Water security is now widely recognised as a strategic issue which will place limits upon South Africa’s possible economic and developmental futures. Although a country with a large surface area and reasonable average rainfall, the amount of available water is small due to the extremely high average evaporation. In combination with a rapid growth in population and increase in industrial water usage, South Africa is becoming a country of water stress (AEON, 2010). Besides water quantity, the second major challenge includes water quality. It was understood that due to a broad range of reasons, wastewater treatment plants are often not functioning properly. Furthermore, some regulations may not be strict enough yet (e.g. Phosphate ban) or may be not fully implemented and enforced. This leads to eutrophication of lakes and compromised downstream river water quality. In the third place, the groundwater situation is precarious, both with respect to quantity and with respect to quantity. In some places groundwater tables are decreasing, due to unsustainable groundwater harvesting (e.g., agriculture). In other places, groundwater tables are rising due to increased infiltration and stopped mining activities. Also the groundwater quality problems are very diverse: they range from the acid groundwater in mining areas to problems with groundwater depletion in intensively irrigation. In order to gain deeper insight in to the water issue in South Africa and identify potential areas of collaboration between Switzerland and the host country, a five day fact finding mission was organized. This report focuses on the results of a fact finding mission. It describes the possible projects arising from such mission; projects which are aimed at stimulating cooperation between Switzerland and South Africa on issues related to the improvement of security and management of water resources in South Africa. The subject areas of the projects are strongly aligned with South African priorities such as: drinking water issues in rural settings; mitigation of eutrophication of water reservoirs; capacity building and capacity retention; improvement of water quality by source pollutant control; prevention of acid mine drainage and sustainable use of deserted mines. The proposed project on drinking water could provide an important contribution in reaching the Millenium Development Goals with regard to providing access to safe drinking water to all. In order to initiate such a collaborative program, a project outline is proposed which includes Swiss seed money, which will be used to define projects in more detail, identify partners and identify complementary R&D resources from South Africa agencies.

Die Nase (Chondrostoma nasus) war vor der Industrialisierung die häufigste Fischart in der Äschenund Barbenregion der Schweizer Fliessgewässer. Die Nasenbestände sind in den letzten hundert und insbesondere in den letzten 20-30 Jahren jedoch schweizweit dramatisch zusammengebrochen (Maie et al., 1995). Lokal sind viele Populationen vollständig ausgestorben. Eindeutige Ursachen für diesen Rückgang konnten bisher nicht ermittelt werden. Die Anforderung der Nase an Habitatvielfalt und Vernetzung der Fliessgewässer, gekoppelt mit der massiven Verbauung und Fragmentierung sowie der Beeinflussung des Temperatur- und Abflussregimes durch Kraftwerke der Mittellandgewässer scheinen aber die Hauptursachen zu sein. Nebst dem Bedürfnis nach gewässerbaulichen Massnahmen steigt der politische Druck, Nase durch gezielten Besatz in den gefährdeten und zukünftig renaturierten Regionen zu stützen oder wieder einzuführen. Weil der Besatz einen nicht zu unterschätzenden Eingriff in natürliche Prozesse wie natürliche Selektion und Partnerwahl darstellt, welche die lokale Anpassung an Umweltbedingungen fördern, wurde die EAWAG vom BAFU beauftragt, eine populationsgenetische Studie der Nasenpopulationen in der Schweiz durchzuführen. Diese Studie soll klären, ob es in der Schweiz genetisch differenzierte Populationen gibt und ob sich diese spezifisch an ihre Umwelt angepasst haben.

Die Nase war vor der Industrialisierung die häufigste Fischart in der Äschen- und Barbenregion der Schweizer Fliessgewässer. Die Nasenbestände sind in den letzten hundert und insbesondere in den letzten 20-30 Jahren jedoch schweizweit dramatisch zusammengebrochen (Maier et al., 1995). Lokal sind viele Populationen vollständig ausgestorben (Abb. 3). Eindeutige Ursachen für diesen Rückgang konnten bisher nicht ermittelt werden. Die Anforderung der Nase an Habitatvielfalt und Vernetzung der Fliessgewässer, gekoppelt mit der massiven Verbauung und Fragmentierung sowie der Beeinflussung des Temperatur- und Abflussregimes durch Kraftwerke der Mittellandgewässer scheinen aber die Hauptursachen zu sein. Neben dem Bedürfnis nach gewässerbaulichen Massnahmen steigt der politische Druck, Nasen durch gezielten Besatz in den gefährdeten und zukünftig renaturierten Regionen zu stützen oder wieder einzuführen. Weil der Besatz einen nicht zu unterschätzenden Eingriff in natürliche Prozesse wie natürliche Selektion und Partnerwahl darstellt, welche die lokale Anpassung an Umweltbedingungen fördern, wurde die EAWAG vom BAFU beauftragt, eine populationsgenetische Studie der Nasenpopulationen in der Schweiz durchzuführen. Diese Studie soll klären, ob es in der Schweiz genetisch differenzierte Populationen gibt und ob sich diese spezifisch an ihre Umwelt angepasst haben.

Background In Switzerland the assessment of surface water quality with respect to contaminations by plant protection products (PPP) is based on the Swiss water protection law (Schweizer Bundesgesetz vom 24. Januar 1991 über den Schutz der Gewässer, Gewässerschutzgesetz, GSchG, SR 814.20), as well as on the Swiss water protection ordinance (Gewässerschutzverordnung vom 28. Oktober 1998, GSchV, SR 814.201). According to GSchV a general quality criterion of 0.1 μg/l exists for single organic pesticides (plant protection products and biocidal products) in Swiss running waters. Other values remain subject to reserve on the basis of individual substance assessments in the context of the authorisation procedure. In the European Union, the protection of water bodies is regulated under the Water Framework Directive (2000/60/EC, WFD). In addition, the aquatic risk of PPP is already being assessed during the PPP authorisation procedure under the ordinance on the placing of plant protection products on the Swiss market (Verordnung vom 18. Mai 2005 über das Inverkehrbringen von Pflanzenschutzmitteln, Pflanzenschutzmittelverordnung, PSMV, SR 916.161) and in the EU under the Council Directive 91/414/EEC of 15 July 1991 concerning the placing of plant protection products on the market. Aims and Approaches The goal of this project was to propose an appropriate method for the derivation of Environmental Quality Standards (EQS) for active substances (AS) from PPP in Swiss surface waters, consistent with the aims of the Swiss legislation on water protection (GSchG and GSchV). For this purpose the approaches currently applied in the EU were (i) identified by query and review, (ii) reviewed with regard to their underlying protection goals and methods and (iii) applied in case studies to six AS currently used in PPPs in Switzerland: the herbicides Diuron, Mecoprop and Terbuthylazine, the fungicide Carbendazim and the insecticides Diazinon and Imidacloprid. The resulting EQS values were compared with EQS values derived for the same AS by other authorities as well as with the regulatory acceptable concentrations (RACs) that can be calculated from the PPP authorisation documents. Results The review demonstrated that minor differences exist between the ecotoxicological protection goals underlying the three guidance documents currently used for deriving EQS under the Water Framework Directive (WFD), the draft Technical Guidance Document for EQS (TGD for EQS), its predecessor („Lepper method“) and the Dutch guidance document for the implementation of the WFD, and those described in the Swiss water protection law (GSchG) and in the Swiss Water Protection Ordinance (GSchV). With some additional provisions concerning the data selection however, the approaches of the WFD are compatible with the GSchG, therefore the selection of relevant toxicity data should be guided not only by their relevance under the WFD but also by the protection goals from the GSchG and the GSchV. A review of the methods showed that the three approaches are very similar. The few minor distinctions, led to small differences regarding the EQS values derived in the case studies for the selected AS. However, EQS values never differed by more than a factor of 3, if the use of different data sets and/or different “expert judgement“ in the evaluation of data could be ruled out. The influence of this - so called - “expert judgement” on resulting EQS values was significant, mostly due to differences in weighting the available data and/or the selection of the assessment factor (AF). Differences in “expert judgement” resulted in EQS values that differed by a factor up to 20. The largest difference was found between the EQS derived according to the WFD and RACs calculated from the PPP authorisation documents. RACs were always higher than the EQS, by up to a factor of 230. The key cause seems to be the consideration of recovery during PPP authorisation, which is neither compatible with the protection goals of the GSchG and the GSchV nor with the WFD. Conclusions and recommendations The EQS derived for the selected AS ranged between 0.01 μg/l and 1000 μg/l. Clearly, EQS are significantly higher than the general value of 0.1 μg/l for some AS, while being significantly lower for other AS. Consequently, effect based EQS for PPP are needed for a comprehensive ecotoxicological water quality assessment in Switzerland. For EQS derivation PPP authorisation data are highly relevant and should be included in the data set where appropriate. The hazard assessment procedures of the PSMV, however, have not shown to be compatible with the GSchG. It is recommended that EQS should be derived according to the TGD for EQS, but the protection goals underlying the GSchG and the GSchV should be used as additional guidance during the selection of relevant data. It is further recommended that the Klimisch scoring system for the assessment of data reliability should be revised or amended, since it does not seem to ensure consistent validation between different hazard assessors. In addition, the importance of implementing mixture toxicity approaches into regulatory frameworks has been recognised internationally. Hence, it should be evaluated in the future, how this can be done with respect to EQS. Finally, a scheme for EQS derivation for AS from PPP has been proposed, that is specifically designed to balance the influence of “expert judgement“.

