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1.
浮游生物和大型底栖动物参与水体营养物循环, 影响着污染物的迁移转化与沉积物的稳定性, 对海洋生态系统的能 流和物流起着至关重要的作用。为系统了解渤海海域浮游生物和大型底栖动物多样性与优势种的时空变化状况, 本研究以生 态监测调查结果为依据, 站位重点布设在渤海海域重要的河口、海湾、海岛周边海域以及渤海中部海域, 同时结合相关历史 资料, 对渤海海域的浮游生物和大型底栖动物的种类组成 、密度 、生物多样性指数 、优势种等的变化趋势进行了分析。从 2016—2018 年浮游植物的细胞密度空间分布可以看出, 细胞密度均值在滦河口-北戴河海域相对较高, 而在锦州湾 、莱州湾 和庙岛群岛海域相对偏低。渤海浮游植物多样性在各调查海域之间相差不大, 但渤海湾海域的浮游植物多样性呈现明显的逐 年下降趋势。浮游动物细胞密度在滦河口-北戴河海域相对偏高, 其余各海域差别不大。2016—2018 年, 浮游动物多样性在 双台子河口 、渤海湾 、黄河口海域明显增加, 大型底栖动物群落物种数在渤海湾 、黄河口 、莱州湾和庙岛群岛均呈减少趋 势, 大型底栖动物多样性在锦州湾 、滦河口-北戴河的水平偏低, 在渤海湾有所下降, 耐污能力较强的多毛类成为目前渤海 近岸海域大型底栖动物最主要的优势类群。通过与历史数据对比可知, 2014—2018 年, 渤海浮游植物及浮游动物的群落种 类数、密度 、多样性指数总体变化不大, 主要优势种基本一致, 但大型底栖动物种类数 、生物量和密度总体上呈减少趋势, 主要优势种类由软体动物转变为环节动物多毛类。本研究丰富了渤海海域浮游生物和大型底栖动物群落的研究, 并为渤海生 态系统的健康评价与生物多样性保护提供了数据支持, 对合理开发海洋生物资源具有一定的指导意义。 相似文献
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用逐步稀释法对北冰洋研究区10个沉积物岩芯(计189份样品)的厌氧细菌(AAB)进行分析,用改进的ZoBell 2216号培养基,在4 ℃和25 ℃温度中分别培养3周以上,根据培养结果统计样品中厌氧细菌的检出率与含量,分析厌氧细菌含量的分布情况.结果表明,4 ℃时AAB检出率为85.71%,含量范围 0~2.40×109 个·g-1,平均4.42×107 个·g-1;25 ℃时检出率为93.05%,含量范围0~1.10×109 个·g-1,平均5.31×107 个·g-1,略高于4 ℃时的平均值.研究表明研究区岩芯中广布AAB;温度的提高,可能提高AAB的相关指标;沉积物深度增加可能有利于AAB生长,但太深也不利于AAB生长,呈中层增高现象,但并不规则;在一定水深范围内,水深增加也有利于AAB的生长.同时给出了研究区内不同海域AAB分布差异. 相似文献
3.
南海莺歌海盆地形成机制的物理模拟 总被引：2，自引：3，他引：2
莺歌海盆地位于印支板块和华南板块的拼接带，红河断裂带的海上延伸带上，构造演化十分复杂，由于盆地沉积厚度巨大，泥流体底辟发充,肝震勘探难以直接揭示盆地内部深层的构造面貌，因而对盆地形成与构造演化的认识存在明显的分歧，利用常用的三维比例沙箱模型，对盆地的形成机制进行了物理模拟，结果表明莺歌海盆地的形成可分3个阶段，自50MaB.P，或更早开始，在沿红洒断裂带带伸分量的左旋错动和印支地块的顺时针旋转的联合应力场作用下，形成了莺歌海盆地的断陷格架，大约21MaB.P.之后在纯左旋错动阶段叠加了压扭应力场，形成了盆地西北部的反转构造，约5MaB.P.之后发生右旋错动，带来了盆地内新一轮的快速沉积，根据盆地内最老和最新的沉积中心之间的距离，推测沿红河断裂带的左行位错约200km. 相似文献
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This paper, the second part of further analyses of the structure of the typhoon, mainly discusses the distributions of temperature and moisture fields of typhoon No. 7507. The result has shown that the typhoon developed from the warm-core disturbance. The height of maximum warming is highest (300 to 250 hPa) during the mature stage. There is a dry layer capping the typhoon during the initial stage. Once the typhoon rapidly developed, the dry layer was destroyed. A deep saturation layer eventually occurred in the central region of the typhoon. Meanwhile, the dry air from the China main continuously intruded into the outer region in the western and northwestern parts of the typhoon.The initial eyewall of the typhoon sloped outward with increasing height, and then became nearly vertical below 12 km level. This was closely associated with convective activity. The convective instability had been mostly released during the growing stage of the typhoon and stratification rapidly tended to moist neutralization. 相似文献
6.
