Chromium (Cr) is introduced into the environment by several anthropogenic activities. A striking ex-ample is the area around Kanpur in the Indian state of Uttar Pradesh, where large amounts of Cr-containing wastes have been recently illegally deposited. Hexavalent Cr, a highly toxic and mobile contaminant, is present in significant amounts in these wastes, severely affecting the quality of sur-roundings soils, sediments, and ground waters. The first major goal of this study is to clarify the solid phase speciation of Cr in these wastes and to examine its leaching behavior. X-ray diffraction and synchrotron-based X-ray absorption spectroscopy techniques will be employed for quantitative solid phase speciation of Cr. Its leaching behavior will be studied in column experiments performed at un-saturated moisture conditions with flow interruptions simulating monsoon rain events. Combined with geochemical modeling, the results will allow the evaluation of the leaching potential and release kinetics of Cr from the waste materials. The second major goal is to investigate the spatial distribution, speciation, and solubility of Cr in the rooting zone of chromate-contaminated soils surrounding the landfills, and to study the suitability of biochar as novel soil amendment for mitigating the deleterious effects of chromate pollution. Detailed field samplings and laboratory soil incubation studies will be carried out with two agricultural soils and biochar from the Kanpur region.
In soils and sediments there is a strong coupling between local biogeochemical processes and the distribution of water, electron acceptors, acids, nutrients and pollutants. Both sides are closely related and affect each other from small scale to larger scale. Soil structures such as aggregates, roots, layers, macropores and wettability differences occurring in natural soils enhance the patchiness of these distributions. At the same time the spatial distribution and temporal dynamics of these important parameters is difficult to access. By applying non-destructive measurements it is possible to overcome these limitations. Our non-invasive fluorescence imaging technique can directly quantity distribution and changes of oxygen and pH. Similarly, the water content distribution can be visualized in situ also by optical imaging, but more precisely by neutron radiography. By applying a combined approach we will clarify the formation and architecture of interfaces induces by oxygen consumption, pH changes and water distribution. We will map and model the effects of microbial and plant root respiration for restricted oxygen supply due to locally high water saturation, in natural as well as artificial soils. Further aspects will be biologically induced pH changes, influence on fate of chemicals, and oxygen delivery from trapped gas phase.
Agriculture is the major contributor of nitrogen to ecosystems, both by organic and inorganic fertilizers. Percolation of nitrate to groundwater and further transport to surface waters is assumed to be one of the major pathways in the fate of this nitrogen. The quantification of groundwater and associated nitrate flux to streams is still challenging. In particular because we lack understanding of the spatial distribution and temporal variability of groundwater and associated NO3- fluxes. In this preliminary study we will focus on the identification and quantification of groundwater and associated nitrate fluxes by combining high resolution distributed fiber-optic temperature sensing (DTS) with in situ UV photometry (ProPS). DTS is a new technique that is capable to measure temperature over distances of km with a spatial resolution of ca1 m and an accuracy of 0.01 K. It has been applied successfully to identify and quantify sources of groundwater discharge to streams. ProPS is a submersible UV process photometer, which uses high precision spectral analyses to provide single substance concentrations, in our case NO3-, at minute intervals and a detection limit of less than 0.05 mg l-1 (ca.0.01 mg NO3--Nl-1). We will conduct field experiments using artificial point sources of lateral inflow to test DTS and ProPS based quantification approaches and estimate their uncertainty. The selected study area is the Schwingbach catchment in Hessen, Germany, which has a good monitoring infrastructure. Preliminary research on hydrological fluxes and field observations indicate that the catchment favors the intended study.
In structured soils, the interaction of percolating water and reactive solutes with the soil matrix is mostly restricted to the surfaces of preferential flow paths. Flow paths, i.e., macropores, are formed by worm burrows, decayed root channels, cracks, and inter-aggregate spaces. While biopores are covered by earthworm casts and mucilage or by root residues, aggregates and cracks are often coated by soil organic matter (SOM), oxides, and clay minerals especially in the clay illuviation horizons of Luvisols. The SOM as well as the clay mineral composition and concentration strongly determine the wettability and sorption capacity of the coatings and thus control water and solute movement as well as the mass exchange between the preferential flow paths and the soil matrix. The objective of this proposal is the quantitative description of the small-scale distribution of physicochemical properties of intact structural surfaces and flow path surfaces and of their distribution in the soil volume. Samples of Bt horizons of Luvisols from Loess will be compared with those from glacial till. At intact structural surfaces prepared from soil clods, the spatial distribution (mm-scale) of SOM and clay mineral composition will be characterized with DRIFT (Diffuse reflectance infrared Fourier transform) spectroscopy using a self-developed mapping technique. For samples manually separated from coated surfaces and biopore walls, the contents of organic carbon (Corg) and the cation exchange capacity (CEC) will be analyzed and related to the intensities of specific signals in DRIFT spectra using Partial Least Square Regression (PLSR) analysis. The signal intensities of the DRIFT mapping spectra will be used to quantify the spatial distribution of Corg and CEC at these structural surfaces. The DRIFT mapping data will also be used for qualitatively characterizing the small scale distribution of the recalcitrance, humification, and microbial activity of the SOM from structural surfaces. The clay mineral composition of defined surface regions will be characterized by combining DRIFT spectroscopic with X-ray diffractometric analysis of manually separated samples. Subsequently, the spatial distribution of the clay mineral composition at structural surfaces will be determined from the intensities of clay mineral-specific signals in the DRIFT mapping spectra and exemplarily compared to scanning electron microscopic and infrared microscopic analysis of thin sections and thin polished micro-sections. The three-dimensional spatial distribution of the total structural surfaces in the volume of the Bt horizons will be quantified using X-ray computed tomography (CT) analysis of soil cores. The active preferential flow paths will be visualized and quantified by field tracer experiments. These CT and tracer data will be used to transfer the properties of the structural surfaces characterized by DRIFT mapping onto the active preferential flow paths in the Bt horizons.
