陆丰13－1平台场地海底稳定性分析与评价

根据陆丰１３－１平台场地地形地貌、土质和土力学分析及实测海洋水文资料，采用沉积学－海洋水动力学－土力学综合研究方法，对海底沙波的成因及其稳定性作出分析与评价。文中提供的一些海底沉积物的地质分析、１４Ｃ测年等资料和采用的研究方法对今后南海北部大陆架的第四纪地质、海底沙波以及海底稳定性研究均有参考价值。     

海底沉积物分析测试方法标准的研究

依据海底沉积物分析测试方法标准研究的总体设计，完成了40个分析项目的21份验证报告，进行了实验室间精密度协作性检验工作，在海底沉积物CaCo3,H2Os^-，H2O^ 的分析方法研究中取得新进展，并建立了ICP－AES法测定海底沉积物中常量、微量、稀土元素分析方法。     

花东盆地晚中新世以来沉积演化特征

利用近年来在台湾东部海域采集的多道地震和多波速测深资料，对该海域花东海盆区晚中新世以来的沉积充填演化特征进行描述和分析。通过对花东海盆区域地形特征描述、层序地层格架的建立和地震剖面的解译，在本区晚中新世以来的沉积充填中刻画出6种典型地震相类型，并分析其对应的沉积相类型，包括浊积扇、浊积水道充填、块体流、沉积物波、海底峡谷－伴生沉积物滑塌变形－充填、深水扇沉积。结合地震相平面分布及垂向沉积相叠置关系，将晚中新世－第四纪沉积充填演化划分为3个阶段:晚中新世晚期开始受到块体流冲蚀阶段，到海底峡谷冲刷－沉积物失稳－峡谷充填－再侵蚀阶段，到峡谷输送的大量沉积物在上新世以来主要堆积发育了沉积物波、浊积扇、深水扇等沉积体系阶段。     

天然气水合物的聚集和形成及南海地质条件分析

天然气水合物目前已经成为世界范围的一个研究热点，而我国的天然气水合物研究起步则相对较晚，通过阅读国内外有关文献，总结了天然气水合物在海底的分布特征，聚集和形成机制，产状及其形成机理，甲烷羽的形成过程，天然气水合物在沉积物中的聚集位置通常有两种情况：一是较浅的沉积物（海底以下几米）中，受控于泥底辟，泥火山，断层等；二是较深的沉积物（海底以下几十米，甚至更深）中，受控于流体，当断层延伸至海底时，通常在水合物聚集处的上部发现甲烷羽，天然气以溶解气，游离气或分子扩散的形式运移，在温，压适宜的沉积物中，即水合物稳定带内聚集并形成水合物，水合物的形成过程是：最初形成晶体，呈分散状分布于沉积物中，之后逐渐聚集，生长成结核状，层状，最后形成块状，在细粒的浅层沉积物中，通常以较慢的速度生长，形成分散状的水合物；而在粗粒沉积物中，水合物通常呈填隙状，并且这种产状可能位于较深层位中，我国南海在温度，压力，构造条件，天然气来源等方面都能满足天然气水合物的形成条件，并且在南海也发现了一些水合物存在的标志，如似海底反射层（BSR）以及孔隙水中氯离子浓度的降低。因此，天然气水合物在我国南海海域可能有很好的前景。     

南黄海沉积物中自生黄铁矿的形态标型研究

得１９８９年采于南黄海的样品，通过实体显微镜、反应显微镜和电子显微镜对自生黄铁矿的集合体形和晶体形态进行研究，结合前人成果，对现代海底沉积物中自生黄铁矿集合体进行形态分类和成因－形态分类，在此基础上讨论其特征形态的成因及标型意义。研究表明，自生黄铁矿集合体形态可以分为聚莓、单莓和细粒３种，其中前二者可作为沉积物中自生黄铁矿和层控或沉积成因矿床黄铁矿集合体形态标型；成因－形态分类将黄铁矿集合体分为两     

