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561.
562.
面向海域管理的海洋资源资产负债表编制框架研究 总被引:2,自引:0,他引:2
编制海洋资源资产负债表是海洋生态文明建设的重要举措,然而目前对海洋资源资产负债表的研究相对薄弱,存在关键概念缺乏科学定义、核算方法可行性不足、报表体系设计不完善等问题。本文基于"生态管海、生态用海"的理念,针对现有问题探讨了海洋资源资产负债表编制框架:首先,根据自然资源资产负债表编制的目的和要求,界定了海洋资源资产负债表编制过程中的关键概念,并基于此,进一步考虑海洋资源属性、开发利用特点和当前海域管理重点任务确定了海洋资源资产的核算范围,包括海洋生物资源资产、海洋空间资源资产与海洋矿产资源资产;其次,针对不同海洋资源的特性,提出了具有较高可行性的海洋资源资产实物量和价值量核算方法;再次,根据不同海洋资源的价值特点,确认了资源过度耗减、环境破坏与生态损害三种负债形式并提出了相应的核算方法;最后,基于以上研究,形成了较为完善的海洋资源资产负债表报表体系,以期为海洋资源精细化管理和科学配置提供技术支撑。 相似文献
563.
本文通过对阿蒙森海西北部陆隆AMS01岩心沉积物颜色、粒度及地球化学等多种指标分析,重建了该地区氧同位素9期(MIS9,大约距今34万年)以来冰盖与古生产力演变历史,结果表明:(1)岩心沉积物粒度与古生产力替代指标表现出明显的冰期–间冰期旋回变化特征;(2)MIS9、MIS7和MIS5等间冰期沉积速率较小,沉积物呈褐色,冰筏碎屑含量低,生源组分含量高,反映出该时期阿蒙森海地区气候温暖,冰盖发生了大规模退缩,冰盖–冰架–冰山等陆源冰对沉积物的影响减弱,海冰覆盖减弱,有利于浮游植物的生长和繁殖;(3)MIS8c、MIS8a、MIS6、MIS2等冰期沉积速率大,沉积物呈灰色,沉积物随之变粗,冰筏碎屑含量高,生源组分含量低,说明该时期冰盖大幅扩张,陆隆区成为近冰盖/冰架沉积环境,海冰和冰山密集,海洋生产力显著降低;(4)冰期、间冰期内,冰盖与古生产力也有不同程度的波动;特别是MIS8b期发育浅褐色间冰阶沉积,冰筏碎屑含量低,生产力水平与间冰期基本持平,说明阿蒙森海地区冰盖、海洋对气候变化的响应比东南极地区敏感。 相似文献
564.
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566.
简要讨论了用于桩锚支护设计的自由端法与固定端法中存在的问题,提出了一种新的设计方法。新方法在计算土压力零点以下长度时采用力平衡而不是力矩平衡的方法,简化了计算,计算结果较趋近于安全、节省的目标。给出了详细计算过程与计算实例。 相似文献
567.
中国南极冰川学研究10 a回顾与展望 总被引:13,自引:7,他引:6
The study of Antarctic glaciology in China is reviewed with the emphasis on the past decade. Much progress has been achieved in the physical characteristics of the Antarctic ice sheet and caps and in the study of climatic and environmental records in Antarctic snow and ice. Through observations of snow profiles of numerous snow-pits and shallow cores in the Wilkes Land and Lambert Glacier basin and along the route of the 1990 International Trans-Antarctica Science Expedition (ITASE), the regional features of snow deposition and densification in Antarctica were revealed. The Nelson Island ice cap in South Shetland Islands was investigated in detail that greatly enriched the knowledge of glaciers under a sub-Antarctic maritime climate. From the analyses of shallow ice cores and surface snow samples, in particular those taken along the ITASE route, the systematic data of stable isotopes, soluble impurities and heavy metal Pb in present precipitation in Antarctica has been obtained. Some suggestions are proposed through discussing the present hot points in the above fields. 相似文献
568.
萍乐坳陷东段推覆构造特征及煤田预测 总被引:1,自引:0,他引:1
周宝直 《华东地质学院学报》2000,23(2):134-140
萍乐坳陷东段推覆构造可划分为三个逆冲构造带,不同地段推覆的结构 、性质、方向不同,形成了各具特色的推覆席体,对区内含煤岩系既有强裂的破坏作用,又有一定的掩埋保藏作用,利用推覆构造理论圈定出区内六个找矿靶区。 相似文献
569.
A system of multi-fluid MHD-equations is used to compare adiabatic and non-adiabatic transport of the energetic particles in the magnetospheric plasma sheet. A “slow-flow” approximation is considered to study large-scale transport of the anisotropic plasma consisting of energetic electrons and protons. Non-adiabatic transport of the energetic plasma is caused by scattering of the particles in the presence of both wave turbulence and arbitrary time-varying electric fields penetrating from the solar wind into the magnetosphere. The plasma components are devided into particle populations defined by their given initial effective values of the magnetic moment per particle. The spatial scales are also given to estimate the non-uniformity of the geomagnetic field along the chosen mean path of a particle. The latters are used to integrate approximately the system of MHD-equations along each of these paths. The behaviour of the magnetic moment mentioned above and of the parameter which characterizes the pitch-angle distribution of the particles are studied self-consistently in dependence on the intensity of non-adiabatic scattering of the particles. It is shown that, in the inner magnetosphere, this scattering influences the particles in the same manner as pitch-angle diffusion does. It reduces the pitch-angle anisotropy in the plasa. The state of the plasma may be unstable in the current sheet of the magnetotail. If the initial state of the plasma does not correspond to the equilibrium one, then, in this case, scattering influences the particles so as to remove the plasma further from the equilibrium state. The coefficient of the particle diffusion across the geomagnetic field lines is evaluated. This is done by employing the Langevin approach to take the stochastic electric forces acting on the energetic particles in the turbulent plasma into account. The behaviour of the energy density of electrostatic fluctuations in the magnetosphere is estimated. 相似文献
570.
This paper presents the spatial and temporal variations of sheet flow and sediment transport on an agricultural field under natural rainfall. The study site is located in western France (Rennes, Brittany) where rainfall amount and intensity are moderate. It is a field of garden-peas presenting a convex–concave gentle slope where only sheet flow is observed. A network of simple, low-cost collectors is used to measure sheet flow and sediment transport along the slope and to estimate the spatial variability for a given position on the slope. The water and sediment discharge was measured for each rainfall event from February to June. The analysis of space and time variations according to the characteristics of the rainfall events, changes in vegetation and soil crusting shows that the sheet flow is low and the runoff coefficient decreases as the slope length increases. Infiltration is particularly active in concave parts of the hillslope whatever the characteristics of the rainfall events. Sediment transport decreases in time as the soil crusts and vegetation develops. 相似文献