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.
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.
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.
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.
Im Rahmen dieses Projektes wurde die Situation von Reststoffen aus der Papierindustrie europaweit durch eine umfangreiche Datenaufnahme abgeschätzt. Hierbei zeigte sich, dass in Frankreich und Deutschland die größten Mengen an Papierreststoffen entstehen und die Entsorgungsvarainten am vielfältigsten sind. In den anderen europäischen Ländern fallen wesentlich weniger Reststoffe an, zu meist durch das Fehlen einer Abwasserreinigungsanlage oder durch eine niedrige Altpapiereinsatzquote. Die Reststoffe aus diesen Ländern werden überwiegend auf einer Deponie entsorgt. In einem weiteren Teil des Projektes wurde die stoffliche Verwertung durch Kompostierung von Papierreststoffen auf biochemische und mikrobiologische Parameter hin untersucht. Dabei wurde auch der potenzielle Abbau von chlorierten Phenolen betrachtet. Es zeigte sich, dass die chlorierten Phenole keine große Belastung für Papierreststoffe darstellen. Da im Gegensatz zu den chlorierten Phenolen die Menge an chlorierten organischen Substanzen (AOX) in Papierreststoffen sehr hoch ist, wurde das umweltchemische Verhalten von AOX-Substanzen durch Schüttelversuche in verschiedenen Lösungsmitteln und Lysimeterversuchen getestet. Die Ergebnisse zeigen, dass AOX-Substanzen sich nur in geringem Umfang durch eine Elution mit wässrigen Medien lösen lassen. Da die organischen Schadstoffe (gemessen als AOX) in Papierreststoffen besonders relevant sind, sollte versucht werden, mehr über die chemische Struktur (insbesondere das Molekulargewicht) dieser Substanzen herauszufinden. Dabei wurden die Methoden der Ultrafiltration und der Gelpermeationschromatographie eingesetzt. Die Ergebnisse zeigen eine hohen Anteil AOX-Substanzen im hochmolekularen Bereich, wobei die Struktur der Verbindungen stark vom anfallenden Reststofftyp abhängt. So konnte nachgeweisen werden, dass der Haupteil an AOX-Substanzen in den Deinkingreststoffen überwiegend aus chlorierten Druckfarben, insbesondere den gelben Pigmenten, besteht. Eine Substitution dieser Farbstoffe aus der Azofarbgruppe würde zu einer deutlichen Reduktion der AOX-Problematik führen.
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.
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