Analyses of active faults, seismic activities and sea floor unstable factors of the Zhujiang River Mouth Basin and its adjacent areas

-On the basis of the data of geophysics and seismic activities, the analyses of the active faults, seismic activities and the sea floor unstable factors of the Zhujiang River Mouth Basin have been made so as to study the characteristics of the compressional subactive continental margin of Cathaysian system, arc littoral strongly active fracture zone, the division of seismic subzone and seismic zone of the continental margin of northern South China Sea, the potential focal area, and to analyze the regional stability. We consider that the Zhujiang River Mouth Basin belongs to a stable or a moderately stable region.     

A Unique Solvable Higher Order BEM for Wave Diffraction and Radiation

- For the discretization of higher order elements, this paper presents a modified integral domain method to remove the irregular frequencies inherited in the integral equation of wave diffraction and radiation from a surface-piercing body. The set of over-determined linear equations obtained from the method is modified into a normal set of linear equations by superposing a set of linear equations with zero solutions. Numerical experiments have also been carried out to find the optimum choice of the size of the auxiliary domain and the discretization on it.     

A hybrid model for numerical wave forecasting and its implementation——Ⅱ. The discrete part and implementation of the model

In the first part of the present paper we have explained why we manage to formulate another wave prediction model when so many of them, including the so-called third generation model, have already been in use. The wind-wave part of the proposed model has also been given. Now we proceed to discuss the swell part,the implementation of the model as a prediction method,mumerical experiments done with ideal wind fields and hindcasts made in the Bohai Sea,in the neighboring seas adjacent to China and in the Northwest Pacific.     

Effects of surface waves and sea spray on air–sea fluxes during the passage of Typhoon Hagupit

Air–sea exchange plays a vital role in the development and maintenance of tropical cyclones(TCs). Although studies have suggested the dependence of air–sea fluxes on surface waves and sea spray, how these processes modify those fluxes under TC conditions have not been sufficiently investigated based on in-situ observations.Using continuous meteorological and surface wave data from a moored buoy in the northern South China Sea,this study examines the effects of surface waves and sea spray on air–sea fluxes during the passage of Typhoon Hagupit. The mooring was within about 40 km of the center of Hagupit. Surface waves could increase momentum flux to the ocean by about 15%, and sea spray enhanced both sensible and latent heat fluxes to the atmosphere,causing Hagupit to absorb 500 W/m~2 more heat flux from the ocean. These results have powerful implications for understanding TC–ocean interaction and improving TC intensity forecasting.     

“Digital earth” in support of an online oceanic educational public service and popularization

According to the initial vision of "digital earth" (DE), the public should constitute a significant proportion of its users. However, to date, most of the studies and applications have focused on science, the private sector and government. A DE-supported online oceanic educational public service and popularization system, iOcean, is studied. First, the vision for the public’s engagement with "digital ocean" is described: an analysis is presented from four aspects, i.e., the space dimension, the time dimension, the state dimension and its relationship with human beings. Second, the technical framework of iOcean is discussed, including data updating and model computing, the data, the function, and the application layers. Third, two key technologies are studied in detail that will enable the construction of iOcean. More than half a million public viewers have used the current version’s website. Practical demonstrations show that iOcean can bring virtual oceans to web browsers and desktops and construct a bridge between government departments and the general public.     

Morphological characteristics in the area off eastern Taiwan Island and their tectonic implications

On the basis of bathymetric data and other geological and geophysical data obtained during the first survey conducted by Chinese Mainland in the area off eastern Taiwan Island from May to June in 2000, the morphological features of the region, the tectonic control to the seafloor topography and their tectonic implication are studied and discussed. The results have revealed that both the slope zone of the Ryukyu arc and the Ryukyu Trench present a typical morphotectonic characteristics controlled by the trench-arc system in the West Pacific Ocean. At the slope of eastern Taiwan Island the isobathic lines parallel to the coastline and distribute densely in nearly N-S direction and the slope gradient of topography is large. Such a unique feature is attributed to the collision of the Luzon arc and Eurasia continent. In the Huatung Basin, turbidity fans and submarine canyons are well developed, the formations of which are mainly related to the steep topography of the slope of the Luzon arc and the abundant s     

