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1.
After the breeding season, Slavonian grebes (Podiceps auritus) leave their freshwater breeding habitats and migrate to wintering grounds in marine or brackish waters. The most important wintering area in northwestern Europe is located in the southern Baltic Sea, with the largest concentrations in the offshore area of the Pommeranian Bight. Analysis of ship-based surveys revealed that the habitat selection of Slavonian grebes in this brackish area is significantly influenced by water depth and bottom sediment type. The grebes prefer shallow waters of 4–14 m depth and occur only over sandy sediments. While the diving depths of endothermic animals is limited due to energetic constraints and thermoregulation, sediment type is regarded to be a proxy for food choice. The diet of Slavonian grebes in the Pomeranian Bight consists mainly of demersal gobies (Gobiidae) that frequently occur over sandy bottom substrates. 相似文献
2.
秋季长江口水体颗粒有机碳年际变化及影响因素分析 总被引：1，自引：0，他引：1
根据2007—2012年长江口及其邻近海域4个航次(11月)调查资料,探讨了长江口秋季颗粒有机碳(POC)时空分布特征;结合长江口环境要素和陆源输入(径流、输沙),分析了秋季POC分布的主要影响因素。结果表明:(1)2007—2012年秋季长江口POC浓度范围为0.03—16.95mg/L,均值2.30mg/L,底层POC浓度高于表层。长江口表层POC浓度存在显著的年际变化特征。(2)长江口区POC分布呈现沿长江径流入海方向降低的趋势,高值区出现在口门附近偏南部水域。口门内和近岸水域POC显著高于近海水域。口门水域POC年际间相对稳定,近岸和近海水域年际变化显著。(3)长江口POC分布与盐度呈非保守性变化,悬浮物是POC分布的主要控制因素,多数年份POC与叶绿素a相关程度较弱。(4)河口来水来沙量对POC浓度具有较强的制约性,径流的主要影响区域在口门内和近岸区,输沙的主要影响区域在最大浑浊带和长江口北部水域。(5)入海输沙量与长江口水域POC相关性最强。咸淡水交汇引起的悬浮物沉积和沉积物的再悬浮强度决定口门内水域POC浓度,浑浊度较高的近岸水体POC对陆源输入泥沙的依赖性较强,长江口外侧海域初级生产力水平成为POC浓度的重要影响因素。 相似文献
3.
Offshore exploration during the 1960's for gold off southern New South Wales and for tin in Tasmanian waters did not result in the discovery of economic deposits. Although very rich gold-bearing beach placers were worked in the past, individual deposits were small and rested on bed rock; the chances of locating and exploiting similar deposits offshore appear to be remote. In the case of tin, sub-economic resources were outlined in submerged river channels at a number of places off northeastern Tasmania. Such channels can be outlined by seismic methods, but to locate workable tin deposits in the buried alluvium by drilling alone is likely to be impracticable and successful exploration may depend on the development of other geophysical prospecting techniques.
Large resources of rutile- and zircon-bearing heavy-mineral sands have been indicated off the east Australian coast by mining company work, but no economic deposits have been found to date. Studies of the morphology of the eastern shelf by the Bureau of Mineral Resources have revealed linear features believed to be related to shore lines developed during Quaternary low sea-level still stands. The most persistent of these off northern N.S.W. are about 105 m, 85 m, and between 35 and 45 m below present sea level. A widespread change of slope at a depth of 20–30 m marks the base of the main body of the present-day paralic-zone wedge of sediment, but seismic profiles indicate that a veneer of recent sediment commonly extends seawards into water depths of about 100 m. Much of the outer shelf is floored by relict sediments and extensive areas of bed rock crop out on the middle shelf.
Virtually all sub-surface data from company drilling for heavy-mineral sands relates to the present-day paralic-zone wedge of sediments; this wedge includes undisturbed sedimentary sequences deposited during pre-Holocene high sea-level periods. No large economic-grade deposits have been outlined by this work offshore, and there is reason to believe that the bulk of the heavy-mineral deposits formed during Holocene and previous high sea-level stands are located above present sea level. In addition, the best-developed submerged strand lines are in deep water probably inaccessible to mining. Nevertheless, the possibility that substantial deposits occur offshore in moderate water depths exists.
Outcrops of bed rock are extensive in the mid-shelf zone in the southern part of the area, but north of 29° S they are much less common. Significant areas with sediment thicknesses greater than 20 m in water depths of less than 60 m occur to the east of Newcastle, to the southeast of Smoky Cape, and to the north of Yamba. Two sediment sequences, an upper and a lower, are recognizable. Highest heavy-mineral values in surface sediments occur offshore from the Permo-Triassic basins. Subsurface enrichment may occur at the junction of the upper and lower sequences, or where the upper sequence overlies basement. The abundance of heavy minerals is a function of the total sediment throughput, and the intensity and direction of shore-line sorting, so that the highest potential for accumulation occurs in the northern part of the area.
