Heavy metals and phosphorus in tidal flat sediments of the Yangtze estuary

Concentrations of heavy metals (Cu, Pb, Zn, Cr and Cd), and phosphorous (P) were determined in surface tidal flat sediments of the Yangtze estuary and Shanghai coast. Results demonstrate that there were significant differences among the accumulation of the heavy metals in sediments, following the order: Zn > Cu > Cr > Pb > Cd. The spatial distribution and chemical forms of heavy metals in tidal flat sediments were closely related to the distribution of pollution resources (outlet of sewage) and the local sedimentary and hydrodynamic conditions. The dominated form of non-residual heavy metals is bound to Fe/Mn oxides, and the next form is bound to carbonates. Moreover, contents of total P in sediments range from 18.0 μmol.g-1 to 31.4 μmol.g-1 along the coastline, speciation of P in sediments was different, most of P in tidal flat sediments is associated with calcium phases (as Ca-P) similar to marine sediments.     

近期长江北支口门圆陀角附近潮滩地貌动态变化

圆陀角位于长江北支岸线与江苏海岸线的交会处,独特的互花米草潮滩、淤泥质光滩环境和复杂的河海沉积动力,决定了潮滩地貌对海洋环境变化的响应具有敏感性。由于大规模的围垦,圆陀角附近过去40年来海岸线向东推进了6km。根据2006年以来多次的野外调查和室内粒度与钻孔岩芯的¹³⁷Cs分析, 2006年以来圆陀角附近潮滩淤积明显加强,由¹³⁷Cs时标估算的互花米草滩多年平均沉积速率为2.3cm/a, 2006~2008年观测到的互花米草滩淤积速率>4cm/a,粉砂淤泥质光滩的淤积速率更高;圆陀角风景区内互花米草滩前缘陡坎在风暴潮影响下侵蚀后退,并因粉砂淤泥质光滩的快速淤长而消亡,圆陀角附近潮滩地貌动态是对人类围垦活动、风暴潮与潮汐海洋动力的综合响应,互花米草与光滩快速淤积是近期圆陀角附近潮滩地貌演化的主要特点。     

长江口拦门沙河段潮滩表层沉积物分布特征(英文)

Sediment samples with high spatial resolution (432 samples in total) and flow data were collected on the tidal flats in the mouth-bar region of the Yangtze Estuary. The data was collected in July 2005, July 2006 and May 2007. The samples were analyzed with a particle sizer, resulting in the sediment distribution. The grain sizes and related parameters were analyzed. The results were presented in a ternary diagram. The sediment mainly consisted of sand, silty sand, sandy silt, sand-silt-clay, silt and clayey silt. And sand skeletons and clay matrices were found. At Nanhui Shoal, silt skeletons could be identified as well. Furthermore, the results were discussed per shoal. Although some depth dependencies were found per shoal, no general relation was found. The results are as follows: sediment located at these tidal flats of the Yangtze Estuary was mainly composed of sand, silty sand and silt. The median grain size in sediment was relatively complex with a range from 2.5 φ to 8 φ. The distributions of sorting coefficients ranging from 1 to 2 were in agreement with median sizes. It was suggested that sediment of the tidal flats was coarser and better sorted or finer and worse sorted. The skewness in sediment distribution varied from 0.1 to 0.8. In addition, the distributions of sorting coefficient and skewness in sediment at Chongming Eastern Shoal, Hengsha Eastern Shoal and Jiuduan Shoal were of similar characteristics because there were closely positive correlated relationships among these parameters. However, due to the location difference between Nanhui Southern Shoal and Eastern Shoal, the values of sorting coefficient and skewness had relatively large distinctions. The tracks of sediment transport could be described based on the distributions of sediment, which might reveal sediment transport controlled by two dominant hydrodynamic factors of current and wave. It was appreciable that coarser sediment with lower sorted coefficient was affected by dominant ebb current action and intense wave action resulted from rapidly dissipated wave energy. Moreover, due to the effects of obstructed branches, guided current and broken wave actions of the Deep Water Channel Project, grain-size in sediment located at two sides of the groyne was of uneven distribution characteristics.     

