黄海表层沉积物中硅藻分布与环境关系探讨

黄海表层沉积硅藻可划分为三个区:(1)滨岸-潮间带区,水深为20—30m,盐度为30.0‰,主要分布着以柱状小环藻为主的潮间带种类;(2)过渡区,包括黄海北部的大部和西南部,水深在30—50m之间,盐度为31.0—32.5‰,本区还可进一步划分为明盘藻、直链藻和辐裥藻三个亚区;(3)浅海区,包括黄海中北部和东南部,深度大于50m,盐度大于32.0‰,分布着以圆筛藻为主的组合,个别海区还见反常硅藻组合。光照、盐度和温度是影响硅藻分布最重要的因素,而反常硅藻组合的出现则可能与古地理条件有关。     

南海中部表层沉积硅藻分布的初步研究

本文通过对南海中部80个表层沉积物样品的硅藻分析,共鉴定硅藻129种,划分出结节圆筛藻-辐射圆筛藻-具槽直链藻-条纹小环藻组合、结节圆筛藻-楔形半盘藻-菱形海线藻-海洋菱形藻组合、结节圆筛藻-楔形半盘藻-海洋菱形藻组合等3个硅藻组合区。文章根据硅藻的数量分布,分析了其控制因素,并根据培氏根管藻和淡水硅藻分布,讨论了黑潮和陆地径流对本区的影响。     

南海深海表层沉积中的硅藻组合及其环境特征

定量分析了南海３３个１０００ｍ水深线以内的现代表层沉积样品中的硅藻,发现主要的种有菱形海线藻,短刺角毛藻,结节圆筛藻、长海毛藻,海洋菱形藻和条纹小环藻。根据硅藻主要种的百分含量,各站位硅藻丰度的变化以及其它一些特征,将３３个样品划分为５个硅藻组合,并着重研究这些组合与环境因素之间的关系。     

渤海中、南部表层沉积硅藻的定量分析

对取自渤海中、南部海底表层的44个沉积物样品进行了硅藻分析。样品中共含硅藻20属41种,主要是潮间带、沿岸性底栖或浮游种类,其中尤以具槽直链藻Melosira sulc-ata和小环藻Cyclotella最多见。对本区的表层沉积硅藻用多元统计方法进行分区,共划分出三区、两亚区,井与其他海区进行了比较。     

南海深海表层沉积中的硅藻组合及其环境特征

定量分析了南海３３个１０００ｍ水深线以内的现代表层沉积样品中的硅藻,发现主要的种有菱形海线藻Ｔｈａｌａｓｓｉｏｎｅｍａｎｉｔｚｓｃｈｉｏｉｄｅｓ、短刺角毛藻Ｃｈａｅｔｏｃｅｒｏｓｍｅｓｓａｎｅｎｓｉｓ、结节圆筛藻Ｃｏｓｃｉｎｏｄｉｓｃｕｓｎｏｄｕｌｉｆｅｒ、长海毛藻Ｔｈａｌａｓｓｉｏｔｈｒｉｘｌｏｎｇｉｓｓｉｍａ、海洋菱形藻Ｎｉｔｚｓｃｈｉａｍａｒｉｎａ和条纹小环藻Ｃｙｃｌｏｔｅｌｌａｓｔｒｉａｔａ。根据硅藻主要种的百分含量、各站位硅藻丰度的变化以及其它一些特征,将３３个样品划分为５个硅藻组合,并着重研究这些组合与环境因素之间的关系。     

中国南海表层沉积硅藻的分布及其与环境关系探讨

通过对中国南海62个站位表层沉积硅藻的分析,查明研究海区硅藻的种类组成及分布特点。共鉴定到硅藻56属的235个种(包括变种和变型),以热性外洋种为优势,伴有一定量的近岸广布种。总体上,南海硅藻丰度变化呈现从陆架向陆坡至海盆递增的趋势。根据表层沉积硅藻中具有指示意义的硅藻种的分布和生态变化,划分6个硅藻组合带,各组合分别反映不同的海洋环境,其分布主要受到海洋环流的影响,表现为黑潮暖流、印度洋暖水的入侵以及沿岸流对南海表层沉积硅藻分布的影响。与南海相邻海区硅藻种类比较结果表明,研究海区表层沉积硅藻种类组成与临近的菲律宾海域相似程度最大,其次是中国东海海域、太平洋东北部海域。     

