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1.
长江河口淡水端溶解态无机氮磷的通量 总被引：15，自引：1，他引：15
1998年2和9月在长江河口淡水端连续观测了DIN(NO3-,NO2-,NH4+),PO43-,流速和流向.结果表明,溶解态无机氮、磷浓度的时空变化较复杂;1998年2月NO3-,NO2-,NH4+和PO43-的月通量分别为168241,974.4,19335和2648t,9月的月通量分别为905678,8317,5797和6281t;1998年NO3-,NO2-,NH4+和PO43-年通量分别为497.1×104,3.911×104,10.22×104和4.155×104t. 相似文献
2.
以无性繁殖系为材料,开展了缘管浒苔和羽藻对NO3-,NH4+和PO43-的吸收动力学、生长动力学研究。吸收动力学研究结果表明缘管浒苔和羽藻对NO3- 和PO43-的吸收方式为主动运输,对NH4+的吸收方式为被动扩散。缘管浒苔对NO3-的最大吸收速率(Vmax)、对NH4+的吸收斜率都大于羽藻,说明缘管浒苔对高浓度的NO3-和NH4+具有更强的吸收能力。缘管浒苔吸收NO3-和NH4+的a值远大于羽藻,说明在低营养盐浓度时,缘管浒苔对NO3-和NH4+的亲和力更强。在PO43-的吸收中,羽藻的最大吸收速率(Vmax)远大于缘管浒苔,说明羽藻对高浓度PO43-的吸收能力更强,但缘管浒苔的a值远大于羽藻,说明前者在低营养盐浓度时PO43-的亲和力更强。生长动力学研究结果表明,硝酸氮是促进两种海藻快速生长的最适宜氮源形式,氨氮更易促进藻体叶绿素的积累。在相同氮营养条件下,羽藻表现出比缘管浒苔更强的生长优势。 相似文献
3.
珠江口夏季水体中的氮和磷 总被引：19，自引：0，他引：19
根据1999年7月17～28日于珠江口现场调查和实验的资料,研究夏季水体中氮、磷的分布、形态变化和初级生产力的限制因素.结果表明该海域氮含量高,N/P属于世界上高值区之一.从河口向外海运输过程中,氮和磷的形态和浓度均有剧烈的变化.虽然氮在中途中有新源的补充;但由于外海水的入侵稀释、生物吸收和形态变化的迁移作用,NO3-和可溶无机氮的浓度总的变化趋势仍是随盐度增大而大幅度地降低,以至珠江口外出现N/P低于16.由于夏季水体层化稳定,在表、底层其生物地球化学变化方向相反,PO43的浓度变化互成镜像关系并可按盐度分为3段不同特征的反应区.初级生产力的限制因素在大部分区域是磷,但从口门至最大浑浊带和口外区则分别是浊度(或光照)及可溶无机氮.现场培养实验再现了真光层和底层氮和磷的生物地球化学过程差异并表明磷的循环和再生比氮迅速;在可溶无机氮浓度大且高N/P的海域,磷的再生可成为水华的引发因素,而氮被耗尽却是水华消亡的原因.总体上夏季该区水体氮的迁出率比磷高.于水体层化稳定的区域,氮和磷的生物地球化学作用在真光层以浮游生物吸收占优势、在下层以有机物的降解和可溶无机态的再生为主,当层化消失、上下水体充分混合则可完成循环. 相似文献
4.
于2007年5月份(枯水期)和8月份(丰水期)采集辽河口区域大气样品及水样,应用气相色谱及静态顶空法测定大气及海水中溶解N2O的浓度,并计算不同站位的N2O通量。结果表明:辽河口区域水体中溶解N2O浓度存在着明显的时空变化,5月份河口区域水体中N2O浓度高于8月份,且河流段溶解N2O浓度大于近海岸海域。水中溶解N2O浓度及溶解氧浓度呈显著的负相关关系。在枯水期和丰水期,所有站位的N2O均处于过饱和状态,N2O气体从水体向大气排出,辽河口区域是大气中N2O的一个排放源。 相似文献
5.
