Institut für sozial-ökologische Forschung (ISOE)
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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.
The design of rainwater harvesting based gardens requires considering current climate but also climate change during the lifespan of the facility. The goal of this study is to present an approach for designing garden variants that can be safely supplied with harvested rainwater, taking into account climate change and adaptation measures. In addition, the study presents a methodology to quantify the effects of climate change on rainwater harvesting based gardening. Results of the study may not be accurate due to the assumptions made for climate projections and may need to be further refined. We used a tank flow model and an irrigation water model. Then we established three simple climate scenarios and analyzed the impact of climate change on harvested rain and horticulture production for a semi-arid region in northern Namibia. In the two climate scenarios with decreased precipitation and medium/high temperature increase; adaptation measures are required to avoid substantial decreases in horticulture production. The study found that the most promising adaptation measures to sustain yields and revenues are a more water efficient garden variant and an enlargement of the roof size. The proposed measures can partly or completely compensate the negative impacts of climate change.
Namibia is known to be the most arid country south of the Sahara. Average annual rainfall is not only relatively low in most parts of the country, it is also highly variable. Only 8 per cent of the country receives enough rain during a normal rainy season to practice rainfed cultivation. At the same time between 60 per cent and 70 per cent of the population depend on subsistence agro-pastoralism in non-freehold or communal areas. Against the background of rising unemployment, the livelihoods of the majority of these people are likely to depend on natural resources in the foreseeable future.
Natural resources generally are under considerable strain. As the rural population increases, so is the demand for natural resources, land and water specifically. Dependency on subsistence farming which is the result of large scale rural poverty exacerbates the problem. Large parts of the country are stocked injudiciously, resulting in overgrazing and water is frequently overabstracted, leading to declining water tables (MET 2005: 2).
Unequal access to both land and water has prompted government to introduce reforms in these sectors. These reforms were guided by the desire to manage resources more sustainably while providing more equal access to them. In terms of NDP 2, sustainability means to use natural resources in such a way so as not to ‘compromise the ability of future generations to make use of these resources’ (NDP 2: 595).
Immediately after Independence government started reform processes in the land and water sectors. However, these reforms have happened at different paces and largely independent of each other. Increasingly policy makers and development practitioners realised that land and water management needed to be integrated, as decisions about land management and land use options had a direct impact on water resources. Conversely the availability of water sets the parameters for what is possible in terms of agricultural production and other land uses. The north-central regions face a particular challenge in this regard as the region carries more livestock than it can sustain in the long run. At the same time, close to half the households do not own any livestock. Access to livestock by these households would improve their abilities to cultivate their land more efficiently in order to feed themselves and thus reduce poverty levels.
But livestock are a major consumer of water. In 2000 livestock was consuming more water than the domestic sector. The figures were 77Mm3/a and 67Mm3/a respectively (Urban et al. 2003 Annex 7: 2). This situation has prompted a Project Progress Report on the Namibia Water Resources Management Review in 2003 to conclude that Given the extreme water scarcity in most parts of the country, land and water issues are closely linked. It therefore seems indispensable to mutually adjust land – and water sector reform processes (Ibid: 20).
This paper will briefly look at four institutions that are central to land and water management with a view to assess the extent to which they interact. These are Communal Land Boards, Water Point Committees, Traditional Authorities and Regional Councils. A discussion of relevant policy documents and legislative instruments will investigate whether the existing policy framework
provides for an integrated approach or not. Before doing this, it appears sensible to briefly situate these four institutions in the wider maze of institutions operating at regional and
sub-regional level. All these institutions – important as they are in the quest to improve participation at the regional and sub-regional level – are competing for time and input fros mallscale farmers.
An increasing number of voices highlight the need for science itself to transform and to engage in the co-production of knowledge and action, in order to enable the fundamental transformations needed to advance towards sustainable futures. But how can global sustainability-oriented research networks engage in co-production of knowledge and action? The present article introduces a strategic tool called the ‘network compass’ which highlights four generic, interrelated fields of action through which networks can strive to foster co-production. It is based on the networks’ particular functions and how these can be engaged for co-production processes. This tool aims to foster self-reflection and learning within and between networks in the process of (re)developing strategies and activity plans and effectively contributing to sustainability transformations.
The UN 2030 Agenda for Sustainable Development stresses the fundamental role science should play in implementing the 17 Sustainable Development Goals endorsed by the global community. But how can and should researchers respond to this societal demand on science? We argue that answering this question requires systematic engagement with the fundamental normative dimensions of the 2030 Agenda and those of the scientific community—and with the implications these dimensions have for research and practice. We suggest that the production of knowledge relevant to sustainable development entails analytic engagement with norms and values through four tasks. First, to unravel and critically reflect on the ethical values involved in sustainability, values should increasingly become an empirical and theoretical object of sustainability research. Second, to ensure that research on social–ecological systems is related to sustainability values, researchers should reflect on and spell out what sustainability values guide their research, taking into account possible interdependencies, synergies, and trade-offs. Third, to find common ground on what sustainability means for specific situations, scientists should engage in deliberative learning processes with societal actors, with a view to jointly reflecting on existing development visions and creating new, contextualized ones. Fourth, this implies that researchers and scientific disciplines must clarify their own ethical and epistemic values, as this defines accountability and shapes identification of problems, research questions, and results. We believe that ignoring these tasks, whether one is in favor or critical of the 2030 Agenda, will undermine the credibility and relevance of scientific contributions for sustainable development.
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.