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.
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.
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.
The simulation models developed in the 1st phase integrate the chemical fate of the veterinary medicines sulfadiazine (SDZ) and difloxacin (DIF) in bulk soil and their subsequent effects on soil microorganisms and on soil functions after single-dose application with manure. In the 2nd project phase, this approach is extended to the rhizosphere, which represents the hotspot of microbial growth in soil and a continuous source of organic compounds released from active roots. The processes of fast and slow sorption, transformation and formation of bound residues of the antibiotics and their main metabolites are adapted to the rhizosphere. The developed effect models for soil functions, structural diversity, and resistance dynamics are extended by relevant plant-soil interactions in close collaboration with the experimental subprojects. The integrated fate-effect model is coupled with a transport model taking heterogeneities of the rhizosphere and plant uptake into account. Processes are parameterized for the two antibiotics SDZ and DIF in rhizosphere and bulk soil with data from the central mesocosm experiment and several planned satellite experiments. The resulting integrated fate-effect models will be evaluated with data from the field experiments. The model is further used to develop indicators such as structural resilience and functional redundancy for antibiotic induced effects, evaluate their applicability for risk assessment and to generate new hypotheses to corroborate the conclusions.
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.
This follow-up project aims to reconstruct natural (climatic) and anthropogenic-induced hydrological changes and to provide new insights on the anthropogenic pollutants emitted in European environment over the last centuries, by focusing on: (1) The largest freshwater lake of Western Europe (Lake Geneva) and especially on industrial (trace metals) and microbial (pathogenic bacterial activity and resistance to antibiotic) pollution in the Vidy Bay; where are discharges the treated wastewaters of Lausanne since 50 years. (2) A drinking reservoir (Lake Brêt) in order to evaluate the impacts of agricultural activities and sewage emissions on the pollution of drinking water in Switzerland over the last century. Results demonstrate a slight enrichment in anthropogenic heavy metal since the 1950s but an additional (agricultural) source of copper during the last decade. In the absence of industries in the catchment, the records of DDT and PCBs highlight the long-range atmospheric transport of POPs that contaminated rural water resources via catchment runoff. (3) Human impact on the deposition of anthropogenic and natural trace element fluxes were measured in sediment cores from Lake Biel and from two upstream lakes (Lake Brienz and Lake Thun), all three connected by the Aare River. Results indicate that that the construction of sediment-trapping reservoirs significantly decreased regional riverine sediment discharge. Radiometric dating of the sediment core from Lake Biel furthermore identified hydrological releases of anthropogenic radionuclides from the nuclear reactor of Mühleberg located at ca.15 km from Lake Biel. Five publications (in refereed journals) directly resulting from this follow-up proposal are in process of publication.
Due to the tendency to bioaccumulate, trace concentrations of selenium in fresh waters have led to disastrous toxicity effects on water birds and fish in the past. Although this adverse impact was first noticed in the early 1980s, to date no sustainable solution has been found for the remediation of selenium contaminated drainage and waste waters. Compared to water soluble forms, elemental selenium is considered less toxic. Therefore, various remediation approaches try to use microorganisms that are highly efficient in reducing selenium oxyanion concentrations by formation of insoluble elemental selenium. Such biogenic elemental selenium, however, does not crystallize to large particles and remains dispersed in solution as a colloidal suspension, thus being subject to re-oxidation, uptake and assimilation by biota. The probable reason for the tendency of biogenic selenium to remain in solution suspended as nanoparticles is an organic polymer layer modifying the surface, preventing crystallization and conferring the selenium core with physico-chemical properties different from particles without such a layer. To date, it is not known, which molecules (proteins, (poly)saccharides, etc.) form this organic polymer layer. Consequently, it is furthermore unknown, if all microbial groups mediating selenium reduction (either via a respiratory or via co-metabolic reduction) produce the same organic polymer layer around the selenium core. The physico-chemical properties of the layer, however, will strongly influence sedimentation and transport processes of selenium in the environment. Due to the complex chemistry and the nanocrystalline character of the selenium particles, uncertainties persist concerning the selenium solid phase, which is formed biogenically. It is not known, if and to which extent selenium that bears such a polymers layer is subject to further biotic and abiotic oxidation and reduction processes, although these processes will largely govern the ecotoxicological effects of selenium. The present project aims at filling the gaps in understanding biogenic selenium formation by systematically investigating the morphology and speciation of the solid phase and the surface modification mechanisms. By direct (spectroscopic) methods we will determine selenium solid phase speciation and its transformations under environmental conditions. We will develop methods allowing the identification of the organic polymer layers modifying selenium nanoparticles by different microbial groups. Thus we will be able to deliver a mechanistic model describing both layer and core of biogenic selenium nanoparticles and the possible impact(s) they have on each other.
Objective: The Integrated Project EURANOS, through the commitment of fifty operational emergency management organisations, 'stakeholder groups' and competent RTD institutes of many European countries who actively contribute to the following objectives, will build a fully interactive framework for initiating and promoting practical improvements of emergency management and rehabilitation strategies in Europe never reached before: (A) creating better communication links between those responsible for nuclear and radiological emergency management in European countries with the perspective of fast notifications, information exchange and interaction through more direct channels; (B) providing better coherence and transparency in decision processes on local, national and border crossing interventions as one input to improving public understanding and acceptance of off-site measures; (C) supporting decisions on effective and timely emergency actions and countermeasures in case of nuclear or radiological emergencies by access to reliable, consistent and comprehensive information, and in this way mitigating radiological and economic consequences; (D) developing a coherent framework for the sustainable rehabilitation of living conditions in contaminated areas by implementing integrated and decentralised approaches involving key stakeholders and the public. A common approach and an European perspective of a more harmonised emergency management and rehabilitation strategy on the local, national and supra-national levels will be created and promoted through common emergency exercises and their thorough evaluation together with all stakeholders involved and through 'stakeholder panels' on the key issues of rehabilitation. The common views on improved technical tools; methods, strategies and guidance will also create initiatives on the administrative and political levels to improve the efficacy of European emergency management and rehabilitation strategies.
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.
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