Neritic and pelagic carbonate sedimentation in the marine environment: ignorance is not bliss     

J. D. Milliman  A. W. Droxler 《International Journal of Earth Sciences》1996,85(3):496-504

Synthesis of available data allows us to define general patterns of late Quaternary carbonate production and sedimentation in the global ocean. During high stands of sea level, the neritic and pelagic environments appear to sequester approximately similar amounts of carbonate, whereas during low stands of sea level the decreased neritic zone produces and accumulates approximately an order of magnitude less carbonate. Assuming that global accumulation of deep-sea carbonates remains more or less constant during glacially induced changes in sea level, the ocean becomes depleted with respect to calcium carbonate during high stands and recharges during low stands. Before we can achieve a better understanding of the global carbonate system, however, we need a better understanding of key environments and processes: (a) production and accumulation on continental shelves both as potential sinks (accumulation) and as sources (export to the deep sea); (b) a better measure of pelagic carbonate production; and (c) late Quaternary (late Pleistocene and Holocene) mass accumulation rates in the deep sea.  相似文献   

农业气象与我国热区名特优水果生产   总被引：8，自引：0，他引：8  

钟思强  苏维佳 《热带地理》1996,16(3):204-211

龙眼、荔枝和果是我国热带、南亚热带（简称热区）名特优水果．这些水果的花芽分化、开花座果对气象条件要求较严格。本文在分析龙眼、荔枝和果的主要气候生态特性的基础上，结合有关省区的气候资料，作出龙眼、荔枝和果生产的布局区划。  相似文献   

青海盐湖资源综合利用   总被引：8，自引：4，他引：8       下载免费PDF全文

徐日瑶  刘宏专  刘荣义 《盐湖研究》2003,11(1):31-40

着重介绍了青海盐湖水氯镁石 (MgCl2 ·6H2 O)的综合利用。从水氯镁石中可开发的产品有金属镁、镁合金、多品种氧化镁、镁砂、高纯镁砂、轻质碳酸镁、多品种轻质氧化镁及镁水泥。根据青海盐湖的特点 ,探讨了生产上述产品 ,青海盐湖的水氯镁石 (MgCl2 ·6H2 O)按什么方法来生产是最佳方法的问题。  相似文献   

盐湖水氯镁石制取金属镁及高纯镁砂的生产技术   总被引：6，自引：1，他引：6       下载免费PDF全文

徐日瑶  刘宏专 《盐湖研究》2003,11(2):46-50

介绍了盐湖水氯镁石用溶剂络合 ,NH3 螯合结晶脱水 ,制取无水氯化镁 ,电解制镁技术。用螯合物(MgCl2 ·6NH3 )脱氨后的NH3 与MgCl2 溶液作用生产高纯镁砂 ;直接用NH3 与MgCl2 溶液作用生产高纯镁砂 ,副产的NH4Cl再与水氯镁石作用后制取铵光卤石 ,熔融脱氨后 ,无水氯化镁熔体电解制镁。这两种生产方法 ,对开发青海盐湖水氯镁石的综合利用是最佳工艺。  相似文献   

全球生产网络(GPN)的理论问题和中国实践启示     

陈蕊  刘逸 《地理研究》2021,40(12):3259-3271

全球生产网络理论（GPN）是关系经济地理学派的核心理论成果,但当前国内外研究对其发展脉络和理论内涵的认识存在模糊之处,在应用方面也存在一些误区。因此,本文从GPN与全球价值链（GVC）理论互动的视角出发,回顾GVC和GPN的重要发展阶段及对彼此的影响,针对常见的对GPN理解和应用的误区展开解释与辨析,主要得到3个结论。第一,GPN理论的研究目的已从解释“价值生产”凝练为解释“区域发展的不均衡”,更贴近经济地理学的基本研究范式。第二,GPN与GVC正在从分歧走向融合,共同致力于捕捉与解释全球化动态。第三,并非所有跨国公司研究或生产网络研究都属于GPN研究,GPN专指研究跨国公司与主要相关者基于生产所形成的网络动态,不适用于以国家为单位的研究,也不着力于揭示企业内部经营管理动态。本文继而指出中国经验既需要GPN理论加以探析、也有助于丰富GPN理论,精准理解GPN尤其对中国当前推行双循环战略有重要应用价值。本文强调,GPN作为中观理论框架,有效解释了全球经济中区域发展的多尺度动态,在全球化出现逆流的新形势下,对中国全球化实践,特别是国际国内双循环发展有着鲜明的研究意义。  相似文献   

校园控制点成果管理信息系统设计与实现     

隋铭明  束蝉方  陈健  王志杰 《现代测绘》2007,30(6):43-44,48

测量控制点成果管理信息系统是基础地理信息系统的重要组成部分，对于众多拥有测绘专业的高校来说，对校园内的控制点成果加以科学管理，为教师和学生及实验人员提供准确、高效的数据服务，是校园测量控制点成果管理信息系统建设的根本出发点。本文介绍了测量控制点的特点，研究设计了系统的总体架构、功能设计和数据组织，最后实现了集GIS功能于一体的图、文、表并茂的校园测量控制点成果管理信息系统。  相似文献   

