长江口和东海海域沉积物粒径对有机质分布的影响

利用2007年11月采集于长江口和东海陆架区域的78个站位的表层沉积物样品,以及2007年11月、2008年4月采集于长江口东南和浙江近岸泥质区的悬浮物样品,对长江口和东海海域表层沉积物以及部分站位的悬浮物进行了粒度、有机碳和总氮的分析和研究,探讨了沉积物粒径对有机质运移和沉积过程的影响.结果表明:(1)水体中悬浮物的...     

近年来人类活动影响下长江河口的变化模式

To evaluate the controlling factors for coastline change of the Changjiang(Yangtze River) Estuary since 1974,we extracted the mean high tide line from multi-temporal remote sensing images that span from 1974 to 2014 at 2-year intervals.We chose 42 scenes to constrain the changing pattern of the Changjiang Estuary coastline,and implemented GIS technology to analyze the area change of the Changjiang(Yangtze) Subaerial Delta.Runoff,sediment discharge and coastal engineering were withal considered in the analysis of the coastline changes.The coastline has transgressed seaward since 1974,and a part of it presents inter-annual variations.The area of the Changjiang Subaerial Delta increased by 871 km2,with a net accretion rate of 21.8 km2/a.Based on the change of sediment discharge due to the major projects in the Changjiang River Basin,we divided the changing pattern of the coastline into three stages:the slow accretion stage(1974–1986),the moderate accretion stage(1987–2002),and the rapid accretion stage(2003–2014).Liner regression analysis illustrated that there is a significantly positive correlation between the area changes and sediment discharge in the Chongming Eastern Shoal and Jiuduansha.This suggested that sediment load has a fundamental effect on the evolution of the Changjiang Estuary.Construction of Deep Waterway in the North Passage of the Changjiang River(1998–2010) led to a rapid accretion in the Hengsha Eastern Shoal and Jiuduansha by influencing the hydrodynamics in North Passage.Coastal engineering such as reclamation and harbor construction can also change the morphology of the Changjiang Estuary.We defined a contribution rate of area change to assess the impact of reclamation on the evolution of Changjiang Estuary.It turned out that more than 45.3% of area increment of the Changjiang Estuary was attributed to reclamation.     

长江口邻近海域透明胞外聚合颗粒物浓度和沉降速率研究

透明胞外聚合颗粒物（Transparent exopolymer particles,TEPs）在海洋中分布广泛,其沉降被认为是海洋中生物碳沉降的途径之一。本研究于2011年春季和夏季调查了长江口邻近海域TEPs的浓度和沉降速率,并且估算了其碳沉降通量。研究发现,TEPs浓度春季介于40.00~1040.00 μg Xeq L^-1,平均值为209.70±240.93 μg Xeq L^-1;夏季介于56.67~1423.33 μg Xeq L^-1,平均值为433.33±393.02 μg Xeq L^-1。两个季节,TEPs在水华站位的浓度明显高于非水华站位。相关性分析表明,TEPs与水体叶绿素a浓度呈显著正相关性,表明在调查区浮游植物是TEPs的主要生产者。TEPs沉降速率在春季介于0.08~0.57 m d^-1,平均值为0.28±0.14 m d^-1;夏季介于0.10~1.08 m d^-1,平均值为0.34±0.31 m d^-1。经估算,TEPs碳沉降通量春季介于4.95~29.40 mg C m^-2 d^-1,平均值为14.66±8.83 mg C m^-2 d^-1;夏季介于6.80~30.45 mg C m^-2 d^-1,平均值为15.71±8.73 mg C m^-2 d^-1。TEPs的碳沉降通量可以占到浮游植物碳沉降通量的17.81%~138.27%。水华站位TEPs的碳沉降通量明显高于非水华站位,这是由于水华站位较高的TEPs浓度及沉降速率所致。本研究表明,TEPs的沉降在长江口邻近海域是碳沉降的有效途径,在相应的碳沉降相关研究中应该被考虑进来。     

Grain size composition and transport of sedimentary organic carbon in the Changjiang River (Yangtze River) Estuary and Hangzhou Bay and their adjacent waters

