Uncertainty in the distribution of hydraulic parameters leads to uncertainty in flow and reactive transport. Traditional stochastic analysis of solute transport in heterogeneous media has focused on the ensemble mean of conservative-tracer concentration. Studies in the past years have shown that the mean concentration often is associated with a high variance. Because the range of possible concentration values is bounded, a high variance implies high probability weights on the extreme values. In certain cases of mixing-controlled reactive transport, concentrations of conservative tracers, denoted mixing ratios, can be mapped to those of constituents that react with each other upon mixing. This facilitates mapping entire statistical distributions from mixing ratios to reactive-constituent concentrations. In perturbative approximations, only the mean and variance of the mixing-ratio distribution are used. We demonstrate that the second-order perturbative approximation leads to erroneous or even physically impossible estimates of mean reactive-constituent concentrations when the variance of the mixing ratio is high and the relationship between the mixing ratio and the reactive-constituent concentrations strongly deviates from a quadratic function. The latter might be the case in biokinetic reactions or in equilibrium reactions with small equilibrium constant in comparison to the range of reactive-constituent concentrations. When only the mean and variance of the mixing ratio is known, we recommend assuming a distribution that meets the known bounds of the mixing ratio, such as the beta distribution, and mapping the assumed distribution of the mixing ratio to the distributions of the reactive constituents.

Reservoirs have altered the flow regime of most rivers on the globe. To simulate the natural flow regime, experimental floods are being implemented on regulated rivers throughout the world to improve their ecological integrity. As a large-scale disturbance, the long-term sequential use of floods provides an excellent empirical approach to examine ecosystem regime shifts in rivers. This study evaluated the long-term effects of floods (15 floods over eight years) on a regulated river. We hypothesized that sequential floods over time would cause a regime shift in the ecosystem. The floods resulted in little change in the physicochemistry of the river, although particulate organic carbon and particulate phosphorus were lower after the floods. The floods eliminated moss cover on bed sediments within the first year of flooding and maintained low periphyton biomass and benthic organic matter after the third year of flooding. Organic matter in transport was reduced after the third year of flooding, although peaks were still observed during rain events due to tributary inputs and side slopes. The floods reduced macroinvertebrate richness and biomass after the first year of floods, but density was not reduced until the third year. The individual mass of invertebrates decreased by about one-half after the floods. Specific taxa displayed either a loss in abundance, or an increase in abundance, or an increase followed by a loss after the third year. The first three flood years were periods of nonequilibrium with coefficients of variation in all measured parameters increasing two to five times from those before the floods. Coefficients of variation decreased after the third year, although they were still higher than before the floods. Analysis of concordance using Kendall's <I>W</I> confirmed the temporal changes observed in macroinvertebrate assemblage structure. An assessment of individual flood effects showed that later floods had ∼30% less effect on macroinvertebrates than early floods of similar magnitude, suggesting that the new assemblage structure is more resilient to flood disturbance. We conclude that the floods caused an ecosystem regime shift that took three years to unfold. Additional long-term changes or shifts are expected as new taxa colonize the river from other sources.

Focus on actors - Initial experiences with system constellations in theory-based evaluations. In theory-based evaluations, program theories are used to illustrate and to analyze how program activities bring about outcomes. However, in order to gain a holistic understanding of a program, it is important to also consider the orientation and motivation of involved actors. In a research project, funded by the Austrian Central Bank's Anniversary Fund, system constellations - a tool applied in systemic consultation practice - were for the first time tested in the context of theory-based evaluations. System constellations were applied as a heuristic tool to rapidly give an insight into formal and informal relations between programs actors. The insights gained during constellations-work can offer a basis for more actor-centred program theories and evaluations. Program actor constellations facilitate the drafting of program theories and allow for more accurate statements about intended and unintended effects. Furthermore, they can be used as a basis for evaluation designs and as a creative research and communication tool. The article uses a case study to illustrate and reflect upon the initial experiences made with system constellations in theory-based evaluations.

Interfacial electron transfer has been shown to occur between sorbed Fe(II) and structural Fe(III) in Fe oxides, but it is unknown whether a similar reaction occurs between sorbed Fe(II) and Fe(III)-bearing clay minerals. Here, we used the isotopic specificity of ⁵⁷Fe Mössbauer spectroscopy to demonstrate electron transfer between sorbed Fe(II) and structural Fe(Ill) in an Fe-bearing smectite clay mineral (NAu-2, nontronite). Mössbauer spectra of NAu-2 reacted with aqueous ⁵⁶Fe(II) (which is invisible to ⁵⁷Fe Mössbauer spectroscopy) showed direct evidence for reduction of NAu-2 by sorbed Fe(II). Mössbauer spectra using aqueous ⁵⁷Fe(II) showed that sorbed Fe(II) is oxidized upon sorption to the clay and pXRD patterns indicate that the oxidation product is lepidocrocite. Spectra collected at different temperatures indicate that reduction of structural Fe(III) by sorbed Fe(II) induces electron delocalization in the clay structure. Our results also imply that interpretation of room temperature and 77 K Mössbauer spectra may significantly underestimate the amount of Fe(II) in Fe-bearing clays. These findings provide compelling evidence for abiotic reduction of Fe-bearing clay minerals by sorbed Fe(II), and require us to reframe our conceptual model for interpreting biological reduction of clay minerals, as well as contaminant reduction by reduced clays.

Water resources sustainability has the main contribution to the existence and durability of the farming systems and strongly depends on the cropping pattern practices A comprehensive cropping pattern planning takes in to account the high level of interrelation of the environmental, economic and social aspects of farming systems In order to assess the sustainability of water resources and determine an optimal pattern of cropping in a rural farming system, this paper introduces two ratios of "net return/water consumption" and "labor employment/water consumption" and attempts to simultaneously optimize them as the sustainability indicators To this purpose, a multi-objective fractional goal programming (MOFGP) procedure is considered as the main approach of the study to be accomplished by several other single and multi-objective linear and fractional programming models The results show that the FP models are more significant to contribute in assessing the sustainability indicators compared to the LP models, and the MOFGP solution is considered better, compared to the single objective FP solutions The results will be illustrated quantitatively.

Cement has been used extensively in nuclear and hazardous waste disposal for many years. Early attempts to incorporate constituents of high-level radioactive wastes during the clinkering stage had limitations due to the high processing temperatures employed and have now been superseded by low-temperature applications for less active and non-radioactive, industrial waste. Retention mechanisms for key heavy metals and metalloid ions in the cement matrix are reviewed and are shown to be irreversible in the majority of cases, provided a degree of physical durability is maintained. Quality control is often lacking, however, and there is an urgent need to establish performance standards and protocols analogous to those in the construction sector.

The feasibility of using anaerobic baffled reactor (ABR) as onsite wastewater treatment system was discussed. The ABR consisted of one sedimentation chamber and three up-flow chambers in series was experimented under different peak flow factors (PFF of 1 to 6), superficial gas velocities (between 0.6 and 3.1 cm/hr) and hydraulic retention times (HRT) (24, 36 and 48 hr). Residence time distribution (RTD) analyses were carried out to investigate the hydraulic characteristics of the ABR. It was found that the PFF resulted in hydraulic dead space. The dead space did not exceed 13% at PFF of 1, 2 and 4 while there was 2-fold increase (26%) at PFF of 6. Superficial gas velocities did not result in more (biological) dead space. The mixing pattern of ABR tended to be a completely-mixed reactor when PFF increased. Superficial gas velocities did not affect mixing pattern. The effects of PFF on mixing pattern could be minimized by higher HRT (48 hr). The tank-in-series (TIS) model (<i>N</i> = 4) was suitable to describe the hydraulic behaviour of the studied system. The HRT of 48 hr was able to maintain the mixing pattern under different flow patterns, introducing satisfactory hydraulic efficiency. Chemical oxygen demand (COD) and total suspended solids (TSS) removals under all flow patterns were achieved more than 85% and 90%, respectively. The standard deviation of effluent COD and TSS concentration did not exceed 15 mg/L.

Cities, as engines of economic growth and social development, require large quantities of natural resources to meet their inhabitants' economic and social needs. Good infrastructure and reliable service provision are key to sustaining cities' development. In this regard, they enhance investment opportunities and service access to vulnerable populations. In response to the lack of sanitation infrastructure, many governments, development agencies and NGOs usually implement programmes to provide latrines to poor and vulnerable populations. These programmes often do not link infrastructure provision and its necessary management requirements. As a result, the majority of 'latrine-based' cities do not have a reliable solution for emptying latrines, and for the transportation and treatment of faecal sludge and wastewater. When these infrastructures are available, they are disconnected from business opportunities which use resources such as water, nutrients or biosolids for their productive activities. This lingering failure in sanitation is putting a huge financial burden on municipalities who have to rely on permanent subsidies to operate and maintain infrastructures. The recent WHO guidelines on safe use of wastewater, excreta and greywater opens doors for reuse opportunities other than agricultural irrigation. It is leading towards a new paradigm. This paper discusses research needs to link urban sanitation management to cities' economic development agenda.

An important element in hydraulic modelling is the topography data of the riverbed and the floodplain area. The latter can be obtained directly from digital terrain models (DTM), but the measurement of the riverbed topography is not straightforward. Since in the aerial survey only the elevation of the water surface is recorded, information about the riverbed topography cannot be obtained from the DTM. Therefore a method for the integration of river topography data in a DTM was developed. While the DTM contains in most cases regularly spaced data points, the resolution of the cross section profiles is generally much higher in the lateral than in the longitudinal direction of the river. An algorithm was developed which combines lateral river profiles with a DTM to produce a grid that can be used for flow modelling. The cross section data are interpolated to the grid points of the DTM that are part of the channel by using a bilinear technique with bounding breaklines, which can be obtained from the river cross section profiles. Additionally the algorithm can be adapted so that only the submerged part of the riverbed is subject to interpolation. It preserves the original DTM in the exposed part of the gravel bars. The algorithm was applied to a restored reach of the river Thur in Switzerland. The corrected grid represents well the complex morphological features of the river such as gravel bars and widenings. The accuracy of the algorithm was tested by comparing the interpolated elevation of the exposed part of the gravel bar to measurements obtained from an aerial survey. The mean height difference is in the order of about 9 cm. Further the interpolated grid was used for a two dimensional flow simulation and the resulting water level was compared to the one recorded in the original DTM.

