Provenance analysis of surface sediments in the Holocene mud area of the southern coastal waters off Shandong Peninsula,China

The sedimentary record of mud areas is an important carrier of information on the Holocene evolution of marine environments. Based on fine interpretations of the shallow stratigraphic section data, a small mud deposit area has been found in the southern coastal waters off Shandong Peninsula. This mud area is mainly distributed in coastal waters north of Laoshantou to the vicinity of Rushan Estuary. Overall, it is parallel to the coastline and spreads in a banded pattern, gradually thinning from offshore to the sea. The isopach map of depth distribution is parallel with the shoreline, and the depocenter lies in coastal waters of the Aoshan Bay where the maximum thickness is up to 22.5 m. Accelerator mass spectrometry（AMS） ^（14）C dating shows that the mud area was formed in the Holocene. The test data of surface sediments from the mud area, including particle size, mineral characteristics, and rare earth element contents, are used in comparisons with the composition of materials from the major surrounding medium and small rivers flowing into the sea and the Huanghe（Yellow） River. In this paper, the sedimentary characteristics and provenance of the mud deposit area are discussed. The results show that the formation of this mud area resulted from the joint action of the Huanghe River and surrounding rivers flowing into the sea.

The difference analysis of physical-mechanical properties of sediments in the central South Yellow Sea and Zhe-Min coastal area in China

The difference analysis of physical-mechanical properties of muddy sediments is made in the central South Yellow Sea and the Zhe-Min（Zhejiang Province to Fujian Province of China） coastal area. The results show that sediments in the two regions are both dominated by mud. There are perfect negative power function correlations between the water content and the density, the compression coefficient and the compression modulus; a good positive power function correlation between the liquid limit and the plastic limit, a perfect positive linear correlation between the water content and the void ratio, and a perfect polynomial function correlation between the miniature vane shear strength and the pocket penetration resistance. In general, compared with sediments in the Zhe-Min coastal area, sediments in the central South Yellow Sea possess high water content, high void ratio,low density, high plasticity, high compressibility, low shear strength. The causes of the differences between physical-mechanical properties of sediments are analyzed from the topographic features, material sources,hydrodynamic conditions, deposition rate, and material composition. Compared with the Zhe-Min coastal area,the central South Yellow Sea is far from the Mainland and low-lying; has poor hydrodynamic condition; the materials diffused to the area are less and dominated by fine clay, have the high content of smectite and organic matters. These factors lead to sediments of the central South Yellow Sea has the higher water content, the higher plasticity, the lower density, and the lower strength than sediments in the Zhe-Min coastal area.

Distribution characteristics of wave energy in the Zhe-Min coastal area

A 10-year(2003–2012)hindcast was conducted to study the wave field in the Zhe-Min coastal area(Key Area OE-W2)located off Zhejiang and Fujian provinces of China.Forced by the wind field from a weather research and forecasting model(WRF),high-resolution wave modelling using the SWAN was carried out in the study area.The simulated wave fields show a good agreement with observations.Using the simulation results,we conducted statistical analysis of wave power density in terms of spatial distribution and temporal variation.The effective duration of wave energy in the sea area was discussed,and the stability of wave energy was evaluated using the coefficient of variation of wave power density.Results indicate that the wave energy resource in the study area was about 4.11×10^(6) kW.The distribution of wave energy tends to increase from the north(off Zhejiang coast)to the south(off Fujian coast),and from near-shore area to the open sea.The sea areas with wave power density greater than 2 kW/m are mostly distributed seaward of the 10-m isobath,and the contours of the wave power density are almost parallel to the shoreline.The sea areas around the islands that are far from the mainland are rich in wave energy,usually more than 6 kW/m,and therefore are of obvious advantages in planning wave energy development and utilization.The effective duration of wave energy in the offshore area shows an increasing trend from north(off Zhejiang coast)to south(off Fujian coast),with values of∼3500 h in the north and∼4450 h in the south.The coefficient of variation of wave energy in this region is mostly in the range of 1.5–3.0,and gradually decreases from the north to the south,suggesting that the wave energy in the south is more stable than that in the north.