近百年来长江口启东嘴潮滩沉积物质来源及定量估算

河流入海输沙是海岸稳定的重要物质基础。启东嘴潮滩位于长江北支口门,与江苏海岸线交汇,陆海相互作用强烈。利用电感耦合等离子体质谱仪测定了岩芯沉积物QDZ-1的地球化学元素。根据地球化学元素的分布特征和富集系数,分析了物源指示意义,表明启东嘴潮滩沉积物受到长江物质和南黄海物质的共同影响。基于地球化学元素的沉积物端元定量判识方法,对不同物质来源的贡献率进行了定量估算。在1930年前启东嘴潮滩沉积物主要来自长江的入海输沙,贡献率为68.1%,随着长江北支河槽的衰退,贡献率逐渐减少,在1930-1972年间为38.5%,到1972年后减少到17.5%。苏北沿岸流携带向南输运的南黄海物质,贡献率逐渐增加,在1930年前为27.1%,在1930-1972年间为55.6%,到1972年后增加到75.9%,成为启东嘴潮滩主要物质来源。沉积物来源的阶段性变化,在时间上与北支水动力的阶段性变化基本吻合。     

上海滨岸潮滩沉积物重金属元素的空间分布与累积

对上海滨岸潮滩沉积物重金属元素空间分布格局的系统分析表明,由于受多年来城市工业废水和生活污水沿直排、以及城市汽车尾气和工业粉尘干湿沉降的影响,本区潮滩表层沉积物中Ｃｕ、Ｚｎ、Ｃｒ、Ｐｂ等重金属元素的污染程度已相当严重。大型排污口附近滩地、不动力条件较弱的高潮滩部位、以及沉积物亚表层１０～３０ｃｍ深度是重金属累积并形成富集的主要部位,沿岸排污、水动力作用、大型工程活动、早期成岩作用、风暴潮等是影响本     

长江口潮滩沉积物－水界面无机氮交换通量

对长江口滨岸潮滩7个典型断面三态氮的界面交换通量进行了三年多的季节性连续观测,结果表明无机氮的界面交换行为存在复杂的空间分异和季节变化。NO^-₃-N和NH⁺₄-N的界面交换通量正负变化范围较大,分别介于-32.82~24.13 mmol.m^-2.d^-1和-18.45~10.65mmol.m^-2.d^-1之间;而NOsup>-₂-N的界面交换通量很小,仅为-1.15~2.82 mmol.m^-2.d^-1。NO^-₃-N的界面交换具有明显的上下游季节性时空分异特征,而NH⁺₄-N的界面交换则表现为南北岸季节性时空分异现象。盐度是控制长江口滨岸潮滩NH⁺₄-N界面交换行为的主要因素,而沉积物粒度、水体 NO^-₃-N浓度、沉积物有机质含量、水温和溶解氧含量则以不同的组合方式,共同制约着 NO^-₃-N在潮滩界面交换的时空分异格局。     

长江口拦门沙河段潮滩表层沉积物分布特征

基于2005年7月及2007年5月在长江订拦门沙河段崇明东滩、横沙东滩(浅滩)、九段沙以及南汇边滩等四大潮滩的水下滩地采集的大面积、高密度表层沉积物以及实测水文资料,对拦门沙河段潮滩表层沉积物颗粒度、参数、组成、类型以及分布特征进行分析,并在此基础上探讨影响沉积物分布的主要动力因子.结果表明:长江河口四大潮滩表层沉积物主要由砂、粉砂质砂和粘土质粉砂三种类型组成.沉积物中值粒径分布比较复杂,介于2.5～8ψ之间;沉积物分选系数集中于1～2左右,其分布与中值粒径具有一致性,其中物质组成相对较粗的颗粒分选性较好而较细的颗粒分选性较差:偏态与峰态跨度较大,分别介于0.1-0.8与1-4不等.崇明东滩、横沙东滩(浅滩)和九段沙的沉积物分选系数、偏态和峰态的分布具有一致性,三者相关性较强;南汇边滩的沉积物分选性、偏态及峰态值则因南滩与东滩所处位置差异而有较大差别.此外,河口潮滩表层沉积物分布显示泥沙输移的结果,其主要水动力因子包括潮流和波浪控制的泥沙输移:在受落潮优势流作用的地区普遍粗于涨潮优势流作用的地区;在波浪动力强、波能释放的地区沉积物普遍较粗且分选性较好:深水航道工程的堵汉、导流、破水波作用明显,使得导堤两侧的表层沉积物粒度出现粗细分布不均的特点.     