利用已经过验证的高分辨率三维海洋动力模型FVCOM,根据1984—2014年内伶仃洋的围填海变化情况,结合情景模拟案例,研究分析围填海对伶仃洋水流动力的影响,探究截流式和顺流式围填海对伶仃洋不同季节的水平余流场、垂向环流结构以及潮汐变化过程的影响。研究结果表明,围填海对伶仃洋的余流流向没有明显影响,但对余流速有较大的影响。在水平方向上,截流式围填海使得周边海域的余流速明显增大,增幅在0.02～0.25 m/s不等,其中口门区域受到的影响最大;相较于底层流场,表层流场受围填海的影响相对更大,围填海以南的较远海域在表层出现一条强度逐渐减弱的流速减小带,减幅在0.02～0.15 m/s不等,且影响范围与流场的分布密切相关,在夏季向南延伸,在冬季向西南延伸。顺流式围填海的影响则主要分布在伶仃洋两侧沿岸,并且不同季节的影响特点有一定区别,在夏季使得内伶仃洋东岸海域流速增大,但在冬季使其流速减小,变化幅度均在0.02 m/s以上。在垂直方向上,围填海使口门区域余流的纵向流速梯度增加,并且改变了伶仃洋余流的垂向分布情况,总体表现为远离围填海的海域表、底层余流的流速减小,中上层余流的流速增大;与此同时,围填海大幅度改变了周边海域的横向流速,并且在伶仃水道、矾石水道等区域产生了新的横向环流。围填海使得河口至围填海的余水位明显上升,使得伶仃洋海域的余水位下降,余水位梯度的增大是围填海周边余流速增大的主要原因。另外,围填海影响了伶仃洋的潮汐变化过程。在大潮期间,围填海改变了伶仃洋海域涨落潮时的潮流流速,使得周边海域落急流速增加,较远海域落急流速减小,而涨急流速都减小;同时,围填海使得海域涨落潮时的潮位受到一定影响。围填海最终使得伶仃洋的潮汐相位提前了20～35 min。 相似文献
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Three completing methods were introduced in this paper. The data were completed from 1983 to 1988 at the KL and PTC stations. The completed data were called original data. The completing methods were the transfer function with fixed-parameters then built the Transfer Function (TF) model between the two stations. The TF model was used to estimate the wave data of the future. The difference of the estimated data and the original data were conferred in this paper. Two types of forecasting differences were discussed here: (1) the input data year increases from 1 to 6 years, and the difference of the estimated data and the original data were then compared. (2) Use one-year data as the input series to forecast the data of the next five years, and then compare the differences of the estimated data and the original data. After comparing the differences we can know the results. The mean value and the standard deviation of the differences decrease and go more stable as the quantity of the input data year increases. The mean value and the standard deviation of the differences increase and go more unstable as the quantity of the forecasted data year increases. This model can be used to forecast the wave data. 相似文献
8.
