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Found 36 results.

Effect of diffusive/dispersive processes on stable isotope ratios of organic contaminants in aquifer systems

Groundwater contamination by organic compounds represents a widespread environmental problem. The heterogeneity of geological formations and the complexity of physical and biogeochemical subsurface processes, often hamper a quantitative characterization of contaminated aquifers. Compound specific stable isotope analysis (CSIA) has emerged as a novel approach to investigate contaminant transformation and to relate contaminant sources to downgradient contamination. This method generally assumes that only (bio)chemical transformations are associated with isotope effects. However, recent studies have revealed isotope fractionation of organic contaminants by physical processes, therefore pointing to the need of further research to determine the influence of both transport and reactive processes on the observed overall isotope fractionation. While the effect of gasphase diffusion on isotope ratios has been studied in detail, possible effects of aqueous phase diffusion and dispersion have received little attention so far.The goals of this study are to quantify carbon (13C/12C) and, for chlorinated compounds, chlorine (37Cl/35Cl) isotope fractionation during diffusive/dispersive transport of organic contaminants in groundwater and to determine its consequences for source allocation and assessment of reactive processes using isotopes. The proposed research is based on the combination of high-resolution experimental studies, both at the laboratory (i.e. zero-, one- and two-dimensional systems) and at the field scales, and solute transport modeling. The project combines the expertise in the field of contaminant transport with the expertise on isotope methods in contaminant hydrogeology.

Immobilisation of arsenic in paddy soil by iron(II)-oxidizing bacteria

Arsenic-contaminated ground- and drinking water is a global environmental problem with about 1-2Prozent of the world's population being affected. The upper drinking water limit for arsenic (10 Micro g/l) recommended by the WHO is often exceeded, even in industrial nations in Europe and the USA. Chronic intake of arsenic causes severe health problems like skin diseases (e.g. blackfoot disease) and cancer. In addition to drinking water, seafood and rice are the main reservoirs for arsenic uptake. Arsenic is oftentimes of geogenic origin and in the environment it is mainly bound to iron(III) minerals. Iron(III)-reducing bacteria are able to dissolve these iron minerals and therefore release the arsenic to the environment. In turn, iron(II)-oxidizing bacteria have the potential to co-precipitate or sorb arsenic during iron(II)- oxidation at neutral pH followed by iron(III) mineral precipitation. This process may reduce arsenic concentrations in the environment drastically, lowering the potential risk for humans dramatically.The main goal of this study therefore is to quantify, identify and isolate anaerobic and aerobic Fe(II)-oxidizing microorganisms in arsenic-containing paddy soil. The co-precipitation and thus removal of arsenic by iron mineral producing bacteria will be determined in batch and microcosm experiments. Finally the influence of rhizosphere redox status on microbial Fe oxidation and arsenic uptake into rice plants will be evaluated in microcosm experiments. The long-term goal of this research is to better understand arsenic-co-precipitation and thus arsenic-immobilization by iron(II)-oxidizing bacteria in rice paddy soil. Potentially these results can lead to an improvement of living conditions in affected countries, e.g. in China or Bangladesh.

Handling of radium and uranium contaminated waste piles and other wastes from phosphate ore processing

Depletion of algal toxin-contaminated water using selective biofilters based on plant-produced antibodies (plantibodies)

Although the use of genetically modified plants for bioremediation, or the in situ cleaning of contaminated sites, has been known for quite some time, little attention has so far been paid to the production of antibodies in plants and their ex vivo application in selective depletion. Therefore, highly affine and specific antibodies against algal toxins using microcystin as an example will be produced in plants at low cost within this research project. The basis is a monoclonal antibody (Mab 10E7, species: mouse) generated in a former research project. The sequence of the variable domains will be determined, optimized for plants and sub cloned into suitable plant transformation vectors, which already contain constant antibody sequences. In addition, a scFv fragment containing different tag sequences and fusion proteins will be constructed. Leaf-based (tobacco) as well as seed-based (barley) systems will be used.Affinity-purified plant-produced antibodies (plantibodies) will be characterized in detail for their binding properties using microtitre plate-ELISA and surface plasmon resonance (SPR). The monoclonal mouse antibody will be used as reference. To assure cost-efficiency for future applications, roughly purified fractions (sequential pH and temperature treatment followed by filtration) will be tested for the upscaling. Following immobilization of the plantibody fractions on suitable substrates, for instance membranes, porous polymer monoliths or in porous glasses, their application for depletion will be defined using model water samples spiked fortified with microcystins.

