2008 Vol. 30, No. 2
Display Method:
2008, 30(2): 1-11.
Abstract:
In this study,a hybrid Lagrangian-Eulerian(HLE)method is developed for sea ice dynamics.The method adopts the advantages of the high computational efficiency of Particle-in-Cell method(PIC)and the high numerical accuracy of Lagragian Smoothed Particle Hydrodynamics(SPH).In the HLE model,the sea ice cover is represented by a group of Lagrangian ice particles with their own thicknesses and concentrations.These ice variables are interpolated to the Eulerian grid nodes using the Gaussian int erpolation function.Thereafter,the FDM is used to determine the ice velocities on the Eulerian grid nodes,then the velocities of Lagrangian ice particles are interpolated from the grid velocity with the Gaussian function.The Lagrangian ice particles are displaced with the interpolated velocities,and the thicknesses and concentrations of ice particles are then determined based on their new locations.With the HLE numerical model,the ice ridging process in a rectangular pool is simulated,and the simulated results are validated with the analytical solution.The method is also applied to the simulation of sea ice dynamics under vortex wind field.At last,the HLE model is used to simulate the sea ice dynamics of Bohai Sea,and the simulated concentration,thickness and velocity match the satellite images and the field observed data wel.
In this study,a hybrid Lagrangian-Eulerian(HLE)method is developed for sea ice dynamics.The method adopts the advantages of the high computational efficiency of Particle-in-Cell method(PIC)and the high numerical accuracy of Lagragian Smoothed Particle Hydrodynamics(SPH).In the HLE model,the sea ice cover is represented by a group of Lagrangian ice particles with their own thicknesses and concentrations.These ice variables are interpolated to the Eulerian grid nodes using the Gaussian int erpolation function.Thereafter,the FDM is used to determine the ice velocities on the Eulerian grid nodes,then the velocities of Lagrangian ice particles are interpolated from the grid velocity with the Gaussian function.The Lagrangian ice particles are displaced with the interpolated velocities,and the thicknesses and concentrations of ice particles are then determined based on their new locations.With the HLE numerical model,the ice ridging process in a rectangular pool is simulated,and the simulated results are validated with the analytical solution.The method is also applied to the simulation of sea ice dynamics under vortex wind field.At last,the HLE model is used to simulate the sea ice dynamics of Bohai Sea,and the simulated concentration,thickness and velocity match the satellite images and the field observed data wel.
2008, 30(2): 12-19.
Abstract:
Based on observational dat a and ocean-atmosphere coupled model experiments,by analyzing the influence of the sea surface temperature(SST)anomaly main mode of the tropical Pacific ENSO and the Indian Ocean basin-wide mode(IOBM)on the South Asian High(SAH)in boreal summer,the "charge/discharge" roles of the IOBM are revealed:Firstly,the SST anomaly in the mid-east equatorial of the Pacific charges to the Indian Ocean and induces the IOBM. Being the responding mode of the Pacific ENSO, the IOBM reaches its peak phase in the next spring of the ENSO developing year and can persist from the spring to the summer. Then,the warm(cool)SST anomaly of IOBM in the spring and the summer can in turn influence the atmospheric circulation and make SAH in summer stronger(weaker)through atmos-pheric response of "Matsuno-Gill pattern" and water vapor transportation ano maly by mean south west wind of Asian summer monsoon circulation,this process is called "discharge"1. While the direct influence of the SST anomaly of the mid-east equat orial Pacific on SAH in summer is not significant,and it is pointed out that the high positive sig nificant correlation between the SAH in summer and the leading 3~12 months Niño 3 index is only a superficies,and not the result from the direct influence of the ENSO but from the "charge/discharge" role of the Indian Ocean.
