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91.
Martin Christian Heinz Mathias ngel Lorenz M. 《Journal of environmental management》2009,90(11):3498-3511
With the intention of bridging the ‘digital divide’ many programmes have been launched to provide computers for educational institutions, ranging from refurbishing second hand computers to delivering low cost new computers. The fast and economical provision of large quantities of equipment is one of the many challenges faced by such programmes. If an increase is to be achieved in the sustainability of computer supplies for schools, not only must equipment be provided, but also suitable training and maintenance delivered. Furthermore, appropriate recycling has to be ensured, so that end-of-life equipment can be dealt with properly. This study has evaluated the suitability of three computer supply scenarios to schools in Colombia: (i) ‘Colombian refurbishment’, -refurbishment of computers donated in Colombia, (ii) ‘Overseas refurbishment’, -import of computers which were donated and refurbished abroad, and (iii) ‘XO Laptop’, -purchase of low cost computers manufactured in Korea. The methods applied were: Material Flow Assessment, -to assess the quantities-, Life Cycle Assessment, -to assess the environmental impacts, and the application of the Multiple Attribute Utility Theory, -to analyse, evaluate and compare different scenarios. The most sustainable solution proved to be the local refurbishment of second hand computers of Colombian origin to an appropriate technical standard. The environmental impacts of such practices need to be evaluated carefully, as second hand appliances have to be maintained, require spare parts and sometimes use more energy than newer equipment. Providing schools with second hand computers from overseas and through programmes such as ‘One Laptop Per Child’ has the disadvantage that the potential for social improvements – such as creation of jobs and local industry involvement – is very low. 相似文献
92.
《Journal of environmental science and health. Part. B》2012,47(12):948-953
AbstractOmethoate is an organophosphorus pesticide that poses a major health hazard, especially DNA damage. The purpose of this study was to investigate the factors affecting telomere length in workers exposed to omethoate by analyzing the interaction between cell cycle gene polymorphism and environmental factors. The exposure group consisted of 118 workers exposed to omethoate for 8–10?years, the control group comprised 115 healthy people without occupational toxicant exposure history. The telomere length of genomic DNA from peripheral blood leucocyte was determined with real-time PCR. Polymerase chain reaction and restriction fragment length polymorphism was used to detect the polymorphisms in p53, p21 and MDM2 gene. The telomere length in the (CA?+?AA) genotypes for p21 rs1801270 polymorphism was longer than that in the CC genotype in control group (P?=?0.015). The generalized linear model analysis indicated the interaction of the p21 rs1801270 polymorphic (CA?+?AA) genotypes and smoking has a significant effect on telomere length (β = ?0.258, P?=?0.085). The prolongation of telomere length in omethoate-exposed workers was associated with genotypes (CA?+?AA) of p21 rs1801270, and interactions of (CA?+?AA) genotypes and smoking factor. 相似文献
93.
The reproductive cycle of bivalves is regulated by several natural environmental factors but exposure to chemical pollutants can also interfere and may result in advanced or delayed spawning season. To our knowledge, the gametogenic cycle of the suspension-feeder bivalve Donax trunculus has not yet been used as biomonitoring tool in ecotoxicological surveys. The aim of this study was to examine over a year physiological reproductive endpoints (sex-ratio, gametogenic and energy reserve cycles) and biological indices (condition index, allometry) in D. trunculus originating from two sites differing by their level of contamination. Specimens were collected bimonthly from November 2008 to October 2009 from a polluted site (Radès Méliane) and a comparatively reference site (Sidi Jehmi) in the Gulf of Tunis (Tunisia). Five stages were depicted by histological examination of gonads: undifferentiated, developing, mature, spawn and spent. Differences in the gametogenic cycle according to the site of origin of bivalves were observed. The spawning period began in March and was maximum in May in bivalves from both sites, but the percentage of spawning animals was higher in the polluted site vs the reference site. The spawning period was shorter in animals from the polluted site comparatively to the reference site. Energy reserves (glycogen, lipids) were higher in March and May comparatively to the other studied periods in bivalves from both sites. Lower energy reserves levels were usually observed in animals from the polluted site compared to the reference site. Seasonal variations of the condition index were associated to the reproductive and nutritive status of bivalves. Differences in allometry were depicted between bivalves from both studied sites. If we try to link allometry, energy reserves and reproduction, it can be hypothesized that for bivalves from the reference site, energy reserves are allocated to gametogenesis and length growth. For bivalves from the polluted site, energy reserves could be devoted to tolerance to chemical stress and to reproductive processes. Therefore, D. trunculus appears as a suitable sentinel species for the assessment of the ecotoxicological risk of contaminants such as endocrine disruptors. 相似文献
94.
