Circulation and currents in the southwestern East/Japan Sea: Overview and review     

K.-I. Chang  W.J. Teague  S.J. Lyu  H.T. Perkins  D.-K. Lee  D.R. Watts  Y.-B. Kim  D.A. Mitchell  C.M. Lee  K. Kim 《Progress in Oceanography》2004,61(2-4):105

A review is made of circulation and currents in the southwestern East/Japan Sea (the Ulleung Basin), and the Korea/Tsushima Strait which is a unique conduit for surface inflow into the Ulleung Basin. The review particularly concentrates on describing some preliminary results from recent extensive measurements made after 1996. Mean flow patterns are different in the upstream and downstream regions of the Korea/Tsushima Strait. A high velocity core occurs in the mid-section in the upstream region, and splits into two cores hugging the coasts of Korea and Japan, the downstream region, after passing around Tsushima Island located in the middle of the strait. Four-year mean transport into the East/Japan Sea through the Korea/Tsushima Strait based on submarine cable data calibrated by direct observations is 2.4 Sv (1 Sv = 10⁶ m³ s⁻¹). A wide range of variability occurs for the subtidal transport variation from subinertial (2–10 days) to interannual scales. While the subinertial variability is shown to arise from the atmospheric pressure disturbances, the longer period variation has been poorly understood.Mean upper circulation of the Ulleung Basin is characterized by the northward flowing East Korean Warm Current along the east coast of Korea and its meander eastward after the separation from the coast, the Offshore Branch along the coast of Japan, and the anticyclonic Ulleung Warm Eddy that forms from a meander of the East Korean Warm Current. Continuous acoustic travel-time measurements between June 1999 and June 2001 suggest five quasi-stable upper circulation patterns that persist for about 3–5 months with transitions between successive patterns occurring in a few months or days. Disappearance of the East Korean Warm Current is triggered by merging the Dok Cold Eddy, originating from the pinching-off of the meander trough, with the coastal cold water carried Southward by the North Korean Cold Current. The Ulleung Warm Eddy persisted for about 20 months in the middle of the Ulleung Basin with changes in its position and spatial scale associated with strengthening and weakening of the transport through the Korea/Tsushima Strait. The variability of upper circulation is partly related to the transport variation through the Korea/Tsushima Strait. Movements of the coastal cold water and the instability of the polar front also appear to be important factors affecting the variability.Deep circulation in the Ulleung Basin is primarily cyclonic and commonly consists of one or more cyclonic cells, and an anticyclonic cell centered near Ulleung Island. The cyclonic circulation is conjectured to be driven by a net inflow through the Ulleung Interplain Gap, which serves as a conduit for the exchange of deep waters between the Japan Basin in the northern East Sea and the Ulleung Basin. Deep currents are characterized by a short correlation scale and the predominance of mesoscale variability with periods of 20–40 days. Seasonality of deep currents is indistinct, and the coupling of upper and deep circulation has not been clarified yet.  相似文献   

青藏高原中部湖泊沉积物中Zr/Rb值及其环境意义   总被引：14，自引：1，他引：14  

陈诗越  王苏民  金章东  沈吉 《海洋地质与第四纪地质》2003,23(4):35-38

由于青藏高原及其周边地区构造复杂,湖泊沉积物中的粒级差别很大,单一的测量方法往往难以奏效。Rb、Zr是表生地球化学过程中的稳定元素,但它们之间也存在显著差别,Rb一般富集在细颗粒中,Zr则在粗颗粒中含量较高。研究发现,湖泊沉积物中Zr/Rb比值与粘土(<2μm)含量存在显著相关,Zr/Rb值反映了湖泊沉积物的粒度大小。Zr/Rb比值所揭示的青藏高原中部280万年来经历的3次大的环境演化过程与岩性变化、孢粉指标反映的环境特征是一致的。  相似文献   

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin     

Chandralata Raghukumar  G. Sheelu  P. A. Loka Bharathi  Shanta Nair  C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.  相似文献   

