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51.
董胜 《中国海洋大学学报(自然科学版)》1997,(2)
针对海上矿石运输,介绍了一种完成定量任务并能使投资费用最少为目标的最优船队组建方法,同时对易变参数进行了灵敏度分析,使决策更加科学化 相似文献
52.
In this study, the impact of oceanic processes on the sensitivity of transient climate change is investigated using two sets of coupled experiments with and without tidal forcing, which are termed Exp_Tide and Exp_Control,respectively. After introducing tidal forcing, the transient climate response(TCR) decreases from 2.32 K to 1.90 K,and the surface air temperature warming at high latitudes decreases by 29%. Large ocean heat uptake efficiency and heat storage can explain the low TCR in Exp_Tide. Approximately 21% more heat is stored in the ocean in Exp_Tide(1.10×10~(24) J) than in Exp_Control(0.91×10~(24) J). Most of the large ocean warming occurs in the upper 1 000 m between 60°S and 60°N, primarily in the Atlantic and Southern Oceans. This ocean warming is closely related to the Atlantic Meridional Overturning Circulation(AMOC). The initial transport at mid-and high latitudes and the decline in the AMOC observed in Exp_Tide are both larger than those observed in Exp_Control. The spatial structures of AMOC are also different with and without tidal forcing in present experiments. The AMOC in Exp_Tide has a large northward extension. We also investigated the relationship between AMOC and TCR suggested by previous studies using the present experiments. 相似文献
53.
Shallow-Water Gasohydrothermal Vents of Ushishir Volcano and the Ecosystem of Kraternaya Bight (The Kurile Islands) 总被引:2,自引:0,他引:2
V. G. Tarasov M. V. Propp L. N. Propp A. V. Zhirmunsky B. B. Namsakakv V. M. Gorlenko D. A. Starynin 《Marine Ecology》1990,11(1):1-23
Abstract. A marine ecosystem in the crater of the Ushishir Volcano (Kraternaya Bight, Yankich Island, the Kuriles) showing gasothcrmal activity was studied for hydrographical, hydrochemical, and biological characteristics. Maximal changes in chemical and biological characteristics were observed in the surface water layer of 0–5 m. This layer had higher water temperature, was saturated with volcanogcnic carbon dioxide (up to 2000 10-6 torr), ovcrsaturatcd with oxygen (up to 200 %), and contained high concentrations of chlorophyll a. Hydrogen sulfide was found in the surface water layer and at a depth of 15 m in the area of maximal effect of volcanic effluents.
The planktonic community is characterized by high rates of production and destruction of organic matter only in the 0–5 m layer. Daily vertical migrations of the ciliatc Mesodinium rubrum were observed, which caused "red tides".
Bacterial, algobacterial, and diatom mats developed on the bottom of the bight in the zone of gasohydrothermal vents and in areas of volcanic water seeping. The rate of organic matter production in algobacterial mats reached 33.4g C-rrr2 -d-l , chcmolithotrophy predominating. Bottom settlements had high population density and great animal biomass, which reached 10 kg m-2 in gasohydrothermal fields. They obtain sufficient energy from primary production of microphy-tobenthos, algobacterial, and bacterial mats. Bcnthic species dominant in the bight were not found off the Ushishir Islands.
Some species of macrobenthos inhabiting the Kraternaya Bight differ markedly in size and biomass from the same species found beyond the bight. 相似文献
The planktonic community is characterized by high rates of production and destruction of organic matter only in the 0–5 m layer. Daily vertical migrations of the ciliatc Mesodinium rubrum were observed, which caused "red tides".
Bacterial, algobacterial, and diatom mats developed on the bottom of the bight in the zone of gasohydrothermal vents and in areas of volcanic water seeping. The rate of organic matter production in algobacterial mats reached 33.4g C-rrr
Some species of macrobenthos inhabiting the Kraternaya Bight differ markedly in size and biomass from the same species found beyond the bight. 相似文献
54.
This study considers an important biome in aquatic environments, the subsurface ecosystem that evolves under low mixing conditions, from a theoretical point of view. Employing a conceptual model that involves phytoplankton, a limiting nutrient and sinking detritus, we use a set of key characteristics (thickness, depth, biomass amplitude/productivity) to qualitatively and quantitatively describe subsurface biomass maximum layers (SBMLs) of phytoplankton. These SBMLs are defined by the existence of two community compensation depths in the water column, which confine the layer of net community production; their depth coincides with the upper nutricline. Analysing the results of a large ensemble of simulations with a one-dimensional numerical model, we explore the parameter dependencies to obtain fundamental steady-state relationships that connect primary production, mortality and grazing, remineralization, vertical diffusion and detrital sinking. As a main result, we find that we can distinguish between factors that determine the vertically integrated primary production and others that affect only depth and shape (thickness and biomass amplitude) of this subsurface production layer. A simple relationship is derived analytically, which can be used to estimate the steady-state primary productivity in the subsurface oligotrophic ocean. The fundamental nature of the results provides further insight into the dynamics of these “hidden” ecosystems and their role in marine nutrient cycling. 相似文献
55.