Antimony leaching from contaminated soil under different water regimes

Antimony (Sb) is a rather rare element in the earth's crust, but in the recent past, human activities have led to highly elevated Sb concentrations in soils and sediments at many locations and, as a consequence, to increased exposure of biota to this toxic element. Soil contamination by Sb has recently become an urgent issue in particular on shooting ranges. In Switzerland, all shooting ranges are currently examined and will be remediated within the next decade. This implies the removal of large quantities of contaminated soil. Large fractions of these soils are not heavily contaminated but have to be treated because they are located in pollution-sensitive areas such as groundwater protection zones. This soil can potentially be reused for less sensitive types of land-use, saving high treatment costs and precious hazardous waste disposal space. Knowledge about the risks of Sb leaching from such soils is very limited, however. One key factor regarding solute leaching is the water regime, particularly in soils subject to permanent or periodic water-logging. Water-logging strongly inhibits soil aeration, and this can have a strong influence on the entirety of chemical and biological conditions affecting solute transport in soil. This holds all the more for elements that are sensitive to changes in their oxidation state under environmental conditions such as Sb. Given that there is very little information available on the transport behavior of Sb in soils, particularly under dynamic water regimes, this project has the aim to investigate the influence of water-logging on Sb leaching from contaminated soil. For this purpose, we carry out experiments with a relocated shooting range soil as well as with a comparable synthetic soil in order to identify and model the role of sorption and redox processes on Sb mobilization and leaching. Special attention will be given to the speciation of Sb in the soil solution. The results will be relevant beyond providing a scientific basis for the risk assessment of Sb leaching from contaminated soil, as it will also further the mechanistic understanding of how water-logging affects the transport of redox-sensitive solutes in soils in general.

Physical and chemical processes that lead to virus inactivation at solid-water interfaces - a combined computational and experimental approach

Virus inactivation processes at water-solid interfaces are key factors determining the persistence of viruses in various aqueous environments. These include environmental systems such as surface and groundwater, various food products, and blood and other bodily fluids. Once released into a body of water, viruses rapidly associate with water-solid interfaces. Interactions with solid surfaces influence virus disinfection, and thus determine the spread and persistence of infective viruses. Despite the importance of interfacial disinfection processes, their underlying causes remain poorly understood. In this sinergia project, we will identify the most important processes contributing to virus inactivation at interfaces, and we will develop a comprehensive model of the virus characteristics and surface properties that influence inactivation behavior. Our investigations will focus on model systems representative of one of the great challenges to public health, namely water resources contaminated by viral pathogens. To obtain a system characterization at the molecular level, we will use a combined computational and experimental approach. This project is divided into three sub-projects: sub-project A will establish the computational framework that simulates the physical-chemical interactions of virus with the water-solid interface; sub-project B will experimentally evaluate the extent and relative importance of physical and chemical processes that lead to virus inactivation; sub-project C will be dedicated to characterizing the microscale distribution of oxidizing chemical species at the solid-water interfaces. The combination of theory and experiment is well suited to overcome the challenges associated with the complex virus-interface system, and to derive a generally valid concept of virus inactivation at solid-water interfaces.

Aquabase, Einfluss der Klärschlamm Prozessierung auf das Schicksal von Nonylphenol in klärschlammbehandelten Böden

Lipophile endokrin wirksame Chemikalien, z.B. synthetische Kontrazeptiva, reichern sich im bei der Abwasserbehandlung entstehenden Klärschlamm an. Wird dieser Klärschlamm als Dünger landwirtschaftlich genutzter Flächen verwendet, besteht die Gefahr, dass die Fremdstoffe aus dem Boden durch Run-off ausgetragen oder von Pflanzen aufgenommen wird. Aufgrund der verschiedenen Aufarbeitungsschritte des Klärschlamms - Stabilisierung, Konditionierung, Entwässerung, Entpathogenisierung - entstehen Klärschlämme, die sich in ihren physikochemischen Eigenschaften (Mineralgehalt, pH, Fein- und Grobstruktur) und in ihrem Gehalt an Kontaminanten unterscheiden können. Bei der Verwendung dieser Schlämme als Dünger können sich die darin enthaltenen Kontaminanten bezüglich ihres Abbau- und Transpoirtverhaltens sowie der Bioverfügbarkeit unterschiedlich verhalten. In diesem Projekt wird das Umweltverhalten ausgewählter Umweltchemikalien in Klärschlämmen in Abhängigkeit von deren Prozessierung und Aufarbeitung untersucht.