Previous work demonstrates that widely used fluoroquinolone antibacterial agents, including ciprofloxacin, are degraded by means of aqueous ultraviolet photolytic and titanium dioxide (TiO₂) photocatalytic (using both ultraviolet-A (UVA) and visible light (Vis) irradiation) treatment processes. In this study, we investigate the effects of photolytic and photocatalytic treatment processes on the antibacterial activity of ciprofloxacin solutions under controlled laboratory conditions. In agreement with earlier work, rates of ciprofloxacin degradation under comparable solution conditions (100 μM ciprofloxacin, 0 or 0.5 g/L TiO₂, pH 6, 25 °C) follow the trend UVA-TiO₂ > Vis-TiO₂ > UVA. Release of ammonia and fluoride ions is observed and a range of organic products have been identified with liquid chromatography-tandem mass spectrometry. However, the identified organic products all appear to retain the core quinolone structure, raising concerns about residual antibacterial potency of the treated solutions. Quantitative microbiological assays with a reference <i>Escherichia coli</i> strain indicate that the antimicrobial potency of ciprofloxacin solutions track closely with the undegraded ciprofloxacin concentration during photolytic or photocatalytic reactions. Quantitative analysis shows that for each mole of ciprofloxacin degraded, the antibacterial potency of irradiated solutions decreases by approximately one "mole" of activity relative to that of the untreated ciprofloxacin solution. This in turn indicates that the ciprofloxacin photo(cata)lytic transformation products retain negligible antibacterial activity relative to the parent compound. The energy demands for achieving one order of magnitude reduction in antibacterial activity within the experimental system are estimated to be 175 J/cm² (UVA-only), 29 J/cm² (Vis-TiO₂), and 20 J/cm² (UVA-TiO₂), which indicates that the UVA-TiO₂ photocatalysis is the most energy efficient process for achieving ciprofloxacin inactivation under laboratory conditions.

The field of microbial ecology has grown tremendously with the advent of novel molecular techniques, allowing the study of uncultured microbes in the environment, and producing a paradigm shift: now, rather than using bacteria cultures for evaluating cell-specific questions, researchers use RNA and DNA techniques to examine more broad-based ecological and evolutionary constructs such as biogeography and the long-debated biological species concept. Recent work has begun to relate bacteria functional genes to ecosystem processes and functioning, thereby enabling a better understanding of the interactive role of bacteria in different and often-changing environments. The field continues to mature and will most likely make substantial contributions in the future with additional efforts that include metagenomics and genomics. Here we review progress in the application of molecular techniques to study microbial communities in freshwater environments.

Accurate knowledge of freshwater availability is indispensable for water resources management at regional or national level. This information, however, has historically been very difficult to obtain because of lack of data, difficulties in the aggregation of spatial information, and problems in the quantification of distributed hydrological processes. The currently available estimates of freshwater availability by a few large international organizations such as FAO and UNESCO are often not sufficient as they only provide aggregated rough quantities of river discharge and groundwater recharge (blue water) at a national level and on a yearly basis. This paper aims to provide a procedure to improve the estimations of freshwater availability at subbasin level and monthly intervals. Applying the distributed hydrological model "Soil and Water Assessment Tool" (SWAT), the freshwater availability is quantified for a 4-million km<SUP>2</SUP> area covering some 18 countries in West Africa. The procedure includes model calibration and validation based on measured river discharges, and quantification of the uncertainty in model outputs using "Sequential Uncertainty Fitting Algorithm" (SUFI-2) The aggregated results for 11 countries are compared with two other studies. It was seen that for most countries, the estimates from the other two studies fall within our calculated prediction uncertainty ranges. The uncertainties are, in general, within reasonable ranges but larger in subbasins containing features such as dams and wetlands, or subbasins with inadequate climate or landuse information. As the modelling procedure in this study proved quite successful, its application for quantification of freshwater availability at a global scale is already underway. There are, however, two limitations in the West African model: (1) not all the components of the water balance model such as soil moisture or deep aquifer recharge could be directly calibrated because of lack of data and (2) the full capabilities of the SWAT model could not be realized because of the lack of local water and agricultural management information.

We propose and evaluate a mode-of-action based test battery of low-complexity and <I>in-vitro</I> bioassays that can be used as a routine monitoring tool for sewage treatment efficiency and water quality assessment. The test battery comprises five bioassays covering five different modes of toxic action. The bioluminescence inhibition test with <I>Vibrio fischeri</I> and a growth rate inhibition test with the green algae <I>Pseudokirchneriella subcapitata</I> are measures of non-specific integrative effects. A second endpoint in the algae test, the specific inhibition of the efficiency of photosynthesis, gives an account of the presence of herbicides. An enzymatic assay covers an important aspect of insecticidal activity, the inhibition of the acetylcholine esterase activity. Estrogenic effects are assessed with the yeast estrogen screen (YES) and genotoxicity with the umuC test. Three field studies, each lasting six to seven consecutive days, were undertaken at a sewage treatment plant (STP) in Switzerland. Samples were collected in summer and late autumn, under dry and rainy conditions. None of the bioassays gave positive results with raw water in whole effluent toxicity testing. Therefore, water samples from various sites during wastewater treatment and from surface water were enriched with solid-phase extraction. The focus was on non-volatile compounds of average to moderate hydrophobicity, a range that includes most pesticides, biocides and pharmaceuticals. Various polar solid phases were evaluated for their extraction efficiency, disturbance by matrix components and overall performance. We finally selected a mixture of a polymeric sorbent and a C18-sorbent, Lichrolut EN and RP-18 or, alternatively, Empore™ SDB-RPS disks. All bioassays gave clear and robust responses with the SPE extracts. With the bioassay data the treatment efficiency of the STP can be assessed with respect to different modes of toxic action and accordingly different groups of micropollutants. Furthermore, the data allowed for a comparison between the effluent and the receiving river. In all bioassays the primary effluent had a strong effect and this effect was reduced after passing the STP. Treatment efficiency was high (typically over 90%) but varied from bioassay to bioassay, which is expected because each bioassay detects different types of micropollutants and therefore we cannot expect a common answer.

The toxic equivalency concept is a widely applied method to express the toxicity of complex mixtures of compounds that act <I>via</I> receptor-mediated mechanisms such as induction of the arylhydrocarbon or estrogen receptors. Here we propose to extend this concept to baseline toxicity, using the bioluminescence inhibition test with <I>Vibrio fischeri</I>, and an integrative ecotoxicity endpoint, algal growth rate inhibition. Both bioassays were validated by comparison with literature data and quantitative structure-activity relationships (QSARs) for baseline toxicity were developed for all endpoints. The novel combined algae test, with <I>Pseudokirchneriella subcapitata</I>, allows for the simultaneous evaluation of specific inhibition of photosynthesis and growth rate. The contributions of specific inhibition of photosynthesis and non-specific toxicity could be differentiated by comparing the time and endpoint pattern. Photosynthesis efficiency, measured with the saturation pulse method after 2 h of incubation, served as indicator of specific inhibition of photosynthesis by photosystem II inhibitors. Diuron equivalents were defined as toxicity equivalents for this effect. The endpoint of growth rate over 24 h served to derive baseline toxicity equivalent concentrations (baseline-TEQ). By performing binary mixture experiments with reference compounds and complex environmental samples from a sewage treatment plant and a river, the TEQ concept was validated. The proposed method allows for easier interpretation and communication of effect-based water quality monitoring data and provides a basis for comparative analysis with chemical analytical monitoring.

In this study, several emerging compounds of concern in waste water are identified and discussed in relation to data available on their sources and mass flows in urban waters. In most western European situations, the highest contributions to the mass flow of xenobiotics to the urban water cycle stems from household and services applications (e.g. personal care compounds, pharmaceuticals, steroid hormones, flame retardants, fluorinated detergents etc.) as well as building and constructing environments (e.g. flame retardants, plasticizers, UV-blockers and biocides). The contribution from industrial point sources such as incineration industries e.g. coal, tar, steel and gas production (such as PAHs, PCBs, dioxins, etc.) and chemical industries are decreasing in relevance in terms of input and are hence currently of more local relevance only. In relation to identified compounds, this paper considers current data availability and its use in a range of management strategies for the mitigation or controlling of xenobiotics 'at source'. However it also identifies major knowledge gaps relating to the behaviour and fate of organic pollutants in various sectors of the urban water cycle including stormwater management, bank- and soil infiltration as well as underground and soil passage of polluted waters. It is also discussing the major sources of a range of current day urban pollutants. The paper considers the sources of emerging pollutants in a qualitative way.

The natural flow regime of many rivers on the globe has been altered by regulation, strongly influencing river morphology and aquatic biota. The incorporation of regime-based criteria such as flow and temperature regimes in restoration plans is an important step in river management. This paper summarizes the effects of a long-term flood program (15 floods over 8 years) on the river Spöl, Swiss National Park, on water physico-chemistry and river biota (periphyton, macroinvertebrates and fish). Due to hypolimnetic release, the floods had little impact on physical and chemical parameters. Periphyton biomass was reduced by the early floods and remained at low levels throughout the study period. Macroinvertebrate taxon richness, biomass and density were also significantly reduced and the macroinverrebrate assemblage shifted towards more disturbance-resistant taxa. The quality of fish habitat, especially for spawning, was noticeably improved by the floods. Further analysis suggested that the response of biota to floods of similar magnitude have changed over the study period in concert with the compositional shift in biotic assemblages.

We studied the long-term acclimatization of freshwater periphyton communities exposed to low and high ultraviolet radiation (UVR) intensities that simulate UVR doses received by lowland and high-mountain streams of central Europe. To assess changes induced by UVR, we compared the community structure (species and biomass), function (photosynthetic yield), and tolerance to UVR and cadmium of periphyton growing in microcosms (artificial channels). On the basis of the rationale behind the pollution-induced community tolerance concept, we expected that an increase in UVR tolerance would be through the replacement of more sensitive taxa by more tolerant taxa. After 38 d of exposure, periphyton in the high-UVR treatment was dominated by Cyanobacteria, whereas diatoms dominated periphyton in the low-UVR treatment. Concomitantly, the high-UVR community increased its tolerance to UVR and showed cotolerance to cadmium (Cd). Structural changes contributing to this increased tolerance included an increase in UVR-absorbing compounds, and the formation of cell aggregates that increased self shading. Induction of antioxidant enzymes after UVR and Cd exposure might be involved as defense mechanisms against oxidative stress. These changes reduced the exposure and effects of UVR, resulting in the protection of photosynthesis (high-UVR photosynthetic yield was unaffected). A fivefold reduction in chlorophyll a in the high-UVR treatment suggested that acclimatization had high metabolic costs. Additional experiments showed that even though biomass accrual offered some protection against UVR and Cd, the community changes experienced by the high-UVR community contributed the most to UVR tolerance. Periphyton exposed to high UVR may experience simultaneous positive (tolerance to UVR and cotolerance to Cd) and negative effects (biomass reduction can increase accessibility by toxicants).