Upwelling and anthropogenic forcing on phytoplankton productivity and community structure changes in the Zhejiang coastal area over the last 100 years

Phytoplankton productivity and community structure in marginal seas have been altered significantly during the past three decades, but it is still a challenge to distinguish the forcing mechanisms between climate change and anthropogenic activities. High time-resolution biomarker records of two 210Pb-dated sediment cores（#34： 28.5°N, 122.272°E; CJ12-1269： 28.861 9°N, 122.515 3°E） from the Min-Zhe coastal mud area were compared to reveal changes of phytoplankton productivity and community structure over the past 100 years. Phytoplankton productivity started to increase gradually from the 1970 s and increased rapidly after the late 1990 s at Site #34; and it started to increase gradually from the middle 1960 s and increased rapidly after the late 1980 s at Site CJ12-1269. Productivity of Core CJ12-1269 was higher than that of Core #34. Phytoplankton community structure variations displayed opposite patterns in the two cores. The decreasing D/B（dinosterol/brassicasterol） ratio of Core #34 since the 1960 s revealed increased diatom contribution to total productivity. In contrast, the increasing D/B ratio of Core CJ12-1269 since the 1950 s indicated increased dinoflagellate contribution to total productivity. Both the productivity increase and the increased dinoflagellate contribution in Core CJ12-1269 since the 1950–1960s were mainly caused by anthropogenic activities, as the location was closer to the Changjiang River Estuary with higher nutrient concentration and decreasing Si/N ratios. However, increased diatom contribution in Core #34 is proposed to be caused by increased coastal upwelling, with higher nutrient concentration and higher Si/N ratios.

A Review of Studies on the Interaction Between Waves and Muddy Bottom

This paper presents a brief review of the results on the interaction between waves and muddy bottom obtained during the last decade including the results obtained by the author at the Coastal Engineering Laboratory of Tianjin University.

淤泥原位固化施工技术研究

海湾滩涂是我国重要的土地资源之一,其特殊的地理环境和地质条件给工程建设带来了极大的挑战。传统的淤泥处理方法存在诸多不足,无法满足现代工程建设的需要。通过对淤泥原位固化施工技术研究,探讨淤泥固化的技术原理,并根据环东海域新城埭头溪(下游段)综合治理工程B标段的应用情况,分析性能指标,确定其可行性,为类似工程提供技术借鉴和参考。

东海闽浙沿岸泥质区沉积特征与古环境记录

2007—2009年执行"我国近海海洋综合调查与评价"专项过程中,对东海闽浙沿岸泥质区进行了系统的底质调查,取得表层沉积物样品2949个、柱状沉积物样品148个。基于上述样品的研究,得到以下认识:(1)以6.5Φ粒径为界线详细划分出泥质区的分布范围,主要位于26°～29°N之间,水深90m以浅的区域。(2)粒径趋势分析结果表明泥质区现代沉积物总体趋势是由东北向西南运移,但研究区的两侧又稍有不同,均表现出明显的向外偏转趋势;南部闽江河口外沉积物运移模式大致表现为由河口向周围呈散射状的输运趋势,最北影响可到27°N附近。(3)泥质区黏土矿物可明显划分为2个组合区,Ⅰ区覆盖了从长江口到南部闽江口外的大片海域,富集伊利石(平均含量为64%),沉积物主要来自于长江;Ⅱ区主要集中在闽江口附近的小区域,富集高岭石和绿泥石(两者平均含量之和为50%),推断其沉积物可能主要来自于闽江。(4)常量元素的R型因子分析表明闽浙沿岸泥质区沉积主要以陆源碎屑沉积为主,伴有少量生物沉积。(5)利用210Pb法测试了研究区百年来沉积速率,结果表明闽浙沿岸泥质区近百年来沉积速率介于0.79～3.34cm/a之间,平均值为1.97cm/a,属于东海次高沉积强度区,明显低于长江口泥质区沉积速率。(6)对闽浙沿岸泥质区南部的MZ01孔进行了综合分析,恢复了中全新世以来泥质区的古环境演变过程,识别出10次极值事件,可能主要由东亚冬季风的增强所引起,推测中全新世以来泥质区东亚冬季风演化过程大致可以分为4个阶段:8400～6300aBP为季风较强且波动期、6300～3800aBP为季风较弱且稳定期、3800～1400aBP为季风高波动期、1400aBP以来为季风稳定增强期。

