This study discusses the results of the continuous monitoring of nitrous oxide emissions from the oxidation tank of a pilot conventional wastewater treatment plant. Nitrous oxide emissions from biological processes for nitrogen removal in wastewater treatment plants have drawn great attention over the last years, due to the high greenhouse effect. However, even if several studies have been carried out to quantify nitrous oxide emission rates from different types of treatment, quite wide ranges have been reported. Only grab samples or continuous measurements over limited periods were considered in previous studies, which can account for the wide variability of the obtained results. Through continuous monitoring over several months, our work tries to fill this gap of knowledge and get a deeper insight into nitrous oxide daily and weekly emission dynamics. Moreover, the influence of some operating conditions (sludge age, dissolved oxygen concentration in the oxidation tank, nitrogen load) was studied to determine good practices for wastewater treatment plant operation aiming at the reduction of nitrous oxide emissions. The dissolved oxygen set-point is shown to play a major role in nitrous oxide emissions. Low sludge ages and high nitrogen loads are responsible for higher emissions as well. An interesting pattern has been observed, with quite negligible emissions during most of the day and a peak with a bell-like shape in the morning in the hours of maximum nitrogen load in the plant, correlated to the ammonia and nitrite peaks in the tank.

After having produced drinking water of high quality it is of vital interest to distribute the water without compromising its quality neither by recontamination nor by microbial regrowth. To minimize regrowth, the strategy of distributing biostable water is followed in several European countries. This implies on one hand the production of water that has a low level of growth-supporting nutrients, in particular organic carbon compounds, and, on the other hand, using materials for storage/distribution that have a low biofilm formation potential and from which only low amounts of total organic carbon (TOC) leach into the water phase. Currently, the approval of materials in contact with drinking water relies on two tests, a migration test and a biofilm formation test. Here we describe an extended migration testing procedure that allows to obtain information not only on the amount of chemical compounds but also on the amount of growth-supporting compounds leaching into the water. In short, the test developed combines several migration cycles and subsequent measurement of the TOC with a novel, fast and reliable test method for determining the assimilable organic carbon (AOC) in the migration waters. AOC gives an indication on the growth-supporting properties of the material. Thus, an initial characterisation of a material with respect to its suitability for usage in contact with drinking water can be performed in a single assay. Results obtained with the new assay for a number of materials typically used in drinking water and sanitary installations are reported.

1.River restoration projects usually aim at improving the physical habitat for aquatic organisms. The extent to which biogeochemical processes and microbial activities are intensified in restored river reaches remains uncertain.<BR/>2. Here, we investigated the relationships between the distribution and composition of organic carbon (OC), bacterial secondary carbon production and extracellular enzymatic activity (EEA) in the ground water below a restored riparian section of the River Thur, Switzerland, relative to a channelised section. The spatiotemporal variability in the stable C isotopic ratio, dissolved OC polydispersity (the distribution of molecular mass in a mixture of molecules) as well as bacterial abundance, EEA and secondary production were investigated in different process zones.<BR/>3. At high river discharge, humic as well as low molecular weight amphiphilic substances infiltrated into the subsurface in a zone dominated by the pioneer plants <I>Salix viminalis</I> (willow bush). Concurrently, bacterial abundance, EEA and secondary carbon production increased at this location.<BR/>4. The willow plants leached bioavailable substrates into the ground water when the water table was high. The flood-driven soil–groundwater coupling stimulated EEA and bacterial secondary production of the suspended groundwater bacterial community.<BR/>5. Establishing riparian habitat diversity adds hot spots of OC inputs during flood events, potentially providing valuable ecosystem services (e.g. degradation of organic pollutants) that accompany.

The colloidal stabilities of ten carbon nanotubes (CNTs) having varying physico-chemical properties were compared in long-term experiments. The presence of Suwannee River Humic Acid (SRHA) increased the fraction of CNTs in the supernatants (4–88% for the various CNT types) after addition in pre-dispersed form and 20 days of shaking and 5 days of settling. These suspensions were monomodal, containing individually suspended CNTs with highly negative surface charges. Calcium (2 mM) removed most of the CNT types from the supernatant, due to CNT-agglomerate formation initiated by reduction in surface charge. The amount of SRHA adsorbed to the different CNT types did not correlate (<I>r</I><SUP>2</SUP> < 0.1) with the percentage of CNTs remaining in suspension. Multiple linear regression analysis revealed that the oxygen content and the diameter of the CNTs significantly influenced the percentage of stabilized CNTs, resulting in an increased fraction of functionalized and large-diameter CNTs that remained in suspension.

This study presents an advanced model for calculating water levels on impervious areas. The approach combines information about rain intensity and flow condition to dynamically determine overland roughness values. When water levels on profiled surfaces of less than 500 m are calculated, the full dynamic wave approximation is necessary because the transition of flow differs compared to kinetic wave theory at the beginning of the runoff event. The application of the model to a civil airport demonstrates how the frequency of critical water levels changes when the cutting of grooves into the runways is considered. The local storm water characteristics are defined by heavy convective precipitation during summer. A critical event was presumed when the water level may cause aquaplaning. The results present a reduction of the number of critical events during a period of 10 years by 68%, even without recognizing the additional friction by the grooves. If increasing friction was included, the remaining frequency would be 0.2 times per year.

Le sédiment constitue un compartiment dynamique et essentiel dans les écosystèmes aquatiques. Il joue un rôle important pour de nombreux animaux et végétaux en tant qu’habitat ou site de ponte. Cependant, il présente la caractéristique d’adsorber des polluants, pouvant être toxiques pour les organismes, et agissant alors comme un réservoir et une source secondaire de contamination à long-terme. Sa surveillance est donc nécessaire pour protéger l’intégrité écologique des écosystèmes aquatiques.

This article addresses how and to what extent a governance mode can legitimately provide public services. A single case study of the partially privatized Berlin Waterworks is used to analyse the level of input and output legitimacy as well as potential trade-offs between the criteria emerging in a public– private partnership (PPP) in the water supply and sanitation sectors. While the Berlin Waterworks as a PPP leads to a lower level of resource protection and public acceptance, it leads to a higher level of efficiency and profitability than under the previous public model.

Peatland testate amoebae are widely used to reconstruct paleohydrological/climatic changes, but many species are also known to respond to pollutants. Peatlands around the world have been exposed to anthropogenic and intermittent natural pollution through the late Holocene. This raises the question: can pollution lead to changes in the testate amoeba paleoecological record that could be erroneously interpreted as a climatic change? To address this issue we applied testate amoeba transfer functions to the results of experiments adding pollutants (N, P, S, Pb, O<SUB>3</SUB>) to peatlands and similar ecosystems. We found a significant effect in only one case, an experiment in which N and P were added, suggesting that pollution-induced biases are limited. However, we caution researchers to be aware of this possibility when interpreting paleoecological records. Studies characterising the paleoecological response to pollution allow pollution impacts to be tracked and distinguished from climate change.

Diurnal fluctuations of dissolved oxygen (DO) concentration and pH due to photosynthesis and respiration are commonly observed in rivers that support periphyton growth. Diurnal fluctuations of electrical conductivity (EC) in connection with photosynthesis have also been reported, but mostly in small, first-order streams or in streams fed by karst springs. The objective of this study is to examine the diurnal EC fluctuations in a large river and understand biological, chemical, and hydrological processes controlling the fluctuations, using long-term archived data, focused field monitoring, and laboratory experiments. The study was conducted in the Thur River draining a 1700 km<SUP>2</SUP> catchment in northeastern Switzerland. The river showed distinct diurnal fluctuations of DO and pH caused by photosynthesis and respiration except during December and part of January. Fluctuations were frequently disrupted by spates with peak discharge exceeding 150 m<SUP>3</SUP> s<SUP>−1</SUP>, which removed biofilm and periphyton. During a period of low flow (12 m<SUP>3</SUP> s<SUP>−1</SUP>) and clear sky, photosynthesis released O<SUB>2</SUB> and consumed CO<SUB>2</SUB> in water during the daytime, thereby increasing pH and the saturation index of calcite. This caused calcite to precipitate and removed Ca and alkalinity from water, and reduced EC. Laboratory experiments showed that the increase in pH and the saturation index alone cannot cause calcite precipitation without the presence of periphyton. It is likely that the precipitation occurs in the microenvironment in the close vicinity of photosynthesizing cells, where the pH and the calcite saturation index are much higher than in the bulk river water. Calcite precipitation stopped during the nighttime despite supersaturated conditions, and EC gradually increased presumably due to the input of Ca and alkalinity by groundwater exchange. The study clearly showed that photosynthesis and calcite precipitation have a strong influence on the chemistry of the large river, and pointed out the need for future research examining the biogeochemical processes in the microenvironment surrounding periphyton, and the roles of river-groundwater exchange processes.

