Das Projekt "Soil N dynamics as affected by different land use in Western and Southern China" wird vom Umweltbundesamt gefördert und von Technische Universität Dresden, Institut für Bodenkunde und Standortslehre durchgeführt. The aim of the research project is to quantify the stocks and turnover of soil nitrogen in Western and Southern China as dependent from soil structure and land use. Key soil characteristics are determined at representative sites with regional specific land use and degradation status. The investigations will follow a land use gradient of natural forests, arable and pasture soils, the latter ones considering different degradation and rehabilitation status. The actual and potential soil nitrogen turnover will be horizon-wise quantified and related to soil structure and land use impacts. Beside mineral nitrogen, also preliminary organic N compounds using physical and chemical extraction will be detected. Parameters for the investigations are, beside total C and N stocks and distribution, gross and net N mineralization, nitrification, microbial biomass C and N and microbial respiration and indicators for soil N turnover like active N pools and light fraction of organic matter. In the last phase the structure of the soil microbial microbial community will be determined and related to indicators of nitrogen status and efficiency. The research activities will be carried out in close co-operation with the Institute for Soil and Water Conservation/ Yangling University at loess soils and the Nanjing Institute for Soil Science/ Chinese Academy for Science in Nanjing at red soil sites.
Das Projekt "Calcium cycle for efficient and low cost CO2 capture in fluidized bed systems (C3-CAPTURE)" wird vom Umweltbundesamt gefördert und von Universität Stuttgart, Fakultät für Energietechnik, Institut für Verfahrenstechnik und Dampfkesselwesen durchgeführt. Objectives: The project aims on developing a dry CO2 capture system for atmospheric and pressurized fluidized bed boilers. The atmospheric option will be developed towards a pilot plant application. For the pressurized option the project seeks for a proof of principle to determine if the advantages of a pressurized capture system can balance the problems known from existing PFBC systems. The quantifiable objectives are: - Low CO2 capture costs (less than 20 Euro/t for atmospheric, less than 12 Euro/t for pressurized sy stems) - Acceptable efficiency penalty for CO2 capture (less than about equal to 6 percent nel). - greater than 90 percent carbon capture for new power plants and greater than 60 percent for retrofitted existing plants - A purge gas stream containing greater than 95 percent CO2 - A solid purge usable for cement production - Sim ultaneous sulphur and CO2 removal with sulphur recovery option Approach: Limestone is a CO2 carrier. The CO2 can be released easily in a conventional calcination process, well known in the cement and lime industry. By integrating a closed carbonation/calc ination loop in the flue gas of a conventional CFB-boiler, the CO2 in the flue gas can be removed. The heat required for calcination is released during carbonation and can be utilised efficiently (high temperature) in the steam cycle of the boiler. Concent rated CO2 can be generated when using oxygen blown calcination. Because the fuel required for supplying heat for calcination is only a fraction of the total fuel requirements, the required oxygen is only about 1/3 of the oxygen required for oxyfuel process es. The work programme: 1.Definition of the technical and economic boundary conditions 2.Selection and improvement of sorbent materials 3.Lab scale and semi-technical scale process development (experimental work) 4.Technical and economic evaluation 5.Des ign of a 1 MWth Pilot plant.
Das Projekt "Plant induced weathering of minerals in the subsoil - release of 'non-exchangeable' potassium from 2:1 layer minerals (TransMinK)" wird vom Umweltbundesamt gefördert und von Universität Halle-Wittenberg, Institut für Agrar- und Ernährungswissenschaften, Professur für Bodenkunde und Bodenschutz durchgeführt. The proposal addresses the potential of subsoil to contribute to K nutrition of crops. More specifically we will address the processes controlling release of K from interlayer of 2:1 clay minerals as this is expected to be the dominant K fraction in the subsoil. While it has been shown in the past that this so called 'non-exchangeable' K can be released due to root activity, there are controversial results concerning the role of soil solution K concentration in the rhizosphere required to trigger the process. Likewise little information is available about the concentration dynamics of other cations (NH4, Ca) in the rhizosphere and their impact on K release and vermiculitization supposed to be associated with this process. Model studies with substrate from the central field trial will be conducted in compartment systems equipped with micro suction cups. The measurement of dynamic changes of soil solution composition with increasing distance from the root surface will be combined with investigations of changes in mineralogy by XRD, TEM and SEM-EDX. Changes of mineralogy as a result of plant induced K release from interlayer will also be studied on bulk soil and rhizosphere samples collected within the central field and the central microcosm experiment and with mineral bags exposed in the field during a cropping cycle. Finally, X-ray CT will be used to access changes in soil texture, i.e. clay distribution around roots and the temporal spread of roots in biopores which is a prerequisite for K uptake from such structures.
