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Institut
Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been widely used since 1950 in various consumer products as well as in industrial applications owing to their unique properties, e.g. being hydrophobic and lipophobic at the same time. Nowadays, some of these persistent and man-made PFASs can ubiquitously be found in humans, wildlife and various environmental media. One prominent representative of concern, belonging to the subgroup of perfluorocarboxylates (PFCs) and their conjugate acids (PFCAs), is perfluorooctanoat (PFO) and its conjugate acid (PFOA). Because of its adverse effects on human health and its persistency in the environment industry has started to replace PFO(A) and related long chain chemicals (with seven and more fully fluorinated carbon atoms) with so-called short chain PFASs (less than seven fully fluorinated carbon atoms), including precursors of PFC(A)s. Also these short chain PFC(A)s are persistent and can already be found in humans, ground- and drinking water and in remote regions. However, knowledge gaps exist in understanding the partitioning and the resulting mobility of short chain PFC(A)s in the environment. This is due to the fact that partitioning data of PFC(A)s from standardised experiments can easily be biased by various artefacts, e.g. self-aggregation of the molecules. Therefore, the objectives of this thesis are (i) to quantify the partitioning of PFC(A)s into mobile environmental media, (ii) to show how results from non-standard tests can be used to assess substance properties of concern and (iii) to conclude on whether the environmental exposure to short chain PFC(A)s is of concern from a regulatory point of view. In the first part of this thesis, the environmental mobility of short chain C4-7-PFC(A)s was investigated by quantifying their partitioning under non-standardised semi-environmental conditions into mobile environmental media, focusing on water and air, and comparing it to long chain PFC(A)s. Results are: Partitioning between water and particles in the aeration tank, primary and secondary clarifier of a wastewater treatment plant (WWTP) showed no distinct differences for short chain PFC(A)s compared to their long chain homologues (Paper 1). In a water-saturated sandy sediment column short chain PFC(A)s were not retarded, whereas long chain homologues were retarded by sorption to the sediment (Paper 2). Atmospheric particle-gas partitioning showed a lower fraction sorbed to particles for short chain PFC(A)s compared to long chain ones in samples from a WWTP (Paper 3). Air-water concentration ratios based on samples from the tanks of a WWTP were found to be higher for short chain PFC(A)s compared to long chain PFC(A)s (Paper 1). Additionally, in a newly developed experimental set-up the water to air transfer was used to derive that the pKa of C4-11-PFCAs must be <1.6 instead of up to 3.8 as reported in the literature (Paper 4). Overall, in the investigated systems short chain PFC(A)s showed a higher mobility due to a more pronounced partitioning into mobile environmental media compared to long chain PFC(A)s. In the second part of the thesis it was shown how PFO(A) - owing to its persistent, bioaccumulative and toxic (PBT-)properties – was in the context of this thesis successfully assessed as a substance of very high concern according to the criteria of the European REACH Regulation (EC No 1907/2006) by using data from non-standard tests (Paper 5). In conclusion, based on the knowledge of the high environmental mobility of short chain PFC(A)s and taking into account the argumentation of the PBT-concern of PFO(A), environmental exposure to short chain PFC(A)s is of concern and existing knowledge is already sufficient to initiate measures to prevent emissions of short chain PFC(A)s and their precursors into the environment.
Die Entfernung von Phosphor aus Abwasser bleibt ein Forschungsthema, das in Zukunft nur an Wichtigkeit gewinnen kann. Das wird durch die Umweltauswirkungen der Eutrophierung und den Verlust eines essentiellen Nährstoffes für die Nahrungsmittelproduktion dessen Knappheit immer offensichtlicher wird, immer deutlicher. Auf Kläranlagen werden heute hauptsächlich zwei Techniken verwendet um Phosphor zu entfernen, biologisch aktive Verfahren wie das Enhanced Biological Phosphorus Removal (EBPR) Verfahren und Fällungstechniken unter Verwendung von Metallsalzen. Bei beiden Methoden gibt es gegenwärtig Schwierigkeiten wie z.B. die Instabilität des EBPR Prozesses wegen des Mangels an Wissen über die Grundlagen des Stoffwechselprozesses. Bei der Verwendung von Fällungsmitteln kommt es zu vielen Nachteilen im Zusammenhang mit der Nachbehandlung des Schlammes, bei der Entsorgung kommt es zu dem Verlust der Schlammmassen und damit auch des Phosphors aus dem Nährstoffkreislauf. Das Ergebnis dieser Forschung ist, dass es möglich ist, die Phosphorspeicherkapazität von Belebtschlamm zu erhöhen wenn dieser spezifische Anforderungen erfüllt. Diese Anforderungen werden wie folgt zusammengefasst: Die Schlammmasse muss in der Lage sein, EBPR Prozesse zu entwickeln, auch muss der Schlamm aus einem Belebungsbecken-System kommen, weil die Schlammflocken unter den Umgebungsbedingungen des Reaktors stabilisiert worden sind. Schließlich muss der Belebtschlamm aus einem Verfahren kommen, bei dem man für die Phosphorentfernung keine Metallsalze verwendet. Die erhöhte Phosphorstoffspeicherkapazität der Belebtschlammmassen in Verbindung mit der Möglichkeit den Phosphor aus dem Belebtschlamm über Rücklösung in die wässrige Phase wieder gewinnen zu können, bietet großes Potential in der Zukunft einen in der Abwasserwirtschaft geschlossenen Phosphorkreislauf zu entwickeln und so den Verlust des wichtigen Nährstoffes nachhaltig zu verhindern.
