渤海南部Lz908孔海陆交互沉积的粒度特征及其对沉积环境的指示

文章对采自莱州湾南岸的钻孔沉积物样品进行了粒度测试和分析。样品平均粒径介于3.3-6.8?,以极细砂和粗粉砂为主,含有少量的粘土质;分选较差;偏度表现为正偏和极正偏;沉积物粒度表现为正态、正态—尖锐和尖锐,少数表现为平坦和极尖锐。粒度象指示了历史时期持续高的初始沉积水动能和多种沉积环境的变化,粒度参数散点图反映了多种动能影响了沉积物的沉积改造,综合判别分析对沉积环境的限定,得到了莱州湾南岸沉积物受到河水径流、潮流、波浪等共同作用形成。沉积物总体反映了莱州湾南岸长时期处于河流相和三角洲相的沉积环境,少数较细的粒度表现可能与研究区的多期海侵过程相对应。     

渤海南部Lz908 孔海陆交互沉积的粒度特征及其对沉积环境的指示

对采自莱州湾南岸的钻孔沉积物样品进行了粒度测试和分析。样品平均粒径介于3.3Φ~6.8Φ,以极细砂和粗粉砂为主,含有少量的黏土质;分选较差;偏度表现为正偏和极正偏;沉积物粒度表现为正态、正态-尖锐和尖锐,少数表现为平坦和极尖锐。粒度象图指示了历史时期持续高的初始沉积水动能和多种沉积环境的变化,粒度参数散点图反映了多种动能影响了沉积物的沉积改造,综合判别分析对沉积环境的限定,得到了莱州湾南岸沉积物受到河水径流、潮流、波浪等共同作用形成。沉积物总体反映了莱州湾南岸长时期处于河流相和三角洲相的沉积环境,少数较细的粒度表现可能与研究区的多期海侵过程相对应。结果表明了粒度的综合分析对渤海南部的沉积环境有良好的辨识,是判断沉积环境的重要指标。     

南汇东滩沉积物粒度特征及其与水动力的关系

沉积物粒度参数可以用来反演沉积物沉积的水动力条件和沉积环境。根据对南汇边滩采集的表层沉积物粒度资料进行分析,结果表明:沉积物类型以黏土质粉砂为主;随着沉积物平均粒径Mz的减小,分选逐渐变好,偏态由极正偏向正偏转变,并向近对称接近。运用Pe- jurp的三角图式对沉积环境进行划分,结果表明南汇东滩的水动力条件总体上较强,沉积物粒径总体上偏粗,属于径流—潮流共同作用的河口浅滩沉积环境。对潮流底应力和沉积物临界起动切应力的计算进一步印证了该区水动力较强,对应沉积物颗粒偏粗的现象。     

日照近海表层沉积物粒度特征与沉积环境

对日照近海50个表层沉积物样品进行粒度计算、多元统计分析和沉积环境动力分区,结果表明研究区沉积物类型复杂,从泥质砂质砾到泥均有分布,共11种类型。沉积物粒度组成以砂和粉砂为主,砂含量占绝对优势,多以细砂形式存在。日照港和岚山港附近的沉积物粒径细,分选较差,负偏,峰态平坦,其它区域总体上粒径粗,分选差,正偏,峰态尖锐。研究区分为3个不同的沉积环境区。1区分布在傅疃河口近岸,为河口强动力沉积区;2区分布在东部15~20m水深区域,为潮流沉积和残留沉积混合作用区;3区分布在日照港和岚山港附近海域,为潮下低能沉积区。     

