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1.
以苯酚为研究对象，系统地研究了其在南海沉积物上的吸附行为。实验中作者利用紫外可见分光光度计测定苯酚在沉积物上吸附前后的浓度变化，从而可以根据平衡浓度(Ce)和吸附在沉积物上的量(Cs)的关系来推测苯酚在沉积物上的吸附机理。研究表明，苯酚在海洋沉积物上的吸附行为可以同时很好地用Freundlich型、Langmuir型和线型三种吸附等温式来描述，这说明其吸附行为比较复杂。另外，通过改变吸附条件发现苯酚吸附行为受沉积物有机质的含量、介质的盐度、温度、酸度等因素的影响，并且饱和吸附量随着沉积物有机质含量、介质盐度和酸度的升高而增大，随着温度的升高而减小。 相似文献
2.
本文对常用塑料增塑剂邻苯二甲酸二丁酯( DBP)在海洋沉积物上的吸附行为进行研究,发现它的吸附机理主要是在沉积物上的有机质间分配及表面吸附和微孔作用,吸附与有机质含量和黏土矿物的含量有一定的相关性.在实验浓度范围内,DBP在3种不同处理方式沉积物上的吸附行为分别可以用Linear和Freundlich等温式来描述.通过改变吸附条件发现,随着盐度减小、温度的增加,吸附能力减小;而随酸度的升高,吸附能力先升高后下降.此外,通过向体系中加入不同表面活性剂来模拟双溶质体系的方法,对DBP与表面活性剂的竞争吸附行为进行了研究.结果发现,十六烷基三甲基溴化铵(CTAB)和吐温80(Tween80)的加入使DBP的吸附能力增强;十二烷基苯磺酸钠(SDBS)的加入使DBP的吸附能力降低. 相似文献
3.
黄河口磷酸盐缓冲机制的探讨 总被引：13，自引：2，他引：11
以黄河口为研究对象,通过对温度、盐度、平衡时间、县浮物含量等模拟河口现场条件,对黄河口磷酸盐的缓冲机制进行了探讨,黄河口悬浮行对磷酸盐的吸附和解吸一般在４－５ｈ后就已趋于平衡;随着水体悬浮物含量的增加,对磷酸盐的吸附－解吸量呈指数形式下降,粒度减小使吸附量－解吸量呈指数形式增加,盐度对解吸量的影响程度大于吸附量,最大附和最小解吸出现在低盐度区;温度对吸附－解吸平衡的影响较大,随温度升高吸附量和解吸 相似文献
4.
黄河口海域盐度变化受黄河入海径流量、气候及海洋动力条件的影响,河口沉积物的沉降、固结及侵蚀等动力学行为与黄河口海域盐度变化有密切关系。为研究不同盐度环境对河口沉积物抗侵蚀性变化的影响,在现代黄河三角洲刁口河路潮滩上进行原位试验,模拟不同盐度的沉积环境,使用黏结力仪（CSM）对细粒沉积物进行抗侵蚀性测试。结果表明细粒沉积物的临界剪应力为0.728～1.581Pa,且随着沉积环境盐度增加,细粒沉积物的临界剪应力呈线性增加。当沉积环境盐度增加1时,其临界剪应力增加约0.02Pa。 相似文献
5.
《海洋地质与第四纪地质》2016,(5)
黄河口海域盐度变化受黄河入海径流量、气候及海洋动力条件的影响,河口沉积物的沉降、固结及侵蚀等动力学行为与黄河口海域盐度变化有密切关系。为研究不同盐度环境对河口沉积物抗侵蚀性变化的影响,在现代黄河三角洲刁口河路潮滩上进行原位试验,模拟不同盐度的沉积环境,使用黏结力仪(CSM)对细粒沉积物进行抗侵蚀性测试。结果表明细粒沉积物的临界剪应力为0.728~1.581Pa,且随着沉积环境盐度增加,细粒沉积物的临界剪应力呈线性增加。当沉积环境盐度增加1时,其临界剪应力增加约0.02Pa。 相似文献
6.
