青藏高原地壳水平差异运动的GPS观测研究

青藏高原及其周边580多个GPS站点的观测资料为基础，通过消除青藏高原的整体刚性运动，将GPS水平速度场归化到“青藏高原整体固定”的参考框架下，使青藏高原内部不同区域的水平差异运动得以获得最大限度的突出。所得速度场图像显示：①以玛尼-玉树-鲜水河断裂为界的青藏高原东南部区域，最突出的内部水平形变表现为一条绕喜马拉雅东构造结的挤出式顺时针“流滑带”。而这一流滑带前缘速度场在青藏高原东南角呈现扇形发散特征，表明整个流滑带起因于高塑性上地壳物质在挤压和重力共同作用下的侧向逃逸；②介于玛尼-玉树-鲜水河断裂和海原断裂之间的青藏高原东北部区域，总体上表现出比较均匀的左旋剪切带特性，但这种左旋剪切在青藏高原东缘的龙门山一带已不再明显，且四川盆地及其以北区域，并未承受强烈挤压。因此，青藏高原东北部区域，相对于高原整体，并无明显的东向逃逸。③在整个青藏高原区域内，阿尔金断裂、海原断裂及玛尼-玉树-鲜水河断裂两侧的速度场显示了明显的差异，反映出这三条断裂带现今强烈的活动性。由于位于玛尼-玉树-鲜水河断裂和喀喇昆仑-嘉黎断裂之间的塑性流滑带的独立东向“逃逸”所产生的“拖拽”使流滑带以北区域表现为整体均匀的左旋剪切，而流滑带以南区域呈现了一定的右旋剪切。     

盐度对北极海冰细菌生长的影响

从中国第二次北极科学考察采集的海冰样品中分离到8种细菌,研究了盐度对其生长的影响。结果表明,8株海冰细菌对盐度有着广泛的适应性,在盐度为30-90的范围内均可较快生长,其中菌株BJ2、BJ3和BJ7的盐耐受性较强。进一步的研究表明,BJ2、BJ3和BJ7在0-150 的盐度范围内均有不同程度的生长,盐度为0-30时,菌株的生长最快;盐度为180时,这三株菌株也均有短暂的生长。随着盐度的增加,三株菌株生长的延迟期增加,到达生长稳定期的时间也相应增加。温度对菌株BJ2、BJ3和BJ7的盐耐受性也有着一定的影响,随着温度的升高, 菌株的生长速度变慢,但盐耐受性有所增加。     

The crust and upper mantle structure and the stretching mechanism of the Okinawa Trough

The major aim of this study is to put forwad a valid model to explain the gravity anomalies observed over the Okinawa Trough which the crustal structure and a reasonable model of the downgoing slab themselves cannot explain. The result of inversion indicates that the lithosphere above the center of the trough thins out to 45% of the normal thickness (63 km) of the lithosphere of the East China Sea. Fur ther, the originations of lithospheric force are discussed. The tensional stress of about 160 bar arising from density contrast in the Okinawa Trough is recognized to be the most important causative factor in the stretching of the trough. Contribution No. 1487 from Institute of Oceanology. Academia Sinica     

长江河口最大浑浊带研究

本文在以前一系列研究的基础上,把长江河口最大浑浊带视作一个系统,对它形成的环境背景、时空变化规律、泥沙来源、絮凝作用对悬沙落淤的影响、浮泥的特性与分布、悬沙的富集机制等进行了较系统的综合分析,并指出了需要深入研究的问题。     

Use of multi-point analysis and modelling to address cross-scale coupling in space plasmas: Lessons from Cluster

The properties of plasmas (in space) are fundamentally governed by both ‘cross-scale’ coupling and comparative temporal behaviour operating over the micro-, meso-, and (MHD-) fluid regimes: for example, under conditions of turbulence, during magnetic reconnection and in shocks and other plasma boundaries. These themes map to a number of related and overlapping, phenomena, where known phenomena play different roles in each theme. Detailed understanding of fundamental plasma processes therefore requires analysis of both theoretical models (to distinguish the collisionless from the collisional regimes) and multi-scale measurements (suitable to address issues of stationarity). In particular, the investigation of phenomena requires analysis techniques which can distinguish and quantify temporal behaviour and the multi-scale spatial behaviour. The analysis of existing, multi-point data sets has led to a number of data co-ordination methods, such as the four spacecraft analysis tools developed for cluster, and we consider examples here. Advanced analysis concepts may be investigated with suitable considerations of measurement quality:adequate sampling of phenomena (for example, to extract the necessary information on the mechanisms operating) requires suitable spacecraft configurations and directly relates to the measurement quality achievable. A particular issue is how to resolve temporal behaviour across the spatial regimes, so that the data set is suitably coordinated. With the addition of theoretical modelling (in the context of particular phenomena) both the space and laboratory plasma regimes may be compared and we give an example of nonlinear wave coupling across spatial scales in this context.     

