Hydrocarbon pollution from marinas in estuarine sediments

A measure of the impact of marinas on three Eastern Virginia estuarine creeks was obtained by a study of hydrocarbons in their sediments. Two of the creeks support considerable marine activity, including pleasure boat marinas, boat repair facilities, and commercial fishing operations. The third creek, which served as a control, is seldom used by boats, and is surrounded by marsh and woodland.Sediments from the creeks with marinas contained significantly higher levels of both aromatic and aliphatic hydrocarbons than did the control. Differences in the concentrations of certain oil-pollution indicators, such as the 17α,21β-hopane homologs and phytane, and low molecular weight aromatic hydrocarbons, are indicative of light petroleum fractions. Most of the aromatic hydrocarbons from all creeks, however, appear to have a pyrogenic origin.Although hydrocarbons from three probable origins (petroleum, pyrogenesis, and recent biosynthesis) were detected in all locations, the petroleum-derived and pyrogenic hydrocarbons were of only minor importance relative to the biogenic hydrocarbons in the control creek.     

Mediterranean pollution: Health related aspects

Starting from the premise that the main Mediterranean pollution problems are all directly or indirectly health-related, this article surveys the health components of the Mediterranean Action Plan. The Action Plan's pilot projects are described and problems of coordinating national scientific methodologies are pointed out. The protocol on landbased pollution and the problem of mercury in seafood are analysed. The article concludes that, while there is no room for complacency, the extent of Mediterranean pollution has been exaggerated by some commentators.     

Hydrocarbon gases in sediments and mud breccia from the central and eastern part of the Mediterranean Ridge

 Microbiologically produced hydrocarbon gases (HCGs) in normal pelagic sediments have lithologically controlled distribution – their content increases sharply in organic-rich sapropels. Generally, the HCG content is low (<10000 nl/l), The amount of heavy HCGs is high (up to 60%, unsaturated HCGs dominate the saturated ones, and ethylene is prevalent. The same features were found in sediment and mud breccia from inactive mud volcanoes. Thermogenic HCG was determined in active mud volcanoes and in a high salinity fluid vent. They are characterized by: high methane concentration, δ¹³C(CH₄) =−37.1 to −57.8%, essential ethane contents (2–7%), absence of unsaturated HCG, and the prevalence of iso-over n-butane.     

海岸线长度量算方法的研究

海岸线是重要而宝贵的自然资源,准确量算海岸线长度是摸清海洋家底和实施有效管理的前提.但目前海洋界没有统一的海岸线长度量算方法.提出基于高斯平均引数的椭球面长度算法,并采用MapBasic语言的实现海岸线长度的自动化计算,通过验证和比对,比目前海洋界普遍采用的平面长度算法更准确,可在实际工作中推广.     

现代海岸线划定方法研究

我国把海岸线定义为"平均大潮高潮时海陆分界的痕迹线",其长度以1∶50 000比例尺精度量算.但这条划分海陆的地理环境界线绝大部分时间是裸露的,1个月内海水可以到达的时间也仅有2～3 h.人们为什么不以海水浸淹和裸露时间各半的地方划分海陆界线呢?究其原因,是因为陆生植物即便遭受短暂的海水浸淹也难以存活.实质上,海岸线是划分喜盐生物与淡水环境生物的界线,这是海岸线最基本的内涵.不同海岸地貌类型海岸线按以下原则划定:(1)具陡崖的海岸线位于陡崖与海滩的交接线,即后滨的后缘,是高潮时大风浪可以到达的地方.(2)具滩脊的海岸线在滩脊顶部向海一侧的大潮平均水位上方,激浪流或上冲流可以达到的最远位置;如果有潟湖发育,则潟湖岸线应量计在内.(3)潮滩海岸线附近的盐蒿、柽柳、芦苇等骤然减少,且植株变小,潮滩海岸线一般划在耐盐植物群落生长状况发生明显变化的地方;同样,发育潮滩滩脊(贝壳堤)的潮滩海岸,堤后潟湖岸线应列入海岸线计量.(4)在河口湾型河口(包括水域),岸线应划在河口区中段的中部.河口中段是过渡区,有一定长度,把水域岸线划在枯水季节咸水入侵界.如果用水的含盐度界定,即枯水季河口区出现水样氯度≤3 150 mg/L的位置,这是一个已使陆生植物完全不能成活的盐度值.(5)凡永久性的人工海岸构筑物,且构筑物所形成的岸线包络足够多的陆域面积,多为城市和种植用地,此构筑物形成的岸线即视为人工岸线.而一般窄而长的防浪、防沙堤或观光堤坝形成的岸线则不计入岸线统计范畴.盐田岸线的划分是个难题.盐田不能生长淡水生物,晒盐要引入海水,且一般趁涨潮自然吸纳或人工辅助吸纳.根据海岸线划法的内涵,应把有涨落潮水自然口门(潟湖口、湾口)纳水的盐田区划归海洋,岸线亦相对沿盐田边缘划出,如盐田区用地下卤水制盐则可例外.一般在海滩、潮滩上建的养殖池等仍以海洋对待.     

