Stratigraphical evidence of Late Holocene barrier breaching and extreme storms in lagoonal sediments of Ria Formosa, Algarve, Portugal     

C. Andrade  M. C. Freitas  J. Moreno  S. C. Craveiro 《Marine Geology》2004,210(1-4):339-362

Stratigraphical, sedimentological and paleoecological studies undertaken in lagoonal sediments of the Ria Formosa barrier lagoon indicate that a number of present-day aligned beaches outcropping within the marsh and detached from mainland (marsh detached beaches, MDB) represent the remnants of former ephemeral flood deltas, which established following barrier breaching induced by extreme storms from circa 1270 BC onwards. Dating of these beaches suggests that they resulted from multiple events of flooding separated both in time and space. Repeated emplacement of tidal deltas following overwash of the same location of the barrier is represented in the stratigraphical record by buried and partly overlapping marsh beaches. It is suggested that further refinement of the data presented in this paper and the extension of the stratigraphic survey to the entire lagoonal space will substantiate the usefulness of the stratigraphic record as a proxy to hindcast a time series of extreme storminess extending far beyond the instrumental and historical records.  相似文献   

福建省海岛生物体的污染物含量及其评价     

蔡清海  吴善 《热带海洋学报》1997,(1)

通过对福建省海岛的鱼类、贝类、甲壳类和藻类生物体中的Hg，Cu，Pb，Zn，Cd，六六六和DDT的测定，结果表明：福建省海岛周围海域的生物体没有受到Hg，Zn和六六六的污染；只有少量的鱼类受到Cu的污染；少量的鱼类和甲壳类受到Cd的污染；一部分甲壳类和贝类受到DDT的污染；甲壳类、鱼类受到Pb的污染较严重。  相似文献   

Spatial dynamics of a nearshore, micronekton sound-scattering layer     

Benoit-Bird  Kelly J; Au  Whitlow W.L 《ICES Journal of Marine Science》2003,60(4):899-913

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南麂岛水资源环境调查与研究     

熊健  应时理 《海洋学研究》1994,12(2):84-91

本文利用１９９２年８月和１９９３年３月国家海洋局第二海洋研究所对南麂岛及其邻近海域的环境调查结果，采用尼梅罗（Ｎｅｍｅｒｏ）环境质量指数法和单因子指标评价法，参照有关标准，对南麂岛地表水和地下水资源进行了现状评价并做了预测。在对调查结果进行分析及查阅历史资料的基础上，对南麂岛的水资源生态环境保护提出了建议。  相似文献   

Structure of Mesozoic oceanic crust in the vicinity of the Cape Verde Islands from seismic reflection profiles     

M. Y. Ali  A. B. Watts  I. Hil 《Marine Geophysical Researches》2003,24(3-4):329-343

Multichannel seismic reflection profile data have been used to determine the internal structure of Mesozoic oceanic crust in the vicinity of the Cape Verde islands. The data show the oceanic crust to be characterized by both dipping and sub-horizontal reflectors. Several lines of evidence argue against the reflectors being scattering artifacts arising, for example, from rough basement topography. Instead, the reflectors are attributed to tectonic and magmatic processes associated with the accretion of oceanic crust at the Mid-Atlantic Ridge. The upper crust shows variable reflectivity due to both dipping and sub-horizontal events. We interpret the dipping reflectors, which have been identified on both ridge-normal and ridge-parallel profiles, as sub-surface expressions of normal faults that formed at or near the Mid-Atlantic Ridge. There is no evidence that the faults are caused by loading of the oceanic crust by either the Cape Verde islands or their associated topographic swell. Some faults, however, can be traced into the overlying sediments suggesting they may have been re-activated since their formation at the ridge. The origin of the sub-horizontal reflectors is not as clear. We believe them to be boundaries of different igneous lithologies, such as that between basalts and gabbros. The lower crust is highly reflective in some areas, whereas in others only a few dipping and sub-horizontal reflectors are observed. Some of the dipping reflectors can be traced into the upper crust, suggesting they are also normal faults. Others, however, appear to be confined to the lower crust. The sub-horizontal, discontinuous, reflectors about 2.0–2.5 seconds two-way travel time below the top of oceanic basement are attributed to the Moho.  相似文献   

