共查询到17条相似文献，搜索用时 578 毫秒
1.
杭州湾南岸互花米草生物海岸表层沉积物粒度分析 总被引：2，自引：0，他引：2
互花米草盐沼可显著改变潮滩的水动力条件、沉积特征和地貌演化过程。分析杭州湾南岸互花米草滩内外表层沉积物的粒度特征,互花米草生物海岸沉积物包括粘土质粉砂、粉砂、粉砂质砂和砂质粉砂4类,由东向西各断面草滩内、外沉积物中值粒径逐渐变粗,分选性变好;从低潮滩向高潮滩沉积物的中值粒径Φ值增大,分选性变差。互花米草滩外边界处形成沉积物中值粒径及分选系数的突变点。杭州湾南岸生物海岸表层沉积物以跃移质为主,悬移质次之,推移质最少;由海向岸悬移质、跃移质和推移质均有变细趋势。 相似文献
2.
江苏王港盐沼的现代沉积速率 总被引：35，自引：0，他引：35
江苏海岸湿地总面积超过5000km^2，但围垦活动的加剧使盐沼湿地面积迅速减少；为了达到海岸防护、保滩促淤的目的，先后引种了大米草和互花米草。通过采集江苏王港潮滩盐沼湿地9处柱状样和挖取探槽剖面，以及对沉积剖面样品进行^210Pb和^137Cs测年分析，探讨了^210Pb的本底及影响^210Pb富集的因素，估算了王港盐沼湿地的现代沉积速率。王港潮滩盐沼沉积物对^210Pb的吸附作用较弱；受风暴潮、生物扰动、物源变化及实验误差等因素的影响，在^210Pbex剖面上出现了数据异常点，将这些数据点剔除后计算得到的沉积速率为33cm yr^-1，^137Cs测年显示，该地区1963年以来的平均沉积速率3．1cm yr^-1，与^210Pb法及前人研究结果相一致。根据一个典型剖面的^137Cs测年数据分析，王港潮滩盐沼的沉积过程根据地貌特征的不同可分3个阶段，大米草覆盖阶段滩面高程迅速增加，互花米草的生长提高了滩面淤积速率。 相似文献
3.
互花米草引种对苏北潮滩湿地 TOC 、TN和TP分布的影响 总被引：5，自引：0，他引：5
分析了TOC、TN和TP在苏北潮滩湿地不同生态带沉积物和植被中的分布状况,结果表明:TOC和TN的水平和垂向平均含量以互花米草滩为最高,其次分别为盐蒿滩、芦苇滩和光滩。TP的平均含量以光滩为最高,依次由海向陆逐渐减小。在生物量最大期间(秋季),单位面积上互花米草体内TOC、TN和TP的累积量远大于盐蒿和芦苇。互花米草主要通过以下4个方面对研究区潮滩湿地TOC、TN和TP的分布产生影响:(1)互花米草滩面较高的沉积速率;(2)互花米草对整个潮滩湿地不同植被分布格局的改变;(3)互花米草有着高生产力以及巨大的地下生物量;(4)互花米草的生长特性使其在生长过程中对磷的需求量很大。 相似文献
4.
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。 相似文献
5.
人类活动对苏北潮滩发育的影响 总被引：14，自引：5，他引：9
江苏北部潮滩宽阔而平坦,历史上就是人类活动比较频繁的地区。随着对潮滩开发利用强度和深度的增加,人类对潮滩发育的影响越来越显著。潮滩剖面自然发育的均衡形态为上凸型;潮滩被围垦并建堤后,改变了原有的水沙动态平衡关系,潮滩剖面形态发生了调整,海堤附近的潮水沟则不断被淤积。大米草和互花米草等植被的引种改变了潮滩生态结构,由于植被能降低水流流速和波浪能量,起到捕捉沉积物的作用,因此能增加潮间带滩面的淤积速率,改变潮滩分带结构;此外,植被的存在还影响到滩面潮水沟的形态。港口工程的建设改变了沉积物的输运方向。 相似文献
6.
