line sensitivity are well documented. At the same time, these studies have shown the design options and a roadmap towards a next generation gravity field mission.
Das Projekt "Rundholzqualität Douglasienprovenienzen, Adaptation of forest trees to climatic change - climate sensitive growth dynamics of Douglas-fir provenances" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft. Es wird/wurde ausgeführt durch: Forstliche Versuchs- und Forschungsanstalt Baden-Württemberg.The main objective of the project is to determine growth sensitivity, elasticity, and resilience of Douglas-fir provenances to climatic alterations, in particular drought events. To differentiate between the impact of site and genetics, samples from experiments will be analyzed, where identical provenances are planted at different sites. Major research scopes are: Investigating the impact of weather on intra-annual growth patterns We will determine how weather variations affect the provenances' growth. The focus will be on intra-annual variations in wood anatomy and density. A dendrometer study will complement the retrospective analyses to monitor changes in stem hydraulic status and to trace the seasonal timing of growth processes. Fitting genotype- and climate-sensitive growth models for a growth simulation system Retrospective inter-annual growth address long-term trends as well as the effect of distinct climate events on inter-annual growth responses. The goal is to build provenance- and climate-sensitive growth models that can be integrated into a growth simulation system. The assessment of growth responses to drought will be tested and interpreted against the results of the partner projects within the general research concept 'adaptation of forest trees to climatic change - diversity of drought responses in Douglas-fir provenances': P1 (genes), P2 (stable isotopes), and P4 (isoprenoids). A major contribution of our project is to provide the partner projects with research opportunities in the adult stands of the provenance experiments.
Das Projekt "Internationales Graduiertenkolleg (IRTG) 1070: Modellierung von Stoffflüssen und Produktionssystemen für eine nachhaltige Ressourcennutzung in intensiven Acker- und Gemüsebausystemen in der nordchinesischen Tiefebene' (769), SP 2.3 Decision support systems for weed management in North China Plain production systems" wird/wurde gefördert durch: Deutsche Forschungsgemeinschaft / Ministry of Education of the People's Republic of China. Es wird/wurde ausgeführt durch: Universität Hohenheim, Institut für Tropische Agrarwissenschaften (Hans-Ruthenberg-Institut) (490), Fachgebiet Agrarökologie der Tropen und Substropen (490f).Wide applications in Europe show that weed management strategies can be considerably improved when computerized expert systems, decision models and population-dynamic models are applied. If these management systems are transferred and adapted to the specific production systems of the North China Plain, herbicide use can be significantly reduced and the evolution of persistent weed populations in the major arable crops can be avoided. The main objective of this subproject will be to create efficacy-based models analyzing herbicide performance in major crops and to create population-based models for herbicide use analyzing the yield losses caused by weed competition. For these models it is necessary to determine the sensitivity of major weed species to herbicides and to explore the potential of reduced dose rates for herbicide use. Furthermore it is necessary to investigate weed management practices combining preventive (timing of seeding, crop rotation and tillage) and direct methods (chemical and physical methods) of weed control. For population dynamic models it is necessary to determine long-term economic weed threshold estimating the changes in the soil seed bank. Finally both models will be combined in a decision support system for weed control in North China Plain Production Systems. The applicability of this decision support system will be tested in field experiments.
