The aims of this thesis are to conduct a comprehensive investigation into the theoretical and methodological aspects of environmental footprints and into the disciplinary relationship with the... Show moreThe aims of this thesis are to conduct a comprehensive investigation into the theoretical and methodological aspects of environmental footprints and into the disciplinary relationship with the latest science in defining planetary boundaries for human activities. Main conclusions are as follows: (1) environmental footprints are measures of anthropogenic pressure or impact on the planet's environment irrespective of their precise units and dimensions; (2) environmental footprints are classified into the inventory-oriented footprints and impact-oriented footprints, which offer two competing paradigms for footprint indicators; (3) integrating the impact-oriented footprints provides policy makers with a unified approach to assessing overall environmental impacts and has a broader scope of applicability than life cycle assessment; (4) life cycle assessment cannot be interpreted as a versatile tool for accounting for all possible environmental footprints, although the footprint community has indeed learned and borrowed much from it; (5) latest science in planetary boundaries is found to complement environmental footprints in assessing environmental sustainability that is a critical prerequisite for the economic and social pillars of sustainable development; and (6) the sustainability gap between the converted footprint and boundary metrics plays a central role in understanding the national performance on individual and collective environmental issues. Show less
Carnivores are an important component of many ecological systems and they play a vital role in maintaining ecosystem health (Terborgh et al., 1999; Terborgh et al., 2002; Ray et al., 2005). Being... Show moreCarnivores are an important component of many ecological systems and they play a vital role in maintaining ecosystem health (Terborgh et al., 1999; Terborgh et al., 2002; Ray et al., 2005). Being at the top of the food chain, carnivores have important ecological impacts, such as the regulation of mesopredators and prey numbers present in an area (Terborgh et al., 1999). Important cascading trophic effects, caused by population changes of their prey or of sympatric mesopredators, may result when some of these large carnivores are extirpated from ecosystems. Unexpected effects of trophic cascades on various taxa and processes include changes to other vertebrates and herpetofaunal abundance or diversity. It could also have indirect effects and altered disease dynamics; carbon sequestration; modified stream morphology; and crop damage (Ray, 2005). Therefore, promoting tolerance and coexistence with large carnivores is a more crucial societal challenge now than ever before. The removal of top predators from ecosystems commonly results in dramatic changes in biodiversity and community structure, and as a result these areas can have severe consequences for the functioning of ecosystems (Berger et al., 2001; Terborgh et al., 1999). Show less
This thesis aims to evaluate the environmental sustainability of European imports of farmed aquatic food products from Asia, using life cycle assessment (LCA). Farming of Asian tiger prawn,... Show moreThis thesis aims to evaluate the environmental sustainability of European imports of farmed aquatic food products from Asia, using life cycle assessment (LCA). Farming of Asian tiger prawn, whiteleg shrimp, freshwater prawn, tilapia and pangasius catfish in Bangladesh, China, Thailand and Vietnam were chosen as representatives of the Asian aquaculture industry. Initial research revealed large discrepancies among LCA results driven by methodological choices and data sourcing. A protocol for quantifying dispersions around unit process data was therefore developed, characterising inherent uncertainty, spread (variability) and unrepresentativeness as the three major sources driving overall discrepancies. Results, propagated using Monte Carlo simulations, highlighted that the uncertainty related to LCA results could range with over an order of magnitude. For comparative purposes, however, only relative uncertainties are of relevance. Defining a hypothesis and using dependent sampling therefore allowed for several significant conclusions to be identified. Among these were significantly lower environmental impacts of Asian tiger shrimp farming in western Bangladesh, tilapia in Guangdong and pangasius in large-scale farms. Common environmental hot-spots included aqua-feeds, eutrophying effluents from farms, the use of benzalkonium chloride and other chlorine releasing compounds as disinfectants, and extensive use of paddle-wheels on shrimp farms. The research identified discrepancies Show less
The overall framework of the thesis is to develop an approach to compare the impacts between leaving biomass residues in fields and utilizing them for bioenergy. In this regard, residue-based... Show moreThe overall framework of the thesis is to develop an approach to compare the impacts between leaving biomass residues in fields and utilizing them for bioenergy. In this regard, residue-based bioenergy should be managed differently from product-based bioenergy. The objectives of this thesis are to identify the key issues when conducting a life cycle assessment (LCA) of residue-based bioenergy and to propose improvement in LCA procedures, specifically in the areas of life cycle inventory (LCI), life cycle impact assessment (LCIA), and methodological choices in the comparative LCA. It was discovered that the key issues associated with residue-based bioenergy relate to four primary characteristics with respect to its raw materials (biomass residues), i.e., excessive removal from plantation fields which can affect soil fertility; valuation (relative to biomass products); competing uses (bioenergy, feed, fiber, fertilizers); and treatment of biogenic carbon (assumptions of carbon neutrality vs. complete inventory). These unique features require specific LCA approaches which vary from those of conventional product-based bioenergy. These approaches include: [1] solutions to the existing dissimilar practices in the LCI of biogenic carbon; [2] an LCIA method of removing biomass residues from soil on biomass productivity; and [3] methodological choices in comparative LCA of biomass residues utilization. Show less