Le régime hydrologique naturel de la grande majorité des rivières du globe a été modifié par une régulation artificielle, qui a profondément affecté la morphologie fluviale et la vie aquatique. L’intégration de critères hydrologiques comme le débit et la température dans les programmes de restauration constitue une étape importante pour la gestion de rivière. Cet article synthétise les observations, en terme de qualité physicochimique de l’eau et de biocénose aquatique, des effets d’une programmation de crues sur le long terme (15 crues artificielles en huit ans) sur la rivière Spöl, dans le Parc National Suisse. Du fait des lâchers d’eau hypolimnétiques (issues des eaux profondes), ces crues ont peu d’impact sur les paramètres physiques et chimiques. La biomasse du périphyton a été réduite par les premières crues, puis s’est maintenue à des niveaux faibles pendant toute la période étudiée. La richesse spécifique, la biomasse et la densité de macro-invertébrés ont aussi été significativement réduites, et l’association de macroinvertébrés a évolué vers des taxons plus résistants aux perturbations. La qualité des habitats piscicoles, en particulier pour les zones de frai, a été sensiblement améliorée par les inondations. Une analyse plus approfondie a montré que la réponse de la biocénose à des crues d’ampleur similaire a changé pendant la période d’étude en parallèle avec la modification de la composition des associations biotiques.

Bangladesh has a unique hydro-geological setting and deltaic floodplain which is jointly formed by the deposition of the Ganges (Padma), Brahmaputra (Jamuna) and Meghna River. The physical characteristics of the geographic location, river morphology and the monsoon climate render Bangladesh highly vulnerable to natural disasters, primarily, floods and cyclones. River flooding has exerted a great impact on the culture and socioeconomic activities. The char people and their settlements in the Padma River channel are under threat due to floods and associated river bank erosion. The excess of water happens during the monsoon season because of widespread flooding that damages char-land settlements, agricultural crops, infrastructure and communication networks. Purba Khas Bandarkhola Mouza of Char-Janajat is largely affected by annual floods, and as a result the char people are displaced frequently from one place to another within and/or outside the char. The dwellers can return to the native char when new land emerges in the river channel after floods. This study has revealed that the displacement of char settlement takes place in almost every 3–5a at Purba Khas Bandarkhola Mouza of Char-Janajat. Our findings shed light on the char flood disaster management and social adaptation plan for settlement development of char livelihood in the Padma River basin in the Ganges delta of Bangladesh.

Quantitative Biodegradability-Structure Relationships (QSBRs) are valuable tools for estimating pesticide half-lives in soil. Advance in QSBR modeling is based on several prerequisites: (1) separation of (bio)degradation from formation of non-extractable soil residues (NER), (2) degradation data from a homogeneous soil source, (3) robust predictor selection, (4) proper control of model complexity and (5) validation of model generalization performance on data external to model construction. This study addresses (1) to (5) in two steps.<br /> In step one, rst order rate constants of both primary degradation and NER formation were calculated from inverse model optimization by Genetic Algorithms, based on 87 Speyer 2.2 soil degradation data sets. Degradation was found to be faster than NER formation for most of the compounds, although both processes were correlated.<br /> In a second step, variation in degradation rate constants was modeled by LASSO shrinkage regression and, in addition, by a novel robust ltering technique combined with forward selection, termed Recursive Bootstrap Subsampling (RBS). RBS and shrinkage regression were applied to four predictor sets of increasing complexity and validated by (a) internal cross-validation (CV), (b) external CV and (c) external CV under proper control of model complexity. As a result, (a) overestimated generalization performance for all models and predictor sets, whereas (b) underestimated the performance achievable with a given data set. (c), on the other hand, gave more reasonable estimates. Moreover, shrinkage regression could outperform RBS under setting (b). However, when (c) control of model complexity was assured and the number p of predictors outnumbered that of the samples n (<em>n</em> &lt;&lt; <em>p</em> problem), RBS outperformed shrinkage regression. Therefore, only RBS was utilized to assess the importance of molecular and non-molecular predictors for explaining variation in degradation rates. Of a total of 670 candidate predictors, only few were important. The most relevant ones were: 3 collinear fragments containing sulfur, ester functionalities, 3 collinear N-heteroaromatic moeities, nitrogen with double or triple bonds, a methyl and a methylene descriptor, double bonded oxygen and water-organic carbon partitioning constants.<br /> It is concluded that a combination of robust predictor selection, external validation and control of model complexity other than internal CV is essential for reliable QSBR modeling.

The recovery of nutrients from urine for reuse in agriculture curbs the need to buy expensive commercial fertilizers and prevents eutrophication of water bodies through uncontrolled sewage discharge. However, direct field application of liquid urine is limited due to storage, transportation, and socio-cultural constraints. The precipitation of struvite (MgNH₄PO₄-6H₂O) is an option to trap almost all the phosphorus (P) from urine as a solid, storable and easily applicable fertilizer. The objective of the study at hand was to assess aquaculture in the context of Nepal as a possibility to recover the remaining nutrients from struvite production effluent– mainly nitrogen (N) and potassium (K) – or from urine itself, thereby producing protein-rich plant biomass that can be used as animal feed or green manure. [...]<br /><br /> Die Rückgewinnung von Nährstoffen aus Urin zur Wiederverwendung in der Landwirtschaft senkt den Bedarf an teuren chemischen Düngern und wirkt der Eutrophierung von Gewässern durch unkontrollierte Abwassereinleitung entgegen. Lagerungs- und Transportschwierigkeiten sowie soziokulturelle Faktoren schränken jedoch die direkte Verwendung von flüssigem Urin auf den Feldern ein. Die Fällung von Struvit (MgNH₄PO₄-6H₂O) ermöglicht es, einen Grossteil des Phosphors (P) aus Urin als festen, lagerfähigen und einfach auszubringenden Dünger einzufangen. Ziel der vorliegenden Arbeit war eine Eignungsabklärung von Aquakultur in Nepal zur Rückgewinnung der verbleibenden Nährstoffe – v.a. Stickstoff (N) und Kalium (K) – aus Struvitproduktionsabfluss (fortan „Effluent“ genannt) und aus Urin selber für die Produktion von Pflanzenbiomasse als proteinreiches Tierfutter oder Gründüngung.[...]

Der Anammox-Prozess (anaerobe Ammoniumoxidierung) ist eine Möglichkeit Stickstoff biologisch abzubauen. Anammox hat im Gegensatz zu Nitrifikation/Denitrifikation den Vorteil, dass kein leicht abbaubarer Kohlenstoff verbraucht wird. Die Anwendung dieses Prozesses in dezentralen Urinbehandlungsanlagen wird an der Eawag in Dübendorf seit 2008 in einer Pilotanlage getestet. Die Messungen mit einer Sauerstoff-, einer Leitfähigkeits- und einer pHSonde haben gezeigt, dass die Signale während eines Zyklus einen charakteristischen Verlauf aufweisen.<br /> Das führte zur Vermutung, dass sich der Prozess anhand dieser drei Sondensignale überwachen lässt. Das Ziel war die Untersuchung folgender Frage: Können anhand einer Kombination der drei Parameter Sauerstoff, pH-Wert und Leitfähigkeit biologische Prozesse identifiziert und quantifiziert werden?<br /> In der vorliegenden Arbeit werden folgende vier Hauptaufgaben vorgestellt:<br /> • Tabelle zur quantitativen Bewertung der Sondensignale<br /> • Quantifizierung des Stickstoffabbaus mittels der Leitfähigkeit<br /> • Modellierung der Leitfähigkeit<br /> • Unterscheidung von Anammox und heterotropher Denitrifikation anhand des pH-Werts und der Leitfähigkeit.<br /> Die <em>Tabelle zur qualitativen Bewertung der Sondensignale</em> ist ein nützliches Mittel um rasch eine Aussage zum Zustand des Systems machen zu können. In der zur Verfügung stehenden Zeit, konnten nicht alle Störfälle beurteilt werden. Sie müssen noch modelliert werden, damit man die Tabelle vervollständigen kann.<br /> Die <em>Quantifizierung des Stickstoffabbaus</em> durch die Leitfähigkeitsabnahme ist ein interessanter Ansatz. Bedingt durch einige Parameter - das Strippen von CO2 und der Abbau von organischen Stoffen zu Beginn des Zyklus - ist die Unsicherheit der Bestimmung des Stickstoffabbaus derzeit noch zu gross, um eine zuverlässige Aussage machen zu können. Es sind weitere Untersuchungen nötig um festlegen zu können, wie diese Parameter miteinzubeziehen sind.<br /> Die <em>Leitfähigkeit </em>lässt sich mit der allgemeinen Formel gut berechnen. Werden bei der Berechnung alle gemessenen Ionen miteinbezogen, wird die Leitfähigkeit durch das Ergebnis der Modelle deutlich überschätzt. Ein besseres Resultat wird erzielt, wenn man die Leitfähigkeit mit der Aktivität modelliert.<br /> Eine <em>Unterscheidung von heterotropher Denitrifikation und Anammox</em> ist zurzeit (noch) nicht möglich. Bei beiden Prozessen nimmt der pH-Wert zu und die Leitfähigkeit nimmt ab. Die modellierten Veränderungen sind so gering, dass die Sondensignale unter Einbezug der Messunsicherheit schwierig zu interpretieren sind. Zudem ist die Frage des Einflusses von Puffern noch nicht geklärt.<br /> Zusammenfassend ist zu sagen, dass die Onlineüberwachung mit Sonden, die die beschriebenen drei Schlüsselsignale ermitteln, ein guter Ansatz ist. Dieses Vorgehen ermöglicht eine Prozessüberwachung ohne grossen Messaufwand. Der pH-Wert wird bereits heute für die Steuerung der Zykluslänge verwendet. Die Sauerstoffkonzentration gibt Auskunft über die Funktion der Belüftung und die Messdaten der Leitfähigkeit können evtl. in Zukunft für die Quantifizierung des Stickstoffabbaus verwendet werden.