Das Projekt "14C content of specific organic compounds in subsoils" wird vom Umweltbundesamt gefördert und von Universität zu Köln, Institut für Geologie und Mineralogie durchgeführt. Organic matter (OM) composition and dynamic in subsoils is thought to be significantly different from those in surface soils. This has been suggested by increasing apparent 14C ages of bulk soil OM with depth suggesting that the amount of fresh, more easily degradable components is declining. Compositional changes have been inferred from declining ä13C values and C/N ratios indicative for stronger OM transformation. Beside these bulk OM data more specific results on OM composition and preservation mechanisms are very limited but modelling studies and results from incubation experiments suggest the presence and mineralization of younger, 'reactive carbon pool in subsoils. Less refractory OM components may be protected against degradation by interaction with soil mineral particles and within aggregates as suggested by the very limited number of more specific OM analysis e.g., identification of organic compound in soil fractions. The objective of this project is to characterize the composition, transformation, stabilization and bioavailability of OM in subsurface horizons on the molecular level: 1) major sources and compositional changes with depth will be identified by analysis of different lipid compound classes in surface and subsoil horizons, 2) the origin and stabilization of 'reactive OM will be revealed by lipid distributions and 14C values of soil fractions and of selected plant-specific lipids, and 3) organic substrates metabolized by microbial communities in subsoils are identified by distributional and 14C analysis of microbial membrane lipids. Besides detailed analyses of three soil profiles at the subsoil observatory site (Grinderwald), information on regional variability will be gained from analyses of soil profiles at sites with different parent material.
Das Projekt "The fate of phosphorus in forest and treeline ecosystems in Ecuador" wird vom Umweltbundesamt gefördert und von Universität Tübingen, Fachbereich Geowissenschaften, Forschungsbereich Geographie durchgeführt. Even remote areas such as tropical montane forests suffer from continuously high atmospheric nitrogen (N) and phosphorus (P) deposition. In studies on ecosystem responses to atmospheric nutrient deposition, P cycling has played an underrated role compared to N, although P is thought to limit organism growth in main parts of the Tropics. Furthermore, the responses of tropical montane forests to atmospheric nutrient deposition might depend on the predicted climate change i.e., shifts in temperature and precipitation. Altitudinal gradients represent an ideal means to study environmental changes in tropical montane forests in southern Ecuador, because climate scenarios and unpublished trends in longer-term climate data predict increasing temperatures and decreased moisture which parallels the altitudinal gradient from 4000 m to 1000 m asl.Previous experiments, including the NUMEX experiment in Ecuador, showed that the main proportion of P added to forests to simulate atmospheric deposition was retained in soil. While total P pools in soil respond slowly to low P addition rates, the biological and geochemical processes underlying retention in the organic layer or in soil are expected to react faster. Our overarching objective is to assess the fate of fertilized P in the organic layer and in mineral soil and to elucidate the processes involved in P cycling in soil (immobilization and release rates by microorganisms, sorption/desorption, precipitation/dissolution) along the NUMEX-X altitudinal gradient (1000, 2000, 3000, 4000m; the latter including a Polylepis and a Páramo ecosystem). We will assess P fractions in soil and use a combination of 33P tracer studies and incubation experiments to disentangle biological and geochemical processes controlling P retention. The mechanistic understanding gathered by this proposal is crucial for predictions of ecosystems responses to the continuously high atmospheric N (and P) deposition, because single mechanisms might respond differently (and oppositionally) in the long run. Because the processes involved in P cycling are expected to respond faster to environmental changes than e.g., P pools in soil, these different responses are an essential basis to evaluate effects of environmental change and finally, to develop early-warning ecosystem indicators for environmental change.
