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1.
莫桑比克海峡及其邻近海区是全球海洋潮流和潮能耗散最强的海区之一。文章利用高分辨率通用环流模式对该海区的正压潮流进行模拟, 并对该海区潮能通量和潮能耗散特征进行分析。结果表明, 莫桑比克海峡及其邻近海区的潮波主要是半日分潮占主导地位, 全日分潮可忽略不计, M2分潮形成1个左旋潮波系统和1个右旋潮波系统, S2分潮形成1个左旋潮波系统。莫桑比克海峡和马达加斯加岛南部等绝大数区域的M2和S2半日潮流是逆时针旋转, 在马达加斯加岛顶部等局部区域是顺时针旋转, 而且在海峡通道等复杂地形处潮流流速量级较大。潮能通量矢量主要来自东边界, 大部分潮能通量沿马达加斯岛北部传入莫桑比克海峡区域, 其中经过马达加斯加岛北部和进入莫桑比克海峡的M2 (S2)分潮的潮能通量分别为156.86GW (40.53GW)和148.07GW (36.05GW), S2分潮潮能通量的量级大约为M2分潮的1/5~1/4。底摩擦耗散主要发生莫桑比克海峡和马达加斯加岛南北部, 其中莫桑比克海峡M2 (S2)分潮的底摩擦耗散为1.762GW (0.460GW), 占其底部总耗散的43.74% (39.72%)。  相似文献   

2.
文章利用2014年9月南海东北部附近海域的A、B两个相距约20km的潜标数据, 分析了台风“海鸥”在南海东北部激发的近惯性振荡的垂向分布特征。结果表明, 台风过境在两站点激发了强烈的近惯性振荡, 其能量由海表向海洋内部传播; 近惯性能量在表层随着深度增加而增大, 最大值出现在次表层, 此后随着深度增加迅速衰减。但是两个观测站点的近惯性振荡垂向分布特征有较大的差别: A站点的近惯性振荡在不同深度上存在三个不同的垂向相速度, 而B站点的垂向相速度没有变化; 两站点的最大近惯性动能的大小及其所在深度不同, B站点比A站点的最大近惯性动能大15%左右。台风过后两个站点均出现由近惯性波f和半日内潮波D2非线性相互作用产生的次级波动fD2, 但其强度存在差异。台风后A站点fD2在不同深度上有不同的变化, f和D2相互作用较弱; 而B站点的fD2在整个近惯性振荡影响深度内都是增强, 其fD2和f频带的动能和流速在时空分布以及变化趋势上有较好的相关性。两站点的近惯性振荡垂向相速度以及次级波动fD2的不同可能是水体层结的差异和涡旋的影响所导致的。  相似文献   

3.
不规则波作用下的船舶撞击作用   总被引：2，自引：1，他引：2  
李玉成 《海洋学报》1980,2(3):123-136
随着波谱理论研究的发展,各种海工结构及船舶的荷载及其内力分析也日趋应用不规则波的计算方法。目前对于外海码头在波浪作用下的船舶撞击荷载还应用规则波的研究方法,对其应用不规则波分析方法的途径以及在考虑波谱作用后会有怎样的结果等问题目前还较少研究。本文试图对此问题进行初步的分析。  相似文献   

4.
以热带库里亚藻(Coolia tropicalis)为研究对象, 在不同锰浓度(0、1、5、10、50μmol·L -1)的人工海水培养15d, 利用叶绿素荧光动力学技术研究了其生长和光合作用对不同锰环境的响应。结果表明: 1)比生长速率(μ)和最大相对电子传递速率(rETRmax)与锰浓度均呈指数关系且对锰胁迫具有相同程度的响应; 2)锰浓度至少大于1μmol·L -1才能维持热带库里亚藻正常的光合作用活性, 当锰浓度低于该浓度时, 光合作用活性(Fv/Fm)在6d后开始下降, 而单位反应中心吸收光能(ABS/RC)和热能耗散(DI0/RC)升高; 两个反应中心之间的电子传递(φE0)及生长并未受影响, 表明此阶段锰缺乏只影响活性光反应中心数量并提高热耗散途径; 当锰缺乏延长至15d时, 胁迫作用显现(F0上升)并且电子传递(φE0)和生长受到抑制, 这阶段锰缺乏使光反应中心关闭且电子传递受阻; 3)锰缺乏的修复损伤比(r/k)并未降低, 表明锰缺乏并未影响热带库里亚藻的光保护能力。  相似文献   