近8ka东亚冬季风变化的东海内陆架泥质沉积记录

尝试从陆架上寻找全新世高分辨率的东亚季风替代性指标和记录.通过对位于东海内陆架闽浙沿岸泥中部的PC-6孔进行AMS14C年龄测试和粒度分析,综合沉积构造、沉积层序与海平面变化讨论该孔的沉积环境,其下、中、上段分别对应于前滨、近滨和与现今环境基本一致的浅海沉积环境.因上段的沉积作用主要受控于东海冬季沿岸流,通过粒级-标准偏差分析,提取了相对应的粒度组分或粒度子体,该组分的平均粒径被用来作为研究东亚冬季风演化的替代性指标.分析表明,由此方法建立的PC-6孔上段粒径时间序列,较完整地反映了近8 ka来东亚古季风的演化.东亚冬季风的变化呈现出3个各具特点的阶段:7.6～5.1 kaB P.为中等强度的高频率波动;5.1～1.7 kaB P.以多期、较频繁的强盛活动为特点;1.7～0 kaB P.为稳定而较弱的时期.由PC-6孔指示的东亚冬季风活动的强盛期,均在不同区域和材料的记录中找到了相对应降温的证据,说明气候变化的区域性以至全球性联系.

江苏滨海潮滩湿地对潮位变化的生态响应

通过江苏滨海平原典型淤泥质潮滩湿地断面定位观测和样品测试数据与潮位变化关系研究,探讨海平面上升导致淤泥质潮滩湿地生态演替的可能情景。结果表明,淤泥质潮滩湿地的潜水水位和水质、土壤盐分和养分以及潮滩植物种类和生产量等生态组分与潮位变化之间均存在良好的相关关系。据此关系推断,海平面上升,不仅将直接通过增加潮滩湿地的潮浸频率,而且还通过抬高潜水的水位与矿化度,引起潮滩湿地表土积盐和植被退化,进而导致潮滩湿地生态发生逆向演替:生物多样性减少、生产量下降和生态类型趋于单一。上部的茅草滩,已淋洗脱盐的表土因重新返盐(次生盐渍化作用),茅草生长受到抑制,将逐步被较低一级的盐蒿取代,同时由于海堤的阻碍,损失的草滩得不到相应的补偿,最终将可能消失;下部的大米草沼泽,其外缘将不断为光滩所取代,内缘上侵由于受到其繁殖速度的限制,在海平面上升速率较大时补偿速度可能赶不上其退化速度,而导致其分布逐渐变窄,甚至消失;中部的盐蒿滩则由于得到上部草滩退化的补偿和下部大米草沼泽退化的缓冲,范围不断扩大,生态类型多样的潮滩湿地最终将由单一的盐蒿控制。

江苏淤泥质潮滩对海平面变化的形态响应

通过对江苏滨海平原淤泥质潮滩１９８０年以来１９个固定潮滩断面１１２个测次滩面高程测量的统计分析，探讨典型淤泥质潮滩剖面形态对海平面变化的形态响应过程。结果表明，典型淤涨岸段海平面上升，多年平均潮位线以上滩面仍将淤积加高，但淤高幅度除多年平均高潮线附近滩面相对较大外，其余均较小，表明随海平面上升该滩带总体淤积速率将趋于减小；与此相反，多年平均潮位线以下滩面则趋于蚀低，且侵蚀强度较大，表明该滩带的侵蚀有加剧趋向，最终滩面总体形态将因上带不断淤高和下带不断蚀低而逐渐变陡，剖面上凸形态的曲率不断加大。典型侵蚀岸段，海平面上升的效应则相反，海平面上升，多年平均潮位线以上滩面强烈蚀低；而多年平均潮位线以下滩面则强烈淤积加高，剖面的上凹形态最终将因上带不断蚀低和下带不断淤高而趋于平直。

浙江近岸泥质区百年来浮游植物生产力的变化及对环境的响应

在210Pb定年的基础上,对取自浙江沿岸泥质缺氧区的柱样沉积物开展了菜子甾醇、甲藻甾醇、长链烯酮等生物标志化合物分析,根据生物标志化合物含量及比例的分布特征,重建了泥质区110年来浮游植物生产力及群落结构变化。结果表明浙江近岸浮游植物生产力百年来呈上升趋势,自20世纪60年代开始上升,80年代以来有显著增加,浮游植物群落结构则均有甲藻比例上升、硅藻比例下降的趋势。研究认为,浙江沿岸泥质区百年来浮游植物生产力的提高与我国化肥施用量和长江氮的入海通量呈正相关,营养盐N∶P和N∶Si比值的增加导致浮游植物优势种由硅藻向甲藻的转变,说明自20世纪60年代,尤其是自20世纪80年代以来工农业快速发展、大型水利工程建设等人类活动是导致浙江沿岸泥质区海域浮游植物生产力提高及群落结构变化的主要因素。

