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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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Relationship between biogeochemical features of biogenic elements and flocculation in the Changjiang Estuary 总被引：1，自引：3，他引：1
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INTRODUCTIONItiswellknownthattheregenerallyexistsahigherconcentrationsedimentzoneinrivermouththanthatinthe'upperandlowerones,whichiscalledturbiditymaximum(TM).ButnomoreintensiveresearchonthisphenomenonhadbeenconductedforalongtimesinceitwasfoundinFrenchGirondeEstuaryin1938.Itwasnotuntilthe1950swhenitattractedresearchersallovertheworldandwasregardedasacommonphenomenoninanestuary.Itplayedanimportantroleinestuarinesedimentationandenvironment.Sincethe1960s,lotsofstudiesonTMintheChangjiangE… 相似文献
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长江口潮滩表层沉积物对NH4+-N的吸附特征 总被引：9，自引：0，他引：9
沉积物对NH4+-N的吸附是氮素生物地球化学循环的关键过程之一,它在河口潮滩生态系统内氮素循环过程中起着非常重要的作用.以长江口滨岸潮滩为研究区域,运用实验模拟的方法,研究了沉积物对NH4+-N的吸附特征,结果表明,在长江口潮滩上覆水和孔隙水中NH4+-N含量的变化范围内,沉积物对NH4+-N的吸附呈线性变化;研究区域内沉积物对NH4+-N的吸附系数为3.81~9.00,且与沉积物中有机碳(TOC)含量有良好的相关关系,它揭示了有机质控制着长江口潮滩沉积物中NH4+-N的吸附行为.实验模拟与实测结果对比发现,在潮滩自然环境条件下,研究区域内沉积物对NH4+-N的吸附处在非热力学平衡状态过程中.盐度是影响NH4+-N吸附过程的重要环境因子,且导数方程关系式在低盐度范围内,盐度的微小变化对NH4+-N的吸附有显著的影响. 相似文献
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Distribution of organic carbon in sediments and its influences on adjacent sea area in the turbidity maximum of Changjiang Estuary in China 总被引：2，自引：0，他引：2
Distributions and sources of total organic carbon （TOC）in seabed sediments and their implications for hydrodynamics are analyzed, in the turbidity maximum of the Changjiang Estuary. Ecology ecoenvironmental effects of estuary water on the continuously increasing terrigenous organic carbon from the Changjiang River are also explored through variations of organic carbon content and water quality indicators. Results show that, hydrodynamics exert important influences on distributions of organic carbon in the tur- bidity maximum of Changjiang Estuary. For their redistribution effect of terrigenous organic carbon within the moving layer in the whole region, variations from land to sea are not indicated by surficial and vertical average values of TOC and total nitrogen （TN） contents in core sediment, as well as organic stable carbon isotopes in surface sediments. However, on the long-time scale, the trend of terrigenous organic carbon decreasing from land to sea is still displayed by variations of stable carbon isotopic average values becoming heavier from land to sea. Previous studies have shown that high content of Chl a cannot appear in the Changjiang Estuary in despite of adequate nourishment supply, because photosynthesis of phytoplankton is constrained by high suspended sediment concentration（SSC）. However, an area with a high content of Chl a occurs, which may be caused by resuspended benthic algae with bottom fine grain-size sediments. Tremendous pressures are imposed on the environment of Changjiang Estuary, because of uhrophication trends and special hydrodynamics. Phytoplankton bloom area tends to extend from the outer sea to the mouth of Changjiang River. 相似文献
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珠江口最大浑浊带的形成与季节变化 总被引：3，自引：0，他引：3
应用Delft3D研究了珠江口最大浑浊带的分布以及影响因素。盐度和悬沙浓度的垂向分布揭示出最大浑浊带范围的变化。最大浑浊带在干季的悬沙浓度比湿季更大,而其中心位置与湿季相比向上游移动10 km。最大浑浊带的形成受到潮汐、径流和地形的综合影响,而沉积物的再悬浮和垂向环流为影响最大浑浊带的主要因素。 相似文献