From November 1 2006 to March 31 2010, NEPTUNE joined 18 partner from Europe, Australia and Canada to focus on optimizing wastewater treatment (WorkPackage 1), developing new technologies (WP2), developing methods for assessing micropollutants and toxicity (WP3), improving life cycle analysis of wastewater treatment as a decision supporttool (WP4). PU.

From November 1 2006 to March 31 2010, NEPTUNE joined 18 partner from Europe, Australia and Canada to focus on optimizing wastewater treatment (WorkPackage 1), developing new technologies (WP2), developing methods for assessing micropollutants and toxicity (WP3), improving life cycle analysis of wastewater treatment as a decision supporttool (WP4). PU.

From November 1 2006 to March 31 2010, NEPTUNE joined 18 partner from Europe, Australia and Canada to focus on optimizing wastewater treatment (WorkPackage 1), developing new technologies (WP2), developing methods for assessing micropollutants and toxicity (WP3), improving life cycle analysis of wastewater treatment as a decision supporttool (WP4). PU.

Ozonation as an advanced treatment for micropollutant removal was tested full-scale on the wastewater treatment plant (WWTP) Regensdorf during 16 months. This experiment has been conducted within the project „Strategy Micropoll“ of the Swiss Federal Office for the Environment (FOEN). Ozonation eliminated a broad range of organic micropollutants and various ecotoxicological effects. The pilot study also showed that the implementation of an ozonation step in an existing WWTP is feasible, both technically and economically. The WWTP Regensdorf treats wastewater for the population of around 15'000 inhabitants and 10’000 person equivalents from industry, using a state-of-the-art process with mechanical treatment, activated sludge system for nitrification and denitrification with simultaneous phosphate precipitation followed by sandfiltration of the secondary effluent. The effluent values are within the existing legal limits for classical parameters (e.g. nutrients, organic matter, suspended solids). The wastewater from the WWTP Regensdorf nearly doubles the water flow in the receiving Furtbach creek. During the pilot experiment, ozone was produced from liquid oxygen and mixed with the biologically treated effluent in the existing flocculation tank, which was slightly modified for the experiment. Over 50 different organic micropollutants, which are not completely degraded in the WWTP during secondary treatment, were investigated with chemical trace-analysis (e.g. hormone-active substances, biocides, pharmaceuticals). Some of these substances lead to adverse effects in Swiss surface waters strongly influenced by treated waste water, as it has been shown for the endocrine disruptors. Ozonation resulted in a significant reduction both of the number of measurable substances and their concentrations in the final effluent. For example the whole group of antibiotics and other problematic substances were completely removed even at low ozone doses. However, iodinated X-ray contrast media were only partially removed. The efficiency of ozonation therefore depends on both the ozone dose and the characteristics of specific substances. The results of the chemical trace analysis were confirmed by various ecotoxicological assays, where for example a complete elimination of estrogenicity and herbicidal effects was observed.

Micropollutants from municipal wastewater generally influence the water quality of rivers with a high amount of municipal wastewater. They might also affect water bodies that have an important function as drinking water resources. For micropollutants from municipal wastewater, we distinguish four different input pathways into surface waters: (1) Input with treated wastewater through wastewater treatment plants; (2) input with untreated wastewater through sewer overflows if the capacity of the sewer system or the wastewater treatment plant is exceeded; (3) input through leaks in the sewer network or wrongly connected sewers; and (4) input of polluted rainwater from roofs and sealed areas through rainwater channels. Because many micropollutants are not considerably degraded in conventional wastewater treatment plants, the major part of them enters the surface waters with the treated wastewater effluents of wastewater treatment plants.Using a prioritization procedure, 47 Swiss-specific micropollutants were identified out of 250 candidate substances. The selected Swiss-specific micropollutants are representative for the contamination caused through micropollutants from municipal wastewater. Beside the Swiss-specific micropollutants, locally appearing chemicals from commerce and industry might be of importance. This has to be considered depending on the particular situation. For the ascertainment of micropollutants in surface waters, we suggest a procedure in two steps: (1.) Identification of potentially contaminated waterbodies; and (2.) detailed assessment of the potentially contaminated waterbodies. In the first step, mainly estimations are used, such as the estimation of the wastewater fraction in the waterbodies. In the second step, for a more detailed assessment, different sampling strategies and a selection of the Swiss-specific micropollutants for chemical analysis is suggested. The proposed sampling strategies focus mainly on the determination of the basic contamnation through continuously through municipal wastewater entering substances. For the evaluation of the water quality, the measured data are compared to ecotoxicologically based quality criteria. Therefore, based on the technical guidance document for environmental quality standards of the EU, quality criteria were derived. For the assessment of the water quality, predicted environmental concentrations (PEC) are compared to annual average environmental quality standards (AA-EQS). Based on the Modular Stepwise Procedure (MSK) of the federal office for environment (FOEN), the water quality is divided into five classes: excellent / good / moderate / unsatisfying / poor. Based on the presented assessment concept, further investigations can be prioritized, and reduction strategies and measures for the reduction of micropollutants from municipal wastewater can be evaluated.

