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891.
中国自然资源政策演进历程与发展方向 总被引:2,自引:0,他引:2
自然资源政策是国家政策体系的重要组成部分,其社会关注度、复杂性、地区差异性等特征较为突出.1980年代以来,中国自然资源政策大致经历了上世纪80年代、1991-1997、1998-2003、2004 - 2010等四个阶段的演进,期间,社会经济发展形势不断发展变化,自然资源政策的需求和目标也不断变化,并为社会经济快速发展提供了政策基础;但同时也在政策一致性、政策权威性、政策公正性、政策认知性等方面,暴露出一些不足和缺憾.自2011年开始,资源政策的演进进入了第五个阶段.展望未来,为全面落实科学发展观和加快转变经济发展方式,中国自然资源政策应不断创新,重点在政府规制、全面负责、促进转型、系统协调和差异设计等方面不断优化和发展. 相似文献
892.
Burial of terrestrial and marine organic carbon in Jiaozhou Bay: different responses to urbanization 总被引:3,自引:0,他引:3
Yang Liyang Wu Ying Zhang Jing Liu Sumei Deng Bing 《Regional Environmental Change》2011,11(3):707-714
Organic geochemical proxies (OC, OC/TN, δ13C, and lignin oxidation products) were measured in a 271 cm long sediment core collected from central Jiaozhou Bay, northern
China, to study the response of terrestrial and marine organic carbon burials to the surrounding urbanization. Terrestrial
organic carbon content was constantly low from the bottom of the core to ~150 cm depth, indicating a stable and low level
of terrestrial input before urbanization. Thereafter, it increased up to ~20 cm depth, suggesting that increased human activities
and land-use changes during urbanization likely enhanced the flux of terrestrial organic carbon to the bay. Overall, 5–38%
of the total organic carbon was terrigenous, which was derived from a mixture of woody and non-woody angiosperms and moderately
degraded. Marine organic carbon content did not increase notably during urbanization. It increased from the bottom of the
core to ~180 cm and stayed at high levels until it decreased in the top 20 cm. It was affected by multiple factors, including
grain size and nutrient composition. These results demonstrate the different influences of urbanization on terrestrial and
marine organic carbon cycles and suggest the importance of discriminating between these two organic carbon pools in the reconstruction
of their historical changes. 相似文献
893.
In this study, aerobic granules were cultivated in sequencing batch reactors with activated sludge as the seed. The reactors were operated for 12 h per cycle with the organic loading rate (OLR) increasing in double stepwise from 0.5 to 4.0 g COD L−1 d−1. Within the 40 d running, black granules with regular and smooth morphology were cultivated, which had high wet density and high settling velocity. During the granulation process, foams emerged and disappeared in the reactor, coinciding with the proliferation of filamentous microorganisms in the granules, implying that surfactants might exist and play an important role in the granulation. Using ultra performance liquid chromatography-tandem mass spectrometry, the surfactants were identified as homologous compounds of polyethylene glycol (PEG) with molecular weights ranging mainly from 100 to 500 Da. Their general formulas were proposed as HO-[CH2-CH2-O]n-H. The source of PEG still needs further investigation. 相似文献
894.
Phosphorus (P) is a key biological element and limiting nutrient in aquatic environments. Phosphate (+5) is traditionally associated with the P nutrient supply. However, phosphite (+3) has recently generated a great deal of interest, because of the possibility that it is a P source based on recognition of its vital role in the original life of the early earth. This study investigated whether phosphite can be an alternative P source for Microcystis aeruginosa PCC 7806, one of the predominant bloom species in freshwater systems. The results indicated that M. aeruginosa could not utilize phosphite as a sole P-nutrient directly for cell growth at any concentration, but that phosphite could boost cell numbers and chlorophyll a (Chl-a) content as long as phosphate was provided simultaneously. Specifically, Chl-a production increased sharply when 5.44 mg P L−1 phosphite was added to 0.54 mg P L−1 phosphate medium. Analysis of the maximum yield of PSII indicated that phosphite may stimulate the photosynthesis process of cells in phosphate-phosphite medium. In addition, phosphite failed to support cell growth, even though it more readily permeated the cells in P-deficient medium than in P-sufficient medium. Alkaline phosphatase activity (APA) analysis indicated that, unlike organic P, phosphite inhibits the response of cells to deficient P status, especially under P-deprived conditions. 相似文献
895.
