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Institut
- Fakultät Nachhaltigkeit (128) (entfernen)
Existing institutions no longer appear to be sufficiently capable to deal with the complexity and uncertainty associated with the wicked problem of sustainability. Achieving the required sustainability transformation will thus require purposeful reform of existing institutional frameworks. However, existing research on the governance of sustainability of sustainability transformations has strongly focused on innovation and the more "creative" aspects of these processes, blinding our view to the fact that they go hand with the failure, decline or dismantling of institutions that are no longer considered functional or desirable. This doctoral dissertation thus seeks to better understand how institutional failure and decline can contribute productively to sustainability transformations and how such dynamics in institutional arrangements can serve to restructure existing institutional systems. A systematic review of the conceptual literature served to provide a concise synthesis of the research on "failure" and "decline" in the institutional literature, providing important first insights into their potentially productive functions. This was followed up by an archetype analysis of the productive functions of failure and decline, drawing on a wide range of literatures. This research identified five archetypical pathways: (1) crises triggering institutional adaptations toward sustainability, (2) systematic learning from failure and breakdown, (3) the purposeful destabilisation of unsustainable institutions, (4) making a virtue of inevitable decline, and (5) active and reflective decision making in the face of decline instead of leaving it to chance. Empirical case studies looking at the German energy transition and efforts to phase out coal in the Powering Past Coal Alliance served to provide more insights on (a) how to effectively harness "windows of opportunity" for change, and (b) the governance mechanisms used by governments to actively remove institutions. Results indicate that the lock-in of existing technologies, regulations and practices can throw up important obstacles for sustainability transformations. The intentional or unintentional destabilisation of the status quo may thus be required to enable healthy renewal within a system. This process required active and reflective management to avoid the irreversible loss of desirable institutional elements. Instruments such as "sunset clauses" and "experimental legislation" may serve as important tools to learn through "trial and error", whilst limiting the possible damage done by failure. Focusing on the subject of scale, this analysis finds that the level at which failure occurs is likely to determine the degree of change that can be achieved. Failures at the policy-level are most likely to merely lead to changes to the tools and instruments used by policy makers. This research thus suggests that failures on the polity- and political level may be required to achieve transformative changes to existing power structures, belief-systems and paradigms. Finally, this research briefly touches on the role of actor and agency in the governance of sustainabilitytransformations through failure and decline. It finds that actors may play an important role in causing a system or one of its elements to fail and in shaping the way events are come to be perceived.
Social insects like honeybees (Apis mellifera) and stingless bees (Apidae: Meliponini) face a relatively high risk to be attacked by pests and pathogens. To decrease the risk of infection, in addition to an innate immune system, these species have evolved various cooperative defense mechanisms which contribute to the overall health of the colonies and are therefore also referred to as social immunity. The collection and use of plant resin is another important strategy of social immunity. Resin is a sticky, often aromatic substance with antimicrobial and deterrent properties secreted by plants for protection of the vegetative tissue. Honeybees and stingless bees take advantage of these properties by using resins for nest construction (often mixtures of resin and wax called "propolis" or "cerumen") and as defense against pests and pathogens. Plant resins, thus, play a crucial role for the ecology of these species and are an important resource for them. Nevertheless, how bees exploit available resin sources and if resin collection can protect colonies from diseases received comparatively little attention in the past. Therefore the aim of this thesis is to provide new insights into the plant origin and significance as well as the influence of resin resource diversity on bee colony health. For honeybees (A. mellifera) in temperate regions, precise information about which resin sources they use is largely lacking. By chemical comparing bee-collected resins and tree resins, the researcher traced back the resin sources used by individual bees. Results show that honeybees collect distinct resin types that are related to different tree species (several poplar species: Populus balsamifera, P. xcanadensis; Betula alba; Aesculus hippocastanum; several poplar species). With this study, the author provided the first evidence, that A. mellifera in temperate regions use a variety of different tree species as resin sources and, moreover, show preferences for specific resin sources. Furthermore, the researcher conducted an experimental field study in which she investigated whether propolis, as it is naturally deposited in the nests, can protect honeybee colonies against some of the most important pathogens (Varroa destructor mite, Deformed Wing Virus). The results of this study showed that propolis in (semi-) natural conditions can increase the disease resistance of honeybee colonies, underscoring the importance of resins for honeybee health. Resin collection by stingless bees is comparatively well studied and it is known that these species commonly forage on a variety of different plant species. To increase knowledge on whether and how bees may profit from a diversity of resin resources, the researcheer tested how the protective function of a resin varied among different sources (and their mixtures) and various potential aggressors (predators, parasites and pathogens). The results of this study revealed that resins from different trees vary in their effectivity against different target organisms. Moreover, resin blends were more effective than some of the individual resins, suggesting that bees can benefit from a variety of resin resources. In summary, honeybees in temperate regions, similar to tropical stingless bees, use a variety of different tree species as resin sources. Because resins from different tree species varied in their protective function, this indicates that bees can profit from a variety of different resins/resin sources by improving the defense against diverse pests and pathogens. Conversely, the lack of resin had a negative impact on the disease resistance of colonies. Consequently, availability as well as the variety of suitable resin sources is of great importance for the health of bees.