Aphids occur on almost 300 different crops and approximately a hundred aphid species are responsible for yield loss and economic damages in millions. Therefore, it is not surprising that aphids are seen as agriculture pest. Thus, intense research was done on aphid biology like the sequencing of the pea aphid genome, and in biological control of aphids which still is an important research topic. Among the most important enemies of aphids are parasitoid wasps, which lay their eggs into aphids. The wasp larva develops inside the aphid and in the last larval stage kills its host and makes a cocoon also called a mummy. However, the parasitic success of the wasps varies dramatically between different aphid clones. Further investigations have shown that the difference susceptibility to wasps is due to presence or absence of so called bacterial endosymbionts, especially <em>Hamiltonella defensa</em> and one strain of <em>Regiella insecticola</em>. These facultative endosymbionts increases the resistance of aphids against parasitoids and are vertically inherited from mother to offspring, but phylogenetic evidence indicates that horizontal endosymbiont transfer can occur as well. Not much is known about mechanisms of horizontal endosymbiont transfer. Therefore, in this study, I test four possible, natural ways of horizontal endosymbiont transfer: 1) Do parasitic mites of the family Trombidiidae act as horizontal vectors for endosymbiont transfer by sucking hemolymph of infected and uninfected aphids? 2) Are parasitoidic wasps able to act as vectors for horizontal transmission of aphid secondary endosymbionts by depositing their eggs first in endosymbiont-positive aphids and then in endosymbiont-negative aphids? 3) Are aphid parasitoids able to spread secondary endosymbionts when hatching from endosymbiont-positive aphids and subsequently stinging endosymbiont-negative aphids? 4) Finally, I’m asking whether horizontal transmission of secondary endosymbionts by oral uptake is also observed under realistic conditions? My experiments could show that in one of these ways, horizontal endosymbiont transfer occurs namely when an uninfected aphid got stung by a wasp which previously stung an endosymbiont-infected aphid. In 3.3% of those events (95% Wilson score interval 1.3-7.3%) the aphid survived the attack, got infected with the endosymbiont and inherited it to its offspring. Over this route it was possible to transfer <em>H. defensa</em> as well <em>R. insecticola</em>. In all other experiments no horizontal transmission could be observed. My study reveals a new natural route during parthenogenetic life cycle (spring to autumn) of the aphids, in which horizontal endosymbiont transfer occurs at a nameable rate. Similar to a mutation, this is equivalent to a spontaneous acquisition of an inheritable (maternal heredity), ecologically relevant trait and, when selected for it, can lead to a fast adaptation through parasitoids.<br /><br /> Blattläuse kommen auf fast 300 Nutzpflanzen vor, wobei rund 100 Blattlausarten für riesige Ernteausfälle und demzufolge für Schäden in Millionenhöhe verantwortlich sind. Deshalb verwundert es kaum, dass Blattläuse hauptsächlich als Schädlinge betrachtet werden und die Schädlingsbekämpfung auch in der Forschung ein wichtiges Thema ist. Von speziellem Interesse für die biologische Schädlingsbekämpfung sind die natürlichen Feinde der Blattläuse. Zu den wichtigsten Nützlingen zählen parasitoide Schlupfwespen, welche Eier in Blattläuse legen. Aus diesen entwickeln sich Wespenlarven, die wiederum während des Verpuppens ihren Wirt, die Blattlaus, töten. Allerdings unterscheidet sich der Parasitierungserfolg von Wespen dramatisch zwischen verschiedenen Blattlauspopulationen. Weiterführende Untersuchungen haben gezeigt, dass diese Unterschiede durch den Besitz bzw. das Fehlen endosymbiotischer Bakterien, insbesondere durch <em>Hamiltonella defensa</em> und einem Stamm von <em>Regiella insecticola</em>, erklärbar sind. Diese fakultativen Endosymbionten erhöhen die Resistenz der Blattläuse gegen Parasitoide und werden vertikal von der Mutter an ihre Nachkommen vererbt, Phylogenetische Hinweise deuten jedoch darauf hin, dass gelegentlich auch ein horizontaler Endosymbionten-Transfer stattfinden kann. Die Wege der horizontalen Übertragung sind jedoch noch weitgehend ungeklärt. In dieser Arbeit teste ich deshalb vier mögliche, natürliche Arten von horizontalem Endosymbionten-Transfer: 1) Können parasitische Milben der Familie Trombidiidae als horizontaler Vektor agieren, indem sie zuerst bei Blattläusen mit Endosymbiont und danach bei Blattläusen ohne Endosymbiont saugen? 2) Können parasitoide Wespen als horizontaler Vektor agieren, indem sie zuerst Eier in Läuse mit Endosymbiont und danach Eier in Läuse ohne Endosymbiont legen? 3) Können parasitoide Wespen, die frisch aus einer Endosymbiont-infizierten Laus geschlüpft sind, die Endosymbionten verbreiten, indem sie Läuse ohne Endosymbionten stechen? 4) Reicht es, wenn Blattläuse ohne Endosymbiont in einer Kolonie von Blattläusen mit Endosymbiont leben, um den Endosymbionten oral aufzunehmen? Meine Versuche zeigten, dass einer dieser Wege tatsächlich zu einer horizontalen Übertragung von Endosymbionten führen kann, nämlich wenn eine uninfizierte Blattlaus von einer Wespe gestochen wird, die zuvor eine Blattlaus mit Endosymbionten gestochen hat. In 3.3% dieser Fälle (95% Wilson score interval 1.3 - 7.3 %) überlebten die Blattläuse die Attacke, erwarben dabei den Endosymbionten und gaben ihn an ihre Nachkommen weiter. Auf diesem Wege konnten sowohl <em>H. defensa</em> als auch <em>R. insecticola</em> übertragen werden. In allen anderen Versuchen wurde keine horizontal Übertragung fakultativer Endosymbionten beobachtet. Meine Studie zeigt also eine neue natürliche Route, über welche während der parthenogenetischen Lebensphase der Blattläuse (Frühjahr bis Herbst) Endosymbionten mit einer nennenswerten Rate horizontal übertragen werden können. Ähnlich einer Mutation entspricht dies dem spontanen Erwerb eines erblichen (maternale Übertragung), ökologisch relevanten Merkmals, was eine rasche Anpassung bei Selektion durch Parasitoide erlaubt.

Genetic and phenotypic variance/covariance matrices offer a good method to study multivariate divergence between populations and the effects of evolutionary forces on correlated traits. Even thought computer simulation based studies suggest that evolutionary forces can change the properties of such matrices considerably, empirical studies which implement this method in natural systems are very scarce. As for example gene flow has been shown to be able to change the eccentricity of such matrices, which again constrains the evolutionary trajectory and potential of a population. In this study we use a closely related species pair of Lake Victoria cichlids (<em>Pundamilia pundamilia and Pundamilia nyererei</em>), which shows different amount of interspecific gene flow at four different islands in the Mwanza gulf, Lake Victoria. We show that the eccentricity of the phenotypic variance/covariance matrix is affected by the amount of gene flow. For<em> P. pundamilia</em> we were able to show a significant effect whereas for <em>P. nyererei</em> the results were less clear. Further studies are needed to make good predictions about the general importance of the effect of gene flow on the structure of G and P matrices and to come up with good models which can predict the influence of different evolutionary forces under specific circumstances.

Die ARA Foce Maggia und ARA Foce Ticino im Kanton Tessin reinigen das Abwasser von rund 110‘000 Einwohnergleichwerten und eliminieren die Schmutzstoffe CSB zu 92%, Stickstoff zu 27% und Phosphor zu 88%. Beide Anlagen werden ohne die Stufen Nitrifikation/Denitrifikation, aber gemäss dem Verfahren einer biologischen Phosphorelimination (Bio-P) betrieben. Diese scheint im heutigen Betrieb jedoch nur beschränkt stattzufinden, so dass eine erhebliche Menge Fällmittel zum Einsatz kommen, welche erhöhte Betriebskosten verursachen.<br /> Eine Mess- und Versuchskampagne sowie die Implementierung der Anlagen in der Software ASIM quantifizieren die Prozesse der Phosphorelimination. So zeigt sich, dass auf der ARA Foce Ticino Phosphor nur zu 20% über den Bio-P-Prozess eliminiert wird. Der Fällung wird 40% der Reinigungsleistung zugeschrieben.<br /> Einer der Hauptstörfaktoren des Bio-P wird in den (<em>1</em>) Fällmitteln eruiert. Die im anaeroben Teil des Belebungsbeckens rückgelösten Polyphosphate werden von Fällmitteln gebunden und stehen in der belüfteten Zone den PAO nicht mehr zur Verfügung, worauf diese nicht optimal einwachsen können. Die Konkurrenzsituation von Fällmitteln und Bio-P stellt eine gegenseitige Ursache-Wirkung-Beziehung dar: Ein schwaches Bio-P muss durch Fällmittel kompensiert werden; die Fällmittel limitieren jedoch wiederum das Bio-P. Für die suboptimale Phosphorelimination werden zudem weitere Ursachen identifiziert: (<em>2</em>) Denitrifikation im Nachklärbecken und damit erhöhte TSS-Konzentration im ARA Ablauf, (<em>3</em>) geringes Schlammalter, (<em>4</em>) eine bei Zeiten Probleme bereitende Trocknungsanlage, (<em>5</em>) erhöhte Phosphatrückbelastung durch Rücklösungsprozesse während der Überschussschlammstapelung mit anschliessender Eindickung, (<em>6</em>) Beeinträchtigung der biologischen Prozesse durch die hohe Ammoniumrückbelastung mit dem Faulwasser.<br /> Aufgrund der Analyse der Ursachen für ein gestörtes Auftreten der biologischen Phosphorelimination werden diverse Optimierungsvorschläge erarbeitet. Diese lassen sich grob in drei Kategorien einteilen:<br /><em>Nitrifikation/Denitrifikation</em>: Mit der Einführung dieser Stufen lässt sich die Anlage mit höheren TS-Konzentrationen und Schlammalter fahren. Zudem kann mit einer internen Rezirkulation eine effektiv anaerobe Zone mit Selektorwirkung geschaffen werden. Diese Massnahme bedarf eines Volumenausbaus der Belebungsbecken. Die Einführung des Anammox-Verfahrens zur separaten Faulwasserbehandlung unterstützt diese Massnahme. Zudem könnte der Einbau von Trennwänden in der Belüftungszone sich positiv auf das Bio-P auswirken.<br /><em>Reduktion der Fällmittel in die Biologie</em>: Die Konkurrenzsituation von Bio-P und Fällmitteln gilt es zu begrenzen. Hierzu kann eine Zwei-Punkt-Fällung mit einer Fällmitteldosierung in den Sandfang oder vorteilhafter in den Schlammwasserstapel erfolgen. Als unterstützende Massnahme wird eine Filtration des NKB Ablaufs empfohlen. Dies gewährt den Anlagenbetreibern einen Spielraum bei der Optimierung der Fällmitteldosierung im Fall dass durch die Reduktion der Fällmittel Probleme bei der Schlammabsetzbarkeit auftreten.<br /><em>Vermeidung der Phosphatrückbelastung</em>: Durch Belüftung oder Flotation des gestapelten Überschussschlammes lässt sich die rückgelöste Phosphatfraktion wieder in partikuläre Polyphosphate überführen und somit die Phosphatrückbelastung vermeiden.<br /> Für die Optimierung der biologischen Phosphorelimination ergibt sich kein alleiniger Lösungsansatz. Viel mehr wird sich diese aus einer Mehrzahl von integralen Massnahmen zusammenstellen müssen.

