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1.
青藏高原东部兴措湖壳体同位素记录的气候环境信息 总被引：2，自引：0，他引：2
吴敬禄 《海洋地质与第四纪地质》2001,21(4):19-23
通过对青藏高原东部兴措湖Gyraulus sibirica壳体同位素的分析，并将其与器测气象资料进行相关研究，建立了兴措湖同位素记录与对应的降水和气温间的函数关系。结果表明，青藏高原东部兴措湖地区腹足类生物在夏半年形成壳体，它所记录的是夏半年而不是全年的气候环境信息；Gyraulus sibirica壳体δ^16O指标与夏半年温度滑动平均为明显的正相关关系，相关系数为0．89，平均变率为1．64‰／℃，均值比为0．28‰／℃；δ^13C指标与夏半年的水量呈正相关关系，相关系数0．71，平均变率为0．027‰／mm。 相似文献
2.
青海湖沉积物有机碳含量与同位素和粒度特征及其古气候意义 总被引：15，自引：5，他引：15
对青海湖沉积物中粒度参数、总有机碳（TOC）含量及其δ^13C值的形成条件与环境气候的关系进行了研究。结果表明：在暖湿时期，沉积物中有机碳含量（TOC）较高，有机质的δ^13C值较高，沉积物的平均粒径较细；反之，在冷干时期，沉积物中有机碳含量（TOC）较低，有机质的δ^13C值较低，沉积物的平均粒径较粗。反映出沉积物中TOC含量、有机质δ^13C值及粒度特征与气温具有良好的相关性。结合^14C测年，分析了湖区古气候演化序列，表明自8500aBP以来湖区气候经历了4个演化阶段：即暖湿－凉干－温湿－冷干的变化过程。 相似文献
3.
南海南部水体和沉积物中的浮游有孔虫氧碳同位素分析 总被引：2，自引：0，他引：2
通过对2002年南海南部春季水体和表层沉积物中浮游有孔虫的δ^18O和δ^13C分析，初步探讨该区有孔虫氧碳同位素的海洋环境指示意义及其与沉降过程的关系。结果表明，南海南部春季表层水体中Gltbigerinoides ruber （G．ruber）与Globigerinoides sacculifer（G．sacculifer）的δ^18O均值基本相似，相对它们在表层沉积物中的δ^18O明显要小；但在表层沉积物中G．ruber的δ^18O则比G．sacculifer相对要小0．34‰。这种差异可能与G．sacculifer的配子生殖二次钙化以及2个种属的季节性差异有关。Pulleniatinaobliquiloculata（P．obliquiloculata）的δ^18O在沉积物和水体中均较G．ruber和G．sacculifer明显偏大，表现出较大的种间差异。P．obliquiloculata的δ^18O在春季水体中比其在沉积物中平均约小0．7‰，差值较大，可能是因为P．obliquiloculata为冬季种，主要出现在冬季低温水体中。3种浮游有孔虫的δ^13C以G．sacculifer最大，G．ruber次之，P．obliquiloculata最低，这种差异可能主要由属种间的生命效应所引起。表层沉积物中G．ruber和G．sacculifer的δ^18O从区域的西北往东南有逐渐变小的趋势，可能受区域年均表层水温西北低东南高的影响。在上升流发育区，P．obliquiloculata的δ^18O和δ^13C均明显偏高，其δ^13C与水体营养的关系与南海北部的明显相反，有待进一步深入研究。 相似文献
4.
62kaBP以来湖光岩玛珥湖沉积物有机碳同位素记录及古气候环境意义 总被引：18，自引：1，他引：18
湖光岩玛珥湖HUG-B孔岩心记录了62kaBP以来的古气候、古环境变化信息。全岩有机碳同位素组成(δ^13CTOC)分析表明，62kaBP以来δ^3CTOC值变化比较明显，其变化范围为-28．5‰～-15．5％0。结合孢粉和有机地球化学指标进行综合分析，湖光岩玛珥湖δ^13CTOC变化曲线可划分为6个演化阶段：62～58和48～40．5kaBP两个时段的δ^13CTOC值偏负，沉积物中有机质主要来源于热带-亚热带地区的陆生C13森林植被，反映了温暖潮湿的气候环境；58～48和40．5～17．2kaBP期间δ^13CTOC值明显偏正，沉积物中有机质主要源自C4草本植物，反映了湖光岩地区有效降水量减少、干旱程度增加导致湖光岩玛珥湖湖面下降，大量C4草本植物生长在暴露的湖滨岸；17．2～4kaBP时段内δ^13CTOC值尽管存在更加频繁的波动，但总体呈现逐渐偏负的趋势，反映了暖湿和冷干气候多次交替但总体上逐渐变暖、变湿的气候环境；4kaBP以来δ^13CTOC值存在逐渐偏正的趋势，虽然不排除人类活动的影响，但很可能反映了干旱程度的再次增加。综合分析表明，有效降水量(降水量-蒸发量)是控制湖光岩玛珥湖地区C3／C4植物相对生物量变化的主导因素。湖光岩玛珥湖有机碳同位素的研究结果支持区域气候环境而不是大气CO2浓度变化是末期冰期以来热带低纬度地区C3／C4植被相对生物量变化的主要原因。 相似文献
5.