To improve the properties of thermochemical heat storage materials, salt mixtures were evaluated for their heat storage capacity and cycle stability as part of the innovation incubator project "Thermochemical battery" of the Leuphana university Lüneburg. Based on naturally occurring compound minerals, 16 sulfates, 18 chlorides and 5 chloride multi-mixtures, 18 bromides and 5 intermixtures between sulfates, chlorides and bromides were synthesized either from liquid solution or by dry mixing for TGA/DSC screening before continuing the heat storage evaluation with five different measurement setups at a laboratory scale. The TGA/DSC analysis served as a screening process to reduce the number of testing materials for the upscaled experiments. The evaluation process consisted of a three-cycle dehydration/hydration measurement at Tmax=100°C and Tmax=200°C. In case of the bromide samples a measurement of hydration conditions with Tmax=110°C and a water flow at e=18.68mbar, were added to the procedure to detect the maximum water uptake temperature. Also, a single dehydration to a temperature of Tmax=500°C was implemented to observe melting behavior and to easier calculate the samples’ stages of hydration from the remaining anhydrous mass. Materials which showed high energy storage density and improved cycle stability during this first evaluation were cleared for multi-cycle measurements of 10 to 25 dehydration and hydration cycles at Tmax = 100 to 120°C and the evaluations at m=20 to 100g scale. An estimate for the specific heat capacities at different temperatures of the materials which passed the initial stage was calculated from the TGA/DSC results as well. The laboratory scale measurement setup went through five stages of refining, which led to reducing the intended maximum sample mass from m=100g to m=20g. A switch from supplied liquid water to water vapor as the used reactant was also implemented in exchange for improved dehydration conditions. Introducing a vacuum pump for evaporating the water limited the influence of outside heat sources during hydration and in-situ dehydration was enabled as to not disturb the state the samples were settling in between measurements. Baseline calculation from blanc measurements with glass powder and attempts to calculate the specific heat capacity cp of the tested materials by 6 applying the Joule-Lenz-law to the measurement apparatus was another step of method development. The evaluation process of the laboratory scale tests at the final setting consisted of 1 to 5 cycle measurements of in-situ dehydration and hydrations with applied vacuum for t=30 minutes at p~30mbar. Upscaling the sample mass to m=20g allowed for a close observation of different material behaviors. Agglomeration, melting and dissolving of the m=10mg samples during the TGA/DSC analysis can be deducted from the recorded measurement curves and the state of the sample after measurement. However, at laboratory scale the visible volume changes, observed sample consistency after agglomeration and an automatic removal of molten and dissolved sample mass during the measurement allowed for a better characterization and understanding of the magnitude of the actual changes. This was done for the first time, particularly for mixed salts. Of the original number of 62 samples, 4 mixtures which passed the initial TGA/DSC screening namely {2MgCl2+ KCl}, {2MgCl2+CaCl2}, {5SrBr2+8CaCl2} and {2ZnCl2 + CaCl2} were chosen for further evaluation. The multi-cycle TGA/DSC measurements of {2MgCl2+ KCl}, {2MgCl2+CaCl2} and {5SrBr2+8CaCl2} showed an improved cycle stability for all three materials over the untreated educts. Of the four materials {2ZnCl2 + CaCl2} displayed the strongest deliquescence during hydration in the upscaled experimental setup. {2MgCl2+CaCl2} proved to be the most stable material regarding the heat storage density. The {MgCl2} content of the mixture is likely to partially or completely react to {Mg(OH)Cl} at temperatures of T>110°C, which however does not impede the heat storage density. {5SrBr2+8CaCl2} displayed a low melting point in hydrated state, causing a fast material loss. This makes it an undesirable storage material. A lower heating rate may still help to avoid an early melting. The {2MgCl2+KCl} mixture was the most temperature stable of the mixtures showing no melting or dissolving behavior. A reaction of the {MgCl2} component of the mixture to {Mg(OH)Cl} was not observed within the applied temperature range of T=25 to 200°C.
Tropical ecosystems are critical for biodiversity conservation and local people’s livelihood sustenance. However, these ecosystems are under high pressure from land-use and land cover (LULC) change, which is further projected to intensify and increase rapidly, thereby affecting biodiversity and the provisioning of vital ecosystem services (ES). It is thus important to understand how LULC might change in the future and how such changes could affect biodiversity and ES provisioning in a given landscape of tropical ecosystems. Scenario planning has become an increasingly popular tool and technique to produce narrative scenarios of the future landscape change. Thus, quantifying changes under different land-use scenarios could be a means to elucidate the synergies and trade-offs within the scenarios. In this dissertation, the author examines the future of biodiversity and ES provisioning for different plausible land-use scenarios in southwestern Ethiopia. First, he translates four future plausible narrative social-ecological land-use scenarios ("Gain over grain", "Coffee and conservation", "Mining green gold" and "Food first") developed for southwestern Ethiopia by participatory scenario planning into spatially explicit LULC scenario maps. Results showed distinct LULC changes under each scenario. Second, the author investigates the impact of these land-use scenarios on biodiversity by specifically modelling woody plant species richness in farmland and forest. Both indicators of human disturbance and environmental conditions were used. Third, he also investigates the effect of these land-use scenarios on woody plant-based ES provisioning by combining woody plant species with household surveys on how woody plants were used by the local community. He models and predicts the current and future availability of woody plant-based ES under the four scenarios of landscape change. Overall, the findings of this dissertation show the importance of integrating future land-use mapping with participatory, narrative-based scenarios to assess the social-ecological outcomes of alternative futures. The spatially explicit maps of LULC change, biodiversity and ES (at different scales) could be used as a valuable input to support stakeholders and decision-makers to weigh the advantages and disadvantages of different development trajectories on ecosystems and human well-being and to avoid or minimize future undesirable consequences. To this end, apart from the benefits of coffee production under "Mining green gold" and crop production under "Food first" scenarios, the findings under these scenarios of large-scale agricultural intensification point to a potentially high loss of biodiversity and ES. These two scenarios could have a negative long-term impact on ecosystems and human well-being. Finally, the "Coffee and conservation" scenario, which involves the creation of a new biosphere reserve, appears to be the most sustainable scenario. This scenario could result in a sustainably managed, diversified landscape which could make major contributions to biodiversity conservation and human well-being in the region and beyond.
Climate change and atmospheric deposition of nitrogen affect biodiversity patterns and functions of forest ecosystems worldwide. Many studies have quantified tree growth responses to single global change drivers, but less is known about the interaction effects of these drivers at the plant and ecosystem level. In the present study, the authors conducted a full-factorial greenhouse experiment to analyse single and combined effects of nitrogen fertilization (N treatment) and drought (D treatment) on 16 morphological and chemical response variables of one-year-old Fagus sylvatica seedlings originating from eight different seed families from the Cantabrian Mountains (NW Spain). Drought exerted the strongest effect on response variables, reflected by decreasing biomass production. However, D and N treatments interacted for some of the response variables, indicating that N fertilization has the potential to strengthen the negative effects of drought (with both antagonistic and amplifying interactions). For example, combined effects of N and D treatments caused a sevenfold increase of necrotic leaf biomass. The authors hypothesize that increasing drought sensitivity was mainly attributable to a significant reduction of the root biomass in combined N and D treatments, limiting the plants' capability to satisfy their water demands. Significant seed family effects and interactions of seed family with N and D treatments across response variables suggest a high within-population genetic variability. In conclusion, the findings indicated a high drought sensitivity of Cantabrian beech populations, but also interaction effects of N and D on growth responses of beech seedlings.