Only little is known about the micropollutants from urban areas discharged via combined sewer overflows during rain events. In urban catchments various sources of micropollution<br /> occur that change over time and with different kind of land uses. In Switzerland different rain regions and various land use types have to be considered to characterise the large variability of urban drainage systems. Thus a geographical information system based analysis of the urban areas in Switzerland combined with the modelling of the amount of pollutants released via combined sewer over flows during rain events is feasible to asses the dominant sources. Therefore a model was developed to determine the combined sewer over flow emissions loads of micropollutants for Switzerland. This model accounts for the main urban sources of micropollutants and the variation in the urban area of Switzerland.<br /> The overall model results show, that combined sewer over flow emissions of urban areas are an important contribution to the pollutant load in surface water. Especially for pollutants<br /> washed-off impervious areas, such as roofs or traffic surfaces, the load discharged via combined sewer over flow was estimated to be in the same range as the load discharged to the wastewater treatment plant. Thus the discharge via combined sewer over flow can result in acute effects on the environment. The result also emphasizes the importance of mitigation measures at the pollutant source rather then end-of-pipe measures.

L’objectif principal de cette étude est d’établir un état des lieux de la production et de la gestion des ordures fermentescible en Côte d’Ivoire en appliquant une méthodologie d’analyse de flux de matières. La commune de Marcory, à Abidjan, fut choisie comme zone d’étude. Le secteur des déchets solides y est caractérisé par l’absence d’une stratégie de gestion et de financement durable ainsi qu’un manque de cohésion au niveau du cadre institutionnel. Les résultats obtenus révèlent que la gestion sur le terrain repose sur un partenariat fragile entre les acteurs de la (pré)collecte et que l’enlèvement des ordures s’y fait de manière désorganisée. Bien que les principaux contributeurs aux flux de matières organiques soient les ménages, l’étude démontre que le processus clé du système se situe au niveau de la station de transfert des ordures. C’est pourquoi des mesures devraient être prises à ce stade afin d’augmenter la valorisation des ressources à disposition et ainsi améliorer l’environnement urbain des populations locales. Les résultats montrent également que la production d’électricité à partir de biogaz serait envisageable à Marcory à une échelle institutionnelle. Toutefois, celle-ci ne solutionnerait pas la totalité des problèmes liés à la gestion locale des déchets organiques.<br /><br /> The main objective of this study is to assess the current state of fermentable waste production and management in Côte d’Ivoire, by using a material flow analysis methodology. The district of Marcory, in Abidjan, was chosen as the study area. The solid waste sector is characterized in this district by the lack of a management strategy and of a sustainable funding system as well as by a deficiency of coherence at the institutional framework level. Obtained results show that the on-site management is based on a weak partnership among (pre)-collection actors and that waste collection is disorganized. Although households are the main contributors to the organic matter fluxes, this study shows that the key process of the system is at the waste transfer station level. For this reason, measures should be taken at this stage in order to increase the usage of available resources and, thereby, to enhance the urban environment of local populations. Additionally, results reveal that electricity production from biogas would be possible in Marcory at the institutional level. Nevertheless, this would not solve all the issues related to the local organic waste management.

One of the most important anthropogenic factors influencing freshwater systems globally is land use. Aquatic ecosystems are greatly influenced by the riparian zone (acting as a buffer between stream and watershed) but also the surrounding landscape. Several studies showed a direct linkage between surrounding land use and instream invertebrate and fish diversity. Land used for agriculture or urbanization can thus influence functional and structural processes in streams. To determine instream ecological conditions, leaf litter decomposition rates can be used. Only a small fraction of the organic carbon production of terrestrial plants is removed by herbivores or sequestered. This makes decomposition of plant litter one of the most important ecosystem processes in the biosphere. Changes in leaf litter decomposition rates can therefore reveal the impact of land use changes on streams.<br /> Decomposition of allochthonous leaf litter was assessed in the Gürbe river located south of Bern, Switzerland using the mesh bag method. This stream is influenced by agriculture and urbanization throughout its catchment area. Instream decomposition at these agricultural and urban influenced sites was determined by use of leaf packs in relation to relatively pristine sites in the same channel. Decomposition values observed indicate an acceleration in decomposition at anthropogenic influenced sites. Microbes probably contribute most to the decomposition process in this catchment. Coarse mesh bags (macroinvertebrate, physical and microbial decomposition) only showed 25% higher decomposition compared to microbial restricted fine mesh bag decomposition. Previous studies found similar results.<br /> Macroinvertebrate assemblages in the leaf packs differed as well along this gradient from pristine to land-use change influenced sites. Higher numbers of macroinvertebrates, as well as the more pollution tolerant macroinvertebrate species, were found at the influenced sites. Pristine sites showed the lowest number of macroinvertebrates but had higher diversity indices, indicating less single species domination at these sites. Chironomidae (Diptera) were dominant in the leaf packs, taking advantage of the trapped particles as well as the biofilm on the leaves. Plecoptera numbers were locally also very high. This particularly holds for the pristine sites.<br /> Decomposition in coarse mesh bags was higher compared to fine mesh bag decomposition throughout the catchment. However, shredder densities were low at all sites. This could indicate the importance of physical factors contributing to decomposition, next to dominance of microbes in the decomposition process in this stream. Fungal biomass on leaves did not show a pattern related to land use changes, and results were very variable within and among sites. Previous studies indicate that increased nitrate concentrations stimulate microbial growth and increase in fungal diversity on leaves, resulting in higher decomposition rates. Possibly due to the presence of Chironomidae (which feed on microbial biofilm on leaves) in the leaf packs, higher fungal biomass was not found on leaves in agricultural/urban influenced sites. These results suggest that decomposition is higher at agricultural and urban influenced sites because of higher numbers of macroinvertebrates and not due to microbial decomposition.

Environmental stress is a common source of natural selection, and geographic variation in environmental stress may lead to adaptive divergence among populations. However, natural populations are often exposed to multiple stressors at the same time, and the mechanisms of adapt at ion to complex environments is still largely unknown and may not be predictable from studies of single stressors. As acidificat ion of surface waters is an important environmental issue, particularly in Scandinavia, and because the globally distributed pathogen Sapro/egnia (water mold) can contribute, especially in combination with other stressors, to declines of amphibian populations, I studied the interactive effects of acidity (pH) and Saprolegnia infections on embryonic performance (survival, hat ching time and hat chling size) of the moor frog, Rana arva/is. Further I tested if the jelly that surrounds the embryos may modify among population responses to these two stressors. [...]

In aquatic systems such as rivers or ponds, input concentrations of most pollutants have been observed to fluctuate and also tend to occur in sequential input pulses. For a good risk assessment and for defining water quality criteria, effects of such exposure patterns need to be estimated appropriately. Previous studies have detected carry over toxicity in organisms exposed to sequential exposure of chemicals acting with the same mode of action, namely inhibition of acetylcholine esterase (AChE). The aim of this master thesis was first of all to test whether such carry over toxicity also occurs in sequential exposure of chemicals with different modes of action (MoA). Secondly, if such carry over does take place, then the performance of the threshold damage model in predicting the survivals of the given experiment would be tested. Additionally, the toxicodynamic parameters of DNOC were estimated in order to run the prediction. [...]

When isogenic populations of bacteria are killed by antibiotics, the decrease of living cells usually follows an exponential curve. This implies that while most of the cells die in the very beginning, some can survive for long times. Those differences in survival time are due to a distribution of non-­‐genetic resistances between the individual cells. It could be shown that the rate of killing is proportional to the growth rate of bacterial cultures that were grown under different conditions. However, it was unknown if differences in growth rates between single cells can affect the survival time. Here we show that differences in interdivision times between single Caulobacter crescentus cells before the administration of ampicillin influence the survival time under antibiotic stress. Cells that grow slower survive antibiotic stress longer. This could have implications on the development of new antibiotics, particularly for diseases where single surviving cells are a major problem.

In this exploratoryqualitativecomparativecase study I apply the theoretical framework of institutional entrepreneurship to develop a perspective on companies’ strategies to create or change institutional structures in the emerging field of smart grids. I find that smart grids are envisioned to be a complex assemblage of heterogeneous technologies and that the emergence of this field signifies a current transformation process in the electricity supply sector. The study shows that actors are engaging in various strategic institutional entrepreneurship activities in order to influence the development of a common vision, demonstration projects, technological standards, regulatory framework of electricity markets, business models, associations/networks and conferences in order to try to create technological innovations in a utility sector. As institutional entrepreneurs engage in collective action to try to mobilize resources and foster embedded and distributed agency, they attempt to strategically steer the trajectory of the enabled agency of other actors through defining the settings in which agency can emerge. Engaging in influencing the creation of new market concepts and changing the dynamics of the electricity markets can create a need for internal organizational change, as actors’ own market roles can get redefined in the process. Small organizations can implement internal change faster than large organisations, and therefore also have strategic advantages compared to large, powerful organisations when it comes to engaging in strategic institutional entrepreneurship. In this context, individual institutional entrepreneurs have to be highly skilled knowledge managers who are working simultaneously towards fostering divergent institutional change outside and inside their organisations by strategically creating and directing knowledge flows.