环渤海地区河流河口及海洋表层沉积物有机质特征和来源 总被引：4，自引：0，他引：4
2013年8月采集了环渤海地区35条主要河流河口表层沉积物样品,12月采集了渤海与北黄海24个表层沉积物样品,分析了其生物地球化学指标:总有机碳(TOC)、总氮(TN)、有机碳同位素(δ13C)和氮同位素(δ15N),探讨该区域表层沉积物有机质特征及组成。研究表明:河流河口表层沉积物有机碳同位素(δ13C)值在–26.4‰—–21.8‰,平均值为–24.5‰;渤海表层沉积物有机碳同位素(δ13C)值在–23.8‰—–21.7‰,平均值为–22.3‰。河口表层沉积物TOC含量在0.06%—3.87%,平均值为1.31%;渤海表层沉积物TOC含量在0.52%—2.09%,平均值为1.08%。河流δ13C富集较轻,偏向陆源;海洋δ13C富集较重,偏向水生有机质来源。河流河口表层沉积物的δ13C值差异较明显,最大值与最小值相差4.6‰,但是流域地理位置距离近的河流δ13C值差异不大。河流河口表层沉积物δ15N在1.5‰—10.2‰,平均值为5.5‰;渤海表层沉积物δ15N在4.4‰—5.6‰,平均值为5.0‰。河流表层沉积物δ15N范围比渤海表层沉积物δ15N范围广,原因是河流受陆源有机物影响,且陆源有机物来源差异大。海洋表层沉积物δ15N相对均一,说明海洋表层沉积物δ15N受物源影响较小,体现了水体中有机质的转化和微生物活动对氮同位素的影响。本研究中表层沉积物的δ13C与δ15N没有明显的相关性,也体现了陆源有机质输入的影响。根据经典的二元模式计算,35条河流陆源有机质的贡献比例范围为10%—90%,平均值为60%;渤海陆源贡献比例范围为10%—50%,平均值为20%。河流有机质的来源以陆源有机质为主,水生有机质为辅。渤海有机质的来源以水生有机质为主,环渤海河流的陆源输入也有重要贡献。需要指出的是,有机碳同位素(δ13C)、氮同位素(δ15N)和Corg/Ntotal对有机质来源判别有一定局限性,虽然稳定同位素有示踪性,然而其成分仍然不可避免地受到生物地球化学等过程的改造,在使用稳定同位素技术示踪物源时,须小心谨慎。 相似文献
6.
南海北部浅表层沉积底栖有孔虫碳同位素及其对富甲烷环境的指示 总被引：3，自引：0，他引：3
对南海北部陆坡东沙海域、神狐海域及西沙海槽甲烷渗漏环境和无甲烷渗漏环境87个浅表层沉积物中的底栖有孔虫Uvigerinaspp.进行碳同位素分析研究,结果表明,东沙海域δ13C值为-0.52‰~-5.68‰,平均值为-1.41‰,出现明显的负偏移;神狐海域δ13C值介于-0.36‰~-1.10‰,平均值为-0.75‰,未见明显的δ13C值负偏移;西沙海槽δ13C值介于-0.01%~-0.89‰,平均值为-0.45‰;对Uvigerinaspp.碳同位素组成与沉积物有机碳(TOC)、甲烷(CH4)间的关系进行探讨,发现δ13C负偏移主要出现在甲烷渗漏环境,发生在末次盛冰期,与溶解无机碳负偏移以及沉积物全样的δ13C值负偏移层位相吻合,有可能作为富甲烷环境的替代指标。 相似文献
7.
