Die Schweiz hat den Ausstieg aus der Kernenergie beschlossen. Neben erneuerbaren Energiequellen wie der Fotovoltaik will der Bund auch die Wasserkraft ausbauen. Dessen Annahmen zum Potenzial der Wassernutzung halten Fachleute jedoch für unrealistisch. So bringe der Ausbau der Kleinwasserkraft im Vergleich zum ökologischen Schaden wenig. Neue Pumpspeicherkraftwerke seien dagegen nötig.

Populationen von Erd- und Wechselkröten benötigen im ihrem Landlebensraum die Fläche mehrerer Fussballfelder und genügend Strukturen – besonders in Form von Altholzhaufen. Diese Anforderungen erfüllen sogar Schutzgebiete allerdings häufig nicht. Mit dem Anlegen von Altholzhaufen liesse sich die Qualität bestehender Amphibienlebensräume jedoch einfach und kostengünstig stark verbessern.

One of the main causes of diarrhoea and high infant mortality in developing countries is poor sanitation. The challenge for applied research in this field is to develop technological and planning solutions which are adapted to local conditions. This can only be achieved by collaborating closely with NGOs, local communities and the authorities.

Technical and natural processes such as irradiation with ultraviolet light lead to the transformation of chemical substances in aquatic environments. But are environmental risks reduced as a result? Drawing on knowledge of transformation processes, and using chemical and biological analytical methods, Eawag is developing ways of answering this question.

Sustainable strategic planning of Switzerland’s drinking water supply and wastewater management infrastructure has to take future demand and uncertainties into account. Rather than aiming to reduce costs as far as possible, sound solutions seek to optimize benefits over the entire lifespan and are adapted to local conditions. There is no “one-size-fits-all” solution for the country as a whole.

In wastewater treatment, environmentally sound and resource-efficient technologies should also exploit the resources contained in wastewater itself. Radically new approaches such as urine source separation and the recovery of nutrients for urine based fertilizers point the way to a future which goes beyond conventional sewers and wastewater treatment plants.

The major challenge facing aquatic environmental sciences today is to restore freshwater ecosystems so that the services they provide are maintained for future generations. In these efforts, local populations are of fundamental importance, since processes occurring at the local level underlie the functioning of ecosystems.

Society depends both on the direct use of water – for water supply, irrigated agriculture, waste assimilation, hydropower and navigation – and also on ecosystem services provided by the water environment. Safeguarding the provision of these ecosystem services will require that direct human needs for water are met in ways that minimize adverse impacts on the water environment.

Good-quality drinking water contains a wide variety of naturally occurring microorganisms. In fact, microbial processes play an important role in drinking water treatment. However, water quality can be adversely affected by contamination with pathogenic bacteria. New methods permit improved monitoring of drinking water – and a better understanding of fundamental microbiological processes.

Eine der wichtigsten Ursachen für Durchfallerkrankungen und eine hohe Kindersterblichkeit in Entwicklungsländern ist mangelnde Siedlungshygiene. Aufgabe angewandter Forschung ist es, technische und planerische Lösungen zu entwickeln, die den lokalen Gegebenheiten Rechnung tragen. Dies gelingt nur mit einer engen Zusammenarbeit mit Nichtregierungsorganisationen, der lokalen Bevölkerung und den Behörden.

Technische und natürliche Prozesse wie die Bestrahlung mit ultraviolettem Licht führen zur Veränderung chemischer Stoffe in der aquatischen Umwelt. Doch ist die Transformation der Chemikalien gleichzusetzen mit einem reduzierten Umweltrisiko? Basierend auf Wissen über chemische Transformationsprozesse und mithilfe chemischer und biologischer Analytik entwickelt die Eawag Strategien, um Antworten zu finden.

Eine nachhaltige Zukunftsplanung der Schweizer Trinkwasserversorgung und Abwasserentsorgung muss auch zukünftige Bedürfnisse und Unsicherheiten berücksichtigen. Gute Lösungen zeichnen sich dabei weniger durch möglichst geringe Kosten aus, sondern berücksichtigen den optimalen Nutzen über die gesamte Lebensdauer und sind lokal angepasst. Eine Standardlösung für die Schweiz gibt es nicht.

Umwelt- und ressourcenschonende Technologien in der Abwasserreinigung müssen auch eine optimale Nutzung der Ressourcen im Abwasser einschliessen. Völlig neue Konzepte wie die Separierung des Urins direkt an der Quelle und die Aufbereitung von dessen Nährstoffen zu Dünger weisen in eine Zukunft jenseits der konventionellen Kläranlage und Kanalisation.

