河口生态需水研究进展

针对陆海交互作用下河口生态需水影响因素多且时空差异性显著的特点,在系统分析淡水输入对河口生态系统水环境过程和生物过程影响的基础上,按生态需水目标的差异,将河口生态需水分析方法划分为基于典型生物资源保护目标、基于生境保护目标以及基于多目标整合分析3种类型。从生态需水目标筛选、生态需水目标对淡水输入响应关系以及生态需水计算方法实用性方面探讨了河口生态需水研究中面临的主要问题。结论认为生态系统健康综合表征指标的确定应成为分析河口生态需水的关键科学基础,筛选控制性生态要素构建河口关键生态水文过程模型可成为有效提高生态需水计算方法实用性的主要技术手段。     

河口观測与研究

一、河口河流注入海洋,其汇合之处,是謂河口。在河流注入海洋的地方,經常有大量的泥沙沉积,在这种情况下就造成了多(氵义)河的河口,因为它們在平面圖上很象三角形,所以称为三角洲;如珠江河口。河流挾带的泥沙愈少三角洲的形状就愈不显著,强大的潮汐和海浪常破坏三角洲的形成,在这种情况下,河流往往     

珠江河口沉积物粒度特征及其对底层水动力环境的指示

珠江口伶仃洋及邻近海域沉积物粒级变化大。频率分布曲线形态的变化揭示了珠江河口不同区域泥沙来源的差异。在平面分布上,粗粒级含量从西北部和北部向东南部迅速降低,而细粒级含量高值往往出现在河口中部。表层沉积物平均粒径梯度变化方向与珠江口悬浮物的运移方向大致吻合。反演获得的底层海流不同区域的优势速度与实测资料相符。两者较好地指示了沉积物多年平均优势海流速度和方向,表明利用沉积物粒度数据比较成功地反演出了珠江口沉积物推积前的搬运水动力环境。     

瓯江河口生境破碎化研究

瓯江河口沿岸与外海水交汇地区,是海洋无脊椎动物、鱼类栖息、索饵产卵和生长的优良场所,由于围垦造地、航道整治已缩小了鸟类和海洋生物的栖息地。人类活动对河口地区栖息地的影响可通过生境破碎化研究来确定其扰动程度。根据瓯江河口海域测站相关的水环境因子,通过聚类分析方法对瓯江河口水生境破碎化进行定性分析,结果表明瓯江干流虽被七都涂和灵昆岛分流后水流流态发生改变和流量、泥沙分配不均,使得其水生境斑块与瓯江干流生境存在差异,但总体水生境斑块还是处于连续状态;瓯江河口附近的海域水体理化特征呈高度异质性,斑块状分布特征明显。再通过各生境因子的生境斑块类型图分析瓯江海域水体原来较大斑块的自然水体景观被分割情况,确定瓯江河口水生境破碎化程度。     

珠江河口夏季缺氧现象的模拟

夏季底层水体缺氧现象是珠江河口存在的环境问题之一。使用三维水动力-生态耦合模型来分析珠江口缺氧现象的分布状况和产生原因。模拟结果表明:模型能很好的再现珠江口的缺氧敏感性区域和强度。珠江口存在的底层水体缺氧现象是水体强烈层化和生化耗氧过程共同作用的结果。缺氧现象的发展与减退受潮汐涨落的影响。珠江口盐度-潮汐混合锋面和层化作用控制低氧水团的范围和强度。     

生态模型在河口管理中的应用研究综述

河口作为河流和海洋的交汇地,具有生态交错带特性,其在自然和人类活动双重压力下发生着演变.生态模型是研究生态系统结构、功能及其时空演变规律以及生物过程对于生态系统的影响及其反馈机制的重要手段.采用不同方法对生态模型进行分类,综述各类生态模型的特性、优缺点及应用领域.讨论建模过程中模型变量与函数、模型整合及时空尺度、模型参数取值及不确定等关键技术问题.分析各类生态模型在河口生态工程设计、生态系统修复、生态系统评价、系统决策支持等管理领域的应用.尽管中国河口生态模型构建及应用已有一些成果,但与国外相比,在理论生态学及数据积累方面仍有一定差距.     

