长江生源要素的输出通量   总被引：6，自引：2，他引：6  

沈志良  古堂秀  谢肖勃 《海洋科学》1991,15(6):67-69

长江是太平洋西岸最大的河流,它源源不断地向东海输送大量物质,是舟山渔场的重要化学物质基础,不仅对长江口海区以至整个东海有举足轻重的影响,对太平洋的影响也是不可忽视的。本文报道颗粒有机碳(POC)、溶  相似文献   

Evolution of the Axial Geometry of the Southwest Indian Ocean Ridge between the Melville Fracture Zone and the Indian Ocean Triple Junction – Implications for Segmentation on Very Slow-Spreading Ridges     

Parson  Lindsay  Sauter  Daniel  Mendel  Véronique  Patriat  Philippe  Searle  Roger 《Marine Geophysical Researches》1997,19(6):535-552

Geophysical data from 900 km of the Southwest Indian Ridge are used todescribe the pattern of evolution of the plate boundary between 61° Eand 70° E over the past 20 million years. The SWIR is anobliquely-opening, ultra slow-spreading axis, and east of61° E comprises a series of ridge sections, each about 100–120 kmin length. The orientation of these sections varies fromsub-orthogonal to oblique to the approximately N–S spreadingdirection. In general, the suborthogonal sections are shallower, commonlysubdivided into an array of discrete axial segments, and carry recognisablecentral magnetic anomalies. The majority of the oblique sections are single,continuous rifts without continuous axial magnetic signatures.Morphotectonics of the Southwest Indian Ridge crust have not previously beenwell constrained off-axis, and we here present sidescan sonar andswath bathymetric data up to 100 km from the ridge to demonstrate the complexities of its spatial and temporal evolution.A model is proposed that the segmentation style correlates with analong-axis variation between: (a) relatively thick crustal sections which overlie mantle sections with higher magmatic supply created in orthogonally-spreading segments and (b) those oblique sections associated with cooler, magmatically-starved mantle and thinner crust. These latter sections are formed at broad offset zones in theplate boundary, more precisely defined on faster-spreading ridges asnontransform discontinuities. The nonsystematic pattern of crustalconstruction, extensional basin formation and the absence of extension-parallel traces of discontinuities off-axis suggest that the oblique spreading sections are not fixed in space or time.  相似文献   

Static Analysis of Collision Strength of Offshore Platform     

Li Runpei Chen Weigang Gu Yongning Professor  Shanghai Jiao Tong University  Shanghai Assistant  Shanghai Jiao Tong University  Shanghai 《中国海洋工程》1996,(1)

In this paper a numerical analysis method combining FEM incemental technique with limit analysis concept is proposed for the study of the static strength of offshore platform in collision. Large deformation and plasticity are accounted for and the limit yield surface expressed by generalized stress for a tubular section is derived. The modified stiffness matrix of space beam element is formulated by Plastic Node Method. The buckling behavior of beam columns can also be taken into account. It can trace the generation of plastic hinges during loading and finally the ultimate strength of offshore platform against collision is obtained.  相似文献   

东海陆架区 Brunt-Väisälä 频率空－时变化分析     

顾传宬  蓝淑芳  傅秉照 《海洋科学集刊》1985,(25):1-10

Phillips (1966)指出，Brunt-V?is?l? 频率的分布是海洋中最重要的动力学特征之一。它是研究海水内部运动的一个重要参数，特别是关于海洋内波的研究。Brunt-V?is?l? 频率又称静态稳定性频率，更确切地应称作浮力频率，因为它与分层流体中作绝热移动的流体元的浮力变化相联系。Brunt-V?is?l? 频率(以下缩写成B. V. f.) 记作N。 根据B. V. f. 分布特征研究海水结构及动力学特性的论述颇多，但绝大多数侧重于深海大洋的研究，且时常将其上层撇开，从而可求得一个比较简单的解析式，这显然是由于海洋上层较其下层复杂的缘故。对于浅海陆架的情形，研究得比较少。前田明夫(1974)曾根据日本近岸(5公里以内)三个观测站上1-3天的观测资料，分析研究了日本近海上层海洋短周期海水温度起伏的动力学特性。本文试图对我国东海陆架浅海B.V.f.的空间分布和时间变化特征作一探讨。  相似文献   

渤海湾海河口区耗氧有机物的分布特征     

古堂秀  戴敏英  徐贤义  周陈年 《海洋科学集刊》1988,(29):65-76

渤海湾海河口区是北京、天津二大城市工业及生活污水排放入海处，是一比较典型的海域。1972年以来曾对渤海湾进行过综合性的环境污染调查和研究，但由于受调查范围和项目的限制，对河口区特别是大沽口、北塘口区有机污染物的迁移转化研究甚少，尚不足以就有机污染对河口生态环境的潜在影响作出科学判断。目前，有机污染已成为海河口区特别是其附近大城市的主要污染问题之一。本文以化学耗氧量(COD)、生物耗氧量(BOD5)、溶解氧(DO)等项目作为耗氧有机物污染程度评价的主要指标(还有氮、磷、本集另有专文讨论)，对海河口区有机污染物的迁移、转化及生态效应进行了调查研究，为有机污染评价提供数据并作初步探讨。  相似文献   