Die aquatischen Umweltwissenschaften stehen heute vor der grossen Herausforderung, die Lebensräume der Binnengewässer zu renaturieren, damit deren Ökosystemdienstleistungen auch für künftige Generationen zur Verfügung stehen. Dabei spielen lokale Populationen eine zentrale Rolle. Denn sie bilden das Fundament eines funktionierenden Ökosystems.

Die Gesellschaft ist sowohl von der direkten Nutzung der Wasserressourcen abhängig – von der Wasserversorgung über die Bewässerung, Abwasserentsorgung und Energieproduktion bis zur Schifffahrt – als auch von den Ökosystemdienstleistungen der aquatischen Umwelt. Die Sicherstellung von Letzteren kann nur gelingen, wenn wir die negativen Auswirkungen von Ersterem auf die aquatische Umwelt minimieren.

In hochwertigem Trinkwasser kommen natürlicherweise verschiedenste Mikroorganismen vor. Mikrobielle Prozesse spielen bei der Trinkwasseraufbereitung sogar eine bedeutende Rolle. Verunreinigungen mit problematischen Bakterien können die Wasserqualität jedoch beeinträchtigen. Neuartige Verfahren ermöglichen eine bessere Überwachung des Trinkwassers und ein vertieftes Verständnis über die grundlegenden mikrobiologischen Abläufe.

Variations in influent loads pose major challenges for biological wastewater treatment. Could increased biodiversity allow for more stable operation, and does this mean that biodiversity should also be protected in wastewater treatment plants? Using molecular biological methods, we can now quantify biodiversity and specific groups of microorganisms in complex systems.

Schwankende Zulauffrachten stellen die biologische Abwasserreinigung vor grosse Herausforderungen. Kann hier eine erhöhte Biodiversität helfen und ist Biodiversität also auch in der Kläranlage erstrebenswert? Molekularbiologische Methoden erlauben es uns heute, die Artenvielfalt und spezifische Organismengruppen in komplexen Systemen zu quantifizieren.

Wetlands such as the Danube Delta act as huge natural water purification systems: anthropogenic nutrients are removed from the water column and incorporated into biomass. The decomposition of biomass in the Danube Delta gives rise to particularly large amounts of the greenhouse gases methane and carbon dioxide, which are released into the atmosphere.

From 1950 onwards, habitats and species composition in Europe’s lakes have been altered by excessive inputs of nutrients. The new environmental conditions favoured one particular water flea species, and genes were transferred across species via hybridization. Although eutrophication has now been successfully controlled, the original populations have not been re-established.

Carbon dioxide (CO<SUB>2</SUB>) is removed from the natural global cycle and sequestered in lake sediments in the form of organic carbon. But how is CO<SUB>2</SUB> fixation affected by nutrient concentrations and oxygen availability in lake water? To answer this question, Eawag explored the depths of two lakes, carrying out analyses at the molecular level.

In Switzerland, decentralized systems currently play an insignificant role, being used only in remote areas beyond the reach of public sewers. But under what conditions could they be a viable option in this country and other parts of the developed world? And how do researchers and practitioners view the prospects for these systems in developing countries?

Feuchtgebiete wie das Donaudelta funktionieren wie riesige natürliche Kläranlagen: Anthropogene Nährstoffe werden aus der Wassersäule entfernt und in Biomasse eingebaut. Beim Abbau dieser Biomasse entstehen im Donaudelta besonders grosse Mengen der Treibhausgase Methan und Kohlendioxid, die an die Atmosphäre abgegeben werden.

Die übermässige Nährstoffzufuhr ab 1950 hat in Europas Seen Lebensräume und Artenzusammensetzung verändert. Die neuen Umweltbedingungen bevorzugten eine Wasserfloh-Art, und über Mischlinge wurden Gene eingeschleust. Trotz erfolgreicher Bekämpfung der Überdüngung haben sich die ursprünglichen Populationen nicht wieder eingestellt.

Kohlendioxid (CO<SUB>2</SUB>) wird in Seen aus dem natürlichen Kreislauf der Erde herausgenommen und im Sediment in Form von organischem Kohlenstoff eingelagert. Doch welchen Einfluss haben der Nährstoffgehalt und die Sauerstoffverfügbarkeit des Seewassers auf die CO<SUB>2</SUB>-Fixierung? Um diese Frage zu beantworten, ging die Eawag mit der «molekularen Lupe» auf Tauchstation.

Dezentrale Anlagen spielen in der Schweiz derzeit eine unbedeutende Rolle und werden in abgelegenen Regionen fern ab der Kanalisation eingesetzt. Doch unter welchen Bedingungen haben sie auch in der Schweiz und anderen Industrieländern eine Chance? Und wie sieht es in Entwicklungsländern aus? Meinungen aus Forschung und Praxis.

