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911.
912.
At present, gas hydrates are known to occur in continental high latitude permafrost regions and deep sea sediments. For middle latitude permafrost regions of the Tibetan Plateau, further research is required to ascertain its potential development of gas hydrates. This paper reviewed pertinent literature on gas hydrates in the Tibetan Plateau. Both geological and ge- ographical data are synthesized to reveal the relationship between gas hydrate formation and petroleum geological evo- lution, Plateau uplift, formation of permafrost, and glacial processes. Previous studies indicate that numerous residual basins in the Plateau have been formed by original sedimentary basins accompanied by rapid uplift of the Plateau. Ex- tensive marine Mesozoic hydrocarbon source rocks in these basins could provide rich sources of materials forming gas hydrates in permafrost. Primary hydrocarbon-generating period in the Plateau is from late Jurassic to early Cretaceous, while secondary hydrocarbon generation, regionally or locally, occurs mainly in the Paleogene. Before rapid uplift of the Plateau, oil-gas reservoirs were continuously destroyed and assembled to form new reservoirs due to structural and thermal dynamics, forcing hydrocarbon migration. Since 3.4 Ma B.P., the Plateau has undergone strong uplift and extensive gla- ciation, periglacier processes prevailed, hydrocarbon gas again migrated, and free gas beneath ice sheets within sedi- mentary materials interacted with water, generating gas hydrates which were finally preserved under a cap formed by frozen layers through rapid cooling in the Plateau. Taken as a whole, it can be safely concluded that there is great temporal and spatial coupling relationships between evolution of the Tibetan Plateau and generation of gas hydrates. 相似文献
913.
中国土壤动物生态地理研究进展(英文) 总被引:7,自引:0,他引:7
This review summarizes main research findings in soil fauna eco-geography in China in the past 30 years.The subject areas and main results were overviewed including biodiversity and eco-geological distribution of soil fauna communities.Studies of ecological distributions of soil fauna and dynamic ranges in space from tropical,subtropical to temperate regions,and in categories from forest,grassland,desert,wetland,farmland to urban ecosystems,the responses and indications of soil fauna to soil environments.Ef... 相似文献
914.
915.
Feng She YiFan Cheng ShiGong Wang YongTao Guo JinYan Wang MinJing M KeZheng Shang 《寒旱区科学》2011,3(3):0252-0263
Although Lanzhou is one of the most heavily polluted cities in China, the composition of its air pollutants have not yet been studied in detail. The data of four months on the concentrations and compositions of ions from daily air-filter samples in the winter and spring during 2007–2008 were analyzed to investigate temporal trends and their possible causes. The results indicate that mean concentrations of almost all the aerosol components are greater in winter than in spring due to stronger emissions in winter and weaker localized dispersion. Spring dust storms are the major cause of the highest peak PM10 concentrations recorded during the study period; however, these elevated levels were transient. Ion concentrations related to coal combustion show the greatest reduction from winter to spring, while the concentrations of strong crustal components show a less-pronounced reduction. Strong cycles in the levels of particulate matter (PM) and all ions are also observed during the winter months due to meteorological conditions. Depending on the season, nine different ions accounted for 20%–50% of the PM concentration. The particle size of polluting ions was constant at times of increasing PM concentrations (particularly during winter), whereas the particle size of crustal ions increased dramatically during spring dust storms. Local meteorological conditions (especially wind speed) have a strong influence on the levels of pollutants. Four dust storms were noted, including one during winter. In summary, the regional transport of desert dust from the Gobi can significantly affect air quality and the chemical composition of aerosols in Lanzhou. The dust storms can strongly increase concentration of crustal ions, which are characteristics of deserts in northwestern China. This observation is in agreement with back-trajectories, which show reduced levels of pollutant ions during dust storms. Data on nitrate:sulfate ratios indicate that stationary point sources are the main source of ions rather than mobile sources. 相似文献
916.
917.
经济发展速度一直是各国家经济发展水平的重要测度指标,但国家经济增速与国家竞争/影响力之间的关系及可能的阈值需要进行深入地研究,尤其是在中国经济增速下滑的背景下,迫切需要阐释经济增速下降是否影响国家竞争力/影响力。在评述既有研究进展的基础上,采用时空分析路径,探讨国家经济发展速度与国家竞争力/影响力的时空关系。首先,从历史的角度分析了15世纪以来世界权力中心的演变路径,考察了英国、美国等世界权力中心的国家经济增速变化,总结其发展规律,考察国家影响力与国家经济增速之间的对应关系。然后着眼于空间视角,考察目前国家经济增速与国家竞争力的空间分异,尤其是考察两者之间关系的分异关系,总结主要特征与规律。研究发现国家经济增速与国家影响力之间并非存在严格的线性关系,但国家影响力的培育与强化仍需要一定的经济增速进行支撑,而国家经济增速与国家竞争力之间呈现逆向的对应关系,经济高速增长的国家往往竞争力较低,竞争力较高的国家往往有较低的经济增速甚至负增长。 相似文献
918.
