333.7 Natürliche Ressourcen, Energie und Umwelt
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Highlights
• PUR, PVC and PLA microplastics affect life-history parameters of Daphnia magna.
• Natural kaolin particles are less toxic than microplastics.
• Microplastic toxicity is material-specific, e.g. PVC is most toxic on reproduction.
• In case of PVC, plastic chemicals are the main driver of microplastic toxicity.
• PLA bioplastics are similarly toxic as conventional plastics.
Abstract
Given the ubiquitous presence of microplastics in aquatic environments, an evaluation of their toxicity is essential. Microplastics are a heterogeneous set of materials that differ not only in particle properties, like size and shape, but also in chemical composition, including polymers, additives and side products. Thus far, it remains unknown whether the plastic chemicals or the particle itself are the driving factor for microplastic toxicity. To address this question, we exposed Daphnia magna for 21 days to irregular polyvinyl chloride (PVC), polyurethane (PUR) and polylactic acid (PLA) microplastics as well as to natural kaolin particles in high concentrations (10, 50, 100, 500 mg/L, ≤ 59 μm) and different exposure scenarios, including microplastics and microplastics without extractable chemicals as well as the extracted and migrating chemicals alone. All three microplastic types negatively affected the life-history of D. magna. However, this toxicity depended on the endpoint and the material. While PVC had the largest effect on reproduction, PLA reduced survival most effectively. The latter indicates that bio-based and biodegradable plastics can be as toxic as their conventional counterparts. The natural particle kaolin was less toxic than microplastics when comparing numerical concentrations. Importantly, the contribution of plastic chemicals to the toxicity was also plastic type-specific. While we can attribute effects of PVC to the chemicals used in the material, effects of PUR and PLA plastics were induced by the mere particle. Our study demonstrates that plastic chemicals can drive microplastic toxicity. This highlights the importance of considering the individual chemical composition of plastics when assessing their environmental risks. Our results suggest that less studied polymer types, like PVC and PUR, as well as bioplastics are of particular toxicological relevance and should get a higher priority in ecotoxicological studies.
Establishing and maintaining protected areas (PAs) is a key action in delivering post-2020 biodiversity targets. PAs often need to meet multiple objectives, ranging from biodiversity protection to ecosystem service provision and climate change mitigation, but available land and conservation funding is limited. Therefore, optimizing resources by selecting the most beneficial PAs is vital. Here, we advocate for a flexible and transparent approach to selecting PAs based on multiple objectives, and illustrate this with a decision support tool on a global scale. The tool allows weighting and prioritization of different conservation objectives according to user-specified preferences as well as real-time comparison of the outcome. Applying the tool across 1,346 terrestrial PAs, we demonstrate that decision makers frequently face trade-offs among conflicting objectives, e.g., between species protection and ecosystem integrity. Nevertheless, we show that transparent decision support tools can reveal synergies and trade-offs associated with PA selection, thereby helping to illuminate and resolve land-use conflicts embedded in divergent societal and political demands and values.
Plastics contain a complex mixture of chemicals including polymers, additives, starting substances and side-products of processing. These plastic chemicals are prone to leach into the packaged goods, in the case of food contact materials (FCMs), or into the natural environment, in the case of plastic debris. Thus, plastics represent an exposure source of chemicals for humans and wildlife alike. While it is widely known that individual plastic chemicals, such as bisphenol A and phthalates, are hazardous, little is known on the overall chemical composition and toxicity of plastics. When fragmented into smaller particles, referred to as microplastics (< 5 mm), the plastic itself can be ingested by many species. It is well established that microplastic ingestion can have negative consequences for a wide range of organisms including invertebrates, but the contribution of plastic chemicals to the toxicity of microplastics is unclear.
Given the above, the present thesis aimed at a comprehensive toxicological, ecotoxicological and chemical characterization of everyday plastics. For a comparative evaluation, 77 plastic products were selected covering 16 material types (e.g., polyethylene) made from petroleum or renewable feedstocks. These products included biodegradable products, FCMs and non-FCMs, as well as raw materials and final products, respectively. In the first two studies, the chemical mixtures contained in the 77 products were extracted with methanol and extracts were analyzed in a set of four in vitro bioassays and by non-target high-resolution gas or liquid chromatography mass spectrometry. Since an exposure only occurs if chemicals actually leach under realistic conditions, in a third study migration experiments with water were conducted for 24 out of the 77 products. The aqueous migrates were assessed in the same way as the methanolic extracts. In addition, the freshwater invertebrate Daphnia magna was exposed chronically to microplastics made of polyvinylchloride (PVC), polyurethane (PUR) and polylactic acid (PLA) to investigate the contribution of chemicals in microplastic toxicity, in a fourth study.