基于影像间潮滩地形修正的海岸线监测研究——以黄河三角洲为例 总被引：6，自引：0，他引：6
针对潮滩环境中潮汐和坡度变化对海岸线变化监测的影响,提出一种通过两景影像计算潮滩坡降进而准确获得海岸线的方法,并利用坡降值估算潮滩体积。以岸线变化较剧烈的黄河三角洲南部的甜水沟口至小清河口的粉砂淤泥质潮滩为例进行应用研究。结合遥感影像、实测固定断面数据和水深测量数据分析表明,影像间的潮差对坡降估算值虽有较大影响,但选择合适潮位估算潮滩坡降是可行的,估算坡降的最小相对误差可达0.2%,均方根误差小于实测坡降一个数量级。1973-2009 年甜水沟口至小清河口14 个年份的岸线变化分析显示,黄河改道对本区的直接淤积影响在甜水沟向南3 km范围内,最大淤积区位于甜水沟口附近,年均淤积率31 m/a,而后在1989-2002 年海区南部出现较大幅度淤积,主要为黄河入海水沙直接或间接淤积造成的;研究时段内岸滩总体演化趋势为蚀退,最大年均蚀退速率51 m/a,黄河改道造成的海洋动力变化是影响本区海岸冲刷的主要因素。验证表明,本文方法计算的潮滩体积用于指示海滩冲淤变迁是合理可行的。 相似文献
7.
江苏中部海岸互花米草扩展对滩涂围垦的响应 总被引：1，自引：0，他引：1
根据2001-2013年遥感影像和野外观测数据,对江苏中部海岸互花米草(Spartina alterniflora Loisel)在滩涂围垦期间的扩展过程进行定量化分析。结果显示：2001-2013年互花米草扩展对围垦的响应大体分为三个阶段：2001-2007年,海堤外米草面积较大,每年新增米草面积及米草年扩展率均和新增围垦面积变化同步,且相关性显著;2008-2010年,海堤外米草面积较小,但米草年扩展率仍然较高;2011-2013年,随着围垦的持续进行,米草扩展进入稳定期。因此,互花米草扩展对于滩涂围垦的不同速率和阶段具有不同的响应。若围垦时保留足够宽度的堤前米草,则围垦可以提高米草的年扩展率,其机理是互花米草种子产量和前缘淤积环境是影响米草扩展的主要因素,而围垦对这两方面都有影响。在后期滩涂围垦时,应保证堤外米草宽度在0.9~1 km之间,实现土地资源的可持续利用。 相似文献
8.
盐沼前缘陡坎是潮滩环境中盐沼与粉砂—淤泥质光滩交界处的独特地貌形态,研究其形成过程与机理有助于理解盐沼湿地对潮滩发育及其稳定性的影响。根据江苏中部海岸盐城自然保护区核心岸段互花米草盐沼前缘陡坎形态参数（凹槽长度、凹槽宽度和陡坎高度）的分析,发现不同的形态参数组合对应于不同的陡坎演化阶段。根据陡坎形态特征差异,可将盐沼前缘陡坎韵律性形态发育过程分为三个阶段,而这三阶段的交替旋回过程与近岸波向的季节性变化有关。陡坎处的地貌特征与前缘光滩的沉积物特征表明陡坎形态特征形成与波浪作用有关,且显著的陡坎韵律性形态能够部分地应用边缘波理论来解释。 相似文献
9.
锦州湾滩地动力地貌特征及其冲淤变化 总被引：1，自引：0，他引：1
本文阐述了锦州湾滩地动力地貌特征,海滩剖面形变,潮滩微地貌类型与横向分带性;并采用潮滩剖面重复水准测量、新老海图对比和210pb沉积速率测定等方法着重讨论了潮间浅滩和水下浅滩的冲淤变化。新老海图对比值为4-6mm/a,210pb沉积速率测定为1-5mm/a,湾内泥沙输沙量估算为2-4mm/a,三个量值基本接近。 相似文献
10.