崇明东滩海三棱藨草生长期沉积物有机碳含量变化

The investigations on the organic carbon （OC） of core sediments were carried out in Chongming east tidal fiat （CM） during Scirpus mariqueter growing stage （from April to December 2004） in Yangtze Estuary. The Yangtze River annually transports a runoff discharge of 30,000 m^3/s, carrying about 480 million tons of sediments to the estuarine and coastal area, which formed a great OC pool. In the sampling spots, seven quadrats of 50 cm × 50 cm and five sediments cores of 20 cm deep （40 cm deep in December） were randomly established in order to collect vegetations and core sediments samples during the low tide each month except November. After pretreatment, the core sediments were sieved and their OC contents were measured according to the potassium dichromate method. The results show that the higher surface sediment OC content in summer comes from allochthonous terrigenous particle settlements on the Chongming east middle tidal fiat S. mariqueter zone. In autumn and winter, the decomposing of the defoliated S. mariqueter increases the surface sediments OC content. Settling velocity, sediment temperature and S. mariqueter growth are the main factors that can control the sediment carbon content. Summer is the “carbon losing” period of the tidal fiat sediments, while from September, it changes into the “carbon accumulating” period of sediment OC pool because of the decomposing of dead S. mariqueter community in the sediments. From this alternation of “carbon losing” period and “carbon accumulating” period, we conclude that carbon in the OC pool of the middle tidal fiat S. mariqueter zone sediments mainly comes from the atmospheric carbon rooted by S. mariqueter photosynthesis.     

The variation of sediments organic carbon content in Chongming east tidal flat during Scirpus mariqueter growing stage

The investigations on the organic carbon (OC) of core sediments were carried out in Chongming east tidal flat (CM) during Scirpus mariqueter growing stage (from April to December 2004) in Yangtze Estuary. The Yangtze River annually transports a runoff discharge of 30,000 m3/s, carrying about 480 million tons of sediments to the estuarine and coastal area, which formed a great OC pool. In the sampling spots, seven quadrats of 50 cm × 50 cm and five sediments cores of 20 cm deep (40 cm deep in December) were randomly established in order to collect vegetations and core sediments samples during the low tide each month except November. After pretreatment, the core sediments were sieved and their OC contents were measured according to the potassium dichromate method. The results show that the higher surface sediment OC content in summer comes from allochthonous terrigenous particle settlements on the Chongming east middle tidal flat S. mariqueter zone. In autumn and winter, the decomposing of the defoliated S. mariqueter increases the surface sediments OC content. Settling velocity, sediment temperature and S. mariqueter growth are the main factors that can control the sediment carbon content. Summer is the "carbon losing" period of the tidal flat sediments, while from September, it changes into the "carbon accumulating" period of sediment OC pool because of the decomposing of dead S. mariqueter community in the sediments. From this alternation of "carbon losing" period and "carbon accumulating" period, we conclude that carbon in the OC pool of the middle tidal flat S. mariqueter zone sediments mainly comes from the atmospheric carbon rooted by S. mariqueter photosynthesis.     

长江北支口门圆陀角附近潮滩沉积物元素地球化学特征及其环境指示意义

圆陀角地处长江北支与江苏海岸的交汇处,发育了典型的粉砂淤泥质潮滩,潮滩沉积物元素可记录海岸环境变化的信息。在圆陀角附近潮滩采集了长度为218 cm的YY孔岩芯,常量与微量元素分析结果显示,岩芯沉积物平均粒径与大多数元素之间相关性好,“粒控效应”特征明显。除Ca、Na、Ti、P、Sr外,岩芯大部分元素含量自下向上呈现由低变高再变低的趋势,并在岩芯132 cm深度出现最大值。根据圆陀角附近海岸沙嘴长江北支变迁的证据,苏北岸外海域是长江北支的重要泥沙来源;粒度和粘土校正后的元素含量呈自下而上由低变高的趋势。邻近区域沉积物元素富集系数分析显示,在1956年前后,圆陀角附近潮滩沉积物发生了较大的变化,1956年以前的主要来源于长江,1956年以后演变为主要来源于南黄海辐射沙洲南翼。     

长江中下游浅水湖泊表层沉积物潜在可交换性磷研究

利用无限稀释外推法 (IDE法 )和Hieltjes与Lijklema提出的H-L法对长江中下游浅水湖泊表层沉积物中可交换性磷进行测定,研究了IDE法测定的潜在可交换性磷 (IDE-P )与H-L法使用NH₄Cl测定的氯化铵磷 (NH₄Cl-P )在不同污染程度沉积物中的分布规律及二者关系,并对IDE-P和NH₄Cl-P与沉积物土壤测试磷 (STP)、磷吸附饱和度 (DPS)、总磷 (TP)和有机质关系进行讨论。结果表明,沉积物IDE-P和NH₄Cl-P分布遵循重污染沉积物>污染较轻沉积物的规律,IDE-P含量高于NH₄Cl-P含量;不同沉积物的(NH₄Cl-P/IDE-P)%变化较大;IDE-P和NH₄Cl-P与STP、DPS、总磷和有机质的相关性较好。     

