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.
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.
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.
Arsenic-contaminated ground- and drinking water is a global environmental problem with about 1-2Prozent of the worlds population being affected. The upper drinking water limit for arsenic (10 ìg/L) is often exceeded, especially in Asian countries, such as Vietnam. Household sand filters are already used as one very simple and cost-efficient treatment to remove arsenic from water. Oxidation of dissolved iron (Fe(II)) present in the groundwater leads to the formation of sparsely soluble iron(hydr)oxide particles (Fe(III)OOH) in the sand filter, which bind negatively charged arsenic species and reduce arsenic concentrations in the water. Arsenite (As(III); H3AsO3) binds generally less strong to metal oxides than arsenate (As(V); H2AsO4 -/HAsO4 2-), therefore As(V) is removed much more effectively than As(III). This is why As(III) oxidation to As(V) is of special interest for arsenic removal from drinking water. Whether and how the activity of iron- and arsenite-oxidizing bacteria contributes to effective arsenic removal in household sand filters is currently not known. One of the goals of this study therefore is to isolate, identify, and quantify Fe(II)- and As(III)-oxidizing microorganisms from filters and to study their iron and arsenic redox activities. Cultivation-based work will be complemented by molecular, cultivation-independent techniques to characterize and quantify the microbial communities in samples from different filter locations taken at various time points during filter operation (both at field sites and in artificial laboratory filter systems). The isolated iron- and arsenite-oxidizing bacteria will be studied with respect to their abilities to precipitate iron minerals (in the presence or absence of arsenic) and oxidize arsenite. Biogenic and abiogenic iron minerals formed by the isolated strains in the lab, on the sand filter material in Vietnam and in artificial laboratory filter systems will be identified and characterized, also with respect to arsenic sorption. And we will determine how biotic and abiotic processes that contribute to arsenic mobilization from arsenic-loaded iron mineral phases affect filter performance over time. The long-term goal of this research is to better understand the microbial redox transformation processes that drive arsenic/iron mineral interactions in natural and engineered systems, such as household sand filters and to give recommendations for improved filter use and filter material disposal.
Mercury (Hg) is a persistent micropollutant presenting a substantial risk to the environment and an important threat to the human health. Past and present Hg contaminations of surface waters are thus of major concern due to the potential of Hg to accumulate in biota and magnify in the food chain. Therefore, the improved understanding of the relationship between Hg dispersion, distribution among sediments, particles, colloids and dissolved fractions, as well as accumulation and impact to biota is a prerequisite to fully assess the Hg threat to the aquatic systems and human health. By applying an integrated approach including a combination of field studies, laboratory analyses and numerical simulations, the present proposal aims to assess the impact of the Hg in the industrially impacted surface water bodies in Romania and to identify the possible threat on these resources The project focuses on River Olt basin, as one of the most impacted surface water body in Romania, altered by the cascade dam construction and under extensive past and present industrial activity. The Rm Valcea region comprises a high number of industrial companies including a large chlor-alkali plant (Oltchim), which is recognized as important point sources of Hg. A large array of hydro(geo)logical, physical, chemical, and ecotoxicological tools will be used to address the following key issues: - Performance of Hg survey and estimation the pollution extent in water and sediments; - Determination of the transport and dispersion of Hg in water column and sediments; - Improvement of the understanding on the behaviour of Hg associated to colloids, inorganic particles and organic matter; - Assessment of the bioaccumulation and effect of Hg to different organisms with emphasis on the primary producers in particular microalgae and macrophytes; - Evaluation of the food chain transfer and possible risks for the human health. The project will largely contribute to the understanding of mercury fate and impact in the contaminated systems and improved knowledge on complex processes governing the transfer and impact of Hg from the contaminated surface waters to humans. The project is also expected to contribute broadly to solving societal problems in Romania and to provide a scientific base for a sound definition of the existing problem and understand the causal chain, as well as it will help to develop efficient and cost-effective measures for protection. Strengthening the capacity, improving integration of scientists in the international network as well as developing 'best practices' for impact assessment of pollutants are other major outcomes of the project. They will be a significant step forward contaminant assessment in the entire Danube - Black Sea - Caspian Sea region, as it is a commonly accepted that historical industrial pollution from former communist times represents a significant threat for public health.
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