Das Promotionsprojekt, das in das Forschungsprojekt Nawi-In (Naturwissenschaftlichen Unterricht inklusiv gestalten – Kompetenzentwicklung von Lehramtsstudierenden für und mit der Praxis) eingebettet ist, fokussiert die Entwicklung von Analysekompetenzen Masterstudierender der Sekundarstufe I mit naturwissenschaftlichem Fach, inklusiven naturwissenschaftlichen Unterricht zu identifizieren und zu analysieren. Hierfür analysierten die Masterstudierenden (N=5) sowohl eigenen videografierten als auch fremden inklusiven naturwissenschaftlichen Unterricht im Rahmen eines dreisemestrigen Projektseminars. Die Begleitforschung, die im ersten und zweiten Semester des Projektseminars stattfand, untersuchte die Entwicklung der Merkmalsausprägungen der Selbstwirksamkeit, Einstellungen und des selbsteingeschätzten fachdidaktischen Wissens (PCK) in Bezug zu inklusivem naturwissenschaftlichen Unterricht. Der Kern der Forschung ist die Entwicklung eines Modells, um die video-stimulierten Reflexionen zum eigenen (pre und post) und fremden inklusiven naturwissenschaftlichen Unterricht (pre, re und post), die audiografiert und transkribiert wurden, auszuwerten und so eine Entwicklung der Analysekompetenzen über die verschiedenen Erhebungszeitpunkte hinweg feststellen und abbilden zu können. Das Analytical Competency Model (ACM) ist ein Kategoriensystem, das aus verschiedenen Forschungen zu Professionalisierung, Expertiseforschung über Lehrpersonen und professioneller Unterrichtswahrnehmung besteht. Validiert wurde das ACM durch das Erstellen eines Expertenratings. Die Ergebnisse zeigen eine deutliche Entwicklung der Analysekompetenzen in der Studierendenstichprobe. Es wurden über den Erhebungszeitraum hinweg mehr Momente als inklusiver naturwissenschaftlicher Unterricht identifiziert und die identifizierten Momente in übergeordnete Konzepte zu inklusivem naturwissenschaftlichen Unterricht eingeordnet.
The overall aim of this thesis is to develop empirical probabilistic frameworks that help to quantify the impacts of temporal and spatial scale dependencies and model uncertainties of climate projections regarding precipitation-dependent parameters. The thesis is structured in four articles. Article one is the first study that analyzed climate projections from the spatially highly resolved regional climate model (RCM) ensemble EURO-CORDEX. Additionally, the significance and the robustness of the projected changes are analyzed, and improvements related to the higher horizontal resolution of the new data set are discussed. A major finding is, that RCM simulations provide higher daily precipitation intensities, which are missing in the global climate model (GCM) simulations, and that they show a significantly different climate change of daily precipitation intensities with a smoother shift from low towards high intensities. The second article elaborates on impacts of temporal and spatial aggregation on extreme precipitation intensities. By combining radar data with cloud observations, the different temporal and spatial scaling behavior of stratiform and convective type precipitation events can be analyzed for the first time. The separation between convective and stratiform type events also allows to quantify the contribution of convective events to the extremes. Further, it is shown that temporal averaging has similar effects on the precipitation distribution as spatial averaging. Associated pairs of temporal and spatial resolutions that show comparable intensity distributions are identified. Using precipitation data from radar observations, a gauge station network and a spatially highly resolved regional climate model, the third paper optimizes the process that finds associated temporal and spatial scales (see second article). This information is used to develop a method that adjusts point measurements to the temporal and spatial scale of a previously defined model grid. The study shows that this procedure can be used to improve bias-adjustment methods in areas with a low gauge station density. It is known that the EURO-CORDEX ensemble overestimates precipitation and shows a common cold bias in the Alpine region. The fourth article evaluates how these biases are changing the temperature distribution and the temperature dependency of precipitation-frequencies. These biases are a source of uncertainty that is not captured by the robustness tests performed in the first article. A probabilistic-decomposition-framework is developed to quantify the impact of these biases on precipitation-frequency changes and to investigate causes for the ensemble spread.
Seit den frühen 1990er Jahren wird transdisziplinäre Nachhaltigkeitsforschung in Form von problemorientierten Forschungs- und Lernprojekten konzeptioniert und praktisch umgesetzt, an denen außeruniversitäre Akteuren beteiligt sind. Diese Forschungsarbeit verfolgt drei Ziele: Erstens, die Konzeptualisierung der Begriffe Kultur, Multi-, Inter- und Transkulturalität in der Literatur zur transdisziplinären Nachhaltigkeitsforschung zu untersuchen. Zweitens, die Konzeptionierung und Umsetzung von transdisziplinären Forschungs- und Lernprojekten in Hinblick auf kulturelles Differenzieren zu analysieren. Drittens, konzeptionelle Beiträge zur Gestaltung von transdisziplinären Forschungs- und Lernprojekten zu entwickeln. Methodisch wird auf Literaturanalysen und eine qualitative Untersuchung zweier transdisziplinärer Lernforschungsprojekte zurückgegriffen. Unter dem Begriff Forschungs- und Lernprojekt werden in dieser Forschungsarbeit sowohl Forschungsprojekte als auch Lehr-Lernforschungsprojekte gefasst. Zentrale Ergebnisse der Forschungsarbeit sind die Folgenden: Erstens wird der Kulturbegriff in der transdisziplinären Nachhaltigkeitsforschung zwar vielfältig verwendet, als Forschungsthema, Hintergrund von Beteiligten, Kooperationsweise, Projektkontext, in Hinblick auf Interkulturalität oder als Wissenskultur, allerdings kaum ausdifferenziert und konkretisiert. Zweitens besteht auf der Ebene der Konzeptionierung von transdisziplinären Forschungs- und Lernprojekten: 1) ein starkes Übergewicht von Integration und Konsens gegenüber einer Auseinandersetzung mit Differenz, 2) eine implizite Vorauswahl von Beteiligten durch bestimmte Begrifflichkeiten und methodologische Ansätze und 3) eine Reproduktion von Machtverhältnissen durch (dichotome) Symmetrie- und Ausgleichsvorstellungen. Drittens zeigt sich auf der Ebene der Umsetzung von Lernforschungsprojekten: 1) eine starke Prozessorientierung der Projekte, 2) ein Spannungsfeld zwischen einer Öffnung und Steuerung in Hinblick auf den Projektverlauf und 3) vielfältige Differenzaushandlungen in Interaktionen (wie Zeitlichkeit, Verantwortung, Erfahrung, Relevanz). Die Ergebnisse zeigen, dass politische Implikationen der Forschung und zentrale Ungleichheitskategorien der Kultur- und Sozialwissenschaften (u.a. race, class, gender, body) kaum thematisiert werden. Vorschläge zur Gestaltung transdisziplinärer Forschungs- und Lernprojekte werden in Hinblick auf ein Verständnis von Forschungsdesigns als Prozesse, einem Erkunden von Differenzierungen und Forscherpositionen und der Bedeutung eines Verlernens entwickelt.