5.
An account is given of the thermodynamical characteristics of the adsorption of uranyl complex ions on hydrous titanium oxide (HTO) in NaCl-NaHCO3 solution and in seawater. Determined are the adsorption isotherms and the adsorption density in various pH. The contribution of each component to the adsorption density, the adsorption free energy ΔGads,t, the coulostatic energy ΔGcoul,t. and the cqemisorption potential energy Gchem. t are estimated. The average free energy ΔGads enthalpy change, ΔHads, and entropy change, ΔSads, of the adsorption in this system are -7.33 kcal/mol, 6.30 kcal/mol and 45.7 cal/mol K respectively. It is hereof concluded that the complex chemisorption process is spontaneous and thermonegativc.  相似文献   

6.
黄鳍金枪鱼(Thunnus albacares)是全球经济和生态价值最重要的鱼类之一,其资源养护和管理受到各方的高度关注。本文依据年龄结构产量模型研究了印度洋黄鳍金枪鱼的资源状态,着重探讨了其生活史特征的不确定性对资源评估结果的影响。研究结果显示,1960-1985年间印度洋黄鳍金枪鱼资源量保持相对稳定,之后开始逐渐下降,相应的捕捞死亡系数也在2010年之后迅速增加,目前其种群可能存在过度捕捞(F2020/FMSY>1,SSB2020/SSBMSY<1)。印度洋黄鳍金枪鱼的资源评估结果对自然死亡系数(M)和亲体-补充量关系陡度参数(h)的改变较为敏感。当h增大时,SSBMSY和初始SSB(即SSB0)的变化较大,分别减少了约25.53万t和34.04万t;F2020/FMSY减小了1.15。当M增大时,F2020/FMSY、SSBMSY...  相似文献   

7.
海洋绿藻长茎葡萄蕨藻(Caulerpa lentillifera, 又名海葡萄)因具有较高经济和生态价值而备受关注, 光照和温度变化均会改变长茎葡萄蕨藻生理代谢, 最终影响其经济价值和生态功能。文章比较研究不同生长光强下(40、80、120和160 µmol·photons·m-2·s-1)长茎葡萄蕨藻不同部位, 即直立枝和匍匐枝的生理和生化特征, 以及其对升温(+3℃、+6℃和+9℃)的响应。结果显示, 光强由40升至120µmol·photons·m-2·s-1时对长茎葡萄蕨藻相对生长率(RGR)的影响不显著, 但是光强升至160µmol·photons·m-2·s-1时可使RGR降低49%。弱光下(40µmol·photons·m-2·s-1)直立枝的叶绿素(Chl a)和类胡萝卜素(Car)含量为匍匐枝的1.52和1.49倍; 直立枝的Chl a和Car含量随生长光强升高而降低, 匍匐枝随光强升高而升高, 二者蛋白含量则均随光强升高而先升高后降低。弱光下直立枝的净光合放氧速率(Pn)和呼吸速率(Rd)分别为匍匐枝的2倍和70%, 但是二者的最大光化学效率(FV/FM)差异不显著。光强升高提高直立枝和匍匐枝的Pn和Rd, 但对二者FV/FM的影响不显著。同时, 弱光下直立枝的超氧化物歧化酶(SOD)活性比匍匐枝低20%, 二者过氧化氢酶(CAT)活性差异不显著; 光强升高提高直立枝和匍匐枝的SOD活性, 降低CAT活性。研究还发现, 直立枝和匍匐枝的Pn随温度升高而降低, 但前者的降低程度即光合速率随升温的变化率随光强升高而降低, 后者的则随光强升高而升高, 可见温度升高在弱光下对长茎葡萄蕨藻直立枝的负面影响更大, 在强光下则对匍匐枝的负面影响更大。  相似文献   