黄河口磷酸盐缓冲机制的探讨──Ⅰ.黄河口悬浮物对磷酸盐的吸附-解吸研究 总被引：8，自引：0，他引：8
以黄河口为研究对象,通过对温度、盐度、平衡时间、悬浮物含量等模拟河口现场条件,对黄河口磷酸盐的缓冲机制进行了探讨。黄河口悬浮物对磷酸盐的吸附和解吸一般在4－5h后就已趋于平衡;随着水体悬浮物含量的增加,对磷酸盐的吸附-解吸量呈指数形式下降,粒度减小使吸附量-解吸量呈指数形式增加;盐度对解吸量的影响程度大于吸附量,最大吸附和最小解吸出现在低盐度区;温度对吸附-解吸平衡的影响较大,随温度升高吸附量和解吸量均呈线性关系增加,且平衡时间有所延长。 相似文献
7.
8.
本文对采自渤海、黄海和东海3个典型海域的沉积物进行了尿素吸附/解吸的实验室模拟研究，用Freundlich吸附模型和Henry吸附模型分析了不同沉积物对尿素吸附的热力学特性，并研究了温度、沉积物粒径、有机质含量等因素对尿素在沉积物表面吸附的影响。结果表明，沉积物对尿素的吸附/解吸过程总体呈现3个阶段:快速吸附阶段（0~5 h）—慢速吸附阶段（5~12 h）—平衡阶段（12 h之后）。当水体中的尿素浓度较低时，沉积物解吸释放尿素，随着上覆水中尿素浓度逐渐增加，沉积物对上覆水中的尿素产生吸附行为，各海区沉积物对尿素的吸附能力由强至弱依次为渤海、东海、黄海，这可能与沉积物的类型有关。Freundlich方程和Henry方程均可模拟沉积物对尿素的吸附，温度、粒径以及沉积物中有机质含量等因素均对尿素在沉积物上的吸附产生影响，随着温度升高，尿素在沉积物上的吸附量变小，沉积物粒径越小，有机质含量越高，吸附尿素的能力越强，因此，揭示尿素在沉积物表面的环境行为时，必须考虑以上因素的影响。 相似文献
9.
黄河口沉积物对磷酸盐的吸附与释放 总被引：44，自引：2，他引：44
本文对黄河口典型沉积物进行了吸附磷及释放磷的研究,结果表明黄河口地区浅海沉积物对磷的释放极少.阴离子表面活性剂的存在能降低对磷的吸附能力,溶液pH的增大对吸附量有增大的作用,硝酸盐的存在不影响沉积物对磷的吸附.沉积物吸附大量磷后的再释放是缓慢的.经测定,沉积物吸附/解吸平衡点一般为0.24～4.27μmol/dm3,此值一般高于底层水磷浓度,因此我们推测除粗颗粒样品外,黄河口地区浅海沉积物有向上覆水释放磷的倾向. 相似文献
10.
1994年5月—1995年6月,利用黄河口悬浮颗粒物,在实验室内于不同温度、盐度、磷酸盐浓度、pH值及悬浮物粒度条件下进行了悬浮物对磷酸盐的吸附和解吸模拟实验,通过水体中几种磷—钙矿物的离子平衡计算,对黄河口磷酸盐的缓冲机制进行了探讨。结果表明,黄河口现场条件下水体中钙与磷之间存在某些离子平衡,黄河口水体中磷—钙矿物的离子积受温度、悬浮物种类及粒度影响较小,而与水体盐度、磷酸盐及钙含量有关,但不足以形成磷—钙矿物沉淀;磷—钙矿物的沉淀和溶解在黄河口磷酸盐浓度的控制机制上所起的作用较小,而悬浮颗粒物表面对磷酸盐的吸附和解吸起了较大的作用。 相似文献
11.