Um das noch bestehende Reichweitenproblem von Elektrofahrzeugen zu lösen, sind Fahrzeugkonzepte wie Plug-in Hybridfahrzeuge sehr vielversprechend, sofern mit ihm überwiegend im Batteriebetrieb gefahren wird. Sie kombinieren die Vorteile des Verbrennungsmotors und des Elektromotors, sodass das lokale Emissionsproblem in Ballungszentren gelöst werden kann, ohne dass der Kunde dabei auf die Reichweite verzichten muss. Wenn das Fahrzeug allerdings überwiegend für Kurzstrecken genutzt wird, sind alterungsbedingte Veränderungen des Kraftstoffes möglich, da dieser länger im Tank verbleibt als üblich. In dieser Arbeit wird ein Konzept zur sensorischen Bestimmung der Qualität des Kraftstoffes vorgestellt. Hierzu wurde ein Prototyp entwickelt, in dem mithilfe des Real- und Imaginärteils der Permittivität alternde Kraftstoffe erkannt werden können. Dabei konnte durch das frequenzabhängige Permittivitätssignal des Sensors spezifisch zwischen nieder- und hochmolekularen Oxidationsprodukten in Kraftstoffen unterschieden werden. Da das Verbrennungs- und Emissionsverhalten des Motors von der Kraftstoffmischung vorgegeben ist, bietet eine zusätzliche sensorische Erfassung der Kraftstoffzusammensetzung weitere Optimierungspotenziale, um Emissionen zu reduzieren: So ist das Motormanagement im Fahrzeug zumeist auf Referenzkraftstoffe mit gleichbleibender Qualität abgestimmt. Variable Kraftstoffzusammensetzungen, die durch die Erdöllagerstätte und den zusätzlichen Konversionsverfahren zur Herstellung von fortschrittlichen Kraftstoffen vorgegeben sind, werden in dieser Anpassungsstrategie bisher nicht berücksichtigt. Als weitere Aufgabe wird in dieser Arbeit daher ein multisensorischer Ansatz verfolgt, wonach zusätzlich zur Kraftstoffalterung noch die Kraftstoffzusammensetzung erkannt werden kann. Insgesamt bietet die Sensorik das Potenzial zur kontinuierlichen Kraftstoffüberwachung in Plug-in Hybridfahrzeugen, um so einen Beitrag zum sicheren und nachhaltigen Betrieb solcher Fahrzeuge gewährleisten zu können.
Nachhaltigkeitsziele im Sinne einer Ökologie, Ökonomie und Soziokultur lassen sich im Bauwesen auf verschiedene Instrumente zurückführen. Optimierung des Wärmeschutzes durch die Energieeinsparverordnung (Effizienz) oder Minimierung von Abfall im Kreislaufwirtschaftsgesetz (Suffizienz). Um jedoch eine neue Qualität der Nachhaltigkeit zu schaffen, ist ein Paradigmenwechsel notwendig. Dabei können Cradle to Cradle Prinzipien als ökoeffektive Methode angewandt werden, in dem exemplarisch die Biodiversität eingebunden, gesunde Bauprodukte verbaut und erneuerbare Energien genutzt werden. Die Natur dient als Vorbild (Konsistenz). Demnach werden Gebäude nützlich für Mensch, Umwelt und Gesellschaft umgesetzt und gleichzeitig Werte geschaffen. Für den deutschen Einzelhandel bestehen vielschichtige Potenziale, da der Gebäudebestand mit mehreren Millionen Quadratmetern bedeutend ist und die Bauwerke aufgrund von Konzeptänderungen oder Verschleiß der Ladenflächen regelmäßig umgebaut werden. Die Forschung beginnt mit einer Bestandsaufnahme von Cradle to Cradle Bauprodukten und Analyse eines real umgesetzten Einkaufszentrums. Um Einflussfaktoren von Stakeholdern zu identifizieren, wurden qualitative Experteninterviews mit ausgewählten Projektbeteiligten aus Bauherrn, Betreibern, Beratern, Mietparteien und Herstellern durchgeführt. Im Rahmen des Forschungsvorhabens wurde untersucht, inwieweit sich Bauprodukte aus der Gebäudeplanung in wissenschaftlicher Theorie und praktischer Bauwirtschaft umsetzen lassen, Geschäftsmodelle anwendbar sind, Trends und Innovationen im Zusammenhang stehen oder Änderungen in Politik oder Wirtschaft notwendig sind. Im Ergebnis wurden Maßnahmen für eine neue Qualität der Nachhaltigkeit bei Einzelhandelsgebäuden identifiziert. Exemplarisch wird anhand der Interviews deutlich, dass neben einem staatlichen Umweltzeichen oder einer Green Building Planungsdisziplin, insbesondere die Ökonomie in Form von Investitions- und Betriebskosten den größten Stellenwert besitzt. Es braucht einen staatlichen Regulierungsrahmen und neue Geschäftsmodelle, damit nachhaltige Bauprodukte wirtschaftlich werden und durch Stakeholder in den Prozessen der Planung, Bauausführung und dem Betrieb berücksichtigt werden.
Over the past two decades, transitions research has witnessed rapid development. However, there is still a notable gap in our understanding of sustainability transitions in conflict settings and the role of international organizations in these transitions. Little is known about the dynamics of power, limiting and facilitating factors, and the role of (international) actors in sustainability transitions in conflict settings. This dissertation seeks to make contributions to these discussions by examining energy transitions in Afghanistan, a conflict-affected country, between 2001 and 2021. It specifically focuses on the involvement of international development organizations, shedding light on their role in energy access, institutional change, and imagining Afghanistan's future energy system development. After security, access to affordable energy is frequently reported to be Afghanistan's most pressing need. Following the fall of the first Taliban regime in 2001, billions of dollars and dozens of international development organizations poured into Afghanistan to support the reconstruction of the country including its energy sector. Between 2001 and 2021, the government of Afghanistan and the international development organizations worked on various aspects of energy system development despite on-going insurgency and threats against infrastructural projects. In 2021, the Taliban regained power, resulting in the suspension of operations for most development organizations, with only a few humanitarian agencies remaining active. Within this context, this thesis explores topics such as the country's energy potential and policy, the role of international development organizations in the energy sector, and visions for a future energy system in Afghanistan. The research conducted for this thesis employed a qualitative case study approach, utilizing semi-structured interviews and document analysis.