互花米草盐沼潮沟地貌特征 总被引：18，自引：1，他引：17
互花米草是我国从国外引进的能在淤泥质潮滩的高潮带下部和中潮带上部生长的禾木科植物,由于其植株高大、群落盖度高、根系发达等生物学特性,其对潮流动力特征有显著的影响。本文通过对江苏省东台市笆斗垦区外互花米草盐沼地的潮沟形态调查,发现互花米草盐沼潮沟具有以下一些特征:潮沟密度大,可达50km/km2以上;潮沟的宽深比小,大多在8以下;沿岸堤发育,且多呈不对称状;一级主潮沟与主潮沟接头处普遍呈逆弧形;盐沼外侧边缘发育有明显的陡坎冲沟。分析认为这些特征主要与互花米草发达的根系和致密的植株等生物学特性有关,发达的根系增加了盐沼滩面的稳定性,而互花米草高大的植株增加了对潮水运动的阻力,提高了滩面落潮水的归槽水位,改变了潮流的泥沙沉积地点和涨、落潮流的流向,从而形成比较特别的互花米草盐沼潮沟特征。 相似文献
11.
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 总被引：1，自引：1，他引：0
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。 相似文献
12.
长江口盐沼土壤有机质更新特征的滩面趋势 总被引：1，自引：0，他引：1
Characteristics and tidal flat trends of soil organic matter （SOM） turnover were studied for the Chongmingdongtan Salt Marsh in the Yangtze River estuary, based on analyses of stable carbon isotope composition （δ^13C）, grain sizes and contents of particulate organic carbon （POC）, total nitrogen （TN） and inorganic carbon （TIC） for three cores excavated from high tidal flat, middle tidal flat and bare flat. Results demonstrate that correlations between soil POC contents and δ^13C values of the salt marsh cores were similar to those between soil organic carbon （SOC） contents and δ^13C values of the upper soil layers of mountainous soil profiles with different altitudes. SOM of salt marsh was generally younger than 100 years, and originated mainly from topsoil erosions in catchments of the Yangtze River. Correlations of TN content with C/N ratio, POC content with TIC content and POC content with δ^13C values for the cores suggest that turnover degrees of SOM from the salt marsh are overall low, and trends of SOM turnover are clear from the bare flat to the high tidal flat. Bare flat samples show characteristics of original sediments, with minor SOM turnover. Turnover processes of SOM have occurred and are discernable in the high and middle tidal flats, and the mixing degrees of SOM compartments with different turnover rates increase with evolution of the muddy tidal flat. The exclusive strata structure of alternate muddy laminae and silty laminae originated from dynamic depositional processes on muddy tidal flat was a great obstacle to vertical migration of dissolved materials, and SOM turnover was then constrained. The muddy tidal flat processes exerted direct influences on sequestration and turnover of SOM in the salt marsh, and had great constraints on the spatial and temporal characteristics of SOM turnover of the Chongmingdongtan Salt Marsh in the Yangtze River estuary. 相似文献
13.
长江口盐沼土壤有机质更新特征的滩面趋势 总被引：9，自引：0，他引：9
通过对长江口崇明东滩高潮滩、中潮滩以及光滩柱状样的有机元素(C、N)含量与碳稳定同位素组成(δ13C)、粒度组成等的测定,研究盐沼土壤有机质更新特征及其滩面趋势.结果表明,长江口盐沼土壤POC-δ13C相关特征与山地土壤剖面上部土层的基本类似,盐沼土壤有机质主要源于长江流域表层土壤,有机质年龄不足100年.不同高程柱样TN-C/N、POC-TIC与POC-δ13C关系特征表明盐沼土壤有机质更新程度普遍较低,有机质更新特征呈明显的滩面变化趋势.光滩有机质基本反映沉积母质特征,更新程度极低;中、高潮滩有机质更新作用已经发生,随着滩面演变,处于不同更新阶段的有机质组分混杂程度提高.盐沼滩面过程塑造垂向沉积层序,层序中独特的沙、泥纹层构造导致物质上下运移困难,有机质更新作用受到抑制.盐沼滩面过程直接影响有机质的累积与更新,对于有机质更新的时空特征具有显著制约. 相似文献
14.
