Das Projekt "Transport of EINP through soil affected by the dynamics of infiltration flux and particle properties" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Umweltforschung GmbH - UFZ, Department Bodenphysik durchgeführt. In this project we experimentally explore the transport of engineered inorganic nanoparticles (EINP) through soils. This is done for original EINPs and some pre-aged form. Transport of NPs in soil is expected to be different from that of reactive solutes, in that hydrodynamic drag, inertial and shear forces as well as the affinity to water-gas interfaces are expected to be more relevant. Hence, the mobility of EINPs in soil is highly sensitive to the morphology of the porous structure and the dynamics of water saturation.This project provides the pore network structure for natural soils using X-ray micro-tomography to allow for an up-scaling of pore-scale interactions explored by project partners to the scale of soil horizons. The pore structure is represented by a network model suitable for pore scale simulations including the dynamics of water-gas interfaces.Pore network simulations will be compared to column experiments for conservative tracers as well as for unaltered and pre-aged EINPs (obtained from INTERFACE). This includes steady state flow scenarios for saturated (ponding) and unsaturated conditions as well as for transient flow to explore the impact of moving water-gas interfaces. The final goal is to arrive at a consistent interpretation of experimental findings and numerical simulations to develop a module for modelling EINP transfer through soil as a function of particle properties, soil structural characteristics and external forcing in terms of flux boundary conditions.
Das Projekt "Beach sand deposits on the coast of southern Norway as a natural experimental setup to test hypotheses on soil development and luminescence dating" wird vom Umweltbundesamt gefördert und von Universität Hohenheim, Institut für Bodenkunde und Standortslehre durchgeführt. Beach sand deposits are widespread in the area around Sandefjord, at the western coast of the Oslofjord, southern Norway. The age of the deposits continuously increases with elevation, as the area has been subject to steady glacio-isostatic uplift throughout the Holocene. Existing local sea level curves provide age control related to elevation. Thus, the area offers excellent conditions to test hypotheses on soil formation and OSL dating. A chronosequence covering the last 10 000 years will be established. A preliminary study showed that soil formation leads to Podzols within 4300 - 6600 years. Micromorphological analyses suggest that clay illuviation takes place before and below podzolisation. It is hypothesised that clay translocation goes on contemporarily with podzolisation, but at greater soil depth, where the chemical conditions are suitable. This hypothesis will be proved by more detailed micromorphological investigation and chemical analyses. The factors controlling soil forming processes and their rates, will be determined by analyzing elemental composition, primary minerals and clay mineralogy. Preliminary OSL dating tests suggest that the beach sand deposits are OSL dateable despite the high latitude. This hypothesis will be checked by comparing OSL datings to ages derived from the 14C-based sea level curves.
Das Projekt "Die Funktion einer Komponente des autonomen pathways bei der Blühzeitpunktkontrolle bei Arabidospis und Gerste" wird vom Umweltbundesamt gefördert und von Technische Universität Dresden, Lehrstuhl für Molekulare Zellphysiologie und Endokrinologie durchgeführt. We will compare the role of an RNA-binding protein in floral transition in Arabidopsis thaliana and Hordeum vulgare. The RNA-binding protein AtGRP7 promotes floral transition mainly by downregulating the floral repressor FLC via the autonomous pathway. Based on our observation that AtGRP7 affects the steady-state abundance of a suite of microRNA precursors, we will globally compare the small RNA component of the transcriptome during FTi regulation in wild type plants and AtGRP7 overexpressors by deep sequencing. This will extend the knowledge on small RNAs associated with floral transition and provide insights into the regulatory network downstream of this RNA-binding protein. Further, we will address the question how AtGRP7 orthologues function in crop species lacking FLC homologues. A barley line with highly elevated levels of the AtGRP7 orthologue HvGR-RBP1 shows accelerated FTi and preanthesis development when compared to a near-isogenic parent with very low expression of this gene. We will characterize in detail flowering of this line with respect to different photoperiods and its vernalization requirement. We will employ a TILLING approach to further delineate the function of HvGR-RBP1 in flowering. A candidate gene approach to identify downstream targets will provide insights into the signaling pathways through which HvGR-RBP1 influences FTi. This project contributes to the development of a functional cross-species network of FTi regulators, the major strategic aim of the SPP.
