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1.
胶州湾现代沉积速率和沉积通量研究 总被引：19，自引：0，他引：19
对胶州湾沉积岩心J39、J37和J94进行了210Pb的测定,绘制了岩心中210Pb的垂直分布图,岩心J37和J94的210Pb呈两段分布模式,岩心J39的210Pb呈三段分布模式。胶州湾西北部大沽河口外海域近百年来沉积速率为0 768cm/a,沉积通量为0 7716g/(cm2·a)。胶州湾中部沉积速率为0 64cm/a,沉积通量为0 65g/(cm2·a)。胶州湾口外J94站沉积速率为0 54cm/a,沉积通量为0 81g/(cm2·a)。结果表明,胶州湾海域210Pb活度与悬浮体含量密切相关,悬浮体含量高的区域,210Pb活度高;反之,悬浮体含量低的区域,210Pb活度低。根据210Pb的垂直分布、活度和沉积速率及悬浮体含量,结合历史资料,对胶州湾近百年来的沉积环境和物质扩散进行了探讨。 相似文献
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南黄海沉积速率和沉积通量的初步研究 总被引：16，自引：6，他引：16
1983—1986年,中美联合对南黄海进行了调查,利用同位素~(210)Pb方法测定了该海域的沉积速率和沉积通量,分别介于0.026—0.67cm/a和0.033—0.76g/(cm~2·a)之间。研究表明,山东半岛南侧是现代黄河物质大量沉积的场所,而在黄海暖流流经的地带和冷涡区,其沉积作用却较弱;物质来源和海流体系是控制该海域沉积速率和通量的主导因素。 相似文献
3.
海州湾南部近岸现代沉积速率及其沉积通量 总被引：1，自引：0，他引：1
对海州湾南部近岸3个柱状岩芯进行了210Pb的测定,绘制了岩芯中210Pb的垂直分布图。结果表明,柱-1岩芯表现为2个明显的沉积阶段,1-12 cm平均沉积速率为0.51 cm/a,12-57 cm的为0.18 cm/a,沉积通量分别为0.69和0.24 g/（cm^2·a）;柱-2岩芯平均沉积速率为0.64 cm/a,沉积通量为0.68 g/（cm^2·a）;柱-3岩芯平均沉积速率为0.67 cm/a,沉积通量为0.76 g/（cm^2·a）。沉积速率从北往南逐渐增大。造成这种空间分布规律的主要因素是沉积环境和物质来源,其次可能同海域位置、沉积物组分特征和海底地形有关。 相似文献
4.
采用Pb-Po法测定了楚科奇海陆架沉积物中210Pb的垂直剖面.应用双层模型研究210Pb分布,得到沉积速率(S)为0.145cm/a,沉积物堆积通量(FM)为78mg/(cm2·a),过剩210Pbex的沉积通量为6×10-3Bq/(cm2·a)[即0.36dpm/(cm2·a)].用中子活化分析方法和火焰原子吸收法分析测定了沉积物岩芯12个层段的重金属Cu、Pb、Zn、Cd、Cr、Co、Fe、Mn和V的含量,发现各层段之间重金属含量没有显著的区别.将本次分析结果和北冰洋其他一些陆架区的研究结果及页岩标准值相比较,发现楚科奇海沉积物中大部分重金属含量都相对较低.基于此可以推断,楚科奇海沉积物中重金属是源于地球化学过程的作用,没有表现出受到明显的人为重金属污染影响. 相似文献
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黄、渤海泥质沉积区现代沉积速率 总被引：47，自引：2，他引：47
利用α多道能谱仪对黄、渤海泥质沉积区岩芯的2 1 0 Pb放射性活度进行测定 ,并结合历史数据 ,对2 1 0 Pb放射性活度在岩芯中的垂向分布和现代沉积速率的平面分布进行了分析。研究区岩芯的2 1 0 Pb放射性活度垂向分布表现出 5种形式。从沉积速率来看 ,渤海东北部泥区、南黄海中部和东部泥区 ,以及北黄海中部泥区的沉积速率小于 0 .2cm/a ,为低速沉积区 ;黄河三角洲海域和莱州湾西部的沉积速率大于 1cm/a,为高速沉积区 ;山东半岛南部沿岸海域的沉积速率也较高 ;山东半岛成山头及苏北辐射沙脊群外缘海域的沉积速率为 0 ,属于无沉积区或侵蚀区。黄、渤海泥质沉积区现代沉积速率的分布特征的解释有待于沉积动力过程的深入分析 相似文献
6.
江苏固城湖近代沉积210Pb、137Cs计年及其环境意义 总被引：9，自引：0，他引：9
对江苏固城湖沉积柱状岩心进行了210Pb、137Cs测定,以研究湖泊沉积过程和人类活动的关系。137Cs剖面显示的蓄积峰和1986年前苏联切尔诺贝利核电站核泄漏相对应,由此获得的沉积速率为0.066 cm/a;同时,利用210Pb计年的CRS模式计算了固城湖20世纪初以来不同时段的沉积速率,结果表明,在上世纪60年代初沉积物堆积速率最高,达到0.187 g/(cm2.a),80年代后沉积速率趋于稳定,约0.067 cm/a,与137Cs结果相一致。对比洪湖沉积钻孔210Pb、137Cs分布后发现,洪湖137Cs分布和固城湖相似。其人类围垦最强烈的时期正好是其137Cs峰值减弱或消失的时间段,同时也是沉积速率最高的时期。可见人类活动的影响会导致放射性核素在垂直剖面分布的不同。 相似文献
7.
黑碳在渤海泥质区的百年沉积记录 总被引：2，自引：1，他引：1
在渤海泥质沉积区采集柱状沉积物样品,分析其黑碳含量和沉积通量,结合210Pb年龄测定,探讨百年尺度黑碳沉积通量的时间序列变化对区域人类活动的响应。结果表明:(1)研究区黑碳含量和沉积通量分别为0.24~0.49mg/g[平均为(0.32±0.07)mg/g]和0.026~0.053mg/(cm2·a)[平均为(0.040±0.008)mg/(cm2·a)],黑碳含量与我国东海内陆架等海区相当,但远低于美国港湾和瑞典大陆架等污染较严重地区;(2)黑碳通量在20世纪50年代-70年代中期和90年代初-90年代末出现两个明显的峰值,分别对应于两个阶段的生物质燃烧量和煤炭、石油等化石燃料燃烧量的急剧增加;而20世纪70年代末-80年代末较低的黑碳通量以及21世纪初黑碳通量下降的趋势则分别与黄河改道事件、我国能源利用技术提高及污染控制减排措施逐步实施等有关;(3)通过比较本文结果以及国内外其它海域和湖泊的研究资料,证明黑碳沉积记录可以作为一个良好的地球化学指标,用于评估人类活动对生态环境的影响历史。 相似文献
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辽东湾是渤海的三大湾之一,进入该区的主要河流有辽河、大凌河、滦河和六股河等，水深一般在10.2-35m之间，沉积环境很复杂。测定、研究该区现代沉积速率和沉积通量对沉积动力学的研究和海洋油气开发工程都有意义。
近年来,国内外学者在利用210Pb法测定江河、湖泊和海洋陆架的沉积速率等方面取得了有价值的成果。到目前为止,除在渤海锦州湾测得两个岩芯的沉积速率外(夏明等，1983),关于辽东湾大面积海域的现代沉积速率和沉积通量还未见报道。本文介绍了该区现代沉积速率和沉积通量,利用210Pb的垂直剖面,探讨该区近百年来的沉积作用和沉积环境,划分了沉积强度区。 相似文献
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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
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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
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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