台风作用下淤泥质海岸动力地貌响应

基于200509号麦莎台风(近似百年一遇)作用前后杭州湾北岸龙泉-南竹港实测的海岸地形和水文资料,利用分形技术、冲刷深度和闭合水深等相关概念分析淤泥质海岸的剖面变化、岸线进退以及地形冲淤,进而探讨海岸响应台风作用的动力地貌行为。结果表明:1)台风作用前后的海岸动力地貌过程表现为水下类似沙坝的堆积体削平、凹处填洼,水下平台发育锯齿或较小的坝——槽,海岸剖面的分维数降低,剖面坡度处于平缓;2)麦莎台风对海床的整体冲淤幅度不大,这可能是由于研究区大潮讯的增水致使波浪对海床的塑造能力减弱以及码头的遮蔽作用造成;3)台风作用对海岸的冲刷深度约为0.8 m,闭合水深为9.5 m,近岸-1 m邻近区成为海岸响应台风作用最敏感的地带;泥沙主要在0 m到闭合水深区间的海床发生纵、横向运移。

海涂围垦区土壤盐分空间变异模拟的比较研究

以苏北海涂围垦区为例,利用人工神经网络(ANN)、普通克里格(OK)插值和序贯高斯模拟(SGS)对典型地块土壤盐分空间分布进行了模拟、插值与预测,获取了各方法的优化结构与参数,并就各方法对土壤盐分分布特征与空间结构的预测能力进行了比较分析。结果表明:ANN、OK和SGS法均较好地模拟和预测了土壤盐分的空间分布,达到了较高模拟、插值与预测精度;ANN获得的土壤盐分空间分布最为连续,SGS法整体分布相对离散;ANN能较好地预测盐分较低的样点,但ANN对高盐分样点的预测结果不如SGS和OK;SGS预测结果最符合实测值的波动特点,ANN预测结果波动范围最窄,SGS较ANN和OK更能反应数据随机变量的结构性和波动性,在整体上要优于ANN和OK法。该结果为滨海地区盐渍土壤的精准评估与高效改良提供了参考依据。

上海滨海滩涂盐生植物分布及其生物量调查研究

以上海及周边地区的滨海滩涂盐生植物为研究对象,采用小样方法调查了盐生植物群落分布,采取烘干法和电导率仪法分别测定其生物量和土壤含盐量,同时运用多元逐步回归分析法研究影响盐生植物群落生物量的因素。结果表明:盐生植物群落分布与滨海滩涂和盐渍土分布规律是一致的,自海向陆具有明显的梯度分布。在沿海防潮堤内侧分布的盐生植物群落主要是小面积的碱蓬(Suaeda heteroptera)群落、芦苇(Phragmites australis)群落和獐毛(Aeluropus sinensis)群落以及上述物种的混合群落。各个地区盐生植物群落生物量变动很大,根据相关关系分析结果,可以认为土壤含盐量是影响滩涂盐生植物群落生物量的重要因素。

近2ka以来东海内陆架泥质区记录的高分辨率古气候演化

通过对位于东海内陆架泥质区中部的MZ02柱样岩芯进行粒度、常量元素、AMS14C分析,获得了粒度和常量元素随时间变化的高分辨率曲线。结果表明,近2 ka以来研究区沉积环境稳定,以沿岸流控制的浅海沉积为主,沉积物中CaO/K2O,MgO/Al2O3和MnO/Na2O比值的变化与我国东部气候变化序列具有较好的一致性,证明这些元素地球化学指标可以作为古气候变化的高分辨率替代性指标。近2 ka以来CaO/K2O、MgO/Al2O3和MnO/Na2O共同识别出的7次极值揭示了同期的降温事件,分别发生在～1 480 a BP(C1),～1 200 a BP(C2),～1 020 a BP(C3),～780 a BP(C4),～580 a BP(C5),～330 a BP(C6),～120 a BP(C7),且在其他区域不同介质中也能找到相应的降温证据,揭示了气候变化的区域性以至全球性联系。

