闽南—台湾浅滩大陆架海绿石的研究

闽南—台湾浅滩大陆架位于东海与南海的交界处,是台湾海峡向开阔的南海的过渡区。调查范围界于116°00′—118°30′E,21°20′—24°00′N之间。本文对表层沉积物中的海绿石进行了研究,共分析样品76个。     

东海大陆架沉积物中的放射虫

利用海洋沉积物中放射虫的研究资料来判別海底地层和解决与海洋学有关的问題, 系探索海洋资源的手段之一。近年来,一些国家对世界大洋的调查研究工作进展很快，目前,除北冰洋外；几乎对各大洋的大部分海域都进行了钻探取样。其中,用放射虫沉积岩样结合地层学进行分析划带的工作已有很大进展。东海大陆架范围辽阔,资源丰富,亟待开发利用,但对其海底情况过去了解较少。为配合当前渔场调查和海底矿产资源的探测,对海底沉积物及有关方面进行调查研究是急需的。本文就东海大陆架部分地区(东经121°30′-127°,北纬26°30′-32°30′；图1)海底沉积物中的放射虫进行研究整理、以供作海洋开发的基础资料。     

一种新矿物——钓鱼岛石的发现

1982,年中国科学院海洋研究所在东海海域进行了海底沉积物的调查;之后,对所取沉积物样品开展了多方面的研究工作,其中在表层碎屑矿物的研究中发现了一种新矿物。它产在东海东部的冲绳海槽南端,即中国台湾省东北50公里处的钓鱼岛附近(123°22′E,25°26′N)的海底表层沉积物中(见图)。它是在自然界中首次发现的一种新矿物,根据其产地命名为钓鱼岛石(Diaoyudaoite)。该矿物于     

东海海底表层沉积物中的碎屑矿物及其地质意义

为探讨东海海底表层沉积物中的碎屑矿物及其地质意义,首先有必要概略地了解东海海底自然地理与地质环境及近期演化史.东海陆架范围广阔,地形平坦,最宽处达960公里,我所实测资料表明,陆架区平均坡度58″,冲绳海槽西坡平均坡度1°10′00″,为世界上典型宽展陆架之一.陆架水动力条件复杂,既有低温低盐的沿岸流,也有高温高盐的暖流;既有周期性的潮汐流,亦有偶发性的风暴潮.著称世界的长江、黄河为本区带来了大量的陆源物质.据地震资料揭示,东海陆架新生界的厚度达6000米以上.     

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。     

冲绳海槽某些海底岩石的初步研究

冲绳海槽位于东海大陆架与琉球岛弧之间,曾被认为是西太平洋边缘的弧后盆地,是研究沟-弧-盆系的一个重要海区,也是研究现代半深海沉积及其沉积作用的有意义海区.国外对冲绳海槽的底质、地热流、地球物理场特征以及其形成与演化,做过大量调查、研究工作,真是众说纷坛,莫衷一是.我国对该海槽也曾做过一些调查,但其内容和范围均受到局限,尤其是对海底岩石的研究报导,就显得更少了.1980年8—9月间,由地质部海洋地质调查局和海洋地质研究所共同组队,对四角座标为:24°51.84′N、123°53.19′E;25°24.69′N、123°42.38′E;29°16.11′N、126°16.25′E;29°29.46′N、128°37.97′E的海区进行了一个航次的地质调查,除采得柱状样品外,还拖获了大量浮岩,并发现早全新世生物碎屑灰岩团块和少量英安岩、安山岩.本文对所获各类岩石的分布和特征进行了描述,对其中浮岩的岩石类型及其形成条件进行了较为系统的探讨,并总结了生物碎屑灰岩团块的特征,提出其归属应为海滩岩的新认识.工作中得到东海水产研究所“东方”号调查船惠赠标本;山东区调队王进聚、刘贵章等同志协助鉴定、照相;陈菊艳同志清绘图件;谢继哲副所长阅改文稿;文成后,承蒙宋叔和教授审阅、指导,均此致谢.     