Micropollutants from municipal wastewater generally influence the water quality of rivers with a high amount of municipal wastewater. They might also affect water bodies that have an important function as drinking water resources. For micropollutants from municipal wastewater, we distinguish four different input pathways into surface waters: (1) Input with treated wastewater through wastewater treatment plants; (2) input with untreated wastewater through sewer overflows if the capacity of the sewer system or the wastewater treatment plant is exceeded; (3) input through leaks in the sewer network or wrongly connected sewers; and (4) input of polluted rainwater from roofs and sealed areas through rainwater channels. Because many micropollutants are not considerably degraded in conventional wastewater treatment plants, the major part of them enters the surface waters with the treated wastewater effluents of wastewater treatment plants.Using a prioritization procedure, 47 Swiss-specific micropollutants were identified out of 250 candidate substances. The selected Swiss-specific micropollutants are representative for the contamination caused through micropollutants from municipal wastewater. Beside the Swiss-specific micropollutants, locally appearing chemicals from commerce and industry might be of importance. This has to be considered depending on the particular situation. For the ascertainment of micropollutants in surface waters, we suggest a procedure in two steps: (1.) Identification of potentially contaminated waterbodies; and (2.) detailed assessment of the potentially contaminated waterbodies. In the first step, mainly estimations are used, such as the estimation of the wastewater fraction in the waterbodies. In the second step, for a more detailed assessment, different sampling strategies and a selection of the Swiss-specific micropollutants for chemical analysis is suggested. The proposed sampling strategies focus mainly on the determination of the basic contamnation through continuously through municipal wastewater entering substances. For the evaluation of the water quality, the measured data are compared to ecotoxicologically based quality criteria. Therefore, based on the technical guidance document for environmental quality standards of the EU, quality criteria were derived. For the assessment of the water quality, predicted environmental concentrations (PEC) are compared to annual average environmental quality standards (AA-EQS). Based on the Modular Stepwise Procedure (MSK) of the federal office for environment (FOEN), the water quality is divided into five classes: excellent / good / moderate / unsatisfying / poor. Based on the presented assessment concept, further investigations can be prioritized, and reduction strategies and measures for the reduction of micropollutants from municipal wastewater can be evaluated.

Das Programm "Nationale Daueruntersuchung der schweizerischen Fliessgewässer" (NADUF) verfolgt seit 1972 die Entwicklung der Konzentrationen und Frachten relevanter Wasserinhaltsstoffe in wichtigen Fliessgewässern. Es trägt damit wesentlich zur Erfüllung des Bundesauftrages bei, Erhebungen über die Wasserqualität durchzuführen. (Gewässerschutzgesetz vom 24. Januar 1991, Art. 57 Absatz 1). In der Vergangenheit standen vor allem die klassischen Problemstoffe (Nährstoffe, Schwermetalle) im Vordergrund. Heute sind aber auch organische Mikroverunreinigungen ins Zentrum der Diskussion gerückt. Aus diesem Grund soll auch mit der anstehenden Revision der Gewässerschutzverordnung durch den gezielten Ausbau von Abwasserreinigungsanlagen (ARAs) der Eintrag von Mikroschadstoffen in die Gewässer vermindert werden. Im diesem Zusammenhang wurde diese Machbarkeitsstudie lanciert, um zu überprüfen, welche Rolle NADUF bei der Überwachung der Gewässerqualität im Hinblick auf Mikroschadstoffe spielen kann und soll.

Engineered metal and metal oxide nanoparticles (NPs) will change in size and surface properties and are expected to agglomerate and partly dissolve, when exposed to the aquatic environment. Toxic effects of some metal ions (e.g. Ag<SUP>+</SUP>, Cd2+, Cu<SUP>2+</SUP>, Zn<SUP>2+</SUP>, etc.) are very well documented. Some nanoparticulate forms of those metals show similar characteristics (e.g. Ag nanoparticles), but it is still not clear whether recorded toxic effects are caused by the particulate or dissolved form, or both. That is why it is of extreme importance to accurately measure dissolved metal and metal oxide nanoparticle fractions in different aquatic conditions. For this study we have selected metal and metal oxide NPs which are increasingly incorporated into a wide range of products and applications: Ag ( 9 coatings), ZnO (2 sizes), Cu (carbon coated; 2 sizes) and CuO (2 sizes). All experiments were performed in an artificial solution (algal growth media) which represents natural water, at 23 0C and no light conditions for a maximum of 19 days. In the experiments with AgNPs the pH was 7.5 and in the experiments with ZnO, Cu and CuO NPs two different pHs were used: 7.6 and 6.1. The dissolved fraction of metals from nanoparticles in aqueous media was measured using DGT (Diffusion Gradients in Thin films) technique. The results were compared with other available techniques, such as dialysis membrane (DM) and ultrafiltration (UF). Ag NPs size, surface charge and particle dissolution was coating dependent and constant throughout the experiment. Good correlation was achieved among the three techniques used for dissolved silver measurements, but DGT measured 2-5 times less Ag. Likely reasons are: difference in pore size, difference in sampling time, release of Ag<SUP>+</SUP> weakly adsorbed on particle surface by UF and DM and/or difference in diffusion of organic Ag complexes. A small part of ZnO NPs agglomerated very fast after the start of the experiment and disappeared from the aqueous media due to sedimentation, or adsorption on the bottles wall. ZnO NPs left in the aqueous media dissolved almost completely, within hours, after the start of the experiment, especially at lower pH (6.1), as indicated by both DGT and ultrafiltration, for both sizes. Most of carbon coated Cu-NPs disappeared from the aqueous media due to agglomeration and sedimentation, especially smaller NPs at lower pH. When compared to total Cu concentrations present in aqueous media, the larger Cu particles dissolved almost completely at lower pH (6.1) within 2 days. Same particles dissolved around 50 % (measured by DGT and UF) at more neutral pH (7.7). The smaller Cu-NP behaved similarly. Significant increase in Cu NPs dissolution with experimental time was recorded for bigger particles at lower pH, only. Significant amount of CuO NPs agglomerated and disappeared from the aqueous solution, except smaller CuO NPs at lower pH. Smaller CuO NPs dissolved almost completely at lower pH, as well as a significant fraction of the larger CuO-NP At higher pH the dissolution was significantly lower (about 10% of the smaller and 1 % of the larger CuO-NP). In comparison to the total Cu amount introduced in aqueous media (0.8 mg/L of Cu from 1 mg/L CuO NPs), there is still significant amount of dissolved copper (50-70% measured by DGT and UF) at lower pH, but very small amount (less than 1%) of dissolved Cu at higher pH after 2 days. DGT and UF techniques produced similar results for Zn and Cu measurements, but DM measured significantly lower values, probably because of Zn<SUP>2+</SUP> and Cu<SUP>2+</SUP> adsorption onto the membrane. The DGT technique performed very well for the measurement of dissolved ions in presence of nanoparticles, but more testing is needed, especially in more complex, natural water composition with natural organic matter.

Mit einem Stollen zwischen Gattikon und dem Zürichsee (Höhe Thalwil) sollen schadenverursachende Hochwasser im Stadtzentrum von Zürich (Hauptbahnhof), sowie in Adliswil und Langnau künftig reduziert und/oder vermieden werden. Der Entlastungsstollen mit einem Schluckvermögen von 300 m³/s soll schätzungsweise alle 5 bis 10 Jahre anspringen, wenn der Abfluss der Sihl 200 bis 250 m³/s übersteigt. Diese Auftretenswahrscheinlichkeit ergibt sich aus den Messungen von 1938 bis 2009 an der Station Sihlhölzli-2176 (www.hydrodaten.admin.ch/de/2176.html#historische_daten; Jährlichkeit von ~10 Jahre für Abfluss von 200 m³/s) sowie den historischen Hochwassern von 1846, 1852, 1874, 1876, 1910 und 1953 (Scherrer, 2007).<br /> Bei der vorliegenden kurzen Beurteilung der Machbarkeit geht es um folgende Aspekte:<br /> • Prüfung der vorgeschlagenen Sihlentlastung durch einen Stollen zum Zürichsee auf <em>"No-go's"</em><br /> • Aufzeigen von allfälligen Konfliktpunkten<br /> • Liste der notwendigen Abklärungen im Rahmen der nachfolgenden Planungsstufen: Elemente für das Pflichtenheft der Umweltverträglichkeitsprüfung und allfällige Hinweise auf Grundlagen.