Based on observational dat a and ocean-atmosphere coupled model experiments,by analyzing the influence of the sea surface temperature(SST)anomaly main mode of the tropical Pacific ENSO and the Indian Ocean basin-wide mode(IOBM)on the South Asian High(SAH)in boreal summer,the "charge/discharge" roles of the IOBM are revealed:Firstly,the SST anomaly in the mid-east equatorial of the Pacific charges to the Indian Ocean and induces the IOBM. Being the responding mode of the Pacific ENSO, the IOBM reaches its peak phase in the next spring of the ENSO developing year and can persist from the spring to the summer. Then,the warm(cool)SST anomaly of IOBM in the spring and the summer can in turn influence the atmospheric circulation and make SAH in summer stronger(weaker)through atmos-pheric response of "Matsuno-Gill pattern" and water vapor transportation ano maly by mean south west wind of Asian summer monsoon circulation,this process is called "discharge"1. While the direct influence of the SST anomaly of the mid-east equat orial Pacific on SAH in summer is not significant,and it is pointed out that the high positive sig nificant correlation between the SAH in summer and the leading 3~12 months Niño 3 index is only a superficies,and not the result from the direct influence of the ENSO but from the "charge/discharge" role of the Indian Ocean.
2008, 30(2): 20-25.
Abstract:
Using 1985-2002 ECM WF 40-years re-analyses,a preliminary study was performed on the 3-D structure and spatial-temporal distributions of the extratropical cyclones,tropical cyclones and tropical uppertro pospheric cold vortices over the subtropical northwest Pacific in summer.Results show that:(1) the different kinds of vortices are marked by a variety of three-dimensional structures,(2)the extrat ropical and tropical cyclones are mainly under 400 hPa with their high activity in the adjacent seas and weakened in the open-sea and inland directions.The upper tropospheric cold vortices appear from 400 to 100 hPa on a zonal basis,and(3)the interannual variations in the individual intensity vary among the three kinds of vortices.
Using 1985-2002 ECM WF 40-years re-analyses,a preliminary study was performed on the 3-D structure and spatial-temporal distributions of the extratropical cyclones,tropical cyclones and tropical uppertro pospheric cold vortices over the subtropical northwest Pacific in summer.Results show that:(1) the different kinds of vortices are marked by a variety of three-dimensional structures,(2)the extrat ropical and tropical cyclones are mainly under 400 hPa with their high activity in the adjacent seas and weakened in the open-sea and inland directions.The upper tropospheric cold vortices appear from 400 to 100 hPa on a zonal basis,and(3)the interannual variations in the individual intensity vary among the three kinds of vortices.
2008, 30(2): 26-32.
Abstract:
High-resolution seism ic profiles indicate that there is a large area of seafloor gas-containing sediment in the outer Lingding Bay of the Zhujiang Estuary. According to the seismic reflection characteristics of gas-containing sediment,the seismic features of shallow gas are divided into five types:an acoustic blanket,an acoustic curtain,acoustic turbidity,anirregular strong topreflection boundary,and a reflection phase pull-down. The acoustic at tenuation of ga-scontaining sediment is primarily analyzed. The result indicates that there is an attenuation peak near the frequency of 3.3 kHz. According to the comparison between surveying data and model results,it is demonstrated that the attenuation peak frequency corresponds to the fundamental resonance frequency of bubbles with 6 mm equivalent radium. The primary conclusion is drawn that the acoustic attenuation is mainly caused by the damping reso nance of bubbles with the 6 mm equivalentradium.
High-resolution seism ic profiles indicate that there is a large area of seafloor gas-containing sediment in the outer Lingding Bay of the Zhujiang Estuary. According to the seismic reflection characteristics of gas-containing sediment,the seismic features of shallow gas are divided into five types:an acoustic blanket,an acoustic curtain,acoustic turbidity,anirregular strong topreflection boundary,and a reflection phase pull-down. The acoustic at tenuation of ga-scontaining sediment is primarily analyzed. The result indicates that there is an attenuation peak near the frequency of 3.3 kHz. According to the comparison between surveying data and model results,it is demonstrated that the attenuation peak frequency corresponds to the fundamental resonance frequency of bubbles with 6 mm equivalent radium. The primary conclusion is drawn that the acoustic attenuation is mainly caused by the damping reso nance of bubbles with the 6 mm equivalentradium.
2008, 30(2): 33-37.