Human activities have converted natural ecosystems worldwide, mostly for agricultural purposes. This change in land use has been recognized as one of the key drivers causing mass extinction of biodiversity. Yet, there are species which persist particularly in traditional, low-intensity agricultural areas. However, this farmland biodiversity is increasingly threatened by the consequences of land-use intensification and land abandonment. One effect of these two processes is the change in existing landscape structures. This dissertation aimed at quantifying the relationship between biodiversity and landscape structures because a better understanding of current biodiversity patterns and their drivers is needed to navigate biodiversity conservation for a sustainable development. Specifically, this dissertation anticipates the impacts of land-use change on biodiversity in Southern Transylvania, focusing on butterflies and plants as study groups. In a first step, a methodological baseline for subsequent biodiversity studies is developed by exploring an optimal survey strategy, allocating the available resources in a study design that enables high statistical power and covers a wide range of environmental conditions. This study shows that in the highly heterogeneous farmland mosaic of Southern Transylvania, survey effort can be moderately reduced while still showing similar patterns of species richness, species turnover and species composition (Chapter 2). In a second step, biodiversity patterns of plants and butterflies are empirically investigated in response to different landscape structures, particularly towards heterogeneity and woody vegetation cover. These studies provide evidence that all main land-use types in Southern Transylvania, namely arable land, grassland and forests, contribute to an overall landscape pool. Species richness of plants, but not of butterflies, differed significantly between arable land and grassland. Presence of woody vegetation in farmland had a positive effect on plant species richness. Heterogeneity has been found beneficial for butterfly species richness in arable land, but not in grasslands. Species composition of plants was determined by land-use, but butterfly species composition was widely overlapping in arable land and grassland (Chapters 3 & 4). Investigations on the potential spread of invasive plant species in the Transylvanian landscape exhibited that distance to roads and heterogeneity, especially in arable land, were key variables determining the invasibility of the landscape (Chapter 5). By studying movement patterns of butterflies in agricultural landscapes, land-use intensity could be revealed having an impact on butterfly movements. Furthermore, butterflies were found to prefer non-arable patches within farmland (Chapter 6). In a third step, this dissertation conceptually embeds socio-economic considerations into the local and international discourse on sustainable rural development: Reflections on a participatory projects on establishing butterfly monitoring in Romania conclude that involving citizens in biodiversity conservation is possible in Romania, but need tailored approaches which consider the unique social and cultural settings (Chapter 7). Current recommendations from scientific literature to increase the agricultural yield, for example in Eastern European landscapes, through ´sustainable intensification´ for global food security are scrutinized for their engagement with sustainability. This dissertation concludes that genuine sustainable solutions need to respect the various aspects of sustainability, including procedural and distributive justice. Furthermore, it is clarified that general recommendations for agricultural intensification, for instance in Romania, may lead to devastating impacts on biodiversity and ecosystem functions (Chapter 8). This dissertation provides evidence that the beneficial characteristics of the Translvanian farmland are linked to the fine spatial scale of the agricultural mosaic, the amount and distribution of semi-natural elements and the scattered woody vegetation throughout the landscape. Hence, the future of biodiversity depends on human interventions in the ancient cultural landscape. Navigating biodiversity conservation in Southern Transylvania thus needs genuine sustainable solutions, which integrate socially acceptable and ecological meaningful landscape management.
The concept of corporate entrepreneurship continues to occupy the minds of scholars and practitioners alike. This is not surprising as corporate entrepreneurship constitutes a major driver of organizational revitalization, learning, and growth within large and medium size organizations. However, despite extensive research on corporate entrepreneurship, there is still confusion about the interplay of its macro- and micro-level constituents. To unveil how the structures, practices, and behaviors, which constitute entrepreneurship in large, diversified firms, interact, I utilize a systemic reasoning and link the notion of corporate entrepreneurship to diverse theoretical positions in the strategic management field including intraorganizational ecology, institutional theory, and configuration theory - links that have been so far neglected in the literature on corporate entrepreneurship. I develop my arguments in three complementary articles. In the first article, I provide a review of the theoretical framework that to a large extent underpins my research: the Bower-Burgelman process model. In the second article, I take a qualitative case study approach to analyze how micro-level practices affect the intraorganizational and external environment in favor of an entrepreneurial initiative. In the third article, I identify four different design types on the basis of a qualitative meta-synthesis, which reflect coherent constellations of managerial interpretive-schemes, structures, and systems that cultivate entrepreneurial behavior. In sum, this dissertation contributes to a new understanding of corporate entrepreneurship as a system of entrepreneurially behaving actors who are constrained and simultaneously enabled by a set of social, cultural, political, and structural context factors.
