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1.
中国陆架区属于堆积型浅海,其高速率沉积中的孢粉化石是地层划分,重建古气候古地理环境的重要指标。我国陆架海区孢粉学研究始于20世纪70年代,东部海区(渤海、黄海及东海陆架)第四纪孢粉研究的成果集中于20世纪80年代,而南海陆架海区与深海孢粉学研究自20个世纪90年代同步发展,已取得较显著成果。现代孢粉的来源及传播过程研究是正确解译地层孢粉的前提,我国陆架区主要通过表层沉积物孢粉组合变化探讨孢粉分布规律及传输路径,研究范围多集中在海区近岸或河口区,因此,覆盖更广陆架区的多角度(表层水体及空气孢粉)探讨孢粉物源及典型孢粉—藻类环境意义的工作亟待加强。同时,陆架区第四纪孢粉记录相对较少,多数研究集中于晚更新世或全新世阶段,且利用低分辨率的孢粉分析划分地层并定性恢复孢粉陆源区植被—气候及陆架海环境变化,深入认识我国陆架区的环境过程需要重视较长时间尺度或高分辨率的孢粉学研究。 相似文献
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南海东北部浮游植物对氮、磷加富的响应及与不同水团的关系 总被引：3，自引：1，他引：2
2014年5月搭载"实验3"号科考船对南海东北部海区进行氮、磷营养盐现场加富培养实验。水团分析的结果表明,南海东北部海区的环境参数随着空间的变化大体可以分成3个区域:近岸海区、陆架海区和陆坡、海盆海区。加富培养过程中近岸海区和陆坡、海盆海区浮游植物未发生显著变化。陆架海区浮游植物出现显著增长,该海区浮游植物加富氮、磷以后在48h出现反应,同时添加氮、磷显著促进了浮游植物的生长。各培养站位均检测到大量束毛藻,加富培养后迅速减少。营养盐的添加改变了海区浮游植物原有的硅甲藻比例与各粒级叶绿素比例,陆架海区培养后的改变最为明显,同时添加氮磷培养72h后,由甲藻为主的优势种如卡氏前沟藻(Amphidinium carterae)、光亮鳍藻(Dinophysis argus)、原甲藻(Prorocentrumsp.)转变成了以硅藻为主如绕孢角毛藻(Chaetoceros cinctus)、旋链角毛藻(Chaetoceros curvisetus)、放射角毛藻(Chaetoceros radicans)和丹麦细柱藻(Leptocylindrus danicus)。同时,加富实验表明磷酸盐的添加促进了陆架海区微微型浮游植物聚球藻的生长。 相似文献
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基于2014年5—6月对黑潮主流径及毗邻东海陆架海区的调查,研究了该区域水体中无机碳体系参数(p H、总碱度TAlk、溶解无机碳DIC及DIC/TAlk)的垂直与水平分布,在此基础上定量评估了黑潮输入对东海陆架海区无机碳收支的影响。结果表明,黑潮水体中DIC、TAlk与DIC/TAlk总体而言随水深增加而升高,p H降低,综合体现了浮游植物生产、海-气界面交换、有机物降解及Ca CO3溶解等过程的影响;上升流中心站位无机碳参数均受较深层水体上涌影响,与黑潮主流径其它站位略有不同。东海陆架海区外侧站位表层、30m层无机碳主要受台湾海峡暖流影响,高p H、低DIC/TAlk的黑潮表层水影响区域局限于东南部;而在底层,低p H、高DIC/TAlk的黑潮入侵流离开黑潮主流径向正北方延伸并抬升至钱塘江口附近;上升流对无机碳的影响持续至表层,其携带的黑潮中层水因此也可能进入陆架海区。水量模型估算黑潮水在5—10月间跨域陆架边缘向东海陆架区输入溶解无机碳总计58798.9×109mol,净输入达37382.9×109mol,而东海向外输出的无机碳绝大部分经由对马海峡进入日本海。 相似文献
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成国栋 《海洋地质与第四纪地质》1981,(1)