The most likely prospective areas occur mainly near Cape Byron and near Sugarloaf Point. These areas have been defined on the basis of the thickness of sediments, the depth to the base of the upper sequence, the distribution of ancient strand lines, and the abundance of heavy minerals in the surface sediments. 相似文献
4.
受径流输沙、风浪、潮汐等影响,河口近岸海域悬浮泥沙具有显著的时空变化。本文基于小时分辨率的GOCI遥感影像,利用最优遥感反演算法,结合空间分析和统计方法,深入研究黄河口及邻近海域悬沙时空动态特征及驱动机制。结果表明,径流输沙对悬沙浓度的影响以河口近岸区为主,高径流输沙对悬沙浓度分布影响可达距岸约20 km,并向孤东近岸方向扩散。大风可引起清水沟老河口区泥沙强烈再悬浮,形成高浓度悬沙区。涨落潮对小时尺度的悬沙浓度影响显著,并影响悬沙的南北扩散。大潮悬沙浓度变化和扩散范围均大于小潮,潮流流速不同是造成该差异的主要原因。水深与悬沙浓度之间存在较明显的负相关关系,根据不同驱动因素的差异,悬沙浓度随着水深的增加呈现出指数型、幂函数型、线性3种关系。 相似文献
5.
2007年和2010年在厦门湾及邻近海域进行底质表层沉积物和柱状岩心样品采集,并进行粒度分析及粒度参数计算,获得了研究区底质表层和柱状沉积物样品的粒度分布特征.结果表明,厦门湾海域沉积物类型多样,以粉砂质砂和砂质粉砂为主.平均粒径介于?1.5Φ~7.5Φ之间.采用 Gao-Collins粒径趋势分析方法,发现九龙江口的沉积物主要呈东南方向净输运,而大金门南侧海域沉积物则有向九龙江口输运的趋势,同安湾内沉积物由海岸向湾中央输运;厦门东部海域沉积物向北输运,翔安南部海域沉积物向同安湾口以及澳头近岸输移.对柱状岩心进行放射性同位素210Pb 测年分析,计算得到九龙江口沉积速率为2.62 cm/a,进而探讨了九龙江口的沉积环境演化特征,研究成果可为区域资源开发和环境保护提供科学依据 相似文献
6.
渤海湾内海岸的连续开发导致岸线 、海床发生较大变化, 同时影响着湾内的水沙通量。根据不同时期的遥感影像、 实测地形和水文泥沙资料, 统计分析了渤海湾岸线 、面积和海床冲淤变化, 构建了渤海潮流泥沙数学模型, 模拟了 1984 年、 2006 年和 2015 年三个时期的水沙分布, 探究了海岸连续开发对水沙分布和通量引起的累积效应。结果表明： 渤海湾岸线和 海湾面积变化主要发生于 2005 年后, 与 1984 年相比, 2020 年的岸线长度增长超过 185%,海湾面积减少近 19%;曹妃甸港 区南侧海域冲刷基本在 2 m 等深线以内, 而近岸和港池水域基本呈现淤积状态, 淤积幅度在 2 m 以内; 海湾的连续开发利用 使得湾内分潮波振幅增大 、传播速度减缓, 近岸海域的余流变化较为明显,南部较北部海域更甚;西北湾顶 0.2 kg/m3 悬沙 分布区域不断缩小, 西南近岸 0. 15 kg/m3 悬沙分布区域向中部海域推进; 悬沙通量变化与潮流通量并不完全一致, 呈外海增 加、近岸整体降低的变化特征, 湾内向外海输移泥沙的能力减弱。 相似文献
7.
