Production of Pacific White Shrimp Polycultured with Swimming Crab at Different Densities,and Nutrient Budget in the Enclosure System     

ZHOU Yangen  BAO Weiyang  SU Yuepeng  HUANG Ming  WANG Xingqiang  YAN Binlun  MA Shen 《中国海洋大学学报(英文版)》2022,21(1):171-178

This study was to evaluate the effect of stocking densities on the nitrogen and phosphorus budgets for a polyculture of the crab Portunus trituberculatus and the Pacific white shrimp Litopenaeus vannamei.The shrimps(initial weight,0.012 g)were cultured at a density of 45 shrimp m^-2,and juvenile crabs(initial weight,0.024 g)were cultured at five densities of 0,3,6,9,and 12 crabs m^-2.The treatments were grouped as C0S45,C3S45,C6S45,C9S45,and C12S45,respectively.Water quality parameters,growth of shrimp and crabs,and nitrogen and phosphorus budget were measured.The results indicated that the shrimp performances in polyculture treatments C3S45 and C6S45 were superior to those in the crab-free treatment(C0S45).The crab in treatments C3S45 and C6S45 exhibited a significantly higher final mean weight and carapace width/length than those in treatments C9S45 and C12S45.The final size and survival of crabs had a negative correlation with the increasing crab stocking density.The contents of total phos-phorus and total nitrogen and the comprehensive contamination index values were higher in the C9S45 and C12S45 treatments than in the other treatments.The conversion ratios of nitrogen for crab and shrimp growth in treatment C3S45 were significantly higher than those in the crab-free treatment.These findings indicate that polyculturing shrimp with crabs at suitable densities can improve productivity,profitability,nutrient utilization,and the environmental quality.From the 60-day treatments,the optimal culture densi-ties were 3-6 crabs m^-2 and 45 shrimps m^-2.  相似文献   

Structure of the Potential Vorticity of an Explosive Cyclone over the Eastern Asian Region in Late November 2013     

PANG Huaji  FU Gang  LU Chungu 《中国海洋大学学报(英文版)》2022,21(2):253-263

An explosive extratropical cyclone(EC)over the Eastern Asian region that caused two shipwrecks is analyzed using ERA-Interim reanalysis data from the European Center for Medium-Range Weather Forecasts.Analyses of the evolution of the EC reveal that the positive potential vorticity(PV)at the upper-tropospheric level displays a hook-shaped structure during the mature period of the cyclone.The PV distribution forms a vertically coherent PV structure called a PV tower.The vertical distribution of the PV can induce and strengthen cyclonic circulation from the lower-to upper-levels of troposphere,which is an important deepening mechanism of explosive cyclone.The PV tower occurs approximately ten hours prior to the development of surface occlusion in the cyclone.The evolution of surface fronts closely follows the development of the horizontal upper-tropospheric PV.This tandem development is largely attributed to the ability of the positive upper-tropospheric PV and the PV tower to induce cyclonic circulation simultaneously.The kinematic wrap-up process of cyclonic circulation also accelerates the formation of warm occlusion.A conceptual model of the distributions of positive PV and potential temperature combining the perspectives of dynamic tropopause folding,PV tower,and atmospheric stability,including westward tilting and baroclinicity,is proposed.This model can illustrate the explosive deepening mechanism of ECs.The regions of convective instability and rainfall determined by this model are consistent with those identified from the actual observation.  相似文献   

Effect of Penetration Rates on the Piezocone Penetration Test in the Yellow River Delta Silt     

ZHANG Jiarui  MENG Qingsheng  ZHANG Yan  FENG Xiuli  WEI Guanli  SU Xiuting  LIU Tao 《中国海洋大学学报(英文版)》2022,21(2):361-374

Partial drainage often occurs during piezocone penetration testing on Yellow River Delta silt because of its intermediate physical and mechanical properties between those of sand and clay.Yet,there is no accurate understanding for the range of penetra-tion rates to trigger the partial drainage of silt soils.In order to fully investigate cone penetration rate effects under partial drainage condi-tions,indoor 1 g penetration model tests and numerical simulations of cavity expansion at variable penetration rates were carried out on the Yellow River Delta silt.The boundary effect of the model tests and the variation of key parameters at the different cavity ex-pansion rates were analyzed.The 1 g penetration model test results and numerical simulations results consistently indicated that the penetration rate to trigger the partially drainage of typical silt varied at least three orders of magnitude.The numerical simulations also provide the reference values for the penetration resistance corresponding to zero dilation and zero viscosity at any given normalized penetration rate for silt in Yellow River Delta.These geotechnical properties can be used for the design of offshore platforms in Yel-low River Delta,and the understanding of cone penetration rate effects under the partially drained conditions would provide some technical support for geohazard evaluation of offshore platforms.  相似文献   