Accurate projections of future climate changes in regions susceptible to drought depend on a good understanding of past climate changes and the processes driving them. In the absence of longer term instrumental data, paleoclimate data are needed. In this study we develop a precipitation reconstruction for Rebecca Lagoon (41°11′S, 144°41′E), northwest Tasmania. First, the relationship between scanning reflectance spectroscopy measurements of sediment cores in the visible spectrum (380–730 nm) and instrumental precipitation record (1912–2009) was used to develop a model to reconstruct precipitation back in time. Results showed that the ratio of reflectance between 660 and 670 nm (i.e., reflectance at 660 nm/reflectance at 670 nm; a measure of pigment diagenesis) was significantly related to annual precipitation. A calibration model was developed (R = − 0.56, p<SUB>auto</SUB><0.001, RMSEP = 43.0 mm yr<SUP>− 1</SUP>, 5 year triangular filtered data, calibration period 1912–2009). Second, this calibration-in-time model was used to reconstruct late Holocene precipitation changes over the last ~3000 years. This showed relatively dry conditions from <I>ca</I>. 3100–2800 cal yr BP, wet conditions from <I>ca</I>. 2800–2400 cal yr BP, dry conditions from <I>ca</I>. 2400–2000 calyr BP, and variable conditions after this. Relatively wet conditions occurred from <I>ca</I>. 500 cal yr BP to the late AD 1800 s (<I>ca</I>. 50 cal. yr BP). The precipitation reconstruction indicates that conditions were relatively dry for the 20th century compared to the last ~3000 years. In particular, the dry period measured in recent decades is one of the most intense in at least the last 500 years. As precipitation in this region is primarily driven by the Southern Hemisphere westerly winds, these changes are discussed in terms of shifts in westerly wind strength and/or position.

A fundamental challenge to our understanding of biodiversity is to explain why some groups of species undergo adaptive radiations, diversifying extensively into many and varied species, whereas others do not<SUP>1,2</SUP>. Both extrinsic environmental factors (for example, resource availability, climate) and intrinsic lineage-specific traits (for example, behavioural or morphological traits, genetic architecture) influence diversification, but few studies have addressed how such factors interact. Radiations of cichlid fishes in the African Great Lakes provide some of the most dramatic cases of species diversification. However, most cichlid lineages in African lakes have not undergone adaptive radiations. Here we compile data on cichlid colonization and diversification in 46 African lakes, along with lake environmental features and information about the traits of colonizing cichlid lineages, to investigate why adaptive radiation does and does not occur. We find that extrinsic environmental factors related to ecological opportunity and intrinsic lineage-specific traits related to sexual selection both strongly influence whether cichlids radiate. Cichlids are more likely to radiate in deep lakes, in regions with more incident solar radiation and in lakes where there has been more time for diversification. Weak or negative associations between diversification and lake surface area indicate that cichlid speciation is not constrained by area, in contrast to diversification in many terrestrial taxa<SUP>3</SUP>. Among the suite of intrinsic traits that we investigate, sexual dichromatism, a surrogate for the intensity of sexual selection, is consistently positively associated with diversification. Thus, for cichlids, it is the coincidence between ecological opportunity and sexual selection that best predicts whether adaptive radiation will occur. These findings suggest that adaptive radiation is predictable, but only when species traits and environmental factors are jointly considered.

Resource polymorphisms and competition for resources are significant factors in speciation. Many examples come from fishes, and cichlids are of particular importance because of their role as model organisms at the interface of ecology, development, genetics and evolution. However, analysis of trophic resource use in fishes can be difficult and time-consuming, and for fossil fish species it is particularly problematic. Here, we present evidence from cichlids that analysis of tooth microwear based on high-resolution (sub-micrometre scale) three-dimensional data and new ISO standards for quantification of surface textures provides a powerful tool for dietary discrimination and investigation of trophic resource exploitation. Our results suggest that three-dimensional approaches to analysis offer significant advantages over two-dimensional operator-scored methods of microwear analysis, including applicability to rough tooth surfaces that lack distinct scratches and pits. Tooth microwear textures develop over a longer period of time than is represented by stomach contents, and analyses based on textures are less prone to biases introduced by opportunistic feeding. They are more sensitive to subtle dietary differences than isotopic analysis. Quantitative textural analysis of tooth microwear has a useful role to play, complementing existing approaches, in trophic analysis of fishes—both extant and extinct.

This article investigates the interplay of expectation dynamics and innovation processes at the level of organizations and at the innovation system level. We examine how different kinds of organizations contributed and responded to a recent hype and disappointment cycle in the field of stationary fuel cells. Among others, we trace how innovation and discourse activities changed and we explain the observed differences in strategic responses. We show that the sensitivity of organizations to expectation dynamics depends on at least three factors: the strategic embedding of the new technology, the organization's dependence on external legitimacy and its role in the innovation system. Moreover, we show that – in their aggregation – strategic responses affected the level of the technological innovation system as well. Not only did the pace and direction of innovation activities change, but structures such as actor constellations and institutions were also modified. Our study thus provides insights into the interplay of expectation and innovation dynamics, which is important for our understanding of larger transformation processes, e.g. toward more sustainable modes of energy supply.

Previous research has shown that formal networks can play a crucial role in the formation of technological innovation systems (TIS). Firms and other actors collaborate in formal networks not only to generate new knowledge but also to strategically create and shape supportive system resources such as technology specific R&D programs. This paper takes a closer look at the resources, which are developed and deployed by networks to facilitate the building up of a TIS. Networks rely not only on the organizational resources of their members but also on new resources developed at the network level including network governance structures, trust among network members, a common understanding of the strategic goals or a good reputation of the network. Our analysis shows that the capacity of networks to fulfill different tasks of system building especially depends on the network resources they are able to establish. With the differentiation of organizational, network and system resources we introduce a conceptual framework, which makes three important contributions. It highlights the strategic nature of (innovation) system building; it allows us comparing the contribution of different actors and formal networks in this regard; and it improves our understanding of how firm and system level processes are intertwined.

We present a lake-wide investigation of Lake Superior carbon and organic matter biogeochemistry using radiocarbon, stable isotope, and carbon concentrations. Dissolved inorganic carbon (DIC) abundance in the lake was 121–122 Tg C, with offshore concentration and <I>δ</I><SUP>13</SUP>C values being laterally homogenous and tightly coupled to the physical and thermal regime and biochemical processes. Offshore Δ<SUP>14</SUP>C of DIC (50–65‰) exhibited lateral homogeneity and was more <SUP>14</SUP>C enriched than co-occurring atmospheric CO<SUB>2</SUB> (∼38‰); nearshore Δ<SUP>14</SUP>C of DIC (36–38‰) was similar to atmospheric CO<SUB>2</SUB>. Dissolved organic carbon (DOC) abundance was 14.2–16.4 Tg C. DOC's concentration and <I>δ</I><SUP>13</SUP>C were homogenous in June (mixed lake), but varied laterally during August (stratification) possibly due to spatial differences in lake productivity. Throughout sampling, DOC had modern radiocarbon values (14–58‰) indicating a semilabile nature with a turnover time of ≤60 years. Lake particulate organic carbon (POC, 0.9–1.3 Tg C) was consistently <SUP>13</SUP>C depleted relative to DOC. The <I>δ</I><SUP>15</SUP>N of epilimnetic particulate organic nitrogen shifted to more negative values during stratification possibly indicating greater use of nitrate (rather than ammonium) by phytoplankton in August. POC's radiocarbon was spatially heterogeneous (Δ<SUP>14</SUP>C range: 58‰ to −303‰), and generally <SUP>14</SUP>C depleted relative to DOC and DIC. POC <SUP>14</SUP>C depletion could not be accounted for by black carbon in the lake but, because of its spatial and temporal distribution, is attributed to sediment resuspension. The presence of old POC within the epilimnion of the open lake indicates possible benthic-pelagic coupling in the lake's organic carbon cycle; the ultimate fate of this old POC bears further investigation.