8.
Pore water chemistry (total dissolved CO2, NH4, NO3, NO2, PO4, Si(OH)4, Ca, Mg, Fe, Mn, SO4, H2S and F, and titration alkalinity), solid phase chemistry (Corg, Porg, CTOT, NTOT, F, SiOPAL and SII), and sediment characteristics (porosity, dry bulk density and formation factors) were determined on a centimeter-scale spacing in the upper 20–40 cm of sediments under intense upwelling areas on the Peru continental shelf. These data demonstrate that carbonate fluorapatite (CFA) is precipitating from pore waters in the upper few centimeters of a gelatinous mud with high organic carbon content (up to 20% Corg), very high porosity ( > 0.96 ml cm−3) and very low dry bulk density (< 0.1 g cm−3). Dissolved phosphate concentrations at the sediment-water interface range from 20 to 100 μM, orders of magnitude higher than bottom-water concentrations, and much higher than predicted from regeneration of organic matter. The mechanism of this interfacial phosphate release is unclear, but is apparently uncoupled from carbon and nitrogen metabolism and thus may be linked either to dissolution of fish debris or to the presence of a microbial mat in surficial sediments. Fluoride is incorporated into CFA by diffusion from the overlying seawater, and carbonate ions are provided from pore-water alkalinity. Magnesium concentrations in this reaction zone are not significantly different from those of seawater, suggesting that magnesium depletion is not a necessary prerequisite for CFA precipitation.

The environment of precipitation is interface-linked rather than driven by organic diagenesis of phosphorus deeper in the sediment. Most of the cores display a wide range of diagenetic characteristics below the immediate interfacial region, but almost all show the precipitation signature near the interface. This interface-linked early diagenetic porewater environment for the precipitation of CFA explains many of the geochemical characteristics of phosphorites and provides a “testable” model to compare the modern phosphogenic analog with ancient phosphorite deposits. Two of the cores display very high solid phase phosphorus and fluoride contents reflecting the presence of apparently modern pelletal apatites.  相似文献   


9.
渤海、黄海、东海M2潮汐潮流的三维数值模拟   总被引：23，自引：2，他引：21  
利用建立的一种新的半隐半显三维数值格式,将渤海、黄海、东海作为一个整体,采用球面坐标系下的三维潮波方程组,考虑了引潮力的作用,数值模拟了渤海、黄海、东海的M2分潮的潮汐与潮流,结果较好地体现了渤海、黄海、东海M2分潮的特征.通过比较65个验潮站的实测值与计算值,所得计算结果的振幅差平均为6.4cm,相角差为6.1°,计算与实测符合良好.本文给出的问潮图与Fang于1986年给出的实测占数值综合结果基本一致.对选取的47个测流站,比较了各层潮流调和常数Ucosζ、Usinζ、Vcosη、Vsinη的计算值与实测值的偏差,偏差绝对值的平均在2.6～4.9cm/s之间.并比较分析了潮流的垂直结构,所得结果与实测符合较好.首次揭示出回流点的水平位置不随深度变化这一特性.最后给出了M2分潮的潮能消耗.  相似文献   

10.
CO2 fixation pathway of Caminibacter profundus, a chemolithoautotrophic -Proteobacteria from deep-sea hydrothermal vent, was determined and characterized by genetic and enzymatic analyses. Gene expression of key enzymes for CO2 fixation in response to salinity, pH and O2 in Medium 829 were also investigated. The results demonstrate that C. profundus contained aclB, porA and oorA, the genes encoding key enzymes of reductive tricarboxylic acid (rTCA) cycle. However, genes fragments of cbbL and cbbM encoding key enzyme of Calvin cycle were not recovered. Key enzymatic activities of ATP citrate lyase (ACL), pyruvate: ferredoxin oxidoreductase (POR) and 2-oxoglutarate: ferredoxin oxidoreductase (OOR) were also present in C. profundus. The combination of genetic and enzymatic analyses confirm that C. profundus adopted rTCA cycle for carbon assimilation. The results of aclB and oorA relative expressions of C. profundus demonstrate that the ranges of environmental factors for high genes expression were sea salt 3.0%-5.0% (optimum 3.0%), pH 5.0-6.5(optimum pH 6.5), anaerobic to microaerobic conditions (optimum 1.0% O2 ). Gene expression patterns under different conditions show similar patterns with bacterial growth, revealing that key rTCA cycle genes provided molecular basis for bacterial growth and propagation. Our results suggest that C. profundus could regulate key genes of rTCA cycle for carbon assimilation and energy metabolism in response to environmental fluctuations in hydrothermal vent.  相似文献   