The interannual fluctuations of rainfall and temper-ature over China and their correlation with El Nino

The analyses of power spectra and correlation coefficients have shown that there exists a distinct quasi-3.5 -year periodicity in the fluctuations of rainfall and temperature over most parts of China, which is closely related to the oscillation of sea surface temperature in the equatorial Pacific. The structures of correlations between El Nino and precipitation and temperature fields are concretely described, and the causes for some striking responses are also explored.     

Chemical composition and petrogenesis of plagioclases in plagioclase-phyric basalts from the Southwest Indian Ridge(51°E)

Electron microprobe analysis was conducted on plagioclase from the plagioclase ultraphyric basalts(PUBs)erupted on the Southwest Indian Ridge(SWIR)(51°E) to investigate the geochemical changes in order to better understand the magmatic processes occurring under ultraslow spreading ridges and to provide insights into the thermal and dynamic regimes of the magmatic reservoirs and conduit systems. The phenocryst cores are generally calcic(An_(74–82)) and are depleted in FeO and MgO. Whereas the phenocryst rims(An_(67–71)) and the plagioclase in the groundmass(An_(58–63)) are more sodic and have higher FeO and MgO contents than the phenocryst cores. The crystallization temperatures of the phenocryst cores and the calculation of the equilibrium between the phenocrysts and the matrix suggest that the plagioclase cores are unlikely to have crystallized from the host basaltic melt, but are likely to have crystallized from a more calcic melt. The enrichment in incompatible elements(FeO and MgO), as well as the higher FeO/MgO ratios of the outermost phenocryst rims and the groundmass, are the result of plagioclase-melt disequilibrium diffusion during the short residence time in which the plagioclase crystallized. Our results indicate that an evolved melt replenishing under the SWIR(51°E) drives the eruption over a short period of time.     

In-line response of vertical cylinders in regular and random waves

The in-line response of a vertical flexibly mounted cylinder in regular and random waves is reported.Both theoretical analyses and experimental measurements have been performed.The theoretical predictions are based on the Morison equation which is solved by the incremental harmonic balance method.Experiments are then performed in a wave flume to determine the accuracy of the Morison equation in predicting the in-line response of the cylinder in regular and random waves.The interaction between waves and vibrating cylinders are investigated.     

A hybrid model for numerical wave forecasting and its implementation——Ⅰ. The wind wave model

The authors make an endeavor to explain why a new hybrid wave model is here proposed when several such models have already been in operation and the so- called third generation wave modej is proving attractive. This part of the paper is devoted to the wind wave model. Both deep and shallow water models have been developed, the former being actually a special case of the latter when water depth is great. The deep water model is exceptionally simple in form. Significant wave height is the only prognostic variable. In comparison with the usual methods to compute the energy input and dissipations empirically or by "tuning", the proposed model has the merit that the effects of all source terms are combined into one term which is computed through empirical growth relations for significant waves, these relations being, relatively speaking, easier and more reliable to obtain than those for the source terms in the spectral energy balance equation. The discrete part of the model and the implementation of the mode     

Estimating Synechococcus spp. growth rates and grazingpressure by heterotrophic nanoplankton in the English Channel and the Celtic Sea