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长江河口及邻近海域表层沉积物中铁溶解和磷释放活性的动力学表征 总被引：1，自引：0，他引：1
运用溶解动力学实验及活性连续体模型表征了长江河口至东海邻近海域表层沉积物中铁(Fe)和磷(P)的活性。通过动力学数据拟合得到了活性组分的理论含量m0和表观速率常数k。结果表明，Fe(Ⅱ)普遍存在于表层沉积物中，这应是高活性有机络合态Fe(Ⅲ)絮凝/沉淀到沉积物中后快速还原的结果。沉积物中黏土及总有机碳（TOC）含量对Fe(Ⅱ)的m0及其k值起重要控制作用。从长江河口至邻近海域沉积物中Fe(Ⅱ)均以FeCO3形态为主，FeCO3的溶解及与之相结合磷(主要为交换态P和自生P)的释放导致Fe(Ⅱ)和P具有相似的溶解动力学特征。与吸附于Fe(Ⅱ)矿物相的P相比，与Fe(Ⅱ)矿物相共沉淀的P的m0较高，但k较低。与TOC含量较低的粗粒沉积物中的Fe(Ⅲ)相比，TOC含量较高的细粒沉积物中Fe(Ⅲ)的m0值较小，但k值较大。以上特征是Fe不同的氧化还原过程导致的。Fe(Ⅲ)氧化物的含量(m0)和活性(k)总体上控制着与之相结合P的含量(m0)及溶解活性(k)。虽然传统活性Fe形态分析未能揭示出长江河口沉积物中活性Fe的富集作用，但溶解动力学表征结果表明，Fe的絮凝/沉淀导致河口沉积物中活性Fe的明显富集，且该过程主要发生在盐度明显增加的低盐度河口区。 相似文献
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根据2003和2006年长江口及邻近海域表层沉积物样品的粒度组成和元素铬、铜、镍、铅、锌、铝、钙和锶的含量,分析了重金属元素含量的分布特征,探讨了含量的变化趋势及其对人类活动的响应。自2003年三峡工程一期蓄水完成到2006年6月,长江输沙量逐年减少,长江口海域沉积物中黏土的百分含量明显增加,但是沉积物分布的总体格局并没有发生明显的变化。重金属元素大多在泥质区沉积物中富集,高值区沿岸线呈带状分布,在最大浑浊带和口外羽状锋处达到峰值。在长江大量物质输入的背景下,研究区沉积物中重金属元素含量相对其他类似河口较低。河流的陆源颗粒输入、水动力条件、细颗粒物质的吸附以及絮凝作用是控制沉积物中重金属元素含量分布的主要因素,氧化还原条件也对重金属元素含量变化有一定的影响。人类活动(重大工程的建设和人为污染)对长江口外泥质区中重金属元素含量有重要影响,尤其对铅和锌的含量及其分布的影响显著。自2003年三峡工程一期蓄水以来,长江口海域表层沉积物中重金属元素沉积机制未有明显的变化,但是重金属元素含量有逐渐降低的趋势。 相似文献
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长江口北槽浮泥周期性变化初探 总被引：1，自引：3，他引：1
根据2000年长江口北槽浮泥的实测资料,分析浮泥厚度和体积等几何尺度随时间的变化,发现长江口北槽浮泥存在日、半月和年际三种周期变化;日周期的变化受潮流动力周期的控制,这是由潮流冲刷浮泥形成的悬沙并再絮凝沉积造成的;半月周期的变化受潮流半月周期变化引起的泥沙供给量的变化控制;年周期的变化主要是由影响细颗粒泥沙絮凝沉积的长江口水温的年度变化所控制,泥沙供给和动力的年周期变化也有一定的影响. 相似文献
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长江口及邻近海域细颗粒沉积物中重金属的空间分布及沉积通量 总被引：4，自引：0，他引：4
长江每年输送大量的泥沙进入东海,其中细颗粒沉积物具有搬运距离远、扩散范围大的特点,成为示踪河口及近海沉积物源汇过程的良好载体。本文基于采自长江口及邻近海域的44个表层沉积物样品,分析了细颗粒组分中重金属的空间分布和沉积通量,探讨了重金属来源和搬运沉积过程。研究表明:长江口及邻近海域细颗粒沉积物中Cu、Cr、Ni、V和Zn含量、沉积通量的空间分布具有高度的相似性,总体表现为长江口及浙闽沿岸高,向外急剧降低;该区细颗粒沉积物中的重金属主要来自长江,入海后向两个方向扩散,其一为向西南方向扩散,沉积于内陆架泥质区;其二是向东的跨陆架输送,沉积于长江冲淡水影响的海域。从长江口向西南方向的输送和沉积是长江入海重金属最重要的汇。 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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Li Yan Wang Yaqin LinYian
Associate Professor Second Institute of Oceanography State Oceanic Administration Hangzhou Senior Engineer Second Institute of Oceanography State Oceanic Administration Hangzhou 《中国海洋工程》1995,(3)
- Settling characteristics of floes, including relative settling velocity, relative flocculation coefficient and flocculation exponent, are obtained by the suspended load equations for different size fractions. Data of the Changjiang Estuary suggest that level of flocculation changes from river section, river mouth (turbidity maximum) to offshore area in sequence of low, very high and high. The settling characteristics of floes reflected by in situ estimation performs a similar feature as that obtained from still water experiment. 相似文献
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The concentrations of dissolved aluminum (Al) in the upper St. Lawrence Estuary were determined during periods of high and intermediate river-discharge. Laboratory experiments simulating estuarine processes were also conducted in order to examine possible mechanisms controlling the Al distribution. During the high river-discharge, the Al concentration at river end-member was 1.63 µM and decreased exponentially with increasing salinity. An almost complete removal of dissolved Al was observed in the low salinity area up to 10 with an intensive removal in the turbidity maximum zone. Principal mechanisms responsible for the Al removal inferred from the laboratory