Pierre Cervenka Ute Christina Herzfeld Christian De Moustier 《Marine Geophysical Researches》1994,16(6):407-425
When isobath maps of the seafloor are constructed with a bathymetric sidescan sonar system the position of each sounding is derived from estimates of range and elevation. The location of each pixel forming the acoustic backscatter image is calculated from the same estimates. The accuracy of the resulting maps depends on the acoustic array geometry, on the performances of the acoustic signal processing, and on knowledge of other parameters including: the platform's navigation, the sonar transducer's attitude, and the sound rays' trajectory between the sonar and the seafloor. The relative importance of these factors in the estimation of target location is assesed. The effects of the platform motions (e.g. roll, pitch, yaw, sway, surge and heave) and of the uncertainties in the elevation angle measurements are analyzed in detail. The variances associated with the representation (orientation and depth) of a plane, rectangular patch of the seafloor are evaluated, depending on the geometry of the patch. The inverse problem is addressed. Its solution gives the lateral dimensions of the spatial filter that must be applied to the bathymetric data to obtain specified accuracies of the slopes and depths. The uncertainty in the estimate of elevation angle, mostly due to the acoustic noise, is found to bring the main error contribution in across-track slope estimates. It can also be critical for along-track slope estimates, overshadowing error contributions due to the platform's attitude. Numerical examples are presented.On leave at the Naval Research Laboratory, Code 7420, Washington D.C. 20375-5350, U.S.A. 相似文献
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Initial stage of incompressible liquid impact onto a corrugated elastic panel with account for compressible gas trapping between the corrugations is studied. The liquid free surface is flat and parallel to the panel before impact. The impact velocity is constant in this study. The corrugations are modelled as identical rigid short structures on the surface of the flat panel. The panel is either of infinite or finite length. There are only two corrugations which are placed symmetrically on the panel. Only a part of the panel between these two corrugations is elastic. The liquid free surface closes the gas cavity between the two corrugations at the initial instant of impact and compresses the gas before the fluid comes in contact with the elastic part of the panel. The elastic deflections of the panel are caused by gas pressure in the cavity. The elastic deflections modify both the pressure in the cavity and the hydrodynamic pressure distribution along the wetted part of the panel. The hydroelastic problem is solved within the Wagner approach. The effect of gas compressibility on the elastic behaviour of the corrugated elastic panel is investigated. It is shown that the pressure in the gas cavity and elastic deflections grow beyond all bounds for the panel of infinite length and are finite if the panel is of finite length. The present model is relevant for the strength assessment of the cargo containment system (CCS) in the tanks of LNG carriers. 相似文献
11.
我们于1975年对台湾海峡南部进行海底地形和底质调查研究时发现:1.台湾浅滩发育着水下沙丘群。2.陆架地形受现代环境的作用,正经历着冲刷、侵蚀和堆积的再改造过程。3.陆架边缘曾发生了巨大的滑坡。其原因是陆源物质供应严重缺乏,在风浪和各种流系作用下,使沉积物不断进行分异作用,再加上自1938年以来多次发生5—7级海底地震而导致滑坡,滑坡又促使沉积物向深水搬运,加速陆架地形的冲刷。 相似文献
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《Coastal Engineering》2001,42(1):53-86
A numerical model is used to simulate wave breaking, the large scale water motions and turbulence induced by the breaking process. The model consists of a free surface model using the surface markers method combined with a three-dimensional model that solves the flow equations. The turbulence is described by large eddy simulation where the larger turbulent features are simulated by solving the flow equations, and the small scale turbulence that is not resolved by the flow model is represented by a sub-grid model. A simple Smagorinsky sub-grid model has been used for the present simulations. The incoming waves are specified by a flux boundary condition. The waves are approaching in the shore-normal direction and are breaking on a plane, constant slope beach. The first few wave periods are simulated by a two-dimensional model in the vertical plane normal to the beach line. The model describes the steepening and the overturning of the wave. At a given instant, the model domain is extended to three dimensions, and the two-dimensional flow field develops spontaneously three-dimensional flow features with turbulent eddies. After a few wave periods, stationary (periodic) conditions are achieved. The surface is still specified to be uniform in the transverse (alongshore) direction, and it is only the flow field that is three-dimensional.The turbulent structures are investigated under different breaker types, spilling, weak plungers and strong plungers. The model is able to reproduce complicated flow phenomena such as obliquely descending eddies. The turbulent kinetic energy is found by averaging over the transverse direction. In spilling breakers, the turbulence is generated in a series of eddies in the shear layer under the surface roller. After the passage of the roller the turbulence spreads downwards. In the strong plunging breaker, the turbulence originates to a large degree from the topologically generated vorticity. The turbulence generated at the plunge point is almost immediately distributed over the entire water depth by large organised vortices. Away from the bed, the length scale of the turbulence (the characteristic size of the eddies resolved by the model) is similar in the horizontal and the vertical direction. It is found to be of the order one half of the water depth. 相似文献
14.