Abstract:
Taken the south branch of Changjiang Estuary as the study area,two bathymetric datasets,in which one is inversed by Landsat ETM+ remo tesensing image of 1999 and anot her is surveyed in 2002, were used to analyze the erosion and deposition rule of the reach and sand body movement pattern which was combined with the Changjiang River runoff discharge and sediment movement charact eristics.Results indicated that(1)from 1999 to 2002 the general variation trend of the south branch was erosion and the annual erosion amount was about 0.1926×108 m3;three sand shoal bundles,namely,Baimao sand shoal, New Liuhe sand shoal and New Liuhe sand shoal bundle were all eroded with the backing distances about 467,374 and 421 m/a respectively;(2)upper and lower Biandan sand shoals had the trend of separation because of the development of the erosion ditch between them.The changing patterns of the fiveiso baths showed that the tail of the two shoals moved downward whichled to the deeper water depth of Xinqiao Channel and lower one of its south side;(3)fixing Baimao sand shoals,and upper and lower Biandan sand shoals were very important for the channel navigation maint enance of south branch as well as the river regime stabilization of south and north river courses.
Taken the south branch of Changjiang Estuary as the study area,two bathymetric datasets,in which one is inversed by Landsat ETM+ remo tesensing image of 1999 and anot her is surveyed in 2002, were used to analyze the erosion and deposition rule of the reach and sand body movement pattern which was combined with the Changjiang River runoff discharge and sediment movement charact eristics.Results indicated that(1)from 1999 to 2002 the general variation trend of the south branch was erosion and the annual erosion amount was about 0.1926×108 m3;three sand shoal bundles,namely,Baimao sand shoal, New Liuhe sand shoal and New Liuhe sand shoal bundle were all eroded with the backing distances about 467,374 and 421 m/a respectively;(2)upper and lower Biandan sand shoals had the trend of separation because of the development of the erosion ditch between them.The changing patterns of the fiveiso baths showed that the tail of the two shoals moved downward whichled to the deeper water depth of Xinqiao Channel and lower one of its south side;(3)fixing Baimao sand shoals,and upper and lower Biandan sand shoals were very important for the channel navigation maint enance of south branch as well as the river regime stabilization of south and north river courses.
2008, 30(2): 38-50.
Abstract:
Zhelin Bay is one of the most important bays for large scale mariculture in Guangdong Province, China. Due to the increasing human population and the expanding mariculture in the last two decades,the ecological environment has greatly changed with frequent harmfulalgal blooms. We conducted a monthly survey of water content(W),organic matter(TOM),and various forms of nitrogen(N)and phosphorous (P)in the sediment from July 2002 to July 2003. The results show that water content correlated highly significantly with TOM and various forms of N and P and can be used as proxy for quick and rough estimate of these factor in the future surveys. TOM also correlated significantly with various forms of N and P,indicating that it is one of the key factors to affect the concent rations and distributions of N and P in the investigated waters. A veragetotal Kjeldhalnitrogen(TkN)and total phosphorus(TP)was(1 113.1±382.5) μg/g and(567.2±223.3)μg/g,respectively,much higher than those of similar estuaries in China and else-where. Average N and P tended to be higher inside than out side the bay,higher at aquaculture than non-aquaculture areas,and higher at fish-cageculture than oyster culture areas,suggesting that large-scale mariculture inside the bay play an important role in the eutrophication of Zhelin Bay. Various forms of N and P concent rations were higher during the warm season(July-Sept ember),due to the increased decom position and concentration of organic matter resulted from the fast growth and high mortality of the cultured species. Compared to July of 2002,TkN and TP were much higher in July of 2003,in consonance with the eutrophication of the Zhelin Bay. Since BP(biologiccal phosphorus)in the sediment includes Ex-P(exchangable phosphorus),Fe-P(iron-bouned phosphorus),OP(organic phosphorus)and some Au-P (aut higenic pho spho rus). Since Ex-P,Fe-P and OP combined accounted for 34.3%of the TP and Au-P accounted for 49.2% of the TP,BP in Zhelin Bay accounted for 34.3%to 83.5%of the T P,within the percentage range,but with a high absolute value among the est uaries.Au-P was the most important species of P and accounted for 49.2%of the TP during the investigation.Since eutrophication in the water column canlead to reduction of pH in the sediment and release of phosphorus in Au-P combined with authigenic spodiosite and calcium carbonate,high concent ration of Au-P in the sediment maybe atimebomb that can trigger avicious cycle of eut rophication and large-scale harmful algal bloom in Zhelin Bay.
