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711.
东海大陆架异养细菌的生态分布   总被引:4,自引:0,他引:4  
从海洋物质循环的观点来看,异养细菌在分解有机物质和无机化过程中起着极重要的作用。从海洋食物链的角度来看,分解各种类型有机物而得以增殖的异养细菌自身也是海洋原生动物、浮游动物及底栖动物的营养源。异养细菌在海洋生态系中占有极重要的位置。对海洋中某些细菌的代谢活动与其他海洋生物之间的相互关系的研究日益受到普遍的重视。 海洋异养细菌的生态分布资料已有不少报道。但至今尚未有人发表过东海大陆架海域海洋微生物生态调查的报告。东海大陆架海域江河交汇人海,大陆对海洋的影响极为突出,水文和底质情况复杂,水产资源丰富,因而特别富有多样化的有机物来源。调查和了解这一海域中异养细薗生态分布规律,并研究其参与物质转化过程的特异性,不仅有助于深入研究海洋生态学问题,而且对于阐述东海大陆架的特点也极有价值。本文着重讨论异养细菌在东海大陆架的生态分布特征及菌群组成的特点。  相似文献   
712.
长江口区枯、丰水期后底栖动物分布特点   总被引:2,自引:0,他引:2  
近几年来,对长江口底栖生物曾进行多次调查研究:1980-1981年进行了“中美海洋沉积作用联合研究”( Boesch等,1986;孙道元、董永庭,1986; Rhoads et al.,1985;Sun and Dong,1985);1982-1983年中国水产科学研究院东海水产研究所进行了“长江河口南岸污染对底栖生物的影响”的研究(戴国樑,1989):1985-1986年中国科学院海研究所进行了“长江口底栖生物及三峡工程对其影响的预测”的研究(刘瑞玉等,本集)。通过这些调查研究,基本掌握了长江口及其邻近水域底栖生物的概貌。 1988年4月和10月,作者又对长江口枯、丰水期后底栖动物的分布特点进行了调查研究。研究所用主要材料是在123°E以西,30°30′-32°00′N之间水域的35个取样站(图1)枯、丰水期后所获。海上取样每站以0.1㎡的表层采样器取样两次,通过0.5mm孔目的筛子冲洗后,样品在实验室内挑选、鉴定、称重和计数。  相似文献   
713.
Calanoida copepod, Drepanopus bispinosus occurred in both saline lakes, Burton ( S=40) and Fletcher ( S = 56) in Vestfold Hills, Antarctica. Evident differences between two populations in biology and physiology were observed in September and December, 1984. The population in the Burton lake was denser with stronger body and more tolerant to temperature and salinity than that in the Fletcher Lake, reflecting their possible differences of genetic or nongenetic adaptation. The population in the Burton lake has been adaptated to the lake environment, and the population in the Flethcer Lake is in the acclimatization course in the lake habitat.  相似文献   
714.
两参量的海面阻力系数模式的探讨   总被引:4,自引:0,他引:4  
汪炳祥 《海洋与湖沼》1997,28(1):96-103
从风浪的能量平衡方程出发,引进若干风要素与波要素以及波要素之间的定性关系,经演算可导出海面阻力系数(Cp)或是风速(U)和波龄(β)或是U和波高(H)的函数,然后沿用最小二乘法,终将得出4组12个回归方程。当β(或β)或H为某一给定值,惟有U为唯一参量时,所提各式均可简化为非线性方程:CD=a+b,U+c.U^2;式中a,b和c为三个经验系数,就所检验的例子而言,本文的结果与实际的符合前人的为好。  相似文献   
715.
A finite-difference scheme and a modified marker-and-cell (MAC) algorithm have been developed to investigate the interactions of fully nonlinear waves with two- or three-dimensional structures of arbitrary shape. The Navier–Stokes (NS) and continuity equations are solved in the computational domain and the boundary values are updated at each time step by the finite-difference time-marching scheme in the framework of a rectangular coordinate system. The fully nonlinear kinematic free-surface condition is implemented by the marker-density function (MDF) technique developed for two fluid layers.To demonstrate the capability and accuracy of the present method, the numerical simulation of backstep flows with free-surface, and the numerical tests of the MDF technique with limit functions are conducted. The 3D program was then applied to nonlinear wave interactions with conical gravity platforms of circular and octagonal cross-sections. The numerical prediction of maximum wave run-up on arctic structures is compared with the prediction of the Shore Protection Manual (SPM) method and those of linear and second-order diffraction analyses based on potential theory and boundary element method (BEM). Through this comparison, the effects of non-linearity and viscosity on wave loading and run-up are discussed.  相似文献   
716.