Our study emphasizes the importance of two toxicity-modifying factors (the composition of the surrounding exposure media and mixture effects) in the assessment of toxic effects of metals and... Show more Our study emphasizes the importance of two toxicity-modifying factors (the composition of the surrounding exposure media and mixture effects) in the assessment of toxic effects of metals and metal-based NPs on higher plants. Based on the affinity of metals for binding sites on the biotic ligand at the water-organism interface, the mechanistic models we developed provide better links with the toxicity of metal mixtures. We also recommend that finding a statistically significant deviation from additivity can be the starting point for further mechanistic research concerning toxicologically relevant interactions between substances, instead of the endpoint of research used so far. As an extension of the research discussed in the third chapter of this thesis, the commonly known model for the toxicity of mixtures was proven to be suitable for preliminarily assessing the effects of metal-based NPs on terrestrial organisms. The experimental design of nested combinations helps establish a more realistic exposure scenario for the environment and makes it possible to identify where and how chemical-chemical interactions occur with metal-based NPs. Consequently, our findings enrich the rapidly evolving field of toxicology regarding metals and metal-based NPs. Show less
Nanoparticles (NPs) exhibit special physicochemical properties compared to bulk particles. The difference in properties could, in principle, produce different effects on organisms. It is therefore... Show moreNanoparticles (NPs) exhibit special physicochemical properties compared to bulk particles. The difference in properties could, in principle, produce different effects on organisms. It is therefore important to determine the relationship between the physicochemical characteristics of NPs and their toxicity profile, by means of experimental testing. Experimental toxicity testing data can also be used to find the best dose metric for the responses induced by NPs, which was the purpose of the research presented in this thesis. Furthermore, this thesis aims to move forward from toxicity testing primarily in animal models to computational dose metric modeling. Show less
The aim of this PhD was to identify important factors that affect toxicity of copper nanoparticles (NPs), and to explore suited evaluation strategies to better understand the risk of metallic NPs... Show moreThe aim of this PhD was to identify important factors that affect toxicity of copper nanoparticles (NPs), and to explore suited evaluation strategies to better understand the risk of metallic NPs to organisms from different trophic levels. Based on this aim, the specific objectives of this PhD-thesis were: [1] To develop a framework for nanotoxicity testing to better understand the toxicity of NPs across species. [2] To apply the proposed testing framework to evaluate the toxicity of NPs, using species from different trophic levels. [3] To assess the risk of NPs by comparing the toxicity of NPs at different trophic levels. Three spherical copper NPs (CuNPs) with different diameters (25, 50 and 100 nm), one type of rod shaped CuNP (78 nm) and one type of micro copper particle (500 nm) were used in this thesis. Two types of mammalian cell lines and two types of piscine cell lines (Chapter 3), five cladoceran species (Chapter 4), three Lemnaceae species (Chapter 5) and three fish species (Chapter 6) were used to determine the toxicity of CuNPs. The species used covered different trophic levels and hence can provide systematic information for the risk assessment of CuNPs in the environment. Show less
In Dutch waters, two seal species occur namely common seals (Phoca vitulina vitulina) and grey seals (Halichoerus grypus). In the 1970s, the common seal population reached a historical low point... Show moreIn Dutch waters, two seal species occur namely common seals (Phoca vitulina vitulina) and grey seals (Halichoerus grypus). In the 1970s, the common seal population reached a historical low point after centuries of hunting, followed by exposure to pollution. Grey seals had already disappeared from Dutch waters in the preceding centuries, probably due to hunting. In this thesis, seals were studied over a period of four decades (1971-2013) in which the common seals have shown a recovery and the grey seals successfully recolonised Dutch waters. The research is conducted in the period 2006-2013 at the Seal Rehabilitation and Research Centre (Pieterburen) in collaboration with several universities. A multidisciplinary approach has been applied to learn more about the biology and pathology of seals and to obtain a comprehensive view on their status in Dutch waters. The patterns and trends in stranding were studied for both seal species, followed by a study of their current genetic status. Based on the analysis of stranding data, parasitic pneumonia (common seals only) and orphanage (both species) were found to be the main causes of stranding. Therefore, the occurrence of parasitic infections and the breeding biology of seals were studied in the following chapters. Show less
In the natural aquatic environment, different abiotic and biotic factors may affect the fate of pesticides, and the performance of organisms. The overall aim of this thesis was to study the effects... Show moreIn the natural aquatic environment, different abiotic and biotic factors may affect the fate of pesticides, and the performance of organisms. The overall aim of this thesis was to study the effects of pesticides on aquatic macrofauna in the field. Different approaches were used in research, including field sampling of aquatic macrofauna, in situ exposure experiments, and laboratory toxicity tests. Fieldwork was based in the flower bulb growing area of the Netherlands were pesticide concentrations in surface waters often exceed water quality standards. Show less
Insights into the spatial distribution of genetic diversity is key for understanding the evolutionary history and for effective species conservation. For the lion, all African populations are... Show moreInsights into the spatial distribution of genetic diversity is key for understanding the evolutionary history and for effective species conservation. For the lion, all African populations are considered to belong to one subspecies, while the Asiatic subspecies is confined to a single population in India. However, it is suggested that the genetic diversity is greater than the taxonomy implies. Notably the West and Central African lion represents a unique clade, which is relevant because the populations in this region are generally small and isolated. Phylogenetic analyses of mtDNA data, microsatellites and autosomal SNPs from lion populations throughout their complete geographic range show congruent patterns in which the Asiatic subspecies has a nested position within the West/Central African lion. Recognizing a northern subspecies, including the Asiatic lion, and a southern subspecies, is more in line with the evolutionary history of the lion. A revision of the taxonomy is therefore warranted. Show less
