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211.
212.
Surface sediments of the lagoons of Lomé, Togo, were analyzed for mercury, methylmercury, and trace elements. Concentrations
were greater than typical for natural lagoon sediments, and with greater variability within the Eastern lagoon compared to
the Western one. The Eastern lagoon is larger and has been dredged in the past, while the Western lagoon, which also receives
major waste inputs, has not been dredged and shows less tidal flushing. Accordingly, one naturally believes that the Eastern
lagoon is cleaner and probably safe to use due to its natural resources, including fishes to eat. Unexpectedly, we describe
here that mercury methylation was greater in the Eastern lagoon, indicating increased bioavailability of mercury, as probably
facilitated by past dredging that decreased solid-phase retention of inorganic mercury. Urbanization has historically been
more developed in the southern part of the lagoons, which is still reflected in contamination levels of sediment despite dredging,
probably because sources of contamination are still more important there today. Such urban contamination emphasizes the need
to regulate waste discharges and possible airborne contamination in growing cities of developing countries, and implements
environmental and public health monitoring, especially in relation to misbelieves systematically associated with the cleansing
effect of dredging activity. 相似文献
213.
Mo bioaccumulation in the earthworm Eisenia andrei was determined after 28 d exposure in ten different European field soils (pH 4.4-7.8) and an artificial soil, freshly spiked with Na2MoO4 at concentrations between 3.2 and 3200 mg Mo kg−1 dry soil. Three field soils were also tested after ageing for 11 months. Earthworm Mo concentrations generally levelled off at high exposure levels but in most soils showed a (nearly) linear increase with increasing soil concentrations in the lower, non-toxic range (below EC10 or NOEC for reproduction effects). Bioaccumulation (BAF) and Bioconcentration factors (BCF) were calculated as the ratio of earthworm concentration to soil and estimated porewater concentrations, respectively. BAFs (0.35-3.44) and BCFs (1.31-276) did not seem much affected by soil concentration, suggesting that earthworms are not capable of regulating their internal Mo concentrations. BAF was best predicted by ammonium oxalate-extractable iron (Feox) and phosphor (Pox) contents of the soils. 相似文献
214.
中国并网光伏发电系统的经济性与环境效益 总被引:2,自引:0,他引:2
太阳能已成为世界各国公认的最为理想的替代能源,其应用规模不断扩大.但光伏发电系统高昂的成本,成为限制其发展的关键因素.本文应用净现值和单因素敏感性分析工具,建立了光伏发电成本的计算模型,以我国34个省会城市作为研究案例,对井网光伏发电系统进行了经济性和环境效益分析.结果显示:在目前政府初始投资补贴一半的情况下,并网光伏发电成本介于0.83-2.29元/kWh之间.即便在光照资源最丰富的地区,并网光伏发电仍无法与常规能源发电相竞争.在影响并网光伏系统发电成本的诸多影响因素中,政府初始投资补贴额度、水平面太阳能辐射量和投资密度的敏感性最强;CDM资金的注入对光伏发电成本的降低具有积极的作用.激励政策方面,出台合适的、稳定的上网电价对启动国内光伏市场最为有效.光伏发电系统的环境效益是指光伏发电的减排环境效益扣除系统发电环境成本的余额.经计算并网光伏发电具有显著的环境效益,其环境效益为0.0165元/kWh.本研究对于国家制定光伏发电的激励政策和成本分摊机制具有重要的参考价值. 相似文献
215.
Qiu Ling Fang Chuanglin Shen Yuming Liu Xiaoli .Institution of Geographic Sciences Natural Resources Research Chinese Academy of Sciences Beijing China; 《中国人口.资源与环境(英文版)》2011,(4):82-89
The five central cities-Beijing,Tianjin,Shanghai,Guangzhou and Shenzhen-of the three most important strategic regions in China,namely Beijing-Tianjin-Hebei metropolitan region,the Yangtze River Delta and the Pearl River Delta,are taken as a comparative analysis on urban producer services’ competitiveness,especially focusing on the comparative advantages and disadvantages of producer services in Beijing.Firstly,based on an integrated indicator system including one objective hierarchy,four standard hierarchies and 35 indicator hierarchies,the study applies factor analysis model and analytic hierarchy process model reformed by entropy technology to measure the comprehensive competitiveness of producer services in the above five cities.Secondly,Beijing has comparative advantages of capital resource,industrial base,scientific research resource and market scale,since it takes the first place of the five cities in the comprehensive competitiveness of producer services,the competitiveness of industrial development,business environment and living environment,only inferior to Shanghai in the competitiveness of talent capital.Thirdly,Beijing has comparative disadvantages in the level of producer services development,urban innovation capability and living environment.Finally,five proposals are put forth to enhance the competitiveness of producer services in Beijing,namely perfecting the system of laws and statutes,supporting the development of industry association,implementing scientific development planning,introducing preferential fiscal and taxation policies and strengthening human capital reserve. 相似文献
216.