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897.
Bing Xue Yong Geng Wan-xia Ren Zi-long Zhang Wei-wei Zhang Chen-yu Lu Xing-peng Chen 《Journal of Material Cycles and Waste Management》2011,13(4):283-292
Rapid industrialization and urbanization in developing countries have created serious problems in municipal solid waste (MSW)
management. New case studies can shed light on these problems and point the way to potential solutions for improving the overall
eco-efficiency of MSW management. This paper employs a case study approach, analyzing MSW management in Inner Mongolia. This
study encompasses all aspects of MSW management, including collection, separation, recycling, and disposal. Problems and challenges
are identified through our analysis, and recommendations are raised by considering the local realities. Our main findings
are: (1) while large cities have already established a solid foundation for MSW management, small- and medium-sized cities
deserve more attention; (2) MSW in rural areas is even worse than urban areas; (3) enforcement of MSW regulations is ineffective
and needs improvement; (4) lack of funds, R&D efforts and advanced technologies have impeded sustainable MSW management; (5)
lack of coordination and communication among different stakeholders further damages the efforts for improvement of MSW management.
Therefore, integrated efforts that combine the above concerns should be initiated so that the overall effectiveness and efficiency
of MSW management can be improved. 相似文献
898.
高强度Q460钢材高温力学性能试验研究 总被引:3,自引:0,他引:3
采用恒温拉伸法和振动法分别对国产高强度Q460钢材在高温下的强度和弹性模量进行了试验研究。根据试验结果对屈服强度、极限强度和弹性模量进行了拟合,得到了Q460钢材的力学性能指标随温度变化的函数表达式。将Q460钢的高温力学性能指标和普通结构钢进行了对比。研究结果表明:高强度Q460钢材的强度和弹性模量随温度的升高而降低;Q460钢材高温下的强度折减系数比普通钢低,同等条件下,Q460钢结构比普通钢结构具有较好的抗火性能。 相似文献
899.
通过分析1994~2009年16 a逐年DMSP/OLS的静态平均灯光数据的DN值分布情况,考虑实际空间格局分布数据需求和数据质量,选择1994、2000、2005、2009年4个年度为代表,进行江西省城镇空间格局分布应用研究,并对数据质量进行评价。结果表明:1994~2009年度江西省城镇建设用地总量数值尽管与统计数据之间存在一定的波动,但总体扩展趋势基本一致;在城镇化增长速度上,2000~2005年比1994~2000年大29.53%,2005~2009年比1994~2000年大4357%,说明江西省城镇化发展正逐步提速,并有加快发展的趋势;景观指数分析表明江西省城镇化扩张过程中,面积越来越大,城镇间聚集度越来越高,相互影响也越来越大;城镇化形状越来越复杂;城镇间联系越来越紧密,破碎度逐步减小,城镇斑块形状变化逐步加大,发展无序程度加重。最后,针对江西省城镇空间格局发展现状,研究提出了积极发展中型城市、集约化发展特大城市、稳步扩大小城镇发展规模的建议 相似文献
900.
Yong Geng Wan-xia Ren Bing Xue Tsuyoshi Fujita Feng-ming Xi Ye Liu Mei-ling Wang 《Journal of Material Cycles and Waste Management》2013,15(3):310-320
Medical waste management is of great importance due to its potential environmental and public health risks, especially in developing countries where both financial and technological resources on medical waste management are still lacking. Although many studies have focused on country-scaled medical waste management, few have paid close attention to regional (city-scale) management, particularly in China. This paper fills such a gap by employing a case study approach. Due to its representative nature, Shenyang was selected as the case study. After a review of China’s medical waste management, an empirical study in Shenyang was conducted in order to analyze the current state as well as identify key challenges on regional medical waste management. Based upon the local realities and aiming to better manage medical wastes, an integrated medical waste management framework is developed. Such a platform encourages the establishment of a specific medical waste management authority, a city scaled capacity building program on improving the general public’s awareness, an information platform, application of state-of-the-art technologies, as well as creation of an effective financial system. The combination of such initiatives can significantly improve the overall eco-efficiency of medical waste management at the regional level and should be promoted to other developing cities. 相似文献