56.
Seasonal Variability of Near-Surface Heat Budget of Selected Oceanic Areas in the North Tropical Indian Ocean 总被引:1,自引:0,他引:1
The results obtained from an Ocean General Circulation Model (OGCM), the Modular Ocean Model 2.2, forced with the National
Center for Environmental Prediction/National Center for Atmospheric Research reanalysis data, and observational data have
been utilized to document the climatological seasonal cycle of the upper ocean response in the Tropical Indian Ocean. We address
the various roles played by the net surface heat flux and the local and remote ocean dynamics for the seasonal variation of
near-surface heat budget in the Tropical Indian Ocean. The investigation is based in seven selected boxes in the Arabian Sea,
Bay of Bengal and the Equatorial Indian Ocean. The changes of basin-wide heat budget of ocean process in the Arabian Sea and
the Western Equatorial Indian Ocean show an annual cycle, whereas those in the Bay of Bengal and the Eastern Equatorial Indian
Ocean show a semi-annual cycle. The time tendency of heat budget in the Arabian Sea depends on both the net surface heat flux
and ocean dynamics while on the other hand, that in the Bay of Bengal depends mainly on the net surface flux. However, it
has been found that the changes of heat budget are very different between western and eastern regional sea areas in the Arabian
Sea and the Bay of Bengal, respectively. This difference depends on seasonal variations of the different local wind forcing
and the different ocean dynamics associated with ocean eddies and Kelvin and Rossby waves in each regional sea areas. We also
discuss the comparison and the connection for the seasonal variation of near-surface heat budget among their regional sea
areas.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
57.
The objective of this study was to examine the redox reactions and other transformations of mercury (Hg) species in surface waters, and the factors determining the rates of these reactions. For the redox studies completed at the Chesapeake Biological Laboratory (CBL), two isotopes (199HgII and 202Hg0) were added into different types of filtered water (fresh to seawater) to examine the oxidation and reduction reactions. Further studies of both the redox reactions and methylation/demethylation reactions of Hg were conducted with unfiltered water on board research vessels during cruises in May and July 2005 on the Chesapeake Bay and shelf. While CH3199HgII was added to allow the examination of demethylation, 201HgII was used to examine both reduction and methylation, and 202Hg0 was used to examine oxidation. Overall, the results showed that both Hg oxidation and reduction were simultaneously occurring and were photochemically mediated in the waters investigated. In contrast to the previously assumed “unreactive” nature of Hg0, the studies found that the magnitude of the rate constant for Hg0 oxidation was greater than that for reduction, indicating its importance in estuarine and coastal waters. In addition, both experiments at CBL and on board ship showed that HgII reduction was similar in magnitude, suggesting that biotic processes were relatively unimportant. While no measurable methylation occurred during the incubation period during the on board studies, concentration of CH3199HgII decreased over the time during the experiments. It appeared that the demethylation processes were not dominantly photochemically driven, but could be microbially mediated. Further studies are needed in order to help better understand Hg redox and transformations in natural water systems. 相似文献
58.
采集设备采集数据发送到值班PC机,在无人干预的情况下接收处理软件自动对数据进行回放和进一步处理,为用户提供数据产品和服务,并提供一个界面,使用户能够了解系统的运行状况,获得相关数据和状态参数。 相似文献
59.
21世纪将是全面开发利用海洋的时代,许多沿海国家将把海洋开发作为国家战略。我国是世界上人口最多的国家,陆地资源人均占有量少,更应该重视开发海洋,建设临海工业带,发展海洋农牧化,开发建设海运网络等。发展海洋经济必须走科技兴海之路,抓科技储备,改造传统产业,发展新兴产业,不断提高海洋开发生产力水平。 相似文献
60.
Morphodynamic modeling is employed in the present work to predict the long-term evolution (over the next 100 years) of typical sedimentary coasts in the western Russian Arctic. The studied objects are the coasts of Varandey (the Barents Sea), Baydaratskaya Bay and Harasavey (the Kara Sea). The model developed takes into account both the short-term processes (storm events) and long-term factors (for example, changes in sea level, inter-annual variations in gross sediment flux, lack or excess of sediment supply). Predicted and observed morphological changes in coastal profiles are shown to agree well for time scales ranging from weeks to decades. It is revealed that under given environmental conditions, the morphological evolution is strongly influenced by storm surges and associated wind-driven circulation. The water level gradient created by a surge generates a seaward flow at the bed. This outflow is shown to be an important destructive mechanism contributing to the erosion and recession of Arctic coasts. The rate of change is found to depend on both the exposure of the coast (relative to the direction of dominant winds) and its height above the sea. The open coast of Varandey is expected to retreat as much as 300–500 m over 100 years, while recession of the less exposed coasts of Baydaratskaya Bay would not exceed about 100 m/century. If long-term sediment losses are insignificant, the rate of erosion decays with time and the morphodynamic system may tend toward equilibrium. It is concluded that the expected relative sea-level rise (up to 1 m over the nearest 100 years) is non-crucial to the future coastal evolution if an erosion activity is already high enough. 相似文献