The characteristics of the nematode faunas in subtidal sediments of a large microtidal estuary and nearshore coastal waters differ markedly 总被引：1，自引：0，他引：1
M. Hourston I.C. PotterR.M. Warwick F.J. Valesini 《Estuarine, Coastal and Shelf Science》2011,94(1):68-76
The present study examines traditional paradigms regarding the differences between faunas in estuaries vs coastal waters. The ecological characteristics of the free-living nematode faunas of nearshore, subtidal sediments in downstream and upstream areas of the large, microtidal Swan River Estuary are compared with those similarly recorded seasonally in subtidal sediments along an adjacent part of the coast of temperate south-western Australia. Overall, the nematode species richness recorded in the upstream (38) and downstream estuarine areas (58) and from throughout the estuary (61) were substantially less than in marine waters (75). In addition, the value for Simpson’s diversity index was marginally less in the estuary and the dominance of the most abundant species greater. In contrast, the mean nematode species richness and diversity in individual cores followed the reverse trend, reflecting a combination of less variability among the species compositions and far greater densities in the cores from estuarine sediments. Furthermore, the mean density (numbers 10 cm−2) was far higher in both upstream (341) and downstream (903) areas of the estuary than in marine waters (87). Although the compositions of the assemblages in upstream and downstream estuarine areas differed markedly from each other at the species, genus and family levels, these differences were less pronounced than those between either of these areas and marine waters. The trophic compositions at the moderately sheltered and fully exposed marine sites differed from that in both areas of the estuary, whereas that at the most sheltered marine site was similar to that in the downstream estuarine area, with both containing substantial proportions of epistrate-grazing species. The variations among the species richness, diversity, densities and taxonomic and trophic compositions of nematode assemblages in the sediments of the two estuarine areas and nearby marine waters appear to reflect differences in 1) salinity regimes, 2) extents of exposure to wave action and its related effects and 3) amounts and types of food available to nematodes. 相似文献
12.
The concentrations of rare earth elements in the dissolved, acid-soluble and residual phases in surface waters of the Changjiang
Estuary were determined using ICP-MS. The main purposes of the study are to understand the estuarine geochemistry of rare
earth elements and to explore water-particle interactions in the Changjiang estuarine mixing zone. The results show that there
are two distinct processes operating on dissolved rare earth elements in the estuary: large scale removal at low salinities
due to salt-induced coagulation and remarkable release at mid to high salinities. These processes result in modification of
the effective river water flux and the systematical fractionation of the dissolved rare earth elements toward the East China
Sea. The increase in concentration of dissolved rare earth elements in the mid to high salinity waters of the Changjiang Estuary
suggests a sediment source in the mixing zone of the estuary, which is located over a shallow, broad shelf where there is
extensive physical contact between bottom sediment and estuarine waters. Acid-soluble rare earth elements, the concentrations
of which also dropped sharply in the low salinity region, appear to be controlled by salt-induced coagulation process and
intense deposition of suspended particulate matter in the low salinity region. In the mid to high salinities, all acid-soluble
rare earth element concentrations increase slightly with increasing salinity, suggesting that resuspension of sediments occurred.
In contrast, the residual rare earth element concentrations are relatively constant with salinity variation in the Changjiang
estuarine surface waters. 相似文献
13.
入海河口是河流和海洋生态系统的过渡带,陆源生态敏感因素入海将极大地影响近岸海域的生态状况。因此,入海生态敏感因素监测是海岸带生态保护和生态防灾减灾的重要基础,也是促进海洋经济可持续发展的关键一环。然而,当前我国入海河口生态预警监测系统的建立尚处于起步阶段,与发达国家之间还存在较大差距。文章从入海河口生态状况对海域生态系统健康的影响入手,总结了国内外入海河口海洋生态预警监测技术的发展历程、建设情况和应用方向,探讨了建设入海河口生态预警监测站的生态意义和系统发展方向。 相似文献
14.