Microzooplankton diversity: relationships of tintinnid ciliates with resources,competitors and predators from the Atlantic Coast of Morocco to the Eastern Mediterranean

We examined tintinnid (loricate ciliate microzooplankton) diversity using data from 11 stations between the Moroccan upwelling system and the oligotrophic Eastern Mediterranean. Taxonomic and morphological diversity of tintinnids was compared to phytoplankton distribution and size-structure, to the abundance of competitors in the form of oligotrich ciliates, and predators as copepods. Tintinnid taxonomic diversity was estimated as numbers of species and the Shannon Index, H′; morphological diversity was quantified by substituting size classes of lorica dimensions for species. Total chlorophyll was partitioned into micro-, nano- and pico-fractions using pigment data and a size-diversity was estimated by considering the 3 size classes as 3 species. Along a west-to-east gradient, average water column concentrations of most organism groups declined approximately an order of magnitude yielding tight correlations. However, tintinnid diversity, both taxonomic and morphological, increased from the Atlantic upwelling station into the western basin of the Mediterranean, and declined slightly towards the Eastern Mediterranean, paralleling shifts in the chlorophyll size-diversity estimate. Diversity varied with absolute or relative abundance of oligotrich or copepods, but different diversity metrics were significantly correlated only with phytoplankton size-diversity. We conclude that tintinnid diversity more closely reflects resource diversity than competitive interactions or predation.     

Beach erosion along the coastline of Alexandria, Egypt

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考虑人类活动的海岸线分类体系 ——近期浙江省海岸线调查的实践与思考

海岸线是海陆分界线,定义为多年平均大潮高潮位的痕迹线,兼具海洋与陆地的空间资源管理界限功能。海岸线具有重要的生态功能和资源价值,其功能和价值源于所依附的海岸带。随着海岸带地区的经济与社会快速发展,海岸带资源的保护与开发的矛盾日益凸显。在此背景下,中国构建了以自然岸线保有率为核心的海岸线管理办法。2018年实施的浙江省地方标准《海岸线调查统计技术规范(DB33/T2106—2018)》提出了海岸线的三级分类体系,包括自然岸线、人工岸线和河口岸线3个一级类。该《规范》综合反映了海岸线的科学定义和国家需求。首先,该《规范》给出海岸线定义是"平均大潮高潮时水陆分界的痕迹线",突出了"大潮高潮位"和"痕迹线"对海岸线界定工作的指示意义。其次,该《规范》将自然岸线定义为"由海陆相互作用形成的海岸线",由此推论,人工岸线的地貌动力学功能是隔断了原有的海陆相互作用。第三,该《规范》提出了"原生自然岸线"、"自然恢复的岸线"和"整治修复的岸线"等概念,将曾经受过人类活动影响但恢复了(或拥有了)某种自然海岸形态特征和生态功能的岸线纳入自然岸线的统计口径。由于河口岸线是没有"水陆分界痕迹"可循的特殊类型,现有的海岸线定义未能体现河口岸线的内涵,因此我们建议将海岸线的定义扩展为"平均大潮高潮位的海陆分界痕迹线,以及河流入海口附近按一定规则人为划分的海域与陆域水体的分界线"。从海岸带地貌动力学的角度来看,海岸线的类型和变化主要受地质基底、海平面位置、沉积物供应条件和海岸动力环境等因素影响。因此,海岸线的定义和分类应该综合考虑这四个因素,而人类活动主要从海岸动力作用环境和沉积物供应条件两方面影响海岸带系统状态。     

我国海岸线确定和管理模式研究

文章归纳总结了我国海岸线确定和公布的模式,提出了海岸线确定后的海岸线修订、海岸线区划、海岸线使用和海岸线信息化管理等方面的问题,并对其进行了具体的研究和探讨,为我国海岸线的管理提供了有益的参考。     

Wave diffraction of breakwaters in the presence of a coastline

An integral method is described which is capable of computing the diffraction field produced by waves incident on a breakwater connected to or placed near a straight coastline. Some simple configurations are studied: a straight breakwater protruding normally from the coast, a straight breakwater parallel to the coast, an ‘elbow-shaped’ breakwater with one end connected to the coast, a pair of straight breakwaters protruding normally from the coast and a series of three equal straight breakwaters parallel to the coast. In all cases the water depth is assumed to be constant, while both the breakwater and the coastline walls are supposed to be perfectly reflective. Within the limits of these hypotheses the method is rather general, because breakwaters of arbitrary shape can be considered.     

