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通过分析苏干湖地区降尘(含尘暴样品)、湖泊表层沉积(碎屑沉积)以及湖泊东部地表沉积3组样品的元素组成特征发现:3组样品具有同源性,Al和Ti在粉尘释放—沉积中行为稳定,Fe可能受元素分馏效应的影响,在湖泊沉积中富集程度相对较高。6次典型尘暴特征分析结果表明,尘暴降尘中Al、Fe、Ti通量的变化与尘暴发生期间10 min平均风速及其变差系数(Cv)间存在显著的相关关系。Al、Fe、Ti通量不仅可以作为尘暴中风速变化的替代指标,而且可以指示尘暴事件中风速的变化幅度。苏干湖现代沉积(岩心)中Al、Fe、Ti通量变化与冷湖气象站44年的年均大风日数记录具有较好的一致性。因此,可以利用湖泊现代沉积中风成输入碎屑组分(去除有机质和碳酸盐)的Al、Fe、Ti通量作为大风尘暴事件的替代指标,以重建地质历史时期柴达木盆地粉尘源区尘暴演化序列或者粉尘释放历史。 相似文献
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南海湖泊沉积物中的陆源粉尘记录 总被引：1，自引：0，他引：1
对采集于南海西沙东岛"牛塘"的湖泊沉积柱(DY6)进行元素、粒度、显微成像、扫描电镜及场发射能谱分析。元素分析结果表明,Ti、Al元素在沉积柱中的含量远高于3个主要沉积端元(珊瑚砂、鸟粪和植物),具有外源的特征,在Ti和Al的高值层位中存在较多不溶于酸的粉尘颗粒,与春季合肥地区收集到的北方风尘颗粒形貌特征相近,粒径相对较小,也与季风携带沉降于朝鲜半岛和南海北部海域的风尘形貌相似;X射线能谱分析结果显示,这些粉尘颗粒物成分以硅酸盐岩和石英为主,很可能是东亚冬季风携带下源自亚洲大陆的沉积;沉积物中Ti和Al的含量变化可以用于指示历史时期南海中北部海域陆源粉尘颗粒的沉降通量。 相似文献
3.
湖泊沉积物中色素的研究及其环境指示意义 总被引：6，自引：0，他引：6
湖泊沉积物作为揭示古环境、古气候变迁的最佳载体,它完整地记录了地质历史时期区域气候、植被以及人类活动的演化轨迹。而沉积色素是研究湖泊沉积的重要代用指标,它们对于重建区域初级生产力、反演区域生态环境提供了有用的信息。本文在综述国际上生物色素在湖泊沉积中研究进展的同时,着重阐述了它们在湖泊沉积物中的保存、生物输入源的识别以及对区域生态环境变化的响应等方面的研究动态;讨论了色素在利用湖泊沉积研究环境变化方面的发展前景,指出随着分析技术的发展,沉积色素将在重建古气候、古环境演化方面具有优势。 相似文献
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经野外取样和地球化学测试分析,即墨温泉喷流沉积物呈现元素的富集并形成Fe,Ba,Li,La,Ce,Sc等10种元素的正异常.喷流沉积物中的Fe/Ti,(Fe Mn)/Ti及Al/(Al Fe Mn)比值分别为22.63,22.76和0.36～0.39,具有高铁低铝的热水沉积地球化学标识特征,符合Bostrom K.的热水沉积的标识;越流沉积物呈现诸多元素的亏损与负异常;越流沉积的Fe/Ti,(Fe Mn)/Ti及Al/(Al Fe Mn)比值仅为5.91,5.97和0.65,不具备热水沉积标识特征;通道-喷口沉积物呈现元素的富集并形成La,Ce,Sc,Sr元素的正异常.通道-喷口沉积中的Fe/Ti,(Fe Mn)/Ti及Al/(Al Fe Mn)比值分别为17.14,17.26和0.42,与＞20,＞20±5,＜0.35比值比较,基本具备热水沉积特征,符合Bostrom K的热水沉积的标识.根据上述地球化学标识特征,结合温泉沉积的沉积学、矿物学标识,将即墨温泉沉积物划分为喷流相沉积、越流相沉积和通道-喷口亚相沉积并阐述其 "盆下源"沉积模式. 相似文献
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本文测定了取自黄海南部和东海北部的某些表层沉积物主要元素的含量.根据主要元素的丰度、概率分布及其共生组合得到下列结果: 1.Al、Fe、Mg、Na、K的高含量分布地区与粘土沉积物相一致.Si的高含量区与砂质沉积相一致.Ca的高含量区与生物碎屑沉积物相一致; 2.Al与K、Mg、Na、Fe呈正相关.Mg与Fe之间,Si、P和Al之间也是正相关,Ca和Mn与Al没有明显的关系; 3.沉积物中Al、Fe、Mn、Mg、Na、K和P的含量随着远离海岸和海水深度增加趋于降低,Ca的变化没有规律。相反,在东海北部随着水深Ca含量增加,而Si与水深没有明显关系; 4.黄海沉积物来源于黄河,东海北部沉积物来自长江。 相似文献
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东太平洋海隆13°N附近沉积物岩心地球化学特征 总被引：2，自引：0，他引：2
对东太平洋海隆(EPR)13°N西侧2个沉积物岩心进行了碳酸盐、常量和微量元素测定。沉积物中Fe和Mn的含量较高,其中,E271站位沉积物岩心中Fe含量8.5%~13.8%,Mn含量1.7%~3.17%;E272站Fe含量6%~13%,Mn含量0.12%~3.31%,显示在EPR 13°N热液活动区西侧25~45 km处热液柱对沉积作用的影响明显。E271和E272站位CaCO3含量分别为5.9%~27.57%和6.67%~38.20%。热液柱的沉积作用,使Cu、Pb和Zn在沉积物中富集,Cu/Fe、Pb/Fe和Zn/Fe比值低于热液喷口处的颗粒物中值,Pb表现出在海水中运移距离较短或者只有少量Pb随热液柱扩散运移。热液柱在E271和E272站位的沉积作用使得Li、Mo和Ni在沉积物中富集,此外,V因为铁氧化物颗粒吸从海水中吸附并沉降到沉积物中。沉积物中Ti和Al有非常好的相关性,其Ti/Al比值为0.05左右,与太平洋深海沉积相比具有更高的铁含量,而U在岩心中的含量与深海沉积相似。 相似文献
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近百年来长江中游网湖沉积物粒度特征及其环境意义 总被引：2，自引：0，他引：2
通过放射性核素137Cs和210Pb精确计年,建立了长江中游原通江湖泊网湖近代沉积物年代序列。运用沉积物粒度指标分析了近100年来网湖沉积记录的环境特征,结果表明,近100多年来网湖沉积速率较大,平均约为0.56cm/a;沉积物粒度指标变化与流域降雨量、人类活动以及长江洪水密切相关,降水大的年份和大洪水时期沉积物粒径增大,分选性变差,峰态变宽。根据沉积物粒度指标特征,近100年来网湖沉积环境大致可分为两个阶段:(1)20世纪50年代以前,湖泊沉积主要受降水和洪水等自然因素控制,沉积物粒度组合变化相对较小,在湖泊水动力条件变化时沉积物粒度指标出现明显的波动,反映了流域降水及长江洪水对湖泊沉积环境的影响。(2)20世纪50年代以后,湖泊沉积物平均粒径较大且分选性差,与流域强烈的人类活动所引起的大量陆源碎屑进入湖泊有关,湖泊沉积粒度指标主要反映了流域工农业生产的快速发展、人口的持续增长以及水利工程建设等人类活动对湖泊沉积环境的影响。 相似文献