The Yangtze is the largest river in Asia and its water composition reflects the activities of about 400 Mio people in its catchment. Its chemical loads have a large impact on the biogeochemistry of the East China Sea. We discuss and quantify the annual dynamics of major ions, nutrients, and trace elements from samples collected monthly at Datong Station from May 2009 to June 2010. The Yangtze today carries 192 × 10<SUP>6</SUP> tons of total dissolved solids annually to the East China Sea, which is an increase of 25% compared to the average of 1958–1990. While the loads of dissolved silica (SiO<SUB>2</SUB>), dissolved inorganic carbon (DIC), Ca<SUP>2+</SUP> and Mg<SUP>2+</SUP> compared well with the long-term averages since the 1950s, loads of Na<SUP>+</SUP>, Cl<SUP>−</SUP>, SO<SUB>4</SUB><SUP>2−</SUP>, have tripled since 1958–1990. The increase of SO<SUB>4</SUB><SUP>2−</SUP> is attributed to the burning of coal in the catchment, and 18% of the F<SUP>−</SUP> load is estimated to originate from this source. The increase of Na<SUP>+</SUP> and Cl<SUP>−</SUP> loads may be anthropogenic as well. The load of dissolved inorganic nitrogen (DIN) has increased 15 fold since the early measurements around 1970 and amounts to 1.6 Mt-N/yr today. The particulate concentrations of the typical anthropogenic trace metals Cd, Cr, Cu, Ni, Pb, and Zn showed enrichment factors between 0.7 – 7 compared to the natural background. Their annual peak concentrations all exceeded the quality targets recommended by the EC up to two times. However, the load of trace elements at Datong decreased by 73–86% (As: 50%) in the past ten years.

In this paper, the authors explore the conditions under which a double-diffusive interface may become unstable. Focus is placed on the case of a cold, freshwater layer above a warm, salty layer [i.e., the diffusive convection (DC) regime]. The “diffusive interface” between these layers will develop gravitationally unstable boundary layers due to the more rapid diffusion of heat (the destabilizing component) relative to salt. Previous studies have assumed that a purely convective-type instability of these boundary layers is what drives convection in this system and that this may be parameterized by a boundary layer Rayleigh number. The authors test this theory by conducting both a linear stability analysis and direct numerical simulations of a diffusive interface. Their linear stability analysis reveals that the transition to instability always occurs as an oscillating diffusive convection mode and at boundary layer Rayleigh numbers much smaller than previously thought. However, these findings are based on making a quasi-steady assumption for the growth of the interfaces by molecular diffusion. When diffusing interfaces are modeled (using direct numerical simulations), the authors observe that the time dependence is significant in determining the instability of the boundary layers and that the breakdown is due to a purely convective-type instability. Their findings therefore demonstrate that the relevant instability in a DC staircase is purely convective.

Recent studies have shown that dissolved organic matter (DOM) may inhibit the excited triplet-induced oxidation of several aromatic water contaminants, in particular those containing an aniline functionality. Such an inhibition was ascribed to antioxidant moieties of DOM. The present study was conducted with the aim of verifying whether well-defined antioxidants could act as inhibitors in analogy to DOM. Various substituted phenols exhibiting antioxidant character were able, at micromolar concentration, to slow down the photoinduced depletion of several anilines and sulfonamides in aerated aqueous solution containing 2-acetonaphthone as the photosensitizer. A concomitant accelerated degradation of the phenols in the presence of such contaminants was observed. This reinforces the hypothesis of reduction of oxidation intermediates of the contaminants by the phenols. Phenol (unsubstituted) was found to be a useful inhibitor even in the case of DOM-photosensitized transformations. Phenolic antioxidants are proposed as diagnostic tools to investigate the aquatic photochemistry of aromatic amines.

Real-time quantitative PCR (qPCR) is a widely used technique in microbial community analysis, allowing the quantification of the number of target genes in a community sample. Currently, the standard-curve (SC) method of absolute quantification is widely employed for these kinds of analysis. However, the SC method assumes that the amplification efficiency (<em>E</em>) is the same for both the standard and the sample target template. We analyzed 19 bacterial strains and nine environmental samples in qPCR assays, targeting the <em>nifH</em> and 16S rRNA genes. The <em>E</em> values of the qPCRs differed significantly, depending on the template. This has major implications for the quantification. If the sample and standard differ in their <em>E</em> values, quantification errors of up to orders of magnitude are possible. To address this problem, we propose and test the one-point calibration (OPC) method for absolute quantification. The OPC method corrects for differences in <em>E</em> and was derived from the ΔΔ<em>C</em><em>_T</em> method with correction for <em>E</em>, which is commonly used for relative quantification in gene expression studies. The SC and OPC methods were compared by quantifying artificial template mixtures from <em>Geobacter sulfurreducens</em> (DSM 12127) and <em>Nostoc commune</em> (Culture Collection of Algae and Protozoa [CCAP] 1453/33), which differ in their <em>E</em> values. While the SC method deviated from the expected <em>nifH</em> gene copy number by 3- to 5-fold, the OPC method quantified the template mixtures with high accuracy. Moreover, analyzing environmental samples, we show that even small differences in <em>E</em> between the standard and the sample can cause significant differences between the copy numbers calculated by the SC and the OPC methods.

The goal of this study was to experimentally assess the coupling between primary producer biomass dynamics and the distribution and fate of persistent organic pollutants (POPs) in a lake pelagic ecosystem. This was done by following the short-term evolution of polychlorinated biphenyl (PCB) concentrations in water and biota (phytoplankton and zooplankton) and the variability of bioconcentration (BCF), biomagnification (BMF), and bioaccumulation (BAF) factors during the development of a typical spring ecological progression in which the phytoplankton bloom is followed by a peak in the zooplankton abundance. The bulk of compounds with log <I>K</I><SUB>OW</SUB> > 6.5 in the lake epilimnion was mainly associated with primary producer biomass. The phytoplankton biological pump was a major driver of POP export from the epilimnion, causing the decline of dissolved-phase concentrations. The BCF of phytoplankton for the more hydrophobic PCBs showed minima during the period of biomass climax. The concentration in the zooplankton of all selected PCBs sharply declined from March to May, with BAFs having minima in the post algal bloom phase. Biomagnification occurred during the pre algal bloom and algal bloom phases but appeared to be absent during the post algal bloom. This study highlights the occurrence of a prompt and complex response in the fate and distribution of POPs to dynamic biogeochemical control. Within the frame of the ecological succession, phytoplankton and zooplankton biomass dynamics produced bioaccumulation metrics varying over 1–2 orders of magnitude in the time frame of a few weeks and resulted in reduced trophic web exposure.

