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1.
深水重力流沉积研究经历了半个多世纪发展,从浊流及鲍马序列开始,到把深水砂岩普遍解释为浊流成因以及海底扇模式的建立,再到今天学者们对鲍马序列的质疑,深水重力流沉积的研究经历了认识上的螺旋式上升旋回。目前关于深水重力流沉积争议的焦点在于高密度浊流是否属于浊流的范畴,深水砂岩是否都是浊流成因。以Shanmugam为代表的学者认为,绝大多数的深水砂岩都是碎屑流成因而非浊流成因,并且提出了重力流分类新方案,同时建立了与其匹配的深水斜坡沉积模式。通过对前人成果的广泛调研,经过对比总结,认为:①根据流变学和沉积物搬运机制,重力流分为碎屑流(砂质碎屑流和泥质碎屑流)、颗粒流、浊流;②浊流的韵律结构特征为明显的正粒序且没有漂浮的碎屑颗粒,碎屑流自下而上呈逆-正粒序的两套韵律变化且发育有漂浮的碎屑颗粒;③Walker的综合扇模式与Shanmugam的斜坡沉积模式,二者是可以共存的,只是在某一地区适用性不同而已。   相似文献   

2.
黄河入海口水域春季浮游动物群落特征研究   总被引:3,自引:0,他引:3  
对2008、2009年黄河入海口水域春季浮游动物进行调查,采用香农-威纳多样性指数(Shannon-Weiner index)、Pielou均匀度指数和McNaugton优势度指数对其浮游动物群落特征进行分析。结果表明:浮游动物鉴定出6大类44种,以甲壳动物种类最多;2008年5月黄河入海口水域浮游动物多样性指数范围为0.92~2.65,均匀度变化范围为0.25~0.66;2009年5月浮游动物多样性指数范围为0.76~2.87,均匀度变化范围为0.21~0.70。黄河入海口水域浮游动物时空分布较不均匀,群落特征(包括丰度、多样性指数、均匀度和优势度等)在同一时期同一水域各采样点间差异较大,同一采样点不同年份差异显著。  相似文献   

3.
Forests and the dynamic changes play decisive roles in soil erosion prevention, biodiversity conservation and climate warming mitigation, and are crucial for China to achieve carbon neutrality because of the ability for carbon uptake. China’s forests experienced a substantial change over the past century, primarily since the forest conservation and restoration programs were implemented. In this paper, the progress of China’s forest change and the similarities and differences of the spatio-tempor...  相似文献   

4.
Evaporation duct is an ubiquitous natural phenomenon over the ocean and can be diagnosed by evaporation duct model. The model proposed by Paulus and Jeske and another model established by the American naval postgraduate school are the most widely used. They are called PJ model and NPS model, respectively. Two methods are used to investigate the global sensitivity of PJ model and NPS model in China Seas. The first method is based on meteorological and oceanographic observation data in China Seas. Considering the system random error caused by sensor measurement inaccuracies, the mean relative error and mean absolute error are used as criterion for sensitivity analysis. The second method, called Extended Fourier Amplitude Sensitivity Test(EFAST), takes into account the interaction between input parameters and is used for sensitivity analysis. The results show that NPS model is more sensitive to the random errors of sensors than PJ model. The mean relative errors of PJ model and NPS model are 11.43% and 14.81%, respectively. The results of global sensitivity parameter analysis indicate that wind speed is the key factor of PJ model, while all input parameter of NPS model have relatively large total sensitivity index. In addition, sensitivity analysis results confirm that wind speed is one of main driving factors for the formation of evaporation duct. These results are valuable for the selection of diagnosis models for evaporation duct, the evaluation of radio wave propagation in the marine atmospheric surface layer, and the prediction technique of evaporation duct based on numerical weather prediction(NWP) in China seas.  相似文献   