Das Projekt "Quantification of active interfaces with respect to dissolved chemicals in unsaturated structured soil" wird vom Umweltbundesamt gefördert und von Helmholtz-Zentrum für Umweltforschung GmbH - UFZ, Department Bodenphysik durchgeführt. 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 "Testing the warming and nitrogen theory of carbon sequestration (BAFU)" wird vom Umweltbundesamt gefördert und von Universität Basel, Botanisches Institut, Abteilung Pflanzenökologie durchgeführt. Atmospheric CO2 enrichment and climatic warming as well as N deposition affect input and output of carbon and nitrogen in soils. This experiment will assess quasi steady state signals of these fluxes and pools by using 'experiments by nature', i.e. established gradients of temperature and N input, the major drivers of NPP and the soil C balance. We will test the hypothesis that soil respiration (R) is driven by net primary production rather than temperature (T) per se. We will further test the hypothesis that enhanced nitrogen input (here naturally simulated by stands composed of nitrogen-fixing trees) will facilitate greater carbon sequestration. By selecting topography-driven 'IPCC T-gradients' across identical bedrock chemistry and macroclimate and high vs. low N input (Alnus vs. control) we will thus complement data obtained by other projects which employ shorter-term manipulative tests. The work will be conducted in the Swiss midlands and the Central Alps, in part using existing infrastructure at Furka pass (ALPFOR). Our project accounts for the growing international concern about oversimplistic projections derived from idealized (first principle based) laboratory type response functions to large-scale projections (Körner et al. 2007). Our project leans on theory which had been developed earlier by Raich and Nadelhoffer (1989). However, since the majority of experimental approaches adopt manipulative experiments (for soil warming experiments see the review by Rustad et al. 2001), which will also be adopted within the Swiss COST 639 consortium, we see an urgent need of complementing these studies by works using natural thermal and N-gradients. A lot of reasoning in terms of ecosystem carbon budgets relies on carbon pools. While these are significant and measured in a series of national and international attempts, they are rarely combined with actual flux measurements or vice versa. Our survey will aggregate process rates (litter production, root production, thickness growth of trees, soil CO2-evaluation) and climate, as well as soil data. Our project contributes primarily to the working group 1 agenda of this COST action.
Das Projekt "Functional morphology and productivity of a tussock grassland in the Bolivian Altiplano" wird vom Umweltbundesamt gefördert und von Universität Basel, Philosophisch-Naturwissenschaftliche Fakultät durchgeführt. Tropical and subtropical high elevation grasslands are generally dominated by tall tussock grasses, a life form that seems to dominante in year round cold climates but otherwise quite different soil moisture regimes, from very wet (New Guinea, New Zealand, Ecuador) to rather dry, even semi-arid, as is the case in the NW-Argentinan and Bolivian Altiplano. The biomass production of these vast areas is largely unknown, since the classical harvesting technique cannot be applied in perennial vegetation without affecting growth. Given the steady increase in land use intensity, such information is needed to estimate the carrying capacity of these vast rangelands. In this thesis, I developed the needed non-destructive tools and applied them for a 30-month productivity analysis in the Bolivian Altiplano. The work was conducted in Sajama National Park at 4250 m elevation. The study plant, Festuca orthophylla, is a tall (up to 1 m, mostly around 60 cm) tussock forming grass that represents more than 90Prozent of all biomass in many parts of the Altiplano, including the study area. Forming clones of initially compact, but later fragmented shape, persisting many decades, this species is characteristic for the appearance of the semi-arid, Andean landscape over thousands of square kilometers at elevations between 3600 and 4600 m a.s.l. As a first step, I analysed the clonal structure, the morphology and biomass allocation in representative tussocks. The core of the theses is related to the tussock biomass production using a demographic approach and land cover data (Chapter 3), followed by an assessment of seasonal leaf dynamics (Chapter 4). In conclusion, our data provide a quantitative characterisation of the architecture and dry matter investment of this dominant Altiplano species, the first year-round productivity estimation for a high-elevation tropical, grassland, and a detailed assessment of leaf dynamics for the rainy and the dry season. In a number of ways the traits exhibited, contrast Festuca orthophylla from other, non-woody, high elevation taxa. In particular, the foliage of these tussocks operates at temperature close to that of the free atmosphere, while at the same time, providing shelter to below-ground shoot meristems. The large amount of dead plant material constrains photosynthetic light interception, and reflects slow rates of decomposition, a likely trade-off of generally poor nutrional quality (Patty et al., 2010), which, in turn, relates to the heavy herbivory pressure. The rates of biomass accumulation per unit of tussock area are quite high, much higher than one would expect in such a semi-arid rangeland. The most plausible explanation is that these tussocks are utilizing a far greater land area for water and nutrient acquisition than represented by their projected canopy area. The space in-between tussocks is, thus, a most likely mechanism explaining these high rates of productivity.
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