Das Projekt "Quantification of ice content in mountain permafrost based on geophysical data and simulated annealing" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: University of Fribourg, Geosciences Departement, Geography Unit.Current and future global warming will cause the degradation of mountain permafrost, which may strongly influence the stability of permafrost slopes or rock walls with potentially hazardous consequences. Due to the strong heterogeneity of both the thermal regime and the ground composition of mountain permafrost, its response to atmospheric forcing can however be highly variable for different landforms and within short distances. The spatial distribution of ice and liquid water is important for determining the sensitivity of a specific permafrost occurrence to climate change because of their large influence on the pace of temperature changes (by effects of latent heat) and their importance for geotechnical properties of the ground. Detailed knowledge of the material properties and internal structures of frozen ground is therefore an important prerequisite to determine the sensitivity of permafrost to climate change. Except for the active layer ice and water contents and their temporal and spatial variability usually cannot be measured directly. Geophysical methods are sensitive for the ice and liquid water content in the ground. With the proposed collaboration, two similar but complementary approaches to quantify the composition of the ground based on 2D sections of geophysical data will be combined for an improved determination of ice and water contents in permafrost regions. The so-called 4-phase model (4PM) is based on two simple petrophysical relationships for electrical resistivity and seismic velocity and estimates volumetric fractions of ice, water, and air within the pore volume of a rock matrix by jointly using complementary data sets from electric and seismic measurements. Due to inherent ambiguities in the model it is still restricted to specific cases and often allows only a rough estimation of the phase fractions. Major drawbacks of the current 4PM comprise the unsatisfactory discrimination between rock and ice and its under-determinedness, requiring the prescription of the porosity and further parameters. The so-called RSANN model (developed and used by the host institution) uses the technique of simulated annealing (a Monte-Carlo-type stochastic simulation approach) as an optimization tool for the integration of electrical resistivity and P-wave velocity to derive 2D sections of porosity, water saturation and volumetric water content. The simulated annealing technique allows - due to its iterative procedure - more parameters to be predicted instead of being prescribed as in the 4PM. The objective of the proposed collaboration is to combine the advantages of the two algorithms (4PM and RSANN) to overcome the shortcomings of the 4PM in order to improve the reliability of the determined ice and liquid water contents. (...)
Das Projekt "PAGES (Past Global Changes International Project)" wird/wurde gefördert durch: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung. Es wird/wurde ausgeführt durch: PAGES International Project Office.The PAGES (Past Global Changes) project, including the PAGES International Project Office in Bern, is funded by the Swiss and U.S. National Science Foundations. The current four-year grant runs from 2006-2010. PAGES was founded in 1991 and works to coordinate international paleoscience research, communicate with the paleoscience community, and integrate past global change scientists from around the world into an international network OBJECTIVES AND METHODS: PAGES is a core project of the International Geosphere Biosphere Program (IGBP) and deals with the Earth's climatic and environmental history from the last few 100 years to several 100,000 years. The primary objective of PAGES is to improve our understanding of past climate and environmental change. SCIENTIFIC AREAS OF INTEREST: While PAGES itself is not a research institution, it helps to identify overarching issues in past global change science and ensure that they are addressed in a coherent manner. Four sets of questions of prime current interest will be targeted by PAGES during the coming years: 1. Climate Forcing and Sensitivity: What is the history of the main climate forcing factors (changes in solar irradiation due to changes in the Earth orbit, changes in solar irradiance due to variability in solar activity, variability of greenhouse gas concentration in the atmosphere, influence of volcanic activity, etc.) and the sensitivity of the climate system to these forcings? In what precise sequence have changes in forcings, surface climate, and ecological systems occurred? 2. Regional Climate Variability: How have global climate and the Earth's natural environment changed in the past? What are the main modes of variability that operated at different timescales, and how do they relate to each other and to the mean state of the climate system? 3. Earth System Dynamics: How have different parts of the Earth System interacted to produce climatic and environmental feedbacks on regional and global scale? What are the causes and thresholds of rapid transitions between quasi-stable climatic and environmental states, in particular on timescales that are relevant to society? How reversible are these changes? 4. Past Human-Climate-Ecosystem Interactions: To what extent and since when has human activity modified climate and the global/regional environment? How can human induced change be disentangled from natural responses to external forcing mechanisms and internal system dynamics? These questions are addressed through organized scientific activities under the umbrella of PAGES. The activities are carried out by the worldwide past global change community, the PAGES Scientific Steering Committee and the PAGES IPO, often in collaboration with other global change programs.
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