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.
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.
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.
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.
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.
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.
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.
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. (...)
Quality standards to assess the chemical status of water bodies under the Water Framework Directive are often based on a few standardized laboratory tests and fixed assessment factors for extrapolation to the field situation. If larger data sets including tests with non-standard species are available, a statistical extrapolation approach, the Species Sensitivity Distribution approach (SSD) is applied. For assessing the remaining uncertainty on the SSD, the threshold concentration derived can be compared with data from field monitoring or model ecosystem studies. Taking the priority substance Ni as an example we present the use of microcosms to test the protectiveness of the quality standard derived from laboratory toxicity tests. The study was conducted in 14 microcosms including a natural sediment layer and an overlaying water volume of 750 L located in a greenhouse. After a pre-treatment period for establishing a diverse aquatic community of phytoplankton, zooplankton, periphyton and snails, Ni solution was added to reach concentrations of 6, 12, 24, 48 and 96 micro g Ni/L in two microcosms each. Four microcosms served as untreated controls. To achieve the intended constant exposure over the test period of four months, Ni concentrations were frequently determined in the microcosms and appropriate amounts of nickel solution were added mostly on a daily basis. Parameters known to affect Ni toxicity, i.e. water hardness, pH, and dissolved organic carbon, were also measured. Population abundance and community structure were analysed for difference to the dynamics in the controls. In the microcosms with 48 and 96 micro g Ni/L long-term effects on phytoplankton, rotifers, snails and, due to reduced grazing by snails, indirectly on the periphyton biomass were observed. Only minor, and/or temporary deviations from controls, i.e., for single sampling dates, were found for a few algae taxa at lower concentrations. Because these deviations showed no clear dose-response and were not found at the end of the study they were not seen as adverse effects. However, for the snail (Lymnaea stagnalis), effects on the trend of population development could not be excluded at 24 micro g/L. Thus, the overall No Observed Effect Concentration (NOEC) for a chronic exposure to nickel in this microcosm study was considered to be 12 micro g Ni/L. This NOEC confirms the protectiveness of the quality standard derived from the laboratory single species tests.
Infrared spectroscopy is a powerful technique for the continuous measurement of trace gases in ambient air. A new generation of laser based instruments became available with the development of pulsed, room temperature quantum cascade lasers (RT-QCL) over the last ten years. Their cryogenic free operation is highly important for unattended measurements. However, RT-QCL based systems are often restricted in sensitivity due to the rather broad instrumental linewidth. Furthermore, the limited output power often requires liquid nitrogen cooled detectors to reach the necessary signal to noise ratio. The newest generation of lasers can be operated as continuous wave devices above room temperature (CW-RT-QCL). This is the key to a better spectroscopic performance because of their smaller linewidth, and to Peltier cooled detectors thanks to a significant increase in laser power. Their full potential can, however, only be explored if the quantum cascade laser spectrometer (QCLAS) is fully optimized for these most recent laser devices. The progress of QCLAS is well illustrated by formaldehyde. While this substance was out of reach for cryogenic free laser instruments until now, we expect HCOH to be measurable in ambient air by a novel spectrometer for high-precision trace gas analysis based on continuous wave quantum cascade lasers. HCHO in the atmosphere is one of the key compounds for photochemical reactions leading to the production of radicals and secondary photooxidants. Considering its importance, the database about the distribution of formaldehyde is still limited, which is mainly due to analytical difficulties. Our work will be based on the newest generation of QCLAS based on CW-RT-QCL. Both laser and spectrometer are currently in their final stage of development and, combined, will provide a unique instrument for trace gas analysis. Their first application is planned for continuous measurements of formaldehyde, but other substances (i.e. HNO3, CO, NO2 HONO, HCOOH) may be measured with the same optical platform. This novel QCLAS is a key technology to keep our research groups at the front of current developments in ambient air monitoring, atmospheric chemistry, source identification and source quantification. It is also a powerful infrastructure that will be used in collaboration with many different national and international research groups.
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