Effect of UV-B radiation on the population dynamics of the rotifer Brachionus urceus     

WANG Jinhe  FENG Lei  TANG Xuexi 《海洋学报(英文版)》2011,30(2):113-119

The effect of UV-B radiation enhancement at experimental doses of 0.00,0.24,0.48,0.72,0.96,and 1.20 kJ/m 2 on the population dynamics of the rotifer Brachionus urceus feeding on the alga Chlorella sp.was studied under controlled laboratory conditions using clonal culture and life-table techniques.The results show that UV-B radiation treatment significantly shortened the survival time of the rotifer (P <0.05): The longest survival time (336 h) occurred in the control (0.00 kJ/m 2 ) while the shortest (222 h) occurred when exposed to the highest UV-B radiation treatment (1.20 kJ/m 2 ).The fecundity of the rotifer B.urceus was enhanced by the lower UV-B radiation treatment (0.24 and 0.48 kJ/m 2 ) but inhibited by the higher treatments (0.96 and 1.20 kJ/m 2 ).Life expectancy also was obviously affected by UV-B radiation (P <0.05).The highest life expectancy occurred in the control (0.00 kJ/m 2 ),and it became shorter with increasing doses of UV-B radiation.The resutls in the present study indicate that the life expectancy of the rotifer B.urceus can be used as an indicator for UV-B radiation enhancement.  相似文献   

Application of a BEM time stepping algorithm in understanding complex unsteady propulsion hydrodynamic phenomena     

Gerasimos K. Politis 《Ocean Engineering》2011,38(4):699-711

We solve the problem of unsteady potential flow around a system of arbitrarily moving rigid or flexible, lifting or non-lifting bodies, in an infinite fluid free of distributed vorticity. For the solution we use a time stepping algorithm and a potential based formulation of the corresponding free BVP. Nonlinear free shear layer dynamics are included in our modeling. This is a major innovation in treating complex unsteady propulsion problems since no simplifying assumptions (like that of a helicoidal wake) are used regarding the wake model. Bilinear quadrilateral elements are used to describe body and shear layer geometry at each time t. Three types of Kutta conditions can be alternatively applied for the determination of the shed vorticity from lifting bodies. The theoretical and numerical aspects of the method are presented followed by a number of applications, elucidating the qualitative and quantitative physical characteristics of a number of complex unsteady propulsion problems.  相似文献   

Dynamic factor analysis considering elastic boom effects in heavy lifting operations     

Kwang-Phil Park  Ju-Hwan Cha  Kyu-Yeul Lee 《Ocean Engineering》2011,38(10):1100-1113

The dynamic factor is the ratio of the maximum dynamic load to the static load acting on the wire ropes between the boom of a floating crane and a cargo. In this paper, the dynamic factor is analyzed based on dynamic simulations of a floating crane and a cargo, considering an elastic boom. For the simulation, we designed a multibody system that consists of a floating crane barge, an elastic boom, and a cargo connected to the boom through wire ropes. The dynamic equations of motion of the system are based on flexible multibody system dynamics. Six-degree-of-freedom motions are considered for the floating crane and for the cargo, and three-dimensional deformations for the elastic boom. The hydrostatic force, the hydrodynamic force, the gravitational force, and the wire rope forces are considered as external forces. The dynamic factor is obtained by numerically solving the equation. The effects of the elastic boom on heavy cargo lifting are discussed by comparing the simulation results of an elastic boom and a rigid boom.  相似文献   

Anthropogenic impacts on the water and salt budgets of St Lucia estuarine lake in South Africa     

Robynne A. Lawrie  Derek D. Stretch 《Estuarine, Coastal and Shelf Science》2011

Lake St Lucia in South Africa is part of a UNESCO World Heritage site and a Ramsar wetland of international importance. Like many coastal wetlands worldwide, anthropogenic activities including catchment land-use changes, water diversions/abstractions, and manipulation of the mouth state have significantly affected its functioning over the past century. Questions concerning its sustainability have motivated a re-evaluation of management decisions made in the past and of options for the future. A model for the water and salt budgets has therefore been used to investigate “what if” scenarios in terms of past anthropogenic interventions. In particular, simulations allow us to evaluate the effects of diverting the Mfolozi river from St Lucia on the functioning of the system and on the occurrence of various water level/salinity states that drive the biological functioning of the ecosystem. In the past, when the St Lucia estuary and the Mfolozi river had a combined inlet, the mouth was predominantly open. The lake had relatively stable water levels but variable salinities that increased during dry conditions due to evaporative losses and saltwater inflows from the sea. If the mouth closed, the Mfolozi flow was diverted into the lake which reduced salinities and maintained or increased water levels. Simulations indicate that without a link to the Mfolozi the lake system would naturally have a mainly closed inlet with lower average salinities but more variable water levels. During dry conditions water levels would reduce and result in desiccation of large areas of the lake as has recently occurred. We conclude that the artificial separation of the St Lucia and Mfolozi inlets underpins the most significant impacts on the water & salt budget of the lake and that its reversal is key to the sustainability of the system.  相似文献   

