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871.
High-tech industrial zone is an important carrier for constructing innovative cities. It also plays an important role in implementing the national independent innovative strategy. However, most of the high-tech industrial zones have many problems in their development process, such as efficiency of land use, weakness of oriented function and lack of land intensive. To solve these problems, the authors of this paper introduced the concept of land use performance and established the theoretical model to assess the land use performance of high-tech industrial zones. The model consists of the following three-dimensional parts: land use benefit, land use efficiency and innovative function. Based on this theory model, an index system which was composed of three secondary indictors, eight tertiary indictors and 37 fourth-grade indictors was set up to evaluate the land use performance of high-tech zone. To avoid the defects of plus model and function model, the authors brought out a three-dimensional evaluation model to examine the index of the land use performance of the high-tech industrial parks, which equals to the evaluation indicator system of land use performance of high-tech zone based on the above research. The authors examined the land use performance of five different high-tech industrial parks in Haidian District, Beijing City. The results indicated that the indicator system performs better in the aspect of evaluating land use benefit, land use efficiency and function of the high-tech industrial zone compared with other models. 相似文献
872.
Abstract The 11th Five Year Plan has divided national functional zones in the basic unit of county-level administrative region. After implementation of national Major Function-oriented Zones (MFOZ) at prefecture and county levels, the spatial development sequence must be specified, development intensity must be limited, oriented zones must be designated and “red line” areas of spatial governance must be defined. In view of the above, choosing a typical county area and exploring its functional zoning after orienting its major functions will supply reference for carrying out the national spatial planning in the 12th Five Year Period, and it will also provide experience for the study of function regionalization which is the theme of MFOZ in the present academic circles. In this paper, the authors take Shangyu County as an example to study the general principles, train of thought of county-level functional regionalization in development-optimized areas, and to explore its reasonable functional zoning plan. Consequently, the authors present five principles and suggest a function-oriented zoning plan with 2 levels and 4 types. 相似文献
873.
D.I. Kaplan D.I. Demirkanli D.M. Beals J.E. Halverson 《Journal of environmental radioactivity》2010,101(5):338-344
An 11-year lysimeter study was established to monitor the movement of Pu through vadose zone sediments. Sediment Pu concentrations as a function of depth indicated that some Pu moved upward from the buried source material. Subsequent numerical modeling suggested that the upward movement was largely the result of invading grasses taking up the Pu and translocating it upward. The objective of this study was to determine if the Pu of surface sediments originated from atmosphere fallout or from the buried lysimeter source material (weapons-grade Pu), providing additional evidence that plants were involved in the upward migration of Pu. The 240Pu/239Pu and 242Pu/239Pu atomic fraction ratios of the lysimeter surface sediments, as determined by Thermal Ionization Mass Spectroscopy (TIMS), were 0.063 and 0.00045, respectively; consistent with the signatures of the weapons-grade Pu. Our numerical simulations indicate that because plants create a large water flux, small concentrations over multiple years may result in a measurable accumulation of Pu on the ground surface. These results may have implications on the conceptual model for calculating risk associated with long-term stewardship and monitored natural attenuation management of Pu contaminated subsurface and surface sediments. 相似文献
874.
Land-use change in oases of arid zones play a significant role in the sustainable development and stability of oases. This paper presents a typical case of successful efforts to mitigate land-use change, its drivers and effects on the oasis eco-environment at Keriya Oasis in the western arid zone of China using remotely-sensed data, official statistics, and data collected by field investigation. Mathematical models were developed to quantify important elements related to land-use change, including net change and total change. The results indicate that: (1) approximately 17% of land-use types of Keriya Oasis changed between 1991 and 2002; (2) socioeconomic development, climate change, and economic polices contributed to land-use change in the oasis; (3) inappropriate human activities were the main cause of land-use change and eco-environmental degradation in the oasis; and (4) the stability of the oasis is threatened by land-use change and unexpected eco-environmental changes in the oasis and oasis–desert ecotone. The study suggests irrational human activity in arid zones, and that caution should be exercised to maintain stability and sustainable development of oases. 相似文献
875.