长江河口和密西西比河河口水文测验工作比较

长江是我国第一大河,密西西比河是美国第一大河流,两条河流在许多方面都有相似的地方。本文首先对两大河口进行了简介,并对国内外河口测验现状进行了介绍,继而从站网分布、测验整编、数据的传输、体制和管理、经费来源和服务关系等方面对长江河口和密西西比河河口进行了比较分析,进一步深入分析原因及其形成根源,最后为长江河口水文发展提出建议与借鉴。     

河口海岸桥隧工程设计流速推算

跨海桥隧工程设计需要推算工程位置不同重现期设计流速,由于现场缺乏长期实测流速资料,设计流速推算存在很大困难。研究提出了采用不同重现期典型风暴潮过程推算河口海岸设计流速的数值模拟方法,对河口地区考虑洪水径流与风暴潮流的耦合。在依据澳门验潮站1925—2003年实测潮位资料分析珠江口海域风暴潮过程特征的基础上,结合潮位和潮差年极值频率分析结果构建了不同重现期典型风暴潮潮型。采用平面二维水动力数学模型模拟了不同重现期风暴潮和上游一般洪水组合条件下珠江口水域的流场,得出港珠澳大桥沿线各控制点处设计流速。     

珠江澳门河口沉积物柱样品正构烷烃研究

报道了珠江澳门河口沉积物柱芯榈中正构烷烃的浓度和分布类型,并通过因子分析方法对正构烷烃的来源加以初步探讨。沉积物柱芯样品于１９９７年３月采自珠江澳门河口区,沉积年龄以＾２１０Ｐｂ法稳恒初始放射性模式（ＣＡ模式）测定。样品中的有机污染物以二氯甲烷／丙酮混合溶剂索氏提取后,正构烷烃组分以ＧＣ／ＭＳＤ定量分析测定。研究结果表明,该现代沉积物桩芯样品沉积时间约历时４０ａ,桩芯样品中正构烷烃的含量范围为０．     

国外河口表面锋机制研究概述

回顾了国外河口锋面研究的最新成果,阐述了河口羽状锋、河口潮汐混合锋和河口切变锋的动力机制.河口羽状锋的机制研究以Garvine等人的观点最为特出.河口潮汐混合锋是由河口垂向环流中水体密度梯度所引起.河口切变锋是由滩槽流速切变引起的.     

Driving forces and management strategies for estuaries in northern China

Estuaries, which lie at the end of rivers, belong to the interlocking area between marine ecosystems and terrestrial ecosystems. In the estuary region, there are plenty of biological resources that carry many important ecosystem services. However, severe degradation of the estuary ecosystem in northern China has been caused by anthropogenic disturbances, including water pollution from upstream area, change of marine environmental dynamics, animal habitat loss, and unreasonable exploitation in the estuary region. In order to provide scientific evidence for restoration and conservation of the estuary ecosystem, we collected data from published literature to analyze the ecological problems in several main estuary regions in northern China, such as the Yellow River estuary, Liaohe River estuary, Haihe River estuary, Yalu River estuary, and some others. The main ecological problems in the estuary region of northern China include the input decrease of fresh water from rivers, the change of the sediment input from rivers, the destruction of the estuary wetland ecosystem, the environmental pollution in the estuary region, the erosion in the estuary region, seawater encroachment, the biodiversity decline of the estuary region, and the depletion of the fish resources in the estuary region. Meanwhile, the driving forces for these ecological problems in the estuary region were also assessed. Based on the analysis of these driving forces, we propose several pieces of advice for integrated estuary management in northern China, including the creation of a management system for estuary conservation, improvement of the means and strength of the environmental law execution, increased investment on scientific research in the estuary ecosystem, improvement of public participation on the conservation for the estuary environment and biodiversity, and construction of a monitoring system for the estuary environment.     