experiments were flocculation and adsorption onto suspended particulate matter (SPM). During the intermediate river-discharge, the Al concentration was 0.72 µM at the river end-member and again decreased with increasing salinity. However, the removal was less pronounced, being only about 25%. Good fits with model predictions and laboratory experiments suggest that principal removal mechanisms were authigenic aluminosilicate formation and adsorption onto SPM. In the upper St. Lawrence Estuary, Al distribution is controlled by a combination of three removal mechanisms: flocculation, authigenic aluminosilicate formation, and adsorption. Each mechanism can become a dominant factor depending on the concentration level and speciation of dissolved Al in the river water. 相似文献
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基于水淘选分级的长江口最大浑浊带附近颗粒有机碳的来源、分布和保存 总被引：6，自引：6，他引：0
从分粒级的角度研究大河河口颗粒有机碳的输送特征是深刻理解河口淡咸水混合过程中有机碳的生物地球化学过程的关键。于2011年6月采集了长江口最大浑浊带附近盐度梯度下的表层悬浮颗粒物,采用水淘选方法对其按照水动力直径大小进行了分级分离,分析了这些颗粒物的有机碳含量、稳定碳同位素组成及颗粒物比表面积等参数,讨论了不同粒级颗粒物上有机碳的来源、分布和保存随盐度的变化特点及其影响因素。结果表明,随着盐度的增加和粒径的增大,长江口最大浑浊带附近分级颗粒有机碳逐渐降低,颗粒有机碳含量主要集中在小于32μm的粒级。相对于长江干流,长江口颗粒有机碳含量偏低,可能归因于河口最大浑浊带附近特殊的生物地球化学作用,如细颗粒物絮凝——沉降、微生物分解等。基于蒙特卡洛模拟的三端元混合模型的计算表明长江口分级颗粒有机碳主要来源于河流和三角洲输入,海洋来源贡献较小,三者的平均贡献比例分别为40%、35%和25%。在河口盐度梯度的淡水端,不同粒级颗粒物上三角洲来源的有机碳比例均随着盐度升高而增加,而在咸水端,海源有机碳的贡献比例升高,尤其是在16-32μm粒级,最高达39%。32-63μm粒级的颗粒物单位比表面积有机碳含量均大于1.0mg/m~2,小于32μm的颗粒物单位比表面积有机碳含量均在0.4-1.0mg/m~2的范围之内,符合河流颗粒物的一般特点,同时也说明细颗粒物上的有机碳可能已经发生了一定程度的分解,不过相对于长江口表层沉积物,颗粒物单位比表面积有机碳含量普遍较高,表明这些颗粒有机碳在沉降过程中或沉积之后还要经历进一步的再矿化分解,初步的估算表明,长江所输送的陆源有机碳约71%会在沉积过程中损失掉。本研究有助于深入了解大河河口不同粒级颗粒物在有机碳迁移转化过程中的作用,深化对高浊度河口有机碳生物地球化学过程的认识。 相似文献
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长江口最大浑浊带是陆海交汇的核心区域,其航槽是扼海-河联运的咽喉,悬沙峰的涨落潮周期变化深刻影响航槽的稳定性。本文利用长江口南槽上、中、下段3个站点枯季小潮和大潮的流速、盐度、悬沙平均粒径和悬沙浓度的实测资料,分析最大浑浊带悬沙峰特征及其动力机制。发现:流速和滩槽交换增强导致大潮平均悬沙浓度比小潮增加了0.78—1.97倍,絮凝也导致憩流底层悬沙浓度增加8%左右,但流速和絮凝与悬沙浓度的关系均非线性。大小潮盐度梯度与底层悬沙浓度关系呈现高线性相关关系,表明盐度梯度强化或突变是泥沙再悬浮形成悬沙峰的主要动力。 相似文献
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A. E. J. Miller 《Estuarine, Coastal and Shelf Science》1999,49(6):891
A high temperature catalytic oxidation (HTCO) technique was used to measure dissolved organic carbon (DOC) during seasonal surveys of the Tamar Estuary, U.K. At the time of the programme, the field of DOC analysis had been plagued by numerous analytical difficulties. However, using thorough calibration of the analytical systems and the systematic analysis of an internal reference material, a valuable estuarine DOC data set was produced. The range of DOC concentrations observed (478–110 μM C) is consistent with the published data for riverine and coastal sea waters respectively. The Tamar Estuary is a freshwater DOC-dominated system, with strong correlation between lateral DOC distribution and salinity. However, mixing behaviour was not strictly conservative. During tidal cycle studies at a fixed station, DOC concentrations appeared to be uncoupled from salinity, and were inversely related to turbidity. It is concluded that tidally-induced resuspension of bottom sediments provided the dominant control mechanism for DOC concentration. The Tamar Estuary shows contrasting behaviour to the larger, more heavily impacted, Severn Estuary. Hence it is likely that the behaviour of DOC in estuaries cannot be classified as typical per se, but is a function of the natural and anthropogenic characteristics of the catchment and hydrology. 相似文献