Debris-flow of Zelongnong Ravine in Tibet

Zelongnong Ravine, a branch ravine of Brahmaputra, is an old large glacier debris-flow ravine. Debris-flows with medium and/or small scales occur almost every year; multiple super debris-flows have also broken out in history, and have caused destructive disaster to local residents at the mouth of ravine and blocked Brahmaputra. The huge altitude difference and the steep slope of the Zelongnong Ravine provide predominant energy conditions for the debris-flow. The drainage basin is located in the fast uplifted area, where the complicated geologic structure, the cracked rock, and the frequent earthquake make the rocks experience strong weathering, thus plenty of granular materials are available for the formation of debris-flows. Although this region is located in the rain shadow area, the precipitation is concentrated and most is with high intensity. Also, the strong glacier activity provides water source for debris-flow. According to literature reviews, most debris-flows in the ravine are induced by rainstorms, and their scales are relatively small. However, when the melted water is overlaid, the large scale debris-flows may occur. Parametric calculation such as the flow velocity and the runoff is conducted according to the monitoring data. The result shows that large debris-flows can be aroused when the rainstorm and the melted water are combined well, but the possibility of blocking off Brahmaputra is rare. The occurrence of the super debris-flows is closely related to the intense glacier activity (e.g., glacier surge). They often result in destructive disasters and are hard to be prevented and cured by engineering measures, due to the oversized scales. The hazard mitigation measures such as monitoring and prediction are proposed.     

Driving factors and spatiotemporal effects of environmental stress in urban agglomeration: Evidence from the Beijing–Tianjin–Hebei region of China

Environmental stress is used as an indicator of the overall pressure on regional environmental systems caused by the output of various pollutants as a result of human activities. Based on the pollutant emissions and socioeconomic databases of the counties in Beijing–Tianjin–Hebei region, this paper comprehensively calculates the environmental stress index(ESI) for the urban agglomeration using the entropy weight method(EWM) at the county scale and analyzes the spatiotemporal patterns and the differences among the four types of major functional zones(MFZ) for the period 2012–2016. In addition, the socioeconomic driving forces of environmental stress are quantitatively estimated using the geographically weighted regression(GWR) method based on the STIRPAT model framework. The results show that:(1) The level of environmental stress in the Beijing–Tianjin–Hebei region was significantly alleviated during that time period, with a decrease in ESI of 54.68% by 2016. This decrease was most significant in Beijing, Tangshan, Tianjin, Shijiazhuang, and other central urban areas, as well as the Binhai New Area. The level of environmental stress in counties decreased gradually from the central urban areas to the suburban areas, and the high-level stress counties were eliminated by 2016.(2) The spatial spillover effect of environmental stress increased further at the county scale from 2012 to 2016, and spatial locking and path dependence emerged in the cities of Tangshan and Tianjin.(3) Urbanized zones(development-optimized and development-prioritized zones) were the major areas bearing environmental pollution in the Beijing–Tianjin–Hebei region in that time period. The ESI accounted for 65.98% of the whole region, where there was a need to focus on the prevention and control of environmental pollution.(4) The driving factors of environmental stress at the county scale included population size and the level of economic development. In addition, the technical capacity of environmental waste disposal, the intensity of agricultural production input, the intensity of territorial development, and the level of urbanization also had a certain degree of influence.(5) There was spatial heterogeneity in the effects of the various driving factors on the level of environmental stress. Thus, it was necessary to adopt differentiated environmental governance and reduction countermeasures in respect of emission sources, according to the intensity and spatiotemporal differences in the driving forces in order to improve the accuracy and adaptability of environmental collaborative control in the Beijing–Tianjin–Hebei region.     

南非交通基础设施建设的潜力与方向评估

交通基础设施作为经济发展的“先行官”,对国民经济发展具有巨大推动作用。参与南非重大基础设施建设,对加强中国与南非战略合作、推动中国企业走入南非投资兴业具有重要意义。2010年,南非《全国运输总体规划(2005-2050)》（即 NATMAP 2050）正式出台,对南非铁路、公路、航空、港口、管道等基础设施进行了详实的安排,总投资额高达7500亿兰特。本文通过深入解读该规划,识别出南非铁路、港口等交通基础设施领域的投资重点和重大项目。在此基础上,结合南非城镇体系分布、矿产资源开发、国际贸易发展等方面的现状特征分析,系统评价了南非高铁客运通道、大宗货运通道、港口体系的投资潜力和方向,筛选出投资潜力较大的关键项目,以期为我国更好地参与南非经济发展进程提供决策支持,同时也为我国企业到南非投资创业提供参考。     

On the dynamics of a solitary vortex

The dynamic equilibrium of a solitary vortex of permanent form but arbitrary shape is investigated on a β plane. The vortex is assumed to propagate in the east-west direction. Forces and moments acting on the vortex are computed and the balances between them obtained. The dynamic balances are required for the equilibrium of the vortex and represent the conditions necessary for the existence of a solitary vortex of permanent form. These conditions have two useful expressions, one as integral constraints on the vortex structure and the other as formulas for the propagation speed of the vortex. For the latter, the speed is shown to be proportional to the averaged velocity moment of the vortex and inversely proportional to its averaged relative vorticity. The propagation speed also depends on the size of the vortex; it increases with size for westward propagation and decreases with size for eastward propagation. The effect of current shear on the vortex is also investigated. The results of this study are applicable to the nonlinear barotropic vortex in a nondivergent fluid as well as to the baroclinic vortex, provided that the latter satisfies the quasigeostrophic approximation.     

甬江河床演变及航道治理

本文分析甬江动力、泥沙、边界及河床演变的基本特征,提出甬江航道整治的原则和措施。