Water column light attenuation estimation to simulate phytoplankton population in tidal estuary

The penetration of sunlight into the water column plays a critical role in the aquatic ecosystem. The irradiance available for primary production in a water body depends on the incident light at the water surface, light extinction in the water column, and depth. In this study, the light attenuation through the water column of the Danshuei River–Keelung River estuary was estimated. The measurement of photosynthetically active radiation (PAR) indicates that the conventional exponential attenuation of light with depth is a very good model. A light attenuation coefficient may be derived from the PAR measurements at each location. The regression with salinity yields a good correlation, indicating that the fraction of seawater should be a good parameter for estimating the water column light attenuation coefficient (K _d ). A laterally averaged two-dimensional finite difference model for hydrodynamic and water quality model was performed and applied to simulate the phytoplankton population at the lower reach of the Danshuei River estuary. In the process of phytoplankton population simulation, the regression model of K _d and salinity was incorporated in the water quality model. The simulated results show that the modeled concentration of chlorophyll a matched the measured values at the lower reach of the Danshuei River estuary.     

Heavy metals in sediments of the rhine and elbe estuaries: Mobilization or mixing effect?

On their way from the Rhine estuary into the North Sea and Dutch Wadden Sea, Rhine sediments “lose” large portions of their original heavy metal concentrations. Until now these losses were explained by a mobilization process, solubilization — the decomposition products of organic matter form soluble organometallic complexes with the metals of the sediment. Our investigations of the sediments of the Elbe clearly indicate that a mixing process, whereby highly polluted Elbe sediments mix with relatively non-polluted North Sea sediments, rather than solubilization, is the cause of the dilution of heavy metals in the sediments of the Elbe estuary. Because of the similarity of the Elbe data with those from the Rhine River, we propose that a mixing process is also effective in the Rhine estuary and adjacent North Sea areas. The mechanism by which heavy metals are “diluted” is important to the marine ecosystem. In the mixing process proposed in this paper, the heavy metals fixed to the suspected material are trapped in bottom sediments of the marine environment, whereas solubilization would increase the concentration of heavy metals in the sea water and thus they would be more available for uptake by aquatic organisms.     

珠江口表层沉积物的重矿物分析

本文研究了珠江口表层沉积物中约200个样品的矿物,着重分析重矿物的组合、含量变化,形态特征等,把珠江口重矿物的平面分布划为五个重矿物区。指出珠江口为现代陆源物质充填的河口湾,沉积环境控制了重矿物的特征、分布及分区,重矿物沉积过程的规律性,可供寻找地质时期和现代的浅海(古滨海)砂矿借鉴。     

Heavy metal distribution in sediment profiles of the Pearl River estuary,South China

The Pearl River estuary is created by the inflow of freshwater from the largest river system that drains into the South China Sea. In recent years, massive economic growth and development in the region has led to excessive release of waste into the environment. The accumulation of contaminants in sediments is likely to pose serious environmental problems in surrounding areas. The study of sediment profiles can provide much information on the metal contamination history and long term potential environmental impacts. In this project, 21 core samples (up to 3.65 m deep) were collected in the Pearl River estuary. About 15 subsamples from each core were analysed for moisture content, total organic matter (L.O.I.), particle size and heavy metal and major element concentrations. The results show that Pb and Zn contents are elevated in the sediments at most of the sampling sites. Compared with historical monitoring results, the sediment metal contents have increased over the last 20 a, particularly for Pb. The west side of the Pearl River estuary tends to be more contaminated than the east side due to the contaminants inputs from the major tributaries and different sedimentation conditions. There are close associations between Fe, Co, Ni and Cu concentrations in the sediments. Zinc and Pb contents in the sediment profiles reflect a combination of the natural geochemical background, anthropogenic influences and the mixing effects within the estuary. The distribution of Pb in the sediments shows strong influences of atmospheric inputs, probably from the coal burning activities in the region.     