Coastal salt-marshes represent an important coastal wetland system. The total area of coastal wetlands exceeds 5000 km2 in Jiangsu Province, China, but it is decreasing rapidly in response to the intense reclamation activities and coastal erosion along a part of the coastline. Hence, two types of plants, Spartina angelica and Spartina alterniflora, were introduced successively into the Jiangsu coastal areas, in order to protect the coastline from erosion and to increase the accumulation rate. Pb-210 and Cs-137 analyses were carried out for sediment samples from the salt-marshes of Wanggang to determine the sedimentation rate, on the basis of an evaluation of the background activity values and the factors affecting the enrichment of Pb-210. Analysis of a typical sediment column of the tidal flat shows that there is weak absorption of Pb-210 in the silt-dominated sediment. Because of the influences of factors such as storm events, bioturbation, material sources and analytical error, some abnormal data points appear in the Pb-210 record. After ignoring these data the calculated sedimentation rate was 3.3 cm yr-1 on average. Based upon analysis of the Cs-137 dating, the rate since 1963 was 3.1 cm yr-1 on average, similar to the data by Pb-210 dating and the previous studies. The dating results show that there were three stages of sedimentation, with the most rapid accretion being taking place after Spartina angelica was introduced into the area. The study also shows that at the stage of Spartina alterniflora growth, the accretion rate was higher than on the flat surface with the same elevation without the cover of this plant. 相似文献
15.
Sedimentation rates in the Wanggang salt marshes, Jiangsu 总被引：1，自引：0，他引：1
WANGAijun GAOShu JIAJianjun PANShaoming 《地理学报(英文版)》2005,15(2):199-209
1 IntroductionLand-ocean interaction in coastalzone is one of the key m atters of the International G eosphereand Biosphere Program (IG BP). The key problem s of the second phase in the next decadeinclude the m aterial cycle, the system evolution process … 相似文献
16.
Coastal salt-marshes represent an important coastal wetland system. The total area of coastal wetlands exceeds 5000 km2 in Jiangsu Province, China, but it is decreasing rapidly in response to the intense reclamation activities and coastal erosion along a part of the coastline. Hence, two types of plants, Spartina angelica and Spartina alterniflora, were introduced successively into the Jiangsu coastal areas, in order to protect the coastline from erosion and to increase the accumulation rate. Pb-210 and Cs-137 analyses were carried out for sediment samples from the salt-marshes of Wanggang to determine the sedimentation rate, on the basis of an evaluation of the background activity values and the factors affecting the enrichment of Pb-210. Analysis of a typical sediment column of the tidal flat shows that there is weak absorption of Pb-210 in the silt-dominated sediment. Because of the influences of factors such as storm events, bioturbation, material sources and analytical error, some abnormal data points appear in the Pb-210 record. After ignoring these data the calculated sedimentation rate was 3.3 cm yr-1 on average. Based upon analysis of the Cs-137 dating, the rate since 1963 was 3.1 cm yr-1 on average, similar to the data by Pb-210 dating and the previous studies. The dating results show that there were three stages of sedimentation, with the most rapid accretion being taking place after Spartina angelica was introduced into the area. The study also shows that at the stage of Spartina alterniflora growth, the accretion rate was higher than on the flat surface with the same elevation without the cover of this plant. 相似文献
17.
Seven cores were collected from different sediment zones of tidal flats at Xinyanggang in north Jiangsu province in August
2007. Sediment grain-size distribution and radioisotopes of 137Cs and 210Pb analysis were carried out for these cores. Sediment rates of the cores and radioisotopes distribution in surface sediment
in different zones of the tidal flat were calculated from the 137Cs and 210Pb activities in sediments cores. The results indicated that each tidal zone had experienced different evolution phases, hydrological
dynamics in the tidal flats made the grain-size of the surface sediment change gradually. 137Cs and 210Pb activities on the superficial layer of the cores varied spatially and the reason was discussed. On tidal flats, the fluctuation
of 137Cs and 210Pb activities in the cores reflected the special sedimentary characteristics. Vegetation affects the grain-size distribution
and the vertical profiles of 137Cs and 210Pb in the upper depths. 137Cs and 210Pb chronology got the comparable average sediment rates on the tidal flat. The characteristics of 137Cs and 210Pb in the cores reflected various depositional dynamical environments in different tidal zones and gave information on the
different evolvement phases of the tidal zones. Based on the information of grain-size distribution, texture of the cores,
sediment rates and topography, the evolution lines of the tidal flat were reconstructed. 相似文献