5.
The paper presents a numerical two-dimensional model (with a realistic sea basin and wind fields as exter nal forcing) to simulate the basic features of the wintertime circulation in the Bohai and Huanghai (Yellow) Seas (BHS) and to show how the circulation can be driven by wind. The main results can be summarized as follows (1) The basic features of the BHS wintertime circulation can be depicted by the wind-driven barotropi'c motion. (2) The traditionally named Huanghai Sea Warm Current (HSWC) is actually generated by the north wind field, at least in winter. (3) The southward coastal current off the Korean west coast plays a more significant role in the southern Huanghai Sea wintertime circulation than traditionally believed. (4) Though the coastal landform and bottom topography play important roles in the wintertime BHS circulation pattern, the wind is a primary forcing.  相似文献   

6.
山东诸城地区是闻名世界的恐龙化石宝库,这里不仅保存有数量巨大的晚白垩世恐龙骨骼化石,还发现有数量众多的早白垩世恐龙足迹化石。到目前为止,诸城境内共发现的恐龙足迹化石点有3处,分别为南部的皇龙沟与北部的张祝河湾和棠棣戈庄。根据前人对这3处恐龙足迹化石点的研究,对其发现和研究历史、足迹类型(包括非恐龙足迹)、不同类型足迹的大小和特征,以及古地理和古气候等进行了总结,提出了诸城恐龙足迹化石研究中亟待解决的问题。  相似文献   

7.
采用后殖民主义理论,从多元文化主义角度分析论述《午夜的孩子》对印度民族道路的探讨:小说中东西方叙事模式的混合以及印度方言和标准英语的融合是对西方权力话语的解构;通过比较作为多元文化存在的午夜的孩子大会和英迪拉领导的独裁政府,重构多元文化主义而非激进民族主义,是应对权力话语的后殖民话语;小说中人物的混杂性,进一步强调东方和西方的相互依存性,印度民族道路有赖于尊重文化差异,让不同的文化相互碰撞、融合并共存。  相似文献   

8.
Circulation in China Seas has been investigated by Chinese oceanographers in some detail for many years. However, owing to data being sparse and scarce, studies were basically concerned in interseasonal (mainly summer and winter) fluctuations and almost none was in the interannual variability of the circulation in China Seas. It is pointed out that the routine (monthly or bimonthly) hydrographical section data on the continental shelf of China Seas accumulated since 1975, can be used to examine the interannual variability of the shelf circulation. An example is given to show there is interannual variability of shelf circulation in the East China Sea. And what is more, a hypothesis is proposed to describe where the interannual variability comes from and to explain why it is strongly correlated with El Niño events. It is strongly suggested that the interannual variability of the shelf circulation in China Seas be studied, as a strategy, with the routine hydrographical survey, which should be seriously continued, combined with cooperative study in the Philippine Sea and the western tropical Pacific Ocean.  相似文献   

9.
A 3.8-kin Coupled Ice-Ocean Model (C1OM) was implemented to successfully reproduce many observed phenomena in the Beaufort and Chukchi seas, including the Bering-inflow-originated coastal current that splits into three branches: Alaska Coastal Water (ACW) , Central Channel, and Herald Valley branches. Other modeled phenomena include the Beaufort Slope Current (BSC) , the Beaufort Gyre, the East Siberian Current ( ESC), mesoscale eddies, seasonal landfast ice, sea ice ridging, shear, and deformation. Many of these downscaling processes can only be captured by using a high-resolution CIOM, nested in a global climate model. The seasonal cycles for sea ice concentration, thickness, velocity, and other variables are well reproduced with Solid validation by satellite measurements. The seasonal cycles for upper ocean dynamics and thermodynamics are also well reproduced, which include the formation of the cold saline layer due to the injection of salt during sea ice formation, the BSC, and the subsurface upwelling in winter that brings up warm, even more saline Atlantic Water along the shelfbreak and shelf along the Beaufort coast.  相似文献   