Ziel des Projektes „Untersuchungen zu Protozoen und mikrobiologischen Summenparametern in Grundwasserleitern der Schweiz“ war es, einen Überblick des mikrobiologischen Zustandes des Schweizer Grundwassers zu erhalten.

Im Folgenden dargestellt sind die monatlichen simulierten vertikalen Profile der Temperatur und der Partikelkonzentrationen im Lago Bianco und im Lago di Poschiavo für die folgenden Simulationen: Standard–Simulation für das hydrologische Jahr 1988 (Seiten 2 bis 25) Standard–Simulation für das hydrologische Jahr 2001 (Seiten 26 bis 49) Standard–Simulation für das hydrologische Jahr 2005 (Seiten 50 bis 73) Standard–Simulation für das hydrologische Jahr 2007 (Seiten 74 bis 97) Simulation für das hydrologische Jahr 1988 mit Wasserentnahme und -einleitung auf 920 m ü. M. (Seiten 98 bis 121) Simulation für das hydrologische Jahr 1988 mit Wasserentnahme und -einleitung auf 900 m ü. M. (Seiten 122 bis 145)

Die Dünnern ist ein 38.4 km langer Nebenfluss der Aare im Kanton Solothurn (Abbildung 1). Sie entspringt ca. 6 km oberhalb von Welschenrohr (760 m ü M) und mündet bei Olten (395 m ü M) in die Aare. Der mittlere Abfluss bei Olten beträgt 3.4 m<SUP>3</SUP> s<SUP>-1</SUP>. Die Dünnern ist durch ein pluviales Abflussregime geprägt. Sie entwässert einen Abschnitt des Solothurner Juras (Einzugsgebiet: 196 km<SUP>2</SUP>) und gehört zum Einzugsbereich des Rheins. Auf den ersten 17 km des Oberlaufs fliesst die Dünnern zwischen der Weissensteinkette im Süden und der Walenmatt im Norden. Die wichtigsten Zuflüsse der Dünnern sind der Bach der Wolfsschlucht (0.9 m<SUP>3</SUP> s<SUP>-1</SUP>) zwischen Welschenrohr und Herbetswil sowie der Augstbach (1.1 m<SUP>3</SUP> s<SUP>-1</SUP>) bei Balsthal. Die Dünnern macht bei Balsthal einen Bogen nach Südosten und durchbricht die erste Jurakette mit der Balsthaler Klus. Bei Oensingen öffnet sich die Klus, und die Dünnern fliesst in das Schweizer Mittelland. Sie wendet sich hier wieder nach Ostnordosten und fliesst parallel zur Jurakette und zur Aare. Sie fliesst dabei durch die grundwasserreiche Schotterebene des Gäus. Das Gefälle der Dünnern beträgt hier nur gerade 0.5 %. Hochwasserereignisse können im Frühjahr während der Schneeschmelze in Kombination mit Regen oder bei lange anhaltenden Niederschlägen im Einzugsgebiet auch in den anderen Jahreszeiten auftreten. Aus den Juratälern wird der Dünnern Geschiebe zugeführt. Die Dünnern hat ein kleines bis mittelgrosses Geschiebeaufkommen im oberen Einzugsgebiet (Schälchli et al. 2005). Geschiebe wird beim Kiesfang in Oensingen entnommen. Die Geschiebeführung ist unterhalb des Kiesfangs deshalb reduziert (Schälchli et al. 2007). Beim Kiesfang wird der Dünnern zudem Wasser entnommen und in den Mittelgäubach (0.2 m<SUP>3</SUP> s<SUP>-1</SUP>) geleitet. Der Mittelgäubach wurde zur landwirtschaftlichen Bewässerung angelegt und verläuft parallel zur Dünnern (Abbildung 1). In Olten nennt man den Mittelgäubauch „Gheidgraben“. Der Gheidgraben mündet oberhalb von Olten in die Dünnern (0.03 m<SUP>3</SUP> s<SUP>-1</SUP>).

Stickstoff ist ein Schlüsselelement für die organische Natur dank seiner Funktion als Nährstoff und als Bestandteil von Eiweissen. Die Menschen haben allerdings mit ihren Entwicklungen in Verkehr, Industrie, Haushalt und Landwirtschaft in den letzten Jahrzehnten grosse Mengen reak-tiver Stickstoffverbindungen in Luft, Boden und Wasser emittiert und damit Konzentrationsstö-rungen in der Umwelt verursacht, die zunehmend negative Auswirkungen auf Umwelt, Biodi-versität und Gesundheit führen. Die Funktionsweisen des Stickstoffkreislaufs in der Landwirtschaft sind dank der Forschung in ihren wesentlichen Grundzügen bekannt. Schwierigkeiten bestehen aber nach wie vor in der Quantifizierung verschiedener Teilflüsse und deren Beeinflussung durch die landwirtschaftli-chen Prozesse. Ebenfalls besteht in der Steigerung der Stickstoffeffizienz in der Landwirtschaft grosser Optimierungs- und damit Forschungsbedarf. Aus diesen Gründen hat das Bundesamt für Landwirtschaft BLW in Zusammenarbeit mit dem Bundesamt für Umwelt BAFU ein Projekt realisiert mit dem Ziel, Forschungslücken zu identifizieren und zu priorisieren. Die vorliegende Studie dokumentiert die Ergebnisse. Folgende Arbeiten wurden ausgeführt: - Interpretation von Ergebnissen der aktualisierten Stoffflussanalyse Stickstoff der Schweiz im Hinblick auf Forschungslücken, - Befragung von Forschenden in der Schweiz und im europäischen Ausland zur aktuellen Stickstoffforschung, - Auswertung von Literatur.

CO (Confidential). Analytical methods, compound occurrence and transformation products The palette of analytical methods available for analyzing micropollutants in wastewater covers a wide variety of compounds: 152 compounds belonging to 16 different classes were applied within this project. Of relevance due to their occurrence and toxic potency are the new methods developed for biocides, UV-filters, benzothiazoles and antivirals: the majority persist wastewater treatment and many are found in surface waters at concentrations justifying more attention within the micropollutant discussion. A major break through of the project is the development of methods for systematic transformation product identification. These are applicable for biological degradation as well as for chemical oxidative treatment.;

Der Verlust von biologischer Vielfalt (Biodiversität) gibt in der Schweiz und weltweit Anlass zu Besorgnis. Fische, Schlüsselkomponenten in Gewässerlebensräumen, sind ein alarmierendes Beispiel. 60 % der in der Schweiz einheimischen Arten sind ausgestorben, vom Aussterben bedroht oder (stark) gefährdet. Der Anglerfang von Bachforellen in Schweizer Fliessgewässern ging zwischen 1980 und 2002 um 60 % zurück (Burkhardt-Holm 2005). Für den Schutz und den Erhalt von Fischbeständen ist neben Lebensraumschutz auch eine nachhaltige fischereiliche Bewirtschaftung entscheidend.

Der Verlust von biologischer Vielfalt (Biodiversität) gibt in der Schweiz und weltweit Anlass zu Besorgnis. Fische, Schlüsselkomponenten in Gewässerlebensräumen, sind ein alarmierendes Beispiel. 60 % der in der Schweiz einheimischen Arten sind ausgestorben, vom Aussterben bedroht oder (stark) gefährdet. Der Anglerfang von Bachforellen in Schweizer Fliessgewässern ging zwischen 1980 und 2002 um 60 % zurück (Burkhardt-Holm 2005). Für den Schutz und den Erhalt von Fischbeständen ist neben Lebensraumschutz auch eine nachhaltige fischereiliche Bewirtschaftung entscheidend.