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堆积在湖泊、港湾的沉积物保留了沉积物来源及人类活动影响的信息,通过对沉积物和区域自然、社会经济环境的研究可以了解自然过程及人类活动对环境变化的影响,作出环境变化的预测[1],为区域生态、环境保护和改善以及区域经济建设决策提供科学依据.铅-210具有特定的核性质(衰变类型、半衰期、衰变能量等)和地球化学行为[2],是百年时间尺度沉积物纪年的良好示踪剂[3~4],已被广泛应用于湖泊、海湾及河口等工业革命以来沉积过程的研究,并反映出较好的计年结果[5~13].本文利用铅-210对厦门杏林湾现代沉积速率进行了研究,并对比了不同时期的地形图,同时结合区域历史沿革来探讨其影响因素. 相似文献
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Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
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The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
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《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
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The relationship between the flux of exotic benthic foraminiferal tests (i.e. tests which are supplied from open-sea sources alone) in a tidal inlet and that of bulk sediment was analysed, which can be expressed as two first-order linear equations. According to this relationship, in order to determine net sediment transport directions in the entrance, the test concentration in surficial sediments of the tidal basin can be compared against a ‘ critical level ’. The critical level is determined for the conditions that no net transport of bulk sediment is present within the entrance. If the observed concentration (averaged over the tidal basin) is higher than the simulated critical level, then the net sediment transport is directed to landward. This method is applied to the analysis of net sand transport at Christchurch Harbour, a tidal inlet system located in southern England. In this investigation, concentrations of exotic foraminiferal tests in the surficial sediments of the tidal basin and ebb tidal delta area were obtained from the analysis of sea-bed sediment samples. A series of probable critical levels were calculated based upon the data sets with regard to: (1) sediment discharge from the rivers; (2) magnitude of sediment discharge within the entrance during the ebb; (3) the test concentration outside the harbour; (4) the thickness of the moving layer; and (5) two parameters associated with dispersive processes. The results show that the concentration in the tidal basin sediment is higher than a number of simulated critical concentrations for representative cases. Consequently, the high level of the concentration of exotic benthic foraminiferal tests within the harbour should be explained as a result of landward net transport of sands within the entrance. 相似文献
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The behaviour of an axially pre-loaded cylindrical member of an offshore structure, hit by a supply ship, has been investigated. The effects of axial pre-loading on the dynamic properties of members, the extent of damage and propagation of dynamic instability in the tubular members have also been investigated. Numerical models have been validated using available experimental data from the literature although these are mostly static with no pre-loading. Axial pre-loading was found to change the dynamic characteristics of some cylindrical members quite dramatically while it had no significant effect on others. The study examined whether there was any change in the behaviour