《南海及沿岸地区第四纪孢粉藻类与环境分析》一书简介

南海是我国目前海上石油勘探与开发的重要海区,而海区及沿岸第四纪沉积研究,是海上石油开发的工程地质重要背景资料.我国南海海区第四纪孢粉藻类研究较差.本书系统研究了南海中北部及沿岸地区第四纪硅藻、孢粉组合,并借助计算机运算,应用因子分析、系统聚类、模糊聚类、对应分析等数理统计方法划带,恢复其硅藻植物群、孢粉植物群,探讨其演替和古气候、古环境变化,确定地层时代,进行地层划分与对比.本书系统研究了南海陆架和中部深海盆地表层沉积的硅藻、孢粉分布规律、组合特征及分区;探讨了孢粉组合、硅藻植物群的特点与环境的关系;南海北部陆缘热带、南亚热带第四纪植被带移动与古气候变化幅度;对结节圆筛藻壳体大小与古环境的相关性     

福建三沙湾表层沉积硅藻分布特征及其与环境因子的关系

通过对三沙湾24个站位表层沉积物样品进行硅藻分析,共鉴定硅藻31属84种（包括变种和变型）,其中夏季和冬季分别鉴定出31属71种和31属67种,主要属种以中心纲硅藻为主,如爱氏辐环藻（Actinocyclus ehrenbergii）、波状辐裥藻（Actinoptychus undulatus）、横滨盒形藻（Biddulphia grundleri）、中心圆筛藻（Coscinodiscus centralis）等.在生态习性上,底栖海水种占绝对优势.硅藻丰度从湾顶向湾外递减,夏季丰度高于冬季,平均丰度分别为9 003个/g和6477个/g.沉积物粒度分析显示,三沙湾表层沉积物以粉砂质粘土为主,研究表明三沙湾硅藻丰度与平均粒径存在一定相关性,夏季硅藻丰度变化范围为2 104～28 209个/g,粒径范围为5.26～7.36Φ,硅藻丰度与平均粒径变化范围都较大;而冬季硅藻丰度变化在1 929～14 372个/g之间,粒径范围为5.51～6.98Φ,相对夏季其变化较小,论证了水动力是影响硅藻沉积分布的一个重要因素.对影响三沙湾表层沉积硅藻分布的主要环境因子进行探讨,三沙湾表层沉积硅藻主要受潮流、深度和盐度等影响较大.     

末次冰期低纬度西太平洋硅藻席沉积与生态特征

硅藻在全球碳循环中发挥着重要的作用。"树荫种"硅藻在次表层水体中的勃发成席,并迅速埋藏成为硅藻席沉积,使人们逐渐意识到次表层生产在整个生产力及输出生产中起着重要作用。介绍了首次在低纬度西太平洋区域发现的硅藻席沉积的分布特征,硅藻席发现站位呈带状分布,大致呈北西-南东向展布,大部分散布在17.5°～20°N之间。采集到硅藻席沉积物的站位其水深在碳酸钙补偿深度(CCD)以下4837～6150m的深水区,多分布在较平坦的海底,且受风力和陆源物质输入影响相对较强的区域。该区域硅藻席的形成可能是由于末次冰期时该海区有大洋锋面的形成所致。该区域的成席硅藻Ethmodiscus rex(Wallich)Hendey为典型的"树荫种"硅藻,可以通过自身调节浮力的作用,在水体相对稳定的贫氧大洋中生存并勃发成席。末次冰期低纬度西太平洋硅藻席沉积的发生,可能使该区成为CO2的汇。     

2014年秋季渤海网采浮游植物群落结构

基于2014年秋季在渤海进行的水文、化学和生物方面的综合大面调查，研究了渤海网采浮游植物群落的结构特征，并结合文献资料，分析影响浮游植物群落结构形成的原因。结果显示:2014年渤海秋季共鉴定浮游植物3个门42属96种，其中以硅藻为主，为34属79种，占总物种的82%；甲藻门7属16种，占总物种的17%；金藻门1属1种。其中，角毛藻属的种类最多，共17种；其次为圆筛藻属，共13种。浮游植物总细胞丰度介于(0.71～72.15)×104 cells/m3，平均为13.88×104 cells/m3，硅藻与甲藻细胞丰度比值为2∶1，硅藻在莱州湾的细胞丰度极显著高于其他海区，甲藻在渤海中部海区的细胞丰度显著高于其他海区。浮游植物优势种主要为星脐圆筛藻(Coscinodiscus asteromphalus)、威氏圆筛藻(C. wailesii)、具槽帕拉藻(Paralia sulcata)、梭状角藻(Ceratium fusus)和夜光藻(Noctiluca scintillans)。渤海秋季浮游植物群落多样性水平分布不均，局部海域由于单一优势种过量繁殖多样性降低，低值区分布于辽东湾和渤海海峡海域。与历史同期资料对比，渤海海域浮游植物群落出现明显的物种演替现象，甲藻中的角藻逐渐兴起，其在渤海中部及辽东湾的优势地位已经超过角毛藻属和圆筛藻属，渤海秋季局部海区浮游植物群落结构已经由硅藻控制转为硅藻和甲藻共同控制。     

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.