舟山马岙峡道的水文泥沙特性和峡道效应   总被引：6，自引：2，他引：6  

蒋国俊  金如义  顾建明  沈炳舫 《海洋通报》2001,20(1):15-22

根据舟山本岛北部马岙峡道实测水文泥沙资料和沉积物采样分析结果以及对马岙岸段岸滩的现场踏勘结果，分析了马岙峡道的水文泥沙特性及其峡道效应。文章认为，受峡道地形限制，马岙岸段水流呈现显著的往复流特性，潮流流速较强，水体含沙量较低，泥沙淤积较弱，岸滩处于冲淤平衡状态；受峡道内涨落潮流分流和汇流的共同作用，马岙小泥糊礁附近发育水下沙嘴，该沙嘴是以落潮流作用为主形成的浅滩，受涨潮流改造而形成的，并将在涨落潮流作用下逐渐增长，形成连岛沙嘴，使小泥糊礁附近岸线发展成弧形岸线，并达成新的平衡。  相似文献   

X₆₀钢在CO₂饱和盐水中缓蚀作用的研究     

顾锦城  李文钦  林嘉信  冯湘珠  施维新 《海洋科学》1989,13(6):16-22

本文采用动电位极化、线性极化、电偶电流和高压釜挂片失重等法,研究了含氮、硫有机缓蚀剂和/或Me~(2+)对X60钢在CO_2饱和的盐水溶液中的缓蚀作用。结果表明,含氮、硫的有机缓蚀剂在缓蚀过程中,开始是以抑制阳极过程为主,随后是以抑制阴极过程为主的混合型缓蚀剂。如与Me~(2+)复配使用,能明显地提高缓蚀效能。  相似文献   

A map series of the Southern East Pacific Rise and its flanks, 15° S to 19° S     

Daniel S. Scheirer  Ken C. Macdonald  Donald W. Forsyth  Stephen P. Miller  Dawn J. Wright  Marie-Hélène Cormier  Charles M. Weiland 《Marine Geophysical Researches》1996,18(1):1-12

Four large-scale bathymetric maps of the Southern East Pacific Rise and its flanks between 15° S and 19° S display many of the unique features of this superfast spreading environment including abundant seamounts (the Rano Rahi Field), axial discontinuities, discontinuity migration, and abyssal hill variation. Along with a summary of the regional geology, these maps will provide a valuable reference for other sea-going programs on-and off-axis in this area, including the Mantle ELectromagnetic and Tomography (MELT) experiment.  相似文献   

中国近海海水中几种微量金属离子的分布研究     

顾宏堪  刘明星  包万友  张星君  王琦  郭如新  曾昭文 《海洋科学集刊》1978,(13):1-7

中国近海海水中的锌等微量元素，尚未进行过较为广泛而可靠的分布研究。极为零星的资料，还是近几年来在沿岸进行污染调查时，用陈旧的方法测定的。 世界海洋海水中微量元素的含量，不同文献报道的数据，常有一定的差别。这是自然变化，抑方法误差(包括所测形态)，是值得研究的。 本文采用单池示差反向极谱法，比较广泛而可靠地研究了中国近海海水中,锌等微量，元素的离子(和不稳定络合物)的地球化学分布。测定锌、铅、铜、镉时，样品不加任何试剂，因而避免了元素存在形态的转移及被测离子的带入或损失。  相似文献   

Prolonged Magmatic and Tectonic Development of the Caribbean Igneous Province Revealed by a Diving Submersible Survey     

Mauffret  Alain  Leroy  Sylvie  Vila  Jean-Marie  Hallot  Erwan  Mercier de Lépinay  Bernard  Duncan  Robert A. 《Marine Geophysical Researches》2001,22(1):17-45

Using the diving submersible survey NAUTICA we investigated the central part of the Caribbean large igneous province (CLIP) to observe and sample internal portions of this proposed oceanic plateau. Most of the samples are gabbroic and doleritic rocks; basalts are scarce. Radiometric dating by ⁴⁰Ar/³⁹Ar incremental heating experiments indicate that the intrusive rocks are Campanian in age (81–75 Ma). In some places these intrusive rocks underlie older Santonian (85–83 Ma) extrusive basaltic rocks, suggesting that the Campanian rocks represent a sill injection and an underplating episode. Results of the diving program supplemented by information from ODP and DSDP drilling sites document a 20 m.y. period (94–75 Ma) of igneous activity in the submerged portion of the Caribbean large igneous province (CLIP). In the northern part of the Beata Ridge late Campanian and/or post Campanian uplift is documented by prominent Maastrichtian (71–65 Ma) erosion and the establishment of a Paleocene-middle Eocene (65–49 Ma) carbonate platform. During and after the uplift an extensional period is indicated by seismic images and the subsidence (3 km depth) of the carbonate platform. Paleocene ages (55–56 Ma) determined on some volcanic samples are attributed to localised decompression mantle melting that accompanied the extension. We document a prolonged period of magmatic and tectonic events that do not fit with the current models of short-lived plateau formation during mantle plume initiation but shares many similarities with the constructional histories of other oceanic large igneous provinces.  相似文献