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81.
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83.
冲绳海槽北部表层沉积物中的钙质超微化石及其环境特征 总被引:4,自引:2,他引:4
为探讨冲绳海槽表层沉积物中钙质超微化石的分布规律及其影响因素 ,对海槽北部槽坡区 ( 2 9°5 8.33′— 31°31 .2 3′N ,1 2 7°39.5 5′— 1 2 8°5 9.61′E) 34个表层样品进行了分析和研究。共发现 35种钙质超微化石 ,其中优势种为Gephyrocapsaoceanica、Emilianiahuxleyi和Florisphaeraprofun da ;G .oceanica、E .huxleyi等的百分含量变化和特征属种U .tenuis的出现 ,表明该区钙质超微化石组合面貌与东海外陆架相似 ,和东海及南海都属于北太平洋中央水团组合。G .oceanica的含量与海水营养盐存在一定的关系 ,但两者之间并不存在明显的正相关性 ;暖水分子U .irregularis、U .sibogae和O .fragilis的较高含量和冷水分子G .caribbeanica和Calcidiscusleptoporus的较低含量 ,进一步反映该区钙质超微化石的分布受到黑潮及对马暖流的影响 ,其中温度、盐度和表层海水结构性质 ,如海水透明度等因素可能为主要控制因素。 相似文献
84.
The sea surface height anomaly (SSHA) and geostrophic circulation in the South ChinaSea (SCS) are studied using TOPEX/POSE1DON (T/P) altimetry data. The SSHA, which is obtained after tidal correction based on the tidal results from T/P data, is predominated by seasonal alternating monsoons. The results reveal that the SSHA in the central part of the SCS is positive in spring and summer, but negative in autumn and winter. It is also found that the SSHA in the SCS can be approached with the sum of tidal constituents SA and SSA. The geostrophic circulations in the SCS are calculated according to sea surface dynamic topography, which is the sum of SSHA and mean sea surface height. It is suggested that the circulation in the upper layer of the SCS is generally cyclonic and notably western intensified during autumn and winter, while the western intensification is weak during spring and summer. It is also indicated that the Kuroshio intrudes into the northeastern SCS throuth the Luzon Strait in winter. But ther 相似文献
85.
Suction dredging for cockles removes large cockles from tidal flats and may also cause mortality of non-target fauna and make the habitat less suitable for some species. This study examines whether suction dredging for cockles on tidal flats of the Dutch Wadden Sea had affected densities of non-target fauna, directly after fishing and one year later. Densities of non-target fauna in two randomly chosen undredged locations were compared to densities at the surrounding heavily commercially dredged area. A significant negative effect of cockle dredging on densities of 0-group Macoma balthica was observed and this effect persisted one year after dredging. The dredged area appeared to be less suitable for settlement of mussels Mytilus edulis. No significant effects of dredging on the mudsnail Hydrobia ulvae and on 0 and 1-group C. edule were found. For the mobile young Macoma balthica it seems unlikely that the effect found after one year was still due to the mortality caused by dredging and this suggests that the habitat was less suitable as a consequence of dredging. Thus, even in the highly dynamic ecosystem of the Wadden Sea, effects of bottom disturbance by cockle dredging may persist after one year. 相似文献
86.
Using meteorological data of field observation in 1990 - 2000, especially polar orbit high-resolution NOAA satellite cloud maps received from the Antarctic expedition vessel since 1997, the formation and development of the Prydz Bay cyclone are studied in this paper. Some new viewpoints are suggested such as: when surround-polar cyclone enters the Prydz Bay, it can also intensify and develop in summer; cyclone can also develop in the easterlies in this bay. These view points revise old uncom-plete view point that the Prydz Bay is a burial ground of cyclone, and also further consummate formation-development theory of surround-cyclone in the Antarctic westerlies and cyclone in the Antarctic easterlies. In this paper, the mechanism of ice-air-sea interaction in the Prydz Bay is studied, and the physical process of cyclone formation-development is explained. By use of wholly dynamic transportation method, an energy exchange case of a cyclone, which explosively developed after entering the Prydz Bay, is calcu 相似文献
87.