As shown in previous reports, gravity-driven membrane technology is an attractive option for decentralized water treatment in developing countries providing an absolute barriers for controlling hygiene hazards. The modular construction of membrane modules allows implementation on all possible scales. Furthermore, the costs of the membrane itself have decreased significantly in the last decades. This report describes the limitations of the system and the possibilities to optimize the capacity. In practical application in households, it is expected that the system is not operated continuously but in a daily cycle with standstill periods. The effect of such standstill periods was investigated systematically, and the results were modeled. It was shown that standstill resulted in considerable flux recovery and that the extent of flux recovery depended on standstill time and on the fact if standstill was followed by flushing. If standstill was followed by forward flushing, daily standstill periods up to 8 hrs. did not affect the total capacity of the system, because the increased flux after standstill completely compensated for the period without operation. In systems where no flushing was applied, the standstill resulted in a decrease of the capacity in all regimes investigated. Based on the results found so far, cost calculations were carried out to investigate if gravity-driven systems can become a viable option for decentralized treatment in developing countries and transition countries. It was found that for treatment on a household level, the costs for the membranes are very low: 0.83 - 2.08 $ per household and year depending on the water quality and the stable flux value, corresponding to 0.17-0.42 $ per person and year. For application on a community scale, the costs are a bit higher, because a higher water demand was assumed for this application: In this application the membrane costs amount to 0.33-0.83 $ per person and year. While no pumps, chemicals or other additional equipment is needed, the system layout can be kept very simple, and thus it is expected that the membrane costs are the main cost factor for a gravity-driven system. Thus, it can be expected that the total system costs can be kept well below the WHO standard for drinking water in the poorest communities (< 10 $ per family and year).

Zur Abdichtung von Flachdächern werden flexible Dachabdichtungsbahnen aus Bitumen oder Kunststoffen eingesetzt und zum Schutz vor Umwelteinflüssen mit Additiven ausges-tattet. Da Dachabwasser entweder versickert oder via Regenwasserkanäle und Trennsysteme direkt in die Gewässer geleitet wird, können ausgewaschene Additive zu einer Belastung der betroffenen Gewässer führen. Über diese Auswaschung aus Kunststoffbahnen liegen bis heute keine Befunde vor. Im Rahmen der vorliegenden Studie wurden sowohl Screening-Untersuchungen zur Identi-fikation problematischer Zielverbindungen als auch vertiefte Produktuntersuchungen durchgeführt. Das Vorgehen wurde in Anlehnung an die im Auftrag des Bundesamts für Umwelt und des Amts für Abfall, Wasser, Energie und Luft, Zürich, durchgeführte Untersu-chung der Freisetzung von Mecoprop aus Bitumenbahnen gewählt.

Der Verlust von biologischer Vielfalt (Biodiversität) gibt in der Schweiz und weltweit Anlass zu Besorgnis. Fische, Schlüsselkomponenten in Gewässerlebensräumen, sind ein alarmierendes Beispiel. 60 % der in der Schweiz einheimischen Arten sind ausgestorben, vom Aussterben bedroht oder (stark) gefährdet. Der Anglerfang von Bachforellen in Schweizer Fliessgewässern ging zwischen 1980 und 2002 um 60 % zurück (Burkhardt-Holm 2005). Für den Schutz und den Erhalt von Fischbeständen ist neben Lebensraumschutz auch eine nachhaltige fischereiliche Bewirtschaftung entscheidend.

Der Verlust von biologischer Vielfalt (Biodiversität) gibt in der Schweiz und weltweit Anlass zu Besorgnis. Fische, Schlüsselkomponenten in Gewässerlebensräumen, sind ein alarmierendes Beispiel. 60 % der in der Schweiz einheimischen Arten sind ausgestorben, vom Aussterben bedroht oder (stark) gefährdet. Der Anglerfang von Bachforellen in Schweizer Fliessgewässern ging zwischen 1980 und 2002 um 60 % zurück (Burkhardt-Holm 2005). Für den Schutz und den Erhalt von Fischbeständen ist neben Lebensraumschutz auch eine nachhaltige fischereiliche Bewirtschaftung entscheidend.

Der Verlust von biologischer Vielfalt (Biodiversität) gibt in der Schweiz und weltweit Anlass zu Besorgnis. Fische, Schlüsselkomponenten in Gewässerlebensräumen, sind ein alarmierendes Beispiel. 60 % der in der Schweiz einheimischen Arten sind ausgestorben, vom Aussterben bedroht oder (stark) gefährdet. Der Anglerfang von Bachforellen in Schweizer Fliessgewässern ging zwischen 1980 und 2002 um 60 % zurück (Burkhardt-Holm 2005). Für den Schutz und den Erhalt von Fischbeständen ist neben Lebensraumschutz auch eine nachhaltige fischereiliche Bewirtschaftung entscheidend.

Phosphorus is an important substance for agricultural production of food. Being a limited resource, it is of great interest for regional, as well as global food security. At the same time it presents a pollution problem for the aquatic environment in Sweden since it contributes to eutrophication of surface waters and the Baltic Sea. This study analyses the flow of phosphorus based on consumption and production of food for an average inhabitant of a Swedish city, Linköping, from 1870 until 2000. The study shows the changes in flows within the system of production and consumption of food, as well as between the different processes in this system, such as agriculture, food processing, consumption and waste handling, and output flows to the environment.<BR/> The main changes in this system over time are a) the increasing flow of phosphorus reaching the consumer and hence the waste handling system, b) the increase in the flow of products from animal production, which mainly causes the increase in (a), and most notably c) the increased input of chemical fertilizer.

Artificial tracers are frequently employed to characterize solute residence times in stream systems and infer the nature of water retention. When the duration of tracer application is different between experiments, tracer breakthrough curves at downstream locations are difficult to compare directly. We explore methods for deriving stream solute residence time distributions (RTD) from tracer test data, allowing direct, non-parametric comparison of results from experiments of different durations. Paired short- and long-duration field experiments were performed using instantaneous and constant-rate tracer releases, respectively. The experiments were conducted in two study reaches that were morphologically distinct in channel structure and substrate size. Frequency- and time domain deconvolution techniques were used to derive RTDs from the resulting tracer concentrations. Comparisons of results between experiments of different duration demonstrated few differences in hydrologic retention characteristics inferred from short- and long-term tracer tests. Because non-parametric RTD analysis does not presume any shape of the distribution, it is useful for comparisons across tracer experiments with variable inputs and for validations of fundamental transport model assumptions.