白云凹陷地球物理场及深部结构特征   总被引：13，自引：2，他引：13  

吴湘杰  周蒂  庞雄  郝沪军  申俊 《热带海洋学报》2005,24(2):62-69

珠江口盆地白云凹陷是南海最具代表性的第三系深水陆坡沉积区。以穿过白云凹陷中部的一条深反射地震剖面(14s)为研究基础，采用综合地球物理研究方法分析了该区地球物理场特征，根据重力异常平面等值线勾画了白云凹陷的形态，并提取该测线相对应的重磁剖面数据，利用重磁资料和地震剖面进行了综合反演。以深剖面地震资料建立了地质模型，利用所得的重力数据进行了研究深部结构的正演拟合，实测与计算值拟合较好，支持中生代俯冲洋壳存在的观点；同时结合地震资料对深部结构进行了分析，该区莫霍面由陆向海抬升，呈阶梯状变化，地壳厚度逐渐减薄，具有大陆边缘陆壳向洋壳过渡的特征。根据地质模型还进行了变密度综合反演拟合来分析基底岩性特征，该区基底主要为中酸性岩浆岩，部分为变质岩和基性火山岩，岩石密度由陆向洋逐渐减小，磁性体分布不均。  相似文献   

南四湖,东平湖资源综合开发问题探讨   总被引：1，自引：0，他引：1  

杨林芳  王有邦 《海洋湖沼通报》1994,(4):35-41

南四湖，东平湖是华北重要的淡水湖，湖区自然条件优越，资源丰富，有巨大开发潜力。本文分析湖区资源特征，开发利用现状和存在问题，提出合理开发利用途径与对策。  相似文献   

东平湖畔涝洼荒地渔农牧综合开发利用措施的探讨     

姜晨钟  蔡绍柱 《海洋湖沼通报》1993,(1):60-63

东平湖畔涝洼地年仅亩产细苇400—500kg,价值10—20元。采用渔农牧综合开发利用的措施,亩产鱼、粮、猪1000kg。其措施为: 1.改涝洼荒地为台田、鱼池。2.台田种粮食。3.鱼池采用光合细菌微生物技术并产体养殖,多种鱼及蚌、珍珠等。4.产品循环利用。粮食作物的副产品做猪饲料;猪粪做鱼饲料肥料;鱼粪回田做作物的肥料。  相似文献   

Does subterranean flow initiate mud banks off the southwest coast of India?     

K. K. Balachandran 《Estuarine, Coastal and Shelf Science》2004,59(4):589-598

Coastal waters off the southwest coast of India draw special attention because of the occurrence of mud banks at certain locations during southwest monsoon period. The present study puts forward a hypothesis of a subterranean flow, which could be a plausible mechanism to initiate the mud banks. The subterranean flow is believed to be coupled with activated trending faults and originate from the adjacent watershed (Vembanad Lake) separated from the sea by a narrow strip of land where submerged porous lime shell beds are present. When the lake water injection occurs through the fault, the mud/clay gets excited by its thixotrophic properties (as the overlying water looses its electrolyte) and transforms into a flowing fluid. The lowering of salinity due to the introduction of fresh water keeps the mud suspension in the water column for longer duration, leading to the formation of mud banks. The idea of subterranean flow through lime shell beds initiating formation of mud banks may apply globally to any coastal regions hugged by wetlands and of similar geological conditions.  相似文献   

Impact of Sea-Land Interaction on Evolution of Taihu Lake     

孙金华  陆桂华 《中国海洋工程》2006,20(1):173-178

1 .IntroductionFor Lakes near the middle andlower reaches of the Yangtze River ,theformationof lake basinsisgreatly affected by geological structures ,andthe interaction betweenrivers and seas .The Taihu Lakeis locatedinthelow-lying plain nearthe east coa…  相似文献   

上新世——早更新世青藏高原北缘隆升的磁性地层学证据   总被引：9，自引：0，他引：9  

郑洪波  陈惠忠  靳鹤龄  李孝泽  董光荣 《海洋地质与第四纪地质》2002,22(2):57-62

对新疆叶城剖面西域砾岩及下伏第三纪地层的磁性地层学研究表明 ,西域砾岩的沉积时代为晚上新世至早更新世 ,磁性地层年龄为 3.5至 <1.8Ma。阿图什组沉积于早上新世 ,古地磁年龄为 4 .6～ 3.5 Ma。阿图什组以砂岩和粉砂岩为主夹薄层砾岩 ,为河流相及冲积扇前缘相。西域砾岩以厚层砾岩为主夹风成粉砂岩 ,为典型洪积—冲积扇堆积。西域砾岩的沉积反映了青藏高原北缘晚上新世至早更新世强烈的隆起和剥蚀  相似文献   

关注苏皖南部地区海相油气资源          下载免费PDF全文

范小林 《江苏地质》2008,32(1):16-18

据苏皖南部地区地表露头及部分井下所发现的海相油气显示表明,这里存在海相油气资源勘探远景,关注这一地区的海相油气资源,如何开展和寻找这类油气资源,将有利于该地区区域性经济建设的可持续发展。  相似文献