11.
对Na4P2O7加入不同灰化助剂经不同温度(200～550℃)灼烧后磷的回收率进行了研究.所研究的灰化助剂除文献中已深入研究过的MgSO4和Mg(NO3)2外,还对MgCl2等10余种盐试剂进行了实验.结果表明,除Mg(NO3)2外,MgCl2,MgAc2,CaCl2,Ca(NO3)2等均能使Na4P2O7灰化后的磷完全回收(灼烧温度不低于450℃),而加入MgSO4在任何灼烧温度下磷的回收率均低于80%,效果不佳.因此,在利用目前已被广泛应用的由Solrzno和sharp所提出的方法去分析海水中颗粒磷和总磷或有机体中的磷时,应当用MgCl2(或MgAc2)作为灰化助剂来取代MgSO4.  相似文献   

12.
表层海水二氧化碳分压是评估海洋碳源汇强度的关键参数，但其实测数据较少、时空分布极不均匀，导致二氧化碳交换通量的估算有很大的不确定性，海洋源汇特征就不能确切获取。为了解决这个难题，在收集的表层大洋二氧化碳地图(Surface Ocean CO2 Atlas，SOCAT)实测数据集基础上，运用广义回归神经网络建立二氧化碳分压与经纬度、时间、温度、盐度和叶绿素浓度间的非线性关系，构建了1998?2018年间全球1°×1°经纬度的表层海水二氧化碳分压格点数据，其标准误差为16.93 μatm，平均相对误差为2.97%，优于现有研究中的前反馈神经网络、自组织映射神经网络和机器学习算法等方法。根据构建的数据所绘制的全球表层海水二氧化碳分压的分布与现有研究有较好的一致性。  相似文献   

13.
Abstract. A seasonal sampling program of five stations off the Island of Rhodes (SE Aegean Sea) was carried out in 1983–1984. Temperature, salinity, Secchi disk transparency, P-PO4, N-NO3, N-NO2, N-NH3, Si-SiO2, and chl a were measured and phytoplankton species recorded. Cell concentrations and chl a varied seasonally. with the highest values in summer (l.2 times 104 -1--1 total mean cells; 0.13 mgam-3 total mean chl a ) and the lowest in winter (2.3 times 103, 1--1 total mean cells; 0.06 mg.m-- total mean chl a ). A variation in cell abundance among stations was also noted. Quantitative relationships among the recorded taxa showed that diatoms and dinoflagellates were richer in species composition (88 and 58 total species, respectively) than coccolithophores (8 species) and other flagellates (8 species). Comparison of phytoplankton samples from different depths and stations by cluster analysis showed an irregularity or discontinuity in species associations. The SE Aegean Sea was characterized as oligotrophic on the basis of the estimated nutrient and phytoplankton concentration levels.  相似文献   