中国东部海域(东海、黄海、渤海)濒临西太平洋,绝大部分为水深小于200米的浅海陆架区,只东南部冲绳海槽为水深2000多米的半深海区。 一、中国东部海域的构造分区 渤海,黄海坐落于中朝古陆陆壳内部,海区基底为前古生代变质岩系,大致相当于陆上的泰山群、朐山群和朝鲜的太白群。中生代构造断裂活动使陆壳解体成块状结构,各块体的差异性运动,形成分割的沉降盆地,其基底最大埋藏深度达7—9公里。其上沉积了巨厚的中、新生代地层,主要是陆相碎屑岩,夹海相层,更新世为海陆交互相沉积。玉木冰期后,海平面上升,海水全面覆盖渤海、黄海区,为浅海相沉积。因此,渤海和黄海乃是欧亚板块内部由断陷形成的海区,称之为陆陷海区。 东海可分为两部分,一部分是陆架浅海区,另一部分是冲绳海槽半深海区。陆架浅海区水深在200米以内,地形平坦,是中国大陆向东海的自然延伸。其磁场特征与相邻的 相似文献
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东海北部冷涡区温盐度和海流观测的分析 总被引：1，自引：0，他引：1
济州岛西南的东海北部海区是东海陆架区的重要渔场之一;南去的黄海沿岸流、黄海冷水,北去的黄海暖流和台湾暖流等在这里相汇,夏季上层还有长江冲淡水的影响。该区地处浅海陆架区,受潮汐和气候的影响很大,水文要素不仅有季节变化和多年变化,且有明显的短周期变化。因此,该海区的海流、水文状 相似文献
6.
南极普里兹湾及其邻近海域水团研究 总被引：3，自引：3，他引：0
普里兹湾及其邻近海域是中国南大洋调查研究的传统优势海域与重点区域。围绕夏季表层水、冬季水、陆架水、绕极深层水、南极底层水、普里兹湾底层水、冰架水等研究海区主要水团的特征和分布,总结了前人在南极普里兹湾及其邻近海域基于调查资料开展的水团研究中所取得的成果。研究表明,前人在对陆架水的示性指标界定上,将陆架水是否区分为高盐陆架水和低盐陆架水存在较大争议,在高盐陆架水和普里兹湾底层水的定义上存在重叠;目前尚没有证据表明绕极深层水向南可以伸展到普里兹湾的陆架区域,也没有发现在普里兹湾附近海域生成南极底层水的直接证据。 相似文献
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长江和黄河每年输送近16亿t泥沙入海,是中国东部陆架海区最主要的陆源物质供应者.长江和黄河沉积物的物源识别一直是中国东部陆架海区沉积学热点问题之一,受到了广泛的关注.近年来,众多国内外学者运用矿物学、地球化学以及环境磁学等方法,对长江和黄河入海沉积物的物源识别做了深入研究,已经取得长足进展.在综合前人研究成果的基础上,... 相似文献
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陆架海灾害地质因素分类 总被引：8，自引：0，他引：8
对灾害地质因素给出了定义，并提出了一个成因分类法。其原则是根据灾害地质因素的成因分成６个类型，再据其对海关海洋工程的危害程度、直接或诱发性的特征划分两类。表中所列内容主要为目前在中国陆架海区已经发现的，但其分类原则也适合其他海区。 相似文献
11.
Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
12.
Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
13.
The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
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《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
16.