The experimental findings demonstrate that a wide variety of chemicals is present in plastics. A single plastic product can contain up to several thousand chemical features, most of which unique to that product and at the same time unknown. The results also indicate that the majority of these chemical mixtures are toxic in vitro. Accordingly, 65% of the plastic extracts induced baseline toxicity and 42% an oxidative stress response, while 25% had an antiandrogenic and 6% an estrogenic activity. This implies that chemicals causing unspecific toxicity are more prevalent in plastics than such with endocrine effects. These chemicals can also leach from plastics under realistic conditions. Between 17 and 8936 chemical features were detected in a single migrate sample and all 24 tested migrates induced in vitro toxicity. This means that humans and wildlife can actually be exposed to toxic plastic chemicals under realistic conditions. Generally, each product has its individual toxicological and chemical fingerprint. Thus, neither material type, feedstock, biodegradability nor the food contact suitability of a product can serve as a predictor for the toxicity, the chemical composition or complexity of a product. Likewise, this means that bio-based and biodegradable materials are not superior to their petroleum-based counterparts from a toxicological perspective despite being promoted as sustainable alternatives to conventional plastics.
Moreover, the present thesis demonstrates that plastic chemicals can be the main driver for microplastic toxicity. Irregular microplastics made of PVC, PUR and PLA adversely affected life-history traits of D. magna in a polymer type- and endpoint-dependent manner at concentrations between 100 and 500 mg L-1 and with a higher efficiency than natural kaolin particles. While the toxicity of PVC was triggered by the chemicals used in the material, the effects of PUR and PLA were induced by the physical properties of the particle.
In addition, in the fifth study, results and observations made during this thesis were integrated inter- and transdisciplinarily with the perspectives of a social scientist and a product manufacturer. This elucidated that knowledge on plastic ingredients is often concealed, is lacking or not applicable in practice. These intransparencies hinder the safety evaluation of plastic products as well as the choice and sale of the least toxic packaging material.
Overall, the present thesis highlights that the chemical safety of plastics and their bio-based and biodegradable alternatives is currently not ensured. Thus, chemicals require more consideration in the toxicity and risk assessment of plastics and microplastics. Product-specific and complex chemical compositions, including unknown compounds, pose a challenge here. Two essential steps towards non-toxic products are to increase transparency along the product life cycle and to reduce the chemical complexity of plastics by communication and regulation. The results of the present thesis indicate that products exist which do not contain toxic chemicals. These can serve to direct the design of safer plastics. Since toxicity and chemical complexity seem to increase with processing, the integration of toxicity testing during the production steps would further support the safe and sustainable production and use of plastic products.
The green building evolution
(2019)
The Green Building Evolution illuminates global examples and makes use of case studies mainly from South Africa. This book is in five parts: Part I is a single introductory chapter centred on the evolution of the green building movement; Part II addresses the green building terrain; Part III presents selected case studies; Part IV focuses on chapters that address pushing the boundaries in the green building space; while Part V presents emerging trends and policy perspectives. Further details are contained in the main body of the book. It is our sincere hope that readers will experience the book as an informative and ground-breaking adventure. Written by 14 authors from different academic disciplines and areas of specialisation, the book comes as the sixth in a series that addresses global and national concerns on climate change, sustainable development and the green economy transition agenda. The book series is conceptualised and coordinated by the Exxaro Chair in Business and Climate Change, led by Prof. Godwell Nhamo and hosted by the Institute for Corporate Citizenship (ICC) at the University of South Africa (UNISA). The books are published by the Human Sciences Research Council (HSRC) through the Africa Institute of South Africa.
The anthropocene – the epoch of humankind – is currently a topic of great interest. What consequences does the idea of humanity as a geological force have for the undertaken path of sustainable development? What new questions are arising for sustainability science? Diagnosing contemporary society from an anthropocene perspective could change the relationship between natural and social sciences, as well as between society and science: science will be needed even more as a critical authority and must be organized to an even greater extent in a transdisciplinary manner. New forms of social participation in the process of producing scientifically legitimated knowledge are indispensable.∗
More than ten years ago the Dutch chemist and Nobel laureate Paul Crutzen coined the term “Anthropocene” to describe the period during which humans have begun to significantly influence biological, geological and atmospheric processes, thus becoming a relevant geological force on planet Earth (Crutzen and Stoermer 2000, Crutzen 2002). In the earth sciences the anthropocene represents nothing less than a transition to a new epoch and is therefore being discussed intensively. Until 2016 data have been collected by geologists from the International Commission on Stratigraphy (ICS) to provide evidence that might help answer the question whether a turning point has been reached in the history of the Earth (Zalasiewicz et al. 2011). A decision will be made as to whether and when a new epoch in Earth history has begun.
The significance and consequences outside the geoscientific discourse of identifying an “epoch of humans” (Zalasiewicz 2013) has, so far, only been understood to a small extent. Yet this change of perspective is one of the most important in the last 100 hundred years, for it means society and nature have become so closely intertwined that they can no longer be studied independently of each other. Natural spheres and societal spheres have merged into one large system (Guillaume 2015, Becker und Jahn 2006). A well-founded acceptance of the concept of the anthropocene, however, has been lacking, especially where transitions to a sustainable development are being researched. It remains unclear whether the concept of the Anthropocene will lead to a new fundamental understanding of the relationships between nature and society and, if so, what opportunities this new understanding might open for shaping these relationships in a more sustainable manner. And lastly, and equally importantly, it is still unclear whether science’s role and responsibilities will change in the course of developing visions of the future. With this article we hope to stimulate further discussions of these issues.