Surface sediments from the Changjiang River(Yangtze River) Estuary,Hangzhou Bay,and their adjacent waters were analyzed for their grain size distribution,organic carbon(OC) concentration,and stable carbon isotope composition(δ13C).Based on this analysis,about 36 surface sediment samples were selected from various environments and separated into sand(0.250 mm,0.125–0.250 mm,0.063–0.125 mm) and silt(0.025–0.063 mm)fractions by wet-sieving fractionation methods,and further into silt-(0.004–0.025 mm) and clay-sized(0.004mm) fractions by centrifugal fractionation.Sediments of six grain size categories were analyzed for their OC andδ13C contents to explore the grain size composition and transport paths of sedimentary OC in the study area.From fine to coarse fractions,the OC content was 1.18%,0.51%,0.46%,0.42%,0.99%,and 0.48%,respectively,while theδ13C was –21.64‰,–22.03‰,–22.52‰,–22.46‰,–22.36‰,and –22.28‰,respectively.In each size category,the OC contribution was 42.96%,26.06%,9.82%,5.75%,7.09%,and 8.33%,respectively.The OC content in clay and fine silt fractions(0.025 mm) was about 69.02%.High OC concentrations were mainly found in offshore modern sediments in the northeast of the Changjiang River Estuary,in modern sediments in the lower estuary of the Changjiang River and Hangzhou Bay,and in Cyclonic Eddy modern sediments to the southwest of the Cheju Island.Integrating the distribution of terrestrial OC content of each grain size category with the δ13C of the bulk sediment indicated that the terrestrial organic material in the Changjiang River Estuary was transported seaward and dispersed to the Cyclonic Eddy modern sediments to the southwest of the Cheju Island via two pathways:one was a result of the Changjiang River Diluted Water(CDW) northeastward extending branch driven by the North Jiangsu Coastal Current and the Yellow Sea Coastal Current,while the other one was the result of the CDW southward extending branch driven by the Taiwan Warm Current.     

中小河流对长江水下三角洲远端泥沉积的贡献:以椒江和瓯江为例

海洋沉积物的来源、输运过程及其归宿一直是海洋沉积学的重要研究课题。浙闽沿岸泥区的沉积物主要来自长江及浙闽沿岸的中小河流,对后者的贡献量进行定量化分析是相关研究比较薄弱的环节,这个问题的难点可能是缺乏同时指示"物源"和"供应量"两个指标的示踪物。本文以椒江和瓯江这两条河流对浙闽沿岸泥区的贡献为切入点,运用了粒度端元和黏土矿物两种示踪指标进行研究,目的有两个:一是综合评价两种示踪指标的效率,二是定量化地了解中小河流对浙闽沿岸泥区的贡献。借助端元粒度分析模型对浙闽沿岸泥区的表层样粒度数据进行分解,划分出4个不同的端元,结果显示,EM1端元表现出长江来源的属性,EM2端元表现出椒江和瓯江等沿岸中小河流来源的属性,EM3端元可能来源于研究区南部并有向北输送的趋势,EM4端元可能来源于陆架中部的残留砂沉积区。基于特征粒级的进一步分析表明,研究区6个站位的柱样沉积物中都出现了第一特征粒级,在3.91~9.29 μm之间,推测与长江口外悬浮颗粒物有关,并认为柱样所在的区域都会受到长江入海泥沙的影响。黏土矿物由于具有粒度依赖性,在定量探讨椒江与瓯江的泥沙贡献量时,只能指示小于2 μm的细颗粒物的贡献量,而粒度端元作为一种"全粒度"的指标,在相对封闭的系统内,可以同时解答"从哪里来"和"有多少"这两个示踪问题,是受限比较小的示踪物指标,未来在定量研究物源方面可能会有较大的作用。     

长江水下三角洲表层沉积物粘土矿物分布及其影响因素

采用X射线衍射(XRD)分析技术分析了长江水下三角洲地区65个表层沉积物样品的粘土矿物。结果表明,长江水下三角洲粘土矿物主要由伊利石、绿泥石、高岭石和蒙皂石构成;长江水下三角洲亚环境粘土矿物组成则不同,三角洲前缘亚环境中高岭石和绿泥石的平均含量高于前三角洲的含量,而前三角洲亚环境中伊利石和蒙皂石的平均含量高于三角洲前缘的含量。研究区粘土矿物主要来自长江流域,属于长江源,其分布主要受沉积动力环境和粘土本身性质的制约。     