银河系化学演化研究进展     

李天超  赵刚 《天文学进展》1999,17(4):334-345

银河系的形成与演化是天体物理学研究的重大前沿课题,银河系的化学演化在其中更具有极其重要的地位。随着观测资料的不断积累和理论工作的不断深入,银河系化学演化的研究取得了一系列进展。在观测方面,从太阳附近区域,整个银盘,银晕和核球等方面简要回顾了银河系化学演化模型主要观测约束的近期结果;在化学演化模型方面,回顾了银河系化学演化研究的发展历程和近期进展,并对未来的研究进行了展望。  相似文献   

东南亚金融危机对上海经济发展的影响及其对策初探   总被引：1，自引：0，他引：1  

曾刚 《世界地理研究》1999,8(2):49-56

对中国大陆经济中心之一的上海市来说,东南亚金融危机一方面造成了区域经济发展速度的降低、企业经营困难加大、产业空间结构调整计划延期,但另一方面却同时也为上海市宏观经济特别是工业经济政策调整提供了千载难逢的大好机会。从上海市经济可持续发展的要求出发,上海市应该重新认识工业在国民经济中的主导作用,重视与国内其它地区的经济合作,重视新技术研究开发,重视工业空间布局的调整和优化  相似文献   

太阳多极活动区中的磁重联、剪切低磁弧内的强电流和冕穴结构     

苏庆瑞  苏珉 《天文学报》1999,(3)

探讨了复杂磁结构上空日冕物理状态与磁剪切的关系．结果表明在强磁场的磁中性线上方磁剪切会引起具有强电流和较强等离子体压力的低磁弧．这可解释Ｙｏｈｋｏｈ 卫星的观测结果  相似文献   

晚型星HR5553,εEri和70 Oph的活动性,金属丰度和磁场的测定     

刘学富  赵刚 《天文学报》1999,40(1):16-25

对１９９５年１１月和１９９６年３、４月间观测获得的ＨＲ５５５３、７０Ｏｐｈ和εＥｒｉ给出了高分辨率,高信噪比的阶梯光栅光谱资料。确定了这３颗晚型活动星的大气参数,采用谱线细致分析方法求出了铁、锂、钙、钪、钛、钒、铬、锰、钴、镍、钇、锆和钡１３种金属元素的丰度。采用多重线统计方法测定了这３颗晚型活动星的磁场和磁场覆盖因子。  相似文献   

福建海岸的风成沉积   总被引：12，自引：5，他引：7  

李从先  陈刚  杨红君 《中国沙漠》1989,9(4):8-18

福建沿岸多处发育现代海岸风成沉积, 采用现代风砂所总结的特征作为识别标志, 研究了3000-4000年前产生的某些生物碎屑岩和3-4万年前开始形成并广泛分布的老红砂, 证明它们皆为风成, 因此晚更新世以来这里就具有风成沉积发育的条件。海岸风成沉积大规模发育出现在高海面之时, 分布也不遵循地带性规律, 这些均与沙漠地区的风砂不同。  相似文献   

京、津、唐地区中元古代沉积型海泡石粘土矿床   总被引：1，自引：0，他引：1  

郑达兴  邓寄温  邱元正  张瑞丰  徐刚  王文斌  陈保利 《地质力学学报》1995,1(2):90-96

京、津、唐地区沉积型海泡石粘土矿分布广泛。含矿岩系为蓟县系雾迷山组富镁碳酸盐岩,区域构造简单,岩浆活动微弱。研究成果表明:本区海泡石粘土矿矿点多,储量丰富,矿层厚度大,埋藏浅,易开采。矿石矿物组合简单,化学成分富镁钙低硅,物理-化学性能优良。经选矿试验海泡石粘土矿可选性良好,回收率高,成本低廉,开发前景可观。   相似文献   

海洋浮游植物的生物富集热力学模型——对疏水性污染有机物生物富集双箱热力学模型   总被引：4，自引：0，他引：4  

王修林  马延军  郁伟军  程刚 《中国海洋大学学报(自然科学版)》1998,(2)

依据疏水性有机物（ＨＯＣ）在有机相／水相之间简单物理化学分配的基本原理,提出了浮游植物对ＨＯＣ生物富集双箱热力学模型。得出浮游植物对ＨＯＣ的生物富集因子ＢＣＦ与浮游植物比表面积Ｓ,有机物正辛醇／水分配系数ｋｏｗ,有机物在水中浓度Ｃｗ之间皆存在ｌｏｇ－ｌｏｇ相关性的结论,并且由海洋浮游植物对氯代苯的生物富集实验结果验证了该模型。  相似文献