Application of a vessel monitoring system to advance sustainable fisheries management—Benefits received in Taiwan   总被引：1，自引：0，他引：1  

Shui-Kai Chang 《Marine Policy》2011

Vessel monitoring systems (VMS) are considered important instruments for fisheries monitoring, control and surveillance (MCS) to reverse the current depressed state of the world’s fisheries, and have been mandated worldwide by fishery management agencies. The essential function of the system is to provide near-real time vessel position; the potential applications could, however, be more than that. This study explores the additional benefits, with practical examples, that Taiwan has received from implementing the system: in improving the quantity and quality of logbooks recovered, obtaining access to fishery-independent fishing effort estimates and prompt catch/effort reporting, enabling the possibility of regional management and understanding of both fleet dynamics and vessel behavior, and increasing efficiency of vessel safety protection. For other distant-water fishing nations, Taiwan’s experiences serve to demonstrate how the application of VMS technology can advance sustainable fisheries management.  相似文献   

Impact of mega-scale sand extraction on tidal dynamics in semi-enclosed basins: An idealized model study with application to the Southern North Sea     

Wiebe P. de Boer  Pieter C. Roos  Suzanne J.M.H. Hulscher  Ad Stolk 《Coastal Engineering》2011

Long-term considerations of repeated and increasing sand extraction on the Netherlands Continental Shelf (North Sea) may lead to the creation of a mega-scale extraction trench in front of the Dutch coast (length hundreds of km, width over 10 km, depth several m). We investigate the impact of such a huge topographic intervention on tidal dynamics, which is a key aspect in hydrodynamics, and indirectly also affecting morphodynamics and ecology.  相似文献   

浙闽沿岸流消退时期的浮游植物群落结构特征     

王雨  林茂  林更铭  项鹏 《海洋通报》2011,30(2):221-225

浙闽沿岸流对台湾海峡的水文环境意义重大.依据国家海洋局"908"补充调查专项,通过对覆盖浙闽沿岸流海洋锋面过程的海洋生物调查研究,于2008年4月实施针对浙闽沿岸流消退时期(春季)台湾海峡锋面海域的浮游植物取样分析.结果共记录3门41属86种,其中硅藻35属76种.甲藻5属9种,蓝藻1属1种.种类组成以暖水性种类和广布...  相似文献   

浮基多体系统在波浪中展开的数值模拟   总被引：1，自引：1，他引：0  

江召兵  杜乃娟  陈徐均  洪娟 《海洋工程》2011,29(4):114-118

浮基多体系统在波浪中展开过程的顺序与快慢对系统的运动响应和连接处的力矩有较大影响。介绍了建立在齐次矩阵方法基础上的浮基多体系统时域运动求解,并对一具体浮基系统进行了建模和数值模拟,分析了上部机构以一定规律快速展开和慢速展开时系统的运动响应。结果表明,把齐次矩阵方法引入浮基多体系统的求解领域,其符号推导方便,运动学和动力学方程表达式变得相当简洁,而且编制程序也相对简便快捷。在相同波浪周期的情况下,多体系统的最大横摇角响应与波高正相关;在相同波高情况下,长周期的最大横摇响应要比短周期小;相对于波周期,波高对系统横摇响应的影响要大的多。  相似文献   

Geochemistry and genesis of magmatic PGE-bearing Cu-Ni sulphide deposit in Wadi Bayhan,southeastern Yemen     

Moteea A.Al-Shameery  M.Alqadasi  M.Mattash 《东北亚地学研究》2011,(1)

The Wadi Bayhan mafic-ultramafic intrusions associated with magmatic PGE-bearing Cu-Ni sulphide deposit are located in the south margin of the Arabian-Nubian Shield,SW Yemen.The intrusions consist of dunite,olivine-pyroxenite,lherzolite,hornblendite,gabbro and gabbronorite.The dunite and lherzolite are the main host rock for the Cu-Ni ores.The new data of the chemical compositions of the rocks have SiO2(50%-53.6%),Al2O3(0-32%) and MgO(4%-28%),and relatively low TiO2(0-3.2%) and K2O+Na2O(0.04%-5.2%).The geoc...  相似文献   

德州市城区地热水动态与开采量关系          下载免费PDF全文

杨询昌  王成明  冯守涛  柴建林 《山东国土资源》2011,27(7):25-28

德州市城区多年来因地热水大量开采,地热水位持续下降,并形成了以德州市城区为中心的地热水降落漏斗。根据区内馆陶组热储多年地热水动态与开采量进行分析研究,查明了区内地热水动态与开采量的相互关系,进一步揭示了人为活动的影响,建立了区内地热水动态与开采量相关方程,并通过方程曲线态势分析,提出了区内地热集中开采区馆陶组热储地热水预警开采量,为区内地热资源的可持续开发利用提供了科学依据。  相似文献