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The environmental sustainability of a fish farm rearing process was examined by means of emergy analysis. Many emergy analyses integrate data for a whole year smoothing short term variations and sometimes losing meaningful information (aliasing). For this reason we developed a model for an instantaneous emergy evaluation in an aquacultural system so that transformities, efficiency and effort spent at each moment during the fish rearing activity could be calculated. By means of the model and dynamic emergy calculations it is possible to recognize step by step the importance of the various emergy contributions and verify where and when to modify the system to move toward optimum production of a sustainable product. By the application of the model we confirmed that the emergy trends in a fish farm installation follow wide oscillations during a year due to variations in both internal and external emergy contributions. Among the fluxes considered, those due to the introduction of fingerlings represented the highest contributions to the total emergy budget. Thus, to improve the sustainability of the analyzed system the amount, frequency and timing of these fluxes must be carefully considered. For this purpose, a comparison between two different fry introduction schedules was performed to evaluate differences in the efficiency of the rearing process. 相似文献
995.
Teofilo Vamerali Marianna Bandiera Federica Zanetti Giuliano Mosca 《Environmental pollution (Barking, Essex : 1987)》2009,157(3):887-894
At a site in Udine, Italy, a 0.7 m layer of As, Co, Cu, Pb and Zn contaminated wastes derived from mineral roasting for sulphur extraction had been covered with an unpolluted 0.15 m layer of gravelly soil. This study investigates whether woody biomass phytoremediation is a realistic management option. Comparing ploughing and subsoiling (0.35 m depth), the growth of Populus and Salix and trace element uptake were investigated in both pot and field trials. Species differences were marginal and species selection was not critical. Impaired above-ground productivity and low translocation of trace elements showed that bioavailable contaminant stripping was not feasible. The most significant finding was of coarse and fine roots proliferation in surface layers that provided a significant sink for trace elements. We conclude that phytostabilisation and effective immobilisation of metals and As could be achieved at the site by soil amelioration combined with woody species establishment. Confidence to achieve a long-term and sustainable remediation requires a more complete quantification of root dynamics and a better understanding of rhizosphere processes. 相似文献
996.
Sustainable development is one of the most important ideas, and goals of our time. It is defined as "development which meets the needs and aspirations of the current generation and develops safe and sound society for future generation". Achieving sustainable development thus involves a vigorous and urgent debate on different dimensions. The different dimensions of sustainability as a framework involve all issues such as science, technology, economic growth and development, health, education, finance investment and trade, politics, natural disasters, population growth and terrorism, etc. No single dimension is responsible to develop sustainable society. This article mainly described the integrated relationship among the three dimensions ofsustainability. 相似文献
997.
Conservation subdivision design has been promoted as a way to protect ecologically sensitive areas while maintaining housing densities comparable to standard subdivisions, but many developers and planners question the appeal of conservation design to consumers. This study was conducted to compare economic aspects of conservation subdivision design to standard subdivision design in the midwestern United States. Three methods were used to determine the value homebuyers have for embedded conservation features in residential areas: transactional analyses (to indicate the value homebuyers have expressed for such features in the past); hedonic analyses (to determine the proportion of present value of homes attributable to such features); and contingent valuation (to examine willingness to pay according to homebuyers' preferred features, an indicator of potential future investment). Transactional analyses were based on assessment and transaction data for homes in three conservation-oriented subdivisions and three standard subdivisions in Cedar Rapids, Iowa, United States. Hedonic price models were also derived from assessment and transaction data. Contingent valuation analyses were based on a survey of residents in the same six subdivisions. Transactional data indicated higher 5-year appreciation rates for conservation versus standard subdivision design. Hedonic price models revealed that well-integrated conservation features (e.g. protected stream corridors) within subdivisions have a positive effect on home prices. Sixty-six percent of all respondents indicated willingness to pay for more embedded open space. Maximum willingness to pay was related to several factors including income, gender, desired level of open space, and concern about urban development. Overall, these results indicate that consumer demand and willingness to pay for conservation subdivision design are positive and should not be considered a barrier to implementation. 相似文献
998.
氧化亚铁硫杆菌的筛选、生长特性及其橡胶再生研究 总被引:3,自引:0,他引:3
从大西洋底死火山口土壤中筛选出一株硫杆菌,经16S rDNA鉴定为氧化亚铁硫杆菌。研究了初始底物Fe2+浓度,初始pH,接种量对其生长的影响,确定了其最佳的生长的条件:在30℃、170 r/min条件下,最适底物Fe2+浓度为9 g/L,最佳初始pH为2.5,最适接种量为10%(体积分数)。探讨了氧化亚铁硫杆菌对天然硫化橡胶的脱硫再生,橡胶的SEM分析、FTIR图谱及EDS图谱研究表明氧化亚铁硫杆菌对硫化胶粉的硫交联键有断裂或转化作用,脱硫率达52.6%,氧化亚铁硫杆菌对天然橡胶具有一定的再生作用。 相似文献
999.
人口问题是我国的基本问题,人口老龄化是人类的必然发展过程。随着人口老龄化的加剧,关注老年人、发展老龄产业逐渐成为社会发展的焦点。与此同时,互联网的普及使人们对电子商务由陌生到熟知,互联网已不再成为年轻人的专利,越来越多的老年人也加入到网民的行列。随着社会的进步和科技的发展,人口老龄化与电子商务作为两种必然趋势,备受人们关注。人口老龄化与电子商务之间究竟有什么关系,它们怎样相互影响的?本文将通过建立二者的关系模型,从定性的角度对此问题进行分析。 相似文献
1000.
税收竞争、财政分权与环境污染的关系研究一直是学术界研究的焦点问题之一。本文首先在Davoodi和Zou(1998)模型基础上将环境污染强度和环境质量分别引入生产函数和效用函数,讨论了税收竞争、财政分权与环境质量的长期动态关系,通过Hamilton函数得到了环境质量与税收竞争、财政分权的显式解,并通过求偏导数得到了税收竞争、财政分权与环境质量的关系,结果发现税收竞争、财政分权对环境质量均呈现显著的负向影响。然后,为了验证理论结果在实际经济中的适应性,利用中国2003-2012年30个省的面板数据,分析了税收竞争、收入分权是否会显著的影响环境污染,通过单位根检验和协整检验,发现税收竞争、收入分权与环境污染存在协整关系,即存在长期稳定的均衡关系,通过静态和动态面板数据模型的回归分析,发现税收竞争和收入分权均会加剧环境污染程度,且这两种面板数据模型得出的回归结果基本一致,进一步佐证了理论结果的正确性。同时在此研究基础上引入税收竞争与收入分权的交叉项,研究收入分权框架下的税收竞争与环境污染的内在联系,结果表明税收竞争通过分权通道对环境污染的影响被加强,进一步验证了命题1的正确性。此外,在实证研究中引入地区虚拟变量,对税收竞争与环境污染的关系进行区域差异性分析,结果表明税收竞争对环境污染的影响呈现区域性差异,在东部地区,税收竞争有益于环境污染的改善,而在中、西部地区,税收竞争却加剧了环境污染。因此,为社会计划者制定改善中国环境的政策提供了参考。 相似文献