Large scale reclamation works in coastal areas of the Nakdong River plain are at various stages of progress, since early 1990's on in-situ soft marine clay deposits. These deposits are of the order of 30 to 40 m thick. A realistic rapid characterization of soft ground would ensure success of any reclamation work in this area. In order to cope with the work carried out with different agencies, it is desirable to evolve a systematic methodology. In this study, engineering properties of clays at three coastal areas, Gadukdo, Noksan and Shinho, have been generated. The analysis of data has been done within the framework of classical developments in soil mechanics. Analysis has also been made by making use of the recent developments in dealing with soft clays. The dominant factors, namely, stress, time, and environment influencing the response of clay to loading are identified.  相似文献   
717.
Oceanographic conditions off Central California were monitored by means of a series of 13 hydrographic cruises between February 1997 and January 1999, which measured water properties along an oceanographic section perpendicular to the California Coast. The 1997–98 El Niño event was defined by higher than normal sea levels at Monterey, which began in June 1997, peaked in November 1997, and returned to normal in March 1998. The warming took place in two distinct periods. During June and July 1997, the sea level increased as a result of stronger than normal coastal warming below 200 dbars and within 100 km of the coast, which was associated with poleward flow of saltier waters. During this period, deeper (400–1000 dbar) waters between 150–200 km from shore were also warmed and became more saline. Subsequently, sea level continued to rise through January 1998, mostly as a result of the warming above 200 dbars although, after a brief period of cooling in September 1997, waters below 200 dbar were also warmer than normal during this period. This winter warm anomaly was also coastally trapped, extending 200 km from shore and was accompanied by cooler and fresher water in the offshore California current. In March and April 1998, sea level dropped quickly to normal levels and inshore waters were fresher and warmer than the previous spring and flowed southward.The warming was consistent with equatorial forcing of Central California waters via propagation of Kelvin or coastally-trapped waves. The observed change in heat content associated with the 1997–98 El Niño was the same as that observed during the previous seasonal cycle. The warming and freshening events were similar to events observed during the 1957–58 and 1982–83 El Niños.  相似文献   
718.
高精度CTD剖面仪电导率传感器的研究和实验   总被引:3,自引:2,他引:3  
高精度CTD剖面仪是海洋863项目的重要组成部分,是海洋调查和水文观测必不可少的仪器,本文详细论述了CTD剖面仪中电导率传感器的研制方法和过程,并给出传感器现已达到的水平,提出还需要进一步进行的工作和深入研究的问题。  相似文献   
719.
Fluxes contributing to the particulate carbonate system in deep-sea sediments were investigated at the BENGAL site in the Porcupine Abyssal Plain (Northeast Atlantic). Deposition fluxes were estimated using sediment traps at a nominal depth of 3000 m and amounted to 0.37±0.1 mmol C m−2 d−1. Dissolution of carbonate was determined using flux of total alkalinity from in situ benthic chambers, is 0.4±0.1 mmol C m−2 d−1. Burial of carbonate was calculated from data on the carbonate content of the sediment and sedimentation rates from a model age based on 14C dating on foraminifera (0.66±0.1 mmol C m−2 d−1). Burial plus dissolution was three times larger than particle deposition flux which indicates that steady-state is not achieved in these sediments. Mass balances for other components (BSi, 210Pb), and calculations of the focusing factor using 230Th, show that lateral inputs play only a minor role in this imbalance. Decadal variations of annual particle fluxes are also within the uncertainty of our average. Long-term change in dissolution may contribute to the imbalance, but can not be the main reason because burial alone is greater than the input flux. The observed imbalance is thus the consequence of a large change of carbonate input flux which has occured in the recent past. A box model is used to check the response time of the solid carbonate system in these sediments and the time to reach a new steady-state is in the order of 3 kyr. Thus it is likely that the system has been perturbed recently and that large dissolution and burial rates reflect the previously larger particulate carbonate deposition rates. We estimate that particulate carbonate fluxes have certainly decreased by a factor of at least 3 and that this change has occurred during the last few centuries.  相似文献   
720.
S.K. Lee  H. Choi  S. Surendran 《Ocean Engineering》2006,33(17-18):2454-2465
The effects of free-surface waves on the floating structures are of great importance in the offshore industry. Among the six degrees of motions of a surface ship the absence of restoring forces in surge, sway and yaw led to critical situations for moored ships in the recent times. The order of forces in horizontal plane and their exciting frequencies are matters of interest. The resonance with the presence of moored chains led to many accidents in the recent past. The lines in dry conditions may not give good damping and in wet condition they may trigger the system to chaotic motions and jumps. Two different loading conditions of a container ship model are tested with waves in laboratory conditions in two different drafts. The mooring lines are chosen as per scale law and the energy under the response spectrum is determined from the plots. The results give new insights into the movement of a berthed ships subjected to waves. Response of the moored ship to different loading conditions in different water depths are discussed in this paper. The paper gives the order of energy due to first-order and slowly varying movement of a berthed container model in a towing tank.  相似文献   
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