This paper-based dissertation deals with the concepts of economic heterogeneity and environmental uncertainty from different perspectives, and at multiple levels of abstraction. At its core sits the observation that heterogeneity and uncertainty are deeply entangled, for there would be no uncertainty without heterogeneity of options to act regarding multiple future states of the world. At the same time, heterogeneity - in the form of diversification - has been suggested as a way to reduce uncertainty in portfolio theory (Markowitz 1952). The dissertation evolves around two research foci: (1) methodological implications of heterogeneity of scientific theories in the face of empirical data (Paper 1), and (2) two different forms of uncertainty are considered, environmental risk (Paper 2) and Knightian uncertainty (Paper 3). Paper 1 develops a new framework for model selection for the special case of fitting size distribution models to empirical data. It combines Bayesian and frequentist statistical approaches with the criterion of model microfoundation, which is to select, all other things considered being equal, the model that comes with a suitable micromodel, that explains, from the perspective of the individual constituent, the genesis of the overall size distribution. The approach is subsequently illustrated with size distribution data on commercial cattle farms in Namibia. We find that the double-Pareto lognormal distribution fits the data best. Our approach might have the potential to reconcile one of the oldest debates in current economics, i.e. the one about the best model to describe and explain the distribution of economic key variables such as income, wealth and city sizes in a country. The second paper revisits the Namibian commercial cattle farm data and uses it to put some theories from the agricultural economics literature regarding farm management under environmental risk to an empirical test. We focus on the relations between inter-annual variability in rainfall (environmental risk), risk preferences, farm size and stocking rate. We demonstrate that the Pareto distribution - which separates the distribution into two parts - is a statistically plausible description of the empirical farm size distribution when ´farm size´ is operationalized by herd size, but not by rangeland area. A statistical group comparison based on the two parts of the Pareto distribution shows that large farms are on average exposed to significantly lower environmental risk. Regarding risk preferences, we do not find any significant differences in mean risk attitude between the two branches. Our analysis confirms the central role of the stocking rate as farm management parameter, and shows that environmental risk and the farmer´s gender are key variables in explaining stocking rates in our data. Paper 3 develops a non-expected-utility approach to decision making under Knightian uncertainty which circumvents some of the conceptual problems of existing approaches. We understand Knightian uncertainty as income lotteries with known payoffs but unknown probabilities in each outcome. Based on seven axioms, we show that there uniquely (up to linear-affine transformations) exists an additive and extensive function from the set of Knightian lotteries to the real numbers that represents uncertainty preferences on the subset of lotteries with fixed positive sum of payoffs over all possible states of the world. We define the concept of uncertainty aversion such that it allows for interpersonal comparison of uncertainty attitudes. Furthermore, we propose Renyi´s (1961) generalized entropy as a one-parameter preference function, where the parameter measures the degree of uncertainty aversion. We illustrate it with a simple decision problem and compare it to other decision rules under uncertainty (maximin, maximax, Laplacian expected utility, minimum regret, Hurwicz).
Rethinking Gamification
(2014)
Gamification marks a major change to everyday life. It describes the permeation of economic, political, and social contexts by game-elements such as awards, rule structures, and interfaces that are inspired by video games. Sometimes the term is reduced to the implementation of points, badges, and leaderboards as incentives and motivations to be productive. Sometimes it is envisioned as a universal remedy to deeply transform society toward more humane and playful ends. Despite its use by corporations to manage brand communities and personnel, however, gamification is more than just a marketing buzzword. States are beginning to use it as a new tool for governing populations more effectively. It promises to fix what is wrong with reality by making every single one of us fitter, happier, and healthier. Indeed, it seems like all of society is up for being transformed into one massive game. The contributions in this book offer a candid assessment of the gamification hype. They trace back the historical roots of the phenomenon and explore novel design practices and methods. They critically discuss its social implications and even present artistic tactics for resistance. It is time to rethink gamification!
This thesis makes an important contribution to better understanding biodiversity and ecosystem function relationships across trophic levels in forests - aspects that are still underrepresented in BEF research. Ongoing biodiversity loss can be expected to change important trophic interaction pathways in these ecosystems, making increased efforts in exploring the mechanisms underlying, and the drivers determining, the impact of trophic complexity on the relationships between biodiversity and ecosystem functioning a crucial objective for holistic approaches to BEF research.