The project describes the implementation of a demonstration pilot plant for wastewater treatment from a school in the slum of Manchay, Lima, Peru. A subsurface horizontal-flow constructed wetland (SSHF-CW) plant was built with glass walls for purposes o dissemination and education. The project reveals the potential of decentralised wastewater treatment plants in low-income peri-urban areas.

Searches for cartographic materials have previously been carried out using conventional library search systems. However, this kind of search method often proves to be inadequate, as the lack of suitable user interfaces means that queries have to be formulated in words. Furthermore, indexing based on geographical names does not adequately describe the spatial dimension of cartographic material, and geographical names also tend to be ambiguous and inclined to change. A web-based geographical search system (geosearch), which analyzes the geographical coordinates of MARC21 field 034, has been developed for the Swiss research portal for maps. The geosearch enables cartographic material to be found quickly and efficiently on the basis of its location and spatial extent via an intuitively accessible user interface. This is achieved with a cleverly devised ranking algorithm (MapRank^®) and an innovative indexing mechanism. The number of search results can also be restricted by applying filters relating to the publication period and map scale.<br /> The geosearch is proving to be a powerful search tool which, in an open-ended search scenario, can be used to find roughly double the amount of relevant cartographic material within a short space of time. The system is intuitive to operate and no previous knowledge is required. It also offers further strengths, such as the ability to search through extremely large quantities of data quickly and independently from the various subject heading systems and thesauri. This makes the geosearch an ideal tool for carrying out map searches in metacatalogs.

The rapidity at which global landscapes are being transformed by environmental change has revived the importance of biological monitoring. Protected areas harbour some of the most biodiverse assemblages on the planet, typically show the least historical impacts from humans and likely represent areas showing natural patterns, process dynamics and fluctuations that can be compared with areas more directly impacted by humans, especially as the human population grows. This paper provides examples of different biomonitoring programmes in three protected areas in Switzerland, ranging from a large experimental flow program and recent lan annex in the Swiss National Park, to a historical analysis of a designated floodplain of national importance. The data (1999 – present) from the experimental flood study have documented substantial changes in biota that have occurred 7–10 years after the initial flood results as the system enters new ecological states. Monitoring of the land annex in the national park since 2000 has allowed documentation of temporal shifts in physico-chemistry and diatoms that were related to environmental changes in Alpine landscapes. The analysis of historical photo’s of the protected floodplain showed the effects of earlier impacts on floodplain structure and function that are evident today. The results demonstrate the kinds of data that can be generated from biomonitoring programmes with different objectives and goals and how these data can be used to understand eco-evolutionary and ecosystem processes better in the face of rapid landscape transformation.

Energy service providers support stationary fuel cells through local field tests, activities in networks and concerted lobbying at the national level. This ‘external’ innovation management opens up opportunities but there are also problems.

The scope of the study was to assess the strengths and weaknesses of existing household level biogas systems treating toilet waste as well as organic kitchen waste. The biogas systems studied had been implemented on Kumbalangi Island in South India within the framework of a Tourism Development Project to improve sanitary conditions. The assessment comprised a technical monitoring of two selected facilities over a period of two months as well as a household level users survey. Results reveal that the systems are working quite satisfactorily and are generating enough biogas to cook the main dishes of a family along with replacing most of the traditional cooking fuel. The treatment efficiency of the organic pollution is as good as to be expected from biogas systems. However, the effluent does not match the legal requirements for use without any restrictions as organic fertilizer or for discharge into surface water bodies without any further treatment. The current investment costs are high as subsidies formerly provided are not available anymore. This severely limits the potential of wide spread replication.

Recent collaborations between Swiss and USA scientists have revealed rapid biological changes in glacial streams following recent glacial recession in the Alps. Our research has documented upward advancement of stream macroinvertebrates in response to changes in stream habitats. Below is an excerpt from our recent publication in Global Change Biology (Finn et al. 2010).

Seit 75 Jahren schon befasst sich die Eawag mit Gewässerschutz an der Schnittstelle zwischen Wissenschaft und Praxis. Die aktuellen und sich abzeichnenden Herausforderungen zum Thema Wasser erfordern ihre wissenschaftliche Forschung, Lehre und Dienstleistung sicher auch weiterhin.

Die Versorgung von Menschen, Tieren und Pflanzen mit genügend sauberem Wasser wird zunehmend kritisch und erfordert ein stärkeres Engagement unserer Gesellschaft. Grundlage dafür ist solides Fachwissen und Verständnis. Wasser prägt das Antlitz und die Funktionsweise der Erdkugel sowie die Biosphäre. Welche besonderen Eigenschaften bewirken diese herausragende Rolle von H<SUB>2</SUB>O?

In laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), the properties of laser-generated aerosols, such as size and composition, are crucial for matrix-independent quantification. In this study, the aerosol particle morphology and elemental composition generated by two state-of-the-art laser systems (ArF excimer nanosecond-UV laser and Ti:sapphire femtosecond-IR laser) were investigated by electron microscopic techniques. Electrostatic sampling of the aerosols directly onto transmission electron microscopy (TEM) grids allowed us to study the morphology and elemental composition of the aerosols using TEM and TEM–EDX (energy dispersive X-ray spectroscopy) analyses, respectively. The results of the electron microscopic studies were finally compared to the LA-ICPMS signals of the main matrix components. The investigations were carried out for non-conducting materials (glass and zircon), metallic samples (steel and brass) and semiconductors (sulfides). The studies confirm that ns-LA-generated aerosols dominantly consist of nanoparticle agglomerates while conducting samples additionally contain larger spherical particles (diameter typically 50 to 500 nm). In contrast to ns-laser ablation, fs-LA-generated aerosols consist of a mixture of spherical particles and nanoparticle agglomerates for all investigated samples. Surprisingly, the differences in elemental composition between nanoparticle agglomerates and spherical particles produced with fs-LA were much more pronounced than in the case of ns-LA, especially for zircon (Si/Zr fractionation) and brass (Cu/Zn fractionation). These observations indicate different ablation and particle formation mechanisms for ns- and fs-LA. The particle growth mechanism for ns-LA is most likely a gas-to-particle conversion followed by agglomeration and additional hydrodynamic sputtering for conducting samples. On the other hand, phase explosion is assumed to be responsible for the mixture of large spherical particles and nanoparticle agglomerates as found for fs-LA-generated aerosols. Based on these mechanisms, the overall temporal elemental fractionation effects in ns-LA-ICPMS seem to occur mainly during the ablation. This effect was not observed for fs-LA-ICPMS despite the element separation into different particle fractions, which, on the other hand, could induce severe ICP-induced fractionation.

The recent low and prolonged minimum of the solar cycle, along with the slow growth in activity of the new cycle, has led to suggestions that the Sun is entering a Grand Solar Minimum (GSMi), potentially as deep as the Maunder Minimum (MM). This raises questions about the persistence and predictability of solar activity. We study the autocorrelation functions and predictability <I>R</I><SUB>L</SUB><SUP>2</SUP>(<I>t</I>) of solar indices, particularly group sunspot number <I>R</I><SUB>G</SUB> and heliospheric modulation potential Φ for which we have data during the descent into the MM. For <I>R</I><SUB>G</SUB> and Φ, <I>R</I><SUB>L</SUB><SUP>2</SUP>(<I>t</I>) > 0.5 for times into the future of <I>t</I>≈ 4 and ≈ 3 solar cycles, respectively: sufficient to allow prediction of a GSMi onset. The lower predictability of sunspot number <I>R</I><SUB>Z</SUB> is discussed. The current declines in peak and mean <I>R</I><SUB>G</SUB> are the largest since the onset of the MM and exceed those around 1800 which failed to initiate a GSMi.

Background: Environmental stress can result in strong ecological and evolutionary effects on natural populations, but to what extent it drives adaptive divergence of natural populations is little explored. We used common garden experiments to study adaptive divergence in embryonic and larval fitness traits (embryonic survival, larval growth, and age and size at metamorphosis) in eight moor frog, <I>Rana arvalis</I>, populations inhabiting an acidification gradient (breeding pond pH 4.0 to 7.5) in southwestern Sweden. Embryos were raised until hatching at three (pH 4.0, 4.3 and 7.5) and larvae until metamorphosis at two (pH 4.3 and 7.5) pH treatments. To get insight into the putative selective agents along this environmental gradient, we measured relevant abiotic and biotic environmental variables from each breeding pond, and used linear models to test for phenotype-environment correlations.<BR/> Results: We found that acid origin populations had higher embryonic and larval acid tolerance (survival and larval period were less negatively affected by low pH), higher larval growth but slower larval development rates, and metamorphosed at a larger size. The phenotype-environment correlations revealed that divergence in embryonic acid tolerance and metamorphic size correlated most strongly with breeding pond pH, whereas divergence in larval period and larval growth correlated most strongly with latitude and predator density, respectively.<BR/> Conclusion: Our results suggest that <I>R. arvalis</I> has diverged in response to pH mediated selection along this acidification gradient. However, as latitude and pH were closely spatially correlated in this study, further studies are needed to disentangle the specific agents of natural selection along acidification gradients. Our study highlights the need to consider the multiple interacting selective forces that drive adaptive divergence of natural populations along environmental stress gradients.