Observations of C2 Molecules in the Coma of Comets at Mitaka     

Sekiguchi  T.  Watanabe  J.  Fukushima  H.  Yamamoto  T.  Yamamoto  N. 《Earth, Moon, and Planets》1997,78(1-3):143-148

In order to monitor the various phenomena of comets, we continuously made the near-nucleus imaging observations of comets at National Astronomical Observatory, Mitaka. Here we report on the results of the observations of two spectacular comets. One is the analysis of photometry of C₂ emission images in the coma of comet Hyakutake (C/1996 B2). By comparing the production rates of C₂ radicals with C₂H₂ molecules, we conclude that the most C₂ radicals were originated from C₂H₂, while some of them might be produced from other parents. The second item is the analysis of the morphology of C₂ emission images in the coma of comet Hale-Bopp(C/1995 O1). By applying a ring masking technique, we detected asymmetrical distribution of the C₂ molecules. The results of these two comets might suggest that a portion of C₂ radicals were formed by the disintegration of the small organic dust grains, like the so-called CHON particles. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Abundance, Biomass, Production and Trophic Roles of Micro- and Net-Zooplankton in Ise Bay, Central Japan, in Winter     

Shin-Ichi Uye  Naoki Nagano  Tetsuya Shimazu 《Journal of Oceanography》2000,56(4):389-398

We investigated the geographical variations in abundance and biomass of the major taxonomic groups of micro- and net-zooplankton along a transect through Ise Bay, central Japan, and neighboring Pacific Ocean in February 1995. The results were used to estimate their secondary and tertiary production rates and assess their trophic roles in this eutrophic embayment in winter. Ise Bay nourished a much higher biomass of both micro- and net-zooplankton (mean: 3.79 and 13.9 mg C m^–3, respectively) than the offshore area (mean: 0.76 and 4.47 mg C m^–3, respectively). In the bay, tintinnid ciliates, naked ciliates and copepod nauplii accounted for, on average, 69, 18 and 13% of the microzooplankton biomass, respectively. Of net-zooplankton biomass, copepods (i.e. Acartia, Calanus, Centropages, Microsetella and Paracalanus) formed the majority (mean: 63%). Average secondary production rates of micro- and net-zooplankton in the bay were 1.19 and 1.87 mg C m^–3d^–1 (or 23.1 and 36.4 mg C m^–2d^–1), respectively, and average tertiary production rate of net-zooplankton was 0.75 mg C m^–3d^–1 (or 14.6 mg C m^–2d^–1). Available data approximated average phytoplankton primary production rate as 1000 mg C m^–2d^–1 during our study period. The transfer efficiency from primary production to zooplankton secondary production was 6.0%, and the efficiency from secondary production to tertiary production was 25%. The amount of food required to support the zooplankton secondary production corresponded to 18% of the phytoplankton primary production or only 1.7% of the phytoplankton biomass, demonstrating that the grazing impact of herbivorous zooplankton was minor in Ise Bay in winter.  相似文献   

中国现阶段产业结构的地域差异研究   总被引：2，自引：0，他引：2  

李晖  汤进华 《热带地理》2003,23(4):350-353

研究了我国省级行政单位和东、中、西部地区的产业结构(就业结构和产值结构),并与全国和国际比较.结果表明,全国各省(直辖市、自治区)产业结构呈多样化特征;②全国各省(直辖市、自治区)就业结构的基本形式为"一三二"型,产值结构的基本形式为"二三一"型,表明产业结构不尽合理,从就业结构与产值结构的产投比看,第二产业效益相对为优,而农业效益低下;从东、中、西部地区的产业结构看,无论就业结构还是产值结构都与全国各省(市、区)产业结构的基本形式相一致,与发达的资本主义国家(美国、日本)相比差距明显,产业结构亟待升级.  相似文献   

Regionality in Norwegian farmland abandonment: Inferences from production data     

《Applied geography (Sevenoaks, England)》2014

Economic subsidies continue to be in focus as potentially important drivers of agricultural change. Their exact functioning as drivers in very complex systems are not all that well analysed or documented however, and their effect e.g. in terms of environmental output are currently being questioned. In the work reported here, we focus on how the regionality of the farming system may influence the potential effect of agricultural subsidies, also in terms of farmland abandonment. We do this through using multiple linear regressions (MLR) and geographically weighted regression (GWR) on the Norwegian database on agricultural production data, combined with farm location data. Our findings demonstrate how the outcome of certain support systems may differ between regions, and how a region may dominate national statistic. We conclude that as subsidies continue to be a key tool in achieving agricultural policy aims, we need a better understanding of how the subsidy systems work. To understand the impact of a change in subsidy it is necessary to consider the local context in which it operates, e.g. demographics, bio-physical resources and feasibility of land rental. Spatial data and techniques such as spatial MLR and GWR are increasingly accessible to policy makers and should be used to provide insight into the local impacts of current policy. However this understanding must also emphasize farmer motivation and decision making and these investigations must be regionally based.  相似文献