-Marine chroococcoid phycoerythrin - containing Synechococcus spp. recently have been implicated as a substantial component of the photosynthetic picoplankton in the ocean. Although the importance of Synechococcus as food sources for heterotrophic nanoplankton are now recognized, the information about its cycling of biomass and diel patterns is limited and the methodology used varies according to different authors. A selective metabolic inhibitor method was used to allow simultanous estimation of both growth rates and grazing disappearance rates of Synechococcus. Results obtained in the English Channel show growth rates ranging from 0. 25 to 0. 72 d-1 with an average value of 0. 51 d -1and grazing disappearance rates ranged from 0. 21 to 0. 64 d-1 (mean = 0. 44 d-1). Offshore in the Celtic Sea of the Northeast Atlantic Ocean, both rates were lower than in the channel. The similarity between average growth and grazing rates suggests a rapid recycling of Synechococcus biomass. In diel pattern, Synechococc     

Distribution of chlorophyll a, photosynthesis and their relations to the environmental factors in the Central South China Sea

Some studies have been made on the variation of primary productivity in the Central South ChinaSea. This paper studies comprehensively the characteristics of chlorophyll a distributions in time andspace and the primary productivity, as well their relations to the environmental factors.Materals and methods During the comprehensive investigation in the Central South China Sea from September 1983 toDecember 1984, the distributions of chlorophyll a and primary productivity were studied. Figure 1shows the sampling stations and their range of investigation.     

Motion and Dynamic Responses of A Semisubmersible in Freak Waves

The present research aims at clarifying the effects of freak wave on the motion and dynamic responses of a semisubmersible. To reveal the effects of mooring stiffness, two mooring systems were employed in the model tests and time-domain simulations. The 6-DOF motion responses and mooring tensions have been measured and the 3-DOF motions of fairleads were calculated as well. From the time series, trajectories and statistics information, the interactions between the freak wave and the semisubmersible have been demonstrated and the effects of mooring stiffness have been identified. The shortage of numerical simulations based on 3D potential flow theory is presented. Results show that the freak wave is likely to cause large horizontal motions for soft mooring system and to result in extremely large mooring tensions for tight mooring system. Therefore, the freak wave is a real threat for the marine structure, which needs to be carefully considered at design stage.     

Sources and transport of particulate organic carbon in the Amazon River and its estuary

Stable carbon isotope ratios have been used to study the sources of particulate organic carbon(POC) in the Amazon River and its tributaries, and to examine the transport of the riverine POC intothe oceanic environment. POC in the upper reaches of the Amazon River has more positive δ ~(13)C values(--24.5‰ to -- 28.0‰) than that in the middle and lower reaches (--27.9‰ to -- 30.1‰). Theδ ~(13)C of POC from the tributaries is generally more negative than that observed in the Amazon mainchannel. This δ ~(13)C datum shows that the POC in the Amazon main channel is predominantly of terres-trial origin rather than a result of in situ production. A large range of δ ~(13)C values (--17.5‰ to -28.4‰) is observed in the Amazon Estuary and plume. and is considered as the result of the mixing     

PRELIMINARY STUDY ON GENETIC ENVIRONMENT OF SEDIMENTS OF THE EAST CHINA SEA

In order to show the relationship between the grain size model and sedimentary environment of the East China Sea, typical samples have been selected from analytical data of 1233 surface sediments, and mathematical statistic analyses of these samples have been made. Based on these analyses and combined with the compositions of the sediments and history of its formation, the authors try to divide the genetic types of the sediments of the East China Sea, with focus on the discussion of the characteristics of ancient and present hydrodynamic environments.     

COMPUTATION OF DILUTION OF RADIOACTIVE WASTE AND HEAT DISCHARGED FROM NUCLEAR POWER PLANT

- In this paper a two-dimensional unsteady shallow water equations and convection-diffusion equations have been considered to describe the diluting process of the radioactive and heat discharged from a nuclear power plant. The theory of characteristic and eccentric difference scheme has been used.In order to obtain the distribution of the concentration in far-field and near-field, three different siges of mesh have been used. The flow field has been verified with the field data, and the computed temperature in the near-field agrees with the measurements in the normal physical model test.     