黄河三角洲海岸带陆海相互作用概念模式

根据陆海相互作用的观点,黄河流域、黄河干流、河口三角洲及其邻近海区的生态环境相互联系,组成了一个有机的生态系统链,可称为黄河-渤海生态系统。黄河流域的降水量、土壤植被条件使黄河干流具有水少沙多、水沙异源和水资源缺乏的特征。干流入海水、沙通量变化影响了黄河三角洲地区的侵蚀、堆积和发育过程。黄河物质入海后在河口及邻近海域形成了具有高生产力的生态环境和著名的渔场。据此绘出了黄河-渤海生态环境内各环节相互联系的概念模式图,并提出了黄河流域大面积水土保持和南水北调工程逐步展开等新环境下,本区陆海相互作用的研究方向。     

珠江三角洲水资源可持续利用综合评价分析

按照复合系统理论。水资源可持续利用系统是一个由水资源、社会经济和环境等子系统组成的复合系统．且各子系统包含多个要素。由此，本文构建珠江三角洲水资源可持续利用评价层次结构多指标体系．采用主成分分析法和层次分析法对珠江三角洲水资源可持续利用进行综合评价，评价结果客观地反映了珠江三角洲各地区的水资源可持续利用状况。在评价结果的基础上，对珠江三角洲各地区的水资源可持续利用问题提出了相应的建议。     

珠江口黄茅海河口湾表层沉积物中有孔虫和介形虫的分布及其影响因素*

珠江口黄茅海河口湾的表层沉积物100个站位样品中共发现有孔虫21属36种、介形虫16属20种。优势种组合分别为Ammonia beccarii-Quinqueloculina akneriana rotunda-Cavarotalia annectens-Elphidium advenum和Neomonoceratina delicata-Sinocytheridea impressa-Bicornucythere bisanensis。有孔虫及介形虫的丰度和分异度均表现出“北低南高”,即口门低、向海高的特点。样品中有孔虫和介形虫属种的去趋势对应分析（DCA）表明,盐度是影响该区有孔虫和介形虫分布的最重要因素,其次是水动力条件,水深对有孔虫和介形虫的分布也有一定影响,但并非主要控制性因素。由于受径流影响较大,河口湾北部的水体盐度较低、径流动力较强,不利于有孔虫和介形虫的生存,导致其丰度及分异度均较低。河口湾南部水体盐度升高,潮流动力较强,同时受众多岛屿屏障作用,环境较为稳定,有孔虫和介形虫的丰度和分异度均迅速上升。     

基于联合分布的珠江口设计潮位过程线方法研究

针对同倍比方法与同频率方法推求设计潮位过程线中的局限性,采用4种边际分布函数对珠江口年最高潮位与年最大潮差序列进行拟合的基础上,选取4种不同的二维Archimedean Copula函数建立珠江口年最高潮位与年最大潮差的联合分布,并分析了高潮位重现期与潮位过程同现重现期的线性关系。结果表明:高潮位与潮差的同现重现期总是大于相应边际分布的重现期,并且随着边际分布重现期的增大,同现重现期增幅也越大,说明较高重现期的高潮位与潮差同时发生的可能性很小;基于高潮位重现期与潮位过程同现重现期的线性关系,采用基于联合分布的方法推求珠江口潮位过程线,推求结果较同频率法更为合理。     

珠江口地区岩土层工程地质特征及物理力学性质研究

基于港珠澳大桥、深中通道、虎门大桥等工程的精细化勘察成果,分析了珠江口地区岩土层地质特性,区内岩土层可划分为淤泥质软土层、黏土粉质黏土层、中粗砂层、残积土层、不同程度风化基岩共5大层,结合区内水动力环境、沉积物类型、钻孔对比及地质剖面,将研究区划分为河口砂质沉积区、潮流型泥质沉积区、泥砂混合沉积区、浅海泥砂混合沉积区等4类。珠江口地区岩土层的物性参数特征研究表明,随着深度增大,岩土层含水率降低,快剪黏聚力增大,压缩系数减小,压缩模量增大;原状土十字板抗剪强度C_u与软土含水率w呈幂函数相关,与压缩模量E_s、快剪黏聚力c呈线性正相关;孔压静力触探试验比贯入阻力p_s与含水率w呈对数相关,与压缩系数a_1?2呈幂函数相关,与黏性土、砂类土的快剪黏聚力c呈线性正相关,得到的经验公式可为珠江口地区类似场地工程建设提供参考。