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1.
Abstract The granulometry of 21 box core sediments from five selected sites in the Central Indian Basin (CIB) have been studied to understand the sediment size characteristics in the Pioneer area before the benthic disturbance experiment. The sediments are predominantly clayey silt. Statistical parameters were determined to understand the control and variations in the grain size. The mean grain size (Mzφ) ranged from 7.0 to 8.6 for the surface and from 6.6 to 8.6 for the subsurface sediments, indicating deposition of very fine fractions during the Neogene period. The sediments were poorly sorted as revealed from the higher ρ1 values (2.7 to 2.9). Higher and negative values of skewness (SK1) indicated a winnowing action of prevailing currents in the area. Average kurtosis (KG) values for the surface (0.4 to 0.8) and subsurface (0.5 to 1.2) showed that sediments were very platykurtic and leptokurtic. Clay mineralogical studies showed that smectite had a wider range (from 6% to 55%) and decreased southward because of its terrigenous origin. The terrigenous influence of the sediments could be documented as far as 12°S. Smectite and kaolinite increased eastward and chlorite decreased southward. This observation positively correlated with the mean current direction in the area. However, the influence of Antarctic Bottom Water (AABW) in the area could be predicted from the southward increase in chlorite content. 相似文献
2.
Surface sediment samples in the near shore area of the north Shandong Peninsula are collected for grain size and element analyses. The results indicate that the surface sediments in the study area are primarily composed of the silt-sized components similar to the Huanghe River. The total concentration of aluminum varies from 5.57% to7.37%(average(6.33 ± 0.40)%), and its spatial distribution is mainly controlled by the grain size. Correlations between the ratio of aluminum to titanium concentration and aluminum concentration, titanium concentration and the mean grain size indicate that aluminum in the near shore surface sediments is affected majorly by the terrigenous source, and partially by the anthropogenic source. The ratios of aluminum to titanium concentrations are larger than the background value of loess matter at some stations due to the existence of excess aluminum associated with human activities. Thus, the sources of aluminum should be identified firstly when aluminum is used as an index of terrigenous matter even in the near shore area dominated by terrigenous deposits. 相似文献
3.
渤海湾西部表层沉积物粒度及黏土矿物特征分析 总被引：1，自引：1，他引：0
对渤海湾西部海域和西岸入海河流中76个表层沉积物样品进行粒度及黏土矿物分析,研究表明该区有3种沉积物类型,黏土质粉砂分布于整个研究区,约占表层样的90%,是研究区最主要的沉积物类型;研究区黏土矿物以伊利石为主,黏土矿物组合为伊利石-高岭石-绿泥石-蒙皂石;渤海湾西部表层沉积物主要来源于海河等渤海湾西岸入海河流中的陆源碎屑物,滦河对研究区基本没有影响,黄河对研究区的影响变得比较小。对于研究渤海湾西岸的沉积特征及沉积物物源、了解陆地河流对于研究区海洋沉积环境的影响有着一定的科学意义。 相似文献
4.
西南印度洋中脊表层沉积物非碳酸盐组分的粒度特征及其地质意义 总被引：1，自引：0，他引：1
The carbonate-free fraction of 20 surface sediments collected from the ultraslow-spreading Southwest Indian Ridge(SWIR) was studied by grain size analysis and mineralogical analysis with X-ray powder diffraction(XRD),stereo microscopy and scanning electron microscopy(SEM). The characteristics of the carbonate-free fraction of the sediments were obtained, and related influential factors were discussed. The results show that the mean grain size of this fraction is in 1.96Φ–8.19Φ, with poorly sorting and unimodal, bimodal or irregular bimodal distribution patterns. Four grain size end members of the fraction are derived with the End Member Model method. The finest end member EM1 shows a significant contribution of terrigenous materials of the aeolian input and sediment carried by the bottom current. End member EM2 with medium size mainly reflects sediment of a siliceous bioclast origin. EM3 and EM4 are interpreted as representing the coarser volcanic materials related to bedrock weathering or volcanic activities. Multi-provenance is the dominant factor controlling the grain size pattern of the carbonate-free fraction of the sediments in that area. In addition, sediment transport processes such as the bottom current and wind are the minor factors that influence the grain size distribution of the carbonate-free fraction sediments. 相似文献
5.