<em>Problem</em>: The most wastewater produced in modern countries is treated by centralised wastewater treatment plants which have a low technological flexibility and high financial costs. The phosphate in the wastewater, a nutrient, is burned and diverted into the rivers. Since the reserves of phosphate rock are limited this thesis tries to define a way to recover it by electro-coagulation.<br /><em>Solution</em>: Novaquatis (EAWAG) propose to separate the urine from wastewater and to treat it separately in a small scale reactor to recover the phosphate.<br /> A method for the phosphate recovery from urine is the struvite precipitation. Struvite is usually obtained by the addition of magnesium mineral. The dosage control and storage of the powder aren’t well adapted to small reactors. The electro-coagulation of phosphate has potential to be a better solution at the household scale.<br /><em>Process</em>: The electro-coagulation of phosphate from urine is based on the electro-dissolution of a magnesium electrode. The dissolved magnesium reacts with phosphate and ammonium, present in urine, to struvite. The struvite is recovered and sold as fertilizer.<br /><em>Thesis</em>: The electro-coagulation isn’t yet a well known process. The thesis tried to define and to optimize the whole process. The design of a small scale reactor, a simple controlling and monitoring possibilities are studied. Finally the economical and technical suitability of the process is evaluated.<br /><em>Method</em>: Two metal plates, used as electrodes, are put into a one litre reactor filled with a synthetic solution simulating urine. The working electrode is made of magnesium and the counter-electrode of stainless steel. A constant voltage was applied, inducing the dissolution of magnesium. Many variables were measured during the phosphate elimination, like pH, current, conductivity, etc. A series of experiments was set up to optimize the process.<br /><em>Experiment</em>: To understand the process some basic experiments were done. Afterwards the electro-coagulation was performed with different voltages to find out an optimal one. It appeared that in some conditions the magnesium plate was covered with a white layer, a struvite layer, which inhibits the electro-coagulation process. How to prevent the formation of this layer is described.<br /><em>Results</em>: The first results were promising, the struvite was actually produced and the phosphate almost completely removed. The optimal voltage was defined in the range of +1.0V to +1.25V avoiding the struvite layer formation on the working electrode by lower voltage and the electrolysis of the solution at higher voltage.<br /> A nice way to monitor the process is to follow the changes of the conductivity of the solution and the change of the working electrode potential. The rate of electro-dissolution of magnesium is dependent on the current, so by setting the current, we can control the process well, even stop it.<br /><em>Suitability</em>: The different experiments showed the process of electro-coagulation is undoubtedly a technologically suitable way to recover phosphate from urine. The process can only be profitable considering the saving costs by the wastewater treatment plant. The cost of the production of the magnesium electrode is difficult to be compensated by the selling of the struvite fertilizer.<br /><em>Conclusion</em>: The result of this thesis will certainly promote the process of electro-coagulation, since the process is working well and easy to control. The different open points are mentioned in order to confirm the promising results described in this project.

The concentrations of pesticides and other micropollutants were measured during high discharge events in the lower catchment of the river Thur which is located in the Cantons of Zurich and Thurgau in northeastern Switzerland. Sampling campaigns were carried out from April to June of 2010. The main objective was to trace peak concentrations in the field site by sampling the river and the groundwater from a non-restored transect and a restored transect of the Thur. The behavior of the pollutants through the aquifer was compared for the restored and non-restored transects. The compounds found in higher concentrations included the pesticides MCPA and Diuron as well as micropollutants from urban settlements such as Benzotriazole, Carbamazepine and 4-Acetamidoantipyrine.<br /> The concentrations of pesticides detected in the first wells of both transects were low compared to the concentrations in the Thur. MCPA concentrations were the highest pesticide concentrations detected in both the river and in the groundwater (650 ng/L in the Thur and 49 ng/L in the restored transect) despite the fact that its agricultural use is not so important in the catchment. Degradation could be observed for MCPA and Diuron through the groundwater wells. MCPA appeared to be the compound with higher importance in the river during the time studied. Pesticide concentrations in the groundwater did not seem to represent a risk compared to other types of micropollutants such as Benzotriazole and Carbamazepine which were found in higher concentrations in both transects.<br /> Carbamazepine was identified as a persistent pharmaceutical in both well transects while in contrast the concentrations of 4-Acetamidoantipyrine decreased importantly through the groundwater transects. Relatively high concentrations of certain corrosion inhibitors and pharmaceuticals (such as the metabolite 4-Acetamidoantipyrine) can reach further into the forest transect than into the pumping station transect due to the difference in travel times between both transects. Based on travel times it seems that the river restoration allows compounds to infiltrate further into the aquifer without generating a decrease in the concentrations. This is a disadvantage for compounds which are present in high concentrations in the river and which need long contact times in the aquifer in order to be degraded.

Nach dem Brand einer Lagerhalle im Industriegebiet Schweizerhalle bei Basel gelang ein Teil der gelagerten Chemikalien durch das Löschwasser in den Rhein. Aufgrund der grossen Schaden an der Fauna des Rheins gewann die Uberwachung von Gewässern auf Schadstoffe in den letzten beiden Jahrzehnten zunehmend an Bedeutung. Zu diesem Zweck wurde die Rheinuberwachnugsstation Weil am Rhein errichtet, die mit einem umfangreichen Messprogramm uber die Qualität des Rheins wacht. Im Bereich der organischen Spurenanalytik wurde dort bisher weitgehend auf gaschromatographische Methoden zuruckgegriffen, wodurch vor allem unpolare und flüchtige Substanzen erfasst wurden. Um die Analytik polarer organischer Mikroverunreinigungen zu verstärken, wurde kurzlich ein flüssigchromatographisch betriebenes LTQ-Orbitrap Massenspektrometer angeschafft, mit welchem neben der konventionellen Analytik auch die Suche nach unbekannten Kontaminationen vorangetrieben werden soll. Dieses sogenannte Non-Target Screening ist jedoch zum momentanen Zeitpunkt noch nicht so weit entwickelt, dass es sich in den bestehenden Routinebetrieb einfugen liesse. In dieser Masterarbeit werden Ansatze aufgezeigt, wie die enorme Datenmenge des Massenspektrometers qualitativ aufbereitet und quantitativ reduziert werden kann. [...]

Public awareness of the issue of micropollutants in aquatic systems is increasing. It was shown that micropollutants occur also in drinking water resources in relevant concentrations. As Lake Constance serves as a large drinking water reservoir, it is important to investigate the occurrence and fate of micropollutants from their sources into rivers and finally into the lake. In a previous study, which comprehensively investigated micropollutants in the open water of Lake Constance, it was found that most substances in the lake were originated from urban areas. The seven most frequently detected micropollutants were carbamazepine, diclofenac and sulfamethoxazole (pharmaceuticals), benzotriazole and methylbenzotriazole (anti‐corrosives) as well as sucralose and acesulfame (artificial sweeteners). These substances were therefore selected to be investigated in further detail. The main goals of this study were firstly to determine current contamination hotspots of the seven selected micropollutants in the catchment of Lake Constance and to investigate how the current load input into Lake Constance affects its water quality. Secondly, different strategies to reduce these hotspots in the catchment and in the lake were evaluated. The reduction of micropollutants was considered to be achieved by an upgrade of waste water treatment plants (WWTPs) by an advanced treatment step such as ozonation.

Ziel dieser Arbeit war es, mit dem „Handbuch für die Erfolgskontrolle von Fliessgewässerrevitalisierungen“ des Rhone-Thur Projekts (Woolsey et al. 2005) ökologische Erfolgskontrollen an zehn kleineren Bächen durchzuführen, wobei der Fisch als biotischer Indikator eingesetzt wurde. Hierzu wurde aus dem Handbuch ein Set von 9 Indikatoren zusammengestellt, mit welchen die ökologischen Ziele bewertet werden können. Die Erfolgskontrollen wurden in einer räumlichen Untersuchung (Post-Treatment) durch Vergleich ınit kanalisierten Strecken durchgeführt. In allen Teststrecken wurden neben einmaligen quantitativen Abfischungen die ausgewählten Indikatoren erhoben. [...]<br />

Engineered silver nanoparticles (AgNP) are already present in a wide variety of consumer products and therefore are susceptible to be released in significant amounts into the aquatic environment. Our understanding about their interactions with aquatic organisms and their potential hazards is still poor. Here, the toxicity to photosynthesis and the uptake of AgNP and free silver ions (Ag⁺) were investigated in a cell wall free mutant of the green alga <em>Chlamydomonas reinhardtii</em> (CC-400) and compared with existing data for the wild type (CC-125) (Navarro et al. 2008b).<br /> In short-term toxicity tests (i.e. 1 and 2 hours), the mutant algae were exposed to different AgNP and AgNO₃ concentrations in 10 mM MOPS buffer pH 7.5. Then, the photosynthetic yield was measured using PAM-fluorometry. Under the same experimental conditions, intracellular silver accumulation was determined at different time points between 5 and 60 minutes by ICP-MS.<br /> After 1 h of exposure, the particles (EC₅₀ = 1666 nM) showed a lower toxicity compared to AgNO₃ (EC₅₀ = 35.8 nM). The EC₅₀ value for AgNP after 2 h of exposure was decreased by 70%. As expected (Navarro et al. 2008b), an excess of cysteine was able to abolish the toxicity of both treatments, suggesting an Ag⁺-mediated toxicity. Uptake experiments indicate a higher intracellular silver concentration in CC-400. Upon comparison to CC-125, the higher sensitivity of CC-400 points to a protective role of the cell wall.

In the bid to improve fish stocks in natural environments, man has directly impacted upon natural waters through different interventions. Hatchery programs have been used to restore, supplement and conserve fish populations in the wild. However, whether this intervention actually helps in improving wild fish stocks remains largely unanswered. Recent studies have shown that hatchery fish have lower fitness, compared to wild fish, when they are released into natural environments. Many of the results from these studies, however, suffer from the lack of statistical power to detect the fitness difference between groups.<br /> In this study, the ability of four statistical tests in detecting fitness difference between two groups (hatchery fish versus wild fish) was investigated under many different circumstances and conditions. Particularly, statistical power of the permutation test, One-Way ANOVA, Student <em>t</em>-test and the Wilcoxon Rank-Sum test and their false positive rates were evaluated using computer simulations mimicking reproductive fitness of wild fish and hatchery fish. Two distributions, Poisson and Negative binomial, were assumed as a fitness distribution in this study.<br /> In all tests, the power to identify the fitness difference strongly depended on the degree of intrinsic fitness difference between two groups, the number of parents sampled, and the number of offspring sampled. The fitness distribution also had a large influence in the power of the tests. Among the tests, the permutation test showed the highest power in a wide range of parameter values, suggesting that this is the best available test for detecting the<br /> fitness difference between groups at this moment. The false positive rates were not different<br /> among these tests, and generally consistent with a theoretical prediction (i.e., around 5% at<br /> the 5% level of statistical significance).<br /> These results suggest that the permutation test should be used in detecting the reproductive fitness between groups. However, when sample sizes are limited both in parents and offspring, the power of the permutation test is also limited. Thus, a better test needs to be developed to detect a small-to-intermediate level of difference in reproductive fitness. In addition, the numbers of parents and their offspring to be sampled should be carefully considered when designing the experiments, because both numbers have a considerable importance on the power of the statistical tests and hence on detectable fitness differences.