东海内陆架泥质区夏季悬浮体的分布特征及影响因素分析

通过对2007年夏季东海内陆架泥质区悬浮体的测定,探讨了该区悬浮体的分布特征及其影响因素,结果表明悬浮体的平面分布特征为近岸远高于远岸,闽江、瓯江等河流的河口位置浓度最大,等值线基本上平行于海岸线;垂向上悬浮体质量浓度随着水深的加大而增加,高值区大多出现在海底地势凸起的位置。研究区悬浮体的分布主要受陆源入海沉积物和东海流系格局的影响,其中近岸区域主要受控于河流入海物质和闽浙沿岸流;而台湾暖流、闽浙沿岸上升流则对远岸区域影响较大。研究区悬浮体质量浓度和海水浊度的相关性分析显示两者相关系数达0.91,这为通过水体浊度来反演区域的悬浮体质量浓度提供了基础。

人类围垦活动对上海崇明东滩滩涂发育的影响

由于长江口泥沙的淤积,使上海崇明东滩成为一个不断淤涨的土地资源。近50年来,崇明岛共进行了多次大规模的围垦。此项研究以近20年来的LandsatTM和ETM遥感卫星数据为主要数据源,并结合实地景观调查,对不同时期的人类围垦面积和滩涂发育面积之间的关系进行探讨。结果显示,滩涂湿地的面积在逐年变小:从1987年的19705.09hm2锐减到2002年的4773.08hm2,减少了75.78%;并且滩涂湿地面积的年减少率为995.47hm2/a,比年围垦率的729.08hm2/a增加了36.54%。过度围垦后,滩面宽度变窄,自然植被破坏,影响自然促淤,淤涨速率明显减慢。随着滩涂围垦的加剧、未来海平面的上升和河流泥沙大量减少,将会导致潮滩植被进一步破坏。随着崇明东滩每年向外延伸,滩涂湿地也将会发生演替。因此,充分运用“3S技术”,探讨湿地发育和形成的机理,指导科学围垦和土地利用规划,是非常迫切也非常实用的方法。同时,还可以通过动态保护管理,进一步对围垦在经济、生态和环境上的得失作出正确的评价。

盐生植物和秸秆覆盖对滩涂极重度盐土养分和降盐效果的影响

【目的】研究盐生植物和秸秆覆盖对滩涂极重度盐土土壤养分和降盐效果的影响,为沿海滩涂土壤降盐改土提供科学依据。【方法】于2014年5月在江苏沿海滩涂极重度盐土(盐分10 g/kg以上)中开展秸秆和植被覆盖的田间试验,设置对照(CK,裸地)、种植碱蓬(PS)、15 t/ha秸秆覆盖(SM-A)和30 t/ha秸秆覆盖(SM-2A)4种处理,测定各处理0~100 cm(即0~10、10~20、20~40、40~60、60~80和80~100 cm)土壤各层的盐分含量、pH、水分含量和表层养分含量。【结果】与CK相比,1年后SM-A和SM-2A处理的滩涂极重度盐土0~100 cm土壤盐分含量均显著降低(P<0.05,下同),且其0~60、60~80和80~100 cm土壤盐分分别降低96.0%、84.9%和55.8%以上;PS处理可显著降低滩涂表层土壤盐分含量,降低土壤盐分51.0%以上,但对20~80 cm土壤盐分无明显影响。与CK和PS处理相比,1年后SM-A和SM-2A处理的0~100 cm土壤pH和0~60 cm土壤水分含量显著提高;与CK相比,桔秆覆盖处理的表层土壤有机碳含量显著降低,但对土壤全氮、碳氮比和容重等无显著影响(P>0.05)。【结论】综合考虑降盐和培肥效果,秸秆覆盖处理结合适量有机肥施用可能是将来进行滩涂极重度盐土降盐和培肥改土的重要措施。

渤海湾淤泥质海岸潮汐汊道的发育过程

本文以黄河三角洲沿岸为例，论述淤泥质海岸上潮汐汊道的发育过程。研究表明，淤泥质海岸潮汐汊道与废弃河口演化有密切关系。它的外侧海岸是在高海面时形成并被现代动力过程所切割的贝壳砂堤或砂堤。废弃河口演化成潮沟系统的主干。海平面上升以及三角洲地面沉降是诱发汊道纳潮盆地形成的重根因素。海岸迅速后退引起的潮沟溯源侵蚀过程扩大了纳潮面积。一旦贝壳砂岛或砂岛被侵蚀得低于海面，则潮汐汊道开始消亡。刁口和神仙沟、大口河和套儿河以及曹妃甸的当前状态可以代表淤泥质海岸潮汐汉道的形成、成熟以及消亡过程的三个阶段。