东海秋季典型站位沉降颗粒物通量 总被引:6,自引:0,他引:6
2002年9月在东海的长江口、中陆架区和浙江近岸上升流区三个站位放置沉积物捕获器采集沉降颗粒物。在对颗粒有机碳(POC)、颗粒有机氮(PON)和总颗粒碳(PC)元素分析基础上,采用颗粒物通量模型对沉降通量进行了研究。镜检发现细小无机颗粒物和大颗粒聚合体是三个站位沉降颗粒物的主要形式。大颗粒聚合体有住囊类、粪球聚合体、硅藻聚合体和混杂聚合体四种类型。研究结果显示,东海中陆架区和浙江近岸上升流区沉降颗粒物中POC、PON和PC的百分含量均呈现随水深增加明显降低的趋势,但在长江口,这些成分的含量低且上下均匀。长江口观测到的是大风后的一个实例,存在强烈的再悬浮,各水层颗粒物沉降通量平均(±SE)高达(319.02±65.33)g/(m2.d),尽管如此,沉降颗粒物有机态C/N值却很高(18.0±0.9),明显受陆源颗粒物的影响。POC净沉降通量在浙江近岸上升流区为961mg/(m2.d)(水深55m),在东海中陆架区为123mg/(m2.d)(水深88m),可见浙江近岸上升流区是POC向海底转移的重要区域之一,其垂直转移能力明显高于东海中陆架区。在上升流区域和中陆架区,POC的输出比率大约分别为48%—77%和15%—21%。浙江近岸上升流区和东海中陆架区底层颗粒物再悬浮比率分别为66.50%和88.52%。研究显示,浙江近岸上升流区的水体底层颗粒物受底部平流的影响比东海中陆架区相对较强。 相似文献
88.
本文提出在小偏心受压构件正截面强度计算中,取消弯曲抗压强度fcm(Rw),采用轴心抗压强度fc,这与构件的实际破坏形态相符。对小偏心受压构件正截面强度计算提出了设计建议。特别是对工程上大量应用的矩形截面对称配筋小偏压构件提示了简捷的设计方法,与以往的近似计算方法相比具有物理概念明确,精度高,方法简捷的特点。 相似文献
89.
本文测定了一次培养实验和连续培养实验中三角褐指藻胞外产物的变化及其与汞的络合性能。28天的培养过程中测得胞外产物与汞的络合容量C_L为2.6×10~(-5)mol/dm~3;表观稳定常数K′为6.1×10~(10)。该结果解释了细胞培养过程中胞外有机物的释放对汞的解毒机理及对介质中汞形态的转化。 相似文献
90.
J. Perbos P. Escudier F. Parisot G. Zaouche P. Vincent Y. Menard F. Manon G. Kunstmann D. Royer L. -L. Fu 《Marine Geodesy》2003,26(3):147-157
On 7 December 2001, Jason-1 was successfully launched by a Boeing Delta II rocket from the Vandenberg Air Force Base, California. The Jason-1 satellite will maintain the high accuracy altimeter service provided since 1992 by TOPEX/Poseidon (T/P), ensuring the continuity in observing and monitoring the Ocean Dynamics (intraseasonal to interannual changes, mean sea level, tides, etc.). Despite one-fourth the mass and power, the Jason-1 system has been designed to have basically the same performance as T/P, measuring sea surface topography at a centimetric level. This new CNES/NASA mission also provides near real-time data for sea state and ocean forecast. The first two months of the Jason-1 mission have been dedicated to the assessment of the overall system. The goals of this assessment phase were:
1. To assess the behavior of the spacecraft at the platform and payload levels (Jason-1 being the first program to call on the PROTEUS versatile multimission platform for Low and Medium Earth Orbit Missions developed in partnership between Alcatel Space and CNES);
2. To verify that platform performance requirements are met with respect to Jason-1 requirements;
3. To verify that payload instruments performance requirements evaluated at instrument level are met;
4. To assess the performance of the Jason-1 Ground System.
This article will display the main outputs of the assessment of the system. It will demonstrate that all the elements of the onboard and ground systems are within the specifications. Provision of data to the Jason-1 Science Working Team started at the end of March 2002. This is the goal of a six-month phase after closure of the initial assessment phase to derive the error budget of the system in terms of altimetry user products. 相似文献
1. To assess the behavior of the spacecraft at the platform and payload levels (Jason-1 being the first program to call on the PROTEUS versatile multimission platform for Low and Medium Earth Orbit Missions developed in partnership between Alcatel Space and CNES);
2. To verify that platform performance requirements are met with respect to Jason-1 requirements;
3. To verify that payload instruments performance requirements evaluated at instrument level are met;
4. To assess the performance of the Jason-1 Ground System.
This article will display the main outputs of the assessment of the system. It will demonstrate that all the elements of the onboard and ground systems are within the specifications. Provision of data to the Jason-1 Science Working Team started at the end of March 2002. This is the goal of a six-month phase after closure of the initial assessment phase to derive the error budget of the system in terms of altimetry user products. 相似文献