2001 Vol. 20, No. 2

Physical Oceanography,Marine Meteorology and Marine Physics
Numerical study on residual current and its impact on mass transport in the Hangzhou Bay and the Changjiang Estuary Ⅱ. Residual current and its impact on mass transport in winter
Zhu Shouxian, Dang Pingxing, Shi Fengyan, Zhu Jianrong
2001, (2): 153-169.
Some observational characteristics of residual current and mass transport in the Hangzhou Bay and the Changjiang Estuary in winter are analyzed.The residual current and its impact on mass transport are simulated with a 3-D joint model for the Hangzhou Bay and the Changjiang Estuary,in which the impacts of river flux,wind,baroclinic pressure gradient (BPG),background current in the East China Sea and tide (including M2,S2,K1 and O1) are taken into account.Based on these studies,further simulations are made to analyze the dynamical mechanisms of the observational characteristics.
Marine Meteorology
Numerical prediction experiment on Typhoon Maggie (9903)
Fong Soi Kun, Wu Chisheng, Hao I Pan, Lam Kin Hang, Ku Chi Meng, Wang Anyu, Lin Wenshi
2001, (2): 171-181.
The movement of Typhoon Maggie (9903) in June 1999 is one of the rare cases ever seen in the history.At 00U on June 6 Maggie was located at about 70 km to the southwest of Taiwan.When it arrived at the coastal region of Shanwei City (22.8°N,116.5°E),it turned suddenly to move south westward along the southern China coastal line.On June 7 Maggie finally turned to move northward,making landfall to the north of Shangchuan Island.The experimental numerical prediction system on typhoon movement that was designed based on MM5 is proved quite successful for the 48h prediction of Maggie's movement and rainfall.The mean prediction error of typhoon track is 81 km for 0~24 h and 74 km for 24~48 h.
The location of typhoon center in the initial field of the model is approximately 100 km away from the actual observations.In order to modify the location of typhoon center,a bogus typhoon was introduced into the model and the prediction of typhoon track was improved in 0~24 h time interval.But the prediction error was enlarged in 24~36 h.
We also performed a sensitivity experiment of changing the land of southern China into the ocean.It is found that the orientation of South China coastal line and the topography have no obvious effect on the movement of Typhoon Maggie.
Summer Arctic sea fog
Xie Simei, Xue Zhenhe, Jiang Dezhong, Zou Bin, Qu Shaohou
2001, (2): 183-196.
Synchronous or quasi-synchronous sea-land-air observations were conducted using advanced sea ice,atmospheric and marine instruments during China's First Arctic Expedition.Based on the Precious data from the expedition,it was found that in the Arctic Ocean,most part of which is covered with ice or is mixed with ice,various kinds of sea fog formed such as advection fog,radiation fog and vapor fog.Each kind has its own characteristic and mechanics of creation.In the southern part of the Arctic Ocean,due to the sufficient warm and wet flow there,it is favorable for advection fog to form,which is dense and lasts a long time.On ice cap or vast floating ice,due to the strong radiation cooling effect,stable radiating fog is likely to form.In floating ice area there forms vapor fog with the appearance of masses of vapor from a boiling pot,which is different from short-lasting land fog.The study indicates that the reason why there are many kinds of sea fog form in the Arctic Ocean is because of the complicated cushion and the consequent sea-air interaction caused by the sea ice distribution and its unique physical characteristics.Sea fog is the atmospheric phenomenon of sea-air heat exchange.Especially,due to the high albedo of ice and snow surface,it is diffcult to absorb great amount of solar radiation during the polar days.Besides,ice is a poor conductor of heat; it blocks the sea-air heat exchange.The sea-air exchange is active in floating ice area where the ice is broken.The sea sends heat to the atmosphere in form of latent heat; vapor fog is a way of sea-air heat exchange influencing the climate and an indicator of the extent of the exchange.The study also indicates that the sea also transports heat to the atmosphere in form of sensible heat when vapor fog occurs.
Marine Chemistry
Variations of nutrient elements and its effect on ecological environment off the Changjiang estuarine waters
Lin Yi'an, Tang Renyou, Pan Jianming, Jin Mingming
2001, (2): 197-207.
On the basis of the data obtained in two cruises during October 1997 and May 1998,the concentration distribution and the variation of present species of nutrient elements in the water masses are described.The transform mechanism of present species of nutrients and role of differmt water masses,frontal area and thermohaline transition layer on convergence or divergence and the biogeochemical cycle of nutrient elements off the Changjiang Estuary are studied.Meanwhile,the environmental capacityof nutrients is primarily estimated:they are 1.803×104t DIN and 6.18×102t PO43--P in autumn,and 4.20×102t PO43--p in spring.
Marine Geology and Geomorphology
Rare earth elements-rich phase and enriching mechanism in sediments from CC area, the Pacific Ocean
Meng Xianwei, Chen Zhihua, Wang Xiangqin, Liu Na
2001, (2): 209-214.