In reaction to a paper inEnvironmental Management in which the sense and sensibility of environmental assessments of packaging were questioned, it is argued that these types
of assessments may be very useful, provided the relevant types of questions are posed. These boundary conditions are discussed,
along with an overview of more recent methodological developments with respect to environmental assessment of products. 相似文献
95.
E. Worrell A. P. C. Faaij G. J. M. Phylipsen K. Blok 《Resources, Conservation and Recycling》1995,13(3-4)
Material efficiency improvement saves energy and reduces the consumption of primary resources and reduces the volume of waste. In this article an approach for analysing the potential for material efficiency improvement is proposed and discussed. In this approach the product functions performed by the materials and various improvement measures are taken into account. The potential for material saving and associated energy saving is assessed and evaluated economically. In this paper the approach is tested in an analysis of the potential for material efficiency improvement with respect to plastic packaging in the Netherlands. The technical reduction potential is found to be 34 ± 7% (157 ± 30 ktonne virgin plastics). Realization of this potential would improve the energy efficiency of the lifecycle of plastic packaging by 31% (10 PJ in 1988). From our study we conclude that our approach can indeed be used to investigate the potential for material efficiency improvement. However, a reliable technical and particularly an economical assessment of reduction measures cannot be made until more detailed data become available. 相似文献
96.
Calvin P. C. Poon Frank J. DeLuise 《Journal of the American Water Resources Association》1967,3(4):26-35
Manganese entering impounded water will undergo a cyclic transformation. Oxidation precipitates manganese from top waters. At the bottom of the lake, biological activity will render manganese soluble by both intracellular as well as extracellular activity. The study was made to demonstrate that biological reduction and transformation, organometallic complexation, together with the presence of carbon dioxide and the lowering of pH all have some effect on the solubility of manganese. Dissolved manganese may be brought back to top waters during the lake overturn and therefore deteriorates the water quality. 相似文献
97.
城市生活垃圾的生命周期管理 总被引:3,自引:0,他引:3
根据国际标准化组织1997 年颁布的ISO14000 环境管理体系“生命周期评价—原则与框架”,本文对可持续城市生活垃圾生命周期管理进行研究,指出城市生活垃圾应在环境可持续性、经济可负担性及社会可接受性的原则基础上,通过垃圾的减量化、无害化、资源化和社会化管理,实现城市可持续发展的管理目标 相似文献
98.
Jay D. Evans 《Behavioral ecology and sociobiology》1996,39(4):275-284
In many polygynous ant species, established colonies adopt new queens secondarily. Conflicts over queen adoption might arise
between queens and workers of established colonies and the newly mated females seeking adoption into nests. Colony members
are predicted to base adoption decisions on their relatednesses to other participants, on competition between queens for colony
resources, and on the effects that adopted queens have on colony survivorship and productivity. To provide a better understanding
of queen-adoption dynamics in a facultatively polygynous ant, colonies of Myrmica tahoensis were observed in the field for 4 consecutive years and analyzed genetically using highly polymorphic microsatellite DNA markers.
The extreme rarity of newly founded colonies suggests that most newly mated queens that succeed do so by entering established
nests. Queens are closely related on average (rˉ = 0.58), although a sizable minority of queen pairs (29%) are not close relatives. An experiment involving transfers of queens
among nests showed that queens are often accepted by workers to which they are completely unrelated. Average queen numbers
estimated from nest excavations (harmonic mean = 1.4) are broadly similar to effective queen numbers inferred from the genetic
relatedness of colony members, suggesting that reproductive skew is low in this species. Queens appear to have reproductive
lifespans of only 1 or 2 years. As a result, queens transmit a substantial fraction of their genes posthumously (through the
reproduction of related nestmates), in comparison to direct and indirect reproduction while they are alive. Thus queens and
other colony members should often accept new queens when doing so will increase colony survivorship, in some cases even when
the adopted queens are not close relatives.
Received: 20 February 1996/Accepted after revision: 25 May 1996 相似文献
99.
Methods for life cycle assessment of products (LCA) are most often based on the general prevention principle, as opposed to the risk minimization principle. Here, the desirability and feasibility of a combined approach are discussed, along with the conditions for elaboration in the framework of LCA methodology, and the consequences for LCA practice. A combined approach provides a separate assessment of above and below threshold pollution, offering the possibility to combat above threshold impacts with priority. Spatial differentiation in fate, exposure, and effect modelling is identified to play a central role in the implementation. The collection of region-specific data turns out to be the most elaborate requirement for the implementation in both methodology and practice. A methodological framework for the construction of characterization factors is provided. Along with spatial differentiation of existing parameters, two newly introduced spatial parameters play a key role: the sensitivity factor and the threshold factor. The practicability of the proposed procedure is illustrated by an example of its application. Providing a reasonable data availability, the development of separate LCA characterization factors for the respective assessment of pollution levels above and below environmental threshold values seems to be a feasible task that may add to LCA credibility. 相似文献
100.