Occurrence and behavior of fluoroquinolone antibacterial agents (FQs) were investigated in hospital wastewaters in Hanoi, Vietnam. Hospital wastewater in Hanoi is usually not treated and this untreated wastewater is directly discharged into one of the wastewater channels of the city and eventually reaches the ambient aquatic environment. The concentrations of the FQs, ciprofloxacin (CIP) and norfloxacin (NOR) in six hospital wastewaters ranged from 1.1 to 44 and from 0.9 to 17 μg l<SUP>–1</SUP>, respectively. Total FQ loads to the city sewage system varied from 0.3 to 14 g d<SUP>–1</SUP>. Additionally, the mass flows of CIP and NOR were investigated in the aqueous compartment in a small wastewater treatment facility of one hospital. The results showed that the FQ removal from the wastewater stream was between 80 and 85%, probably due to sorption on sewage sludge. Simultaneously, the numbers of <I>Escherichia coli</I> (<I>E. coli</I>) were measured and their resistance against CIP and NOR was evaluated by determining the minimum inhibitory concentration. Biological treatment lead to a 100-fold reduction in the number of <I>E. coli</I> but still more than a thousand <I>E. coli</I> colonies per 100 ml of wastewater effluent reached the receiving water. The highest resistance was found in <I>E. coli</I> strains of raw wastewater and the lowest in isolates of treated wastewater effluent. Thus, wastewater treatment is an efficient barrier to decrease the residual FQ levels and the number of resistant bacteria entering ambient waters. Due to the lack of municipal wastewater treatment plants, the onsite treatment of hospital wastewater before discharging into municipal sewers should be considered as a viable option and consequently implemented.

Beryllium-10 and beryllium-7 have been measured in monthly precipitation samples at a high (Jungfraujoch, 46.32°N 7.59°E, 3580 m) and a low (Dübendorf, 47.25°N 8.27°E, 440 m) altitude station in Switzerland from 1998 till today. The average deposition fluxes of <SUP>7</SUP>Be are 380 ± 30 atoms m<SUP>−2</SUP> s<SUP>−1</SUP> in Dübendorf and 320 ± 20 atoms m<SUP>−2</SUP> s<SUP>−1</SUP> at Jungfraujoch, and the fluxes of <SUP>10</SUP>Be are 810 ± 70 atoms m<SUP>−2</SUP> s<SUP>−1</SUP> in Dübendorf and 810 ± 60 atoms m<SUP>−2</SUP> s<SUP>−1</SUP> at Jungfraujoch. The <SUP>10</SUP>Be/<SUP>7</SUP>Be ratio measured at Jungfraujoch (2.4 ± 0.1) is higher than in Dübendorf (2.1 ± 0.1), which is probably caused by a greater share of stratospheric air at Jungfraujoch in which the <SUP>7</SUP>Be content is reduced because of radioactive decay. The ratios correspond to a mean atmospheric residence time of ∼110–120 d. The deposition fluxes show a seasonal change with a summer maximum and a winter minimum. The <SUP>10</SUP>Be/<SUP>7</SUP>Be ratio exhibits a maximum in the first half of the year at Jungfraujoch in accordance with seasonal stratosphere-troposphere exchange (STE) variations. In Dübendorf the maximum occurs 1 month later. An analysis with a two-box model shows that the calculated variability due to seasonally varying STE explains only one third of the observed variability in the <SUP>10</SUP>Be/<SUP>7</SUP>Be ratio. The rest of the variability is caused by local effects, such as the precipitation rate and the larger than average STE variability at the midlatitudes. According to the model calculations, the global mean <SUP>10</SUP>Be/<SUP>7</SUP>Be ratio only varies between 1.1 and 1.5 with a seasonally varying STE. The larger measured values in the midlatitudes point to a latitudinal dependence of the <SUP>10</SUP>Be/<SUP>7</SUP>Be ratio.

Most studies of potentially hazardous substances focus on aspects of their occurrence and fate in the environment (monitoring and modelling studies) to estimate the environmental impact and the potential exposure of humans. In order to evaluate emission sources, to recognise environmental impacts at an early stage, and to take efficient legislative or technical measures, it is essential to know their behaviour in the anthroposphere as a function of time. So far, only very few investigations of this type exist for chemicals. In regular risk assessments, only rather limited knowledge is available concerning the behaviour of chemicals in the anthroposphere (production data, substance quantities in products, recycling rates, emissions occurring during use, <I>etc</I>.) or their lifecycle, and no information at all about their behaviour as a function of time. For this reason, it is these aspects that were investigated in a case study within the framework of the national research programme NRP50 for selected brominated flame retardants with endocrine-disrupting potential (pentabromodiphenyl ether, hexabromocyclododecane) or the potential to degrade to such substances (decabromodiphenyl ether). A dynamic substance flow analysis (SFA) model was performed for Switzerland for the time period 1980-2020. In this review paper (a) we present a summary of typical results (system overview, consumption trends/application patterns, anthropogenic stocks and their changes, emission trends including major sources and environmental fate), (b) we summarize the effectiveness of recent risk-reduction measures in Switzerland and (c) we indicate serious remaining data gaps and recommend further important measures for risk reduction. For the future, we suggest improving the knowledge of the lifecycle of chemicals such as brominated flame retardants by applying SFA as a suitable tool to weight the effect of substance flows with respect to environmental emissions, and to serve as the basis for planning actions and measures to reduce such emissions. This is in line with one major conclusion of the NRP50 consensus platform 'Brominated Flame Retardants'.

Estrogenic exposure has been reported to occur in Swiss rivers, and there is concern that reduced reproductive health, caused by disturbances of the endocrine system, may contribute to the observed decline in brown trout catch. Consequently, we aimed to determine if disturbances of the endocrine system do occur in wild brown trout (<em>Salmo trutta</em>) in Switzerland and, in the affirmative case, if these might affect trout population status. Our first task was to characterize the estrogenicity of Swiss midland rivers that receive effluents from sewage treatment plants (STP). Next, we performed a set of laboratory and field exposure experiments aimed at elucidating how estrogens affect sexual development and reproductive parameters as estrogen-sensitive targets in the life cycle of brown trout. Subsequently, we assessed the demographic status of brown trout populations in the field which were exposed to the cumulative impact of estrogen-active compounds and other stressors. Finally, we integrated the data into a life-cycle model to predict potential population-level consequences of the (xeno)estrogenic exposure. The estrogenicity of 18 Swiss midland rivers was characterized bioanalytically by applying the YES bioassay to water samples and by measuring plasma vitellogenin (VTG) levels in resident brown trout. Generally, estrogenic contamination of the rivers appears to occur only locally and at comparatively low levels (0.2-2 ng/l 17β-estradiol equivalents). In laboratory experiments, potential disruptive effects of estrogens on gonadal differentiation and reproduction of brown trout were investigated. The estrogen-sensitive window of brown trout gonad differentiation was found to differ from other salmonid species. Feminisation of the developing gonads occurred only after exposure to rather high estrogen concentrations. Analysis of VTG mRNA levels indicated that the yolk may accumulate environmental estrogens and act as a long-term reservoir. The experiments to study the effects of prolonged estrogen exposure on reproduction of mature brown trout showed that, while VTG was induced at low concentrations (20 ng/l estrone (E1), 2 ng/l 17β-estradiol (E2) and 400 ng/l 4-nonylphenol (NP)), effects on reproductive parameters such as fertility became evident only at the higher dose (100 ng/l estrone, 10 ng/l 17β-estradiol and 4000 ng/l 4-nonylphenol). For the field study, the river Lützelmurg (Canton Thurgau) was selected as our study site. This river is impacted by the estrogen-active effluents of one sewage treatment plant (STP). Estrogenic levels in the river were found to be highly variable over time, but showed a distinct difference between sites upstream and downstream from the STP effluent - a difference which was also reflected by the VTG levels of caged and resident brown trout. From the brown trout demographic data, it is evident that factors other than estrogen exposure, including habitat quality, strongly influence population structure. The results from the modelling supported this finding and showed that the trout population in the Lützelmurg is likely to be more sensitive to changes of survival rates in the first winter and beyond than to changes in early life stage survival or reproductive parameters. From the overall results of our project, we conclude that a significant influence of estrogenic contamination on brown trout population densities in the majority of Swiss rivers appears not to be likely.

