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Jingyi Cong Gang Hu Tara N. Jonell Zhongpeng Yuan Xianghuai Kong Yong Zhang Yonghong Wang 《中国海洋大学学报(英文版)》2020,19(4):790-800
Large amounts of sediments originating from the Changjiang(Yangtze) River are deposited in the subaqueous delta and in the adjacent muddy area off the mouth and on the inner shelf of the East China Sea. The terrestrial sediments deposited in these areas not only contain information about the composition and environment of the source area, but they also record changes in anthropogenic activities. A sediment piston core(CJ0702) was extracted from the Changjiang subaqueous depocenter(31.00°N, 122.67°E) in a water depth of 22.0 m. The core was subsampled at 1 – 2 cm intervals and analyzed for grain size, clay mineralogy, and major element geochemistry. Results indicate a relatively high sediment accumulation rate of approximately 3.11 cm yr~(-1). These parameters exhibited only minor cyclical fluctuations in the core, which resulted from many factors. During the past 120 years, the Changjiang River-derived sediment is the primary source of sediment in the offshore mud area without evidence for the Yellow River-derived sediment increasing. After the trunk stream shifted from the North Branch to South Branch, the variations of proxies are controlled by the periodic fluctuation possibly linked to El Ni?o-Southern Oscillation(ENSO) and the Pacific Decadal Oscillation(PDO). In addition, anthropogenic heavy metal concentrations can be divided into three stages, which coincide well with economic development and environmental protection policies. 相似文献
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介绍了基于GIS的分布式通信资源管理系统的设计与实现思路。提出了以GIS为基础平台.以地图为载体,整合各种通信资源,建立通信资源综合空间数据库的方法,并探讨了跨区域通信资源的分布式管理模式和系统实现方法。 相似文献
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长江三峡库区崩滑地质灾害与防治 总被引:3,自引:0,他引:3
长江三峡工程坝址位于湖北省宜昌 县三斗坪,设计大坝坝顶高程185米, 正常蓄水位175米。水库涉及湖北省和 重庆市20个县〔区、市)。库区长江干流 库段从大坝所在地三斗坪到上游库尾所 在地重庆市巴南区大塘坝,全长574公 里;主要支流有50余条。水库干支流库 岸岸线总长达5,300公里。 三峡大坝坝址在着名的黄陵背斜核 部,工程地质条件良好,基岩是前震旦 纪花岗岩(黑云母石英闪长岩),岩体坚硬完整。水库区则是我国崩滑地质灾害多发区,这里的自然与地质环境易于诱发崩滑地质灾害,因此崩滑地质… 相似文献
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Phytoplankton assemblage of Yangtze River Estuary and the adjacent east China sea in summer, 2004 总被引:6,自引:0,他引:6
A cruise was conducted from late August to early September 2004 with the intention of obtaining an interdisciplinary understanding of the Yangtze River Estuary including the biological, chemical and physical subjects. Water sample analysis indicated that total phytoplankton species richness was 137. Of them 81 were found in Bacillariophyta and 48 in Pyrrophyta, accounting for 59.1% and 35.0% respectively. The average cell abundance of surface water samples was 8.8×104 cells L-1, with the maximum, 102.9×104 cells L-1, encountered in the area (31.75°N, 122.33°E) and the minimum, 0.2×104 cells L-1, in (30.75°N, 122.17°E). The dominant species at most stations were Skeletonema costatum and Proboscia alata f. gracillima with the dominance of 0.35 and 0.27. Vertical distribution analysis indicated that obvious stratification of cell abundance and dominant species was found in the representative stations of 5, 18 and 33. Shannon-Wiener index and evenness of phytoplankton assemblage presented negative correlation with the cell abundance, with the optimum appearing in (30.75°N, 122.67°E). According to the PCA analysis of the environmental variables, elevated nutrients of nitrate, silicate and phosphate through river discharge were mainly responsible for the phytoplankton bloom in this area. 相似文献
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Offshore Fault Geometrics in the Pearl River Estuary,Southeastern China: Evidence from Seismic Reflection Data 总被引:1,自引:0,他引:1
Jinghe Cao Shaohong Xia Jinlong Sun Fang Zhao Kuiyuan Wan Huilong Xu 《中国海洋大学学报(英文版)》2018,17(4):799-810