Zhelin Bay is one of the most important bays for large scale mariculture in Guangdong Province, China. Due to the increasing human population and the expanding mariculture in the last two decades,the ecological environment has greatly changed with frequent harmfulalgal blooms. We conducted a monthly survey of water content(W),organic matter(TOM),and various forms of nitrogen(N)and phosphorous (P)in the sediment from July 2002 to July 2003. The results show that water content correlated highly significantly with TOM and various forms of N and P and can be used as proxy for quick and rough estimate of these factor in the future surveys. TOM also correlated significantly with various forms of N and P,indicating that it is one of the key factors to affect the concent rations and distributions of N and P in the investigated waters. A veragetotal Kjeldhalnitrogen(TkN)and total phosphorus(TP)was(1 113.1±382.5) μg/g and(567.2±223.3)μg/g,respectively,much higher than those of similar estuaries in China and else-where. Average N and P tended to be higher inside than out side the bay,higher at aquaculture than non-aquaculture areas,and higher at fish-cageculture than oyster culture areas,suggesting that large-scale mariculture inside the bay play an important role in the eutrophication of Zhelin Bay. Various forms of N and P concent rations were higher during the warm season(July-Sept ember),due to the increased decom position and concentration of organic matter resulted from the fast growth and high mortality of the cultured species. Compared to July of 2002,TkN and TP were much higher in July of 2003,in consonance with the eutrophication of the Zhelin Bay. Since BP(biologiccal phosphorus)in the sediment includes Ex-P(exchangable phosphorus),Fe-P(iron-bouned phosphorus),OP(organic phosphorus)and some Au-P (aut higenic pho spho rus). Since Ex-P,Fe-P and OP combined accounted for 34.3%of the TP and Au-P accounted for 49.2% of the TP,BP in Zhelin Bay accounted for 34.3%to 83.5%of the T P,within the percentage range,but with a high absolute value among the est uaries.Au-P was the most important species of P and accounted for 49.2%of the TP during the investigation.Since eutrophication in the water column canlead to reduction of pH in the sediment and release of phosphorus in Au-P combined with authigenic spodiosite and calcium carbonate,high concent ration of Au-P in the sediment maybe atimebomb that can trigger avicious cycle of eut rophication and large-scale harmful algal bloom in Zhelin Bay.
Magnetostratigraphy of Borehole EY02—1 in the northern outer continental shelf of the East China Sea
2008, 30(2): 51-61.
Abstract:
Rock magnetic and paleo magnetic study is under taken for the 70.20 m borehole in the East China Sea(ECS),showing that the mainmagnetic carrier is low coercivity magnetite.Magnetostratigraphy in this borehole reveals excursion at 9.62~8.58 m that is proved to be Gothenburg excursion at the beginning of Holocene with the linearly extrapolated calendarage o f 12 681~10 206 a BP from AMS 14C dating,which provides a new evidence for the aut henticity of this excursion.The stratigraphic sequences are determined for the Late Pleisto cenebased on high-resolution subbottom seismic profiles and boreholes(typical seismic profiles and boreholes in the ECS)and two rever sals are indicated.One is from 54.00 to 50.94 m with a shallow ornegative inclination,which may be an Iceland Basin event,but this is not fully discussed because of coarse sediment(which is considered as an unreliable recorder of reversal)and discontinuo us negative sample inclinations.The second continuous negative section occurs at the bottom from 70.20 to 64.31 m. Althought here is seismic profile penetrating int othe Middle Pleist ocene sequence,real boreholes reaching such long time are absent.So the bottomage is deduced according to the seismic correlation,the cycles of transg ression and regression and the time span of rever sals occurring in the Brunhes chron.The sediments of the bottom reversal are mainly coarse silty sand and fine sand,and also the length of the borehole is calculated to cross the layers of the chaotic seismic phase of MIS6 and parallel stratigraphies of marine phase underneath,so it is concluded that the bottom reversal is CR0(265~255 ka BP)happened at late MIS8.