10.
Tourism industry has become an important part of Indian economy, and tourism development has been, however, concentrated to a few areas. Accumulation of tourism activities has reached the critical stage in most of the tourism centers, which pose serious threats to the natural environment. The Bhyundar Valley of Nanda Devi Biosphere Reserve (NDBR) in Uttarakhand State of the Indian Himalaya is a burning example of such problems. Land use/cover changes, deforestation and accumulation of garbage are some of the negative impacts of unregulated tourism in the valley. Unsustainable activities of tourists and villagers in the valley make such problems very severe. To deal with the ongoing problems and ensure community involvement in tourism management and environmental conservation, the Biosphere Reserve Authority introduced ecotourism in the form of Eco Development Committees (EDCs) in the Bhyundar Valley. Study reveals that many problems associated with tourism have been minimized to some extent with the help of EDCs but few are still prevailing in valley. However, the existing attempts to conserve the valley from the negative effects of tourism are inadequate and modifications are needed in the current initiatives.  相似文献   

11.
轨迹数据挖掘城市应用研究综述   总被引:1,自引:0,他引:1  
轨迹数据作为泛在地理信息环境中社会遥感数据的主要表现形式之一,为从个体的视角研究群体的空间移动规律,提供了新的数据支撑和研究思路。特别是在当前的大数据背景下,通过轨迹数据发掘人类的移动规律和活动模式,进而探求蕴含的深层次知识,是解决城市问题的重要途径,轨迹数据挖掘也由此成为地理信息科学及相关学科的研究热点。本文首先阐述了人类移动规律研究常用的轨迹数据集及在该数据集上开展的相关研究和典型应用;然后从城市空间结构功能单元的识别及城市韵律分析、人类活动模式的发现与空间移动行为预测、智能交通的时间估算与异常探测、城市计算的其他4个方面,综述了轨迹数据挖掘在城市中的应用;最后,指出了轨迹数据挖掘面临的挑战和进一步的发展方向。  相似文献   

12.
Platycephalus in Chinese sea area has a high commercial value.However,there were mis-identifications in previous records.In this study,we fully distinguished and diagnosed all five species,Platycephalus indicus,P.cultellatus,Platycephalus sp.,Platycephalus sp.1 and Platycephalus sp.2.The results revealed that P.cultellatus was overlooked by previous ichthyologists.Platycephalus sp.1 was misidentified as P.indicus in reality,and Platycephalus sp.2 only existed in the seas of Japan.Furthermore,morphological,especially phylogenetic analysis indicated that Platycephalus sp.from South China Sea differs from all former known species,which might be a new species.We identified all Platycephalus species in China seas for the first time,which will contribute to local species identification,biodiversity conservation and sustainable exploitation of Platycephalus species.  相似文献   

13.
Zooplankton was major indicator species of the environment. To explore the effect of marine environment on zooplankton distribution in the coast of China, the zooplankton samples from stations in Guanhe Estuary(GE), Changjiang(Yangtze River) Estuary(CE), Oujiang Estuary(OE), Jiulongjiang Estuary(JE) and Beilun Estuary(BE)(covering 14 latitudes) in spring were surveyed and the variation of zooplankton ecological group was researched. According to the adaptability temperature, the zooplankton was divided into two ecological groups: warm-temperate species and subtropical species. The warm-temperate species was the main dominant species and subtropical species was only dominant species in BE. Calanus sinicus, a warm-temperate species, was the only dominant species in all five estuaries. From north to south, the proportion of warm-temperate species in the five estuaries gradually decreased depends on the number, were 83.33%, 48.39%, 45.00%, 43.75% and 30.43%, respectively. In contrary, the proportion of subtropical species was gradually increased. The warm-temperate species predominated over the total abundance and the percentage was whopping high in the north estuaries, including GE(96.16%), CE(95.57%), OE(97.83%) and JE(95.53%). The abundance percentage of subtropical species have remarkably higher(82.39%) in BE. Five estuaries zooplankton community was subdivided into three zooplankton groups, which were the northern warm temperate zooplankton group, the southern subtropical zooplankton group and the estuarine brackish-water group. The water temperature and coastal current of China Sea are recognized as the main factors determining the distribution and community structure of estuarine zooplankton in spring.  相似文献   