14.
In the framework of the VECTOR DIVCOST Project, a 2-year investigation was started in 2006, with the aim of testing the sensibility of microbial parameters to environmental changes and of assessing whether they can provide information about functional changes in the carbon cycle. The investigation was performed in the surface waters of two small brackish ponds (Ganzirri and Faro), located in the Cape Peloro transitional area (Sicily, Italy). The seasonal changes in both the microbial compartment [bacterioplankton, vibrios, exoenzymatic hydrolysis of proteins and polysaccharides, bacterial secondary production (HBP) and community respiration] and the trophic state of suspended matter [total suspended matter (TSM), particulate organic carbon (POC), particulate organic nitrogen (PON), C/N] were analysed in relation to the hydrological characteristics [temperature, salinity, oxygen, fluorescence, NH4, NO2, NO3, PO4]. Despite marked differences in the nutritional input and the diversification in both carbon budget and trophic level, the two ponds show similar trends in many of the investigated factors, hardly influenced by seasonal variations. Temporally coupled trends were observed for some parameters (enzyme activities, vibrios abundances, respiratory activity), whereas others (POC, PON, heterotrophic bacterial production, bacterioplankton) showed a seasonal shift between the two lakes. The different behaviour found for the some biotic parameters suggests that their response to environmental conditions may be modulated differently between the two lakes, which, despite their spatial proximity and reciprocal connection, do not always show contemporaneous functional processes.  相似文献   

15.
利用海南中东部近海海域高频地波雷达观测得到的2019年4月—2020年3月表层海流资料进行潮流调和分析和余流分析。结果表明: 海南中东部近海海域以不规则半日潮流为主, 半日分潮M2和S2以往复流为主, 全日分潮O1、K1以顺时针旋转流为主, M2、S2、O1、K1分潮最大潮流流速的比为1 : 0.51 : 0.60 : 0.65, M2为最主要分潮。最大可能潮流流速分布从西南方向向东北方向逐步增大, 最大值为35cm·s-1。余流受东亚季风影响较大, 季节变化特征显著, 呈夏季形态(6月—8月)、冬季形态(9月—次年2月)和过渡形态(3月—5月)。夏季形态流向东北, 平均流速29cm·s-1; 冬季形态持续时间最长, 流向西南, 平均流速36cm·s-1, 大于夏季形态; 过渡形态为冬季形态向夏季形态的转变期, 流向分布较复杂, 平均流速13cm·s-1, 明显小于夏季和冬季形态。从全年来看, 西南向流动的时间最长、流速最大, 海南中东部表层海水物质输运自东北向西南。  相似文献   

16.
北部湾东北部表层沉积物主微量元素空间分布特征   总被引：1，自引：0，他引：1  
A multi-index analysis including grain size, major and trace elements is performed on the surface sediments from the northeastern Beibu Gulf to trace the sources of the sediments and to understand the controlling factors for elements distribution. The mean grain size exhibits a wide variation ranging from 0.09Φ to 8.05Φ with an average value of 5.33Φ. The average contents of major elements descend in an order of c(SiO_2)c(Al_2O_3)c(Fe_2O_3)c(CaO)c(MgO)c(K_2O)c(Na_2O)c(TiO_2)c(P_2O_5)c(MnO), while those of trace elements exhibit a descending order of c(Sr)c(Rb)c(V)c(Zn)c(Cr)c(Pb)c(Ni)c(Cu)c(As). On the basis of elementary distribution characteristics and statistical analyses, the study area is divided into the four zones: Zone I is located in the northeastern coastal area of the gulf, which receives large amount of fluvial materials from local rivers in Guangxi and Guangdong, China, and the Qiongzhou Strait; Zone Ⅱ is located in the center of the study area, where surface sediments exhibits a multiple source; Zone Ⅲ is located in the Qiongzhou Strait, where surface sediments are dominated by materials from the Zhujiang River and Hainan; Zone IV is located in the southwest of the study area, where surface sediments are mainly originated from the Red River and Hainan. The statistical analyses of sediment geochemical characteristics reveal that the grain size, which is mainly influenced by hydrodynamics and mineral composition of terrigenous materials, is the leading factor controlling the elementary distribution.Meanwhile, impacts from anthropogenic activities and marine biogenic process will also be taken into consideration.  相似文献   