Sustainable landscape development is the main goal of decision makers worldwide. Achieving this goal in the long term leads to achieving social, economic and environmental sustainability. Remote sensing has been playing an essential role in monitoring remote areas. This study has employed part of the role of remote sensing in supporting the direction of decision makers towards sustainable landscape development. The study has focused on some of the main elements affecting sustainable environment: land uses, specifically agricultural land uses, water quality, forests, and water hazards such as floods. Three research programs were undertaken to investigate the role of Terrasar-x imagery, as a source of remote sensing data, in monitoring the environment and achieving the previous stated elements. The investigation was intended to investigate the effectiveness of TSX imagery in identifying the cropping pattern of selected study areas by employing a pixel-based supervised maximum likelihood classifier, as published in Paper I, assessment of the efficiency of using TSX imagery in determining land use and the flood risk maps by applying an object-based decision tree classifier as published in Paper II, and determination of the potential of inferential statistics tests such as the two samples Z-test and multivariate analysis, for example Factor Analysis, for identifying the kind of forest canopy, based on the backscattering coefficient of TSX imagery of forest plots, as presented in Paper III. Papers I and II covered two pilot areas in the Lower Saxonian Elbe Valley Biosphere Reserve “das Biosphärenreservat "Niedersächsische Elbtalaue" around Walmsburger Werder and Wehninger Werder. Paper III focused on the Fuhrberger Feld water protection area near Hanover in Germany. The inputs for this research were mainly SAR Imagery and the ground truth data collected from field surveys, in addition to databases, geo-databases and maps. The study presented in Paper I used two filters to decrease speckle noise namely De-Grandi as multi-temporal speckle filter, and Lee as an adaptive filter. A multi-temporal classification method was used to identify the different crops using a pixel-based maximum likelihood classifier. The classification accuracy was assessed based on the external user accuracy for each crop, the external producer accuracy for each crop, the Kappa index and the external total accuracy for the entire classification. Three cropping pattern maps were produced namely the cropping pattern map of Wehninger Werder in 2011 and the cropping pattern maps of Walmsburger Werder in 2010 and in 2011. The study showed that image filtering was essential for enhancing the accuracy of crop classification. The multi-temporal filter De-Grandi enhanced the producer accuracy by about 10% compared to the Lee filter. Furthermore, gathering and utilizing large ground truth data greatly enhanced the accuracy of the classification. The research verified that using sequence images covering the growing season usually improved the classification results. The results exposed the effect of the polarization and demonstrate that the majority of the classifications produced according to the crop calendar had higher total producer accuracy than using all acquisitions. The study demonstrated undertaken in Paper II applied the decision tree object-based classifier in determining the major land uses and the inundation extent areas in 2011 and 2013 using the Lee-filtered imagery. Based on the maps produced for the land uses and inundation areas, the hazard areas due to the floods in 2011 and 2013 were identified. The study illustrated that 95% of the inundated area was classified correctly, that 90% of vegetated lands were accurately determined, and around 80% of the forest and the residential areas were correctly recognized. The research undertaken in Paper III statistically analyzed the backscattering coefficient of the Lee-filtered TSX in some forest plots by the Factor Analysis and two sample Z-test. The study showed that Factor analysis tools succeeded in differentiating between the coniferous forest and the deciduous forest and mixed forest, but failed to discriminate between the deciduous and the mixed forest. On one hand, only one factor was extracted for each sample plot of the coniferous forest with approximately equal loadings during the whole acquisition period from March 2008 to January 2009. On the other hand, two factors were extracted for each deciduous or mixed forest sample plot, where one factor had high loadings during the leaf-on period from May to October, and the other one had high loadings during the leaf-off period from November to April. Furthermore, the research revealed that the two sample Z-test enabled not only differentiation between the deciduous and the mixed forest against the coniferous forest, but also discrimination between deciduous forest and the mixed forest. Statistically significant differences were observed between the mean backscatter values of the HH-polarized acquisitions for the deciduous forest and the mixed forest during the leaf-off period, but no statistically significant difference was found during the leaf-on period. Moreover, plot samples for the deciduous forest had slightly higher mean backscattering coefficients than those for the mixed forest during the leaf-off period.
Gegenwärtige atmogene N-Einträge in die Lüneburger Heide überschreiten die durch den critical-load für Sandheiden definierte Belastungsgrenze von 10-20 kg ha-1 und zeigen den Handlungsbedarf für eine langfristige Erhaltung dieser geschützten Lebensräume. Die traditionelle Schafbeweidung im NSG Lüneburger Heide kann diese hohen atmogenen N-Einträge kompensieren. Das Herdenmanagement minimiert den Nährstoffeintrag über die Exkremente der Tiere, so dass diesem Transfer nur eine geringe Bedeutung zukommt. Die N-Austräge über das Sickerwasser vor, während und nach den Pflegemaßnahmen spielen nur eine untergeordnete Rolle. Extensive Pflegemaßnahmen wie die Mahd und das kontrollierte Brennen sind nicht geeignet die atmogenen N-Einträge langfristig zu kompensieren. Intensiven Pflegemaßnahmen (Schoppern, Plaggen) gelingt dieses, benötigen aber einen zu langen Bearbeitungszyklus, innerhalb dessen kombinierte Verjüngungsmaßnahmen notwenig werden. Die Pflegemaßnahmen haben Auswirkungen auf die N- und P-Vorräte im Heidesystem und führen großteils zu einer P-Verarmung. Das kontrollierte Brennen beeinflusst den P-Haushalt am geringsten. Eine Kombination des Feuereinsatzes mit anderen extensiven Maßnahmen erscheint daher sinnvoll.