基于WTA的湿地周边农户受偿意愿及影响因素研究 总被引:2,自引:1,他引:1
为了实现鄱阳湖湿地生态系统的可持续发展,促进公平合理的湿地保护局面的形成,对鄱阳湖湿地周边农户家庭生产生活的基本情况、生态环境的认知、以及基于禁渔期、保护候鸟和封洲禁牧等保护措施的生态补偿意愿进行了深入调查。结果表明:(1)鄱阳湖周边农户的家庭收入与湿地紧密相关,湖区农户具有一定的湿地生态环境认知和生态保护意识;(2)193份有效问卷中愿意接受补偿的比例高达881%,农户户均生态补偿意愿为3399元/(a·户),由此估算出鄱阳湖湿地生态补偿额约为每年582亿元;(3)Tobit回归模型的计量分析结果表明,农户的受偿意愿受年龄、生态效益的认知及生态保护态度的显著影响,研究认为提高农户的生态保护意识、对湖区农户进行合理的生态补偿是解决湿地保护与可持续发展问题的关键。 相似文献
217.
以县(市)作为研究单元,采用综合指数法,分别计算山东半岛城市群1986、2008年经济社会发展综合指数,通过比较各单元经济社会发展综合指数的变化,研究了20世纪80年代以来山东半岛城市群地区空间极化的特点;采用面板数据模型,定量探讨了山东半岛城市群地区空间极化的影响因素。研究表明:山东半岛城市群地区经济活动有明显的经济中心指向、沿海指向,空间发展依然以极化为主,新的发展极已经出现,但分布在区域的边缘地带,带动作用不大;大都市区整体规模加剧膨胀,核心和外围地区出现极化和反极化现象;东部地区出现网络化发展的雏形。原有经济基础、产业结构转换能力和经济全球化水平是改革开放以来山东半岛城市群地区空间极化的主要影响因素 相似文献
218.
The present work indentifies some environmental and health impacts of a municipal solid waste bio-drying plant taking into account the PCDD/F release into the atmosphere, its concentration at ground level and its deposition. Four scenarios are presented for the process air treatment and management: biofilter or regenerative thermal oxidation treatment, at two different heights. A Gaussian dispersion model, AERMOD, was used in order to model the dispersion and deposition of the PCDD/F emissions into the atmosphere. Considerations on health risk, from different exposure pathways are presented using an original approach. The case of biofilter at ground level resulted the most critical, depending on the low dispersion of the pollutants. Suggestions on technical solutions for the optimization of the impact are presented. 相似文献
219.
Martin Holmstrup Jesper G. SørensenJohannes Overgaard Mark BayleyAnne-Mette Bindesbøl Stine SlotsboKarina V. Fisker Kristine MaraldoDorthe Waagner Rodrigo LabouriauGert Asmund 《Environmental pollution (Barking, Essex : 1987)》2011,159(1):190-197
Stress originating from toxicants such as heavy metals can induce compensatory changes in the energy metabolism of organisms due to increased energy expenses associated with detoxification and excretion processes. These energy expenses may be reflected in the available energy reserves such as glycogen. In a field study the earthworm, Dendrobaena octaedra, was collected from polluted areas, and from unpolluted reference areas. If present in the environment, cadmium, lead and copper accumulated to high concentrations in D. octaedra. In contrast, other toxic metals such as aluminium, nickel and zinc appeared to be regulated and kept at low internal concentrations compared to soil concentrations. Lead, cadmium and copper accumulation did not correlate with glycogen reserves of individual worms. In contrast, aluminium, nickel and zinc were negatively correlated with glycogen reserves. These results suggest that coping with different metals in earthworms is associated with differential energy demands depending on the associated detoxification strategy. 相似文献
220.