The relationship between the flux of exotic benthic foraminiferal tests (i.e. tests which are supplied from open-sea sources alone) in a tidal inlet and that of bulk sediment was analysed, which can be expressed as two first-order linear equations. According to this relationship, in order to determine net sediment transport directions in the entrance, the test concentration in surficial sediments of the tidal basin can be compared against a ‘ critical level ’. The critical level is determined for the conditions that no net transport of bulk sediment is present within the entrance. If the observed concentration (averaged over the tidal basin) is higher than the simulated critical level, then the net sediment transport is directed to landward. This method is applied to the analysis of net sand transport at Christchurch Harbour, a tidal inlet system located in southern England. In this investigation, concentrations of exotic foraminiferal tests in the surficial sediments of the tidal basin and ebb tidal delta area were obtained from the analysis of sea-bed sediment samples. A series of probable critical levels were calculated based upon the data sets with regard to: (1) sediment discharge from the rivers; (2) magnitude of sediment discharge within the entrance during the ebb; (3) the test concentration outside the harbour; (4) the thickness of the moving layer; and (5) two parameters associated with dispersive processes. The results show that the concentration in the tidal basin sediment is higher than a number of simulated critical concentrations for representative cases. Consequently, the high level of the concentration of exotic benthic foraminiferal tests within the harbour should be explained as a result of landward net transport of sands within the entrance. 相似文献
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Rahul Sharma 《Marine Georesources & Geotechnology》2000,18(3):237-250
Observations on seafloor features from subbottom profiling and seabed photography data show that the undisturbed and natural conditions before the benthic disturbance undergo a substantial change after operation of the disturber. The effects can be seen in the form of deep trenches and grooves, formed by the action of the sleds and the pumping of the sediment along its path, as well as sediment piles on either side of the track. Biological traces such as fecal coils, casts, tubes, burrows, and trails get obliterated in the areas of disturbance and resedimentation. The smooth, uniform nature of the seafloor observed in predisturbance phase shows microtopographic changes in and around the disturbed area as a result of sediment excavation and resettlement. Vertical mixing as well as lateral transport of sediment alter the geological, biological, physical, and chemical conditions on the seafloor, which need to be monitored over time to assess the process and the time taken for restoration of environmental conditions. 相似文献
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Vance P. Vicente 《Marine Ecology》1989,10(2):179-191
Abstract. Long-term changes in the distributional patterns of commercial sponges ( Spongia spp. and Hippospongia spp.) within the West Indian Region indicates that: 1) commercial sponges had a widespread distribution throughout the whole West Indian Region and were ubiquitous in very shallow water until about the first half of the present century; 2) they were fished commercially not only in the traditional northern Caribbean sites (Florida, Gulf of Mexico, Bahamas) but also in the Greater ( e. g. , Hispaniola, Jamaica) and Lesser Antilles; and 3) they became extinct throughout most of the Lesser Antilles ( e. g. , Puerto Rico, Vieques, St. Thomas) sometime during the first half of this century. Mortalities of spongiids within the Antilles were found to differ from other marine mortalities in that: 1) species disappeared from a large region; 2) species vanished from different habitats and depths; and 3) natural populations never recovered. Species richness patterns suggest that commercial sponge genera ( Spongia and Hippospongia ) evolved under slightly cooler elimatic conditions than those found at present, and that these extinctions occurred as a direct or indirect effect of positive thermal anomalies in sea surface and atmospheric temperatures between 1900–1950. The concept that species diversity is stable on a regional scale is questioned. 相似文献
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The behaviour of an axially pre-loaded cylindrical member of an offshore structure, hit by a supply ship, has been investigated. The effects of axial pre-loading on the dynamic properties of members, the extent of damage and propagation of dynamic instability in the tubular members have also been investigated. Numerical models have been validated using available experimental data from the literature although these are mostly static with no pre-loading. Axial pre-loading was found to change the dynamic characteristics of some cylindrical members quite dramatically while it had no significant effect on others. The study examined whether there was any change in the behaviour between local and global modes when the loading was dynamic rather than static. The effect of damping on the dynamic instability of axially pre-loaded tubes under lateral dynamic loads was also studied. It was observed that for some geometries the quasi-static response can be used to define the boundary between bounded and unbounded dynamic responses. The main contribution of this study, compared with previous investigations reported in the literature, is that both pre-loading and dynamic effects have been included. 相似文献