乡村振兴战略背景下,中国乡村进入转型发展的关键阶段,探索不同地域类型的乡村振兴具体路径具有重要意义。以四川省为例,构建县域乡村地域功能评价指标体系,研究县域经济发展、粮食生产、社会保障和生态保育功能的空间差异,识别各县域主导功能和短板功能,探索各类型区差异化的乡村振兴路径。结果表明:1)四川省乡村地域功能空间格局分异特征明显。经济发展功能和社会保障功能的地带性规律基本一致,均呈现由川东南向川西北逐渐减弱的分异格局,粮食生产功能在成都平原经济区和攀西安宁河流域的空间集聚特征明显,生态保育功能则呈现由川东南向川西北逐渐增强态势。2)以主导功能和短板功能为划分原则,将四川省划分为主导发展型、极化发展型和综合发展型三大类,并根据不同地域类型提出乡村振兴的实施路径:主导发展型应优先发挥主导功能,同时整合协调其他功能,带动乡村振兴全面发展;极化发展型在发挥其优势功能的同时需补齐短板,实现基本均衡发展;综合发展型依托现有基础,实现产业再升级,促进产城融合,成为四川省乡村振兴发展引领示范区。 相似文献
919.
Attribution analysis for water yield service based on the geographical detector method: A case study of the Hengduan Mountain region 总被引:1,自引:0,他引:1
Ecosystem services, which include water yield services, have been incorporated into decision processes of regional land use planning and sustainable development. Spatial pattern characteristics and identification of factors that influence water yield are the basis for decision making. However, there are limited studies on the driving mechanisms that affect the spatial heterogeneity of ecosystem services. In this study, we used the Hengduan Mountain region in southwest China, with obvious spatial heterogeneity, as the research site. The water yield module in the In VEST software was used to simulate the spatial distribution of water yield. Also, quantitative attribution analysis was conducted for various geomorphological and climatic zones in the Hengduan Mountain region by using the geographical detector method. Influencing factors, such as climate, topography, soil, vegetation type, and land use type and pattern, were taken into consideration for this analysis. Four key findings were obtained. First, water yield spatial heterogeneity is influenced most by climate-related factors, where precipitation and evapotranspiration are the dominant factors. Second, the relative importance of each impact factor to the water yield heterogeneity differs significantly by geomorphological and climatic zones. In flat areas, the influence of evapotranspiration is higher than that of precipitation. As relief increases, the importance of precipitation increases and eventually, it becomes the most influential factor. Evapotranspiration is the most influential factor in a plateau climate zone, while in the mid-subtropical zone, precipitation is the main controlling factor. Third, land use type is also an important driving force in flat areas. Thus, more attention should be paid to urbanization and land use planning, which involves land use changes, to mitigate the impact on water yield spatial pattern. The fourth finding was that a risk detector showed that Primarosol and Anthropogenic soil areas, shrub areas, and areas with slope 5° and 25°–35° should be recognized as water yield important zones, while the corresponding elevation values are different among different geomorphological and climatic zones. Therefore, the spatial heterogeneity and influencing factors in different zones should be fully con-sidered while planning the maintenance and protection of water yield services in the Hengduan Mountain region. 相似文献
920.
中国区域信息空间和人口空间的耦合关联分析 总被引:1,自引:0,他引:1
从流动空间角度出发,建立基于关系测度的空间耦合模型,采用复杂网络分析方法和灰色关联分析方法深入探讨区域信息空间和人口空间的耦合格局。研究发现信息空间和人口空间的耦合网络呈现“核心-边缘”模式,北京、上海、广东、天津、新疆和甘肃等耦合核心省市在整个省市内占据主导地位,是其他省市耦合发展所依附的核心。全国省市信息空间和人口空间耦合分布的总体布局呈现“川”型特征,分为高耦合协调型、中耦合磨合型以及低耦合发展型。信息空间和人口空间的耦合主要分为高耦合协调型、中耦合磨合型以及低耦合发展型3种,其中空间的高耦合程度一方面响应了国家加快推进互联互通建设的发展战略,另一方面也是京津冀一体化以及建设丝绸之路经济带的必然结果。 相似文献