The utilization of molecular endpoints in ecotoxicology can provide rapid and valuable information on immediate organismal responses to chemical stressors and is increasingly used for mechanistic interpretation of effects at higher levels of biological organization. This study contributes knowledge on the sublethal effects of a commonly used insecticide, the phenylpyrazole fipronil, on larval fathead minnow (<I>Pimephales promelas</I>), utilizing a quantitative transcriptomic approach. Immediately after 24 h of exposure to fipronil concentrations of ≥ 31 μg.L<SUP>−1</SUP>, highly significant changes in gene transcription were observed for aspartoacylase, metallothionein, glucocorticoid receptor, cytochrome P450 3A126 and vitellogenin. Different mechanisms of toxicity were apparent over the course of the experiment, with short-term responses indicating neurotoxic effects. After 6 days of recovery, endocrine effects were observed with vitellogenin being up-regulated 90-fold at 61 μg.L<SUP>−1</SUP> fipronil. Principal component analysis demonstrated a significant increase in gene transcription changes over time and during the recovery period. In conclusion, multiple mechanisms of action were observed in response to fipronil exposure, and unknown delayed effects would have been missed if transcriptomic responses had only been measured at a single time-point. These challenges can be overcome by the inclusion of multiple endpoints and delayed effects in experimental designs.

Semiarid regions worldwide are particularly prone to eutrophication, which causes immense ecological and economic problems. One region that is in transition and requires systematic research for effective intervention is the dry landscape of Beijing-Tianjin (P. R. China). We investigated the sources and spatiotemporal loads of nitrogen and phosphorus species over a one-year period in the Haihe catchment that drains the megacity of Beijing. Although wastewater treatment was improved in recent years, the rivers were heavily contaminated by 0.3–5.3 mgP L<SUP>–1</SUP> and 3.0–49 mgN L<SUP>–1</SUP>, with toxic levels of nitrite (≥1 mgNO<SUB>2</SUB>–N L<SUP>–1</SUP>) and ammonia (≥0.6 mgNH<SUB>3</SUB>–N L<SUP>–1</SUP>). The average NH<SUB>4</SUB><SUP>+</SUP> (16.9 mgN L<SUP>–1</SUP>) increased by 160% compared to 1996-levels. Mass fluxes and δ<SUP>15</SUP>N-signatures revealed that nutrients originated almost exclusively from sewage. Furthermore, the water balance demonstrated that >90% of the polluted river water was diverted for irrigation, thereby threatening food safety and groundwater quality. Per capita loads of 1.42 kgN/yr and 115 gP/yr were comparable to the peak discharges typical of Europe and the United States in 1970–1990, but concentrations were 2–3 times higher in the Beijing–Tianjin region. Our research identified sewage as the predominant nutrient source in this semiarid region, which suggests that state-of-the-art wastewater treatment would drastically mitigate eutrophication and even more rapidly than was previously observed in Europe.

In the past decade, the literature on transitions toward sustainable socio-technical systems has made a considerable contribution in understanding the complex and multi-dimensional shifts considered necessary to adapt societies and economies to sustainable modes of production and consumption. However, transition analyses have often neglected where transitions take place, and the spatial configurations and dynamics of the networks within which transitions evolve. A more explicit spatial perspective on sustainability transitions contributes to the extant transitions literature in three ways. Firstly it provides a contextualization on the limited territorial sensitivity of existing literature. Secondly, it explicitly acknowledges and investigates diversity in transition processes, which follows from a 'natural' variety in institutional conditions, networks, actor strategies and resources across space. Thirdly, it encompasses not only greater emphasis but also an opportunity to connect to a body of literature geared to understanding the international, trans-local nature of transition dynamics. Concerned with the prevalent lack of attention for the spatial dimensions of sustainability transitions in most studies, this paper seeks to unpick and make explicit sustainability transition geographies from the vantage point of economic geography. The paper argues that there are two interrelated problems requiring attention: the institutional embeddedness of socio-technical development processes within specific territorial spaces, and an explicit multi-scalar conception of socio-technical trajectories. Following these arguments, the paper concludes that transitions research would do well to take a closer look at the geographical unevenness of transition processes from the perspective of global networks and local nodes.

Sustainability oriented innovation and technology studies have received increasing attention over the past 10–15 years. In particular, a new field dealing with "sustainability transitions" has gained ground and reached an output of 60–100 academic papers per year. In this article, we aim to identify the intellectual contours of this emerging field by conducting a review of basic conceptual frameworks, together with bibliographical analysis of 540 journal articles in the field. It is against this background that we position the six papers assembled in a special section in Research Policy. These papers pave the way for new conceptual developments and serve as stepping-stones in the maturation of sustainability transition studies, by linking with the scholarly literatures of management studies, sociology, policy studies, economic geography, and modeling.

The Sun is the main driver of Earth's climate, yet the Sun's role in forcing decadal-to-centennial climate variations has remained controversial, especially in the context of understanding contributions of natural climate forcings to continuing global warming. To properly address long-term fingerprints of solar forcing on climate, long-term, very high-resolution, globally distributed climate proxy records are necessary. In this study we compile and evaluate a near global collection of annually-resolved tree-ring-based climate proxies spanning the past two millennia. We statistically assess these records in both the time and frequency domains for solar forcing (i.e. Total Solar Irradiance; TSI) and climate variability with emphasis on centennial time scales. Analyses in the frequency domain indicate significant periodicities in the 208-year frequency band, corresponding to the DeVries cycle of solar activity. Additionally, results from Superposed Epoch Analysis (SEA) point toward a possible solar contribution in the temperature and precipitation series. However, solar-climate associations remain weak, with for example no clear linkage distinguishable in the southwestern United States drought records at centennial time scales. Other forcing factors, namely volcanic activity, appear to mask the solar signal in space and time. To investigate this hypothesis, we attempted to extract volcanic signals from the temperature proxies using a statistical modelling approach. Wavelet analysis of the volcanic contribution reveals significant periodicities near the DeVries frequency during the Little Ice Age (LIA). This remarkable and coincidental superposition of the signals makes it very difficult to separate volcanic and solar forcing during the LIA. Nevertheless, the "volcano free" temperature records show significant periodicities near the DeVries periodicity during the entire past 1500 years, further pointing to solar mechanisms and emphasising the need for solar related studies in the absence of strong multi-decadal volcanic forcing.

The varved sediments of Lake Van provide a high-quality continental archive of seasonal to decadal-scale climate variability. In order to read the natural record, modern varve formation was studied on the basis of (1) remotely-sensed total suspended-matter (TSM<SUB>rs</SUB>) concentrations; (2) time-series of particle flux and water temperatures; and (3) turbidity, temperature, and oxygen profiles. TSM<SUB>rs</SUB>, validated by contemporaneous water-column sampling, shows great temporal and lateral variations (whitings and turbidity plumes). From 2006 to 2009, sequential sediment traps recorded high particle fluxes during spring and fall, medium fluxes during summer, and almost zero flux during winter. The mean total mass flux of 403 mg m<SUP>− 2</SUP> day<SUP>− 1</SUP> comprised 33% (seasonally up to 67%) calcium carbonate, 7% aquatic organic matter, 6% biogenic opal, and 54% detrital minerals. The CaCO<SUB>3</SUB> fluxes are controlled by river discharge (precipitation and snowmelt) during spring, by high productivity during summer, and by river discharge (precipitation before snowfall starts) and mixing during fall. In November 2007, an anomalously high CaCO<SUB>3</SUB> flux occurred as a result of a warm water surface supersaturated with calcite coinciding with an anomalous runoff event. The results demonstrate that the couplets of light and dark laminae in the short sediment cores are true varves representing spring–summer–fall and winter conditions, respectively. Consequently, varve formation can be linked to the seasonal climate pattern, providing a calibration that can be used to interpret the partially varved paleo-record of Lake Van and related environmental processes.