The shore-zone sediments between Jeddah and Yanbu, west coast of Saudi Arabia, are composed mostly of skeletal carbonate sands. The nearshore sediments containing benthic foraminifera, algal fragments and molluscs are multimodal, the mean grain size varying between 0.76 and 2.35 ø. The beach sediments, except samples dominated by cerithid gastropods in some localities, are relatively finer than the nearshore sediments. Although the beaches to a great extent comprise sand-sized material, fine lime muds and coarse clastic gravels occur in certain areas. The dune sediments comprising mostly algal grains and ooids are very fine with 50 percent of the material in the 0.25–0.18 mm size grade. Except a general northward decrease in mean grain size, regional trends in the textural parameters of the sediments between Jeddah and Yanbu are not quite apparent. Lateral variations in the textural characteristics suggest a landward migration of the sediments in the shore zone under the influence of northerly and northwesterly winds. The carbon and oxygen (δ 13C + 4.80 to 4.84‰ PDB) (δ 13O − 0.04 to + 0.53‰ PDB) isotopic ratios of the lime muds occurring in certain shallow margins in the shore-zone, which are much higher than those of the green algae, indicate that the fine carbonates are at least in part inorganic in origin.
Like the shallow-water carbonates in tropical seas, aragonite and high Mg-calcite are the dominant carbonate minerals in the shore-zone sediments. There is a landward increase in aragonite contents caused by the landward migration of fine material from the nearshore. The dominant clay mineral in the nearshore sediments is kaolinite with subordinate swelling chlorite and little illite. Kaolinite is contributed by the coastal regions under the sub-tropical humid climate. Swelling chlorite is considered to have been formed in the nearshore by mechanical mixture of chlorite and montmorillonite derived from the metamorphic and igneous terrains of the Tertiary mountains bordering the coastal plain. 相似文献
6.
北部湾东北部表层沉积物主微量元素空间分布特征 总被引：1，自引：0，他引：1
A multi-index analysis including grain size, major and trace elements is performed on the surface sediments from the northeastern Beibu Gulf to trace the sources of the sediments and to understand the controlling factors for elements distribution. The mean grain size exhibits a wide variation ranging from 0.09Φ to 8.05Φ with an average value of 5.33Φ. The average contents of major elements descend in an order of c(SiO_2)c(Al_2O_3)c(Fe_2O_3)c(CaO)c(MgO)c(K_2O)c(Na_2O)c(TiO_2)c(P_2O_5)c(MnO), while those of trace elements exhibit a descending order of c(Sr)c(Rb)c(V)c(Zn)c(Cr)c(Pb)c(Ni)c(Cu)c(As). On the basis of elementary distribution characteristics and statistical analyses, the study area is divided into the four zones: Zone I is located in the northeastern coastal area of the gulf, which receives large amount of fluvial materials from local rivers in Guangxi and Guangdong, China, and the Qiongzhou Strait; Zone Ⅱ is located in the center of the study area, where surface sediments exhibits a multiple source; Zone Ⅲ is located in the Qiongzhou Strait, where surface sediments are dominated by materials from the Zhujiang River and Hainan; Zone IV is located in the southwest of the study area, where surface sediments are mainly originated from the Red River and Hainan. The statistical analyses of sediment geochemical characteristics reveal that the grain size, which is mainly influenced by hydrodynamics and mineral composition of terrigenous materials, is the leading factor controlling the elementary distribution.Meanwhile, impacts from anthropogenic activities and marine biogenic process will also be taken into consideration. 相似文献
7.
楚科奇海盆M04柱晚更新世以来沉积古环境记录 总被引：1，自引：0，他引：1
对"中国第五次北极科考"采自楚科奇海盆的M04柱进行粒度、冰筏碎屑、黏土矿物、岩心XRF扫描、沉积物颜色分析,初步建立了楚科奇海盆晚更新世MIS4期以来的沉积地层框架。MIS4期以来,楚科奇海盆M04柱沉积物粒度和黏土矿物组成具有明显的冰期/间冰期变化特征,冰期沉积物粒度分布以双峰态为主,由洋流搬运和海冰搬运沉积组分组成,伊利石含量高、高岭石含量低;间冰期沉积物具有三峰态粒度分布特征,由海冰搬运、洋流搬运和冰山搬运沉积组分组成,伊利石含量低、高岭石含量高。通过M04柱黏土矿物组合类型与北冰洋边缘海盆的表层沉积物黏土矿物组合类型对比表明,晚更新世以来楚科奇海盆沉积环境发生显著变化:温暖的间冰期受波弗特涡流驱动,波弗特海为研究区的物源输入提供了主要贡献;寒冷的冰期表层环流呈反向输运,细颗粒物源碎屑以东西伯利亚海的输入为主。 相似文献
8.