Establishing of improved cultivars of high yielding food crops by means of conventional in vitro-breeding, mutagenesis and selection techniques (non-GMO)

In previous projects of the EC and Switzerland a non-GMO approach of conventional in-vitro breeding and mutagenesis was used to introduce a good number of new genotype of crop plants with significantly enhanced properties for metal accumulation, extraction and exclusion, for improving of the effieciency of phytoextraction technique for cleaning of contaminated soil. Within COST Action 859 most efficient genotypes of sunflower, Brassica and tobacco and specific cultivation methods will carefully be assessed and comparative field experiments in Switzerland and Belgium will be continued with the aim to optimise and validate the 'improved phytoextraction technique' and to bring this sustainable remediation procedure towards a practical use.

Untersuchungen zur biologischen Funktion des Mykotoxins Zearalenon

Zearalenon ist ein nichtsteroides Mykotoxin mit östrogener Wirkung, das vorwiegend vom pflanzenpathogenen Pilzen wie Fusarium graminearum (Gibberella zea) und Fusarium culmorum gebildet wird. Infolge der von diesen Pilzen hervorgerufenen Krankeiten von wichtigen Kulturpflanzen, wie z.B. Ährenfusariose von Weizen und Kolbenfäule von Mais, kann es zur Kontamination von Lebensmitteln und Futtermitteln mit gesundheitsrelevanten Mengen des Mykotoxins kommen. Gegenwärtig ist völlig ungeklärt, ob die Fähigkeit zur Produktion von Zearalenon die Fähigkeit des Pilzes beeinflußt, als Pflanzenpathogen zu wirken. Es ist auch unbekannt, ob Zearalenon imstande ist, in bestimmte pflanzenphysiologische Vorgänge einzugreifen und es dadurch dem Pilz erleichtert, die Pflanze zu kolonisieren. Im Rahmen dieser Arbeit soll versucht werden, Voraussetzungen zur Beantwortung dieser Fragen zu schaffen: Durch die Einbringung des Reportergens GFP (Green Fluorescent Protein) in den pflanzenpathogenen Pilz Fusarium culmorum sollte es möglich werden, den Infektionsprozeß zu verfolgen und die Rolle von Zearalenon zu untersuchen. Durch Etablierung der REMI-Methode (Restriction Enzyme Mediated Integration) soll die Grundlage geschaffen werden, Insertionsmutanten von F. culmorum zu identifizieren, die nicht mehr imstande sind das Mykotoxin Zearalenon zu bilden.

Steady-State Dilution and Mixing-Controlled Reactions in Three-Dimensional Heterogeneous Porous

Understanding transport of contaminants is fundamental for the management of groundwater re-sources and the implementation of remedial strategies. In particular, mixing processes in saturated porous media play a pivotal role in determining the fate and transport of chemicals released in the subsurface. In fact, many abiotic and biological reactions in contaminated aquifers are limited by the availability of reaction partners. Under steady-state flow and transport conditions, dissolved reactants come into contact only through transverse mixing. In homogeneous porous media, transverse mixing is determined by diffusion and pore-scale dispersion, while in heterogeneous formations these local mixing processes are enhanced. Recent studies investigated the enhancement of transverse mixing due to the presence of heterogeneities in two-dimensional systems. Here, mixing enhancement can solely be attributed to flow focusing within high-permeability inclusions. In the proposed work, we will investigate mixing processes in three dimensions using high-resolution laboratory bench-scale experiments and advanced modeling techniques. The objective of the proposed research is to quantitatively assess how 3-D heterogeneity and anisotropy of hydraulic conductivity affect mixing processes via (i) flow focusing and de-focusing, (ii) increase of the plume surface, (iii) twisting and intertwining of streamlines and (iv) compound-specific diffusive/dispersive properties of the solute species undergoing transport. The results of the experimental and modeling investigation will allow us to identify effective large-scale parameters useful for a correct description of conservative and reactive mixing at field scales allowing to explain discrepancies between field observations, bench-scale experiments and current stochastic theory.

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