The Pearl River Estuary (PRE) is located at the onshore-offshore transition zone between South China and South China Sea Basin, and it is of great significant value in discussing tectonic relationships between South China block and South China Sea block and seismic activities along the offshore active faults in PRE. However, the researches on geometric characteristics of offshore faults in this area are extremely lacking. To investigate the offshore fault distribution and their geometric features in the PRE in greater detail, we acquired thirteen seismic reflection profiles in 2015. Combining the analysis of the seismic reflection and free-air gravity anomaly data, this paper revealed the location, continuity, and geometry of the littoral fault zone and other offshore faults in PRE. The littoral fault zone is composed of the major Dangan Islands fault and several parallel, high-angle, normal faults, which mainly trend northeast to northeast-to-east and dip to the southeast with large displacements. The fault zone is divided into three different segments by the northwest-trending faults. Moreover, the basement depth around Dangan Islands is very shallow, while it suddenly increases along the islands westward and southward. These has resulted in the islands and neighboring areas becoming the places where the stress accumulates easily. The seismogenic pattern of this area is closely related to the comprehensive effect of intersecting faults together with the low velocity layer. 相似文献
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Pang Yue Fan Dejiang Sun Xiaoxia Sun Xueshi Liu Ming Yang Zuosheng 《中国海洋大学学报(英文版)》2020,19(4):801-810
For a long time, most studies about pyrite have focused on sediments while only a few have focused on pyrite in water. In this study, a method that combines the scanning electron microscopy(SEM) and the energy dispersive X-ray spectrometry(EDS) was used to compare pyrite particles suspended in water to those in associated bottom sediments, both obtained from the mixing zone of the Yangtze Estuary. It was found that the pyrite particles in the two media have similar morphologies and size distributions. The particle morphology mainly includes two types, single crystal and aggregate, and the particle size mainly ranges from 0.5 to 2 μm. The pyrite particles in water exhibit an increase in relative content towards the sea, and their transport and deposit processes are mainly affected by hydrodynamic conditions. It is concluded that the pyrite particles in the suspended matter mainly derived from the resuspension of sediments, which are products of the early diagenesis. Precursor minerals may appear during the formation of pyrite, but are generally restricted by the diagenetic environment and local microenvironment. 相似文献
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A field observation was carried out in the Changjiang (Yangtze) River Estuary from May 19 to 26, 2003. A total of 29 stations, including 2 anchored stations, were occupied through almost the whole salinity gradient. Based on the observation data, biogeochemistry of chemical oxygen demand (COD) was examined. Spatial distribution pattern of COD shows that it decreased downstream. The COD concentration varied generally within a narrow range of 1.24-1.60 mg/L in the zone around the river mouth, beyond which it decreased rapidly to 0.20 mg/L. In the mixed water zone, the fluctuation in COD was smaller at 2 m above the bottom layer than at the surface layer in 48 h. In the seawater zone, the 48-h fluctuation at the surface was the largest, followed by that of 5 m below the surface and 2 m above the bottom layers in a range of from 2.50 to 0.55 mg/L. Freshwater discharge was the dominant source of COD in the estuary. The average COD beyond the river mouth was 2.7 mg/L, which accorded with the Chinese seawater quality Grade I. Relationships between dissolved oxygen and biogeochemical parameters such as suspended particulate matter, dissolved organic matter and chlorophyll-a were also discussed. 相似文献