利用单波束测深仪和蚌式取样器进行了日照石臼港扩建码头西侧约50km~2海域1:2 000~1:10 000的水深地形测绘和底质分析工作。调查结果表明,日照港西部海域可分4个水深区,其地形和沉积特征如下:1)航道区,浅水航道区等深线平行于码头岸线,水深11m,经过疏浚已形成向南倾斜的四级阶梯地形,疏浚中心处水深24m。航道区底质以分选中等的砾砂为主;2)港池区,水深6 m,等深线与港池岸线平行,水深向南渐增,海底地形平坦,坡降比3‰。底质以分选较好的粉砂和砂质粉砂为主,近岸有少量分选较差的泥质砂质砾;3)涛雒-付疃河口区,水下三角洲地形明显,5m以浅等深线呈弧形向东南方向凸出,坡降比最大可达14.2‰,底质类型为分选极好的砂和粉砂质砂;4)浅海区,海底地形平坦,平均坡降比1.9‰,6~10m等深线呈NE-SW向平行向外海增大,近南扩码头端向东偏转,底质类型为分选好的砂质粉砂和粉砂,并呈平行于海岸线向深水区呈粗-细-粗的带状分布。底质类型分布与水深条件基本吻合,但深水区出现的底质粗化现象,分析认为可能与南扩码头的挑流作用有关,海底沉积物呈向南运移趋势。 相似文献
8.
Satoshi Yamamoto 《Journal of Oceanography》1979,35(2):91-99
Anisotropic detrital mineral grains were segregated microscopically from the suspended matter in surface waters of the Yellow Sea and East China Sea. Microscopic grain-size measurements of the anisotropic minerals were carried out for more than 80 slide specimens which are distributed homogeneously in the Yellow Sea and East China Sea. The distribution maps of mean grain size and sorting coefficients indicate that the mean size becomes coarser as one goes offshore, and the sorting coefficients are larger in the southern portion and smaller in the northern portion of this region. The clay-sized minerals in the suspended sediments carried out by the deltaic rivers of the continent were deposited in the nearshore area while coarser silt-sized minerals were suspended in offshore waters. The larger sorting coefficients (standard deviations) in the southern portion may imply that the silt-sized grains of offshore waters contain coarser sand-sized grains. The sand-sized grains may be supplied from offshore Taiwan and the Bashi Channel and transported by the main flow of the Kuroshio current. 相似文献
9.
基于2020年7月特大洪水期间长江口浑浊带南槽、北槽和北港多站位同步实测水沙动力数据,研究了河口浑浊带分粒级输沙时空特征及其对泥沙来源响应的指示意义,结果表明：1）北港和北槽是流域泥沙净向口外输移的主要输沙通道,南槽是海域泥沙净向口内输移的主要输沙通道,主槽内粉砂是主要输沙组分,占比63.2%,口外粉砂和黏土是主要输沙组分,分别占43.2%、40.9%;2）大潮粉砂输运占比高于小潮,黏土输运占比低于小潮,口外测站砂组分在大小潮期间在横沙浅滩和九段沙间沿岸输移,横沙浅滩附近大、小潮离岸输沙分别是北港口外的1.7倍和8倍,不利于横沙浅滩淤涨;3）当前流域减沙高达70%,此次特大洪水期间黏土、粉砂和砂三组分近底净向口内输移为减沙背景下的口外供沙提供了有力的佐证。 相似文献
10.
Investigation of the effects of offshore breakwater parameters on sediment accumulation 总被引：1，自引：0，他引：1
Ali Remzi Birben &#x;smail Hakk&#x;
zler Servet Karasu Murat &#x;hsan Kmürcü 《Ocean Engineering》2007,34(2):284-302
Littoral sediment transport is the main reason for coastal erosion and accretion. Therefore, various types of structures are used in shore protection and littoral sediment trapping studies. Offshore breakwaters are one of these structures. Construction of offshore breakwaters is one of the main countermeasures against beach erosion. In this paper, offshore protection process is studied on the effect of offshore breakwater parameters (length, distance and gap), wave parameters (height, period and angle) and on sediment accumulation ratio, one researched in a physical model. In addition to the experimental studies, numerical model in which the formulae of the sediment discharge (i.e. the formulae of CERC and Kamphuis), was used was developed and employed. The results of the experimental and numerical studies were compared with each other. 相似文献
11.
溶解氧(DO)是海洋生物生存不可缺少的要素。随着人类活动的增加,全球近岸海域低氧情况愈发严重,已经成为威胁海洋生态系统健康的重要因素。通过对2017年5?9月秦皇岛外海区域的观测调查,探讨了该海域低氧与酸化的形成机制并计算了月平均耗氧速率。结果表明,5月秦皇岛外海水体混合较为均匀,表、底层DO浓度一致,均大于8 mg/L;6月开始形成密度跃层,与此同时底层DO浓度和pH开始下降;8月底层呈现明显的低氧和酸化状态,DO浓度下降至2～3 mg/L,pH下降至7.8以下;9月随着层化消失,底层水体DO浓度和pH逐渐升高。相关性分析显示,DO和叶绿素a (Chl a)以及pH具有良好的耦合性,说明秦皇岛外海区域的低氧发生过程主要为局地变化。同时表明DO浓度和pH主要受水体中浮游植物的光合作用和有机物有氧分解的影响。通过箱式模型计算得到2017年6?8月密度跃层以下水体及沉积物耗氧速率为951～1193 mg/(m2·d)[平均为975 mg/(m2·d)]。综合来看,水体分层是秦皇岛外海低氧和酸化发生的先决条件,跃层以下的有机物分解耗氧则是底层水体发生低氧和酸化的重要原因。 相似文献
12.