胶州湾浮游植物粒级结构及其时空变化 总被引：1，自引：0，他引：1
基于2003—2010年间对胶州湾分粒级叶绿素a浓度的连续观测,系统研究了胶州湾浮游植物粒级结构的季节变化、年际变化及长期变化特征。结果表明,胶州湾表层浮游植物粒级组成以小型和微型浮游植物为主,其浓度由东北部和北部向湾中间及湾外逐渐递减。不同区域分粒级叶绿素a浓度的季节与年际变化规律相似。小型和微型浮游植物表现出明显的双峰型季节变化,小型浮游植物的高峰值通常出现在冬季,而微型浮游植物则出现在夏季。长期变化结果表明,冬季小型浮游植物所占比例自90年代起表现为增加的趋势,而夏季的变化规律与冬季相反,自1998年开始,小型浮游植物所占比例下降,微型浮游植物比例有所上升。春季和秋季小型和微型浮游植物的贡献率没有表现出明显的升高或降低趋势,但微微型浮游植物的贡献率在2000年之后显著低于2000年之前。统计分析结果表明,温度、营养盐浓度与结构是影响胶州湾浮游植物粒级结构变动的重要因素。 相似文献
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《Coastal Engineering》2006,53(2-3):255-263
To study the adaptation of the morphology of the Frisian Inlet after basin reduction an aggregate model is developed. In the model, especial attention is given to the sand transport to the down-drift coast. In developing the model the inlet system is divided into three elements, the ebb tidal delta, the Zoutkamperlaag and the tidal flats. Based on observations during the first 18 years after basin reduction the adaptation time scale of the tidal flats is expected to be much larger than that of the ebb tidal delta and the Zoutkamperlaag, essentially reducing the inlet schematization to a two-element system. The dependent variables in the model are the sand volume of the ebb tidal delta and the water volume of the channel. The governing equations are non-linear and for quantitative accurate results are solved numerically. To demonstrate the nature of the solution the equations are linearized assuming the morphological state is close to equilibrium. The linearized equations are solved analytically and the solution is applied to a hypothetical case where the tidal prism of the Frisian Inlet is reduced by 10%. From the analytical solution it follows that the adaptation of the volumes of the two elements, delta and channel, is governed by two system time scales. These system time scales are functions of two local time scales. The local time scales pertain to the adaptation of one element assuming the other element has reached equilibrium. Because there are two system scales the adaptation of the volumes of the delta and channel is not exponential and is not necessarily monotonic. For example, initially the transport of sand to the down-drift coast is larger than the long-shore sand transport entering the inlet system from the up-drift coast, then becomes smaller and after some time increases again to reach the value of the up-drift long-shore sand transport. Comparison of the numerical solution for the actual reduction in tidal prism of 30% with the analytical solution for the 10% reduction in tidal prism shows qualitatively the same results. 相似文献
16.
紫菜体细胞发育与分化的研究 总被引：6，自引：1，他引：6
本文研究了紫菜体细胞的发育与分化。根据体细胞后代的形状、有无假根、颜色、色素体形状、细胞大小和排列方式以及最终分化趋势等,墰紫菜体细胞分8种发育类型。各种发育类型的百分数与藻体的日龄、大小及部位有关。日龄、体长越长,正常苗百分数越低,畸形苗和细胞团的百分数越高。随着藻体部位的上移,正常苗和畸形苗百分数下降,细胞团百分数上升。 相似文献
17.