Compared to North American shale composition (NASC),REE contents of sediments from the CC area in the Pacific Ocean are obviously high except that cerium has equal content to that of NASC.Three-valence rare earth elements were completely enriched in phosphate-phase and cerium in iron-phase.Rare earth elements in the sediments were originally derived from seawater.During lithigenic and minerogenic processes of metalliferous nodules,three-valence rare earth elements in sediments mobilized and incorporated into sediments as authigenous biogenic-apatite,while cerium had change from Ce3+ to Ce4+ and directly precipitated from seawater and entered metalliferous nodules and caused Ceanomalies in REE pattern in sediments.
Marine Biology and Fishery
Study on optimization of parameters in a biological model
Wan Zhenwen, Qiao Fangli, Yuan Yeli
2001, (2): 215-220.
According to the data observed in a China-Japan Joint Investigation,the parameters of an ecosystem dynamics model (Qiao et al.,2000) were optimized.The values of eighteen parameters for the model were obtained,with nutrient haft saturation constant,Kn=1.4 μmol/dm3,Kp=0.129 μmol/dm3 and Ks=1.16μmol/dm3 for the diatom and Kn=0.345μmol/dm3,Kp=0.113 μmol/dm3 for the flagellate.Three proposals to set up a function for this multiple objective problem were discussed in detail.
Species composition and distribution of marine nematode community in the North Taiwan Strait
Cai Lizhe, Hong Huasheng, Zou Chaozhong, Fang Shaohua, Lü Xiaomei, Zhang Yueping
2001, (2): 221-229.
Marine free-living nematodes were investigated at 13 sampling stations divided into three transects in the northern Taiwan Strait in February 1998.One hundred species of marine nematodes belonging to 91 Genera 28 Families 3 Orders were identified and were first recorded in the northern Taiwan Strait.The dominant species were Vasostoma sp.,Sabatieria sp.1,Linhystera sp.1,Spilophorella sp.,Daptonema sp.,Halalaimus sp.and Dorylaimopsis variabilis.Their mean densities were all over 4 950 ind./m2.According to mean density at transects,marine nematode density decreased from coastal Weitou to off Minjiang Estuary,which was similar to polychaete distribution in the northern Taiwan Strait.The selective deposit feeder (1A) was the dominant food type of marine nematodes in the northern Taiwan Strait,but non-selective deposit feeders (1B) and epigrowth feeders (2A) occupied high proportion,indicating diverse feeding types of marine nematodes in the northern Taiwan Strait.Some environmental factors such as currents are discussed.
Relationship between petroleum hydrocarbon and plankton in a mesocosm experiment
Shi Xiaoyong, Wang Xiulin, Han Xiurong, Jiang Yu, Zhu Mingyuan, Chen Shang, Koshikawa Hiroshi
2001, (2): 231-240.
A mesocosm experiment was carried out from May 26 to June 1,1998 at the location of 30°52'N,122°36'E,the Changjiang Estuary,in order to measure the influence of petroleum hydrocarbon to the ecosystem,furthermore,to estimate the environmental capacity.In the experiment,it is found that the petroleum hydrocarbon can,in some degree,enhance the growth of diatom,but inhibit the growth of dinoflagellate.In general,the petroleum hydrocarbon can inhibit the growth of both phytoplankton and zooplankton,and can also inhibit the growth of total plankton (including phytoplankton and zooplankton) as well.A kinetic model was presented to estimate the uptake/release rate constants of petroleum hydrocarbon by plankton,and thereafter,the uptake and release rate constants (k1,k2),bioconcentration factor (BCF) as well as the petroleum hydrocarbon influenced uptake and release rate constants of nutrients by phytoplankton (kup,krel) were obtained.The results imply that the bioconcentration of petroleum hydrocarbon by plankton is fairly large and petroleum hydrocarbon caused no significant influence on the uptake of N-NO3,but significant influence on that of P-PO4.In addition,the application of kinetic model for the bioconcentration of volatile organic toxic compound by organism suggests that the uptake of petroleum hydrocarbon by plankton was an important process for the environmental capacity of petroleum hydrocarbon.
Structures of ovary and ovarian follicle in flathead lobster, Thenus orientalis (Lund, 1793) (Crustacea: Decapoda: Scyllarida)
Zhu Dongfa, Li Shaojing, Wang Guizhong
2001, (2): 241-249.
The ovary contains four morphological components:(1) the ovarian wall,(2) the repro-ductive epithelium,(3) the cellular layer containing oocytes,oogonia (especially for early-developing ovary) and follicle cells,and (4) the extensions of the ovarian wall.The ovarian wall and its extensions consist of blood vessels,sinuses,muscle cells and others.The extensions of the ovarian wall project into among the follicles and insert on the thick basal membrane of each follicle.
From inside to outside,the follicles are composed of four parts:(1) the oocyte,(2) the perivitelline space,(3) the follicle cells,and (4) the basal membrane.The surface of the oocyte during vitellogenesis is folded into numerous long microvilli that project into the perivitelline space between the oocyte surface and the bace of the follicle cell layer.In addition,the plasma membrane of the vitellogenic oocyte contains many pinocytotic pits.The perivitelline space is engorged with more electrondenser material as the development of the follicle.The inclusion of perivitelline space in the mature follicle is named specially as the chorion.The chorion is composed of two region,a thinner exochorion and a thicker endochorion containing electron-dense granular material.The follicle cell layer is composed of a single layer of polygonal follicle cells which exhibit higher synthetic activity.The synthetic product of the follicle cell layer is one source for the inclusion of the perivitelline space.
The structures of the ovary and ovarian follicle in T.orientalis show that the exogenously biosynthetic yolk plays important roles in the vitellogenesis.
Preliminary study on seasonal succession and development pathway of phytoplankton community in the Bohai Sea
Sun Jun, Liu Dongyan, Qian Shuben
2001, (2): 251-260.
Phytoplankton species composition and species succession were determined in 1998~1999 based on 2 nestle investigation cruises in the Bohai Sea and two monthly monitoring stations at Penglai and Changdao for 15 months.The seasonal succession and pathway of phytoplankton community in the Bohai Sea were discussed complementarily with history data.The main process of phytoplankton community development in the Bohai Sea was controlled by temperature and nutrient replenishes.There were two cell abundance peaks in an annual variation,the main peak in April and the secondary peak in September.In winter,the cell abundance was low due to the low temperature,the phytoplankton community was mainly made up of small-crled diatoms.In spring,the phytoplankton community was developed very quickly by small-celled diatom in suitable conditions of temperature and nutrients.In summer,the cell abundance decreased and big-celled diatoms became predominated.In autumn,because of the replenish of nutrient,big-celled diatoms and dinoflagellates formed another cell abundance peak.During the annual variation of phytoplankton community in the Bohai Sea,species succession was the main process of community development,the species sequence just occur at special areas and special periods.The evolution of phytoplankton community in the Bohai Sea accords with the hypothesis of Margalef's phytoplankton community of four stages.But the size feature is contrary to the hypothesis,which may be caused by nutrient replenish in autumn in Bohai Sea and the top to down control.
Studies on structure and function of digestive system of Cymatium pileare
Zhou Yongcan, Zeng Shuixiang, Su Yongquan
2001, (2): 261-270.
The digestive system of Cyrnatium pileare consists of buccal cavity,oesophagus,stomach,intestine,anus,salivary glands and liver.There is a contractible "Argobuccinum" form proboscis in the anterior extremity of its body,and the buccal cavity lies in the anterior part of the proboscis,with a pair of jaws and a piece of radular ribbon.The jaws have many neatly arranged sickleshaped sharpen denticles.Its dentition formula of radula is 2·(7) 1·(5~6) 1 (5~6)·1 (7)·2.In the middle of oesophagus,there is an expanded crop,which has the function of temporary food storage and preliminarily digesting food.The stomach is U-shaped and there are 2 entrances for liver ducts in its ventral side.The intestine is short and can be divided into 2 parts based on the structure of epithelia of their inner walls.The inner wall of foreintestine is stratified columnar epithelium,but the inner wall of hindintestine is pesudostratified columnar epithelium.The salivary gland of C.pileare is toxic gland and the toxin extracted from it plays a great role on its predation.The liver of C.pileare is compound tubuloacinar gland with mitochondrion,rough endoplasmic reticulum,Golgi complex and lysosome in its glandular cells.
Marine Engineering
Experimental study on bed-load sediment transport under irregular wave and current combined flow
Wu Yongsheng, Qin Chongren
2001, (2): 271-280.
Using an irregularly oscillating tray and flume,a series of experiments are completed to evaluate bed-load sediment transport rate under irregular wave-current coexistent fild.Testing conditions include three interaction angles 0°,45°,90° and two kinds of median sizes (0.38 and 1.10 mm).The results of transport rate show that the net sediment transport rate can be expressed approximately as the function of the maximum bottom shear stress of waves,mean shear stress of current and the grain size.
Efficient computation method for two-dimensional nonlinear waves
Wang Ke, Kang Haigui
2001, (2): 281-297.
The theory and simulation of fully-nonlinear waves in a truncated two-dimensional wave tank in time domain are presented.A piston-type wave-maker is used to generate gravity waves into the tank field in finite water depth.A damping zone is added in front of the wave-maker which makes it become one kind of absorbing wave-maker and ensures the prescribed Neumann condition.The efficiency of nmerical tank is further enhanced by installation of a sponge layer beach (SLB) in front of downtank to absorb longer weak waves that leak through the entire wave train front.Assume potential flow,the space-periodic irrotational surface waves can be represented by mixed Euler-Lagrange particles.Solving the integral equation at each time step for new normal velocities,the instantaneous free surface is integrated following time history by use of fourth-order Runge-Kutta method.The double node technique is used to deal with geometric discontinuity at the wave-body intersections.Several precise smoothing methods have been introduced to treat surface point with high curvature.No saw-tooth like instability is observed during the total simulation.
The advantage of proposed wave tank has been verified by comparing with linear theoretical solution and other nonlinear results,excellent agreement in the whole range of frequencies of interest has been obtained.
Some observational results of sea storm current
Xiu Richen, Liu Aiju, Ye Hesong, Gu Yuhe, Xu Lanying
2001, (2): 299-308.