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伶仃洋河口泥沙絮凝特征及影响因素研究 总被引：1，自引：1，他引：0
泥沙絮凝对河口细颗粒泥沙运动过程起着极其重要的作用。本文通过LISST-100激光粒度仪等仪器实测伶仃洋河口2013年洪季悬浮泥沙絮凝体现场粒径及水动力、泥沙条件,结合实验室悬沙粒径分析,研究大小潮期间伶仃洋河口泥沙絮凝特征,探讨紊动剪切强度、含沙量、盐度分层及波浪等因素对伶仃洋河口泥沙絮凝的影响。结果表明:伶仃洋河口水体中现场粒径平均值为148.53 μm,大于实验室悬沙分散粒径36.74 μm,河口絮凝现象明显;沉速与有效密度、粒径呈正相关,絮团平均有效密度为153.49 kg/m3,平均沉速达1.13 mm/s;小潮时絮团平均粒径大于大潮,垂向上表底层絮团粒径小、中层大,中底层絮团沉速大于表层。伶仃洋河口水动力、泥沙条件是影响其泥沙絮凝的重要因素,低剪切强度（小于5 s-1）、低含沙量（小于50 mg/L）及高体积浓度有利于细颗粒泥沙之间的相互碰撞,促进絮凝作用;当剪切强度与颗粒间碰撞强度高于絮团所能承受的强度时,絮团易破碎分解成小絮团或更细的泥沙颗粒;伶仃洋河口盐度层化引起的泥沙捕获现象增大中层泥沙体积浓度,有利于中层絮凝体的发育;观测期相对较大的波浪增强水体紊动,增大了水体细颗粒泥沙的碰撞几率,表层絮团粒径随波高峰值的出现而增大。 相似文献
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长江口细颗粒泥沙絮凝作用及其制约因素研究 总被引：14，自引：1，他引：13
简要介绍了人海河口细颗粒泥沙的絮凝机理;以长江口细颗粒泥沙絮凝作用的研究为例,概述了影响河口细颗粒泥沙絮凝的若干因子;着重介绍了长江口水体生物地球化学过程对于细颗粒泥沙絮凝作用影响的研究进展。在此基础上,结合国内外相关研究的最新进展以及河口工程与环境中的泥沙问题,提出未来工作设想。 相似文献
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钱塘江河口细颗粒泥沙絮凝沉降特性研究 总被引：3，自引：0，他引：3
钱塘江口河口上游河流和海域来沙多为细颗粒泥沙,粘性细颗粒泥沙由于其特殊的表面电化学性质遇到强电解质海水而产生絮凝沉降,是形成河口淤积的原因之一。影响絮凝的因素很多,除了电解质,还有泥沙粒径的大小、盐度、含沙量、PH值、温度、有机质含量、矿物成分、水流速度及紊动情况等。本文通过粒度分析、静水沉降、动水沉降等各种实验手段分析钱塘江口泥沙的基本特性,找出最佳絮凝盐度以及泥沙不淤流速等值,初步探讨了细颗粒泥沙的絮凝机理,为治理钱塘江口提供科学依据。 相似文献
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河口细颗粒泥沙的絮凝作用 总被引：13，自引：0，他引：13
本文对河口细颗粒沙絮凝作用的研究工作进行了综合评述。以盐度，有机物，水流切应力及悬浮颗粒的表面电荷等因素对河口细颗粒泥沙絮凝作用的影响规律及絮凝机理进行了总结和探讨。 相似文献
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本文对河口细颗粒泥沙絮凝作用的研究工作进行了综合评述．对盐度、有机物、水流切应力及悬浮颗粒的表面电荷等因素对河口细颗粒泥沙絮凝作用的影响规律及絮凝机理进行了总结和探讨． 相似文献
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长江河口有机质含量丰富,盐度变化较大,因此研究长江河口以细颗粒泥沙为主的多因子共同作用下的絮凝有助于了解最大浑浊带的形成机制.通过实验研究盐度和腐殖酸共同作用对长江口细颗粒泥沙浊度变化影响的过程,从浊度相对变化率、絮团粒径和电位变化三方面综合分析了其絮凝机理,并且对絮凝体进行了红外和电镜分析,探讨了絮凝体的微观结构.结果表明:(1)随着盐度增大细颗粒泥沙浊度相对变化率逐渐增大,粒径增大,而电位绝对值变小;(2)随着腐殖酸浓度增大细颗粒泥沙浊度相对变化率先略有升高后迅速降低,粒径增大,电位绝对值增大;(3)微观结构的分析表明腐殖酸是以腐殖酸盐的形式包覆在泥沙表面,同时也验证了河口中C-P-OM(C代表黏土,P代表阳离子,OM代表有机化合物)的泥沙絮凝模式. 相似文献
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长江口泥沙絮凝静水沉降动力学模式的试验研究 总被引：10，自引：1，他引：10
细颗粒泥沙在咸水中的絮凝沉降是河流泥沙向海输送过程中在河口区发生的重要现象，是河口拦门沙形成与发育的主要原因之一。本文根据室内模拟试验研究，提出长江口泥沙絮凝静水沉降的二级动力学模式，通过该式求得不同泥沙含量和盐度情况下絮凝沉降的衰减系数，半衰期和平均沉降速率等动力学参数，定量地分析泥沙含量和盐度对泥沙絮凝沉降过程的影响。 相似文献
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珠江口磨刀门泥沙絮凝特征 总被引：3，自引：3，他引：0
本文利用激光粒度仪实测得到珠江口磨刀门河口2013年夏季悬浮泥沙现场絮凝及絮凝体特征,同时对比悬沙分散粒径和含沙量,研究表明:悬沙分散粒径平均值为27.9μm,现场实测絮团粒径平均值为91.6μm,表明磨刀门口外的悬浮泥沙絮凝现象显著;实测絮团平均粒径变化范围为13.0~273.8μm,小潮期间絮团粒径平均值为131.5μm,大于大潮平均值76.9μm;絮凝体粒径在垂向上的变化表现为由表及底先变大再变小。絮团体积浓度、沉速与粒径的关系在不同情况下有差异,体积浓度和絮团粒径在表层和中层有明显正相关关系,絮团沉速在大潮时刻随着粒径的增大而增大。综合分析影响絮凝的因素,得知在珠江口盐度对于絮团大小影响不明显;而流速大小的差异是影响大小潮之间絮团大小不同的主要因素。研究结果有助于了解珠江口细颗粒泥沙输移特性和相关生物化学过程。 相似文献
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本文基于现场观测的絮团粒径、悬沙浓度及水动力数据,研究了黄河口南部潮滩泥沙絮凝特征。研究发现,黄河口潮滩絮团粒径在25.42～264.44 μm之间,平均为95.20 μm。水体紊动对黄河口潮滩絮凝的影响存在差异,紊动对絮凝促进作用的上限约为Gl=3.76 s?1。紊动强度低于Gl时,紊动促进泥沙絮凝,絮团粒径随紊动加强而增大;反之水体紊动对絮凝主要起抑制作用,絮团粒径随紊动强度增大而减小。悬沙浓度对黄河口潮滩泥沙絮凝起抑制作用,同等紊动条件下高悬沙浓度对应的絮团粒径更小。黄河口潮滩絮团有效密度与粒径呈现负相关关系,沉速主要受粒径影响。本研究补充了对弱潮河口潮滩泥沙絮凝特性的认识。 相似文献
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试验研究了NaCl和CaCl22种电解质加入量对不同粒径玻璃微珠(S1,S2,S3)和蒙脱石(M0)悬浮液Zeta电位的影响,以考察颗粒性质、颗粒粒径和电解质对Zeta电位和悬浮液稳定性(分散或团聚)的影响。试验结果表明,粒径较大的玻璃微珠S1和S2悬浮液Zeta电位随电解质的增加而逐渐增加,与文献中的描述基本一致;但粒径较小的玻璃微珠S3和蒙脱石M0悬浮液的Zeta电位随电解质的增加呈现出一些异常的变化,特别是在零电点附近发生了剧烈波动。分析S3和M0悬浮液Zeta电位出现异常变化的原因,可能是微细颗粒在零电点附近发生了较为明显的分散-团聚-再分散过程,团聚或分散过程又反过来影响到悬浮液的Zeta电位和粒度分布。 相似文献
