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排序方式: 共有218条查询结果,搜索用时 15 毫秒
211.
212.
Abstract

Media and academic debates about the environment have increasingly made reference to the so-called ‘eco-preneur’ (‘green entrepreneur’ or ‘environmental entrepreneur’). These discussions encourage us to see the potential of such figures to act as drivers of environmental innovation. Their combination of entrepreneurial zeal and green motivations is seen as providing them with the ability to transcend the usual tensions between business and the environment. In academic circles a new literature is beginning to emerge around this perspective, ‘eco-preneurship’. In this paper we investigate the usefulness of eco-preneurship for understanding environmental innovation. In particular we ask where this literature, supported by popular images in the media, fixes our gaze when we think about environmental innovation in society. And, crucially, what might we be missing by concentrating our attention on these eco-preneurs? The paper concludes by suggesting that environmental innovation is better understood as an inherently messy and complex institutional process, which cannot be reduced to the psychology of entrepreneurial personalities.  相似文献   
213.
Pollinator declines have prompted efforts to assess how land-use change affects insect pollinators and pollination services in agricultural landscapes. Yet many tools to measure insect pollination services require substantial landscape-scale data and technical expertise. In expert workshops, 3 straightforward methods (desk-based method, field survey, and empirical manipulation with exclusion experiments) for rapid insect pollination assessment at site scale were developed to provide an adaptable framework that is accessible to nonspecialist with limited resources. These methods were designed for TESSA (Toolkit for Ecosystem Service Site-Based Assessment) and allow comparative assessment of pollination services at a site of conservation interest and in its most plausible alternative state (e.g., converted to agricultural land). We applied the methods at a nature reserve in the United Kingdom to estimate the value of insect pollination services provided by the reserve. The economic value of pollination services provided by the reserve ranged from US$6163 to US$11,546/year. The conversion of the reserve to arable land would provide no insect pollination services and a net annual benefit from insect-pollinated crop production of approximately $1542/year (US$24∙ha–1∙year–1). The methods had wide applicability and were readily adapted to different insect-pollinated crops: rape (Brassica napus) and beans (Vicia faba) crops. All methods were rapidly employed under a low budget. The relatively less robust methods that required fewer resources yielded higher estimates of annual insect pollination benefit.  相似文献   
214.
It has been suggested that differences in body size between consumer and resource species may have important implications for interaction strengths, population dynamics, and eventually food web structure, function, and evolution. Still, the general distribution of consumer-'resource body-size ratios in real ecosystems, and whether they vary systematically among habitats or broad taxonomic groups, is poorly understood. Using a unique global database on consumer and resource body sizes, we show that the mean body-size ratios of aquatic herbivorous and detritivorous consumers are several orders of magnitude larger than those of carnivorous predators. Carnivorous predator-prey body-size ratios vary across different habitats and predator and prey types (invertebrates, ectotherm, and endotherm vertebrates). Predator-prey body-size ratios are on average significantly higher (1) in freshwater habitats than in marine or terrestrial habitats, (2) for vertebrate than for invertebrate predators, and (3) for invertebrate than for ectotherm vertebrate prey. If recent studies that relate body-size ratios to interaction strengths are general, our results suggest that mean consumer-resource interaction strengths may vary systematically across different habitat categories and consumer types.  相似文献   
215.
Riefler RG  Medina VF 《Chemosphere》2006,63(6):1054-1059
Nitroglycerine (NG) and 2,4-dinitrotoluene (2,4-DNT) are propellants often found in soil and groundwater at military firing ranges. Because of the need for training with live ammunition, control or cleanup of these contaminants may be necessary for the continued use of these firing ranges. One inexpensive approach for managing sites exposed to these contaminants is the use phytoremedation, particularly using common or native grasses. In this study, the uptake of NG and 2,4-DNT from water by three common grasses, yellow nutsedge (Cyperus escalantus), yellow foxtail (Setaria glauca), and common rush (Juncus effusus), was investigated using hydroponic reactors. Rapid removal from solution by all grasses was observed, with yellow nutsedge removal rates being the highest. NG or 2,4-DNT accumulated in the tissues in all of the plants, except yellow foxtail did not accumulate NG. Higher concentrations were observed in killed roots, demonstrating the presence of plant-based enzymes actively transforming the contaminants. Yellow nutsedge was also grown in 2,4-DNT spiked soil. Significant uptake into the plants roots and leaves was observed and concentrations in the soil decreased rapidly, although 2,4-DNT concentration also decreased in the unplanted controls. In summary, the three grasses tested appear to be good candidates for phytoremediation of propellant contamination.  相似文献   
216.
Environmental investigations have been conducted at 23 military firing ranges in the United States and Canada. The specific training facilities most frequently evaluated were hand grenade, antitank rocket, and artillery ranges. Energetic compounds (explosives and propellants) were determined and linked to the type of munition used and the major mechanisms of deposition.  相似文献   
217.
In this paper we look behind the notion of sustainable transport and highlight the tensions and contradictions between the different ways of achieving this. The paper examines transportation plans for a major UK city and describes how these develop the idea and practice of sustainable transport and demand management along three quite distinct trajectories. By focusing on both the technological and the institutional dimensions of three different routes to sustainable transport, the analysis explicates the different ways in which the urban transport problem is framed, the different socio-technical logics of demand management embodied in the plans and the differing ways in which institutional relationships are (re)constituted. A key finding is that technological and institutional innovations are inversely related so that radical technological innovation often serves to reinforce existing social relations of power and exclusion. The conclusion drawn is that the choice is not just between a sustainable and an unsustainable transport future, but also between different forms of sustainability.  相似文献   
218.
Environmental Science and Pollution Research - A composite material prepared by polymerization of β-cyclodextrin (β-CD) on the surface of natural hydroxyapatite using citric acid as cross...  相似文献   
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