莱州湾西南部表层沉积物粒度分布特征及其现代沉积环境分区

根据莱州湾西南部207个表层沉积物样品的粒度分析结果,对莱州湾西南部沉积物粒度分布特征进行了研究,在此基础上应用系统聚类分析方法并结合物源及水动力条件探讨了其现代沉积环境分区。结果表明,研究区表层沉积物类型以粉砂质砂、砂质粉砂和粉砂为主,分布范围最广的粉砂主要位于淄脉沟以北;沉积物平均粒径由近岸向莱州湾中部逐渐变细,从南向北呈现粗—细—粗的变化趋势;研究区现代沉积环境分为高能粉砂质砂粗粒沉积区、砂质粉砂过渡沉积区以及低能粉砂细粒沉积区,其水动力环境表现为波浪作用逐渐减弱,潮流作用逐渐增强,沉积物物源由近岸河流、岸滩侵蚀来沙为主变为以黄河悬浮—再悬浮物质为主。     

金州湾表层沉积物粒度特征及沉积环境

通过对金州湾海域72个表层沉积物样品进行粒度分析,探讨了金州湾表层沉积物物质组成和粒度参数的分布特征,根据粒度参数特征,利用Q型聚类分析将研究区划分为3组沉积区,结合粒度频率分布曲线、粒度概率累积曲线和C-M图阐述沉积物的粒径组成、沉积动力条件和沉积物的搬运沉积条件。结果表明：研究区沉积物类型为粘土质粉砂、粉砂质砂、砂质粉砂、砂和砂 粉砂 粘土。研究区可划分为3种沉积环境,Ⅰ组沉积环境：沉积物类型以砂质粉砂和粘土质粉砂为主,粒径较小,含部分粗组分颗粒物,分选差,粒度频率分布曲线呈双峰,形成较为封闭静稳的海湾环境;Ⅱ组沉积环境：沉积物类型以粘土质粉砂为主,粒径小、分选较差 差,沉积环境较为复杂,为受潮流和沿岸流作用的沉积环境;Ⅲ组沉积环境：沉积物类型以粉砂质砂和砂为主,粒径较大、分选较差,为受潮流和海流影响的沉积环境。整体上由东向西,沉积物呈现出细 较粗 粗的变化趋势。其原因在于机场人工岛的建设阻挡了潮流和海流的作用,导致东部的I、Ⅱ组沉积环境形成较为封闭的环境;Ⅲ组沉积环境为离岸较远的海洋环境,水动力较强,海洋性特征明显。因此机场人工岛的建设对金州湾海域沉积物的分布产生了显著影响。     

湛江红树林保护区现代沉积物粒度特征及其对风暴事件的响应

沉积物粒度是描述沉积环境的重要指标之一,利用沉积物粒度参数可以反演沉积物堆积过程、沉积水动力特征.通过对湛江红树林国家级自然保护内海湾、河口、潮坪区的红树林表层沉积物粒度分析的研究,结果表明：河口与海湾区的红树林沉积物以泥质为主;有堤坝保护的河口区红树林沉积物颗粒细,为悬移质体含量高且连续稳定的低能环境;红树林发育差的潮坪区红树林沉积物为砂含量较大且水动力较强的高能环境.并通过推算海湾区沉积物的沉积年代,结合样品粒度分析的结果得出了该地区风暴潮发生的大致时间.     

现代黄河三角洲表层沉积物的空间分布特征

基于近期在黄河三角洲附近海域采集的97个表层沉积物样品的粒度测试结果,研究了黄河三角洲海域表层沉积物的类型和空间分布特征,探讨了沉积物粒度分布特征与物源和沉积动力环境之间的关系。研究结果表明,研究区表层沉积物类型以砂质粉砂和粉砂为主,在绝大部分海域,表层沉积物的偏态表现为正偏和极正偏,分选程度较差,峰态表现为宽和很宽。现行河口三角洲叶瓣周围的表层沉积物以砂质粉砂为主,粒度较粗;而在远离河口的区域表层沉积物以粉砂为主,粒度较细。与20世纪80年代的观测结果相比,受物源供应和沉积环境的共同影响,近期黄河三角洲沿岸的表层沉积物有粗化的趋势,且河口口门区域表层沉积物粗化趋势最为明显。表层沉积物粒度粗化的主要原因是黄河入海泥沙供应不足,导致三角洲沿岸侵蚀加剧;黄河调水调沙以来入海泥沙的粒度变粗,粗颗粒组分在河口口门附近快速堆积。黄河水下三角洲现代沉积速率的分布特征表明,黄河入海沉积物主要在现行河口及三角洲的近岸区域沉积,在15m以深的区域沉积速率较低。同时,还可看出入海泥沙有向北和东北向的运移趋势,与渤海中部泥质沉积以及通过莱州湾向渤海海峡的泥沙输运相对应。粗颗粒沉积物在现行河口三角洲叶瓣的堆积范围与潮流切变锋的位置基本一致,反映了物源供应和沉积动力环境对研究区表层沉积物分布特征的控制性影响。     