It is understood among research and policy makers that addressing unsustainable individual consumption patterns is key for the vision of sustainable development. Education for Sustainable Consumption (ESC) is attributed a pivotal role for this purpose, aiming to improve the capacity of individuals to connect to and act upon knowledge, values and skills in order to respond successfully and purposefully to the demands of sustainable consumption. Yet despite political, scientific, and educational efforts and increasing awareness in the general population, little has been achieved to substantially change behavioral patterns so far. As part of the explanation for this shortcoming, it has been argued that current ESC practices have neglected the personal dimension of sustainable consumption, especially the affective-motivational processes underlying unsustainable consumption patterns. Against this background, this cumulative thesis is guided by the question how personal competencies for sustainable consumption can be defined, observed, and developed within educational settings. Special attention is given to mindfulness practices, describing the practice of cultivating a deliberate, unbiased and openhearted awareness of perceptible experience in the present moment. Drawing upon an explorative, qualitative research methodology, the thesis looks at three different mindfulness-based interventions aiming to stimulate competencies for sustainable consumption, reaching out to a total number of 321 participants (employees and university students). In this thesis, the author suggests to define personal competencies for sustainable consumption as abilities, proficiencies, or skills related to inner states and processes that can be considered necessary or sufficient to engage with sustainable consumption (SC). These include ethics, self-awareness, emotional resilience, selfcare, access to and cultivation of personal resources, access to and cultivation of ethical qualities, and mindsets for sustainability. The thesis holds that the observation of personal competencies benefits from a combination of different methodological and methodical angles. When working with self-reports as empirical data, a pluralistic qualitative methods approach can help overcoming shortcomings that are specifically related to individual methods while increasing the self-reflexivity of the research. Moreover, it is suggested to let learners analyze their own personal statements in groups, applying scientific methods. The products of the group analyses represent data based on an inter-subjectively shared perspective of learners that goes beyond self-estimation of personal competencies. In terms of developing personal competencies for SC, it can be concluded that mindfulness practice alone is not sufficient to build personal competencies for SC. While it can stimulate generic personal competencies, individuals do not necessarily apply these competencies within the domain of their consumption. Nevertheless, mindfulness practice can play an important role in ESC, insofar as it lays the inner foundation to engage with sustainability-related issues. More precisely, it allows learners to experience the relevance of their inner states and processes and the influence they have on actual behaviors, leading to a level of selfawareness that would not be accessible solely through discursive-intellectual means. Furthermore, participants experience mindfulness practice as a way to develop ethical qualities and access psychological resources, entailing stronger emotional resilience and improved well-being. In order to unleash its full potential for stimulating personal competencies for SC, however, the findings of the thesis suggest that mindfulness practice should be (a) complemented with methodically controlled self-inquiry and (b) related to a specific behavioral change. In this vein, self-inquiry-based and self-experience-based learning – two pedagogical approaches developed during the period of research for this thesis – turned out to be promising pedagogies for educational settings striving to stimulate the development of personal competencies for SC.
Increasingly, researchers are expected to work in collaborative interdisciplinary teams to tackle more complex and interrelated problems. However, the prospect of collaborating with others, from different disciplines, exerts countervailing forces on researchers. There is the lure of transcending the limitations of one's own knowledge, methods and conventions, belonging to diverse intellectual communities and tackling, together, ambitious research topics. On the other hand, there is the risk that collaborating across disciplinary boundaries will be taxing, confounding at times, with no guarantee of success. This thesis is about collaborative interdisciplinary research from the perspective of a formative accompanying researcher. The author accompanied an interdisciplinary research team in the field of sustainability over three years for the duration of a collaborative project. Formative accompanying research (FAR) is an approach to "research into research" that learns about, with and for a collaborative interdisciplinary team. The author found - through immersion in the literature, her own daily experiences of collaborating, and her observations – that interdisciplinary collaboration is very difficult. It requires a basic understanding and appreciation of other disciplines and methods, as well as the skills to integrate research inquiries and findings across diverse epistemologies. It also requires awareness that collaborative interdisciplinary research is more than an intellectual task of knowledge creation. Other factors matter, such as interpersonal relationships, power differentials, different research tempos and a sense of belonging. And these factors have an impact on processes and outcomes of collaborative knowledge creation. Knowing this implies a willingness to keep learning and to tolerate discomfort so as to cultivate deeper levels of collaborative capacity. The author discovered that in these deeper levels lie skills for staying with inevitable tensions, for talking and listening to generate new understanding together, and for applying a researcher's frank curiosity to oneself too. A formative accompanying researcher, who is part of the team she is researching, has to navigate delicate terrain. In this thesis, the author develops a FAR methodology that takes seriously the questions of positionality and relationality, and reflects on the experiences of putting these into practice. A FAR practice involves remaining in dynamic movement between observing and participating, between exercising curiosity and care, and between the researchers' own sense of impartiality and investment in relation to the issues at hand. There is merit in furthering the methodology and practice of FAR on its own terms. This includes attending to the skills required by a formative accompanying researcher to remain oriented within the concentric circles of research, relationship and loyalty that make up a collaborative team. There is also the question of how FAR, and other forms of research into research, can help to advance collaborative interdisciplinary research. The author argues for creating the conditions in research teams that would enable treating collaboration as a capacity to develop, and that would facilitate team members' receptivity to learning with FAR. Furthermore, she explores dilemmas of intervening as a formative accompanying researcher and of sustaining dynamic positionality over the long-term.
Vocational Integration of Refugees - Chances and Challenges of Refugee (Social) Entrepreneurship
(2019)
In recent years, especially since 2015, Germany and other European countries have accepted high numbers of refugees. The social and vocational integration of these refugees and of those yet to come represents a challenge. (Social) entrepreneurship is one means to achieve this goal, to fully tap into the potential of refugees and to give them a chance to make a living in host countries. This dissertation examines the potential of vocational integration of refugees through (social) entrepreneurial activities. It includes a detailed literature review and suggests possible direction in the emerging field of refugee (social) entrepreneurship. This dissertation shows that to foster refugee (social) entrepreneurship, the identification and evaluation of specific and potential needs for support is essential. Incubators in particular have a high potential for supporting refugee entrepreneurs, in part it is possible for them to address some of the challenges faced by this target group, which differ from those of locals or migrant entrepreneurs. More specifically, this dissertation aims to answer two research questions: (1) What are relevant (social) entrepreneurial concepts that can contribute to the vocational integration of refugees? (2) What are the distinct contributions of and challenges faced by refugees when it comes to their vocational integration through (social) entrepreneurial activities? Analyzing select practical cases, this dissertation has several important implications for researchers who seek to bridge the gap between academia and society in the context of refugee entrepreneurship and refugee social entrepreneurship research. The findings presented here are also relevant for practitioners, for example those working at business incubators, who aim to facilitate the vocational and social integration of refugees in general and refugees with entrepreneurial aspirations in particular.