长江与黄河河口沉积物环境磁学特征及其对比研究

对采自长江现行主河道和黄河入海口处的表层沉积样品进行了环境磁学参数的测量和对比研究.结果表明:长江和黄河河口沉积物的磁性载体主要是亚铁磁性物质,亚铁磁性矿物晶粒以假单畴-多畴为主,同时亦有超顺磁晶粒的存在;长江河口沉积物的磁性明显强于黄河河口沉积物,特别是质量磁化率、非磁滞剩磁及饱和等温剩磁,两者相对偏差在40%以上;在粗粒级沉积物(>0.063 mm)中,长江河口沉积物的磁化率与全样磁化率平均值差别较小,在4%左右;黄河河口沉积物差别很大,可达34%.两者的差别反映了长江和黄河沉积物中磁性矿物赋存方式的差异;长江和黄河河口沉积物磁性特征的差异与两者粒度特征对比明显.长江和黄河河口沉积物的这些磁学方面的差别是源岩特征和气候环境差异上的反映,可以作为判别两者物源的有效示踪剂.     

长江、黄河河口沉积物中生物标志化合物组成的初步研究

该文对长江口、黄河口以及废黄河口现代沉积物中生物标志化合物组成进行分析。结果表明 :长江与黄河沉积物中的生物标志化合物组成有较大的差别 ,长江沉积物中具明显奇偶优势的高碳数正构烷烃以及 C2 9甾烷的相对含量较高 ,Pr/Ph值较大 ,受陆生高等植物的影响明显 ;黄河低碳数正构烷烃和 C2 7甾烷的相对含量较高 ,Pr/Ph值较小 ,受陆生高等植物的影响较弱。甾烷、萜烷的成熟度指数显示长江高于黄河、现代黄河高于废黄河。这些差异主要受流域环境背景和流域内人文过程两大不同因素的影响     

The impact of the Changjiang River plume extension on the nanoflagellate community in the East China Sea

Variation in the summer nanoflagellate community on the continental shelf ecosystem of East China Sea (ECS) is closely coupled with environmental variation due to extension of the Changjiang River plume. Spatial patterns of nanoflagellate abundance were studied in June and August 2003, June 2006 and July 2007 over the ECS shelf. The Changjiang River plume was smaller during the August 2003 and July 2007 cruises than during the rest other 2 cruises. Total nanoflagellates densities varied between 1 and 120 × 10² cells ml⁻¹ with the highest abundances occurring within the Changjiang River plume during large plume periods. In the small plume periods, the range of nanoflagellates abundance was 3–33 × 10² cells ml⁻¹ and the highest abundances were observed during these periods either within the Changjiang River plume or the Yellow Sea Coastal Water (YSCW). During large plume periods, nanoflagellate abundance closely related to changes in salinity and during the small period, abundance was most related to water temperature. The pigmented nanoflagellate community (PNF) within Changjiang River plume, especially in the <3 μm size class, appears to increase in response to terrestrial or anthropogenic inorganic nutrient loading in the discharge of fresh water from the Changjiang River. The PNF abundance pronounced increase caused the variation of nanoflagellate community of ECS in summer. We suggest that the discharge of fresh water from Changjiang River has significant ecological impacts on spatial variations in nanoflagellate community in the ECS.     

近50 a来杭州湾冲淤变化规律与机制研究

使用杭州湾1959-2010年的水下地形图, 结合过去数十年来长江入海水沙量和钱塘江河口段冲淤变化状况, 分析了近50 a来杭州湾在长江入海泥沙量锐减和治江围涂等人类活动作用下的冲淤变化规律及其物理机理。结果表明, 乍浦以上区域近50 a来处于较显著的淤积状态, 且有自上向下发展的趋势, 这种淤积主要是由于钱塘江河口治江缩窄工程所引起的;湾内地形发生了局部调整, 部分小型潮流槽脊系统趋于消亡, 地形趋于平坦化, 湾口北部2003年以后有转淤为冲的趋势, 这与长江入海泥沙量锐减和该区域围垦工程等因素有关;1959-2003和2003-2010年两个时段, 湾内泥沙淤积的年平均值分别为0.91×108和1.66×108 m3。对于整个钱塘江河口系统而言, 即自杭州湾湾口至钱塘江河口段的闸口断面, 长江入海泥沙量减少所产生的影响尚不明显, 2003年以后泥沙淤积速率甚至有所上升。杭州湾近50 a的冲淤变化是人为强烈干预下的大流域-河口系统响应与中小流域-河口系统响应的调整结果。     

