A Study of Lift Force and Instantaneous Velocity Field Around an Oscillating Circular Cylinder     

C.A.Greated 《中国海洋工程》1997,(4)

-Force measurements of oscillatory flow acting on a single circular cylinder have been carriedout.The experiments were done by oscillating a circular cylinder in still water.Instantaneous forces and ve-locity fields around the cylinder were measured by Particle Image Velocimetry(PIV).The Keulegan-Car-penter number(KC)varied in the range from 5 to 20 and the viscous parameter β=Re/KC was set at500(Re is Reynolds number).It was found that the strength and frequency of the lift force increased withKC number,the main frequency of the lift force being three times the frequency of the oscillatory flow atKC=20.The movement and strength of the vortices around the cylinder are discussed for differentKC numbers.  相似文献   

Retrospective analysis: bile hydrocarbons and histopathology of demersal rockfish in Prince William Sound,Alaska, after the Exxon Valdez oil spill     

Marty GD  Hoffmann A  Okihiro MS  Hepler K  Hanes D 《Marine environmental research》2003,56(5):569-584

Demersal rockfish are the only fish species that have been found dead in significant numbers after major oil spills, but the link between oil exposure and effect has not been well established. After the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, several species of rockfish (Sebastes spp.) from oiled and reference sites were analyzed for hydrocarbon metabolites in bile (1989-1991) and for microscopic lesions (1990 and 1991). Biliary hydrocarbons consistent with exposure to Exxon Valdez oil were elevated in 1989, but not in 1990 or 1991. Significant microscopic findings included pigmented macrophage aggregates and hepatic megalocytosis, fibrosis, and lipid accumulation. Site differences in microscopic findings were significant with respect to previous oil exposure in 1991 (P=0.038), but not in 1990. However, differences in microscopic findings were highly significant with respect to age and species in both years (P<0.001). We conclude that demersal rockfish were exposed to Exxon Valdez oil in 1989, but differences in microscopic changes in 1990 and 1991 were related more to age and species differences than to previous oil exposure.  相似文献   

地球海底的消减──ODP科学家着手调查哥斯达黎加洋壳的再循环     

A．H．Woods  郭玉贵 《海洋地质前沿》1997,(1)

由来自9个国家的科学家组成的研究队为研究哥斯达黎加外的活动大陆边缘在圣地亚哥登上了“JOIDES决心”号大洋钻探船．这些科学家将确定该处岩石和沉积物的年龄、物理化学性质，并将利用新开发的被称作‘随钻测井”（LWD）的测井工具．LWD技术可在钻井施工的同时在钻孔中适当的位置测量物理化学性质，并给出不受钻孔中钻具垂直运动影响的原始结果．该研究队由EliSlyer博士（加里福尼亚大学大地构造研究所所长）和GakuKimura博士（日本大皈大学地球科学系主任）领导，其他科学家分别来自美国、日本、法国、德国、大不列颠、加拿大、意…  相似文献   

Evaluation of ecotoxicological effects of endocrine disrupters during a four-year survey of the Mediterranean population of swordfish (Xiphias gladius)   总被引：2，自引：0，他引：2  

Fossi MC  Casini S  Marsili L  Ancora S  Mori G  Neri G  Romeo T  Ausili A 《Marine environmental research》2004,58(2-5):425-429

In this project we investigated the ecotoxicological effects of endocrine disrupters in a four-year survey of the Mediterranean population of swordfish (Xiphias gladius). In the Mediterranean environment, top predators, such as swordfish, accumulate high concentrations of polyhalogenated aromatic hydrocarbons (PHAHs) and toxic metals, potentially incurring high toxicological risk. The effects of organochlorines and trace elements (Hg, Cd and Pb) in 192 swordfish specimens, caught in the Strait of Messina, Sicily, Italy, were investigated using vitellogenin (Vtg), zona radiata proteins (Zrp) and CYP1A (BPMO, EROD) activities. Vtg and Zrp were found to be dramatically induced in some adult male specimens, suggesting that this species is highly exposed to estrogens in the Mediterranean Sea. A role of organochlorines in this induction phenomenon is suggested by the statistically significant correlations between Zrp in plasma and PCB concentrations in muscle (p<0.032) and Vtg in plasma and PCB concentrations in liver (p<0.034) of male specimens. Levels of trace elements in liver were in the following ranges: Hg 1-22, Cd 1-28 and Pb 0-1.6 ppm d.w. These data indicate potential reproductive alterations in large pelagic fish and suggest the need for continuous monitoring to avoid reductions in the population of this fish species of high commercial and ecological interest.  相似文献   

Persistence of yessotoxin under light and dark conditions     

Mitrovic SM  Hamilton B  McKenzie L  Furey A  James KJ 《Marine environmental research》2005,60(3):397-401