All of the sulfur in human excreta ends up as dissolved sulfate in the urine. If released to the environment, sulfate is not problematic because it is stable. However, if it comes in contact with water containing a large amount of organics, sulfate transformation to sulfide starts as soon as the water is depleted of oxygen and nitrate, producing a bad smell and intoxicating the microbiology. The largest problem in wastewater treatment is probably the corrosion in anaerobic sewer systems due to sulfide oxidation. Another problem is the H2S production during biogas generation, which necessitates gas washing. Since it is an essential plant nutrient [18] and a widely applied element in industry [23], recovering sulfur from urine can be of interest. Within the scope of a master thesis of 16 weeks the bioelectrochemical sulfate removal from stored, source-separated urine was analyzed. The iodometric method was applied to urine in order to measure dissolved sulfide, thiosulfate, and sulfite. In a microbial electrolysis cell a sulfate load of 4.10 ± 0.17 <em>g</em> SO²⁻₄ -<em>S m</em>⁻² biofilm surface <em>d</em>⁻¹ was microbially transformed to sulfide which was subsequently oxidized to elemental sulfur at an anode potential of 0.06 V. Comparison between dissimilatory sulfate reduction with and without electrochemical sulfide oxidation showed an increase of the sulfate degradation rate of 30 % to 1.48 <em>g</em> SO²⁻₄ -<em>S m</em>⁻² biofilm surface <em>d</em>⁻¹ when sulfide was electrochemically oxidized. A mass balance of sulfur over the reactor showed that dissolved sulfur disappeared in the reactor. Based on the sulfur balance, a sulfide oxidation rate was estimated yielding 0.35 <em>g</em> <em>SH</em>⁻-<em>S</em> <em>m</em>⁻²<em>d</em>⁻¹. The process combination of biological sulfate reduction and subsequent partial sulfide oxidation to elemental sulfur was applied successfully to stored, source-separated urine. In a future work, the process parameters need to be improved, first of all the tradeoff between biofilm surface on the anode and free anode surface for sulfide oxidation. A separation of the biological and electrochemical processes would be suitable for further experiments on the bioelectrochemical sulfate reduction. Additionally a more throughout analysis of the conversion of the sulfur species in the reactor should be done. The limitations of the sulfate degradation need to be analyzed.

The increase of greenhouse gases (GHG) in the atmosphere, resulting from both natural sources as well as from human activities, has become a heated global issue. Reducing their concentration is a subject being tackled my many scientists and companies. Although water vapour and carbon dioxide are very abundant GHGs, methane has a 21 times stronger global warming potential (EPA, 2006) and needs to be reduced likewise.<br /> Due to the increase in population and rapid industrialization, another challenge facing the world today is solid waste management, and in particular its disposal. In developing countries, the increasing amount of waste is typically crudely dumped. As the municipal solid waste consists to a big extent of organic material, methane is produced under anaerobic conditions on dumpsites. As a means of dealing with kitchen waste, some biogas plants have been installed in several households and institutions in East Africa, especially in Dar es Salaam.<br /> This study identifies the potential for institutional biogas plants to reduce greenhouse gas emissions and shows their possibilities and limitations to become a carbon project. The study was divided into two major sections, which included data collection through semi-structured interviews conducted in Dar es Salaam, and calculations made using the 2006 IPCC guidelines methodologies. The baseline GHG emissions for the current waste management system were calculated both for the emissions resulting from anaerobic digestion on the dumpsite, as well as from transportation of waste. The project emissions from the biogas plant were considered to be the physical leakages as well as emissions through the effluent.<br /> The study showed that the GHG emissions resulting from transportation and decomposition of all organic waste dumped in Dar es Salaam is 300,153 tCO2e/year, of which kitchen waste is responsible for 52%. Due to the fast degradation rate of kitchen waste, there is need to deal with this fraction almost immediately.<br /> The case of the Azania secondary school, which is equipped with ARTI biogas plants to treat their food leftovers, showed that 56% of the GHG emissions could be reduced by treating all kitchen waste in biogas plants. This figure would even increase to 76% if the ARTI design was improved and gas loss from the biogas plants was minimized.<br /> In order to comply with the requirements for a small-scale CDM project, a maximum of 7500 institutions similar to Azania secondary school could install biogas plants so that 60,000 CER per year are not exceeded. To cover the transaction costs of a voluntary carbon offsetting project and make it economically attractive, a minimum of 1585 institutions would be needed.<br /> Such a project would also comply with CDM regulations since it would contribute to sustainable development of the country by improving the waste management and providing renewable cooking energy for the people.

Phosphorus is an essential compound for plants. But the major phosphorus source for fertilizers - phosphate rock - is a limited resource. To close the nutrient cycle, phosphorus should be recovered from waste streams. Urine has a high phosphate content, which can be recovered as struvite.<br /> Struvite is a magnesium-ammonium-phosphate (NH₄MgPO₄ · 6 H₂O) and can be used as a slow release fertilizer in agriculture. As magnesium is the limited compound in urine, a magnesium source has to be added for struvite precipitation. Conventional methods consist in the dosage of a magnesium salt. Electrocoagulation on the other hand dissolves magnesium electrochemically from a magnesium electrode.<br /> For electrocoagulation magnesium is oxidized to magnesium ions at the magnesium anode, water is reduced to hydrogen gas at the steel cathode. To enhance the reaction speed a voltage source can be added. The voltage source can either be applied between the magnesium and a reference electrode (magnesium potential, three electrode configuration) or between the magnesium and the steel electrode (cell voltage, two electrode configuration). The advantage of the three electrode configuration being that the magnesium potential determines directly the reactions that can take place at the magnesium electrode.<br /> Two sets of experiments have been conducted: voltammetry and batch experiments. For voltammetry the applied magnesium potential was changed with time to detect electrode characteristics. For the batch experiments the voltage source (magnesium potential or cell voltage) was kept constant over time.<br /> Voltammetry and batch experiments showed that the magnesium electrode is sensitive to layer formation at magnesium potentials below -800 mV. An electrode potential of -600 mV seemed to be a very appropriate potential concerning reaction speed and energy consumption. An electrocoagulation reactor can either be operated by applying an electrode potential or a cell voltage. Applying a cell voltage will be the easier configuration, as no potentiostat is needed. A cell voltage of at least 1000 mV should be applied to prevent layer formation.<br /> The monitored cell voltage/electrode potential (depending on electrode configuration) showed a maximum/minimum as phosphate was removed from urine. It can therefore be used as a parameter to control the magnesium dissolution in order to not waste magnesium. A continuous reactor could then be operated in sequencing batch mode, using three tanks:<br /> storage tank, electrocoagulation reactor and settling tank.<br /> It has been shown that electrocoagulation is a very functional method to recover struvite from natural urine. The advantage of electrocoagulation against chemical dosing will be found in a high magnesium efficiency and in a high automation possibility.

The history of intensive river damming during the last 100 years promoted hydroelectricity, irrigation and flood control, but also resulted in serious environmental problems. By altering the flow regime of rivers, dams influence the transport of particles, carbon (C), and nutrients from land to ocean. This impact on biogeochemical cycles is aggravated by reservoir-internal processes, such as primary production, mineralization, and greenhouse gas emissions. Consequently, dam operations often lead to deterioration of downstream ecosystems. Despite these problems, hydropower represents a valid option for economic development in Sub-Saharan river basins, where only 5% of the large potential for hydropower is being exploited. [...]<br /><br />Durch den in den letzten 100 Jahren weltweit intensiven Bau von Staudammen wurden Wasserkraft, Bewasserung und Hochwasserschutz gefordert, gleichzeitig führte dies aber auch zu ernsthaften ökologischen Problemen. Staudämme und die zugehörigen Stauseen beeinflussen das Abföussregime von Flussen und damit auch den Transport von Partikeln, Kohlenstoff (C) und Nährstoffen von den Kontinenten in die Ozeane. Diese Beeinflussung<br />der biogeochemischen Kreisläufe beruht nebst der Sedimentrüuckhaltung auch auf den stausee-internen Prozessen, namentlich der Primarproduktion, der Biomineralisation und der Emission von Treibhausgasen. Als Folge dieser Beeinflussungen beobachtet man eine negative Beeintrachtigung der flussabwarts gelegenen Ökosysteme. Trotz dieser Probleme stellt die Wasserkraft eine wertvolle Möglichkeit zur nachhaltigen wirtschaftlichen Entwicklung in den Flusseinzugsgebieten südlich der Sahara dar, wo nur ~5% des grossen Potentials der Wasserkraft genutzt wird. [...]

This work focuses on the determination of noble gas temperatures (NGTs) in water inclusions in stalagmites with the aim to infer the cave temperature prevailing at the time the inclusions were formed. The method is based on the temperature-dependent solubilities of noble gases (He, Ne, Ar, Kr and Xe) in water, which allows calculating the water temperature from measured noble gas concentrations if the salinity and the atmospheric pressure during gas exchange are known. In recent years, stalagmites are increasingly being used as climate archives, as they provide highly resolved and well-dated records of past climate conditions over glacial-interglacial time intervals. Stalagmites contain 0.01-0.1 wt.% of water, which is incorporated into the calcite crystals in the form of water inclusions during stalagmite growth. Noble gas analysis in water inclusions in stalagmites hence offers the potential to directly and quantitatively determine cave temperatures, which is an important prerequisite for the interpretation of δ¹⁸O and δ¹³C records in the stalagmite calcite. [...]<br /><br />Die Löslichkeit von atmosphärischen Edelgasen (He, Ne, Ar, Kr und Xe) in Wasser ist neben dem atmosphärischen Druck und der Salinität des Wassers auch von der Temperatur des Wassers abhängig. Deshalb kann aus den Edelgaskonzentrationen, die in einer Wasserprobe gemessen werden, die Temperatur des Wassers zum Zeitpunkt des letzten Gasaustausches berechnet werden. Das Ziel dieser Arbeit ist es, diese Methode in Wassereinschlüssen in Stalagmiten anzuwenden, um die so genannte „Edelgastemperatur“ des Wassers zu bestimmen, die zum Zeitpunkt des Einschlusses in die wachsenden Kalzitkristalle vorherrschte.<br />Stalagmiten wurden in den letzten Jahren immer häufiger als Klimaarchive verwendet, da sie über lange Zeiträume wachsen (bis zu mehrere 105 Jahre) und gut datierbare, hoch aufgelöste Klimainformationen enthalten, vor allem in der isotopischen Zusammensetzung des Kalzits (δ¹⁸O, δ¹³C). Stalagmiten beinhalten ca. 0.01-0.1 gew.% an Wasser in Wassereinschlüssen, die während des Wachstums des Stalagmiten in die Kalzitkristalle eingeschlossen wurden. Die temperaturabhängige Löslichkeit von Edelgasen in Wasser erlaubt es im Prinzip, die Höhlentemperatur über Edelgasanalysen in den Wassereinschlüssen direkt und quantitativ zu bestimmen. Dies wäre für die Interpretation der δ¹⁸O- und δ¹³C Zeitreihen in Stalagmiten wichtig, da die isotopische Zusammensetzung des Kalzits unter anderem auch von der Höhlentemperatur abhängt. [...]