Seasonal changes in nitrogen and phosphorus transport in the lower Changjiang River before the construction of the Three Gorges Dam

Water and sediment samples were collected at Datong from June 1998 to March 1999 to examine seasonal changes in the transports of nitrogen (N) and phosphorus (P) from the Changjiang River (Yangtze River) to the East China Sea (ECS). Dissolved inorganic nitrogen (DIN; dominated by nitrate) concentration exhibited small seasonality, and DIN flux was largely controlled by water discharge. Dissolved inorganic phosphorus (DIP) concentration was inversely correlated with water discharge, and DIP was evenly delivered throughout a year. The transports of DIN and DIP from the Changjiang River were consistent with seasonal changes in nutrient distributions and P limitation in the Changjiang Estuary and the adjacent ECS. Dissolved organic and particulate N (DON and PN) and P (DOP and PP) varied parallel to water discharge, and were dominantly transported during a summer flood. The fluxes of DOP and particulate bioavailable P (PBAP) were 2.5 and 4 times that of DIP during this period, respectively. PBAP accounted for 12–16% of total particulate P (PP), and was positively correlated with the summation of adsorbed P, Al–P and Fe–P. Ca–P, the major fraction of PP, increased with increasing percent of CaCO₃. The remobilization of riverine DOP and PBAP likely accounted for the summer elevated primary production in DIP-depleted waters in the Changjiang Estuary and the adjacent ECS. The Changjiang River delivered approximately 6% of DIN (1459 × 10⁶ kg), 1% of DIP (12 × 10⁶ kg), and 2% of dissolved organic and particulate N and P to the totals of global rivers. The construction of the Three Gorges Dam might have substantially reduced the particulate nutrient loads, thereby augmenting P limitation in the Changjiang Estuary and ECS.     

东海内陆架泥质沉积体研究进展

陆架海现代泥质沉积研究具有重要的地质学、环境科学和气候学意义,数十年来一直受到海洋科学家的关注,尤其是近年来在我国兴起了一股研究陆架泥质沉积体的热潮,取得一大批重要成果。本文对我国最大的东海内陆架泥质沉积体的研究进展进行回顾,作为典型区域呈献给读者。东海内陆架泥质沉积区从长江口水下三角洲向南,沿闽浙近岸浅海一直延伸到台湾海峡中部,全长800km,宽约100km,面积约80000km2,相当于两个台湾岛的大小,实属我国乃至亚洲浅海规模最大(体积排第二)的楔式泥质沉积体和现代沉积区。该区中晚全新世沉积地层厚度较大,局部厚达40—80m,总体上呈近岸厚、向海方向逐渐变薄,一般在50—60m等深线、局部可达75m甚至90m等深线附近尖灭。该区泥质沉积物粒度较细,主要由黏土和粉砂组成(大于90%),砂含量很低(小于10%),黏土和粉砂含量在泥质沉积区外缘急剧降低,而砂含量突然增加。沉积物类型为粉砂质黏土和黏土质粉砂,外侧与黏土-粉砂-砂(混合沉积)或泥质砂为界。粒度分布南北有一定差异,北段(长江口外至瓯江口外)近岸较粗外侧较细,近岸为黏土质粉砂,外侧为粉砂质黏土;而南段(自瓯江口至台湾海峡北部)则相反;深入台湾海峡中部的远端泥质沉积也较粗,为黏土质粉砂。现代沉积速率从长江口水下三角洲至闽浙沿岸近海以及从近岸向外陆架方向逐渐降低,与地层厚度分布相一致。悬浮体浓度空间分布,尤其是冬季悬浮体的分布与沉积速率的分布基本一致,表明沉积物是从长江口沿闽浙近海向南和从近岸向海输运的。矿物、化学和环境磁学指标等均显示沉积物主要来自长江,老黄河对该区北部,台湾物质对南部有一定影响,闽浙沿岸河流在局部也有少量贡献。该泥质沉积体的形成与全新世中期约7.3ka BP以来持续高海面及相应的总体沉积动力过程密切相关,主要包括闽浙沿岸流将长江物质源源不断地向南输送和沉积过程、台湾暖流、上升流在其外侧的阻挡作用,以及下降流和穿刺锋的横向输运等动力控制因素。沉积物输运主要发生在冬季,冬季风导致海洋动力加强的作用功不可没,热带气旋-台风风暴对泥质体起到了一定助长与破坏的双重作用。由于该泥质沉积体的形成与季风和沿岸流的密切关系,在形成过程中打上了气候环境的烙印,是冬季风和夏季风演化记录的良好载体,近年来的研究成果很好地揭示了中晚全新世以来千年、百年、十年尺度甚至更高分辨率的气候演化历史及气候突变事件。该泥质沉积区对人类活动的响应也较敏感,自3.0ka BP以来对长江流域燃火变化以及历史上中国人口的几次大迁徙均显现在沉积记录中,特别是对近几十年,尤其是三峡水库蓄水以来,长江来沙的变化也有明显的响应。未来的研究需要进一步澄清泥质体形成发育过程不同阶段中长江、黄河、台湾、闽浙河流物质以及残留区物质的定量贡献及时空差异;深入了解人类活动的响应及环境记录研究;加强现代沉积动力过程的观测和精细的数值模拟研究,揭示泥质积区动力背景的空间差异性,这不仅是深化泥质沉积形成机制的需要,也可为古环境恢复提供科学支撑。     

