Alkaline phosphatase activity and its relationship to inorganic phosphorus in the transition zone of the North-western African upwelling system     

Marta Sebastin  Javier Arístegui  María F. Montero  Jose Escanez  F. Xavier Niell 《Progress in Oceanography》2004,62(2-4):131

The enzymatic activity of alkaline phosphatase (APA) was studied in the transition zone between the African upwelling system and the open ocean waters of the Canary Islands region. This region is recurrently dominated by the presence of upwelling filaments that may transport nutrient-enriched waters out into the open ocean before nutrients become exhausted by plankton. Turnover rates by APA were generally low in the whole region, but detectable in all the measurements carried out. On average, turnover rates were higher in the upwelling stations, and APA in those waters seemed to be mainly generated by heterotrophic bacteria to supply easily assimilable organic C. APA outside the upwelling area showed an inverse hyperbolic relationship with increasing phosphate, suggesting the presence of both constitutive and Pi-inducible APA. In these offshore waters, a threshold of 0.1 μM of phosphate could be defined for the regulatory function of Pi on APA. Thus, APA in nutrient-poor waters seemed to be induced to compensate for Pi-deficiency. Turnover rates in the filaments showed basal (probably constitutive) levels, whereas they increased in the surrounding waters, where phosphate concentration presumably did not satisfy plankton P-demands. The fertilising effect of the filaments and associated cyclonic eddies extended to at least 175 km offshore, where basal alkaline phosphatase activities were still found. The magnitude of this effect depends probably on the intensity of upwelling events and the degree of recirculation of filament water back to the coastal jet.  相似文献   

Management of the commons for biodiversity: lessons from the North Pacific   总被引：1，自引：0，他引：1  

Jerry McBeath   《Marine Policy》2004,28(6):580

The North Pacific has the world's largest groundfish fisheries, with a value in excess of $1 billion annually. The North Pacific also is home to the largest population of Steller sea lions (SSL), an ancient species that is now endangered. Decline of the western stock of SSL in the 1970–1990s coincided with the US nationalization and exponential growth in the Gulf of Alaska and Bering Sea/Aleutian Islands groundfish fishery.The article treats five aspects of the competition between the fishery and protection of the endangered species. First, we analyze competition of interests in the use, management, and preservation of the North Pacific commons, including offshore and near-shore fisheries, environmental organizations, governments (federal, state, and local), and the scientific community. Second, the article compares and contrasts provisions of the National Environmental Policy Act, the Marine Mammal Protection Act, the Endangered Species Act, and the Magnuson–Stevens Act (as amended in 1996 by the Sustainable Fisheries Act).Third, we examine the regulatory environment with a focus on the National Marine Fisheries Service (NMFS) and its relationship to the North Pacific Fishery Management Council. We illustrate how NMFS establishes fishery management plans and the methods, such as crafting biological opinions and environmental-impact-statements, it uses to resolve conflicts. Fourth, we investigate how the dual pressures on the agency—to increase fisheries production for the benefit of the industry and to preserve endangered marine species—have affected its culture (behavioral norms and operational codes). Then, the article explains agency changes in terms of crises, competition among affected interests, and development of new scientific knowledge.The article concludes by drawing lessons from the SSL controversy in the North Pacific which may pertain to national and global biodiversity conflicts. These concern the role of law in biodiversity protection, the role of science, and agency capacity for change.  相似文献   

人造海洋涌升流和海洋渔场   总被引：1，自引：0，他引：1  

李冠成  王秉坤  李明  范喆  王莉  卢佃清 《海洋技术学报》2003,22(2):74-78

针对渔业资源日趋减少和鱼产品需求不断增加的矛盾，探讨了建造海底山脉、人工制造海洋涌升流、从而人工制造优良海洋渔场的可行性，分析了我国建造海底山脉的水深、海底和海流条件。介绍了建造海底山脉的建筑方法和国际上建造海底山脉的最新动态。论述了我国在200n mile以内建造海底山脉的有利条件。  相似文献   

分形分析方法在海冰趋势预测中的应用   总被引：1，自引：0，他引：1  

高振会  杨建强  费立淑 《海洋通报》2003,22(4):66-69

根据渤海北部1966——2001海冰冰级年际变化的实际资料，利用R／S分析的原理和方法计算了H指数，建立了R(i)/S(i)与i的关系式，对渤海北部海冰趋势进行了预测分析。结果表明，利用分形分析方法进行海冰趋势预测不仅方法简便，而且结论具有客观性，可以将其作为海冰趋势预测中较为有效的一种方法。  相似文献   