Modelling the tides and their impacts on the vertical stratification over the Sofala Bank,Mozambique
The Sofala Bank, a wide shelf located along the central coast of Mozambique, hosts tides with high amplitudes. The Regional Ocean Modelling System (ROMS) was used to analyse the tidal currents on the bank and to investigate their effects on the stratification and generation of tidal fronts. During spring tides, barotropic tidal currents with maximum values ranging from 40 cm s–1 to 70 cm s–1 are found on the central bank. The major axis of the tidal ellipses for M2 and S2 follow a cross-shelf direction with mainly anticlockwise rotation. Similar to observations, three distinct regimes occur: (i) a warm well-mixed region on the inner shelf where the depths are <30 m; (ii) a wellmixed colder region above the shelf edge; and (iii) a stratified region offshore. The model shows that the tides lead to cooling where two criteria are satisfied: the Simpson and Hunter parameter log10(h/U3) <3.2 and the depth h >30 m. The shelf edge of the bank is important for internal tide generation. Two frontal structures result, one offshore between cooler mixed waters and warmer stratified waters and the other in shallow inshore waters, between cooler mixed waters and solar heated mixed waters. 相似文献
13.
闽北近海柱状沉积物粒度特征及沉积速率研究 总被引：1，自引：0，他引：1
通过对闽北近海柱状沉积物的粒度频率曲线、粒度参数、粒度组成和沉积速率变化等特征分析,探讨闽北近海现代沉积环境条件变化.结果显示,闽北近海沉积物类型单一,以粘土质粉砂为主,粒级变化不大,粒度组成相对集中,粉砂级占绝对优势.频率曲线主要以主次双峰型为主,Zk1、Zk2柱样局部层位为主次三峰形态.Zk1、Zk2、Zk3柱样分别在78、69、87 cm处有不太明显的分段特征,上段平均粒径均略大于下段.研究表明潮流作用是该海域主沉积动力,沉积物主要以陆源物质为主,研究海域的水深整体略有变浅.研究区现代平均沉积速率为1.18～1.23 cm/a,里山湾和台山列岛附近海域沉积物平均沉积速率较快,分别为1.23、1.20 cm/a,大于七星列岛附近海域的沉积速率1.18 cm/a.海水动力条件是主要的控制因素,百年以来里山湾和台山列岛附近海域的水动力大小逐渐减弱,沉积物的沉积速率减小,台山列岛附近海域沉积速率减小幅度比较大;七星列岛附近海域水动力条件逐渐增强,沉积速率缓慢增加. 相似文献
14.
15.
江苏近海海域是具有数十年历史的鸟类学研究地区,对于海洋性鸟类繁殖、保护以及江苏省鸟类名录的修订具有重要地位。本研究首次系统调查、整理了近40年间江苏近海海域鸟类多样性,分析了鸟类多样性的群落结构及与风电、养殖的关系特征。通过对连云港、盐城和南通近海海域以及少数离岸岛屿4个季度的野外调查,共计发现鸟类69种2 393只,隶属于11目27科。其中,雀形目和鸻形目是近海海域鸟类的重要组成类群,鹱形目、鲣鸟目和潜鸟目在江苏近海海域稳定存在。本研究将江苏近海海域记录鸟类丰富至182种。2020年调查发现的鸟类物种占总记录鸟种数的37.91%,首次记录到的鸟种有27种。Pearson相关性检验显示风电建设与鸟类多样性在距离尺度上呈现显著的正相关关系,筏式养殖与鸟类多样性在距离尺度上呈现显著的负相关关系。表明江苏近海海域鸟类对风电场具有明显的规避倾向,而对筏式养殖区域具有明显的依赖倾向。针对当前江苏近海海域生物多样性保护水平较低、人为干扰严峻的背景下,本文研提了基于生物多样性保护的政策建议,为近海海域空间优化和保护地体系制定提供参考。 相似文献
16.
研究近海海域水流、悬沙运动规律，运用基于COHERENS发展的水动力悬沙模型COHERENS-SED,结合当地一般波浪条件，模拟了青岛近海悬浮泥沙输运情况，并验证及分析了水动力环境及悬沙输运的模拟结果。结果表明：在波流合作用下，近岸掀沙明显，大潮期间该海域近岸悬沙浓度值最高可达50mg／L。 相似文献
17.