876.
开发区协调发展规划研究——以本溪经济技术开发区为例 总被引:1,自引:0,他引:1
本文对如何制定开发区的协调发展规划,提出了以可持续发展思想为指导,以环境承载力为社会经济和环境协调发展的判据的研究思路,并以本溪经济技术开发区生态建设和环境综合规划为例进行了案例分析,验证了这一思路的可行性和合理性。 相似文献
877.
The pyrophytic properties of the larch Larix gmelinii (Rupr.) Rupr. growing in the northern taiga of central Siberia have been studied. It has been found that, although the trees are highly combustible and fire resistance of tree stands is low, the species is highly pyrophytic, which allows it to retain its geographic range. At early stages of postfire successions, the larch exhibits characteristics of pyrogenic explerent and is subject to r-selection. When forest restoration is close to completion, the species passes into the patient state and acquires properties subject to K-selection. 相似文献
878.
土壤组分对磷形态和磷吸附-解吸的影响——基于三峡库区消落带落干期土壤 总被引:1,自引:0,他引:1
通过选择性去除土壤组分的方法,探讨了三峡库区消落带落干期3种典型土壤中有机质、铁氧化物组分对磷形态和磷吸附-解吸的影响.结果发现,三峡库区消落带落干期3种典型土壤去除的有机质以易氧化组分为主,去除有机质后,土壤中各种磷形态的含量变化较小.然而,去除游离铁氧化物后,土壤中各种磷形态的含量均发生明显降低.同时,去除有机质、游离铁氧化物组分后并未改变土壤中各种磷形态的相对大小顺序,均为:钙结合磷(Ca-P) > 有机磷(OP) > 铁/铝结合磷(Fe/Al-P).此外,黄壤(FJ)、紫色潮土(KX)和灰棕紫泥(FL)去除有机质后对磷的吸附能力较原始土壤仅分别降低0.5%、2.3%、6.5%(P=0.017<0.05,显著性差异),表明3种土壤中有机质组分对磷吸附的影响较小;而去除游离铁氧化物后对磷的吸附能力分别降低45.6%、51.7%、43.9%(P=0.004<0.05,显著性差异),表明土壤中游离铁氧化物组分是决定磷吸附大小的重要因素.另外,3种土壤去除游离铁氧化物后较原始土壤吸附磷的解吸能力明显增加,表明游离铁氧化物组分是控制3种土壤吸附磷的解吸的重要因素.FL土壤去除有机质组分后较原始土壤吸附磷的解吸能力略有降低,而KX和FJ土壤去除有机质组分后较原始土壤吸附磷的解吸能力无明显差异,表明有机质组分对土壤吸附磷的解吸的影响与土壤类型有关. 相似文献
879.
Restoration processes of pollution zones in Hanjiang River 总被引:1,自引:1,他引:1
RestorationprocessesofpollutionzonesinHanjiangRiver¥ShenYunfen;TanYuyun;FengWeisong;GuManru(InstituteofHydrobiology,ChineseAc... 相似文献
880.
Removal of NAPLs from the unsaturated zone using steam: prevention of downward migration by injecting mixtures of steam and air 总被引:1,自引:0,他引:1
Steam injection for remediation of porous media contaminated by nonaqueous phase liquids has been shown to be a potentially efficient technology. There is, however, concern that the technique may lead to downward migration of separate phase contaminant. In this work, a modification of the steam injection technology is presented, where a mixture of steam and air was injected. In two-dimensional experiments with unsaturated porous medium contaminated with nonaqueous phase liquids, it was demonstrated how injection of pure steam lead to severe downward migration. Similar experiments, where steam and air were injected simultaneously, resulted in practically no downward migration and still rapid cleanup was achieved. The processes responsible for the prevention of downward migration when injecting steam-air mixtures were analyzed using a nonisothermal multiphase flow and transport model. Hereby, three mechanisms were identified and it was demonstrated how the effectiveness of these mechanisms depended on the air-to-steam mixing ratio. 相似文献