Diatom succession and silicon removal from freshwater in estuarine mixing zones: From experiment to modelling 总被引：1，自引：0，他引：1
Estuaries act as filters for land derived material reducing the river input to the coastal zone. Silicon (Si) removal from freshwater which is tightly linked to the growth of diatoms was studied in the estuarine mixing zone where the mixing of freshwater and seawater results in a salinity gradient. Three planktonic diatom species with different origin and salinity tolerance were grown in an artificial salinity gradient. Salinity stress and nutrient depletion led to a specific succession of the three diatoms along the salinity gradient. When available light was increased, diatoms reached higher biomass and the Si removal from water column was more efficient along the mixing. From this experiment, a conceptual model of Si transformations and removal from freshwater was build and applied to an idealized stratified estuary. Sensitivity analysis with varying initial conditions and parameter values pointed transit time of freshwater in the estuary, freshwater and seawater mixing rate and river turbidity as important interactive factors influencing Si removal from freshwater. Other factors like the total amount and the salinity tolerance of diatoms in the upstream river were shown to significantly affect riverine Si removal from the surface layer of an estuary. Finally it appears that Si removal from freshwater in estuarine mixing zones proceeds in two ways: a first rapid death and sedimentation of planktonic stenohaline diatoms imported from the river and second, the growth and subsequent settling of planktonic euryhaline diatoms of either freshwater or marine origin. 相似文献
15.
根据河海划界的可操作性的要求,探讨了海岸地貌学指标在河口区划分中的作用,并通过对河口区与河流、海洋之间的动态联系的阐述,提出河口区管理方式的建议.河口是海岸带陆海相互作用的典型环境,具有物理、化学、地质、生物和环境等多种复杂动力学过程,每一个河口都是高度个性化的.在为数不多的体现河口共性的参数中,海岸地貌学指标可用来确定河口区的内、外边界.根据河流水力学特征和河口过程的可容空间范围特征,河口-河流的分界点可用B-L曲线(B为河岸宽度,L为距离原点沿河流轴线的累积长度)上的拐点位置来表示.而按照河口为"半封闭水域"的定义,河口-海洋分界线可采用围封河口水域的海岸线的包络线.河口水域受到河流和海洋的双重影响,且河口区的自然演化和人类开发活动也会影响河流和海洋.因此,在我国河口区管理上应建立海洋和其他管理部门之间的协调机制. 相似文献
16.
17.
Sources and distribution of organic matter in a river-dominated estuary (Winyah Bay, SC, USA) 总被引：12，自引：0，他引：12
Miguel A. Goi Maria J. Teixeira David W. Perkey 《Estuarine, Coastal and Shelf Science》2003,57(5-6):1023-1048
The sources and distribution of organic matter (OM) in surface waters and sediments from Winyah Bay (South Carolina, USA) were investigated using a variety of analytical techniques, including elemental, stable isotope and organic biomarker analyses. Several locations along the estuary salinity gradient were sampled during four different periods of contrasting river discharge and tidal range. The dissolved organic carbon (DOC) concentrations of surface waters ranged from 7 mg l−1 in the lower bay stations closest to the ocean to 20 mg l−1 in the river and upper bay samples. There was a general linear relationship between DOC concentrations and salinity in three of the four sampling periods. In contrast, particulate organic carbon (POC) concentrations were significantly lower (0.1–3 mg l−1) and showed no relationship with salinity. The high molecular weight dissolved OM (HMW DOM) isolated from selected water samples collected along the bay displayed atomic carbon:nitrogen ratios ([C/N]a) and stable carbon isotopic compositions of organic carbon (δ13COC) that ranged from 10 to 30 and from −28 to −25‰, respectively. Combined, such compositions indicate that in most HMW DOM samples, the majority of the OM originates from terrigenous sources, with smaller contributions from riverine and estuarine phytoplankton. In contrast, the [C/N]a ratios of particulate OM (POM) samples varied significantly among the collection periods, ranging from low values of 5 to high values of >20. Overall, the trends in [C/N]a ratios indicated that algal sources of POM were most important during the early and late summer, whereas terrigenous sources dominated in the winter and early spring.In Winyah Bay bottom sediments, the concentrations of the mineral-associated OM were positively correlated with sediment surface area. The [C/N]a ratios and δ13COC compositions of the bulk sedimentary OM ranged from 5 to 45 and from −28 to −23‰, respectively. These compositions were consistent with predominant contributions of terrigenous sources and lesser (but significant) inputs of freshwater, estuarine and marine phytoplankton. The highest terrigenous contents were found in sediments from the river and upper bay sites, with smaller contributions to the lower parts of the estuary. The yields of lignin-derived CuO oxidation products from Winyah Bay sediments indicated that the terrigenous OM in these samples was composed of variable mixtures of relatively fresh vascular plant detritus and moderately altered soil OM. Based on the lignin phenol compositions, most of this material appeared to be derived from angiosperm and gymnosperm vascular plant sources similar to those found in the upland coastal forests in this region. A few samples displayed lignin compositions that suggested a more significant contribution from marsh C3 grasses. However, there was no evidence of inputs of Spartina alterniflora (a C4 grass) remains from the salt marshes that surround the lower sections of Winyah Bay. 相似文献
18.