The research aims to assess the sustainability of rural electrification efforts based on off-grid photovoltaic (PV) systems in three Andean countries: Chile, Ecuador, and Peru. Although deployment of off-grid PV solutions for rural electrification began in the early 1990s in the Andean region, most of the projects turned out to be unsustainable and did not last. Prior efforts have addressed the different issues and barriers that plagued these projects and inhibited their sustainability. However, these prior analyses were mostly quantitative; systematic qualitative evaluations have been scarce. In this thesis, the researcher addresses the following research question: "Are the rural electrification programs (based on off-grid PV Systems) in the Andean countries sustainable?" In order to answer this research question, he conducted an exhaustive qualitative document analysis complemented by semi-structured expert interviews. The interviewees included experts from different ministries, project managers from leading Non-Governmental Organizations (NGOs), public and private companies ' representatives, supervisors, and researchers. Although the author also describes several relevant PV-based electrification efforts in the Andean countries, the research was aimed at providing an overall picture of the rural electrification efforts in these countries, rather than measuring the success or failure of specific projects. The gathered information allowed me to assess the sustainability of rural electrification efforts in the Andean countries. This assessment was based on a set of indicators corresponding to the four dimensions of sustainability considered in this thesis: institutional, economical, environmental, and socio-cultural. It was found that Ecuador and Chile have consistently failed to ensure mechanisms for the operation and maintenance of the deployed off-grid systems, which has made these solutions in poor Chilean and Ecuadorian communities inevitably unsustainable. Although Peru has adopted a cross-tariff scheme, the Peruvian case shows that ensuring the funding of off-grid PV solutions is not enough. Peruvian officials appear to be unaware of the importance of local participation (local values and lifestyles are constantly disregarded) and most of the projects have been designed without the participation and engagement of the communities, which has often led to project failures and payment defaults. Although each country has its particular challenges, it was found that the three Andean countries have consistently neglected the importance of strong formal institutions with a flexible and decentralized structure, which in turn significantly compromised the rural electrification effort in these countries.
Zur Ermittlung der Belastung der Elbe mit Pestiziden wurden chemische Analyseverfahren entwickelt, wobei das untersuchte Stoffspektrum insgesamt 106 Analyte umfasste. Die Untersuchungen ermöglichten 1989 eine erstmalige Identifizierung und Quantifizierung von Pestiziden in hohen Konzentrationen (unterer µg/L-Bereich) im Elbeästuar, nach der Wiedervereinigung deren Rückverfolgung zu industriellen Punktquellen in der ehemaligen DDR (Längsprofile), eine Erfassung der historischen Entwicklung der Belastungssituation in den 90er Jahren, die Feststellung der zunehmenden Bedeutung von Einträgen aus diffusen Quellen im Vergleich zu Punktquellen sowie die Ermittlung des Stoffspektrums und der zeitlichen und örtlichen Variabilität innerhalb eines Zeitraumes von drei Jahren (Monatsmischproben und Zeitreihen an unterschiedlichen Querschnitten der Elbe sowie Längsprofile). Der Fokus richtete sich im weiteren Verlauf auf die Entwicklung chemischer Analyseverfahren zur sicheren Identifizierung und Quantifizierung von Wirkstoffen mit niedrigen Qualitätszielen/-kriterien (unterer ng/L- bzw. sub-ng/L-Bereich). Zur Bewertung der Belastungssituation und zur Diskussion von Monitoring-Strategien wurden national und international verfügbare Qualitätsziele/-kriterien insbesondere für die aquatische Lebensgemeinschaft herangezogen.
Protected areas are an essential tool for conserving biodiversity. However, their ecological effectiveness is contested and their capacity to resist human pressures differ. This dissertation aimed to assess the ecological effectiveness of different protection levels (from strict to less strictly protected: national park, game reserve, forest reserve, game-controlled area, and unprotected areas) in biodiversity (both mega diverse butterflies and mammals), maintaining habitat connectivity, and reducing anthropogenic threats at the wider landscape in the Katavi-Rukwa Ecosystem of southwestern Tanzania. To achieve this overarching goal, the researcher employed an interdisciplinary approach. First, he analyzed butterfly diversity and community composition patterns across protection levels in the Katavi-Rukwa Ecosystem. He found that species richness and abundance were highest in the game reserves and game-controlled areas, intermediate in the forest reserves, national park and unprotected areas. Species composition differed significantly among protection levels. Landscape heterogeneity, forest cover, and primary productivity influenced species composition. Land-use, burned areas, forest cover, and primary productivity explained the richness of species and functional traits. Game reserves hosted most indicator species. Second, the author modelled the spatial distribution of six large mammal target species (buffalo Syncerus caffer, elephant Loxodonta africana, giraffe Giraffa camelopardalis, hartebeest Alcelaphus buselaphus, topi Damaliscus korrigum, and zebra Equus burchellii) across environmental and protection gradients in the Katavi-Rukwa Ecosystem. Based on species-specific density surface models, he found relatively consistent effects of protection level and land-use variables on the spatial distribution of the target mammal species: relative densities were highest in the national park and game reserves, intermediate in forest reserves and game-controlled areas and lowest in un-protected areas. Beyond species-specific environmental predictors for relative densities, the results highlight consistent negative associations between relative densities of the target species and distance to cropland and avoidance of areas in proximity to houses. Third, the author examined temporal changes in land-use, population densities and distribution of six large mammal target species across protection levels between 1991 and 2018. During the surveyed period, cropland increased. Wildlife densities of most, but not all target species declined across the entire landscape. Based on logistic regression models, target species preferred the national park over less strictly protection levels and areas distant to cropland. Fourth, he quantified land-use changes, modelled habitat suitability and connectivity of elephant over time across a large protected area network in southwestern Tanzania. Based on analyses of remotely-sensed data, cropland increased from 7% in 2000 to 13% in 2019. Based on ensemble models, distance from cropland influenced survey-specific habitat suitability for elephant the most. Despite cropland expansion, the locations of the modelled elephant corridors (n=10) remained similar throughout the survey period. Based on circuit theory, the author prioritizes three corridors for protected area connectivity. Key indicators of corridor quality varied over time, whereas elephant movement through some corridors appears to have increased over time. Overall, this dissertation underpins differences in ecological effectiveness of protected areas within one ecosystem. It highlights the need to utilize a landscape conservation approach to guide effective conservation across the entire protection gradient. It also suggests the need to enforcing land use plans and having alternative and sustainable forms for generating income from the land without impairing wildlife habitat.