17.
measurements by a circular array consisting of 18 wave gauges in a large wave tank, directional spectra of wind-generated waves in deep water are systematically determined by using maximum likelihood method The investigations reveal that the angular spreading of the wave energy is consistent with cos2s(θ/2) proposed by Longuet-Higgins et al.(1963, Ocean Wave Spectra, 111-136), if the bimodal distributions of wave energy are not taken into account. Bimodality occurring on higher frequency than peak frequency is too rare to affect our whole resalts. Surprisingly, a much broader directional spreading than that of the field, which is interpreted by the strongly nonlinear energy transfer because of the very young waves in laboratory, is found. The parameter s depends on frequency in the same way as observed by Mitsuyasu et al.(1975, Journal of Physical Oceanography, 5, 750-760) and Hasselmann et al.(1980, Journal of Physical Oceanography, 10, 1264-1280) in the field, and the relationship between the four nondimensional parameters sm, fo, b1 and b2, determining the directional width, and ū10 (corresponding to the inverse of wave age) are given respectively. The observed distributions are found to agree well with the suggestion of Donelan et al.(1985, Philosophical Transaction of Royal Society of London, A315, 509-562) when applied to field waves.  相似文献   

18.
In this study, to meet the need for accurate tidal prediction, the accuracy of global ocean tide models was assessed in the South China Sea (0°–26°N, 99°–121°E). Seven tide models, namely, DTU10, EOT11a, FES2014, GOT4.8, HAMTIDE12, OSU12 and TPXO8, were considered. The accuracy of eight major tidal constituents (i.e., Q1, O1, P1, K1, N2, M2, S2 and K2) were assessed for the shallow water and coastal areas based on the tidal constants derived from multi-mission satellite altimetry (TOPEX and Jason series) and tide gauge observations. The root mean square values of each constituent between satellite-derived tidal constants and tide models were found in the range of 0.72–1.90 cm in the deep ocean (depth>200 m) and 1.18–5.63 cm in shallow water area (depth<200 m). Large inter-model discrepancies were noted in the Strait of Malacca and the Taiwan Strait, which could be attributable to the complicated hydrodynamic systems and the paucity of high-quality satellite altimetry data. In coastal regions, an accuracy performance was investigated using tidal results from 37 tide gauge stations. The root sum square values were in the range of 9.35–19.11 cm, with the FES2014 model exhibiting slightly superior performance.  相似文献   

19.
The carbonate system in the central South China Sea   总被引：1，自引：0，他引：1  
The Clements of the carbonate system (HCO3- , CO32-, CO2, ·CO2 and Pco2) in the central South China Sea have been calculated by determining the pH values and total alkalinity of the seawater samples collected at 42 stations, combining simultaneously with the data of the temperatures, salinity and depths. The distributions of their characteristics have been briefly described and discussed. The saturation degrees (Ω) of calcite and aragonite in the studied area have also been evaluated. The ΩcaIc- and Ωarag. in the surface waters are about 5.8 and 3.9, respectively. The saturation depth is about 2200m for calcite and 1200m for aragonite. The lysocline in the studied area probably lies between 3000 m and 4000 m where the saturation degree of calcite is approximately 0.78.  相似文献   

20.
垂直分辨率对长江口海域M2分潮模拟的影响   总被引：1，自引：0，他引：1  
基于EFDC(Environmental Fluid Dynamics Code)模式建立了长江口及其邻近海域的三维水动力学模型, 研究模型的垂直分辨率对该海域M2分潮模拟的影响。结果表明:垂直分辨率的变化对M2分潮传播方向的模拟结果影响较小, 但其可通过底摩擦和湍流耗散两个计算过程来影响潮能通量的模拟结果, 最终对长江口和杭州湾内的M2分潮振幅产生显著的影响。最底层厚度较大时, 上层自由水体的高流速特征在最底层过于明显, 进而导致计算的底摩擦应力偏高, 此时提高底层的垂直分辨率会降低底摩擦对能量的耗散。另一方面, 垂直湍流混合作用会随垂直分辨率的增加而增强, 所以垂直分辨率增加到一定程度后, 上层自由水体的高流速会经由增强的湍流混合而更多的传入底层, 使计算的底摩擦应力随垂直分辨率的提高而有重新增加的趋势, 进而又增强底摩擦对潮能的耗散。  相似文献   

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