Competition over land is at the core of many sustainable development challenges in Myanmar: villagers, companies, governments, ethnic minority groups, civil society organisations and non-governmental organisations from local to the international level claim access to and decision-making power over the use of land. Therefore, this article investigates the actor interactions influencing land-use changes and their impacts on the supply of ecosystem services and human well-being. We utilise a transdisciplinary mixed-methods approach and the analytical lens of the social-ecological systems framework. Results reveal that the links between land-use changes, ecosystem services and human well-being are multifaceted; For example ecosystem services can decline, while human well-being increases. We explain this finding through three different pathways to impact (changes in the resource systems, the governance systems or the broader social, economic and political context). We conclude with implications of these results for future sustainable land governance.
Evidence is increasingly pointing towards a significant global decline in biodiversity. The drivers of this decline are numerous, including habitat change and overexploitation, rapid deforestation, pollution, exotic species and disease, and finally climate change as an emerging driver of biodiversity change (Nakamura, et al., 2013; Hancocks, 2001; Pereira, Navarro & Martins, 2012). Raising public awareness of the need to conserve biological diversity is essential to safeguard the richness of life forms all over the world (Lindemann-Matthies, 2002). In this regard, institutions such as science museums, zoos and aquariums have the potential to play an important role (Rennie & Stocklmayer, 2003). Especially, zoos can provide a productive learning environment (Miles & Tout, 1992), facilitating the promotion of public conservation awareness and the adoption of pro-environmental behaviours that would reduce negative human impacts on biodiversity (Barongi, et al., 2015).
Based on these concepts, my study contributes to the developing field of visitor studies. Taking as reference non-zoo visitors and zoo visitors, I have focused on reviewing some aspects of conservation education, such as people's awareness of conservation, people's interest in animals and people's feelings towards animals and attitudes towards zoos. The study identified differences between non-regular and regular zoo visitors in interests in animals, as well as visitor attitudes towards conservation issues and zoos. Therefore, the present study indicated that positive emotional reactions and, in particular, a perceived sense of connection to the animal were linked and depended on the frequency of zoo visits. It was as well remarkable, that conservation awareness was influenced by the interest in animals, the interest in visiting zoos, the attitudes towards these institutions, and the age and the country of origin. All these variables had a greater effect in the conservation consciousness of the participants. Additionally interestingly, the main reason for visiting zoos in every country was to learn something about animals. This highlights the educational role of zoos and broadly supports the idea that people want to visit zoos to learn something about animals, in turn facilitating pro-conservation learning and changes in attitude. They are uniquely positioned to interact with visitors, communities, and society and to contribute by providing an informative and entertaining environment. Visiting zoos could led to contribute to promoting animal connectedness and interest in species.
Science is under pressure. In times when it is a matter of nothing less that a transformation toward sustainable development, society and politics are demanding not just reliable knowledge but above all useful knowledge. In order to be able to produce such knowledge science must change its structures and ways of working. A renewed understanding of critique can provide guidance to the process of change that must be actively shaped by science itself.* The “Great Transformation” in the direction of sustainable development is a global challenge for society (WBGU2011). All involved have stressed that this transformation, if it succeeds, will lead to profound changes in all parts of society (see PIK 2007). This applies to science as well, which after all is a part of society (WBGU2011, pp. 341 f.). For in view of an unprecedented social-ecological crisis science is coming increasingly under pressure to provide knowledge that is not only methodically reliable but also useful for dealing with the challenges ahead. It is obvious this pressure can strike at the very core of the scientific project: Any orientation toward nonscientific criteria with respect to what is to count as relevant knowledge threatens to undermine the reflexive and cooperative search for “true knowledge.”
In this situation we believe it to be crucial that science does not allow itself to become a plaything of calls for change, but rather that it itself shapes its own response to the new historical challenges. In the following, we argue that a renewed understanding of critique should be the starting point for such an endeavor.1 We will illustrate what a renewed understanding of critique might look like by posing nine theses.2 We see these theses as a contribution to the ongoing discourse on sustainability science or research for sustainable development.
Responsibility for increasing mitigation ambition in light of the right to sustainable development
(2020)
The international community is currently in the midst of a facilitative dialogue about how to increase mitigation ambition under the terms of Paris Agreement. This dialogue concerns centrally considerations of equity, which includes matters of both justice and responsibility. I defend the importance of the right to sustainable development in this regard. I argue that if the right of states to pursue poverty eradicating human development is to be respected, then there is plausible interpretation of responsibility for mitigation in which a state’s ability to pay is the central consideration, where that ability is measured by its human development level. That conception of responsibility should be applied to considerations of how increase mitigation ambition.
Preface
(2019)
What's in a prefix? How to read a prefix as short as 're-'? Does 're-' really signify? Can it point into a specific direction? Can it reverse? Can it become the shibboleth of a 'postcritical' reboot? At first glance transparent and directional, 're-' complicates the linear and teleological models commonly accepted as structuring the relations between past, present, and future, opening onto errant temporalities.