Das Projekt "Sub project: Quantitative Reconstruction of the Neogene East and West Antarctic Ice Sheet History from Drift Sediments (ODP Leg 178 and Leg 188): A Synthesis" wird vom Umweltbundesamt gefördert und von Universität Bremen, Zentrum für marine Umweltwissenschaften durchgeführt. The proposed synthesis project aims to quantify the Antarctic ice sheet history of the last 10 Ma. With new statistical tools we will isolate and quantify the 'ice factor' in fine-fraction grain-size distribution data from Antarctic deep-sea drift deposits. In our preparatory work we showed that the sedimentary Antarctic drift bodies are continuous ice archives with a direct link in their built-up history at the continental rise to ice advances to the shelf break. Quantification of the ice volume is therefore possible, since the relative ice-cover to - volume ratio is known from models. In a four step approach we will complete the existing sample collection of Site 1095, increase its time resolution and analyse the recovered data sets with the end-member modeling method. Second step is the validation of the local data set to a regional scale by incorporating samples of a control Site (Site 1101) on a nearby drift. Thirdly we will prepare and analyse samples from a E-Antarctic drift (Site 1165) for a in-depth E-W ice sheet history comparision. During the synthesis phase of the project the new proximal data set will be correlated to a new global isotope -Ca/Mg based ice volume record contributed by our cooperation partners. These are three important reasons to start with the proposed research now: High social relevance of the expected data..., free access to the samples since the one year ODP moratorium for both ODP legs has passed, and the availability of abundant ancillary data from other working groups.
Das Projekt "Wind tunnel investigations on riming of ice particles: Retention of water-soluble organics and the influence of turbulence on the growth of graupels." wird vom Umweltbundesamt gefördert und von Johannes Gutenberg-Universität Mainz, Institut für Physik der Atmosphäre durchgeführt. In recent years, gaseous and particulate organic species in the atmosphere have received increased attention. Organic compounds are found in cloud and rain water as well as in snow samples. However, the removal processes underlying their scavenging is not adequately enough understood such that these are amenable for integration in numerical models. One possibility via the ice phase would be the retention of organics during riming, i.e. the deposi-tion of super-cooled water droplets on ice particles. During this process, the organic species (or fractions of their amounts) can be transferred into and retained by the ice phase while another fraction is released back into the gas phase. These fractions will be investigated and quantified in wind tunnel experiments where freely floating ice particles and snow flakes are exposed to clouds of supercooled droplets containing organic substances of atmospheric significance. As the most abundant water-soluble organics in cloud water are carboxylic ac-ids and aldehydes the proposed experiments mainly extend over these groups. Another topic of great interest is the influence of turbulence on microphysical processes. The collisional growth of cloud droplets is significantly enhanced by turbulence; therefore, similar results are expected in the case of riming as an analogous process in the ice phase. The determination of the growth rate of ice particles by riming under turbulent conditions is necessary for the - so far not yet available - formulation of more realistic collection kernels (in comparison to the laminar case) for the modeling of cloud physics and chemistry.
Das Projekt "Forschergruppe (FOR) 1806: The Forgotten Part of Carbon Cycling: Organic Matter Storage and Turnover in Subsoils (SUBSOM)" wird vom Umweltbundesamt gefördert und von Universität Bochum, Geographisches Institut, Arbeitsgruppe Bodenkunde und Bodenökologie durchgeführt. We are currently facing the urgent need to improve our understanding of carbon cycling in subsoils, because the organic carbon pool below 30 cm depth is considerably larger than that in the topsoil and a substantial part of the subsoil C pool appears to be much less recalcitrant than expected over the last decades. Therefore, small changes in environmental conditions could change not only carbon cycling in topsoils, but also in subsoils. While organic matter stabilization mechanisms and factors controlling its turnover are well understood in topsoils, the underlying mechanisms are not valid in subsoils due to depth dependent differences regarding (1) amounts and composition of C-pools and C-inputs, (2) aeration, moisture and temperature regimes, (3) relevance of specific soil organic carbon (SOC) stabilisation mechanisms and (4) spatial heterogeneity of physico-chemical and biological parameters. Due to very low C concentrations and high spatio-temporal variability of properties and processes, the investigation of subsoil phenomena and processes poses major methodological, instrumental and analytical challenges. This project will face these challenges with a transdisciplinary team of soil scientists applying innovative approaches and considering the magnitude, chemical and isotopic composition and 14C-content of all relevant C-flux components and C-fractions. Taking also the spatial and temporal variability into account, will allow us to understand the four-dimensional changes of C-cycling in this environment. The nine closely interlinked subprojects coordinated by the central project will combine field C-flux measurements with detailed analyses of subsoil properties and in-situ experiments at a central field site on a sandy soil near Hannover. The field measurements are supplemented by laboratory studies for the determination of factors controlling C stabilization and C turnover. Ultimately, the results generated by the subprojects and the data synthesized in the coordinating project will greatly enhance our knowledge and conceptual understanding of the processes and controlling factors of subsoil carbon turnover as a prerequisite for numerical modelling of C-dynamics in subsoils.