Hydroquinone-1,2-dioxygenase, an enzyme involved in the degradation of alkylphenols in <I>Sphingomonas</I> sp. strain TTNP3 was purified to apparent homogeneity. The extradiol dioxygenase catalyzed the ring fission of hydroquinone to 4-hydroxymuconic semialdehyde and the degradation of chlorinated and several alkylated hydroquinones. The activity of 1 mg of the purified enzyme with unsubstituted hydroquinone was 6.1 μmol per minute, the apparent K<SUB>m</SUB> 2.2 μM. ICP-MS analysis revealed an iron content of 1.4 moles per mole enzyme. The enzyme lost activity upon exposure to oxygen, but could be reactivated by Fe(II) in presence of ascorbate. SDSPAGE analysis of the purified enzyme yielded two bands of an apparent size of 38 kDa and 19 kDa, respectively. Data from MALDI-TOF analyses of peptides of the respective bands matched with the deduced amino acid sequences of two neighboring open reading frames found in genomic DNA of <I>Sphingomonas</I> sp strain TTNP3. The deduced amino acid sequences showed 62% and 47% identity to the large and small subunit of hydroquinone dioxygenase from <I>Pseudomonas fluorescens</I> strain ACB, respectively. This heterotetrameric enzyme is the first of its kind found in a strain of the genus <I>Sphingomonas sensu latu</I>.

<I>Background, aim and scope</I> Ria de Aveiro (Portugal) is a shallow coastal lagoon of high economic and ecological importance. Hardly any data on its chemical pollution by polar organic pollutants are available in literature. This study focused on the presence and sources of a series of phenolic endocrine-disrupting compounds (EDCs) in this area, including parabens, alkylphenolic compounds and bisphenol-A (BPA). A number of possible sources of pollution are present in the area, including the large harbours present in the lagoon, the city of Aveiro and the rivers discharging into the area. A recently constructed submarine wastewater outfall, located a few kilometres from the lagoon inlet has also been suggested as a possible source of pollution to Ria de Aveiro in several publications. The aim of the current field study was to investigate the occurrence and main sources of phenolic endocrine disruptors in Ria de Aveiro.<BR/><I>Materials and methods</I> An extensive sampling campaign was performed, with surface water and wastewater grab samples taken at over 50 locations, in duplicate on different days. Samples were treated using solid phase extraction and analysed by liquid chromatography tandem mass spectrometry.<BR/><I>Results and discussion</I> Concentrations in lagoon water were generally low: not exceeding 20 ng/L for most analytes. Levels in river water exceeded those in the lagoon by a factor 3 to 500 (<I>o</I>-phenylphenol (PhP) and nonylphenoxy ethoxy acetic acids (A<SUB>9</SUB>PEC), respectively), with concentrations up to 700 ng/L for BPA and 7,300 ng/L for A<SUB>9</SUB>PEC. Samples from the harbours showed EDC levels similar to those in the rest of the lagoon, but in the city of Aveiro, elevated concentrations were observed for alkylphenol ethoxylates (A<SUB>9</SUB>PEO), A<SUB>9</SUB>PEC, PhP and BPA. Wastewater effluents showed low levels for parabens, whilst alkylphenolic compounds reached several micrograms per litre. The effluents are discharged into the ocean via a submarine outfall, but as marine water near the outfall showed slightly elevated concentrations only for A<SUB>9</SUB>PEO, it does not seem to be a significant source of these EDCs for the area.<BR/><I>Conclusions</I> All the studied phenolic EDCs were detected in the study area, with high levels found in some of the rivers discharging into the lagoon, and generally low concentrations in the lagoon itself. The main sources for all investigated EDCs were the rivers Caster and Antuã which discharge into the lagoon. The city of Aveiro was identified as a secondary source. As the tidal water exchange volume is much larger than the freshwater input from the rivers, concentrations of phenolic EDCs remained low in the lagoon.

The spatiotemporal changes in abundance and biomass of heterotrophic bacteria, of three major bacterial phylogenetic groups, and of picocyanobacteria in the upper 20 m of a deep prealpine lake (Lake Zurich, Switzerland) were monitored during a seasonally persistent bloom of the toxigenic filamentous cyanobacterium <em>Planktothrix rubescens</em>. In addition, bacterial 16S ribosomal deoxyribonucleic acid (rDNA) sequences were collected at one instance from the bloom layer and from waters above and below this zone. <em>P. rubescens</em> comprised up to 70% of particulate organic carbon during summer stratification and autumnal mixis and thus by far exceeded the total biomass both of other phytoplankton and of prokaryotes. A strong negative correlation was found between the estimated basin-wide biomass of <em>P. rubescens</em> and of heterotrophic bacteria, and there was different spatial niche preference of filamentous vs. picocyanobacteria. Only members of the <em>Cytophaga–Flavobacterium</em> lineage of <em>Bacteroidetes</em> showed an increasing tendency of association with the <em>P. rubescens</em> population, in particular at the onset of autumnal mixing. Although the filamentous cyanobacterium was the dominant primary producer throughout the year, it did not seem to be a carbon source for heterotrophic bacteria at all. We conclude that <em>P. rubescens</em> represents a powerful competitor of autotrophic and heterotrophic prokaryotes, likely due to both its specific physiological (photoheterotrophic) properties and its protection against zooplankton grazing. This competitiveness might be regarded as another reason for its mass occurrence in numerous lakes of the Northern hemisphere.