In freshwater sediments, iron oxidation is dominated by phototrophic and chemotrophic (aerobic and nitrate-reducing) Fe(ll)-oxidizing microorganisms. Although these biogeochemical processes have been investigated in detail in laboratory studies, not much is known about their spatial distribution, interactions (e.g. competition) amongst each other, as well as their response towards environmental perturbations (i.e. temperature, geochemical variations (nutrient, organic matter input)). This research proposal aims to investigate the activity, abundance and resource competition between different chemotrophic (aerobic and (autotrophic/mixotrophic) anaerobic nitrate-reducing) and phototrophic ironoxidizing microorganisms. In order to better understand the spatial distribution of nitrate-reducing iron oxidizing bacteria, microbial nitrate-producing and competing, nitrate-depletion processes will also be studied throughout the sedimentary redox gradient. In addition, the activity and abundance of the ironoxidizing processes will be quantified with (geo)microbiological, molecular and novel spectral imaging techniques. Using high resolution geochemical measurements (microsensors) we will characterize the environmental conditions these bacteria experience in order to determine the role of spatial and functional niche competition in microbial iron oxidation and the interconnection to the N-cycle. Iron mineral formation will be investigated as a function of the microbial spatial and temporal activity, depending on environmental perturbations. The proposed research study will strongly improve the understanding of iron cycling, the interconnection to the N-cycle, as well as interactions and competition between phototrophic and chemotrophic metabolisms in aquatic environments.
The broad objective of the research is to gain a fundamental understanding of the surface reaction chemistry of exhaust catalysts operating under cycling conditions. Using an integrated theoretical approach we specifically target NOx abatement, with particular emphasis on the appearance and destruction of surface oxide phases as the reactor conditions cycle from oxidative to reductive during the operation of the NOx Storage Reduction (NSR) catalyst system. Methodologically this requires material-specific, quantitative and explicitly time-dependent simulation tools that can follow the evolution of the system over the macroscopic time-scales of NSR cycles, while simultaneously accounting for the atomic-scale site heterogeneity and spatial distributions at the evolving surface. To meet these challenging demands we will develop a novel multi-scale methodology relying on a multi-lattice first-principles kinetic Monte Carlo (kMC) approach. As representative example the simulations will be carried out on a PdO(101)/Pd(100) surface oxide model, but care will be taken to ensure a generalization of the multi-lattice first-principles kMC approach to other systems in which phase transformations may occur and result in a change in the surface lattice structure depending upon environmental variables.
The overall goal of this project is to provide a systematic assessment of the feasibility of applying the virtual water concept to improve water productivity in individual provinces and for the whole country in Iran, taking into account various natural, socio-economic and resources constraints. Specific objectives relating to the overall goal include: 1 To assess the water resources availability and reliability in different regions/provinces taking into consideration the fluctuation within a year and between years. 2 To estimate the water requirement of different crops in different regions/provinces with improved spatial resolution. 3 To estimate crop water productivities with respect to quantity and value of product on irrigated and rain-fed land concerning consumptive water use and water supply in different regions/provinces. 4 To assess the water use intensity in different regions/provinces based on the water resources availability and water demand in the industrial, domestic and agricultural sectors at present and in the next 10-20 years. 5 To provide scenarios for improving regional/provincial and national water productivity through regional crop structural adjustment and inter-provincial food trade, taking into account natural, socio-economic and resources constraints at different levels and other regional and national objectives. Water resources endowment in Iran is generally poor and the spatial distribution is uneven. Some regions are enduring severe water stress. Producing more food with increasing water scarcity is a daunting challenge to the country. In this project, water resources availability and crop water requirement across provinces/regions in Iran will be estimated to lay the basis for the assessment. Water productivity across regions will be evaluated with respect to physical yield and value of products and different expressions of water input. Scenarios for improving water productivity through regional crop structural adjustment and virtual water trade are proposed for individual regions and then aggregated to the whole country, taking into consideration constraints concerning natural and socio-economic conditions and other regional and national objectives. The SWAT model (Soil and Water Assessment Tool) will be used for the assessment of water resources availability and crop water requirement in different provinces/regions. The SWAT model is currently used in several other projects at Eawag. The regional socio-economic data and farmers' water use behavior will be sought from both secondary data and field surveys and interviews. Scenarios for regional crop structural adjustment and virtual water trade will be proposed based on optimizing water productivity subject to various constraints.