浙江南麂列岛有节珊瑚藻(红藻门Rhodophyta)的分类研究     

陈彦伟  姜晶晶  丁兰平  黄冰心  陈万东  林利 《海洋与湖沼》2020,51(1):163-175

利用冷冻切片技术,通过形态学和解剖学方法,对采自我国东海沿岸浙江南麂列岛的大型海洋红藻珊瑚藻目(Corallinales)的有节类群进行了分类学研究。经鉴定,共发现珊瑚藻目有节类群2属5种,分别为珊瑚藻科Corallinaceae叉节藻亚科Amphiroideae叉节藻属Amphiroa的带形叉节藻A.beauvoisii;珊瑚藻亚科Corallinoideae珊瑚藻属Corallina的鳞形珊瑚藻C.confusa、粗枝珊瑚藻C.crassisima、珊瑚藻C.officinalis和小珊瑚藻C.pilulifera。通过较为清晰的解剖学特征图片,对该5种有节珊瑚藻外部形态和内部特征进行了详细的比较与描述。结合近年来国际上有关上述部分物种的分类地位变化,对我国现存的带形叉节藻A.zanata、粗扁节藻Bossiella cretacea和大边孢藻Marginisporum crassissimum的归并问题展开了详细分析与讨论,以期促进对珊瑚藻目海藻分类学有更加深入的理解。  相似文献   

堆积海岸平衡岸线轮廓的解析     

孙毛明  邱建立  楼章华 《海洋学研究》2004,22(2):13-18

对堆积海岸平衡岸线轮廓的三个表达式进行了分析和对比,其中平衡岸线轮廓表达式在一定程度上包含了潮流作用对岸线塑造的影响,适用于对凹岸和沙质海岸岸线轮廓的分析,同时也适用于对凸岸和淤泥质海岸岸线轮廓的分析,因而较基本平衡岸线形态方程和B.A.保保夫堆积岸弧方程适用范围更广。利用平衡岸线轮廓表达式,对舟山群岛金塘山和册子山附近水道的两段岸线轮廓进行了分析,结果表明:两岸段均为堆积岸弧,且理论弧长与实测弧长、理论半径与实测半径的值接近,说明理论岸线与实际岸线形态吻合得较好,同时,金塘山西部岸段较册子山西部岸段岸线形态更趋稳定,但两岸线均未达到稳定状态,目前仍处于演变过程中。  相似文献   

Spatial variability of Posidonia oceanica (L.) Delile epiphytes around the mainland and the islands of Sicily (Mediterranean Sea)     

Giuseppina Pardi  Luigi Piazzi  David Balata  Ilaria Papi  Francesco Cinelli  & Lisandro Benedetti-Cecchi 《Marine Ecology》2006,27(4):397-403

This paper investigates patterns of variability in epiphytes of Posidonia oceanica leaves at various spatial scales around Sicily, including geographical differences among the Mediterranean basins, differences between the small islands and mainland, and the variability among and within replicated meadows in each of the previous conditions. Data on percentage cover of the most common epiphytic organisms were analysed by univariate techniques. Encrusting red algae, encrusting brown algae, filamentous algae, encrusting bryozoans, erect bryozoans, hydroids and Foraminifera were the most abundant taxa. Significant differences in the abundance of taxa were detected among geographical regions, while no significant differences were found between the islands and mainland. At smaller scales, variability was concentrated mostly among leaves 100s of centimetres apart and among meadows a few kilometres apart. These results suggest that both geographical and local processes are important in structuring the epiphytes of P. oceanica leaves in this area of the Mediterranean.  相似文献   

Object-oriented tracking of the dynamic behavior of urban heat islands     

Rui Zhu  Eric Guilbert  Man Sing Wong 《International journal of geographical information science》2017,31(2):405-424

The urban heat island (UHI) phenomenon occurring within urban areas or city-clusters is increasingly becoming a severe problem in the urbanization process. Previous research mainly focusing on static UHI modeled at fixed time instants is not capable to track the evolutionary process of the UHIs in both time and space domains. This research designs an object-oriented dynamic model to reconstruct the evolutionary process of UHIs. Each UHI is modeled as a spatiotemporal field-object with its own life-cycle. The dynamic behavior of an UHI is defined by a series of filiations (e.g. expansion and contraction). The model was implemented in an object-relational database and applied to air temperature data collected from weather stations in hourly basis over 7 days. The behaviors of UHI were extracted from the data. Results suggest that the model can effectively identify different behaviors and status of UHIs, and reveal the spatiotemporal behavior of each of them.  相似文献   

珠江口海岛及海域地质环境与灾害初探   总被引：4，自引：0，他引：4  

詹文欢  孙宗勋  朱俊江  唐诚  丘学林 《海洋地质与第四纪地质》2001,21(4):31-36

珠江口海岛及其邻近海域是华南沿海地质灾害类型较齐全的地区之一，主要有活动断裂、地震、地裂缝、软土、风沙、滑坡、崩塌、地面沉降和海平面上升等。珠江口海岸主要发育弱活动和微活动断裂，活动断裂和断块构造的运动和调整是产生地震活动的主要因素。海平面上升已成为当今世界关注的环境恶化和未来50a内产生严重威胁的灾害。风沙作用和软土地基主要分布于珠江口海岛海岸带及近岸岛屿。本区的地质灾害以内动力类型为主。  相似文献