between local and global modes when the loading was dynamic rather than static. The effect of damping on the dynamic instability of axially pre-loaded tubes under lateral dynamic loads was also studied. It was observed that for some geometries the quasi-static response can be used to define the boundary between bounded and unbounded dynamic responses. The main contribution of this study, compared with previous investigations reported in the literature, is that both pre-loading and dynamic effects have been included. 相似文献
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Rahul Sharma 《Marine Georesources & Geotechnology》2000,18(3):237-250
Observations on seafloor features from subbottom profiling and seabed photography data show that the undisturbed and natural conditions before the benthic disturbance undergo a substantial change after operation of the disturber. The effects can be seen in the form of deep trenches and grooves, formed by the action of the sleds and the pumping of the sediment along its path, as well as sediment piles on either side of the track. Biological traces such as fecal coils, casts, tubes, burrows, and trails get obliterated in the areas of disturbance and resedimentation. The smooth, uniform nature of the seafloor observed in predisturbance phase shows microtopographic changes in and around the disturbed area as a result of sediment excavation and resettlement. Vertical mixing as well as lateral transport of sediment alter the geological, biological, physical, and chemical conditions on the seafloor, which need to be monitored over time to assess the process and the time taken for restoration of environmental conditions. 相似文献
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Vance P. Vicente 《Marine Ecology》1989,10(2):179-191
Abstract. Long-term changes in the distributional patterns of commercial sponges ( Spongia spp. and Hippospongia spp.) within the West Indian Region indicates that: 1) commercial sponges had a widespread distribution throughout the whole West Indian Region and were ubiquitous in very shallow water until about the first half of the present century; 2) they were fished commercially not only in the traditional northern Caribbean sites (Florida, Gulf of Mexico, Bahamas) but also in the Greater ( e. g. , Hispaniola, Jamaica) and Lesser Antilles; and 3) they became extinct throughout most of the Lesser Antilles ( e. g. , Puerto Rico, Vieques, St. Thomas) sometime during the first half of this century. Mortalities of spongiids within the Antilles were found to differ from other marine mortalities in that: 1) species disappeared from a large region; 2) species vanished from different habitats and depths; and 3) natural populations never recovered. Species richness patterns suggest that commercial sponge genera ( Spongia and Hippospongia ) evolved under slightly cooler elimatic conditions than those found at present, and that these extinctions occurred as a direct or indirect effect of positive thermal anomalies in sea surface and atmospheric temperatures between 1900–1950. The concept that species diversity is stable on a regional scale is questioned. 相似文献