东海海樽类数量分布及与环境的关系

提要根据1997—2000年东海23°30′—33°00′N、118°30′—128°00′E海域4个季节海洋调查资料,采用方差贡献和逐步回归分析方法探讨东海海樽类的数量变化和相应的动力学。结果表明,海樽类是东海浮游动物第二大类群,在数量上仅次于桡足类,其丰度春季最高,夏季次之,冬季最低;冬、春和夏季的东方双尾纽鳃樽(Thalia orientalis)和冬、秋季的小齿海樽(Doliolum denticulatum)是影响海樽类数量分布的主要优势种;海樽类高丰度区常位于暖流与各水团交汇处的偏暖流一侧,其数量变化的动力主要来自暖流势力的消长。海樽类在东海出现率较低,集群性强,较高丰度的分布仅局限在暖流势力范围内,其高丰度水域是东海暖流锋面的一个重要标志。     

东海沉积物中几种微量元素的分布和变化规律的研究

东海海底覆盖着一层疏松的沉积物,大体上在内陆架为细粒沉积,外陆架为粗粒沉积,陆坡和海槽区又分布着细粒沉积。从地球化学的角度来看,这些沉积物的组成与海洋中无机悬浮物的组成有着密切的关系。沉积物通过其沉淀和吸附,从海水中吸取微量金属元素。沉积物中,特别是沉积物表面的微量元素的氧化物,对海水中颗粒物质的化学行为有着很大的影响,其化学效应远比沉积物本身的大量化学组成所起的作用要大的多。所以,对沉积物中微量元素的组成及其分布和变化规律的研究,越来越引起地球化学工作者的重视。 本文根据近几年在东海海域采集的74个地质样品,用原子发射光谱法对沉积物中Ti,Cr,Mn,Ni,Cu,Ga和Ba等元素含量測定的数据,对它们的地球化学分布特征和变化规律进行了初步研究和探讨。研究区域位于北纬26°30''至32°30′和东经121°30′至129°00′之间,取样站位如图1所示。大部分样品是1977年和1978年取的样,少数是1974年和1975年取的样。本文所用测定方法与设备同参考文献[1]。     

东海精致真刺水蚤(Euchaeta concinna)种群生态特征

根据1997—2000年东海23°30′—33°00′N、118°30′—128°00′E海域4个季节海洋调查资料,采用聚集强度等生态学方法和回归方差贡献等统计分析方法,对东海浮游桡足类精致真刺水蚤自然种群特征进行了研究,并与1979—1980年资料进行比较。结果表明,精致真刺水蚤在东海的优势性主要表现在秋季;其丰度和优势度有显著的季节变化,依次为秋季>冬季>夏季>春季;除夏季东海北部近海丛生指标I为1·34外,冬、春和夏3季I均为负值,秋季I值最高,有明显的聚集现象。与20年前结果相比,东海精致真刺水蚤优势度和占浮游桡足类总丰度的比例有所上升,这种现象可能与全球气候变暖相关。底层水环境的变化和暖流势力的强弱是影响东海精致真刺水蚤数量分布的主要因子。     

黄海南部的海绿石

自生矿物作为沉积体形成环境的标志一直得到人们的重视,研究现代海绿石的形成条件对阐明古代有关岩石的生成环境是有重要意义的,但由于它成分复杂,颗粒细小,要搞清楚这方面的问题有一定困难。本世纪60年代初,有些作者曾对我国东海大陆架的海绿石作过一般性报道。近年来陈丽容等对东海沉积物中的此种矿物进行了研究,但关于黄海底质中海绿石的研究成果未见报道。本文主要阐述我们从1979年以来,对北纬35°30′至32°,东经121°至126°的黄海北部(共20个站位,见图1)的表层沉积物中海绿石的研究结果。     

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

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.     

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。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.     

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,     

Evaluation of the Risk of Marine Slope Instability: A Pseudo-3D Approach for Application to Large Areas

This article presents a methodology developed to evaluate the instability of submarine slopes that extend over a large area. Special attention was paid to (1) the complex geometry (bathymetry) and the expanse of the slope, (2) the heterogeneity of the sediment, and (3) the distribution of the pore pressure. The safety factor was considered as a spatially varying quantity. The General Formulation (GLE, Fredlund and Krahn 1977), which fully satisfies equilibrium conditions, was used for evaluating the stability of the marine slope. The submarine slope failure, which occurred on 16 October 1979 during the construction of the new Nice airport, was studied in order to test the developed model. Geotechnical parameters were taken from experimental tests carried out by IFREMER on 19 cores extracted at different depths (from 27 m to 1300 m) (Cochonat, Bourillet, and Savoye, 1993; Mulder et al., 1994). Many scenarios were proposed in order to explain the cause of the Nice slope failure (Habib, 1994). In this article, two of those scenarios were tested. Simulation results are presented and discussed.