珠江口不同沉积有机质的来源及相对含量 总被引：4，自引：1，他引：4
通过分析珠江口表层沉积物的C、N元素及C、N稳定同位素，发现其总有机碳(TOC，干重％)含量为0．06％-1．02％，其中深圳湾-内伶仃岛-澳门和珠海附近海域及香港、大亚湾附近海域表层沉积物中的TOC含量较高。总氮(TN，干重％)含量为0．03％-O．19％，TOC和TN的比值范围为1．36-7．84，反映了沉积有机质的混合来源。沉积物的^15N值为3．86‰-6．39‰，δ^13Corg值为-24．76‰--21．98‰，表明珠江口的沉积有机质主要来源于海洋有机质和陆源有机物。从河口向西，δ^13Corg值偏轻，表明由河流带入的陆源有机质受科氏力作用主要在珠江西岸沉积。 相似文献
8.
对2003年7月至9月采自北极楚科奇海域的4个站位表层沉积物及1个站位的柱状沉积物样品的总糖、总碳、有机碳、无机碳、总氮、总磷的含量进行了测定,并对其有机碳和有机氮同位素(1δ3C和1δ5N)的变化进行了研究,结果表明:北极楚科奇海域沉积物中的总糖与有机碳为明显的正相关关系,说明糖类是有机碳重要的组成部分;表层沉积物中TOC/TN平均值为9.273,1δ3C和1δ5N的平均值分别为-21.61‰和7.1‰,显示出表层沉积物中糖类物质以海洋藻类来源为主、混入部分陆源物质的分布特征;柱状样品不同深度沉积物中TOC/TN平均值为13.45,也反映出糖类物质为海洋自生和陆源输入共存的分布特征。 相似文献
9.
2005年8月在海南洋浦湾内湾取得1根柱状样,在铅-210定年的基础上分析沉积物粒度、总有机碳含量及其同位素值(δ13C)、总氮含量及其同位素值(δ15N)、生物硅含量、重金属(镍、镉、铬、铜、锌、铅)含量及有机氯农药(六六六、滴滴涕)含量等参数发现,111cm至表层,沉积物中有机碳、总氮、生物硅含量升高,特别是从45cm至表层,它们的含量明显增加,说明该湾内有富营养化趋势。由有机碳与总氮的原子比和有机碳同位素指示的物源信息可知,该湾内有机质来源为藻类和陆源脉管植物的混合,且以陆源输入为主。陆源有机碳含量与总有机碳含量的相关系数为0.917。自23cm至表层有机碳同位素明显偏轻,氮同位素偏重。从111cm至表层,重金属和有机氯农药含量升高。综合分析各环境指标可知,洋浦湾近百年来环境演变可分为三个时期,即20世纪70年代以前、70年代至90年代、90年代至21世纪初,洋浦湾经历了未污染期、轻度污染期、显著污染期。 相似文献
10.
稳定同位素在天然气水合物地球化学勘查中的应用简介--以"布莱克海隆"海区为例 总被引：2，自引：0，他引：2
介绍了国外在布莱克海隆（包括ODP164航次994、995、997站位）进行天然气水合物勘查过程中应用稳定同位素的研究实例；通过对这3个站位样品的甲烷、CO2、DIC（dissolved inorganic carbon)、有机碳以及自生碳酸盐的δ^13C分析，指出浅部（0－30m)甲烷和DIC的δ^13C值随深度迅速降低又迅速升高的变化可以作为天然气水合物存在的地球化学指标。994站位孔隙水δ^18O值深度从0.30‰下降到-0.37‰；氢同位素δD随深度略有下降（从11‰到-12‰），这与水合物形成时氢氧重同位素相对富集于固相有关，表明天然气水合物的存在。997站位δ^37Cl从海底沉积物表层以下30m处为接近海水的最大值0，至钻孔底746.85m处降为-3.68‰，可能也与天然气水合物的形成有关。 相似文献
11.
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
12.
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
13.
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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15.
《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
16.
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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18.
Coastal inundation associated with extreme sea levels is the main factor which leads to the loss of life and property whenever a severe tropical cyclonic storm hits the Indian coasts. The Andhra and Orissa coasts are most vulnerable for coastal inundation due to extreme rise in sea levels associated with tropical cyclones. Loss of life may be minimized if extreme sea levels and associated coastal flooding is predicted well in advance. Keeping this in view, location specific coastal inundation models are developed and applied for the Andhra and Orissa coasts of India. Several numerical experiments are carried out using the data of past severe cyclones that struck these regions. The simulated inland inundation distances are found to be in general agreement with the reported flooding. 相似文献
19.
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
20.
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