Antipredator defenses and warning signals typically evolve in concert. However, the extensive variation across taxa in both these components of predator deterrence and the relationship between them are poorly understood. Here we test whether there is a predictive relationship between visual conspicuousness and toxicity levels across 10 populations of the color-polymorphic strawberry poison frog, <I>Dendrobates pumilio</I>. Using a mouse-based toxicity assay, we find extreme variation in toxicity between frog populations. This variation is significantly positively correlated with frog coloration brightness, a viewer-independent measure of visual conspicuousness (i.e., total reflectance flux). We also examine conspicuousness from the view of three potential predator taxa, as well as conspecific frogs, using taxon-specific visual detection models and three natural background substrates. We find very strong positive relationships between frog toxicity and conspicuousness for bird-specific perceptual models. Weaker but still positive correlations are found for crab and <I>D. pumilio</I> conspecific visual perception, while frog coloration as viewed by snakes is not related to toxicity. These results suggest that poison frog colors can be honest signals of prey unpalatability to predators and that birds in particular may exert selection on aposematic signal design.

This study investigates the impact of predation by eukaryotes on the development of specific biofilm structures in gravity-driven dead-end ultrafiltration systems. Filtration systems were operated under ultra-low pressure conditions (65 mbar) without the control of biofilm formation. Three different levels of predation were evaluated: (1) inhibition of eukaryotic organisms, (2) addition of cultured protozoa (<I>Tetrahymena pyriformis</I>), and (3) no modification of microbial community as a control. The system performance was evaluated based on permeate flux and structures of the biofilm. It was found that predation had a significant influence on both the total amount and also the structure of the biofilm. An open and heterogeneous structure developed in systems with predation whereas a flat, compact, and thick structure that homogeneously covered the membrane surface developed in absence of predation. Permeate flux was correlated with the structure of the biofilm with increased fluxes for smaller membrane coverage. Permeate fluxes in the presence or absence of the predators was 10 and 5 L m<SUP>−2</SUP> h<SUP>−1</SUP>, respectively. It was concluded that eukaryotic predation is a key factor influencing the performance of gravity-driven ultrafiltration systems.

Whereas many studies have addressed the mechanisms driving partial migration, few have focused on the consequences of partial migration on trophic dynamics, and integrated studies combining the two approaches are virtually nonexistent. Here we show that temperature affects seasonal partial migration of cyprinid fish from lakes to predation refuges in streams during winter and that this migration in combination with temperature affects the characteristics and phenology of lower trophic levels in the lake ecosystem. Specifically, our six-year study showed that the proportion of fish migrating was positively related to lake temperature during the pre-migration growth period, i.e. during summer. Migration from the lake occurred later when autumn water temperatures were high, and timing of return migration to the lake occurred earlier at higher spring water temperatures. Moreover, the winter mean size of zooplankton in the lake increased with the proportion of fish being away from the lake, likely as a consequence of decreased predation pressure. Peak biomass of phytoplankton in spring occurred earlier at higher spring water temperatures and with less fish being away from the lake. Accordingly, peak zooplankton biomass occurred earlier at higher spring water temperature, but relatively later if less fish were away from the lake. Hence, the time between phyto- and zooplankton peaks depended only on the amount of fish being away from the lake, and not on temperature. The intensity of fish migration thereby had a major effect on plankton spring dynamics. These results significantly contribute to our understanding of the interplay between partial migration and trophic dynamics, and suggest that ongoing climate change may significantly affect such dynamics.

Evapotranspiration is an important component of hydrological cycle and a key input to hydrological models. Therefore, analysis of the spatiotemporal variation of potential evapotranspiration (PET) will help a better understanding of climate change and its effect on hydrological cycle and water resources. In this study, the Penman–Monteith method was used to estimate PET in the Wei River basin (WRB) in China based on daily data at 21 meteorological stations during 1959–2008. Spatial distribution and temporal trends of annual and seasonal PET were analysed by using the Spline interpolation method and the Mann–Kendall test method. Abrupt changes were detected by using the Pettitt test method. In order to explore the contribution of key meteorological variables to the variation of PET, the sensitivity coefficients method was employed in this study. The results showed that: (1) mean annual and seasonal PET in the WRB was generally decreasing from northeast to southwest. Summer and spring made the major contributions to the annual values; (2) annual and seasonal PET series in most part of the WRB exhibited increasing trends; (3) abrupt changes appeared in 1993 for annual and spring PET series for the entire basin, while summer value series was detected in the late 1970s. (4) Relative humidity was the most sensitive variable for PET in general for the WRB, followed by wind speed, air temperature and solar radiation. In the headwater and outlet of the WRB, relative humidity and air temperature were the most sensitive variables to PET, while relative humidity and wind speed were more influential in most part of the middle-lower region.

Species diversity can be lost through two different but potentially interacting extinction processes: demographic decline and speciation reversal through introgressive hybridization. To investigate the relative contribution of these processes, we analysed historical and contemporary data of replicate whitefish radiations from 17 pre-alpine European lakes and reconstructed changes in genetic species differentiation through time using historical samples. Here we provide evidence that species diversity evolved in response to ecological opportunity, and that eutrophication, by diminishing this opportunity, has driven extinctions through speciation reversal and demographic decline. Across the radiations, the magnitude of eutrophication explains the pattern of species loss and levels of genetic and functional distinctiveness among remaining species. We argue that extinction by speciation reversal may be more widespread than currently appreciated. Preventing such extinctions will require that conservation efforts not only target existing species but identify and protect the ecological and evolutionary processes that generate and maintain species.

Lakes are large sources of methane, held to be responsible for 18% of the radiative forcing, to the atmosphere. Periods of lake overturn (during fall/winter) are short and therefore difficult to capture with field campaigns but potentially one of the most important periods for methane emissions. We studied methane emissions using four different methods, including eddy covariance measurements, floating chambers, anchored funnels, and boundary model calculations. Whereas the first three methods agreed rather well, boundary model estimates were 5–30 times lower leading to a strong underestimation of methane fluxes from aquatic systems. These results show the importance of ebullition as the most important flux pathway and the need for <I>continuous</I> measurements with a large footprint covering also shallow parts of lakes. Although fluxes were high, on average 4 mmol m<SUP>–2</SUP> d<SUP>–1</SUP> during the overturn period, water column microbial methane oxidation removed 75% of the methane and only 25% of potential emissions were released to the atmosphere. Hence, this study illustrates second the importance of considering methane oxidation when estimating the flux of methane from lakes during overturn periods.

We investigated greenhouse gas emissions (CO<SUB>2</SUB>, CH<SUB>4</SUB>, and N<SUB>2</SUB>O) from reservoirs located across an altitude gradient in Switzerland. These are the first results of greenhouse gas emissions from reservoirs at high elevations in the Alps. Depth profiles were taken in 11 reservoirs located at different altitudes between the years 2003 and 2006. Diffusive trace gas emissions were calculated using surface gas concentrations, wind speeds and transfer velocities. Additionally, methane entering with the inflowing water and methane loss at the turbine was assessed for a subset of the reservoirs. All reservoirs were emitters of carbon dioxide and methane with an average of 970 ± 340 mg m<SUP>−2</SUP> day<SUP>−1</SUP> (results only from four lowland and one subalpine reservoir) and 0.20 ± 0.15 mg m<SUP>−2</SUP> day<SUP>−1</SUP>, respectively. One reservoir (Lake Wohlen) emitted methane at a much higher rate (1.8 ± 0.9 mg m<SUP>−2</SUP> day<SUP>−1</SUP>) than the other investigated reservoirs. There was no significant difference in methane emissions across the altitude gradient, but average dissolved methane concentrations decreased with increasing elevation. Only lowland reservoirs were sources for N<SUB>2</SUB>O (72 ± 22 μg m<SUP>−2</SUP> day<SUP>−1</SUP>), while the subalpine and alpine reservoirs were in equilibrium with atmospheric concentrations. These results indicate reservoirs from subalpine/alpine regions to be only minor contributors of greenhouse gases to the atmosphere compared to other reservoirs.