The Okavango is a large African wetland of prime ecological importance. Its existence is in jeopardy due to upstream development and increasing water demand in combination with predicted climatic change. Less water means a reduction of the permanent and seasonal swamp areas. The project creates a computer model serving as a tool to predict the impact of upstream hydraulic measures, channel management and changes in climate on the availability of water in the delta and its spatial distribution. It also looks at the sediment transport. The availability of water e.g. expressed by the frequency of flooding at a location is essential for the type of habitat prevailing at that point. Changes of water availability will therefore also cause changes in the habitat composition of the delta. Management of channels by cutting of papyrus or dredging will change the distribution of flooded areas. The interaction of the channels of the Okavango Delta with the floodplains and the underlying groundwater is of crucial importance. Vegetation on the islands gets its water through infiltration from the river channels and the yearly flood propagates both in the channels and in the groundwater. Therefore the model couples the surface water flow - in channels and overland during flooding - with the groundwater flow. In a region with little infrastructure it is hard to find data for this modelling effort. However, nowadays many data can be found through remote sensing techniques both from satellite and airborne platforms. These include the topography (from the Shuttle Mission), the rainfall (from METOESAT 5), the evapotranspiration (from NOAA-AVHRR) and the extension of water surfaces in their temporal development (from radar satellites and others). The thickness of the groundwater body is evaluated from aeromagnetic records provided by the geological Survey of Botswana. The infiltration zones can be seen through another airborne geophysical technique, the TEM-method. This survey is financed by the Botswanan government and will take place in April 2007. All satellite and airborne information needs calibration and interpretation through ground truth which is obtained in yearly field campaigns. The water areas serve as data for the adjustment and verification of the model. The insight gained through the model will flow into the work of the Okavango River Commission (OKACOM) which has to negotiate the permissible water use in the upstream.
Die raeumliche Verteilung der Boden-Macrofauna zweier Laubwaldbestaende soll mit geostatistischen Methoden analysiert und mit abiotischen Variablen, der Vegetationsstruktur und der Aktivitaet von Bodenenzymen parallelisiert werden. Wichtige Tiergruppen: Regenwuermer, Asseln, raeuberische Tausendfuessler.
In pedology, soilscapes are characterised by a typical spatial and taxonomic relation between the soils, as well as by the relation between the soils and other landform and landscape characteristics. These landscape characteristics as driving forces for soil formation show local, regional and supra-regional components. It is therefore important to gather and incorporate information about the soil forming factors not only from a specific sampling point, but also from its larger spatial surroundings for reasonable descriptions of the complex soil-landscape relations. Therefore, multi- or hyper-scale approaches are required, which however, are rarely reported in literature. Moreover, most studies are lacking any interpretations and concepts for the description of soil formation, although these are most crucial for describing and understanding the complex environmental processes and interactions of landscapes and soils.The aim of this project is to develop a new hyper-scale mapping approach as well as a new theoretical concept for its pedologic interpretation. Under the overarching goal of a new spatially contextualized soil formation theory the objective of the project is to achieve more holistic descriptions of soil and environmental formation but also the optimization of spatial prediction models for estimating soil properties functions and threats. This is urgently needed in order to meet the increasing global demand for accurate and high-resolution soil information to estimate and handle the impacts of global climate change, population growth, food security, and bio energy.The framework, which will be developed, applied, tested and validated for several landscapes around the world in this project, focuses on determining the influence of local, regional and supra-regional landscape surface shape on soil formation in terms of hyper-scale digital terrain analysis and tries to reveal the interactions of relief with other environmental covariates on different spatial scales. The objectives are (i) to develop a new hyper-scale terrain analysis method, (ii) to apply, develop and/or adapt specific data analysis and data mining approaches to derive the information required for pedological interpretations and as an integrative part (iii) to develop a new theoretical framework for soil formation analysis. This will provide a) information on the specific influence of local to supra-regional parts of environmental covariates on soil formation, b) approaches to visualize the geomorphic systems interacting with other covariates and jointly influence soil formation, c) approaches to derive information on the interactions between different geomorphic features and scales, as well as d) information on the complex interactions between geomorphic and other environmental covariates at different scales to derive better knowledge about the spatial distribution as well as the genesis of one of our most important environmental resources - soil.
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