Wave driven alongshore sediment transport and stability of the Dutch coastline

The wave-driven alongshore sediment transport is commonly supposed to smooth out the irregularities on the coastline. However, it has been shown that waves approaching the coast with a high angle with respect the shore-normal can reverse that tendency and cause the rectilinear coast to be unstable [Ashton, A., Murray, A.B., Arnault, O., 2001. Formation of coastline features by large-scale instabilities induced by high-angle waves. Nature 414, 296–300; Falqués, A., Calvete, D., 2005. Large scale dynamics of sandy coastlines. Diffusivity and instability. J. Geophys. Res. 110, doi:10.1029/2004JC002587]. The extended one-line coastline model presented in the latter paper is here applied to investigate the stability of the Dutch coast. The main aim is testing the hypothesis that the shoreline sand waves observed along this coast could be generated by such an instability. It is found that the Dutch coast has potential for instability. This is most prominent on the Holland coast, followed by the Delta coast and is very weak on the Wadden coast. Whether the instability actually occurs or not depends on the cross-shore bathymetric profile of the shoreline waves. Under the sensible assumption that the bathymetric perturbation is just a shift of the equilibrium beach profile, the Dutch coast is stable. In this case, the mean annual coastline diffusivity is evaluated and it is found to be typically about 0.010–0.015 m² s^− 1, that is, roughly smaller by a factor 2 than that predicted by the traditional one-line model. However, the Dutch coast may be unstable with respect to coastline waves with a maximum bathymetric signal at a few hundred meters from the coast. This is shown in one case where the shoals associated with the sand wave are inside the surf zone during moderate storm waves. Thus the sand waves could result from the cross-shore redistribution of the sand associated with an alongshore series of shoals and bed depressions generated by the alongshore transport in the surf zone. While the generation or not of such shoreline waves by this instability strongly depends on their profile, its propagation once they have been created is less sensitive and is well reproduced by the present model. It is explained why the propagation is to the NE along the Delta and Wadden coasts, why it is faster on the latter and why on the Holland coast there is no clear propagation direction.     

Impacts of storms and evolution of the coastline in western France

The morphological impact of storms on coastal accumulations varies considerably in space along the coast of western France. At some locations, the storm produces erosion, whereas at others, impacts may vary from erosion to accumulation, or no effect. This is explained by the variability of incident waves. Wave amplitude variability, cross-checked with wave direction variability, is presented on a phase diagram and shows that the response of the coast is not linked to the absolute values reached during the storm, but to changes in wave patterns that take place during the event. The morphology of the bottom (skerries, banks) is greatly forcing these changes because of the high tidal range and the complicated and fast-changing patterns of refraction. Locations with a flat seafloor have an almost predictable response to storms. Places with a complex submarine morphology have a response characterized by high variability. The variability of the wave pattern during a half tidal cycle storm (from low tide at 1 m to high tide at 13 m in 6 h) is a microscale equivalent of the variability of wave patterns changing during sea level rise in the Holocene (from −7 to 0 m in 6 ka). This fact explains why, during the late Holocene, the same locations (1) have displayed a very chaotic response to sea level rise and (2) are displaying, today, a highly variable response to storms. In that respect, seafloor morphology is a mesoscale to macroscale control on beach/barrier behaviour.     