14.
Li  Kaizhi  Ke  Zhixin  Tan  Yehui 《中国海洋湖沼学报》2018,36(5):1671-1680
Journal of Oceanology and Limnology - Relatively few studies have investigated the community structure of zooplankton in the atolls of the central South China Sea. Zooplankton were sampled at nine...  相似文献   

15.
Dam removal has been increasingly reported globally and is becoming an important approach for river management, restoration and environmental conservation in damming rivers. However, current limited knowledge of global trends in dam removal and related research may be potentially biased in terms of the geographic distribution and organisms studied. Such bias could mislead dam removal planning and management in different areas and ecological conservation for different taxa. In this study, we quantitatively and qualitatively analyzed datasets of dam removal and publications of dam removal research using bibliometric methods. A total of 1449 dam removal documents were published from 1953 to 2016. Trends, current hotspots and future directions of dam removal research were identified. The results from this study reveal that dam removal largely occurred in the North America and Europe, and most of the removed dams were small and old dams. With respect to the topic analysis, more dam removal studies should focus on the responses of a wide range of organisms, not only fish, as well as the interspecies relationships, food webs and ecosystem structures and functions. Based on our findings, we also provide some suggestions for future dam removal planning and analysis.  相似文献   

16.
17.
从经济创新发展能力、海洋经济创新发展能力和海洋经济创新发展能力分析技术等3个视角总结梳理近年来海洋经济创新发展的研究趋势以及不足。通过对文献的梳理与研究可知,未来对海洋经济创新发展能力的研究应该摆脱单一维度,形成多视角的研究;需要将定量分析和定性分析有机结合,才能使研究成果更具有说服力。  相似文献   

18.
19.
A new muricid gastropod species,L ataxiena lutescena sp. nov.,is described and illustrated. The new species was recognized during reidentification of the Muricidae collection in the Marine Biological Museum,Chinese Academy of Sciences,Qingdao. The specimens of the new species were collected from the East and South China Seas off Fujian,Guangdong,and Hainan Provinces. Lataxiena lutescena sp. nov. is similar to Lataxiena blosvillei(Deshayes,1832) in general shape,but can be distinguished from the latter by the shell sculpture and radular characteristics. Lataxiena lutescena sp. nov. also resembles Lataxiena bombayana(Melvill,1893),but differs from that species in the shell shape and anal notches and in lacking short spines on the shell.  相似文献   

20.
DNA barcoding provides accurate identification of zooplankton species through all life stages. Single-gene-targeted metagenomic analysis based on DNA barcode databases can facilitate longterm monitoring of zooplankton communities. With the help of the available zooplankton databases, the zooplankton community of the Changjiang (Yangtze) River estuary was studied using a single-gene-targeted metagenomic method to estimate the species richness of this community. A total of 856 mitochondrial cytochrome oxidase subunit 1 (cox1) gene sequences were determined. The environmental barcodes were clustered into 70 molecular operational taxonomic units (MOTUs). Forty-two MOTUs matched barcoded marine organisms with more than 90% similarity and were assigned to either the species (similarity>96%) or genus level (similarity<96%). Sibling species could also be distinguished. Many species that were overlooked by morphological methods were identified by molecular methods, especially gelatinous zooplankton and merozooplankton that were likely sampled at different life history phases. Zooplankton community structures differed significantly among all of the samples. The MOTU spatial distributions were influenced by the ecological habits of the corresponding species. In conclusion, single-gene-targeted metagenomic analysis is a useful tool for zooplankton studies, with which specimens from all life history stages can be identified quickly and effectively with a comprehensive database.  相似文献   

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