Root endophytes are common and genetically highly diverse suggesting important ecological roles. Yet, relative to above-ground endophytes, little is known about them. Dark septate endophytic fungi of the <I>Phialocephala fortinii</I> s.l.–<I>Acephala applanata</I> species complex (PAC) are ubiquitous root colonizers of conifers and Ericaceae, but their ecological function is largely unknown. Responses of Norway spruce seedlings of two seed provenances to inoculations with isolates of four PAC species were studied <I>in vitro</I>. In addition, isolates of <I>Phialocephala subalpina</I> from two populations within and one outside the natural range of Norway spruce were also included to study the effect of the geographic origin of <I>P. subalpina</I> on host response. The interaction of PAC with Norway spruce ranged from neutral to highly virulent and was primarily isolate-dependent. Variation in virulence was much higher within than among species, nonetheless only isolates of <I>P. subalpina</I> were highly virulent. Disease caused by <I>P. subalpina</I> genotypes from the native range of Norway spruce was more severe than that induced by genotypes from outside the natural distribution of Norway spruce. Virulence was not correlated with the phylogenetic relatedness of the isolates but was positively correlated with the extent of fungal colonization as measured by quantitative real-time PCR.

Patchiness is hierarchically structured in stream ecosystems and transcends multiple spatial and temporal scales. Regulation of streams through channelization and flow stabilization often homogenizes in-stream habitats, thereby reducing this patchiness. We conducted a patch-disturbance experiment with individual brick substrata in 2 reaches (open vs closed canopy) and 2 seasons (summer vs winter) in a eutrophic regulated stream. Although the stream was regulated, we expected coarse-scale attributes (canopy cover, season) to influence the effects of disturbance at the fine scale of individual bricks. Brick substrata had 3 degrees of structural complexity (low = smooth, intermediate = techno, high = hetero). Replicates of each brick type were physically disturbed at frequencies of every 5 and 10 d or were left undisturbed during each 30-d experimental period. At the end of each experiment, individual bricks were collected, periphyton biomass was estimated, and macroinvertebrates were identified and counted. Natural densities, taxon richness, and assemblage composition of macroinvertebrates differed significantly between sites and seasons. Periphyton biomass was higher in the open-canopy than in the closed-canopy site in both seasons, especially summer. Periphyton biomass differed among brick types at each site and season, but disturbance had no effect on periphyton biomass within a brick type. At the closed-canopy site, undisturbed hetero bricks had higher macroinvertebrate density, richness, and biomass than the other brick types and disturbance treatments in both seasons. At the open-canopy site, no effect of disturbance was found for any brick type in summer, whereas undisturbed and 10-d hetero bricks had higher macroinvertebrate density, richness, and biomass than the other brick types and disturbance treatments in winter. Besides the dominant role of site and season in this study, our results also suggest that substrate patch complexity can be significant in the response of macroinvertebrates to physical disturbance in regulated streams. As in natural systems, coarse-scale attributes of stream reaches, e.g., degree of canopy cover and season, also provide the spatiotemporal hierarchical context in which disturbance effects are realized in regulated streams, thus having major implications for resource managers.

1.We describe the dynamics of host–parasite interactions over a period of more than 30 years between the freshwater diatom <I>Asterionella formosa</I> and two highly virulent chytrid parasites (<I>Rhizophydium planktonicum</I> and <I>Zygorhizidium planktonicum</I>) in Lake Maarsseveen, The Netherlands. This period is characterised by a significant warming trend which is strongest in spring.<BR/>2. The key spring event in lakes, the diatom bloom, was in many years dominated by <I>Asterionella</I>. We examine whether and how climate warming has affected the prevalence of infection in <I>Asterionella</I> by chytrids.<BR/>3. In years with cold winters/early springs, a dense <I>Asterionella</I> bloom is followed by epidemic development of disease as high <I>Asterionella</I> densities greatly facilitate transmission of chytrid zoospores. This sequence of events is absent in milder winters.<BR/>4. Earlier experimental studies have shown that the parasite is almost non-infective at water temperatures below 3 °C, offering a disease-free window of opportunity for growth of <I>Asterionella</I>. Climate warming has reduced periods in which water temperature remains <3 °C, narrowing the window of opportunity for uninfected growth. Consequently, <I>Asterionella</I> continuously suffers from infection, albeit at low levels.<BR/>5. Population reduction as a result of low level infection allows other diatoms to take over as dominant species, possibly through priority effects.<BR/>6. In mild winters, chytrid infections no longer reach epidemic levels, but remain at low prevalence since transmission is impaired at low host densities. Climate warming thus affects both host and parasite in intricate ways, with the host denied a bloom and consequently the parasite denied an epidemic.<BR/>7. A shift from <I>Asterionella</I> to a mixed diatom community in years with mild winters may benefit the food web, because of the poor edibility of <I>Asterionella</I>, unless the numerous chytrid zoospores produced during epidemics significantly contribute to zooplankton nutrition.<BR/>8. Our study demonstrates the potential complexity of climate change impacts on disease. A reduction in the likelihood of epidemic development of a virulent parasite would seem to be of great benefit to the host, but this was not the case. Unexpected, sometimes paradoxical consequences of climate change can be expected and suggest that the view of a ‘warmer hence sicker world’ may not always apply.