The change in concentration of the disulfated polyether yessotoxin (YTX) produced by a culture of the marine dinoflagellate Protoceratium reticulatum was measured in laboratory experiments under light and dark conditions. Experimental cultures were inoculated and grew at a growth rate of 0.14 d(-1) until stationary phase was reached, after approximately 21 days. Cultures were maintained in the stationary phase until 31 days after inoculation. Cells of P. reticulatum contained a concentration of approximately 10-15 pg YTX cell(-1) during stationary phase but this was considerably lower (<5 pg cell-1) during the growth phase. Low amounts of 45-hydroxy-YTX were also detected. At day 32, P. reticulatum was killed by cooling to 1 degrees C (confirmed microscopically) and YTX concentrations were measured periodically under light and dark conditions. YTX concentrations decreased rapidly to approximately 10% of the initial concentration within the first 3 days and depleted to near zero within a week in the light treatment. In the dark environment, YTX persisted longer with approximately 10% of the initial YTX concentration still remaining after 18 days.  相似文献   

北大西洋和近极地海盆再沉积超微化石：Heinrich事件和大洋环流的意义     

Rahman  A 蓝先洪 《海洋地质前沿》1996,(1):12-13

北大西洋和近极地海盆再沉积超微化石：Ｈｅｉｎｒｉｃｈ事件和大洋环流的意义Ａ．ＲａｈｍａｎＨｅｉｎｒｉｃｈ（１９８８）在大西洋东北面的最后冰）沉积物中发现了６层富含冰携碎屑的短期ｌｉ－ｊＪ隔，现在人们称之为“Ｈｅｉｎｒｉｃｈ间隔（Ｈ）”、在这些间隔中，...  相似文献   

意大利Maiella碳酸盐平台上始新世一渐新世与陆架边缘进积和出露有关…     

Vecsei  A 孙萍 《海洋地质前沿》1997,(12):15-17

  相似文献   

Histological and morphological alterations induced by copper exposure in Laeonereis acuta (Polychaeta, Nereididae)     

Geracitano LA  Luquet C  Monserrat JM  Bianchini A 《Marine environmental research》2004,58(2-5):263-267

Laeonereis acuta (Polychaeta, Nereididae) was collected in an unpolluted (UP) and an polluted (P) site at the Patos Lagoon estuary (Southern Brazil) and maintained under control conditions (UPC and PC, respectively) or exposed to waterborne copper (UPCu and PCu; 500 microg Cu/l), for 48 h. Four groups (aaUPC, aaPC, aaUPCu, and aaPCu) were also pre-exposed for 48 h to ascorbic acid (aa; 0.1 mM) before copper exposure. Histological and morphological alterations, as well as oxygen consumption changes were evaluated. Independently of the sampling site and the pre-exposure to the ascorbic acid, morphological abnormalities were evident in more than 80% of worms exposed to copper. Conspicuous histological changes (coeloma obliteration, cuticle separation from the epidermis, and absence of dorsal vessel) were also observed. In addition, PCu worms showed loss of the digestive epithelium and coiling behavior. Similar oxygen consumption values were observed in control and copper exposed worms.  相似文献   

Cell responses to xenobiotics: comparison of MCF7 multi-drug- and mussel blood cell multi-xenobiotic-defense mechanisms     

Marin M  Legros H  Poret A  Leboulenger F  Le Foll F 《Marine environmental research》2004,58(2-5):209-213

Multi-drug resistance (MDR) in MCF7 breast cancer cells and multi-xenobiotic resistance (MXR) in mussel (Mytilus edulis) blood cells (MBC) are well known mechanisms that contribute to the decrease in intracellular concentrations of many unrelated but cytotoxic compounds. In the present work, we have carried out comparative investigations of the MDR/MXR protective mechanisms using a rapid colorimetric assay for cell viability and calcein accumulation for MDR/MXR activities. These studies were performed using cultured MCF7 and MBC before and after in vitro exposure to xenobiotics. Our results indicate that a 5-day exposure to doxorubicin or vincristine decreased calcein accumulation in MBC which is consistent with an induction of multi-xenobiotic resistance. The increase in calcein accumulation provoked by 1-h treatment with 50 microM verapamil was much lower in MBC when compared to the P-glycoprotein overexpressing MCF7 cell line. We conclude that such microplate assays could be used in primary cultures of MBC to estimate the effects of various chemicals on MXR activity.  相似文献   

威德尔海西缘深部与底层海流     

A.L.Gordon胡季平  刘健 《海洋地质前沿》1994,(6):13-15

南大西洋威德尔环流是环南极海流中最大的气旋向极环流，其西部覆盖威德尔海。威德尔海的海冰变化不定，而热量和湿气在垂向上的强劲流动则在威德尔环流和海水之上形成寒冷的极地大气，这使威德尔环流成为南极底层水(AABW)的一个主要源地．在冬季，海冰几乎覆盖整个威德尔环流；在夏季，除威德尔海西部外，  相似文献