近代以来江苏沿海滩涂围垦历史演变研究

近百年来江苏沿海进行了大规模的滩涂围垦开发。本研究评估了近代以来江苏沿海滩涂围垦历史演变情况,分析其演变机理。研究搜集整理了清末至今多种历史地形图、地方志、遥感资料,利用统计分析以及空间分析,定量地揭示近百年来江苏沿海围垦时空变化,并简要分析变化背后的机理。研究结果表明：（1）在围垦的时间分布上,不同时期的历史围垦程度不同,其中民国时期1910 年代和解放以后的1950 年代的围垦规模分别为解放前和解放后的两个围垦高峰时期;（2）在围垦的空间分布上,总的来说,盐城市围垦面积最大,总量占全省总围垦面积近70%,南通、连云港市相对较少,而沿海三市围垦面积排名前五名的分别是大丰市、射阳县、连云区、响水县、如东县;（3）从围垦特点看,空间缓冲区分析显示历史上江苏沿海围垦多为鱼鳞似的圈围,用途则以农业生产、水产养殖、国营盐场为主,工业用地、港口建设用地大大不足,用地综合效益不高。     

Similarities between Yangshan Harbor area and the Yangtze estuary

By analysis of published papers on the Yangtze estuary and hydrological and sediments data in Yangshan Harbor area, many similarities are found between Yangshan Harbor area and the Yangtze estuary. These similarities include the phenomenon of stagnating flow areas, the distributive characteristics of the highest suspended sediment concentration areas, superficial sediments and shoal bars. The stagnating flow area is the major similarity which causes other similarities. These similarities indicate that: 1) Turbidity Maximum and mouth bars in estuaries are mainly caused by the hydraulic balance of stagnating flow areas of estuaries; 2) The stagnating sand area of sands caused by stagnating flow area often locates on the narrower side of the stagnating flow area; 3) The location (or shape) of fine sediments area caused by stagnating flow area reflects the location (or shape) of the stagnating flow area. Both Yangshan Harbor area and the Yangtze estuary are the important developmental areas in the future (man-made similarity). In-depth studies on these similarities between Yangshan Harbor area and the Yangtze estuary will have momentous theoretical and practical significance.     

潮滩围垦对海岸环境的影响研究进展

潮滩围垦是沿海国家拓展陆域, 缓解人地矛盾的最主要方式之一。潮滩围垦通过对潮滩高 程、水沙动力条件、沉积物特征等多种环境因子的改变, 促进生物演替, 并通过垦区土地的人为利 用, 对海岸环境演变产生重要影响。文章从围垦工程对水沙环境的影响、围垦对海岸带物质循环 的影响、围垦对潮滩生物生态学的影响和盐沼恢复与生态重建等4 方面探讨了不同学科学者对 围垦环境影响的主要研究进展及存在的问题, 并指出应加强多学科合作的综合研究, 探讨潮滩围 垦对海岸环境的影响机制, 以寻求兼顾围垦土地需求与海岸带生态保护的持续发展之路。     

长江来沙锐减与海岸滩涂资源的危机

利用小波分析方法对1951~2004年大通站系列水、沙和流域降水资料进行周期性和趋势性分析,利用Arc-GIS软件对长江三角洲海图进行滩涂面积计算和冲淤剖面分析,并于2002年5月~2005年7月在长江三角洲前缘的南汇岸段进行逐日潮滩高程测量,以进行三峡水库蓄水前后滩面冲淤的对比。结果表明：尽管气候变化导致流域平均降水量以及大通径流量和输沙率存在2~3年和8~9年的波动周期 (P < 0.05),但大通输沙率从1960年代末开始出现明显的下降趋势 (P< 0.001),三峡工程运行后的2003年 (6月开始蓄水) 和2004年连续2年创历史新低,流域水库的修建是导致这一下降趋势的根本原因。长江来沙量的锐减正在导致三角洲前缘滩涂从淤涨向侵蚀转化。预测认为：流域人类活动还将继续导致长江入海泥沙量的下降,今后几十年的大通输沙率将从目前的 1.5×10⁸ ~2×10⁸ t/a下降到1×10⁸ t/a左右;泛长江三角洲海岸滩涂资源将面临严峻挑战。     