The availability of drinking water is a key health issue in developing countries. Over 1.2 billion people lack access to safe drinking water today. They are using contaminated surface water from rivers, ponds and unprotected wells. This causes a high frequency of diarrhoeal diseases, which are life-threatening, especially for children under the age of five. About 4000 young children die from diarrhoea every day. The World Health Organization (WHO) has recognized the problem and promotes low-cost and effective home-based water treatment methods. Solar disinfection (SODIS) is one of these methods. In many parts of the world the UVA part of sunlight can be employed for disinfection purposes: 6 hours of exposure of unsafe drinking water to the sun in plastic PET bottles results in an inactivation of enteric pathogens (bacteria, protozoa and viruses) of several orders of magnitude. Over 3 million people in 33 countries are currently using SODIS in daily life. Although the method is widely used in practice, the cellular mechanisms leading to bacterial death during solar UVA irradiation still leaves many open questions. This thesis addresses some of these questions. [...]<br /><br />Die Gesundheit der Bevölkerung in Entwicklungsländern hängt stark von der ausreichenden Versorgung mit Trinkwasser ab. Über 1.2 Milliarden Menschen haben heute keinen Zugang zu sicherem Trinkwasser. Sie benützen meistens Oberflächenwasser von fragwürdiger Qualität aus Flüssen, Teichen und ungeschützten Brunnen. Dies verursacht eine häufiges Auftreten von Durchfallerkrankungen, die vor allem für Kinder unter fünf Jahren lebensgefährlich sein können. Täglich sterben etwa 4000 Kinder in diesem Alter an Durchfall. Um diesen Problemen zu begegnen, fördert die Weltgesundheitsorganisation WHO günstige und effiziente Wasserbehandlungsmethoden für einzelne Haushalte. Dazu gehört auch die Solare Desinfektion (SODIS). Der UV-Anteil des Sonnenlichts wird dabei für Desinfektionszwecke ausgenützt. Krankheitserreger (Bakterien, Protozoen und Viren) im fragwürdigen Trinkwasser werden innerhalb von 6 Stunden in PETPlastikflaschen an der Sonne um mehrere Zehnerpotenzen reduziert. SODIS wird heute von 3 Millionen Menschen in 33 Ländern täglich genutzt. Obwohl die Methode in der Praxis so grossen Anklang findet, weiss man noch wenig über die zellulären Inaktivierungsmechanismen während der UVA-Desinfektion. Diese Dissertation beantwortet einige Fragen, die in diesem Zusammenhang gestellt werden können. [...]

In recent years, solid waste management awareness in low and middle‐income countries has gradually increased, resulting in improved collection coverage and reduced dumpsites and landfills. Especially valorisation of recyclables enjoys a growing popularity, be it through a motley crew of scavengers or via official recycling services run by local government authorities. However, since the organic fraction of municipal organic waste is still considered less valuable than other waste products, such as paper, glass or metal, it is often excluded from this valueadded chain. Despite its energy content, it ends up on streets or accumulates on dumpsites, where it attracts vector diseases and produces greenhouse gases. The organic waste treatment technology, using larvae of the black soldier fly, <em>Hermetia illucens</em>, paves the way to a financially sustainable treatment option, assigning organic refuse its inherent value to compete against other recyclables. The feeding activity reduces up to 80% of the biomass of organic waste products, such as market/kitchen waste, animal manure or even human faeces. The last larval stage, the so‐called prepupa, consists of ~40% protein and ~30% fat, making it a valuable alternative to fishmeal in animal feed. [...]<br /><br />Die Situation im Bereich des Abfallmanagements in Schwellen‐ und Entwicklungsländern hat sich in den letzten Jahren massgeblich verbessert. Vor allem wiederverkäufliche Materialien landen heute anstatt auf improvisierten Müllkippen oder im Strassengraben öfters in Recyclingzentren, sei es durch lose organisierte Truppen von Müllsammlern, oder durch offizielle Sammeldienstleistungen der Gemeinden. Allerdings wird dem organischen Anteil im Haushaltsabfall oft jeglicher Wert abgesprochen und es werden ausschliesslich „wertvolle“ Materialien wie Papier, Glas oder Metall eingesammelt. Trotz seines Energiegehalts bleibt organischer Müll in Strassen, Wasserläufen oder Abfallhalden liegen, wo er Krankheitsvektoren anzieht und durch unkontrollierte anaerobe Prozesse Klimagase produziert. Die Methode, organische Wertstoffe mittels Larven der Waffenfliege, <em>Hermetia illucens</em>, in ein protein‐ und fettreiches Produkt umzuwandeln, gibt diesem bisher vernachlässigten Anteil des Haushaltabfalls einen Wert und ermöglicht auch für organische Abfälle eine ökonomisch nachhaltige Abfallwirtschaft. Die Fressaktivität der Larven reduziert Abfallstoffe wie Markt‐ und Küchenabfälle, Tiermist oder sogar menschliche Fäkalien um bis zu 80%. Das letzte Larvenstadium, die sogenannte Prä‐Puppe, besteht aus ca. 40% Protein und ca. 30% Fett und stellt dadurch eine wertvolle Alternative zum heute in Tierfutter verwendeten Fischmehl dar.

Local populations often inhabit contrasting habitats, which is predicted to cause divergent natural selection and drive adaptive divergence. Contemporary populations are increasingly exposed to environmental stressors, which is an important selective factor creating local adaptation. An increasing number of studies on natural populations have suggested a major role for divergent selection in driving phenotypic differentiation between populations. However, the selective agents causing phenotypic divergence are often not known. Furthermore, organisms are likely experiencing multiple selective agents in nature, which can result in trade-offs, and affect the extent of phenotypic divergence. However, it is still largely an open question how organisms adapt to complex environments. As different sources of phenotypic variation (such as direct genetic vs. maternal effects) can have fundamental consequences for the maintenance of genetic variation and local adaptation we need a better understanding of relative importance of these sources. Comparing populations along an environmental stress gradient can be a powerful way to test how environmental stress drives adaptive divergence between populations, if different selective factors affect the extent of phenotypic divergence, and what is the quantitative genetic basis of population divergence. [...]<br /><br />Lokale Populationen bewohnen häufig unterschiedliche Habitate, was zu divergenter natürlicher Selektion und adaptiver Divergenz führen kann. Heutige Populationen sind immer häufiger anthropogenem Umweltstress ausgesetzt, was ein wichtiger Selektionsfaktor ist, der lokale Anpassung kreieren kann. Immer mehr Studien, dass divergente Selektion eine Hauptrolle in der phänotypischen Differenzierung zwischen natürlichen Populationen spielt. Die selektiven Faktoren sind jedoch häufig nicht bekannt. Organismen in der Natur sind zudem stets mehreren selektiven Faktoren ausgesetzt, was zu Kompromissen führen und daher das Ausmass der phänotypischen Divergenz beeinflussen kann. Da unterschiedliche Quellen von phänotypischer Variation (wie direkte genetische oder maternale Effekte) wichtige Konsequenzen für die Erhaltung der genetischen Diversität und lokaler Anpassung haben, brauchen wir ein besseres Verständnis über die relative Wichtigkeit dieser Quellen. Anhand eines Vergleichs von Populationen entlang eines Stressgradienten kann man testen, ob Umweltstress zu adaptiver Divergenz zwischen Populationen führen kann, ob unterschiedliche Selektionsfaktoren das Ausmass der phänotypischen Divergenz beeinflussen und was die quantitative genetische Basis der Divergenz ist. [...]

Dissolved oxygen strongly influences water quality and the transport of this critically important constituent is controlled by turbulence. The transport of dissolved oxygen in freshwater systems, from the surface through the stratified water column, the bottom boundary layer, and finally into the sediment is the key subject of this thesis.<br />To evaluate the effects of bottom boundary turbulence on sediment oxygen uptake rate, diffusive boundary layer thickness, and sediment oxic zone depth, highresolution microprofiles across the sediment-water interface and current data within the bottom boundary layer of Lake Alpnach were measured. During a full cycle of seiching, the dissolved oxygen flux was evaluated from both sides of the sedimentwater interface. The results showed that in response to decreased turbulence resulting from lower currents, the diffusive boundary layer thickness increased and the oxygen penetration depth as well as the dissolved oxygen flux into the sediment decreased over a time span of hours. These results reveal the transient nature of sediment oxygen uptake and the importance of accurately characterizing turbulence when estimating oxygen fluxes at the sediment. [...]<br /><br />Die Wasserqualität von Seen und Flüssen wird massgeblich durch gelösten Sauerstoff beeinflusst. Der Transport von gelöstem Sauerstoff in Gewässern ist abhängig von der Turbulenz. Das Kernthema dieser Dissertation ist den Transportweg des gelösten Sauerstoffs von der Seeoberfläche durch die Wassersäule und die Bodengrenzschicht bis ins Sediment besser zu verstehen.<br />Im Alpnachersee wurden hoch aufgelöste Sauerstoff-Mikroprofile durch die Sediment-Wasser Grenzschicht und Strömungsgeschwindigkeiten in der angrenzenden Bodengrenzschicht gemessen. Damit konnten die Auswirkungen der Turbulenz in der Bodengrenzschicht auf den Sauerstoffverbrauch des Sediments, auf die diffusive Grenzschicht und die Sauerstoffeindringtiefe analysiert werden. Während eines vollständigen Seichezyklus (periodische interne Wellenbewegung) wurde der Sauerstofffluss über und im Sediment quantifiziert. Die Ergebnisse zeigen, dass aufgrund reduzierter Turbulenz resultierend aus der geringen Strömung bei der Strömungsumkehr der Seiche, die diffusive Grenzschichtdicke zunimmt und die Sauerstoffeindringtiefe sowie auch der Sauerstofffluss ins Sediment abnehmen und dies in einer Periode von wenigen Stunden. Diese Ergebnisse zeigen die periodischen Schwankungen des Sauerstoffverbrauchs im Sediment und die Bedeutung einer genauen Charakterisierung der Turbulenz, um die Sauerstoffflüsse in das Sediment quantifizieren zu können. [...]