Our studies with <I>Sphingobium xenophagum</I> Bayram show that this bacterial strain degrades α-quaternary 4-nonylphenols by an <I>ipso</I>-substitution mechanism, whereby the nonylphenol substrates are initially hydroxylated at the <I>ipso</I> position to form 4-hydroxy-4-nonylcyclohexa-2,5-dienones (quinols). Subsequently, the α-quaternary side chains are able to detach as short-living cations from these intermediates. Alkyl branches attached to the carbocation help to delocalize and thereby stabilize the positive charge through inductive and hyperconjugative effects, which explains why only alkyl moieties of α-quaternary nonylphenols are released. This view is corroborated by experiments with <I>S. xenophagum</I> Bayram, in which the alkyl chains of the non-α-quaternary 4-(1-methyloctyl) phenol (4-NP<SUB>2</SUB>) and 4-<I>n</I>-nonylphenol (4-NP<SUB>1</SUB>) were not released, so that the bacterium was unable to utilize these isomers as growth substrates. Analysis of dead end metabolites and experiments with <SUP>18</SUP>O labeled H<SUB>2</SUB>O and O<SUB>2</SUB> clearly show that in the main degradation pathway the nonyl cation derived from α-quaternary quinols preferentially combines with a molecule of water to yield the corresponding alcohol and hydroquinone. However, the incorporation of significant amounts of O<SUB>2</SUB>-derived oxygen into the nonanol metabolites derived from degradation of certain α,α-dimethyl substituted nonylphenols by strain Bayram strongly indicates the existence of a minor pathway in which the cation undergoes an alternative reaction and attacks the <I>ipso</I>-hydroxy group, yielding a 4-alkoxyphenol as an intermediate. Additional growth experiments with strain Bayram revealed that also the two alkoxyphenols 4-<I>tert</I>-butoxyphenol and 4-<I>n</I>-octyloxyphenol promote growth. Furthermore, strain Bayram's <I>ipso</I>-hydroxlating activity is able to transform also bisphenol A.

The objectives of this project were to evaluate i) whether the gonad alterations of whitefish (<I>Coregonus lavaretus</I> spp.) in Lake Thun represent abnormal morphological variations specific to this lake, and, if so, ii) whether the malformations are related to chemical exposure, in particular to exposure to endocrine-disrupting compounds (EDCs). Large-scale monitoring data revealed that, although whitefish in other lakes display some background variation of gonad morphology, the situation in Lake Thun, is unique because of the significantly higher prevalence of gonad malformations. The abnormal variations of whitefish gonad morphology include aplasias, compartmentations, fusions, and intersex. In the search for the factor(s) causing the gonad malformations, coregonids were exposed from fertilization up to maturity to Lake Thun water and plankton or to contaminants possibly being present in the lake, including trinitrotoluenes, and naphtalene sulfonates. Since these experiments are still ongoing, a conclusive answer cannot be given yet, but initial observations point to a role of the lake plankton. The possible presence of EDCs in Lake Thun was assessed using bioanalytics and biomarkers. The bioanalytical studies found estrogenic activities in concentrated plankton extracts of Lake Thun, however, estrogenic activities occurred also in plankton extracts of reference lakes. Bioassay-directed fractionation of the plankton samples points to degradation products of natural substances as a cause of the estrogenic activity. Examination of Lake Thun whitefish for EDC biomarkers such as vitellogenin, sex steroid levels or intersex frequency yielded no indications of exposure to EDCs, neither in fish with normal nor in fish with abnormal gonad morphology. Long-term laboratory exposure of developing coregonids to the prototype estrogenic compound, 17β-estradiol, resulted in an increased frequency of intersex gonads, but did not induce the other gonad malformations typical for Lake Thun coregonids. In summing up, the currently available evidence does not support an EDC or chemical etiology of the gonad malformations, however, this preliminary conclusion needs to be substantiated in the ongoing investigations. The project also highlights the need for more detailed knowledge of natural variation in wildlife populations to be able to recognize anthropogenically caused variation.

Key variables in ecosystems tend to operate on widely different time-scales. These time-scales become relevant when a disturbance rocks the ecosystem. Here we try to explain the fast dynamics of plankton and nutrients in the water column of floodplain lakes after disturbances (inundations). We take advantage of natural experiments, that is occasional massive overflow of floodplain lakes with river water. We sampled 10 lakes in two floodplains along the Dutch river Waal monthly for 3 years, capturing the impact of three inundation events. The inundations reset the plankton as well as chemical composition of most lakes to largely the same state. While biologically inert macro-ion data reflected a large and long lasting impact of the river water, dynamics of nutrients, phytoplankton and zooplankton communities between lakes diverged in a few weeks to regimes characteristic for the different lakes. While one spring inundation synchronized plankton dynamics to let the subsequent clear water phase occur at the same moment in different lakes, winter inundations did not have the same effect and apparently dynamics quickly diverged. Our results showed that effects of inundations and other processes that affect the state of the ecosystem should be studied considering the level of the slow components such as the sediment nutrient pool, fish stock and macrophyte communities. Plankton communities and lake water nutrient status give a practically instantaneous reflection of the condition of these slow components.

1. Most of the existing river ecosystem models describe only part of the ecosystem, have site-specific features, and lack an adequate treatment of uncertainty.<BR/>2. We developed a dynamic model of the functional groups of non-filamentous and filamentous algae, scrapers, collector-gatherers and predators of the benthos community in rivers. This model is based on relatively universal model formulations and is intended to be a first submodel for a more complete model of the river ecosystem and the biogeochemical processes in the river.<BR/>3. The model was tested for the River Sihl in Switzerland. To take advantage of prior knowledge of model parameters, to account for their non-identifiability given the measured data, and to consider uncertainty of model parameters and results, Bayesian inference was used to update the prior probability distribution of the model parameters.<BR/>4. The calibrated model showed very good agreement of model results with measured data. None of the posterior parameter marginals showed a conflict with the prior. Some posterior marginals (specific growth rates of the functional groups, specific death rates, parameters characterizing self- and mutual shading of algae, and the critical level of discharge for catastrophic loss) were significantly narrower than the priors, indicating considerable gain of information from the measurements. For other parameters (half-saturation concentrations of algae and invertebrate growth, parameters characterizing temperature dependence of invertebrate growth rates, colonization rates and most coefficients of catastrophic loss), no significant information could be gained from the data. This clearly demonstrated the need for a Bayesian analysis.<BR/>5. The model seems to be a promising step towards a more comprehensive model of the river ecosystem and the biogeochemical processes in the river. However, more efforts are required: In particular, extension of the model by a description of the dynamics of benthic biofilms and nutrient dynamics and application of the (extended) model to more rivers to learn about the dependence of model parameters on river characteristics. The difficulty of finding adequate data sets for testing such and extended models demonstrates the need for comprehensive measurement campaigns that get information of periphyton, benthic invertebrates, benthic biofilms, suspended and sedimented organic particles, suspended organisms and nutrient concentrations and transformation rates in the water column.