The partial pressure of carbon dioxide and air-sea fluxes in the Changjiang River Estuary and adjacent Hangzhou Bay

The distributions of partial pressure of carbon dioxide (p CO2 ) in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water p CO2 ranged from 751-2 095 μatm (1 atm=101 325 Pa) in the inner estuary, 177-1 036 μatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface p CO2 behaved conservatively during the estuary mixing. In the inner estuary, surface p CO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest p CO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/(m2 d) [61 mmol/(m2 d) on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink.     

沉积物捕获器在海岸与陆架沉积动力研究中的应用:以罗源湾和台湾海峡为例

运用时间序列的沉积物捕获器对海岸与陆架海域沉降颗粒物进行采集,估算沉降通量,并运用多学科综合研究手段分析沉降颗粒物的来源、组成、时空变化及控制因素,可以为海岸与陆架沉积动力过程的研究提供新的研究手段。福建罗源湾的实验表明,夏季罗源湾潮下带小潮至中潮期间的沉降通量为133.20~256.18g/(m2·t);由中潮向大潮变化期间单个潮周期的沉降通量明显增大,台风过后的大潮期间的沉降通量为373.99~590.51g/(m2·t);台风显著影响期间的沉降通量为746.34g/(m2·t);粒度分析及水动力观测结果显示,观测期间罗源湾潮下带沉降颗粒物主要来源于海底沉积物的再悬浮。台湾海峡西北部内陆架海域的实验研究表明,该海域近底部悬浮颗粒物沉降通量最大值为13.34g/(m2·d),由小潮向中潮沉降通量逐渐增大,这主要是由于近底部温盐跃层层位上移,近底部垂向混合作用增强,致使底部再悬浮沉积物向上扩散,并最终被沉积物捕获器捕获。沉积物捕获器可以接收到再悬浮沉积物,结合底部边界层过程的观测研究,可以深入认识海底沉积物的侵蚀、沉降及埋藏过程,在研究海岸与陆架区沉积动力学、泥质区沉积记录的形成过程与保存潜力中扮演着十分重要的角色。     

2009年初夏长江口及毗邻海区表层浮游植物群落结构的色素表征

2009年6月对东海表层海水光合色素进行了高效液相色谱(HPLC)分析,通过藻类色素化学分类分析软件Chemical Taxonomy(CHEMTAX)获得了不同浮游植物对叶绿素a的贡献,研究了表层浮游植物群落结构的组成.结果表明:表层浮游植物的生物量与群落组成受温度、悬浮物质量浓度、营养盐等环境因素的影响,在水平分布...     

长江口及其邻近海域营养盐的分布特征和输送途径

根据黄海、东海的最新现场调查资料,探讨了长江口及其邻近海域营养盐分布特征与输送途径.调查结果表明,在长江口以东及其东北部海域终年存在一个范围很大的营养盐高值区.分析表明,这些营养盐主要来自长江冲淡水的扩展及苏北沿岸流的输送.此外,还获得了1998年长江流域特大洪水期间,迄今被观测到的长江冲淡水中营养盐的最大扩展范围.     