Longitudinal habitat connectivity within streams and rivers plays a key role for fish in freshwater systems because they migrate between different habitats used for spawning, feeding, or sheltering in alternating cycles during different life-history stages. The worldwide fragmentation of rivers due to human impacts has a negative effect on fish movement and dispersal. Many artificial barriers such as river bed sills and small weirs are nowadays replaced by block ramps in order to reestablish longitudinal connectivity for fish in rivers and streams. We studied the upstream passage of several fish species on eight different types of block ramps with slopes between 3.6 and 13.4 %. We conducted translocation experiments in the field based on mark-recapture and on the use of PIT-tags. Temporal movement patterns were observed by an instream antenna. Hydraulic and morphological characteristics of block ramps were measured and compared with fish passage efficiency. Our results clearly showed that upstream passage efficiency differs between fish species, size classes and block ramps. [...]<br /><br />Die Längsvernetzung in Fliessgewässern spielt für Fische eine entscheidende Rolle. Im Verlaufe ihres Lebenszyklus suchen Fische unterschiedliche Habitate auf, die sich zum Laichen, für die Nahrungsaufnahme oder als Zufluchtsort eignen. Die durch den Menschen verursachte, weltweite Fragmentierung der Gewässer hat negative Konsequenzen für die Wanderungen und Ausbreitung der Fische. Viele künstliche Wanderbarrieren wie Querbauwerke und Sohlschwellen werden heutzutage durch Blockrampen ersetzt, um das Gewässerlängskontinuum für Fische wiederherzustellen. Wir führten Erfolgskontrollen auf acht verschiedenen Blockrampentypen mit Gefällen zwischen 3.6 und 13.4 % durch. In einer Feldstudie wurden mittels Fang-Wiederfang-Versuchen und PIT-tags Translokationsexperimente durchgeführt. Zeitliche Bewegungsmuster wurden mit einer am Gewässer installierten Antenne verfolgt. Hydraulische und morphologische Blockrampenparameter wurden gemessen und mit dem Aufstiegserfolg der Fische verglichen. Unsere Resultate zeigen klar, dass der Aufstiegserfolg abhängig ist von der Fischart, der Grössenklasse der Fische und dem Blockrampentyp. [...]

Double diffusion enhances the vertical transport within a stratified water body by transforming gradual density gradients into staircases of convectively mixed layers separated by high-gradient and gravitationally stable interfaces. Those staircases can develop when two agents, which diffuse at different rates, contribute in opposing ways to the vertical density gradient. This study focuses on the diffusive regime of double diffusion, where the slower diffusing agent (here dissolved substances) is stabilizing. Estimating the vertical fluxes through double-diffusive staircases based on easily accessible parameters has been one goal of double diffusion research in the past. So far, flux laws are based on scaling arguments which are calibrated by empirical results from laboratory experiments and their validity in natural environments is questionable. Double-diffusive heat fluxes are of particular interest in the Arctic Ocean, where they control the heat exchange between a warm intrusion from the North Atlantic and the overlying sea ice. A more detailed understanding of double diffusion in natural environments is thus essential to test well-established theories. [...]<br /><br />Doppeldiffusion erhöht den vertikalen Transport in einem geschichteten Wasserkörper durch die Umwandlung von graduellen Dichtegradienten in Treppen aus konvektiv gemischten Schichten, die durch stabile Übergänge mit hohen Gradienten getrennt werden. Solche Treppen können sich entwickeln, wenn zwei Stoffe, die unterschiedlich schnell diffundieren, in gegensätzlicher Weise zum vertikalen Dichtegradienten beitragen. Diese Arbeit konzentriert sich auf das diffusive Regime doppeldiffusiver Konvektion, bei welchem der langsamer diffundierende Stoff stabilisierend wirkt. Die Abschätzung der vertikalen Flüsse durch doppeldiffusive Treppen anhand einfach zugänglicher Parameter war ein Ziel der Doppeldiffusionsforschung in der Vergangenheit. Bislang basieren Flussgesetze auf Skalierungsargumenten, die mit empirischen Resultaten aus Laborexperimenten kalibriert wurden und ihre Gültigkeit in natürlichen Umgebungen ist fraglich. Doppeldiffusive Wärmeflüsse im Arktischen Ozean sind von besonderem Interesse, weil sie dort den Wärmeaustausch zwischen einer warmen Intrusion aus dem Nordatlantik und dem darüber liegenden Eis kontrollieren. Ein besseres Verständnis von Doppeldiffusion in natürlichen Umgebungen ist darum notwendig um etablierte Theorien zu testen. [...]

Groundwater is an important drinking water resource in Switzerland and throughout the world. Despite the importance of groundwater, research on the impact of climate change on groundwater has attracted interest only recently. However, most of the research studies on this topic have focused on the potential impact of a changing climate on groundwater quantity rather than quality. The basic research task of this thesis was to determine past and future impacts of climatic forcing and climate change on some aspects of groundwater quality in Switzerland. To accomplish this task, time-series of historical records measured in the groundwater of several Swiss aquifers were analyzed. The best available data with regard to length and temporal resolution consisted of time-series of groundwater temperature and groundwater dissolved oxygen (DO) concentration in aquifers recharged by riverbank infiltration (RBF). Both groundwater temperature and DO concentration are important determinants of groundwater quality, in particular at RBF sites. The time-series were used to analyze the impact of the 1980s climate regime shift on groundwater temperature, to build models which enabled forecasts of groundwater temperature up to the end of the current century to be modeled, and to estimate the impact of a changing climate on groundwater DO concentration. [...]<br /><br />Grundwasser ist weltweit und insbesondere in der Schweiz eine wichtige Trinkwasserressource. Ungeachtet dessen wurde erst in letzter Zeit damit begonnen, mögliche Einflüsse des Klimawandels auf das Grundwasser wissenschaftlich zu untersuchen. Die meisten Studien haben dabei lediglich den Einfluss des Klimawandels auf die Verfügbarkeit des Grundwassers untersucht, während der Einfluss auf die Qualität nur marginal behandelt wurde. Das Hauptziel der vorliegenden Arbeit war es, vergangene und zukünftige, durch den Klimawandel verursachte Einflüsse auf die Grundwasserqualität in der Schweiz zu beurteilen. Zu diesem Zweck wurde auf historische Aufzeichnungen zurückgegriffen, die in verschiedenen Aquiferen der Schweiz gemacht wurden. Die bezüglich Länge und zeitlicher Auflösung besten Daten sind Zeitreihen von Temperatur und Sauerstoffkonzentration im Grundwasser von Aquiferen, die vornehmlich von Flüssen gespeist werden. Sowohl die Temperatur als auch die Sauerstoffkonzentration sind wichtige Kenngrössen für die Grundwasserqualität. Die Zeitreihen wurden verwendet, um den Einfluss des abrupten Klimasprungs Ende der 1980er-Jahre auf die Grundwassertemperatur nachzuweisen, um mit statistischen Modellen die Grundwassertemperatur bis zum Ende des Jahrhunderts vorherzusagen, sowie um den Einfluss der Klimaänderung auf die Sauerstoffkonzentration im Grundwasser abzuschätzen. [...]

To understand toxic biological effects of non-essential trace metals to organisms in the aqueous environment, one must be able to follow a series of complex metal interactions, both abiotic and biotic in nature, which ultimately lead to the internalization of a metal and its binding to sensitive cellular targets. We chose to work with periphyton, natural biofilm communities composed of algae, bacteria, fungi and protozoa held together in a matrix of extracellular polymeric substances (EPS). Periphyton is an important primary producer in freshwater ecosystems, which contribute to nutrient cycling and also accumulate both essential and non-essential trace metals, often reflecting dynamic fluctuations of metals in the overlying water. Using natural communities colonized with water from a small Swiss stream, the goal of this doctoral work was to understand the relationship between lead (Pb) accumulation and distribution in periphyton and the subsequent biological effects to overall community functions, as well as to understand intracellular Pb speciation upon internalization. [...]<br /><br />Um biologisch-toxische Auswirkungen von nicht-essentiellen Spurenmetallen auf Organismen (Lebewesen) in der aquatischen Umwelt zu verstehen, ist es wichtig komplexe abiotische und biotische Wechselwirkungen von Metallen nachzuvollziehen, die zur Aufnahme von Metallen und ihrer Bindung an sensitiven zellulären Targets (Zielobjekten) führen. Periphyton, eine Biofilmgemeinschaft, welche aus Algen, Bakterien, Pilzen und Protozoen in einer Matrix aus extrazellulärer polymerer Substanz (EPS) besteht, wurde für diese Untersuchung ausgewählt. Periphyton ist ein wichtiger Primärproduzent in Süsswasser-Ökosystemen, das zum Nährstoffkreislauf beiträgt und ebenfalls grosse Mengen essentielle und nichtessentielle Spurenmetalle akkumulieren kann, und dadurch oft Schwankungen der Metallkonzentrationen im darüberliegenden Wasser widerspiegelt. Das Ziel dieser Dissertation war es, den Zusammenhang zwischen der Akkumulation und der Verteilung von Blei (Pb) in Periphyton sowie die biologischen Auswirkungen anhand natürlicher Gemeinschaften zu verstehen. Dafür wurden Biofilme mit Wasser eines Schweizer Baches gezüchtet, um die intrazelluläre Pb-Speziierung durch die Aufnahme von Pb und die nachfolgenden Auswirkungen bis zu generellen Funktionen der Biolfilmgemeinschaft zu verstehen. [...]