台湾海峡西部海域表层沉积物m值与地层分布

由台湾海峡西部海域中表层积物的ｍ值分布和＾１４Ｃ测年资料，发现出露于该海域海底表层的沉积物有６层。其中层（３）是以韩江和九龙江古河口沉积物为代表的低海面时期的沉积物，形成于距今９０００－７０００ａ间，出露的古河口沉积物的ｍ值小于１０。层（４）为低海面前海面逐渐下降过程中形成的，沉积物的ｍ值为１０－２６．５，且由上向下渐增。其形成时代为距今１２５００－９０００ａ。层（２）为低海面后海由逐抬升过程中形     

中国黄海、东海和南海北部海底浅层沉积物声学物理性质之比较

黄海、东海和南海北部海底沉积物声学物理性质存在着差异,这与海区海底地质和沉积环境有关。取样所及的海底沉积物样品分析表明:黄海实验海区海底有6种沉积类型,东海实验海区海底有3种沉积类型,南海北部大陆架海区海底有6种沉积类型。三个海区的沉积物密度为1.48～2.03g·cm-3;沉积物含水量为10%～90%;沉积物孔隙度为65%～80%;沉积物纵波声速为1460～1916m·s-1;沉积物横波声速为115～611m·s-1。     

南海北部大陆架海底沉积物物理性质研究

用物理(声学的、工程地质的、扫描电子显微镜)等技术方法,综合分析了沉积物结构特征和工程力学性质,研究了颗粒接触、堆垒、孔隙等现象与物理性质之间的关系,得出了沉积物声学物理参数和应力一应变性质之间的关系。结果表明,南海北部大陆架海底沉积物有6种结构类型,其中混合接触结构类型的沉积物具有较高的抗压强度和声速,浅层海底存在着高、低声速分层的中尺度结构。     

南海东北部峡谷体系的地貌特征与发育控制因素

海底峡谷在全球陆缘广泛分布，是浅海沉积物向深海运移的主要通道，对于理解深海浊流触发机制、深海沉积物的搬运模式、深海扇的发育历史和深海油气资源勘探等均具有重要意义。本文基于高分辨率高精度的多波束测深数据，首次对南海东北部海底峡谷体系进行了研究，精细刻画了高屏海底峡谷、澎湖海底峡谷、台湾浅滩南海底峡谷和东沙海底峡谷等4条大型海底峡谷的地貌特征并分析其发育控制因素。海底坡度、构造运动、海山与海丘是影响南海东北部峡谷群走向与特征的重要因素，其中，海底坡度对于峡谷上游多分支与“V”字特征有显著的控制作用；构造运动是控制高屏海底峡谷走向的因素，澎湖海底峡谷的走向则与菲律宾海板块与欧亚板块碰撞有关，东沙海底峡谷的走向则与东沙运动相关，台湾浅滩南海底峡谷上段受NW向断裂构造的控制；海山的阻挡作用造成峡谷局部走向和特征改变。海底峡谷群输送大量陆源沉积物到深海盆并形成大面积的沉积物波，海山和沉积物波的发育导致东沙海底峡谷下段“回春”和转向。     

海底沉积物烃类气体地球化学异常识别与成因解释

烃类气体是海底渗漏烃的重要组分之一。它们在海底沉积物中主要以游离态和束缚态形式存在。测量海底沉积物烃类气体组成的方法有顶空气法、酸解烃法和热释烃法等。顶空气测量的是在海底沉积物中以游离态存在的烃类气体,酸解烃测定的是吸附在颗粒表面或存在内部包裹体中的束缚烃类气体,热释烃测定的是海底沉积物中被硅铝酸盐所吸附的束缚烃类气体。海底沉积物地球化学异常识别方法包括图解法和计算法等多种方法。海底沉积物地球化学异常成因主要包括有生物成因、热成因和混合成因等。利用烃类气体含量、组合及比值,结合同位素组成特征可以解释地球化学异常成因。     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

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.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

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.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

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.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

INFORMATION FOR AUTHORS

<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,     

Estimation of Sediment Properties during Benthic Impact Experiments

Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges.