大姚、民乐-山丹地震前的中短期前兆   总被引：5，自引：2，他引：3  

张希  薛富平  王双绪 《大地测量与地球动力学》2004,24(4):57-63

利用川滇及青藏块体北缘地区上世纪80年代至2003年的跨断层流动形变观测资料，借助应变强度比时序曲线，通过丽江Ms7．0、景泰Ms5．9等震例研究，获取与2003年7月大姚Ms6．2、Ms6．1地震和10月民乐-山丹Ms6．1地震孕育有关的中短期前兆异常。分析表明：①大姚、民乐-山丹地震前1年内异常场地数远超过场地总数的1／3，相对近源区异常在发震地区占一半；②大姚Ms6．2地震前半年内，盐源-丽江地块及其邻近区域以及北东向延伸的川滇交界地区异常明显增多，相对集中。2003年7～9月大幅减弱；而鲜水河断裂、楚雄-通海断裂南段有所增强；③民乐-山丹震前十余天至数月内相对近源区及其邻近构造区域呈现异常相对分散-相对集中且局部增强-一临震前减弱的时空演变特征。震后一个月内青藏块体北缘地区仍有近1／3的场地呈现异常(海原一六盘山断裂带尤为突出)。  相似文献   

Analysis of VIV for Barrel-Shaped Mast with Covering Ice by HPD-S Method     

张营川  马骏  赵德有 《中国海洋工程》2009,23(4):763-768

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Perturbed solution of sea-air oscillator for the E1 Ni(n)o/La Ni(n)a-Southern Oscillation mechanism     

ZHOU Xianchun  LIN Yihua  WANG Hui  MO Jiaqi 《海洋学报(英文版)》2009,28(3)

A class of coupled system of the E1 Ni(n)o/La Ni(n)a-Southern Oscillation (ENSO) mechanism is studied. Using the perturbed theory, the asymptotic expansions of the solution for ENSO model are obtained and the asymptotic behavior of solution for corresponding problem is considered.  相似文献   

Denitrification in Qi''ao Island coastal zone, the Zhujiang Estuary in China   总被引：1，自引：0，他引：1  

WANG Hu  ZHOU Huaiyang  PENG Xiaotong  YANG Qunhui  QIN Chaomei  YIN Xijie  CHEN Guangqian 《海洋学报(英文版)》2009,28(1):37-46

Samples of sediments and the overlying water were collected in the Qi'ao Island coastal zone, the Zhujiang (Pearl River) Estuary (ZE). Denitrification rates, sediment oxygen demand (SOD) , and fluxes of inorganic nitrogen compounds were investigated with N2 flux method, using a self-designed continuous flow through and auto-sampling system. The results indicate that the denitrification rates varied between 222 and 908 μmol/(m2·h) with an average of 499 μmol/(m2·h). During incubation, the sediments absorbed dissolved oxygen in the overlying water with SOD ranging from 300 to 2 363 μmol/(m2·h). The denitrification rates were highly correlated with the SOD (r2 =0.77) regardless of the NO3- + NO2- concentrations in the overlying water, organ- ic carbon contents in sediments and water temperature, suggesting that the SOD was probably the main environ-mental factor controlling the denitrification in the Qi'ao Island coastal zone. There was a net flux of NO3- + NO2-into the sediments from the overlying water. The NH4+ flux from sediments into water as the result of mineraliza-tion was between 12. 3 and 210. 3 μmol/(m2·h) ,which seems limited by both organic carbon content in sedi-ment and dissolved oxygen concentration in the overlying water.  相似文献   

Application of an ecosystem model for the environmental assessment of the reclamation and mitigation plans for seagrass beds in Atsumi Bay   总被引：1，自引：0，他引：1  

Akio Sohma  Yasuyuki Sekiguchi  Kisaburo Nakata 《Estuarine, Coastal and Shelf Science》2009

An ecosystem model was used to evaluate the effects of reclaiming seagrass beds and creating artificial shallows with seagrass beds to mitigate the effects of the reclamation. The applied model can simulate the pelagic and benthic ecosystems including seagrass beds and tidal flats. The objectives of this study were (a) to investigate the likelihood of cultivating and maintaining seagrass beds in artificial shallows (Part 1), and (b) to understand the effects of the reclamation of seagrass beds and the creation of artificial shallows on the water quality in the estuary (Part 2). In Part 1, first, the nutrient turnover rates due to both biochemical and physical processes in the natural seagrass beds where reclamation is proposed were analyzed. Biological processes rather than physical processes were the most significant driving forces of nutrient cycles in seagrass beds. Second, the effects of filter feeding benthic fauna (suspension feeders) in the seagrass beds were analyzed. The scenario with suspension feeders resulted in higher transparency of the water column (8.7% decrease in the light attenuation coefficient) and an increase in nutrient supply (24.9% increase in NH₄-N in the water column) contributing to the high specific growth rate of seagrass. Third, the specific growth rate of seagrass on the proposed artificial shallows was measured. The value on the artificial shallows set at a depth of datum line minus 0.8 m (D.L. − 0.8 m) was approximately the same as that of the natural seagrass beds. In Part 2, first, water quality in the estuary was compared among the scenarios with/without natural seagrass beds and artificial shallows. Then, the defined values of the water purification capability of (a) artificial shallows with/without seagrass beds, and (b) natural seagrass beds per unit area were evaluated. The reclamation of the natural seagrass beds resulted in a decrease of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a loss in the purification rate). In contrast, the creation of artificial shallows resulted in an increase of the removal of phytoplankton and detritus from the pelagic system (i.e. resulted in a gain in the purification rate). Based on an annual average, approximately twice as much phytoplankton was removed from the artificial shallows at the depth D.L. − 0.8 m, than at the depth, D.L. − 1.5 m, and the artificial shallows with seagrass beds removed pelagic DIN and DIP at a rate 120% higher than that without seagrass beds.  相似文献   

Resolving physically and biologically driven suspended particulate matter dynamics in a tidal basin with a distribution-based model   总被引：1，自引：0，他引：1  

Joeran Maerz  Kai Wirtz 《Estuarine, Coastal and Shelf Science》2009

Understanding suspended particulate matter (SPM) dynamics in coastal waters is crucial to assess changes in coastal sediment budgets and biogeochemical fluxes. SPM dynamics are subject to various physical and biological factors and processes such as, e.g. tidal currents and aggregation which can be enhanced by extracellular polymeric substances (EPS) that are produced by algae and bacteria. It is still unclear how the different factors and processes interact and together determine SPM dynamics. To unravel the interacting processes and factors, we propose a new distribution-based modeling approach. Based on the derivation of explicit equations for size distribution characteristics of SPM such as the average radius, we derived a model of reduced complexity characterized by low initialization and parameterization effort as well as low computational cost. The proposed 0D model includes the processes of aggregation and fragmentation due to shear, aggregation due to differential settling, deposition, resuspension and tidal exchange, and describes the evolution of the SPM concentration in the water column linked by the settling velocity to the change of the mass average radius of the aggregate distribution. A systematic parameter variation for critical bottom shear stress of erosion, the size of resuspended aggregates, the fractal dimension, the collision efficiency, and the aggregate strength has been performed and compared to observations in the back-barrier basin of Spiekeroog Island in the German Wadden Sea. This analysis confirms the hypothesis that in winter biological influences on SPM dynamics are smaller compared to summer. This is mainly reflected by a significant shift in the various parameters. We hence conclude that biological control mechanisms have a much more quantitative relevance for SPM dynamics than currently represented by state-of-the-art SPM transport models.  相似文献   

Observations of the North Equatorial Current,Mindanao Current,and Kuroshio current system during the 2006/07 El Niño and 2007/08 La Niña   总被引：1，自引：0，他引：1  

Yuji Kashino  Norievill España  Fadli Syamsudin  Kelvin J. Richards  Tommy Jensen  Pierre Dutrieux  Akio Ishida 《Journal of Oceanography》2009,65(3):325-333

Two onboard observation campaigns were carried out in the western boundary region of the Philippine Sea in December 2006 and January 2008 during the 2006/07 El Niño and the 2007/08 La Niña to observe the North Equatorial Current (NEC), Mindanao Current (MC), and Kuroshio current system. The NEC and MC measured in late 2006 under El Niño conditions were stronger than those measured during early 2008 under La Niña conditions. The opposite was true for the current speed of the Kuroshio, which was stronger in early 2008 than in late 2006. The increase in dynamic height around 8°N, 130°E from December 2006 to January 2008 resulted in a weakening of the NEC and MC. Local wind variability in this region did not appear to contribute to changes in the current system.  相似文献   

钱塘江强潮河段江道缩窄治理研究   总被引：1，自引：0，他引：1  

陈来华  潘存鸿 《海洋工程》2008,26(2):96-102

对钱塘江强潮河段江道缩窄治理进行研究。首先,回顾治理方案的比选,江道全线缩窄时河轴线线路和河道宽度的确定原则,以及不同河段的指数放宽率。然后,介绍了在涌潮汹涌、滩涂淤坍变化剧烈的强潮河段,实施筑堤所采取的工程措施的步序与要点。最后,分析论证了大规模江道缩窄治理后河床、潮汐、洪水位及涌潮高度等特征值的变化。可供进一步深入理论研究和工程施工参考运用。  相似文献   

投喂四种饵料对曼氏无针乌贼(Sepiella maindroni)繁殖性能的影响          下载免费PDF全文

樊晓旭  王春琳  邵银文  王津伟  宋超霞  蒋霞敏 《海洋与湖沼》2008,39(6):634-642

以双齿围沙蚕、泥鳅、黄鲫、福寿螺4种不同饵料强化培育胴长(6.50±0.20)cm的曼氏无针乌贼,用曼氏无针乌贼肝脏和卵巢的氨基酸与脂肪酸变化、亲体产卵量、卵径、卵子孵化率及其幼体成活率等指标来评价4种饵料对其繁殖性能的影响.结果表明,黄鲫组曼氏无针乌贼肝脏与卵巢中∑EAA、∑SEAA、∑EAA+SEAA、∑NEAA、∑AA含量在第一次卵巢成熟与第二次卵巢成熟时均显著高于其它投喂组(P＜0.05).黄鲫组乌贼肝脏DHA/EPA在第一次卵巢成熟时显著高于其它投喂组,在第二次卵巢成熟时DHA、DHA/EPA、∑n3PUFA、∑n6PUFA、∑n3/n6PUFA都显著高于其它投喂组(P＜0.05);该组乌贼第一次卵巢成熟卵巢DHA、∑n3PUFA、∑n6PUFA、∑n3/n6PUFA及在第二次卵巢成熟时卵巢DHA、DHA/EPA、∑n3PUFA、∑n3/n6PUFA均显著高于其它投喂组(P＜0.05),该组第二次卵巢成熟时∑n6PUFA百分含量与沙蚕组无显著差异(P＞0.05).产卵量多少顺序为黄鲫组＞沙蚕组＞泥鳅组＞福寿螺组(P＜0.05);孵化率高低顺序为黄鲫组＞福寿螺组＞泥鳅组＞沙蚕组(P＜0.05);所产卵子平均直径大小顺序为黄鲫组＞泥鳅组＞沙蚕组＞福寿螺组(P＜0.05);幼体成活率高低顺序为黄鲫组＞泥鳅组＞沙蚕组、福寿螺组(P＜0.05).各指标吻合程度高.  相似文献   

Estimates of global M_2 internal tide energy fluxes using TOPEX/POSEIDON altimeter data     

张艳伟  梁鑫峰  田纪伟  杨丽芬 《中国海洋湖沼学报》2009,27(1)

TOPEX/POSEIDON altimeter data from October 1992 to June 2002 are used to calculate the global barotropic M2 tidal currents using long-term tidal harmonic analysis. The tides calculated agree well with ADCP data obtained from the South China Sea (SCS). The maximum tide velocities along the semi-major axis and semi-minor axis can be computed from the tidal ellipse. The global distribution of M2 internal tide vertical energy flux from the sea bottom is calculated based on a linear internal wave generation model. The global vertical energy flux of M2 internal tide is 0.96 TW, with 0.36 TW in the Pacific, 0.31 TW in the Atlantic and 0.29 TW in the Indian Ocean, obtained in this study. The total horizontal energy flux of M2 internal tide radiating into the open ocean from the lateral boundaries is 0.13 TW, with 0.06 TW in the Pacific, 0.04TW in the Atlantic, and 0.03 TW in the Indian Ocean. The result shows that the principal lunar semi-diurnal tide M2 provides enough energy to maintain the large-scale thermohaline circulation of the ocean.  相似文献