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随着我国邮轮产业的发展，各港口城市相继以建设邮轮母港来发展邮轮经济，但大多数邮轮港口经济收益甚微，形成邮轮港口供大于求的市场局面，并出现不良竞争和重复建设的问题，亟须合理规划和建设邮轮港口、科学配置相关资源以及促进邮轮旅游产业良性发展。文章利用赫芬达尔 赫希曼指数和偏离 份额分析法，对2008—2018年中国主要邮轮港口群（渤海湾邮轮圈、长三角邮轮圈和南部邮轮圈）进行空间聚集和竞争格局分析，并提出发展建议：加强整体规划，促进区域合作；稳定上海港的邮轮中心地位；细分港口资源和区域特色，对渤海湾邮轮圈差异化定位；充分发挥南部邮轮圈的发展优势。 相似文献
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Abstract. The dispersion pattern of mciobenthic harpacticoid copepods was measured on a mudflat at different tidal conditions. Samples were collected using a 5 times 5 array of contiguous cores (8 mm ID), and analyzed by spatial autocorrelation (MOHAN'S I statistic). Four species were abundant, and all were judged to be patchy by autocorrelation. The apparent scale of patchincss did not differ with tidal stage. Three species were aggregated at very small spatial scales (0.5 to 1cm2 ), with patches probably distributed at random within a sampling array. The fourth species was also aggregated at the smallest spatial scale (neighboring cores), but may have been regularly spaced at distances longer than 5 cm. This study shows that processes on the order of several cm2 must dictate the patch dynamics of small metazoans. 相似文献
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《Deep Sea Research Part I: Oceanographic Research Papers》2006,53(2):310-320
According to combined observations from vertical plankton tows, dredging with epibenthic nets 1 m above the ocean floor, video recordings and acoustic data from a scanning sonar obtained during descent and during deployment on the ocean floor, the calanoid copepod Calanus hyperboreus was aggregated in high concentrations near the ocean floor of the Greenland Sea between 2300 and 2500 m during late July and August. Concentrations were highest very close to the ocean floor and decreased rapidly further upward. These nearly mono-specific aggregations were apparently drifting in cloud-like formations with a horizontal extension of ca. 270 m with the near-bottom currents. Maximum abundances observed were up to 2 orders of magnitude higher than in the water column. The biomass in the bottom 20 m layer was around 18% of the biomass in the rest of the water column. Stage composition, reduced metabolic rates and insensibility to mechanical stimuli indicate that these C. hyperboreus were representing the resting population. The fact that high concentrations were observed during deployments lasting >1 d and in 3 years suggests that aggregation near the ocean floor is a regular, rather than an extraordinary, pattern in the life history of C. hyperboreus in the Greenland Sea, but there is need for comparison with other seas and eventually other Calanus species. 相似文献
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The kinetics of aggregation of riverine colloidal iron have been examined using a stopped-flow technique which probes the first few seconds of mixing between river and sea water end members. A significant fraction, up to 80%, of the colloidal iron is aggregated during the first 1–2 s of mixing, indicating that the aggregation process is much faster than previously thought. Most of the aggregation induced by seawater results from the divalent cations Mg2+ and Ca2+, with the overall ionic strength having little influence. At equal concentrations of 27 mM, the rate of aggregation by alkaline earth cations increased with ionic size Mg2+ < Ca2+ < Sr2+ < Ba2+. The aggregation rates were indifferent to the anion (Cl− or SO42−) present. Very high aggregation rates were also induced by the common water treatment coagulant Al2(SO4)3 at concentrations in the range 20–30 µM Al(III), several orders of magnitude lower that those used for the seawater cations. Our results support the view that specific chemical interactions between the cations and the colloid particle surface, rather than simple electrical effects, control the colloid stability. 相似文献