辽河口沉积物反硝化过程研究 总被引：1，自引：0，他引：1
近年来，辽河口沿岸人类活动频繁，工农业活动发达，大量的氮、磷等营养物质输入至感潮河段继而排放入海，导致辽河口水体富营养化程度加剧。沉积物区域是反硝化作用的重要发生地和微生物富集地。微生物能够将沉积物中的硝酸盐及亚硝酸盐还原为N2O和N2释放到大气中，进而减轻河口生态系统氮负荷。本文中的实验采用定量PCR技术测定辽河口表层沉积物反硝化过程功能基因narG、nirK、norB、nosZ的基因丰度，结果表明，主导硝酸盐还原的narG功能基因丰度最高。使用高通量测序技术对nirK型功能基因进行测序，结果显示，在辽河口反硝化细菌中Devosia、Phaeobacter、Alcaligenes、Pseudomonas菌属丰度较高。反硝化功能基因的丰度主要受到沉积物粒径的影响，norB基因丰度与多个环境因子显著相关。nirK型反硝化细菌的群落结构和多样性主要受盐度、pH、溶解氧以及NO2?的影响。研究分析了反硝化功能基因丰度和细菌群落结构及其主要影响因子，其结果为辽河口水体富营养化中氮元素归趋的认知提供理论依据。 相似文献
6.
台湾海峡上升流区氮、磷、硅的化学特性及输送通量估算 总被引：10，自引：1，他引：10
台湾海峡中北部海域1983～1984年、1987～1988年多次调查资料表明,夏季氮、磷、硅诸营养盐呈近岸、底层高,向上层、外海递减的分布特征,其控制因素是福建近岸上升流。该上升流区NO3--N、PO43--P、SiO32--Si的特征值分别为2.29、0.20、2.83μmol/dm3.诸营养盐含量与温度、盐度溶解氧含量及其饱和度有明显的相关性。N/P比平均值接近于Redfield比值。PO43--P、NO3--N、SiO32--Si垂直输送通量分别估算为23.6、223、302mg/(m2·d),是该海域夏季营养盐的主要来源,PO43--P和NO3--N的输送通量平均分别大约为真光层生物生产力所需营养盐的86%和73%. 相似文献
7.
海洋中生源活性气体的来源与迁移转化 总被引：1，自引：1，他引：0
海洋生源活性气体主要包括二甲基硫（DMS）、甲烷（CH4）、氧化亚氮（N2O）、一氧化碳（CO）、挥发性卤代烃（VHCs）和非甲烷烃（NMHCs）等。它们通过海-气交换进入大气，不仅在全球碳、氮和硫循环中发挥关键作用，而且会直接或间接地对环境和气候变化产生重要影响。海洋释放的活性气体一类属于温室效应气体（CH4、N2O、VHCs和CO等），另一类会在大气中发生化学反应，控制着大气氧化平衡和臭氧浓度（VHCs和NMHCs）。而DMS属于负温室效应气体，其在大气中被快速氧化形成硫酸盐气溶胶，进而对云的形成和辐射强迫产生重要影响。本文综述了国内外海洋生源活性气体的研究现状，着重介绍了DMS、CH4和N2O的来源、迁移转化、海-气通量及其影响机制，并指明了该领域存在的科学问题及今后的研究方向。 相似文献
8.
夏季南黄海颗粒氮同位素分布特征及影响因素研究 总被引：1，自引：0，他引：1
黄海是人类活动影响显著的半封闭陆架边缘海，在夏季存在特征鲜明的冷水团结构。为研究南黄海颗粒态氮的循环转化过程，本文通过分析2016年夏季南黄海水体颗粒物和表层沉积物的碳、氮含量及同位素，探讨南黄海近岸海域和冷水团海域颗粒物和表层沉积物氮含量、同位素的分布差异和影响因素。近岸海域颗粒氮(Particulate Nitrogen，PN)呈现出含量较高、氮同位素值(δ15NPN)垂向差异较小、沉积物总氮(Total Nitrogen，TN)含量较低且氮同位素值(δ15NTN)偏负的分布特征；冷水团海域PN呈现出含量低、δ15NPN垂向差异显著、沉积物TN含量高且δ15NTN偏正的分布特征。通过海底边界剪切应力模拟、环境因子分析并结合颗粒物与沉积物δ15N示踪分析，发现南黄海海域颗粒态氮及同位素分布主要受到水体/底边界动力过程影响，陆源输入和矿化过程亦共同参与调控。 相似文献
9.
大亚湾营养物质变异特征 总被引：38，自引：0，他引：38
利用大亚湾现场调查和室内模拟数据,以及大亚湾生态网络17～18年8个航次的现场调查资料,采用营养状态质量指数(NQI)的方法评价大亚湾海域富营养化水平,结果表明,大亚湾海域除部分养殖海区为中营养状态外,大部分为贫营养状态;溶解态的无机磷和硅在过去10a多有较大幅度的下降,而溶解态的无机氮、溶解氧和叶绿素a则上升;浮游植物生长由过去认为由氮控制转变为现在由磷控制.分析了养殖海区底层海水、上覆水、沉积物间隙水中营养盐的含量及其化学形态.估算了沉积物-海水界面营养盐扩散通量,NH4+,NO2-,NO3-,HPO42-,H4SiO4平均通量分别为302.0,-0.06,-1.82,2.53,47.6μmol/(m2·d).室内模拟了天然海水体系表层沉积物营养盐的吸附-解吸及其磷酸盐在沉积物上的吸附等温线.论述了大亚湾海域营养盐与赤潮的关系. 相似文献
10.
长江口及邻近海区营养盐结构与限制 总被引：5，自引：0，他引：5
通过研究长江口及邻近海域溶解无机氮(DIN=NO3-+NO2-+NH4+)、磷酸盐(PO43-)、硅酸盐(SiO32-)所表征的营养盐区域结构特征及影响因素,在分析营养盐绝对限制情况的基础上,划分了潜在相对营养限制区域。结果表明,123°E以西近岸表层区域DIN/P比值全年均高于16,而Si/DIN除秋季外基本小于1,显示出长江冲淡水影响下"过量氮"的特征。春夏季河口锋面区(31°~32.5°N,122.5°~124°E)硅藻的大量生长可使DIN/P异常升高和Si/DIN异常降低。秋季研究区域北部DIN/P西低东高且Si/DIN西高东低是由于在高DIN、低PO43-的长江冲淡水影响下,近岸受相对低DIN、高SiO32-的苏北沿岸流南下入侵影响而被分割而成。冬季长江口门东北部存在的高DIN/P和低Si/DIN区则主要由于寡营养盐的黑潮水深入陆架,向东北输送的部分长江冲淡水和增强的苏北沿岸流共同作用造成DIN升高所致。利用Redfield比值进行了不同站位表层潜在相对营养限制情况的区分。近岸123°E以西受高DIN、SiO32-长江冲淡水影响,四季多呈现PO43-潜在相对限制,而在春夏季由于浮游植物的大量吸收PO43-,造成局部PO43-绝对限制及潜在相对限制。春夏季氮限(DIN潜在相对限制)一般发生在外海部分站位,但较为零散。秋季除了东南外海大部分站位外,受苏北沿岸流影响在长江口北部近岸也存在氮限。随着低DIN/P的黑潮表层水(KSW)的入侵加强,冬季外海氮限站位增多。硅限(SiO32-潜在相对限制)在夏季发生在赤潮高发区,而冬季南部存在较多硅限站位表明KSW中SiO32-相对较为缺乏。 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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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
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