《African Journal of Marine Science》2013,35(3-4):511-524
The textural and compositional characteristics of the surficial shelf sediments north and south of the Orange River Delta are reviewed and compared. Sediments are fractionated and dispersed both north- and southwards of the Orange River mouth by wave action, longshore drift and subsurface currents. The mean grain size decreases both offshore and southwards in response to decreased wave influence at the seabed and the competence of the weak poleward undercurrent respectively. The increasing dominance of marine biogenic components in sediments south of the prodelta indicates a greater marine influence, modifying previous inferences that the Namaqualand mudbelt is primarily derived from the southward transport of Orange River sediments. A sharp distinction can be drawn between sediments of the Orange Shelf to the south and the Walvis Shelf to the north. Foraminiferarich deposits that dominate the Orange middle shelf and slope indicate that upwelling is an inner-shelf phenomenon. On the Walvis Shelf, foraminiferal sediments are confined to the slope and outer shelf. Fish debris is more common in Walvis Shelf sediments. Although phosphorite and glauconite sands often occur together in the same deposits on the Orange Shelf, the two minerals are concentrated in separate deposits on the Walvis Shelf. 相似文献
9.
Tapas Kumar Mallik 《Marine Geology》1976,22(1):1-32
Shelf sediments at the mouth of the Hooghly River which forms the western part of the Ganges—Brahmaputra delta consist of sands, silts and clays and their various admixtures. The bulk of the sediments consists of moderately sorted fine sand to very fine sand. There is variation in lithology in the vertical and horizontal directions, as revealed from the study of the grab and core samples collected in this area, suggesting growth of the delta in different stages. In most of the samples three populations have been recognised. The grain-size variation has resulted from mixing of a number of different grain-size populations. A detailed study of the heavy minerals indicates that the suite consists of hornblende, tremolite/actinolite, opaques, zircon, pyroxenes (ortho-and clino-), garnet, sillimanite, chlorite, muscovite, biotite, epidote, monazite, kyanite, staurolite, riebeckite, carbonates and glauconite. The assemblage and the distribution patterns suggest two distinct mixed igneous and metamorphic sources for the sediments—the Himalayas to the north, mainly drained by the Ganges—Brahmaputra and their tributaries, and the peninsular shield drained by the Dhamra and other easterly-flowing rivers debouching into the Bay of Bengal. The mineralogy of the core samples in the top and bottom layers does not differ, indicating that the source area remained the same during the time of deposition of the sediments. The mineralogy of the sediments in this area, when compared with the mineralogy of the Deep-Sea Drilling Project site in the Bengal fan situated very far to the south, shows similarity because the sediments of the Ganges are carried to the deep-sea. Depending on the mineral assemblage, the area has been divided into four distinct zones: (1) Hooghly River province, consisting of hornblende, tremolite/actinolite, epidote and garnet; (2) a mixed province characterised by epidote, monazite, zircon, kyanite, staurolite, hornblende, tremolite/actinolite, biotite; (3) Dhamra River province characterised by opaques, sillimanite and orthopyroxene; (4) an offshore province comprising muscovite, chlorite and pyroxene. ILlite and kaolinite are the principal clay minerals in the sediments. The mineralogical, grain size and the lithologic studies of the sediments from the core samples suggest a southward to south-southwestward direction of dispersals of the sediments in the eastern part of the area. 相似文献
10.
