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91.
Jie GU Chiwai LI Hong YANG Yong ZHAN 《国际泥沙研究》2007,22(2):150-159
The mixing characteristics of dredged sediments of variable size discharged into cross-flow are studied by an Eulerian-Lagrangian method. A three-dimensional (3D) numerical model has been developed by using the modified k-ε parameterization for the turbulence in fluid phase/water and a Lagrangian method for the solid phase/sediments. In the model the wake turbulence induced by sediments has been included as additional source and sink terms in the k-ε model; and the trajectories of the sediments are tracked by the Lagrangian method in which the sediment drift velocities in cross-flow are computed by a multiphase particle-in-cell (MP-PIC) method and the diffusion process is approximated by a random walk model. The hydrodynamic behavior of dumped sediment cloud is governed by the total buoyancy on the cloud, the drag force on each particle and velocity of cross-flow. The cross-flow destroys more or less the double vortices occurred in stagnant ambience and dominates the longitudinal movement of sediment cloud. The computed results suggest satisfactory agreement by comparison with the experimental results of laboratory. 相似文献
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纤粒矿物粉尘体外细胞毒性研究 总被引:6,自引:0,他引:6
采用体外细胞培养技术,观察兔肺泡巨噬细胞死亡率,用丙二醛(MDA)的含量变化、乳酸脱氢酶(LDH)及超氧化物歧化酶(SOD)的活性变化来评价来自12个矿6床的6种矿物的12种结晶习性的矿物粉尘的细胞毒性,探讨其使巨噬细胞受损的机制。结果显示:沸石、硅灰石无细胞毒性,而其他的纤维状及片粒状矿物粉尘则表现出不同程度的细胞毒性,说明矿物粉尘的细胞毒性与矿物粉尘的形态有一定关系,但主要由矿物粉尘的特性所决 相似文献
95.
Distribution and germination of viable diatom resting stage cells in sediments of the East China Sea
The abundance and temporal patterns of viable diatom resting stage cells in sediments of the East China Sea in 2006 have been investigated. The abundance of viable resting stages was enumerated with the most probable number (MPN) technique. Overall, 25 diatom species (including varieties) belonging to 16 genera were detected. Viable resting stage cells were common, on the order of 103 to 106 cells/g dry mass. The abundant taxa included Skeletonema marina, S. dohrnii, Chaetoceros curvisetus and Thalassiosira spp., with Skeletonema accounting for 83.3% of the cell. The effects of temperature (10, 15, 20, 25℃), salinity (20, 25, 30, 35 psu) and light intensity (0, 300, 4 000, 8 000 lux) on the germination of resting stages in sediment samples were also determined. The results showed that light intensity had a significant positive effect on the germination of diatom resting stage cells (p <0.01) and that diatoms could not germinate in darkness. Temperature and salinity had no noticeable effects on the germination. The present study suggests that there are abundant diatom resting cells in sediments of the East China Sea, which could serve as a "seed bank" in the phytoplankton population succession and contribute to the initiation of algal blooms. 相似文献
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为了探明姬松茸提取物的体外抗病毒感染活性及其作用方式,进而为水产养殖鱼类高效抗淋巴囊肿病毒(lymphocystis disease virus,LCDV)感染活性物质的开发和鲆蝶类淋巴囊肿病的防治奠定基础,利用热水浸提和酒精沉淀法得到了5种姬松茸提取物组分(E1~5),并利用MTT、细胞病变程度观察等方法研究了5种组分对LCDV感染体外培养大菱鲆鳍细胞(turbot fin cells,TF细胞)的影响作用.细胞毒性实验结果显示,5种组分对体外培养TF细胞均无毒性.细胞病变程度结果表明,本文所得5种姬松茸提取物组分尤其是E5组分具有显著的抗LCDV感染TF细胞的活性.不同方式感染的实验结果进一步显示,5种姬松茸提取物组分抗LCDV感染TF细胞的作用可能主要是通过直接灭活病毒和/或阻断病毒吸附细胞来实现的. 相似文献
97.
2005年11月16日和27日,运用稀释法和桡足类添加法,对厦门宝珠屿海域小型浮游动物及桡足类的摄食对浮游植物生长的影响进行了研究.结果表明,各粒级浮游植物的生长率均大于小型浮游动物的摄食率,小型浮游动物对总的Chla和nano-Chla具有一致的显著的摄食作用(0.51~0.78d-1),当存在螺旋环沟藻等大型的异养甲藻时,亦能摄食micro-级浮游植物.所添加的桡足类主要摄食micro-级的浮游植物,也显著摄食小型浮游动物,16日,所添加的桡足类促进nano-级浮游植物的每天生长效应达0.03ind/dm3.说明了厦门海域小型浮游动物及桡足类的摄食共同控制着浮游植物的生长,由于桡足类的杂食性,可产生一定的营养级联效应. 相似文献
98.
Nutrient composition and distributions in coastal waters impacted by the Changjiang plume 总被引:1,自引:1,他引:0
WANG Xiulin WANG Baodong ZHANG Chuansong SHI Xiaoyong ZHU Chenjian XIE Linping HAN Xiurong XIN Yu WANG Jiangtao 《海洋学报(英文版)》2008,27(5):111-125
Four cruises were conducted during 2002--2003 in the Changjiang Estuary and adjacent coastal areas. The data presented show a clear coast to open sea gradient in nutrients related to the river inputs. Maximum values of chlorophyll a were typically observed at intermediate salinities at surface water and coincided with non-conservative decreases in nutrients along the salinity gradient, indicating that removal of nutrients was related to phytoplankton uptake. The seasonal variations of nutrient concentrations were just opposite to those of chlorophyll a, indicating that the seasonal variations of nutrients were mainly controlled by phytoplankton uptake, whereas riverine inputs merely weakened or balanced its extent. During the estuarine mixing, phosphate demonstrated some remobilization during all the four cruises; whereas both conservative and non-conservative behaviors for dissolved inorganic nitrogen and silicate were observed in the study area, indicating that both biotic and abiotic events may affect their behaviors during the estuarine mixing. Under the influence of freshwater inputs with high value of ratio of nitrogen to phosphorus, the estuarine and coastal waters impacted by the Changjiang plume were high ( 〉 30) in ratio of nitrogen to phosphorus, but rates of primary production were apparently not constrained by any kind of nutrient elements. However, the low ( 〈 1 ) ratio of silicate to nitrogen in most of the study area might be linked with the rapidly increasing frequency of harmful algal bloom (HAB) incidents in recent years in the coastal waters impacted by the Changjiang plume. 相似文献
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