Dissolved organic matter (DOM) samples were obtained from a low-density urbanized area located upstream of Paris (along the Marne River, France) and from the treated effluents at the Paris main wastewater treatment plant. These samples were then fractionated according to their hydrophobicity. DOM fractions consisted of nanomolar to sub-micromolar fresh organic substances with extremely strong Hg-complexing ligands. The conditional stability constants (i.e. <I>K'</I><SUB>HgL</SUB>; pH ∼6.8, <I>I</I><SUB>NaCl</SUB> = 0.5 M, <I>T</I> = 25 °C) of the Hg-DOM complexes formed were greater than 10<SUP>24</SUP> M<SUP>−1</SUP>, for the reaction Hg<SUP>2+</SUP> + L = HgL (with L as ligand). For upstream of Paris, thermodynamic calculations indicated that the vast majority of Hg-DOM was associated with hydrophobic DOM. In contrast, in the Paris main wastewater treatment plant effluents, Hg-DOM was mainly bound to hydrophilic DOM. Simple dilution calculations highlighted that due to the large DOM loading of urban discharges, the hydrophilic urban DOM ligands may commonly dominate Hg-DOM speciation in the downstream Seine River, except under extreme dilution (i.e. high water episodes or floods).

A detailed radiocarbon chronology has been established for the deep-sea core CT85-5 from the Tyrrhenian Sea. This chronology, which is based on the analysis of foraminifera shells, shows a set of reversed <SUP>14</SUP>C ages for sediments deposited during the eruption of the Campanian Ignimbrite (~40 ka cal BP). The anomalous young <SUP>14</SUP>C ages coincide with elevated concentrations of <SUP>10</SUP>Be measured in the same core. Although reversals in <SUP>14</SUP>C ages have been previously found in other records at 40 ka cal BP, such extreme changes have not been observed elsewhere. The enhancement in <SUP>14</SUP>C concentration in CT85-5 sediments associated with the Campanian Ignimbrite is equivalent to an apparent age ~15 ka younger than the age for the sediments deposited shortly before the eruption. Here, we present consistent results of repeated measurements showing no analytical problems that can explain the observed rapid changes in <SUP>14</SUP>C of this particular record.

The water level in Lake Powell, an important water-supply reservoir on the Colorado River, United States, decreased in most years from 1999 to 2010, exposing the sediment delta in the inflow region of this reservoir. This study assesses the potential for sediment-associated phosphorus (P) to enter the water column during sediment resuspension. We collected sediment samples from the reservoir inflow region and performed a sequential extraction and a sorption experiment that focused on P. We also collected water samples at locations upstream and downstream of the exposed sediment delta and measured soluble reactive P during base flow and during the yearly flood associated with spring runoff. Results indicate that extractable P is associated with various operationally defined fractions as follows: 50% with calcite and biogenic apatite, 29% with detrital apatite, 10% with Fe(III)-oxide minerals, 6% with organic matter and 4% with easily exchangeable solid-phase association sites. Sorption experiments indicate that the equilibrium P concentration is 0.19 ± 0.07 μM. Particle size is correlated with sediment P; coarse sediment contains and sorbs much less extractable P than fine sediment does. Measurements of water samples indicate that sediment resuspension probably releases P from sediment to overlying water during base flow, but the effect during floods is less clear. These results indicate that lowering reservoir levels introduces sediment-associated P to the reservoir when sediment resuspension occurs.

Size-exclusion chromatography in combination with organic carbon detection (SEC-OCD) is an established method to separate the pool of NOM into major fractions of different sizes and chemical functions and to quantify these on the basis of organic carbon. One specific approach, also known as LC-OCD-OND, is based on the <I>Gräntzel</I> thin-film UV-reactor. This approach is described with recent improvements in fraction assignation (humic substances, biopolymers, building blocks, low molecular weight organic acids and neutrals, hydrophobic organic carbon), the coupling of a novel organic nitrogen detector (OND), and an improved diagram for the characterisation of aquatic humic substances (HS-diagram). The diagram replaces the operational distinction between humic and fulvic acids by a continuum ranging from aquagenic fulvic acids to pedogenic humic acids.