Changes in phytoplankton diversity and community composition along the salinity gradient of the Schelde estuary (Belgium/The Netherlands) 总被引：1，自引：0，他引：1
Phytoplankton diversity and community composition were studied along the Schelde river–estuary–coastal zone continuum during the summer of 2003. DCA analysis indicated a gradual compositional turnover of the phytoplankton community within the estuary. GAM modelling of species response curves along the estuarine gradient was used to identify taxa that had their population maximum in the river, the coastal zone or within the estuary. Taxa that had their population maximum within the estuary did not form a homogenous community but comprised species with different salinity optima and rather restricted salinity tolerances. The observed changes in community composition along the estuarine transition zone correspond more closely to an ecocline than to an ecotone model. Despite the fact that few taxa had their population maximum at or near the salinity gradient, alpha diversity did not display a minimum around the salinity gradient. This lack of a diversity minimum within the estuary was ascribed to an important contribution of taxa of riverine or coastal origin to alpha diversity within the estuary contributed. On average 55% of the alpha diversity in the estuarine samples was due to riverine or coastal taxa. Beta diversity displayed a clear maximum around the salinity gradient. For planktonic organisms which are subject to mass effects, beta diversity is probably a better indicator for the impact of the salinity gradient on diversity in estuaries than alpha diversity. 相似文献
19.
This paper demonstrates the importance of advective transport of water through permeable estuarine and salt marsh sediments. This transport delivers significant quantities of radium and barium to the coastal ocean; and, in some cases may remove significant quantities of uranium. These conclusions are based on repeated analyses of seven river–estuarine systems from North Carolina to Florida. Fluxes of radium and barium from these river systems are shown to be inadequate to balance the dissolved inventories of these elements in the South Atlantic Bight. The strong interactions that occur between surface and subsurface waters as these rivers encounter coastal marshes lead us to consider these river mouths as marsh-dominated in terms of their chemical fluxes to the ocean. Such interactions between the river and coastal marsh must be considered when estimating fluxes of material between the land and ocean. 相似文献
20.
Worldwide estuarine ecosystems are by their privileged geographic location, anthropogenically impacted systems. Heavy metal contamination in estuarine waters and sediments are well known to be one of the most important outcomes driven from human activities. The partitioning of these elements has been widely focused, due to its importance not only on the estuarine biogeochemistry but also on its bioavailability to the trophic webs. As observed in other estuaries, in the Tagus basin, no increase in the partition coefficients with the increasing suspended particulate matter concentrations was observed, mostly due to a permanent dilution process of the suspended matter, rich in heavy metals and less contaminated and resuspended bottom sediments. Another important outcome of this study was the common origin of all the analysed heavy metals, probably due to the large industrialization process that the margins of the Tagus estuary suffered in the past, although no relationship was found with the presence of the different discharge areas. In fact, metal partitioning seems to be mostly influenced by the chemical species in which the pollutant is delivered to the system and on water chemistry, with a higher emphasis on the metal cycling essentially between the particulate and dissolved phase. This partitioning system acquires a relevant importance while evaluating the impacts of marine construction and the associated dredging operations, and consequent changes in the estuarine water chemistry. 相似文献