海陆交互作用下的南黄海沉积环境复杂，其沉积机制一直是古海洋研究的重点和难点。本文以取自南黄海中部泥质区的Z1岩心为载体，对196个样品的粒度和整体有机质指标(TOC、TN、TOC/TN和δ13Corg)进行了详细分析，并对5个层位进行AMS14C年龄测定，分辨率高达11 a/cm。研究结果显示，6.1 ka BP以来南黄海中部沉积过程可分为3个阶段:(1) 6.1～5.2 ka BP，沉积物粒度较粗，以残留砂和陆源粗粒物质为主，有机质含量较低且主要为陆源输入，本阶段多受东亚季风强盛的影响，动荡海洋环境下有机质保存效率低，大量陆源输入冲淡作用显著；(2) 5.2～3.9 ka BP，沉积物粒度变细且波动较大，有机质呈增加趋势且以海源为主，主要受东亚冬季风减弱的影响，海源有机质含量增加，与黄海暖流影响增强有关；(3) 3.9～0 ka BP，沉积物粒度最细且相对稳定，有机质含量继续增加，直至1.9 ka BP趋于稳定，主要受现代环流系统和东亚冬季风影响。结果表明，南黄海粒度和整体有机质指标变化过程复杂，显示中全新世以来南黄海中部泥质区沉积环境演化的复杂性。本研究获得了南黄海高分辨率的沉积环境演化记录，不仅为沉积机制研究提供更多数据支撑，还可为区域古气候和古海洋演化提供关键的指示证据。 相似文献
11.
The feasibility of an artificial neural network based approach is investigated to estimate the values of mean grain size of
seafloor sediments using four dominant echo features, extracted from acoustic backscatter data. The acoustic backscatter data
were collected using a dual-frequency (33 and 210 kHz) single-beam, normal-incidence echo sounder at twenty locations in the
central part of the western continental shelf of India. Statistically significant correlations are observed between the estimated
average values of mean grain size of sediments and the ground-truth data at both the frequencies. The results indicate that
once a multi-layer perceptron model is trained with back-propagation algorithm, the values of mean grain size can reasonably
be estimated in an experimental area. The study also revealed that the consistency among the estimated values of mean grain
size at different acoustic frequencies is considerably improved with the neural network based method as compared to that with
a model-based approach. 相似文献
12.
长江口外缺氧区沉积物中氧化还原敏感性元素的"粒控效应" 总被引：11，自引：0，他引：11
对长江口外缺氧区及其邻近海域表层沉积物和沉积物岩芯样品的粒度和元素（主要包括氧化还原敏感性元素简称RSE,和典型陆源碎屑元素）进行了分析,并对元素的“粒控效应”进行了深入研究.结果表明,在近岸底层水溶解氧浓度正常海区沉积物中,元素（包括典型陆源碎屑元素和RSE）的分布显示出明显的“粒控效应”,在缺氧区沉积物中,RSE与粒度之间的相关性较差,其分布不受“粒控效应”的制约,而主要受氧化还原环境的影响.另外缺氧区缺氧程度的不同会导致不同的RSE的富集. 相似文献
13.
本文以太平洋CC区西区12个表层沉积物样品作为研究对象,对其粒度、化学组分和矿物成分进行分析,讨论其沉积环境和物质来源。研究区地处深海,主要以深海黏土和硅钙质黏土为主,含有少量的硅质黏土、黏土质硅质软泥和黏土质钙质软泥。黏土矿物成分主要是蒙皂石和伊利石,含有部分的高岭石和绿泥石。黏土矿物组成表明,区内沉积物主要是陆源,由高空气流携带而来,南极底流和热液活动对其物源的来源有一定影响。沉积物地球化学特征也表明,物源以陆源为主,稀土元素分布曲线和北太平洋表层海水稀土曲线类似,且表现出强的Ce亏损,表明生物活动导致的生物沉降对表层沉积物也有一定的影响。 相似文献
14.
冲绳海槽中部沉积物物质来源和沉积环境分析 总被引：1，自引：1，他引：0
本文基于AMS14C高精度测年,通过对柱状沉积物HOBAB2-S2的粒度、微量元素和稀土元素的分析,对冲绳海槽中部区5 300 a以来的物质来源和沉积环境进行了研究。通过对该孔的稀土元素与微量元素的研究发现研究区沉积物质具有陆源属性,并且通过不同物源区沉积物的稀土元素散点图表明5 300 a以来沉积物主要来自于台湾。文中将粒度特征作为研究区域沉积环境,尤其是水动力（黑潮）强弱的指示参数,根据粒度变化曲线,可将沉积过程分为4个阶段:第一阶段（5.30~3.81 ka BP）,粒径由粗变细,黑潮强度逐渐减小;第二阶段（3.81~2.70 ka BP）,粒径波动较大,无明显增大或减小趋势,表明沉积环境处于相对波动状态,水动力强弱不稳定;第三阶段（2.70~0.97 ka BP）,粒径变化较小,表明沉积环境处于相对稳定状态,研究区的水动力条件较稳定;第四阶段（从0.97 ka BP至今）,粒径逐渐变粗,水动力条件增强。 相似文献
15.
