冲绳海槽北部表层沉积物中浮游有孔虫的分布与海洋环境

为查明冲绳海槽北部浮游有孔虫动物群的分布特征与海洋环境之间的关系，对1992年6月和1999年6月两次采白冲绳海槽北部111个表层沉积物中的浮游有孔虫进行了鉴定和统计，并利用Q型因子分析方法对其群落组合特征进行了分析。结果表明，冲绳海槽北部浮游有孔虫主要有3个因子组合。以Globlobigerinita glutinata(Egger)为代表的主因子1主要分布在东南侧的黑潮主干和对马暖流控制区内，同时受西侧陆架冷水影响的部分站位也显示了较高的载荷值。G．glutinata的种群特征显示，黑潮主干和对马暖流控制区以大个体分子为主，而小个体分子主要集中在受冷水影响的陆架浅水区。因此，G．glutinata很可能是300N以北海域黑潮及其分支流系的优势种，而其小个体分子在陆架浅水的存在可能与东海冷涡沉积动力环境相关。以浅生种Globigerinoides ruber(d‘Orbigny)为代表的主因子2主要分布在研究区西侧和北侧水深100—150m之间的陆架浅水区。以Neogloboquadrina dutertrei(d’Orbigny)和Pulleniatina obliquiloculata(Parker＆Jones)为代表的主因子3，主要分布在研究区中部的黑潮和对马暖流与陆架水的混合区内。因此，冲绳海槽北部浮游有孔虫动物群的分布受到海流、水团、水深等多种海洋环境因素的影响。     

白令海和楚科奇海表层沉积中的有孔虫及其沉积环境

通过对白令海和北冰洋楚科奇海39个表层沉积样品中有孔虫的定量分析,发现表层沉积中浮游有孔虫稀少可能与该区表层生产力低、碳酸盐溶解作用较强有关,而底栖有孔虫的分布则主要受表层初级生产力以及与水深相关的碳酸盐溶解作用和水团性质所控制,其中北冰洋楚科奇海陆架区有孔虫以Elphidium spp.组合和Nonionella robusta组合为主,丰度和分异度低,受北冰洋沿岸水团控制;白令海陆坡区有孔虫以Uvigerina peregrina-Globobulimina affinis组合为主,含N.robusta较多,丰度和分异度相对高,受太平洋中层和深层水团控制,但该区碳酸盐溶跃层和补偿深度(CCD)相对浅,约分别位于2000和3800m处.此外,白令海陆坡上部表层沉积中含有北冰洋陆坡区典型深水底栖有孔虫种Stetsonia arctica,说明白令海峡两侧的海区曾有深部水交流.     

南海东沙海域HD319岩心富甲烷环境底栖有孔虫群落结构

对南海东北部东沙海域HD319岩心富甲烷环境和非富甲烷环境底栖有孔虫进行对比研究,旨在探讨富甲烷环境对底栖有孔虫群落结构的影响。结果表明,该岩心富甲烷环境和非富甲烷环境的底栖有孔虫组成有所差异:富甲烷缺氧环境底栖有孔虫群落中耐低氧类内生种群占绝对优势,Uvigerina(U.peregerina,U.hispido-costata,U.rugosa,U.probscidea,U.spp.),Bulimina(B.aculeata,B.mexicana),Bolivina(B.bradyi,B.quad-rilatera),Globocassidulina subglobosa,Brizalina superba,Hoglundina elegans等冷泉甲烷相关种大量出现;非富甲烷一般低氧环境下底栖有孔虫以内生种含量占优势,表生种和旋向种零星出现;富氧环境下底栖有孔虫以表生种和旋向种占优势,受有机碳含量变化控制明显。推测底栖有孔虫这种群落结构的差异是适应高甲烷含量的结果,底栖有孔虫对富甲烷环境的响应通过群落结构的差异表现出来。     

早第四纪西太平洋底栖有孔虫群与大洋深层水环流演化的关系

选取赤道西太平洋ODP 807站位(3°36.42′N,156°37.49′E,水深2 803.8m,岩心长822.9m)26.27～43.02mbsf层段中的底栖有孔虫进行研究,以便了解早更新世2.5～1.6Ma BP时期古生产力和深水环流的变化。结果显示,这一时期底栖有孔虫堆积速率(BFAR)、表生种和内生种比值(E/I)、Uvigerina spp.百分含量和有机碳百分含量(TOC%)等替代指标反映了西太平洋古生产力总体上呈现冰期高、间冰期低的特点,而其中Bulimina alazanensis的丰度变化则相反,反映了该种有可能更适合温暖、低营养的底层水环境。2.5～1.6 MaBP时期底栖有孔虫在丰度上以Uvigerina spp.为主,指示了早更新世西太平洋深层水受北部水团的控制更强。     

南海西部MIS3期底栖有孔虫反映的生产力变化

选取位于南海西部越南岸外上升流区的17954-2沉积柱状样为研究对象,通过对底栖有孔虫属种含量变化的分析,并与该站位已有的有孔虫研究结果对比,获得该海区MIS 3时期海洋古生产力的变化记录.结果表明,柱状样中的底栖有孔虫堆积速率和指示生产力的底栖有孔虫属种(Bulimina aculeata,Uvigerina per...     