Gravity-driven, dead-end ultrafiltration of surface water, performed at ultra-low pressures without backflushing, cross-flow or chemical cleaning, results in flux stabilization during extended periods of time. This principle can be used for direct ultrafiltration of surface water without an external energy supply and low maintenance for decentralized drinking-water treatment. Here we investigate the mechanisms of membrane fouling and flux stabilization during gravity-driven, ultra low-pressure UF (ULP-UF). The impact of natural organic matter on the structure and resistance of the fouling layer is studied for different types of water, namely river water, pre-treated river water, river water with addition of sodium azide, aerobic diluted wastewater, diluted wastewater with a low dissolved oxygen content and river water spiked with humic acids or kaolin. Our results show that the deposition of non-dissolved material, biologically induced structural changes in the fouling layer and development of irremovable fouling are three major processes determining the fouling and flux stabilization in ULP-UF. The biologically induced structural changes in the fouling layer lead to heterogeneous structures and channel networks there and cause a decrease of the specific resistance of this layer over time. Flux stabilization occurs when the decrease of the resistance due to structural changes in the fouling layer balances the increase of resistance due to deposition and irremovable fouling.

Constraining variations in marine N<SUB>2</SUB>-fixation over glacial-interglacial timescales is crucial for determining the role of the marine nitrogen cycle in modifying ocean productivity and climate, yet paleo-records from N<SUB>2</SUB>-fixation regions are sparse. Here we present new nitrogen isotope (<I>δ</I><SUP>15</SUP>N) records of bulk sediment and foraminifera test-bound (FB) nitrogen extending back to the last ice age from the oligotrophic Gulf of Mexico (GOM). Previous studies indicate a substantial terrestrial input during the last ice age and early deglacial, for which we attempt to correct the bulk sediment <I>δ</I><SUP>15</SUP>N using its observed relationship with the C/N ratio. Both corrected bulk and FB-<I>δ</I><SUP>15</SUP>N reveal a substantial glacial-to-Holocene decrease of <I>δ</I><SUP>15</SUP>N toward Holocene values of around 2.5 ‰, similar to observations from the Caribbean. This <I>δ</I><SUP>15</SUP>N change is most likely due to a glacial-to-Holocene increase in regional N<SUB>2</SUB>-fixation. A deglacial peak in the FB-<I>δ</I><SUP>15</SUP>N of thermocline dwelling foraminifera <I>Orbulina universa</I> probably reflects a whole ocean increase in the <I>δ</I><SUP>15</SUP>N of nitrate during deglaciation. The <I>δ</I><SUP>15</SUP>N of the surface dwelling foraminifera <I>Globigerinoides ruber</I> and the corrected bulk <I>δ</I><SUP>15</SUP>N show little sign of this deglacial peak, both decreasing from last glacial values much earlier than does the <I>δ</I><SUP>15</SUP>N of <I>O. universa</I>; this may indicate that <I>G. ruber</I> and bulk N reflect the euphotic zone signal of an early local increase in N<SUB>2</SUB>-fixation. Our results add to the evidence that, during the last ice age, the larger iron input from dust did not lead to enhanced N<SUB>2</SUB>-fixation in this region. Rather, the glacial-to-Holocene decrease in <I>δ</I><SUP>15</SUP>N is best explained by a response of N<SUB>2</SUB>-fixation within the Atlantic to the deglacial increase in global ocean denitrification.

Conservation scientists have noted that conservation managers rarely use scientific information when making decisions. One of the reasons why managers rarely use scientific information may be that conservation scientists rarely provide their knowledge in a way that can directly be used by conservation practitioners. Here we show how quantitative recommendations for conservation can be derived. Previous research on terrestrial habitat selection behavior of toads (<I>Bufo bufo</I> and <I>Bufo viridis</I>) showed that wood deposits are a key resource in the terrestrial habitat. We used habitat-dependence analysis to estimate the amount of this key resource, wood deposits, that individual toads require. Based on these estimates we then quantify the requirements for wood deposits for a population. Additionally, we quantified the area that a population requires. Although wood deposits vary strongly in size, we found little evidence for size preferences: only one species preferred smallest sizes of wood deposits. We report all the estimates in a way that can be directly used by conservation managers. Habitat-dependence analysis is a simple and useful tool to quantify habitat requirements. Provisioning of wood deposits may improve the quality of terrestrial habitat for amphibians. Thereby, managers may increase the carrying capacity of terrestrial habitats and support elevated population densities.