Yasuo Matsukawa 《Journal of Oceanography》1979,35(2):118-125
A mechanism of the Kuroshio Meander is discussed by comparing some observed characteristics of the Kuroshio path with short- and long-term variations of the wind field over the North Pacific. It is suggested that the meander is caused by the blocking of the Kuroshio current by the Izu-Ogasawara Ridge. The blocking occurs when the depth of the main current increases or when the vertical shear becomes weak. These structural variations are closely related to the supposed baroclinic response of the North Pacific Subtropical Gyre to long-term variations of the wind field with a period of about 56 years. The Kuroshio Meander is initiated by a trigger meander at the offiing of Shikoku Island. The trigger meander is closely related to the supposed barotropic response of the gyre to short-term variations of the wind field with a period of about 34 months.The barotropic response of the North Pacific Subtropical Gyre to the short-term variation of the wind field yields the rapid change of the vertical structure of the Kuroshio current. This change generates the trigger meander in combination with the complicated pattern of the continental slope at the offing of Shikoku Island. The trigger meander is carried away toward the Izu-Ogasawara Ridge by the Kuroshio current. When the baroclinic response of the gyre is favourable for the blocking of the main current, the trigger meander and the cold eddy grow fed by the upwelling of the deep water of the Kuroshio which is blocked at the west of the ridge. The growing stops when the scale of the trigger meander reaches to the size of the steady Rossby wave which corresponds to the over-all mean velocity of the Kuroshio at that time, because the meander exceeding the size of the steady Rossby wave moves west-ward and separates from the ridge. Then the deep water of the Kuroshio at the west of the ridge which has been under the hard constraint of the cyclonic circulation in the form of the cold eddy becomes possible to flow arround the ridge. The upwelling stops and there remains only the general dissipation process of the available potential energy in the cold eddy. Then the meander gradually decreases its size and returns to the ridge when the meander becomes smaller than the steady Rossby wave at that time. It is blocked and begins to grow there again. In this way, the Kuroshio Meander behaves as a quasi-steady Rossby wave and stagnates at the west of the ridge until the baroclinic response of the gyre becomes unfavourable for the blocking of the Kuroshio current by the ridge. 相似文献
18.
针对浮式消波海流机样机测试时出现的问题,对其吃水深度线和叶片安装角度进行优化。根据装置结构特点,用Gambit建立了装置横截面的二维网格模型。根据浮式消波海流机实际工作环境,利用Fluent流体仿真软件,使用VOF(volume of fluid)两相流模型,分配空气相与液态水相在流域中的不同比例,来确定不同的吃水深度线。并且结合k-epsilon紊流模型建立模拟仿真环境。先对3种水线进行仿真分析,然后进行实验验证。通过分析对比装置的3种不同吃水深度线的模拟与实验结果,得到装置的最优吃水深度线为1/3水线。基于最优吃水深度线,分别对叶片的4种安装角度在相同的仿真环境中进行模拟仿真。利用仿真得到的扭矩数据,计算扭矩系数、功率系数,分析对比仿真数据以及仿真过程中扭矩趋势图得出4种叶片安装角度的最优角度是90°。吃水深度线决定了装置的消波能力,并且为叶片获能提供条件,叶片安装角度直接影响着装置的获能效率,所以最优的吃水深度线和叶片安装角度对海流机的消波能力和获能效率具有重要意义。 相似文献
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In this work the estimation of the load from the ice level on freeze into the ice structure is presented. Nowadays a big uncertainty exists when estimating a freeze-in effect. Considerable inexactness in the ice loads estimation could lead to great differences in the cost of the structures. Proper estimation of ice loads will reduce the cost of constructions. If the structure is freezing-in during no change of sea level — ice collars are occurring. Ice collars could lead to increase of the horizontal ice load from the ice level on the structure. The overview of the existing recommendations is presented. The thermo-dynamical task for calculating ice collar profile was investigated during the present work. The numerical methods were used to calculate an increase of the load when freeze-in effect occurs. Physical experiments were conducted to verify the models. Results of the work provide provisional method for estimation of the ice loads on the freeze into the ice structures. 相似文献
20.
The Bohai Strait is the only passage-way of the semienclosed Bohai Sea into the outer ocean. The various dynamical processes have great effects on both sides of the strait, especially on the Bohai Sea. Tidal current dominates in the strait, and among the tida! components the M, component tide is prevailing.The seawater in the strait is homogeneous vertically almost the whole year because of strong tidal mixing. The M, component tide was simulated numerically using two dimensional barotropical model, and the Eulerian tide-induced residual currents were also deduced. The results showed that the tidal currents were dominated by the coastal line and topography. There exist many eddies in the tide-induced residual current fields, particularly near the northern coast.On the basis of the simulation of the tidal currents, the movements of the water particles in the strait were tracked by means of Lagrangian techniques. Consequently the Lagrangian residual currents were obtained. Somewhat similar to the Eulerian 相似文献