All existing <SUP>10</SUP>Be records from Greenland and Antarctica show increasing concentrations during the Maunder Minimum period (MM), 1645-1715, when solar activity was very low and the climate was colder (little ice age). In detail, however, the 10Be records deviate from each other. We investigate to what extent climatic changes influence the <SUP>10</SUP>Be measured in ice by modeling this period using the ECHAM5-HAM general circulation model. Production calculations show that during the MM the mean global <SUP>10</SUP>Be production was higher by 32% than at present due to lower solar activity. Our modeling shows that the zonally averaged modeled <SUP>10</SUP>Be deposition flux deviates by only ∼8% from the average increase of 32%, indicating that climatic effects are much smaller than the production change. Due to increased stratospheric production, the <SUP>10</SUP>Be content in the downward fluxes is larger during MM, leading to larger <SUP>10</SUP>Be deposition fluxes in the subtropics, where stratosphere-troposphere exchange (STE) is strongest. In polar regions the effect is small. In Greenland the deposition change depends on latitude and altitude. In Antarctica the change is larger in the east than in the west. We use the <SUP>10</SUP>Be/<SUP>7</SUP>Be ratio to study changes in STE. We find larger change between 20° N–40° N during spring, pointing to a stronger STE in the Northern Hemisphere during MM. In the Southern Hemisphere the change is small. These findings indicate that climate changes do influence the <SUP>10</SUP>Be deposition fluxes, but not enough to significantly disturb the production signal. Climate-induced changes remain small, especially in polar regions.

The <I>yjbEFGH</I> operon of <I>Escherichia coli</I> was previously shown to be involved in exopolysaccharide production and induced during biofilm formation by osmotic stress; in this communication we investigate some of the factors taking part in its regulation. We show that induction of <I>yjbF’::luxCDABE</I> transcriptional fusion in response to osmotic shock is limited to the early growth phase of batch-grown cells, and is dictated by cell density in an oxygen-related manner: induction was maximal at low cell density and at high oxygen concentrations. The dependency on cell density and oxygen availability was verified in both batch and continuous culture, using either bioluminescence (<I>luxCDABE</I>) or β-galactosidase (<I>lacZ</I>) genes as the reporter system. It is further shown that <I>yjb</I> is also induced by low specific growth rates, even in the absence of osmotic stress. Finally, it is demonstrated that induction of the <I>yjbEFGH</I> operon, though clearly a stress response, is not a part of the general stress regulon under the positive control of RpoS, as it is negatively affected by this sigma factor.

Excited triplet states of organic chromophores, in particular aromatic ketones, are capable of inducing oxidation of a variety of organic compounds. These reactions probably play an important role in the degradation of organic contaminants in sunlit natural waters. The effect of dissolved natural organic matter (DOM) on the oxidation rate of twenty-two aquatic organic contaminants, including phenols, anilines, phenylurea and s-triazine herbicides, and some pharmaceuticals, was investigated using photoexcited benzophenone-4-carboxylate (CBBP) as the oxidant. For about half of the studied compounds, a decrease in depletion rate was observed in the presence of Suwannee River fulvic acid, used as a reference DOM. Also, depletion rates decreased with increasing DOM concentration, as verified for five selected compounds. Such an inhibitory effect of DOM on oxidation is attributed to its antioxidant properties, whereby oxidation intermediates of the contaminants are supposed to be reduced back to their parent compounds. The presented screening study shows that DOM may be a relevant factor for inhibiting the oxidation of many organic contaminants in surface waters and possibly in engineered water treatment systems.

Network-bound infrastructure systems as electricity, gas, water and telecommunications are currently undergoing transformations on various levels and dimensions. Liberalization, technological innovations and socio-cultural dynamics are part of this. For analyzing these ongoing transformation dynamics as well as exploring future developments of utility systems, a theoretical concept is necessary which spans production, consumption and governance, different levels, and also different sectors. This paper argues that the multi-level perspective is a fruitful starting point allowing the identification of interrelated transformation dynamics in production, consumption and governance, but that multi-regime dynamics need more emphasis, particularly in a future oriented analysis.

Technological innovation systems and the multi-level framework are closely related concepts for the study of far-reaching technological change. They draw on common theoretical roots and analyze similar empirical phenomena. However, they have developed rather independent research strands over the past few years. The paper reviews the state of the art of both concepts and explores commonalities as well as differences. Against this background, we outline first elements of a path towards an integrated framework that combines the strengths of the two approaches and allows providing a better understanding of radical innovation processes and socio-technical transformations.

Contamination of groundwaters with geogenic arsenic poses a major health risk to millions of people. Although the main geochemical mechanisms of arsenic mobilization are well understood, the worldwide scale of affected regions is still unknown. In this study we used a large database of measured arsenic concentration in groundwaters (around 20,000 data points) from around the world as well as digital maps of physical characteristics such as soil, geology, climate, and elevation to model probability maps of global arsenic contamination. A novel rule-based statistical procedure was used to combine the physical data and expert knowledge to delineate two process regions for arsenic mobilization: “reducing” and “high-pH/oxidizing”. Arsenic concentrations were modeled in each region using regression analysis and adaptive neuro-fuzzy inferencing followed by Latin hypercube sampling for uncertainty propagation to produce probability maps. The derived global arsenic models could benefit from more accurate geologic information and aquifer chemical/physical information. Using some proxy surface information, however, the models explained 77% of arsenic variation in reducing regions and 68% of arsenic variation in high-pH/oxidizing regions. The probability maps based on the above models correspond well with the known contaminated regions around the world and delineate new untested areas that have a high probability of arsenic contamination. Notable among these regions are South East and North West of China in Asia, Central Australia, New Zealand, Northern Afghanistan, and Northern Mali and Zambia in Africa.

The geochemical behavior of <SUP>10</SUP>Be in the modern Dead Sea hydrological-limnological system was studied in order to evaluate the feasibility of using Dead Sea and Lake Lisan (the late Pleistocene precursor of the Dead Sea) sediments as archives of the variations in the <SUP>10</SUP>Be production rate. <SUP>10</SUP>Be concentrations in detrital and aragonite material from Lake Lisan laminated sediments were compared to those measured in modern dust, terra rossa soil (aeolian in origin), loess from the Negev Desert, flood suspended load and waters along a rain-flood development pathway (the transition from rain to incipient runoff and fully developed floods). <SUP>10</SUP>Be concentrations decreased throughout the flood development profile, from 8.2 × 10<SUP>3</SUP> atoms g<SUP>–1</SUP> in the runoff down to ~1 × 10<SUP>3</SUP> atoms g<SUP>–1</SUP> in Dead Sea brine due to fast removal of <SUP>10</SUP>Be by the soil and dust particles. Thus, most of the <SUP>10</SUP>Be in the lake is contained within the detrital sediments that collect the <SUP>10</SUP>Be transported by particles from the surrounding terrain (e.g. desert dust with 1.6 ± 0.8 × 10<SUP>8</SUP> atoms g<SUP>–1</SUP> and terra rossa soil-material with up to 12.5 ± 0.5 × 10<SUP>8</SUP> atoms g<SUP>–1</SUP>). The high-stand periods of Lake Lisan were characterized by annual deposition of silty-detritus sediments reflecting rapid transfer of desert dust to the lake by floods. Indeed, the bulk sediments of Lake Lisan (in which <SUP>10</SUP>Be is associated mainly with silty-detritus) display <SUP>10</SUP>Be concentrations similar to those of desert dust. This demonstrates that <SUP>10</SUP>Be variations were modulated by climate (i.e., particle transport). Significant positive <SUP>10</SUP>Be peaks (up to 1.6 × 10<SUP>8</SUP> atoms g<SUP>–1</SUP>) appear during intervals of geomagnetic anomalies in Lake Lisan stratigraphy and in the global record (i.e. during the Laschamp geomagnetic event at ~41 ka BP). This indicates that <SUP>10</SUP>Be atmospheric production signal is superimposed on the climatic 10Be variations. We conclude that after "de-trending" of the climatic signal, Lake Lisan sediments may be used as an archive for atmospheric <SUP>10</SUP>Be production.