Sediment trapping and bypassing characteristics of a stable tidal inlet at Kaohsiung Harbor, Taiwan 总被引：2，自引：0，他引：2
Around the artificially stabilized tidal inlet that connects Kaohsiung Harbor to Taiwan Straight, 203 surficial samples of the sea floor were taken from the nearshore, in the outer harbor, and portions of the inner harbor. The bathymetry of the same area was also surveyed. The sand fraction in each sample was analyzed for the grain-size composition with a custom-built rapid sediment analyzer. A total of twenty-one size-classes were used in the analysis. Three hypothetical sediment sources were assumed to have influenced the spatial grain-size patterns in the study area: the northward and southward littoral drifts, and the sediments exported from the harbor. After reducing the influence of each hypothetical sediment source separately, the data were analyzed using empirical orthogonal (eigen) function (EOF) analysis. The results indicate that the northward long-term littoral drift is the dominant direction of sediment transport in the nearshore of the study area. A conceptual model for four different sediment trapping and bypassing patterns are proposed. (1) Excess bypass (or net outflux): this bypass pattern is characterized by the export of fine-grained sediments (mud and size classes in the very fine sand fraction) from the interior of the harbor. (2) Partial bypass (or partial trapping): this bypass pattern is represented by the size-classes in fine sand fraction. The amount of these grain sizes entering the outer harbor through the inlet is more than the amount exiting at the inlet mouth, resulting in the retention of a portion of these grain sizes. (3) Total bypass (or zero trapping): grain sizes that exhibit this bypass pattern do not come near the mouth of the inlet. These grain sizes include medium and coarse sand fractions. (4) Lag deposits: this group includes the size classes in the very coarse sand fraction, which are largely concentrated in the scour pit immediately seaward of the inlet mouth. In general, surficial sediment grain-size patterns represent a time-averaged response of the substrate to the transport processes over the time scale of at least two seasons. The differential associations of grain-size groups with various topographic features in the study area suggest morpho-textural relationships exist between the sea floor topography and grain size distribution patterns. 相似文献
16.
通过对庙岛群岛西部海域表层沉积物常量、稀土元素的系统研究,探讨了表层沉积物元素地球化学特征、控制因素及其物质来源。结果表明,庙岛群岛西部海域表层沉积物常量元素以SiO2和A12O3为主,SiO2含量随着沉积物粒径变粗逐渐增大,Al2O3含量随着沉积物粒径变细逐渐增大。稀土元素(Rare Earth Element,REE)呈现轻稀土元素(Light Rare Earth Element,LREE)富集、重稀土元素(Heavy Rare Earth Element,HREE)平坦以及中等程度的Eu负异常等特征,轻重稀土分异明显,稀土元素球粒陨石配分曲线与黄河沉积物类似。通过因子分析和相关性分析发现研究区沉积物的元素含量主要取决于陆源碎屑,海洋生物沉积和化学作用对沉积物元素含量有一定的影响,元素含量基本服从粒度控制规律。物源判别结果显示,庙岛群岛西部海域沉积物主要来源于黄河物质和辽河物质,并且从南到北辽河物质的混合比例逐渐升高,黄河物质的混合比例逐渐降低。 相似文献
17.