Although large loads of potentially toxic constituents are discharged from coastal urban watersheds, very little is known about the fates and eventual impacts of these stormwater inputs once they enter the ocean. The goal of this study was to examine the effects of stormwater discharges on the benthic marine environment of Santa Monica Bay. Sediment samples were collected across a gradient of stormwater impact following significantly sized storm events offshore Ballona Creek (a predominantly developed watershed) and Malibu Creek (a predominantly undeveloped watershed). Sediments offshore Malibu Creek had a greater proportion of fine-grained sediments, organic carbon, and naturally occurring metals (i.e., aluminum and iron), whereas sediments offshore Ballona Creek had higher concentrations of anthropogenic metals (i.e., lead) and organic pollutants (i.e., total DDT, total PCB, total PAH). The accumulation of anthropogenic sediment contaminants offshore Ballona Creek was evident up to 2 km downcoast and 4 km upcoast from the creek mouth and sediment concentrations covaried with distance from the discharge. Although changes in sediment texture, organic content, and an increase in sediment contamination were observed, there was little or no alteration to the benthic communities offshore either Ballona or Malibu Creek. Both sites were characterized as having an abundance, species richness, biodiversity and benthic response index similar to shallow water areas distant from creek mouths throughout the Southern California Bight. There was not a preponderance of pollution tolerant, nor a lack or pollution sensitive, species offshore either creek mouth. 相似文献
18.
Suspended matter regime in the Yellow Sea 总被引：3，自引：0，他引：3
John D. Milliman Li Fan Zhao Yiyang Zheng Tiemin Richard Limeburner 《Progress in Oceanography》1986,17(3-4)
Winter and summer oceanographic conditions in the Yellow Sea produce distinctly different distributions and compositions of suspended particles within the water column. During the winter, strong northwest winds cool and mix the local water column and generate surface waves which resuspend bottom sediment in the north Yellow Sea and in the shoal regions of the western Yellow Sea near Jiangsu Province, and transport it southwards. Wintertime suspended particle concentrations in nearbottom waters can exceed 500 mg/l in nearshore areas and 20 mg/l in offshore waters.During the summer, light southerly winds and a strongly stratified water column localize the distribution of resuspended sediments. Nearbottom concentrations of suspended particulates are generally less than 10 mg/l. Nearsurface concentrations generally are not dissimilar from those seen during the winter, but the particles are primarily biogenic rather than resuspended mineral grains. 相似文献
19.
为研究多环芳烃从河口到近海的环境归趋行为与生态风险,考察了沉积物质量浓度、溶解性有机质、温度、盐度4种典型环境因子对菲在黄河口沉积物上吸附的影响,比较了黄河口与近海两种沉积物对菲的吸附性能。研究结果表明,沉积物质量浓度越低,单位质量颗粒物的菲吸附量越高;共存的溶解性有机质对菲的吸附具有增促作用,且腐殖酸比黄腐酸的作用更显著;温度的升高不利于菲的吸附,而盐度的增加有利于菲的吸附。菲在沉积物上的吸附是分配作用与表面吸附两种行为的耦合,其中黄河口沉积物以表面吸附为主,而近海沉积物以分配作用为主。近海沉积物菲吸附量显著高于黄河口沉积物菲吸附量。基于此,菲从河口到近海的迁移过程中,更易于在沉积物表面发生吸附沉降,从而可能降低水相中的生态危害,但对近海底栖生物具有潜在的健康生态风险。 相似文献
20.
Mud volcanoes and gas vents in the Okhotsk Sea area 总被引：5，自引：0，他引：5
Shakirov Renat Obzhirov Anatoly Suess Erwin Salyuk Anatoly Biebow Nicole 《Geo-Marine Letters》2004,24(3):140-149
Gas emissions from mud volcanoes on Sakhalin Island and water-column gas flares arising from cold seeps in the Okhotsk Sea appear to be related. They are likely activated by tectonic movements along the transform plate boundary separating the Okhotsk Sea Plate from the Eurasian and Amur plates. Gas vents (flares) and methane anomalies occur in the waters offshore Sakhalin Island, along with NE-SW-trending mounds and fluid escape structures on the seafloor. The intersection of the NE-striking transverse faults on land with the Central Sakhalin and Hokkaido-Sakhalin shear zones apparently determines the sites of mud volcanoes, a pattern that continues offshore where the intersection with the East Sakhalin and West Derugin shear zones determines the sites of the submarine gas vents. 相似文献