Das Projekt "The effect of elevated atmospheric CO2 concentration on gross nitrogen dynamics, plant N-uptake and microbial community dynamics in a permanent grassland" wird vom Umweltbundesamt gefördert und von Universität Gießen, Institut für Pflanzenökologie (Botanik II) durchgeführt. To predict ecosystem reactions to elevated atmospheric CO2 (eCO2) it is essential to understandthe interactions between plant carbon input, microbial community composition and activity and associated nutrient dynamics. Long-term observations (greater than 13 years) within the Giessen Free Air Carbon dioxide Enrichment (Giessen FACE) study on permanent grassland showed next to an enhanced biomass production an unexpected strong positive feedback effect on ecosystem respiration and nitrous oxide (N2O) production. The overall goal of this study is to understand the long-term effects of eCO2 and carbon input on microbial community composition and activity as well as the associated nitrogen dynamics, N2O production and plant N uptake in the Giessen FACE study on permanent grassland. A combination of 13CO2 pulse labelling with 15N tracing of 15NH4+ and 15NO3- will be carried out in situ. Different fractions of soil organic matter (recalcitrant, labile SOM) and the various mineral N pools in the soil (NH4+, NO3-, NO2-), gross N transformation rates, pool size dependent N2O and N2 emissions as well as N species dependent plant N uptake rates and the origin of the CO2 respiration will be quantified. Microbial analyses will include exploring changes in the composition of microbial communities involved in the turnover of NH4+, NO3-, N2O and N2, i.e. ammonia oxidizing, denitrifying, and microbial communities involved in dissimilatory nitrate reduction to ammonia (DNRA). Stable Isotope Probing (SIP) and mRNA based analyses will be employed to comparably evaluate the long-term effects of eCO2 on the structure and abundance of these communities, while transcripts of these genes will be used to target the fractions of the communities which actively contribute to N transformations.
Das Projekt "Linking micro-aggregation to the sequestration of organic pollutants in soil" wird vom Umweltbundesamt gefördert und von Universität Freiburg, Institut für Geo- und Umweltnaturwissenschaften, Professur für Bodenökologie durchgeführt. Aggregation processes of (organo)mineral associations are assumed to be key processes for the formation and functioning of biogeochemical interfaces in soil. However, a direct link between the forces which induce aggregation and aggregate functioning is still missing. Our hypothesis is that interparticle forces control the diffusion of organic substances within aggregates by shaping the porosity, structure and stability of aggregates. We will analyze aggregates, which we synthesize from different primary particles (goethite, koalinite) using different methods to induce aggregate formation (increase of ionic strength, addition of polyvalent cations, addition of organic polyelectrolytes). Interparticle forces within the aggregates will be calculated based on dynamic light scattering (DLS) and the heat of aggregation (titration calorimetry). The calculations will be validated exemplarily by AFM measurements. In addition we will characterize the porosity, the structure and the stability of the artificial aggregates as well as the particle fraction less than 250 nm of soils and artificial soil materials of the SPP 1315 central experiment. Results will be related to the diffusion of the pollutants into the aggregates, derived from sorption/desorption experiments and nanoSIMS analyses.
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