K. Pehlivanoglou 《Geo-Marine Letters》2001,21(2):75-85
The surface sediments of the Kafireas Strait and Petalion Gulf, the area between the islands of Evvoia, Andros, Gyaros and Kea in the Aegean Sea, were examined for grain size, mineralogical composition and geotechnical properties. Contents of sand, silt, clay and carbonates as well as porosity, absolute and relative water contents, grain density and bulk mineralogy were determined in samples collected at 35 localities during two oceanographic cruises in April 1986 and July 1991. In addition, current measurements were carried out at three localities in the periods May-June 1988 and July 1991. Muddy sand and sand (52-96% sand) cover the continental shelf, whereas sandy mud (3-49% sand) predominates in deeper areas. Absolute water content varied between 22 and 42%, whereas the values for relative water content were 28-73%. Porosity showed a moderate range of values (36-62%), whereas grain density varied between 2.52 and 2.77 g/cm3. Carbonate content showed a wide range of values (30-72%). Mica and kaolinite are the dominant minerals (average contents 32 and 16.6%, respectively), and quartz, plagioclase, calcite and aragonite showed lower contents of 12.9, 9.8, 13.5 and 9.6%, respectively. Higher mica, kaolinite, chlorite and plagioclase contents closer to Evvoia Island may be related to local mica-amphibolitic-chloritic schists and cipollin outcrops, whereas higher percentages of mica, calcite and aragonite probably relate to the mica schists and marbles of Andros Island. Strong currents were recorded near the seabed in the vicinity of the Kafireas Strait (24 and 38 cm/s maximum velocity on the continental shelf off Evvoia and Andros islands, respectively). The regional geomorphology and bathymetry, the texture and mineralogical composition of terrigenous material, and the particular meteorological and hydrodynamic conditions in the area are the main factors which control the texture, mineralogy and distribution of seabed sediments in the vicinity of the Kafireas Strait. 相似文献
18.
南海北部陆坡50 ka 以来黏土矿物来源与输运机制分析 总被引：2，自引：2，他引：0
在 AMS14C 定年的基础上,对南海北部 KNG5站和 KNG7站柱状沉积物中的粒度和黏土矿物进行了研究.KNG5孔黏土矿物组合的基本特点是以伊利石、绿泥石和高岭石为主,蒙脱石含量次之.而 KNG7孔黏土矿物组合的基本特点是以伊利石、绿泥石和蒙脱石为主,高岭石含量次之.物源分析进一步表明, KNG5和 KNG7孔高岭石主要来自于珠江,蒙脱石主要由吕宋岛提供,伊利石和绿泥石分别由珠江和台湾提供.相对于 KNG5孔而言, KNG7孔沉积物受珠江影响较小,而受台西南影响较大.由物源分析推测,珠江对南海北部的物源供应存在一个明显的界线,而这一界线可能位于 KNG5孔和KNG7孔之间,越过这一界线随着离岸距离的增加,南海北部陆坡陆源沉积物受珠江影响明显减弱,而主要由台湾贡献. 相似文献
19.
根据７个岩芯粘土矿物的研究，马里亚纳海槽晚更新世以来的沉积物中主要粘土矿物是蒙皂石，其次是少量ＦｅＭｇ绿泥石和伊利石．蒙皂石和ＦｅＭｇ绿泥石主要是海底基性火山物质蚀变形成的自生矿物，伊利石主要是来自海槽北面和西北面陆上岩石的风化产物．蒙皂石由海槽北部向南部呈增加趋势，而伊利石则呈减少趋势．此外，在距今大约４５ｋａ～１０ｋａ形成的地层中蒙皂石呈减少趋势，伊利石则呈增加趋势．上述粘土矿物组成及分布主要与物质来源、火山活动、海底浊流以及古气候变化的影响有关． 相似文献
20.
《Journal of Sea Research》1999,41(1-2):119-128
With the help of about 500 samples of surface sediments from the North Sea crude maps of the distributions of the clay minerals illite, chlorite, smectite and kaolinite were constructed. Illite, with 51%, is the dominant clay mineral, followed by smectite (27%), chlorite (12%), and kaolinite (10%). There are well-distinguished areas of different concentrations of the individual clay mineral associations. Illite and chlorite show highest values in the north, kaolinite concentrations are high in a corridor a few hundred kilometres wide between the east coast of the UK and the Danish/south Norwegian coast. Smectite is high in the German Bight and in the southwestern North Sea. The distribution patterns of the clay mineral associations are mainly explained by late Quaternary history and by recent to sub-recent sedimentary processes. During the Pleistocene cold periods illite- and chlorite-rich sediments from the Fennoscandian Shield were transported by the great inland ice-masses in a southward direction. The present high sea-level erosion on the east coast of Great Britain provides the North Sea with kaolinite-rich fine-grained sediments. Smectites inherited from Elsterian deposits in the southeast corner and probably from sub-recent Elbe sediments are responsible for their higher values in the German Bight. The high values of smectite in the southwest may have originated from Cretaceous sediments eroded on the banks of the Strait of Dover. The present contribution of riverine suspended load to the North Sea appears to be low. 相似文献