Adaptation strategy for sea level rise in vulnerable areas along China's coast

I~IOXThe sea level rise threatens China's coastal plains and river deltas and makes them the vulnerable areas due to their loW elevation.Since the 1980s, the Chinese scientists have paid great attention to the problem of the sealevel rise caused by the global warming. They have analyZed and calculated the trend of the relative sea level change along the China's coast in the past 50 a. The result of study shows that therising rate of the sea level along China's coast is (1. 7 i 0. 3) rum/a.…     

Geochemical and isotopic characteristics of volcanic rocks from the northern East China Sea shelf margin and the Okinawa Trough

Volcanic rocks both from the northern East China Sea (NECS) shelf margin and the northern Okinawa Trough are subalkaline less aluminous,and lower in High Field Strength Elements (HFSE).These rocks are higher in Large Ion Lithophile Elements (LILE),thorium and uranium contents,positive lead anomalies,negative Nb-Ta anomalies,and enrichment in Light Rare Earth Elements (LREE).Basalts from the NECS shelf margin are akin to Indian Ocean Mid-Ocean Ridge Basalt (MORB),and rhyolites from the northern Okinawa Trough have the highest 207 Pb/ 204 Pb and 208 Pb/ 204 Pb ratios.The NECS shelf margin basalts have lower 87 Sr/ 86 Sr ratios,ε N d and σ 18 O than the northern Okinawa Trough silicic rocks.According to 40 K– 40 Ar isotopic ages of basalts from the NECS shelf margin,rifting of the Okinawa Trough may have been active since at least 3.65–3.86 Ma.The origin of the NECS shelf margin basalt can be explained by the interaction of melt derived from Indian Ocean MORB-like mantle with enriched subcontinental lithosphere.The basalts from both sides of the Okinawa Trough may have a similar origin during the initial rifting of the Okinawa Trough,and the formation of basaltic magmas closely relates to the thinning of continental crust.The source of the formation of the northern Okinawa Trough silicic rocks was different from that of the middle Okinawa Trough,which could have been generated by the interaction of basaltic melt with an enriched crustal component.From the Ryukyu island arc to East China,the Cenozoic basalts have apparently increasing trends of MgO contents and ratios of LREE to Heavy Rare Earth Elements (HREE),suggesting that the trace element variabilities of basalts may have been influenced by the subduction of the Philippine Sea plate,and that the effects of subduction of the Philippine Sea plate on the chemical composition of basaltic melts have had a decreasing effect from the Ryukyu island arc to East China.     

Relationship between petroleum hydrocarbon and plankton in a mesocosm experiment

~IOXWith economic development and consumer demand, oil pollutants have been one of themain marine pollutants in the coastal regal Of China. The oil-contaminated area incrsharply to 69% in 1995 and its average criterion index reached up to 2. 17 in the ChangjiangEstuary (NBEP, 1996). TO assess the influences Of the oil POllutants on the marine ~tern, it is neceSSary to develOP a mathematical kinetic model of the tranSport, distribution andfate in the marine ~teln, espeCially to esthate …     

Isolation and identification of a marine killer yeast strain YF07b and cloning of the gene encoding killer toxin from the yeast

It was found that the marine yeast strain YF07b could secrete a large amount of killer toxin against a pathogenic yeast strain WCY which could cause milky disease in Portunus trituberculatus.The marine yeast strain YF07b was identified to be Pichia anomala according to the results of routine yeast identification and 18S rDNA and ITS sequences.The gene encoding killer toxin in the marine yeast strain YF07b was amplified by PCR technology.After sequencing,the results show that an open reading frame,consisting of 1 281 bp,encoded a presumed protein of 427 amino acids.The sequence of the cloned gene was found to have 99% match with that of the gene encoding killer toxin in Pichia anomalas strain K.A signal peptide including 17 amino acids appeared in the N-terminal domain of the killer toxin.Therefore,the mature protein consisted of 410 amino acids,its molecular mass was estimated to be 47.4 ku and its isoelctronic point was 4.5.