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941.
以生态补偿试点区九洲江流域为例,基于调研数据和相关资料,以最小的政府生态补偿金额为目标,以水环境容量、耕地承载力、养殖户经济收益为主要约束,建立基于畜禽养殖模式转变的生态补偿空间优化模型.结果表明,九洲江流域生猪养殖最小生态补偿金为5.83亿元,其中2.92亿元用于55.47万头的生猪禁养,1.94亿元用于补助适养区内新建47.99万头高架网床模式养殖,0.97亿元用于18.57万头的养殖模式升级改造.优化后全流域养殖总规模为121.18万头,比现状减少约4万头.可实现污染物削减率73.66%,COD、总氮、总磷分别削减13980,2545,995t.其中,传统养殖模式全部被禁养或升级改造,高架网床养殖模式为流域最主要养殖模式,占比达到81.19%.10个镇的补偿资金及污染物削减情况存在显著差异,补偿金占比较高的是文地、良田、古城镇,合计占总补偿资金的56.78%,COD削减量占总削减量的55.35%.通过优化后的补偿方案,同时实现环境效益和经济效益的双赢. 相似文献
942.
目的研究飞艇蒙皮材料在临近空间环境下的力学特性。方法根据临近空间环境的特征参数,制定空间环境地面模拟实验方案,包括高低温、紫外环境和臭氧环境下地面模拟实验方案。然后以聚氨酯涂覆Nylon织物为例,研究临近空间环境对飞艇蒙皮材料力学特性的影响,并通过红外红外光谱和原子力显微镜研究其影响机理。结果与未经高低温循环相比,弹性模量增加了11%,拉伸强度的最大变化不超过5%;经过48~240h紫外线辐照后,弹性模量提高了22%~34%,拉伸强度几乎没有变化;通过臭氧老化后,材料弹性模量的增加幅值约为6%,拉伸强度逐渐降低。结论紫外辐射对于聚氨酯涂覆Nylon织物材料弹性模量的提升效应大于高低温和臭氧老化,但对其强度的影响明显小于高低温和臭氧老化,臭氧老化对材料强度影响大于高低温和紫外辐射。 相似文献
943.
中央广播电视发射塔环境电磁辐射测试研究 总被引:3,自引:0,他引:3
对发射7套电视节目和5套调频节目,发射总功率240KW的中央广播电视塔电磁辐射场强监测结果表明:(1)由于节目频率不同,发射机功率及发射天线形式、高度、增益不同,电磁波到达地面最大场强值的距离是不同的;在近距离内高层建筑各层所接收到的场强大小也是不同的。(2)电视与调频信号在近距离昼夜电平无明显变化。(3)电视塔周围2000米内环境综合场强最大值为284~328μW/cm2,所有环境测量值均小于公众导出限值40μW/cm2。 相似文献
944.
To investigate the suppression effect of charged water mist on gas explosion, a small charged water mist generator and a gas explosion simulation device were designed based on the principle of electrostatic induction. Experiments for testing characteristics of the gas explosion in a confined space under different charged polarities, charged voltages and mist fluxes were carried out. Experimental results indicated that, compared with the normal water mist, the explosion peak overpressure and the flame propagation speed could be more effectively reduced by the charged water mist. And this suppression effect could be promoted by increasing the charged voltage. To visualize the effect of the charged water mist's polarity on gas explosion, comparative experiments were conducted. The results showed that the explosion peak overpressure, the overpressure rising rate, and the propagation speed of the flame were reduced by 64.7%, 33.0% and 19.4%, respectively, when a +8 kV charged voltage was applied. In situation where a -8 kV charged voltage was applied, 64.1%, 26.5% and 16.0% reductions were achieved for the explosion peak overpressure, the overpressure rising rate, and the flame propagation speed respectively. Comparison of this data leads to the conclusion that the gas explosion could be more efficiently suppressed by the positively charged water mist. 相似文献
945.
