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61.
To investigate the distribution,abundance,and species composition of dinoflagellate cysts in the Yellow Sea,surface sediment samples were collected at 37 sites,including the Korean dump site.Twenty-one dinoflagellate cyst taxa were identified,with the assemblages dominated mainly by Spiniferites bulloideus,Operculodinium centrocarpum,and cyst of Alexandrium catenella/tamarense type.A high frequency of O.centrocarpum in the Yellow Sea was observed for the first time,and it is likely that this can be attributed to the dynamics of the Yellow Sea Cold Water Mass and the Changjiang(Yangtze) River runoff.Total cyst concentrations ranged from 23 to 48 442 cysts/g dry weight,and high cyst concentrations were recorded adjacent to the dumping site.This result suggests that anthropogenic activities such as ocean dumping stimulate the growth of dinoflagellates in the Yellow Sea,which in turn leads to high levels of dinoflagellate cyst production. 相似文献
62.
本实验旨在研究谷朊粉、宠物级鸡肉粉、脱脂肉骨粉、豆粕和玉米蛋白粉复合替代0%(对照组,CON)、35%(FM35)、50%(FM50)、65%(FM65)、80%(FM80)鱼粉对大菱鲆(Scophthalmus maximus)生长、体组成和表观消化率的影响。设计5组等氮等能(粗蛋白52%,总能19kJ/g)的饲料,养殖鱼初重(8.63±0.01)g,养殖周期9周。结果显示,替代组体末重、增重率和特定生长率显著低于CON(P0.05),而摄食率和成活率各处理组之间没有显著变化(P0.05)。替代组饲料效率和蛋白质效率随着替代水平的升高而降低,FM65和FM80饲料效率和FM80蛋白质效率显著低于CON(P0.05)。复合蛋白替代鱼粉对鱼体水分、粗蛋白和粗脂肪没有显著影响(P0.05),但替代组鱼体灰分显著高于CON(P0.05)。除FM35干物质表观消化率与CON没有显著差异(P0.05),其他替代组的干物质和粗蛋白表观消化率均显著低于CON(P0.05)。研究表明,该比例复合蛋白源替代鱼粉水平应不超过35%。 相似文献
63.
本文研究了强酸(体积比为3︰1的硫酸与硝酸)氧化的多壁碳纳米管对水中钠离子的吸附特性,考察了温度、初始浓度、吸附时间对钠离子吸附的影响。实验结果表明:多壁碳纳米管对钠离子的吸附能力随温度升高而下降;其吸附过程符合Langmuir吸附等温模型,但是在钠离子浓度较高时多壁碳纳米管的吸附特性更符合Freundlich等温模型;在温度为274K条件下,多壁碳纳米管对钠离子的吸附能约为-5.53KJ/mol即-57.3meV;化学反应焓变约为-9.31KJ/mol,表明混酸氧化的多壁碳纳米管对钠离子的吸附过程基本为物理吸附。 相似文献
64.
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
65.
Bonggil Hyun Se-Jong Ju Ah-Ra Ko Keun-Hyung Choi Seung Won Jung Pung-Guk Jang Min-Chul Jang Chang Ho Moon Kyoungsoon Shin 《Ocean Science Journal》2016,51(3):333-342
Little is known regarding how harmful algal bloom species respond to different temperatures in terms of fatty acid production. This study examined the effects of temperature on the growth rates, cell volumes, and fatty acid concentrations and compositions of four harmful algal bloom species (HABs), Akashiwo sanguinea, Alexandrium tamarense, Chattonella ovata, and Prorocentrum minimum. The HABs species were cultured at 15, 20, 25, and 30°C in a nutrient-enriched medium. Three of the species maintained optimal growth rates over a wide range of temperatures, but A. tamarense did not. The cell volumes of each species showed little change over the temperature range. The total fatty acid concentrations in A. sanguinea, A. tamarense and C. ovata decreased as the temperature increased, but P. minimum showed no trend in this respect. Polyunsaturated fatty acids (PUFAs), the key biochemical components that maintain cell membrane fluidity and which are associated with toxicity, decreased in both concentration and proportion of total fatty acids as temperature increased, except in A. sanguinea, in which the proportion of PUFAs to the total fatty acids increased. These reductions in PUFA concentration and proportion could reduce cell membrane fluidity and toxicity in HABs; however, enhanced growth and/or ruptured cells, which are considered more toxic than intact cells, could compensate for the reduced per-cell toxicity. This phenomenon might impact on the marine ecosystem and aquaculture industry. 相似文献
66.
In past 50 years, the air temperature fluctuation was raising trend in Tarim River Basin. The annual mean temperature has increased by 0.3℃ in the whole Tarim River Basin, and by 0.6℃ in the mountain areas. With global warming, the frequency of unstable and extreme climatic events increased, glaciers retreating accelerated and snow meltwater increased have resulted in the more frequency of snow-ice disasters such as glacier debrisflow and glacier flash flood etc. Since 1980s, in the process of intense climate warming, glaciers melting intensified, ice temperature rose and glaciers flows accelerated, and lead to more glacial lakes and extending water storage capacity and stronger glacial lake outburst floods occurrence. It is proposed that the monitoring and evaluating of the impact of climate change on water resources and floods should be enhanced. 相似文献
67.
利用卫星遥感长波辐射(OLR)资料,分析黑龙江省2004年-2008年发生的几次ML 4.0以上中强地震前的OLR资料,发现地震发生前,在震中附近地区有长波辐射增强的特征,可能与强震孕育过程中的热状态有关,识别和提取卫星对地遥感红外波段的热兆信息,可望在中强地震监测预报的层面上有新的突破. 相似文献
68.
由于星载合成孔径雷达(SAR)系统工作于电离层之上,其信号不可避免地将受到电离层的影响. 背景电离层以及电离层电子密度不规则体多重散射效应可引起距离向图像质量的下降, 在强起伏情况下, 多重散射效应对信号的延迟影响不可忽略. 针对此问题, 本文提出了一种基于SAR回波信号的三频相位自适应TEC反演新方法, 利用反演的结果对电离层的影响进行校正. 给出了校正前后的点目标成像仿真, 结果显示此方法充分考虑了多重散射效应引起的TEC估计误差, 可以有效地补偿电离层对距离向成像的影响, 提高了距离向点目标图像质量. 相似文献
69.
70.