Understanding the processes that shape biodiversity is a fundamental topic of ecology and important in the context of ecosystem services or disease prevention. Metacommunity ecology assesses the influence of local and spatial processes on the biodiversity of communities of interacting species connected by dispersal. However, metacommunity studies have primarily used simplified linear or lattice networks, which may not relate to more complex natural spatial networks, such as rivers, and dendritic river-like networks. Recent theoretical and empirical research suggests that the complex dendritic structure of river networks alters species dispersal, and subsequently biodiversity patterns. However, the temporal dynamics of biodiversity in dendritic networks and the relationship between different biodiversity measures are not yet fully understood. The overall aim of this thesis is to determine the importance of network structure, specifically dendritic networks found in river systems, on temporal diversity dynamics and whether observed spatial patterns of biodiversity are consistent across different measures and levels of biodiversity. [...]<br /><br />Das Verständnis von Prozessen, welche die Biodiversität formen, ist ein zentrales Thema der Ökologie und ist bedeutend für das Verständnis von Ökosystemprozessen oder für die Prävention von Epidemien. Die Ökologie der sogenannten “Metacommunity” befasst sich mit dem Einfluss von lokalen und räumlichen Prozessen auf die Biodiversität von Lebensgemeinschaften interagierender Arten, welche durch Ausbreitungsprozesse miteinander verknüpft sind. Bisher basierten Metacommunity-Studien primär auf vereinfachten linearen oder gitterartigen Netzwerken. Dies vernachlässigt allerdings komplexere räumlichen Netzwerken, wie beispielsweise dendritischen Netzwerken (wie zum Beispiel in Flüssen). Neue theoretische und empirische Forschungen weisen darauf hin, dass komplexere, dendritische Flussstrukturen die Verbreitung von Arten sowie Biodiversitätsmuster verändern. Weiter zeitliche Biodiversitätsdynamiken in dendritischen Netzwerken sowie die Beziehung verschiedener Biodiversitäts-Messzahlen noch nicht vollkommen verstanden. Das übergeordnete Ziel dieser Doktorarbeit ist die Wichtigkeit der Netzwerkstruktur, speziell dendritischer Netzwerke, und temporärer Diversitätsdynamiken zu verstehen. Weiter soll erforscht werden, ob beobachtete räumliche Biodiversitätsmuster konsistent sind zwischen verschiedenen Messzahlen und Ebenen, welche die Biodiversität beschreiben. [...]

Our centralized water supply systems are aging. Despite their success in reliably providing high quality drinking water, nowadays especially small utilities (e.g. less than 10’000 inhabitants supplied) are illprepared to face possible future challenges. The fragmented structure of the water supply sector leads to a lack of institutional, financial and personnel resources for professional management and planning of water supply systems. Current planning is furthermore challenged by insufficient knowledge and data about the prevailing water infrastructure condition and future rehabilitation demand. It usually ignores future dynamics and planning uncertainties, as well as alternatives to the perpetuation of the status quo. Infrastructure decision making is usually not transparent and only few stakeholders are included into the decision process. <BR/> This thesis presents an approach to overcome these shortcomings and support long-term water supply infrastructure planning under uncertainty in a multi-stakeholder context. Thereto, methods from multicriteria decision analysis (MCDA), strategic asset management (SAM), pipe failure modeling, and scenario planning were combined, adapted, and further developed. The suitability of the approach was validated in a case study in Switzerland. To improve the prediction of pipe service life in view of data scarcity, it was shown how the knowledge of experts can be quantitatively assessed and integrated into the calibration of pipe survival models by means of Bayesian inference. Similarly, knowledge gained from three mid-size to large Swiss water networks was used to improve calibration of a novel pipe failure model. It is demonstrated that this failure model is able to deal with the common data situation, and mitigate overestimation of the time to failure caused by the absence of data from already replaced pipes. The failure model was combined with a rehabilitation model to assess the performance of 18 rehabilitation strategies under four future scenarios for a small water utility. MCDA was used to compare these alternatives under different preferences concerning three objectives. The analysis revealed that the common strategy, purely reactive rehabilitation, is not recommendable in most cases and that annual replacement of 1–2 % of the network by condition might be a good strategy for the utility in question. <BR/> These findings were considered during the definition of alternatives for a second MCDA study aiming at identifying ‘good water supply infrastructure’ alternatives. Eleven alternatives and an objectives hierarchy consisting of 44 fundamental objectives and 30 attributes were developed together with stakeholders. The alternatives differ not only with regard to rehabilitation management, but also technical, managerial, and organizational aspects. The outcomes of all alternatives regarding these attributes were predicted under four future scenarios to account for uncertainties about the future development. The approach for the elicitation and modeling of preferences includes the imprecision of the stated preferences as well as uncertainties of preference parameters which were not elicited (the aggregation model, marginal value functions, risk attitude, and scaling factors). Preferences of ten selected stakeholders were then elicited and probability distributions of the ranking of alternatives based on these preferences were obtained. Despite differences in the individual rankings, a potential compromise solution could be proposed and ways for potential adaptation and improvement of other alternatives be indicated. In general, alternatives with good outcomes regarding groundwater protection, water quality, supply reliability, and realization of the rehabilitation demand received the highest ranks, as these were also among the most important objectives for the majority of the stakeholders. As operation and management do considerably contribute to the performance regarding the latter three objectives, the importance of a thorough infrastructure and rehabilitation management cannot be neglected. In view of the possible ranges of the outcomes, the objectives of ‘high social acceptance’ (e.g. disturbance by unnecessary road works, resources autonomy), and to some extent also ‘low costs’ were judged less important. <BR/> Multi-criteria decision analysis proved useful to support the long-term planning of water infrastructures under uncertainty and in a multi-stakeholder framework. The usual extrapolation of the status quo was overcome. Future dynamics and uncertainties could be incorporated by combining decision making and modeling with scenario planning, besides the quantitative consideration of uncertainties in making predictions, and evaluating the results. With the presented approaches for the modeling of pipe failures and rehabilitation, the methods and tools for the assessment of the current condition and future rehabilitation demand of small water networks despite a difficult data situation are now available.