海南岛东南浅海表层沉积物粒度特征及沉积环境

对海南岛东南浅海377组表层沉积物样品(平均水深112.3 m)开展粒度测定及沉积物类型划分,并运用统计规律及沉积输运趋势分析,探讨了底质沉积物分布格局与物质来源及沉积动力环境关系。结果表明,海南岛东南浅海沉积物类型复杂,共分布13种沉积物类型,粒度组成以粉砂和砂为主,平均粒径均值为5.73Φ,优势粒级为细粉砂级(6~8Φ),分选差。不同海域沉积物粒径差异明显,北部近岸以含砾沉积为主,中部呈NE-SW向的砂质沉积区(水深80~120 m),西南近岸滨海、北中部海域以及东南部海域多为粉砂、黏土沉积。结合地理位置、沉积物源及水动力条件差异,研究区划分为3个沉积区:I区主要以含砾粗颗粒沉积为主,受控于海南岛上径流及强风浪作用,物质来源以万泉河等河流输运及岸线侵蚀物质为主,强动力(高能)沉积环境;II区以砂沉积为主,受到表层流及风浪等共同影响,可能主要是残留滨海沉积混入了海南岛径流及岸线侵蚀、少量珠江流域及外海复杂来源等现代细粒物质的混合沉积,中等动力沉积环境;III区以细粒沉积为主,主要受华南近岸流、风浪作用及南海暖流影响,推测物质来源主要为海南岛河流输入、岸线侵蚀及复杂外海来源细粒物质的加入,弱动力(低能)沉积环境。     

南海北部陆架区表层沉积物粒度特征与沉积环境

对南海北部陆架沉积区244个表层沉积物样品进行了粒度组分、多元统计及输运趋势分析,结果表明:南海北部陆架区共分布9种沉积物类型,粒度组成以砂和粉砂为主,砂含量占绝对优势,沉积物主要粒级为0~8Φ,优势粒级为0~4Φ。研究区东北部粒径较粗,以中砂为主,分选中等-好,负偏,峰态中等-平坦,西南部粒径较细,以粉砂为主,分选较差,正偏,峰态平坦,中间过渡及陆架外缘粒径中等,以细砂为主,分选中等,正偏,峰态尖锐。基于粒度多元统计及输运趋势分析,南海北部陆架划分为3个沉积区:珠江口及粤东近岸沉积区(I区):主要受控于沿岸流,水动力条件较弱,物质来源以珠江、韩江等河流输运物质及近岸基岩风化、岛屿剥蚀作用产物为主,少量东沙群岛海底冲刷剥蚀产物;混合过渡沉积区(II区):受黑潮南海分支、南海暖流及沿岸流共同作用,水动力条件中等,物源复杂多样,为珠江携带陆源物质、台湾浅滩物质以及东沙群岛附近海底剥蚀产物的混合沉积区域;台湾浅滩及珠江古三角洲残留沉积区(III区):受黑潮南海分支、南海暖流、北部九龙江、沿岸流等影响,海洋水动力条件较强,以晚更新世的残留沉积为主,同时可能接受了少量现代沉积物质。     

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.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

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。     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

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.     

《Acta Oceanologica Sinica》Vol. 33(2014) contents

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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,