Similarities between Yangshan Harbor area and the Yangtze estuary

By analysis of published papers on the Yangtze estuary and hydrological and sediments data in Yangshan Harbor area, many similarities are found between Yangshan Harbor area and the Yangtze estuary. These similarities include the phenomenon of stagnating flow areas, the distributive characteristics of the highest suspended sediment concentration areas, superficial sediments and shoal bars. The stagnating flow area is the major similarity which causes other similarities. These similarities indicate that: 1) Turbidity Maximum and mouth bars in estuaries are mainly caused by the hydraulic balance of stagnating flow areas of estuaries; 2) The stagnating sand area of sands caused by stagnating flow area often locates on the narrower side of the stagnating flow area; 3) The location (or shape) of fine sediments area caused by stagnating flow area reflects the location (or shape) of the stagnating flow area. Both Yangshan Harbor area and the Yangtze estuary are the important developmental areas in the future (man-made similarity). In-depth studies on these similarities between Yangshan Harbor area and the Yangtze estuary will have momentous theoretical and practical significance.     

长江北支口门圆陀角附近潮滩沉积物重金属来源及污染评价

基于圆陀角附近潮滩YY孔岩芯重金属(Co、Cr、Cu、Mn、Ni、V、Zn)富集系数和人为贡献率、地累积指数和潜在生态风险系数,讨论了圆陀角附近潮滩重金属来源及污染。结果表明,重金属Co、V平均含量显著高于背景值。除Cr 是自然来源外,其它6 种重金属受自然和人为来源的影响,且以自然来源为主。7 种重金属总体无污染,仅Co、Cu、V和Zn在岩芯132 cm处出现无污染至中度污染。7 种重金属潜在生态危害属轻微水平。值得关注的是,1997 年之后,重金属Co、Cr、Mn、V、Zn地累积指数和潜在生态风险系数均有增加的趋势。     

Temporal and spatial changes of suspended sediment concentration and resuspension in the Yangtze River estuary

A detailed analysis of suspended sediment concentration (SSC) variations over a year period is presented using the data from 8 stations in the Yangtze River estuary and its adjacent waters, together with a discussion of the hydrodynamic regimes of the estuary. Spatially, the SSC from Xuliujing downwards to Hangzhou Bay increases almost constantly, and the suspended sediment in the inner estuary shows higher concentration in summer than in winter, while in the outer estuary it shows higher concentration in winter than in summer, and the magnitude is greater in the outer estuary than in the inner estuary, greater in the Hangzhou Bay than in the Yangtze River estuary. The sediments discharged by the Yangtze River into the sea are resuspended by marine dynamics included tidal currents and wind waves. Temporally, the SSC shows a pronounced neap-spring tidal cycle and seasonal variations. Furthermore, through the analysis of dynamic mechanism, it is concluded that wave and tidal current are two predominant factors of sediment resuspension and control the distribution and changes of SSC, in which tidal currents control neap-spring tidal cycles, and wind waves control seasonal variations. The ratio between river discharge and marine dynamics controls spatial distribution of SSC.     

长江口水域悬沙浓度时空变化与泥沙再悬浮

A detailed analysis of suspended sediment concentration (SSC) variations over a year period is presented using the data from 8 stations in the Yangtze River estuary and its adjacent waters, together with a discussion of the hydrodynamic regimes of the estuary. Spatially, the SSC from Xuliujing downwards to Hangzhou Bay increases almost constantly, and the suspended sediment in the inner estuary shows higher concentration in summer than in winter, while in the outer estuary it shows higher concentration in winter than in summer, and the magnitude is greater in the outer estuary than in the inner estuary, greater in the Hangzhou Bay than in the Yangtze River estuary. The sediments discharged by the Yangtze River into the sea are resuspended by marine dynamics included tidal currents and wind waves. Temporally, the SSC shows a pronounced neap-spring tidal cycle and seasonal variations. Furthermore, through the analysis of dynamic mechanism, it is concluded that wave and tidal current are two predominant factors of sediment resuspension and control the distribution and changes of SSC, in which tidal currents control neap-spring tidal cycles, and wind waves control seasonal variations. The ratio between river discharge and marine dynamics controls soatial distribution of SSC.