The microbial cell is, in contrast to multicellular organisms, directly exposed to environmental stimuli and stresses. This means on one hand that dissolved nutrients can directly and quickly be taken up. On the other hand, this also implies that microbes are directly exposed to unfavourable conditions such as low nutrient concentrations, low or high pH and temperature, or UV light. In order to survive, the cells have to be able to adapt to these conditions. Unfavourable conditions, as well as all environmental changes that require physiological adaptations of the cell, i.e., in gene expression and cellular composition, can be regarded as a stress for the microbial cell. In <em>Escherichia coli </em>a wide range of responses to these stresses is governed by the alternative sigma factor σ^S. [...]<br /><br />Im Gegensatz zu multizellulären Organismen ist die mikrobielle Zelle Umwelteinflüssen und Stress direkt ausgesetzt. Einerseits heisst dies, dass gelöste Nährstoffe schnell direkt aufgenommen werden können, bedingt andererseits aber auch, dass Mikroorganismen ungünstigen Bedingungen wie niedrigen Nährstoffkonzentrationen, extremen pH-Werten und Temperaturen oder UV-Strahlung unmittelbar ausgesetzt sind. Um derartige Bedingungen zu überleben, müssen die Zellen in der Lage sein sich diesen anzupassen. Dabei müssen nicht nur ungünstige Umweltbedingungen als Stress für Mikroorganismen angesehen werden, sondern generell jede Veränderung der Umgebung, die eine physiologische Anpassung auf Ebene der Genexpression oder Zellzusammensetzung erfordert. In <em>Escherichia coli </em>wird eine Reihe von Antworten auf Umweltstress über den alternativen Sigma-Faktor σ^S gesteuert. [...]

In areas with mainly agricultural land use, the pollution of streams with herbicides remains a problem in many countries including Switzerland. The limit of a maximum concentration of 0.1 <em>µ</em>g L^-1 per single compound in surface waters, xed by Swiss law, can often not be achieved during the application periods. This leads to a threat for the aquatic ecosystems. Under Swiss (climatic) conditions, the main part of the herbicide pollution stems from diuse sources when herbicides are washed o the elds and transported to the streams. Field studies have shown that herbicide losses can be generated on a relatively small proportion of a catchment. These areas are called <em>critical source</em> or <em>contributing areas</em>. This spatial heterogeneity oers the possibility for ecient mitigation measures to reduce diuse pollution because actions on a small proportion of the area could signicantly reduce the herbicide input to the stream. [...]<br /><br />In Regionen mit mehrheitlich landwirtschaftlicher Landnutzung ist die Verschmutzung von Fliessgewässern mit Herbiziden auch in der Schweiz nach wie vor ein Problem. In den Applikationsperioden wird die gesetzlich festgelegte Maximalkonzentration von 0.1 <em>µ</em>g L^-1 pro Substanz häufig überschritten. Dies führt zu einer Gefährdung der aquatischen Ökosysteme.<br />Unter schweizer Bedingungen stammt die Gewässerbelastung mit Herbiziden hauptsächlich aus diffusen Quellen; d.h. die Herbizide werden während Regenereignissen von den Feldern weggewaschen und ins Gewässer transportiert. Frühere Felduntersuchungen haben gezeigt, dass der Grossteil der Herbizidbelastung von einem relativ kleinen Teil des Einzugsgebiets stammen kann. Diese Flächen werden <em>beitragende Flächen </em>oder<em> critical source areas </em>genannt. Diese räumliche Heterogenität ermöglicht effiziente Schutzmassnahmen, da Eingriffe auf einem kleinen Teil der Fläche die Herbizidbelastung im Gewässer signikant reduzieren können. [...]

The importance of ensuring good solid waste management is now well recognised at all levels: international, national and at community level as one essential element of sustainable development. With the United Nations declaration in Rio in 1992, “Rio Declaration on Environment and Development” and the Agenda 21 a commitment was made to address the issue and to foster environmentally sound, socially acceptable and economically feasible solid waste management. It is especially the waste managers at local government level in urban areas of low- and middle-income countries, who are struggling to improve the situation. Existing services and infrastructure are often dysfunctional or lacking. A large threat to public health and severe environmental pollution is the consequence and it is the poorest of the population that suffer most. Upgrading solid waste management to a long-term sustainable solution is not a simple task. It implies the integration and consideration of many aspects: technical and engineering issues, environmental impacts, public awareness and participation, sociocultural factors, financial and economic issues as well as institutional, legal and political concerns. To obtain an all-inclusive overview of the situation as well as the possibility to estimate the consequence of decisions and choices, a set of methods and tools is needed, which help ensure a structured and systematic way of thinking and a comprehensive guidance on data collection and analysis. This is where assessment methods for decision support enter into the picture. They can help: (a) to analyze the performance and its underlying causes as well as the impact of projects and activities; and (b) to evaluate and compare between improvement options based on criteria of choice. [...]<br /><br />L'importanza di garantire una buona gestione dei rifiuti solidi come un elemento essenziale per lo sviluppo sostenibile è ormai chiara a tutti i livelli: internazionale, nazionale e a livello comunitario. Con la dichiarazione delle Nazioni Unite di Rio del 1992, "Dichiarazione di Rio sull'ambiente e lo sviluppo", e l'Agenda 21 un impegno è stato preso per affrontare la questione e per promuovere una gestione dei rifiuti solidi ecologicamente corretta, socialmente accettabile ed economicamente fattibile. A lottare per migliorare la situazione sono in particolare i gestori dei rifiuti a livello di governo locale nelle aree urbane dei paesi a basso e medio reddito. Servizi esistenti e infrastrutture sono spesso disfunzionali o mancanti. La conseguenza è una minaccia per la salute pubblica e un grave inquinamento ambientale del quale soffre in particolare la popolazione più povera. Trasformare e migliorare la gestione dei rifiuti solidi in una soluzione sostenibile non è un compito semplice. Esso implica l'integrazione e la considerazione di molti aspetti: le questioni tecniche e ingegneristiche, l'impatto ambientale, la sensibilizzazione del pubblico e la sua partecipazione, i fattori socio-culturali, i problemi finanziari ed economici, e le questioni istituzionali, giuridiche e politiche. Per ottenere una visione d’insieme della situazione e per valutare le conseguenze di decisioni e scelte, è necessario un insieme di metodi e strumenti che aiutino a garantire un orientamento strutturato e sistematico e ad ottenere e analizzare dati specifici. Ecco dove i metodi di valutazione per il supporto delle decisioni entrano nel quadro. Essi possono contribuire a: (a) analizzare sia la performance e le cause sottostanti e l’impatto dei progetti e delle attività, e (b) valutare e confrontare le opzioni di miglioramento sulla base dei criteri di scelta. [...]

Traditionally, differences between individuals belonging to the same species are explained by differences in their genes and the environments they live in. In microbiological research, working with populations of genetically identical bacteria growing in homogeneous environments is standard procedure. A great amount of knowledge, on bacteria but also on general biological principles, has been gained by treating such populations as homogeneous samples and measuring traits on the population level. However, drawing conclusions from<br />such measurements is only valid under the implicit assumption that the measured trait is unimodally distributed in the population, and for a number of traits this assumption is wrong. Considering bacterial individuality generated by means other than genes and the environment – phenotypic heterogeneity – can lead to new insights in how bacterial communities work. This thesis is about the origins and functions of phenotypic heterogeneity. [...]<br /><br />Traditionell werden Unterschiede zwischen Individuen, die zur selben Art gehören, durch Unterschiede in ihren Genen und in der Umwelt in der sie leben erklärt. In der mikrobiologischen Forschung ist die Arbeit mit genetisch identischen bakteriellen Populationen, die in derselben Umwelt wachsen, der Standard. Eine grosse Menge an Wissen, über Bakterien aber auch über allgemeine biologische Prinzipien, ist gewonnen worden, indem man solche Populationen als homogene Proben behandelt und deren Eigenschaften auf Populationsebene gemessen hat. Allerdings ist es nur zulässig, Schlüsse aus solchen Messungen zu ziehen, wenn man implizit annimmt, dass die gemessene Eigenschaft in der untersuchten Population unimodal verteilt ist. Bei einigen Eigenschaften ist diese Annahme falsch. Wenn man bakterielle Individualität, die von anderen Mechanismen als den Genen und der Umwelt generiert wurde – phänotypische Heterogenität – in Betracht zieht, kann das zum Gewinn neuer Erkenntnisse darüber führen, wie bakterielle Gemeinschaften funktionieren. Diese Arbeit behandelt die Ursprünge und Funktionen von phänotypischer Heterogenität. [...]