Seasonal and Spatial Variations of Iceberg Drift off Dronning Maud Land, Antarctica, Detected by Satellite Scatterometers   总被引：1，自引：0，他引：1  

Shigeru Aoki 《Journal of Oceanography》2003,59(5):629-635

Seasonal and spatial variations of iceberg drift were studied using continuous satellite scatterometer images off Dronning Maud Land, East Antarctica. Generally, iceberg drift speed showed a westward increase to the Greenwich Meridian. Seasonal variations of the drift speed were high in autumn—early winter and low in spring, and their magnitudes also increased westward. Seasonal variations of the drift speed were significantly correlated with variations of sea levels at Syowa and Mawson Stations, and hence qualitatively consistent with geostrophic current variations. Thus, the scatterometer data are demonstrated to be useful in monitoring iceberg trajectory and oceanic current variations. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Sea surface height anomaly and geostrophic circulation variations in the South China Sea from TOPEX/POSEIDON altimetry     

Liu Kexiu  Ma Jirui  Xu Jianping  Han Guijun  Fan Zhenhua 《海洋学报(英文版)》2002,21(3):345-354

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   

北太平洋亚热带环流区表层水中226Ra和228Ra的分布与变化     

李艳平  陈敏  黄奕普  蔡毅华 《台湾海峡》2004,23(3):261-267

对1999年9～10月采自北太平洋亚热带环流区的19份表层海水样品的Ra同位素分析表明。研究海域表层水中的^226Ra、^228Ra放射性比度分别介于0．67～0．92、0．08～0．30Bq／m^3之间，平均值分别为0．74、0．11Bq/m^3．^226Ra/^228Ra)A．R．活度比的变化范围为0．11～0．44，平均值为0．19．上述数值明显低于近岸海域水体的相应值，表现为典型的开阔大洋水的特征．从空间分布的特征看，研究海域Ra同位素含量与^226Ra/^228Ra)A.R.值均呈均匀分布态势．将本研究结果与历史数据进行对比后发现，本研究获得的^226Ra、^228Ra放射性比度比20世纪60～80年代得到的数据来得低，可能与水体层化作用加强导致的Ra补充量的减少以及生物生产力升高导致的Ra迁出量的增加有关．北太平洋亚热带环流区表层水中Ra同位素的时间变化与文献报道的该海域叶绿素a、硅酸盐、磷酸盐含量与初级生产力的历史变化趋势相吻合．  相似文献   

海上浮动软管的三维静态分析     

孟浩龙  张海明等 《海洋工程》2003,21(1):109-112

提出了海上浮动软管的三维静态分析模型。在四级海情下，对输送柴油的软管求得了解析解，得出了软管在侧向和垂直方向的偏移及其所受的拉力，认为此时的软管是不安全的。  相似文献   

青岛海陆风三维结构的数值模拟   总被引：4，自引：1，他引：4  

常志清  吴增茂  高山红 《中国海洋大学学报(自然科学版)》2002,32(6):877-883

本文采用 1个陡地形影响修正的三维中尺度流体静力的气象学模式 ,对青岛地区海陆风的日变化规律和三维结构进行了较细致的分析。结果显示 ,青岛有多支海陆风存在 ,且每支海陆风出现的时间、强度和向内陆伸展的距离有很大的不同。这其中沿岸山地的机械和热力作用扮演着重要的角色。在观测站 ,模拟结果和实测资料等方面有较好的一致性。  相似文献   

珊瑚礁岩心声速垂向跃变及其指相意义     

李赶先  卢博 《台湾海峡》2001,20(3):308-313

本文在南沙群岛永署礁南永1井珊瑚礁岩心声速测量的基础上，研究了珊瑚礁岩心声速的垂向跃变特征和相应地层沉积相变及地层侵蚀间断面的关系，分析了珊瑚礁岩心相变造成其声速跃变的原因，阐明了海平面升降形式珊瑚礁地层侵蚀间断面和产生相变的具体过程, 明了珊瑚礁岩心声速垂向跃变与相应地层古气候和海平面变化的关系，该项研究在岛礁工程建设和礁灰岩区石油勘探声学测井以及西太平洋边缘海古海洋学研究学方面具有重要的实用价值和理论意义。  相似文献