Das Projekt "SINCOS: Sinking Coasts - Geosphere, Ecosphere and Anthroposphere of the Holocene Southern Baltic Sea - Part 1.4: Changing sea levels and (semi)terrestrial landscape development in the Baltic Sea coastral area, with special attention to the role of the Darss Sill" wird vom Umweltbundesamt gefördert und von Ernst-Moritz-Arndt-Universität Greifswald, Institut für Botanik und Landschaftsökologie, Lehrstuhl für Landschaftsökologie und Ökosystemdynamik durchgeführt. The research unit SINCOS, established by the Deutsche Forschungsgemeinschaft, has been started in September 2002. The general target is the development of a model of the relation between geo-system, eco-system, climate and socio-economic system for sinking coasts of tideless seas to be developed as an example for the southern Baltic Sea since the Atlantikum. Geoscientists (geologists, geomorphologists, geodesists), biologists (palaeobotanists, palaezoologists), climate researchers and archaeologists will collaborate in order to investigate the cause and effect relation between driving forces (climatic and geological processes) and the response of the natural and social environment in the coastal areas of a transgressive sea. The reconstruction of the Litorina transgression west and east of the Darss sill structure plays the central role. Seven projects under the roof of SINCOS will deal with the acquisition and interpretation of proxy-data in order to reconstruct the history of the southwestern Baltic Sea since 8.000 calendar years BC. In the frame of two projects data will be integrated and models will be developed that mirror the processes of interrelation of different spheres to be investigated. Depending on the varying degree of quantification between measurable variables and qualitative observations models will differ between statistical data exploration and deterministic differential equations. A 4D GIS plays the central role in modelling and data integration. Results will be presented as time-dependent regionalizations of geo-, eco-, and socio-economical parameters. Simulations of future relative sea level change scenarios based on models developed are planned.
Das Projekt "E 1.1: Mathematical modelling of the drying process of tropical fruits including the kinetics of quality decisive attributes" wird vom Umweltbundesamt gefördert und von Universität Hohenheim, Institut für Lebensmittelwissenschaft und Biotechnologie, Fachgebiet Lebensmittel pflanzlicher Herkunft (150d) durchgeführt. The cultivation of fruit trees is a priority option for a sustainable agriculture in tropical mountainous regions of Southeast Asia. However, seasonal overproduction and insufficient access to fresh fruit markets causes high losses. Local processing of dried fruits could have a significant contribution to provide farmers with regular income and is an essential means to improve the micro-nutrient supply. However, local fruit drying methods including pre-treatments with sulphur and boiling in sugar solution cannot retain the typical fruit aroma, colour and micro-nutrients and prevent access to international markets. In addition, high energy consumption and the lack of knowledge of optimum drying parameters increase production costs significantly. To optimise the drying process for tropical fruits in general there is an urgent need to investigate into the impact of drying parameters and drying methods on the kinetics of quality decisive attributes. The development of drying simulation models including the reaction kinetics are therefore an important tool to produce high quality dried fruits at minimum costs and less energy consumption. To meet pre-requisites according to the shape of fruits, mangoes, lychees and unpeeled longans have been chosen for this project as model for cut slices and spheres, respectively. Within a preliminary project (DFG Mu582/3-1/2) the influence of the drying parameters on the quality of sliced mangoes was investigated at stationary conditions. The research work included the determination of drying curves and the quality evaluation of fresh and dried fruits but did not include the kinetics of the quality decisive parameters. In the following, the drying fundamentals of the fruits will be determined or completed. First, based on the drying curves, the physical properties of fruit flesh (diffusion coefficient, heat and mass transfer coefficient) and secondly density, specific heat capacity, thermal and temperature conductivity as well as equilibrium moisture content will be determined using either standard procedures or new methodologies to be developed. For quality analysis, experiments on the functional interaction between drying conditions (temperature, humidity, air velocity), of relevant index enzymes activities (peroxidase POD, polyphenoloxidase, PPO; lipoxygenase, LOX) and the quality determining criterions (flavour, aroma, texture, colour, vitamin content) will be followed by quality evaluation and optimising the drying conditions. Using adequate simulation programmes, the mathematical modelling of the drying process including the enzyme kinetics and the temporal changes of quality attributes will lead first to simulate the drying process for a single fruit and further on to simulations of stationary high-temperature drying processes as well as solar drying processes at unsteady conditions. The development and validation of the simulation model based on the results of the drying tests including an economical analysis
Das Projekt "Implications of the biogenic character on aquatic food chain accumulation of elemental selenium" wird vom Umweltbundesamt gefördert und von Fachhochschule beider Basel - Nordwestschweiz durchgeführt. Selenium is a double edged chemical element, since it is both essential yet highly toxic. Besides its high acute toxicity, selenium is characterized to be strongly bioconcentrated from dissolved selenium species (selenite, selenate, selenoaminoacids) in aquatic primary producers and further biomagnified during food chain transfer. In consequence, water borne selenium concentrations of as little as 2 myg / L have been documented to cause severely adverse effects on top predators such as water birds and fish. Although the ecotoxic impact was first noticed in the early 1980s, to date no definitive solution has been found to remediate selenium contaminated drainage and waste waters. Due to the water insolubility of elemental selenium, the dogma that 'elemental selenium is not bioavailable and not toxic' dominates current scientific literature and forms the basis for various remediation approaches using microorganisms to convert selenium oxyanions to elemental selenium. However, a number of considerations and recent studies suggest that the dogma might only be true for 'bulk' elemental selenium, yet not for microbially formed, so called biogenic selenium. Biogenic differs from bulk elemental selenium considerably regarding its physico-chemical properties. Biogenic elemental selenium consists of nanometer sized spheres, which do not crystallize to larger particles of trigonal elemental selenium, the thermodynamically stable allotrope. The latter is due to stabilization by proteins associated with the particles. As a consequence, biogenic elemental selenium does not settle yet remains in waters as a colloidal suspension, thus being subject to uptake by biota. Although the general bioavailability of biogenic elemental selenium has been proven, it has not been studied in detail, in particular not in aquatic environments. We aim at quantifying acute and chronic toxicity in the model organism Daphnia magna, elucidating the underlying mechanism of toxicity. Furthermore, we will quantify biogenic elemental selenium uptake, depuration and biotransformation to proteinous forms (the species most relevant for trophic transfer). Thus we will be able to deliver an improved model of selenium food chain transfer in aquatic environments, the basis for appropriate selenium risk assessment. During the course of the proposed research, such questions as the following will be answered: - Is biogenic elemental selenium bioavailable and / or toxic to Daphnia magna? Which are the mechanisms underlying toxicity? - To which extent is biogenic selenium biotransformed to proteinous (highly bioaccumulative) species? Does biogenic elemental selenium represent a significant entrance port for selenium at base of aquatic food chain?