长江口及邻近海区营养盐结构与限制

通过研究长江口及邻近海域溶解无机氮(DIN=NO₃-+NO₂-+NH₄+)、磷酸盐(PO₄3-)、硅酸盐(SiO₃2-)所表征的营养盐区域结构特征及影响因素,在分析营养盐绝对限制情况的基础上,划分了潜在相对营养限制区域。结果表明,123°E以西近岸表层区域DIN/P比值全年均高于16,而Si/DIN除秋季外基本小于1,显示出长江冲淡水影响下"过量氮"的特征。春夏季河口锋面区(31°~32.5°N,122.5°~124°E)硅藻的大量生长可使DIN/P异常升高和Si/DIN异常降低。秋季研究区域北部DIN/P西低东高且Si/DIN西高东低是由于在高DIN、低PO₄3-的长江冲淡水影响下,近岸受相对低DIN、高SiO₃2-的苏北沿岸流南下入侵影响而被分割而成。冬季长江口门东北部存在的高DIN/P和低Si/DIN区则主要由于寡营养盐的黑潮水深入陆架,向东北输送的部分长江冲淡水和增强的苏北沿岸流共同作用造成DIN升高所致。利用Redfield比值进行了不同站位表层潜在相对营养限制情况的区分。近岸123°E以西受高DIN、SiO₃2-长江冲淡水影响,四季多呈现PO₄3-潜在相对限制,而在春夏季由于浮游植物的大量吸收PO₄3-,造成局部PO₄3-绝对限制及潜在相对限制。春夏季氮限(DIN潜在相对限制)一般发生在外海部分站位,但较为零散。秋季除了东南外海大部分站位外,受苏北沿岸流影响在长江口北部近岸也存在氮限。随着低DIN/P的黑潮表层水(KSW)的入侵加强,冬季外海氮限站位增多。硅限(SiO₃2-潜在相对限制)在夏季发生在赤潮高发区,而冬季南部存在较多硅限站位表明KSW中SiO₃2-相对较为缺乏。     

Benthic microbial biogeography along the continental shelf shaped by substrates from the Changjiang River plume

Coastal zones are active reactors of continental material including that transported by rivers via a series of microbiota-mediated reactions. Nevertheless, current knowledge of the ecology and functioning of the microbiota in coastal areas affected by large riverine inputs remains insufficient on a global scale. Here, an investigation on sediment microbial composition, including taxonomy and metabolic network, as well as their relationship with major benthic reaction substrates, namely carbon, n...     

入海泥沙的减少对长江口赤潮增加有贡献吗?

过去几十年来全球近海有害藻华（又称赤潮）发生频率持续增加。人类活动造成的河口-近海富营养化程度的加剧,被认为是导致全球有害藻华增加的主要原因。但是,富营养化程度的加剧可能不是全球有害藻华增加的惟一原因。河流入海的非营养盐类的其他物质通量变异（如泥沙）,也可能显著影响河口-近海的生物活动乃至赤潮的发生。过去40年来随着长江入海营养盐通量的增加,长江入海泥沙通量减少了70%。长期观测资料显示,由于泥沙减少使得长江口羽状流区光照条件显著改善,长江口浮游植物生物量最大值区已扩展至更低盐度的区域。此外,过去40年来长江口赤潮发生频率变化与长江入海泥沙通量变化呈现镜像关系,且二者呈显著的负相关关系。因此认为,长江入海泥沙的剧烈减少降低了羽状流区水体浊度,从而对长江口区赤潮频率的增加有一定贡献。     

Relationship between suspended sediments from the Changjiang Estuary and the evolution of the embayed muddy coast of Zhejiang Province

South of Hangzhou Bay, Zhejiang Province, exhibits an embayed muddy coastline, with the muddy beaches of embayments extending continuously seaward.The source of sediments on this coast presents an interesting problem to marine geologists and geomorphologists .The total annual load of sediments from the rivers of Zhejiang is only 12×106t.These materials affect only the area near the river mouths. The paper showed that the sediment along the coast of Zhejiang mainly comes from the Changjiang Estuary through analysing the time and space variations of suspended sediment, the features of sediment and the sedimentary transport.The Changjiang River is the largest river system in China, its sediment to the sea amounting to 468×106t. The sediment during summer transports mainly eastward, and is affected by the water body with high temperature, salinity and transparency; the winter season is the period with high sediment concentration. The sediment of the Changjiang Estuary transports together with the longshor