长江远端三角洲表层沉积物中底栖有孔虫分布及其对环境的指示

长江远端三角洲是东海内陆架泥质沉积体重要组成部分,是全新世高海平面时期以来形成的重要地貌单元,其包含了高分辨率沉积环境与气候变化信息,对该地区现代沉积环境及其影响条件的分析将有助于长时间尺度古记录识别与反演。对研究区海域145个站位的表层沉积物样品进行了底栖有孔虫化石分析,鉴定结果表明该地区底栖有孔虫有52种,以玻璃壳体类型为主,平均含量占底栖有孔虫总量的90.6%,其次为瓷质壳,胶结壳含量最低。进一步因子分析结果表明,研究区底栖有孔虫可划分为4个组合:组合Ⅰ(Ammonia beccarii vars.-Quinqueloculina spp.)分布在研究区西部近岸浅水区,组合Ⅱ(Bolivina robusta-Bulimina marginata-Hanzawaiaspp.)分布于研究区东南部水深较大处,组合Ⅲ(Elphidium hispidulum-Fursenkoina schreibersiana)呈带状分布于近岸,组合Ⅳ(Elphidium advenum-Ammonia pauciloculata)分布区域位于组合Ⅰ和组合Ⅱ之间。组合Ⅰ可能指示区域水体环境受闽浙沿岸水团影响;组合Ⅱ可能指示区域水体环境受台湾暖流水团影响;组合Ⅲ的分布可能与夏季闽江水与外海水混合发生水体层化有关;组合Ⅳ可能指示区域水体环境受季节性闽浙沿岸水与台湾暖流水团影响。     

南海巽他陆坡晚更新世以来的微体化石和古环境

柱状样 182 88- 2采自于南海南部巽他陆坡 (5°4 4′N、 110°4 4′E,水深 788m ,柱长 6 .8m ) ,通过与邻近柱状样同位素的对比 ,其揭示了末次冰盛期以来的沉积。柱状样中指示水深较大的介形类和浮游有孔虫丰度自下而上呈现明显增加的趋势 ,而指示水深较浅的介形类丰度及介形虫 /浮游有孔虫比值和底栖有孔虫在有孔虫全群中的丰度都呈下降趋势 ,反映了研究区末次冰盛期以来海面上升和海水加深的过程。这两类的变化在 YD至全新世早期最为显著 ,与该时期海面快速上升造成的环境急剧变化相对应。异地介形虫广见于末次冰期和全新世早期的沉积中 ,反映冰期低海面和冰后期海侵初期频繁发生源于陆架的顺坡搬运。依据末次冰期沉积中含较多的底栖有孔虫 Uvigerina和 Bulimina、介形虫 Polycope和 Cytherella,及底栖有孔虫 U.peregrina较低的δ1 3C,推测冰期低海面时底层水状况为低氧和高营养 ,在冰盛期尤为发育     

冲绳海槽南部两万年来碳酸盐溶跃面的变迁

对冲绳海槽南部表层沉积和晚第四纪沉积柱状样中百余个样品进行了浮游及底栖有孔虫、翼足类等微体化石定量分析。通过表层沉积样品中底栖有孔虫占有孔虫全群比例、底栖有孔虫群中胶结质壳比例、浮游有孔虫碎壳率和浮游及底栖有孔虫丰度等多种标志的水深变化,确定冲绳海槽现代的碳酸盐溶跃面位于水深１５００～１６００ｍ处。进而,在高分辨率地层学基础上,检验这些指示溶解作用的标志和翼足类丰度等在柱状样中的变化,结果发现末次冰期冲绳海槽碳酸盐溶解作用显著减弱,碳酸盐溶跃面和文石补偿深度急剧变深;至冰后期碳酸盐溶解作用又急剧增强,溶跃面和文石补偿深度又变浅至与现代相当的位置。这些变化与南海等西太平洋其他海区的特征相一致。     

东沙西南海域表层底栖有孔虫碳同位素对冷泉活动的指示

底栖有孔虫碳同位素负偏记录是冷泉活动的重要指标之一。对南海北部东沙西南海域4个含碳酸盐结核的表层沉积物样品中的6种底栖有孔虫进行了氧碳同位素分析,结果表明,表生属种Discanomalina semiungulata、Cibicides wullerstorfi、Cibicides pseudoungerianus、Cibicides lobatulus的碳同位素,相对同水深南海现代表生底栖有孔虫有明显的负偏记录,尤其是表生种D.semiungulata基本都偏负;内生种Lenticulina orbicularis也有部分负偏,而Uvigerina auberiana的碳同位素则明显偏正;几种底栖有孔虫的碳同位素波动幅度都明显较大,明显超出了南海最近两个冰期-间冰期旋回中碳同位素的变化幅度。其中生活在蠕虫管壁上的活体底栖有孔虫D.semi-ungulata和C.lobatulus的同位素都呈明显的负偏,认为该区底栖有孔虫碳同位素这种负偏和波动幅度大可能是由于冷泉活动造成的。活体底栖有孔虫碳同位素负偏表明该区可能存在有正在活动的冷泉,其中表生种D.semiungulata的大量出现可以作为南海冷泉活动的一个潜在指示标志。     

台湾海峡西北部表层沉积物中有孔虫分布对沿岸上升流存在的响应

对台湾海峡西北部福建平潭岛附近海域337个表层沉积物样品中的有孔虫进行分析鉴定,研究结果表明浮游有孔虫优势种Globigerinoides sacculifer、G.ruber、Globigerina bulloides的分布及底栖有孔虫组合受到不同水团的影响。根据浮游有孔虫上升流指示种G.bulloides、底栖有孔虫组合和高营养盐深水种的分布特征,对研究区受夏季沿岸上升流的影响范围和程度进行评估。研究区沿岸上升流主要分布于东南部水深大于40m的海域及平潭岛东部水深20m附近,最远可达水深低于10m的海湾内部分区域,但强度相对减弱,水深较浅的陆地和岛屿边缘附近未受沿岸上升流影响。平潭岛东北部到南日岛西南部水深10~30m部分区域由于受到冬季浙闽沿岸流的影响,沿岸上升流在该区域的沉积记录缺失。     

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.     

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,     

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.     

Net Sand Transport Direction in a Tidal Inlet, using Foraminiferal Tests as Natural Tracers

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.