Siliziumorganische Substanzen sind aus dem Alltag kaum wegzudenken. Sie kommen in vielfältiger Form vor und finden durch ihre Stabilität in vielen Produkten des Haushalts und der Industrie Anwendung. Eine Freisetzung in die Umwelt ist unvermeidbar. Siliziumorganische Substanzen konnten bereits in allen Umweltkompartimenten (Luft, Wasser, Boden) analytisch nachgewiesen werden. Welche Risiken von dieser Stoffgruppe ausgehen, ist noch nicht abschließend geklärt. Dennoch gibt es Hinweise auf negative Auswirkungen auf Mensch und Umwelt. Deshalb sollten Strukturen in siliziumorganischen Substanzen untersucht werden, die einen Abbau in der Umwelt begünstigen, um die Akkumulation dieser Stoffe in der Umwelt zu verringern. Dafür wurden diverse biotische und abiotische Abbautests mit unterschiedlichen siliziumorganischen Substanzen durchgeführt. Der Fokus der vorliegenden Arbeit lag vor allem in der biologischen Abbaubarkeit der Substanzen. Es wurden die Organisation for Economic Co-operation and Development (OECD)-konformen Tests Closed-Bottle-Test (CBT, OECD 301D) und Manometrischer Respirationstest (MRT, OECD 301F) durchgeführt. Die Hydrolysierbarkeit wurde mithilfe des Hydrolysetests OECD 111 bei unterschiedlichen pH-Werten untersucht. Bei bestimmten Substanzgruppen ohne biologischen Abbau wurde das Verhalten der Substanzen bei Bestrahlung mit verschiedenen Bestrahlungsquellen untersucht. Die Analyse der Primärelimination der siliziumorganischen Substanzen erfolgte je nach Substanzeigenschaften mithilfe der Hochleistungsflüssigkeitschromatografie gekoppelt mit einem Spektrometer mit ultraviolettem und sichtbarem Licht (HPLC-UV/Vis) oder der Gaschromatografie gekoppelt mit einem Massenspektrometer (GC-MS). Die Transformationsprodukte wurden hingegen mithilfe der Flüssigkeitschromatografie gekoppelt mit einem Mehrfach-Massenspektrometer (LC-MSn) analysiert. Für eine umfassende Bewertung des biologischen Abbaus von siliziumorganischen Substanzen wurden ein Vergleich mit analogen Kohlenstoffverbindungen und eine Aufstockung mit Daten aus der Datenbank der Europäischen Chemikalien Agentur (ECHA) durchgeführt. Die Gruppierung der Substanzen nach ihren Strukturmerkmalen wurde hinzugezogen, um Rückschlüsse auf die Abbaubarkeit zu ziehen. Eine besser biologisch abbaubare Grundstruktur brachte für die Benzenderivate keine Verbesserung der biologischen Abbaubarkeit. Dennoch hatte die Einführung von +M-Gruppen am Aromaten einen positiven Einfluss auf die Geschwindigkeit und den Grad des photolytischen Abbaus. Die Bestrahlungsquelle hatte ebenfalls einen deutlichen Einfluss auf die Eliminierungsrate während des Photolyseexperiments. Mit einer Veränderung der Wellenlängen in den kurzwelligen Bereich und der daraus resultierenden energiereicheren Strahlung konnten die Substanzen schneller und teilweise vollständig primär eliminiert werden. Bei allen Abbaupfaden hatte die Hydrolyse eine entscheidende Rolle und wurde als einer der Hauptabbauprozesse charakterisiert. Bei einer Verbindung wurde im Nachgang an die biotischen und abiotischen Abbautests eine ausführliche Aufklärung der elf gebildeten Transformationsprodukte vorgenommen. Um den Einfluss von Silizium in organischen Substanzen auf die biologische Abbaubarkeit zu untersuchen, wurde der direkte Vergleich von siliziumorganischen Substanzen und deren Kohlenstoffanaloga im CBT durchgeführt. Dabei hat sich gezeigt, dass drei von fünf Kohlenstoffverbindungen und keine siliziumorganische Verbindung als leicht biologisch abbaubar eingestuft werden konnten. In allen bis auf einen Fall konnten für die Kohlenstoffverbindungen höhere Abbauraten im CBT beobachtet werden. Die Hydrolyse wurde als erforderlicher Schritt vor dem biologischen Abbau von siliziumorganischen Substanzen identifiziert. Das siliziumfreie Produkt der Hydrolyse bestimmte den Grad des biologischen Abbaus. Die gute biologische Abbaubarkeit der einen siliziumorganischen Verbindung resultierte aus der leicht hydrolysierbaren Silizium-Stickstoff-Bindung und der leichten biologischen Abbaubarkeit des siliziumfreien Hydrolyseproduktes. Die siliziumhaltigen Reaktionsprodukte der Hydrolyse waren nicht biologisch abbaubar. Bioabbaudaten aus eigenen Experimenten, aus vorhergehenden in der Arbeitsgruppe durchgeführten analogen Arbeiten und aus der ECHA-Datenbank wurden zusammengetragen, um einen Datensatz zu generieren. Die 182 Substanzen des Datensatzes wurden hinsichtlich ihrer Struktur gruppiert, um allgemeine Erkenntnisse für die biologische Abbaubarkeit von siliziumorganischen Verbindungen abzuleiten. Es gab Gruppen mit Substanzen, die überhaupt nicht biologisch abbaubar waren (z. B. zyklische, lineare und verzweigte Siloxane). Gruppen, die Substanzen mit Ethern, Estern, Oximen, Aminen und Amiden enthielten, waren hydrolyseanfällig, sodass auch leicht biologisch abbaubare Zwischenprodukte gebildet werden konnten. Die siliziumfreien Hydrolyseprodukte waren meist biologisch abbaubar, während die siliziumhaltigen Hydrolyseprodukte persistent waren. Allgemein hat sich gezeigt, dass Modifikationen am Molekül einen positiven Einfluss auf die Abbaubarkeit haben können. Beispielsweise können Heteroatome eine Veränderung der Polarität bzw. der Elektronendichte hervorrufen, was die Photolyse- und Hydrolysefähigkeit und folglich auch den Bioabbau zum Positiven verändern kann. Das Einführen solcher Heteroatome oder funktioneller Gruppen in Polysiloxanketten kann demnach ein vielversprechender Ansatz für leichter abbaubare siliziumorganische Verbindungen sein. Nicht abbaubare Stoffe sollten vermieden werden, wenn sie nach ihrer Verwendung in die Umwelt gelangen.