John E. Fa Jesus Olivero Miguel Á. Farfán Ana L. Márquez Jesús Duarte Janet Nackoney Amy Hall Jef Dupain Sarah Seymour Paul J. Johnson David W. Macdonald Raimundo Real Juan M. Vargas 《Conservation biology》2015,29(3):805-815
We used data on number of carcasses of wildlife species sold in 79 bushmeat markets in a region of Nigeria and Cameroon to assess whether species composition of a market could be explained by anthropogenic pressures and environmental variables around each market. More than 45 mammal species from 9 orders were traded across all markets; mostly ungulates and rodents. For each market, we determined median body mass, species diversity (game diversity), and taxa that were principal contributors to the total number of carcasses for sale (game dominance). Human population density in surrounding areas was significantly and negatively related to the percentage ungulates and primates sold in markets and significantly and positively related to the proportion of rodents. The proportion of carnivores sold was higher in markets with high human population densities. Proportion of small‐bodied mammals (<1 kg) sold in markets increased as human population density increased, but proportion of large‐bodied mammals (>10 kg) decreased as human population density increased. We calculated an index of game depletion (GDI) for each market from the sum of the total number of carcasses traded per annum and species, weighted by the intrinsic rate of natural increase (rmax) of each species, divided by individuals traded in a market. The GDI of a market increased as the proportion of fast‐reproducing species (highest rmax) increased and as the representation of species with lowest rmax (slow‐reproducing) decreased. The best explanatory factor for a market's GDI was anthropogenic pressure—road density, human settlements with >3000 inhabitants, and nonforest vegetation. High and low GDI were significantly differentiated by human density and human settlements with >3000 inhabitants. Our results provided empirical evidence that human activity is correlated with more depleted bushmeat faunas and can be used as a proxy to determine areas in need of conservation action. 相似文献
946.
947.
T. R. McClanahan N. A. J. Graham M. A. MacNeil J. E. Cinner 《Conservation biology》2015,29(2):409-417
The failure of fisheries management among multispecies coral reef fisheries is well documented and has dire implications for the 100 million people engaged in these small‐scale operations. Weak or missing management institutions, a lack of research capacity, and the complex nature of these ecosystems have heralded a call for ecosystem‐based management approaches. However, ecosystem‐based management of coral reef fisheries has proved challenging due to the multispecies nature of catches and the diversity of fish functional roles. We used data on fish communities collected from 233 individual sites in 9 western Indian Ocean countries to evaluate changes in the site's functional composition and associated life‐history characteristics along a large range of fish biomass. As biomass increased along this range, fish were larger and grew and matured more slowly while the abundance of scraping and predatory species increased. The greatest changes in functional composition occurred below relatively low standing stock biomass (<600 kg/ha); abundances of piscivores, apex predators, and scraping herbivores were low at very light levels of fishing. This suggests potential trade‐offs in ecosystem function and estimated yields for different management systems. Current fishing gear and area restrictions are not achieving conservation targets (proposed here as standing stock biomass of 1150 kg/ha) and result in losses of life history and ecological functions. Fish in reefs where destructive gears were restricted typically had very similar biomass and functions to young and low compliance closures. This indicates the potentially important role of fisheries restrictions in providing some gains in biomass and associated ecological functions when fully protected area enforcement potential is limited and likely to fail. Our results indicate that biomass alone can provide broad ecosystem‐based fisheries management targets that can be easily applied even where research capacity and information is limited. Of particular value, is our finding that current management tools may be used to reach key ecosystem‐based management targets, enabling ecosystem‐based management in many socioeconomic contexts. 相似文献
948.
王海云 《长江流域资源与环境》1994,3(1):90-96
以宜昌市水环境保护规划研究专题为例,就长江宜昌段1993~2010年水环境保护规划进行了分析研究。首先对污染物排放量进行了预测,对长江宜昌段水环境容量进行了计算,然后划分出水环境保护功能分区和水质目标,提高综合治理水质污染符合实际的技术措施、工程措施和经济措施。 相似文献
949.
磷石膏作水泥缓凝剂的试验研究 总被引:2,自引:0,他引:2
介绍了磷石膏的主要化学成份,矿物组成和水泥 磷石膏的物理力学性能。它可以代替天然石膏作水泥缓剂加紧开发利用。 相似文献
950.
本文采用泛函分析的空间理论,以非线性数学工具来研究环境问题,采用系统聚类与自动优化的方法。进行城镇发展条件综合评价,在我国中东部地区生态环境现状调查中,对黑龙江省78个市进行评价收到满意效果。 相似文献