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The distributions and relationships of O_2, CO_2, and dimethylsulfide (DMS) in the Changjiang (Yangtze) Estuary and its adjacent waters were investigated in June 2014. In surface water, mean O_2 saturation level, partial pressure of CO_2 (pCO_2), and DMS concentrations (and ranges) were 110% (89%–167%), 374μatm (91–640 μatm), and 8.53 nmol L~(-1) (1.10–27.50 nmol L~(-1)), respectively. The sea-to-air fluxes (and ranges) of DMS and CO_2 were 8.24 μmol m~(-2)d~(-1) (0.26–62.77 μmol m~(-2)d~(-1)), and -4.7 mmol m~(-2)d~(-1) (-110.8-31.7 mmol m~(-2)d~(-1)), respectively. Dissolved O_2 was oversaturated, DMS concentrations were relatively high, and this region served as a sink of atmospheric CO_2. The pCO_2 was significantly and negatively correlated with the O_2 saturation level, while the DMS concentration showed different positive relationships with the O_2 saturation level in different water masses. In vertical profiles, a hypoxic zone existed below 20 m at a longitude of 123?E. The stratification of temperature and salinity caused by the Taiwan Warm Current suppressed seawater exchange between upper and lower layers, resulting in the formation of a hypoxic zone. Oxidative de-composition of organic detritus carried by the Changjiang River Diluted Water (CRDW) consumed abundant O_2 and produced additional CO_2. The DMS concentrations decreased because of low phytoplankton biomass in the hypoxic zone. Strong correlations ap-peared between the O_2 saturation level, pCO_2 and DMS concentrations in vertical profiles. Our results strongly suggested that CRDW played an important role in the distributions and relationships of O_2, CO_2, and DMS. 相似文献
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ENG Mohammed Al Zubairi 《东北亚地学研究》2001,(2)
1 IntroductionTheRedSeaisanarrowinlandsea ,separatingtheArabianPeninsula,WAsia,fromNEAfrica .ItextendsNWfromthestraitofBabAlMandab ( 相似文献
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《广东海洋大学学报》2014,(1)
应用计算机专家系统对红树林湿地的鸟类进行分类与鉴别。结合产生式系统体系结构,设计开发红树林湿地鸟类鉴别系统,该系统利用鸟类目科检索表与二叉树的结构相似性,构建鸟类目科检索二叉树,结合B+树和判定树学习,设计鸟类检索编码表,实现红树林湿地鸟类目科和属种的鉴别。 相似文献
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ENG Mohammed Al Zubairi 《世界地质(英文版)》2001,4(2)
The Red Sea is a pericratonic upper Tertiary basin which developed on the continental margin of Arabia. It is characterized by halokinetic tectonics in the upper structural stage and block- Rifting in the lower structural stage. This margin is overprinted on a Pre - rift Mesozoic platform. Hydrocarbon exploration interest in the Yemeni Red Sea sector and Offshore area (Tihama Basin) is based on three objectives, which cross pond to stages in geotectonic evolution; Mesozoic Pre - rift targets; Miocene Syn- Rift Salt targets; and upper Miocene- Pliocene Post - rift drift sequences. Reservoirs with appropriate sealing units ( salt or shale ) have been recorded. Models of source rock maturation using observed geothermal gradients are consistent with analytical results, and prove of oil and gas generation. Most traps are described as faulted, fault - blocks, listric - faults or structural. The evaporite group mainly consists of Halite and Anhydrite, that exhibits a strong halokinesis affecting a structural style- of Infra and Intra evaporite sequences in offshore (Tihama basin ). 相似文献
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针对当前地名地址数据采集规范不统一、采集效率低、采集效果不理想、数据质量低等问题,该文探索了一种基于移动GIS技术的地名地址数据采集和更新方法,设计了以任务为核心的数据下发和下载、采集和更新、内业核查和数据质检等内容的内外业一体化流程,建立了以道路为基准的数据采集和更新模式,通过位置比对、影像分析、照片匹配、实地核查等技术建立了多维度、多层次的数据质检方式,基于"天地图·山东"地图API开发了地名地址采集系统,实现了地名地址数据的快速采集和更新,有效提高了地名地址数据采集的效率和质量,推进了"天地图·山东"省市县数据一体化和联动更新工作。 相似文献