黄河三角洲近期海岸线演变与预测

选择1976—2020年9期Landsat卫星遥感影像提取海岸线,从海岸线类型多样性指数、海岸线粗糙度、岸线变迁速率对黄河三角洲地区岸线近期演变进行定量分析,并对2030年海岸线形态进行预测,结果表明： 44年来,海岸线类型多样性指数变大,海岸线类型趋向多样化;海岸线形态粗糙,海岸线粗糙度曲线由相对平滑变为相对粗糙,形成众多“锯齿”状波动,后逐渐变平滑;河口地区岸线快速向海推进,河口两侧地区岸线则以退蚀为主;部分人工岸线向海快速推进后基本保持不变;经预测,2030年黄河三角洲河口地区,清8汊流路附近及宋春荣沟至虎头崖段岸线向海延伸,东风港至孤东油田段海岸线以侵蚀后退为主。     

Approaches to the study of cheniers along the coastline of the Soviet Union

With the very extensive coastline in the north and northeast and the relatively shorter coastlines in the south, cheniers in the USSR can occur in a great variety of climatological conditions ranging from subarctic to subtropical. Cheniers in the USSR have been studied since approximately 1900, the investigations being mainly concerned with the palaeogeographical aspects. Since the 1960's, investigations have focussed on contemporary morphodynamics. Chenier formation appears to depend largely on the relative influence that marine and fluvial factors have on the formation of marginal deltaic plains. Research in this field is briefly reviewed.     

中国南方大陆海岸线时空变迁

海岸线变迁对于海岸带生态环境变化乃至全球变化研究具有重要意义。通过对5个时相TM影像的人机交互解译,获取1990年,1995年,2000年,2005年和2010年中国南方大陆海岸线信息,分析了各时段岸线变迁特征及变迁原因。结果表明:(1)中国南方大陆海岸线的长度和分形维度保持相对稳定,但岸线长度存在总体缩短和局部增长的演化趋势。(2)岸线海向推进的岸段占据主要部分,陆向缩退岸线仅发生在少部分岸段。(3)长江口—杭州湾南岸和珠江三角洲两个典型岸段的分析表明中国南方大陆岸线的时空变化速率与强度在不断加强。(4)在1990—2010年期间,引起中国南方大陆海岸线时空变迁的人为因素的作用比自然因素显著,并导致人工岸线比重不断增大,自然岸线比重不断下降。     

黄河三角洲多年海岸线动态变迁特征及演化规律

以黄河三角洲1976—2014年的MSS、TM、ETM+影像为数据源,采用一般高潮线法提取不同时期的海岸线,结合RS遥感与GIS技术,对黄河三角洲的岸线变化进行监测.结果表明,1976年以来黄河三角洲的岸线形态及长度均发生了较大变化,其中北部的刁口河流路区岸线向内陆蚀退明显,以海洋侵蚀作用为主,属于蚀退型海岸;清水沟流路区的岸线整体向海域推进,海岸处于进淤状态,属于强淤进型海岸.黄河三角洲岸线变化频繁而快速,黄河的入海流路、水沙量、降水量等是影响黄河三角洲岸线变化的重要因素;行水期黄河三角洲岸线一般以淤进造陆为主,停止行河岸段,海岸侵蚀后退速率趋于缓慢,逐渐地变得相对稳定,在长时间不行水的海岸段,岸线基本保持稳定,随着黄河三角洲海岸带人类工程经济活动的加剧,该区域的海岸线演变受人类的影响越来越大.     

漠阳江入海口海岸线分维及其机制分析

分维数是反映海岸线复杂程度的客观依据。结合国内外海岸线分形研究进展,本文以漠阳江入海口附近海域为研究区,基于Landsat 8 OLI遥感影像对研究区域提取瞬时水边线,并利用潮汐数据进行校正得到海岸线;利用Fractal Fox2.0计算获得该海岸线的分维数为1.071;通过对研究区的分形机制分析,认为漠阳江附近的断裂构造对海岸起宏观控制作用,从而对海岸线的分维值也起了决定作用。根据断裂体系模型计算得到西侧海岸线的理论分维值为1.089,而对数螺线模型计算得到东侧海岸线的分维值为1.171;实际分维值相对理论值偏小,说明海岸带的沉积与侵蚀影响了分维值。此外,根据本区海岸侵蚀原因的分析,对分维机制进行了探究,初步论证的分维值大小可为海岸的冲淤变化研究提供参考。     

宁波市海岛海岸线分类保护与管理策略探析

文章概述宁波市海岛海岸线的地理位置、岸线类型、开发现状等基本情况,分析了海岛海岸线开发利用存在的问题,在此基础上依据保护等级和功能用途将全市海岛海岸线进行分类并探讨针对性管控要求,提出统一空间性资源规划体系、制定市级海岛海岸线规划、规范海岸线利用项目管理、实现监视监测网络全覆盖和修复海岛海岸带自然风貌的策略建议,以期为海岛的保护和开发利用建设和管理工作提供科学指导和参考。