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Lee Donggil Oh Wooseok Gim Byeong-Mo Lee Jung Suk Yoon Euna Lee Kyounghoon 《Ocean Science Journal》2019,54(4):573-579
Ocean Science Journal - Efficient fish aggregation systems are essential for catching chub mackerel (Scomber japonicus), which is a major target of purse seine fisheries in South Korea. To aid the... 相似文献
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In this study, the dB difference and characteristics of krill swarms inhabiting Subarea 48.1, which includes the west and south of the South Shetland Island and the Elephant Island peripheries, were estimated to distinguish Antarctic krill, using acoustics. From April 13 to 24, 2016, acoustic data were collected along 24 survey lines using the frequencies 38 and 120 kHz, and middle trawling was performed at 7 stations. Using the difference between the dB values of two volume backscattering strength (Sv) frequencies (38 and 120 kHz), a clear acoustic distinction could be made between Antarctic krill (4.9 to 12.0 dB) and fish (?4.0 to ?0.2 dB). The distributions and mean Sv of krill swarms in the Elephant Island peripheries and south of South Shetland Island were higher than those in the west of South Shetland Island. The mean length/ height ratio of krill swarms in the west of the South Shetland Island (64.5) was higher than that in the south (35.9) and the Elephant Island peripheries (33.8), with the length of the aggregations exceeding their height. Most krill swarms were distributed between the surface layer (less than 10 m below sea level) and within 200 m of water depth. These results are expected to serve as baseline data for evaluating krill density and biomass by distinguishing them from fish, using acoustics. 相似文献
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Hideo Sekiguchi 《Journal of Oceanography》1983,39(3):119-128
According to studies made to date, the planktonic larvae ofPinnixa rathbuni, especially the early zoeal stages, have been found mainly in the eastern part of Ise Bay (Pacific coast of central Japan), while the benthic adult population is restricted to the southwestern part of the bay. The present study was made to obtain a better understanding of the origin of the dense population of early zoea found along the coast of the Chita Peninsula in the eastern part of the bay. Field surveys made with a Smith-McIntyre grab from May to November 1981 (every two months) ruled out the possibility that the benthic adult crabs in the southwestern part of the bay migrated to the eastern part of the bay to release their larvae, or that a substantial population of the crabs occurred in the eastern part of the bay. Thus, the larvae may be derived wholly from the benthic adult populations localized in the southwestern part of the bay. The spatial distribution of the early larvae can be explained by assuming that the larvae, released by the benthic adult population in the southwestern part of the bay, are rapidly transported toward the Chita Peninsula and form a dense larval population along the coast in the eastern part of the bay. 相似文献