Rock magnetic and paleo magnetic study is under taken for the 70.20 m borehole in the East China Sea(ECS),showing that the mainmagnetic carrier is low coercivity magnetite.Magnetostratigraphy in this borehole reveals excursion at 9.62~8.58 m that is proved to be Gothenburg excursion at the beginning of Holocene with the linearly extrapolated calendarage o f 12 681~10 206 a BP from AMS 14C dating,which provides a new evidence for the aut henticity of this excursion.The stratigraphic sequences are determined for the Late Pleisto cenebased on high-resolution subbottom seismic profiles and boreholes(typical seismic profiles and boreholes in the ECS)and two rever sals are indicated.One is from 54.00 to 50.94 m with a shallow ornegative inclination,which may be an Iceland Basin event,but this is not fully discussed because of coarse sediment(which is considered as an unreliable recorder of reversal)and discontinuo us negative sample inclinations.The second continuous negative section occurs at the bottom from 70.20 to 64.31 m. Althought here is seismic profile penetrating int othe Middle Pleist ocene sequence,real boreholes reaching such long time are absent.So the bottomage is deduced according to the seismic correlation,the cycles of transg ression and regression and the time span of rever sals occurring in the Brunhes chron.The sediments of the bottom reversal are mainly coarse silty sand and fine sand,and also the length of the borehole is calculated to cross the layers of the chaotic seismic phase of MIS6 and parallel stratigraphies of marine phase underneath,so it is concluded that the bottom reversal is CR0(265~255 ka BP)happened at late MIS8.
2008, 30(2): 62-69.
Abstract:
Large amounts of microfossil records have been discovered in the seafloor black smoker chimney from the Okinawa Trough. They preserve good shapes,many of which can be divided into four kinds of filamentous microfossils. It suggested that the fossils may be derived from sulfur or iron oxidation chemolithotrophic prokar yotes and fungi. Two steps of biomineralization were hypot hesized based on the comparison studies of the microbial mineralization processes:(1)biology-controlled mineralization;(2)biology-induced mineralization. At the earlier stage the biology-controlled mineralization is as a main process,at the later stage biomineralizalion is dominated by the biology-induced mineralization.The composition of the fluids and the species of the microbes will decide the types of the minerals formed.
Large amounts of microfossil records have been discovered in the seafloor black smoker chimney from the Okinawa Trough. They preserve good shapes,many of which can be divided into four kinds of filamentous microfossils. It suggested that the fossils may be derived from sulfur or iron oxidation chemolithotrophic prokar yotes and fungi. Two steps of biomineralization were hypot hesized based on the comparison studies of the microbial mineralization processes:(1)biology-controlled mineralization;(2)biology-induced mineralization. At the earlier stage the biology-controlled mineralization is as a main process,at the later stage biomineralizalion is dominated by the biology-induced mineralization.The composition of the fluids and the species of the microbes will decide the types of the minerals formed.
2008, 30(2): 70-79.
Abstract:
On the basis of the study of the fine geomorphology and high-resolution multichannel seismic profile,A conclusion that the tectonic framework of rift from Paleocene to Oligocene is the natural controlling factor to the geomorphology of slope of the northern South China Sea is drawn. The distribution of rifts and corresponding highs controls their geomorphology and evolution Besides this type and amount of matter source modify the geomorphology of slope and influence the local characteristics under the general framework. External forces,such as seismic activities and deep-water current,may control the kind of sedimentation and its microgeom orphology to some extent. These characteristics are different from both sides of the Atlantic whose rifting is from Late Jurassic to Palaeogene,so the tectonic framework of both sides of the Atlantic has less influence than source of sediment and its dispersal system On the basis of such study the slope of the northern. South China Sea can be divided into five segments from west to east: Ying Qiong slope segment,Shenhu slope segment,Zhujiang Valley slope segment,Dongsha slope segment and Taiw an Bank slope segment
On the basis of the study of the fine geomorphology and high-resolution multichannel seismic profile,A conclusion that the tectonic framework of rift from Paleocene to Oligocene is the natural controlling factor to the geomorphology of slope of the northern South China Sea is drawn. The distribution of rifts and corresponding highs controls their geomorphology and evolution Besides this type and amount of matter source modify the geomorphology of slope and influence the local characteristics under the general framework. External forces,such as seismic activities and deep-water current,may control the kind of sedimentation and its microgeom orphology to some extent. These characteristics are different from both sides of the Atlantic whose rifting is from Late Jurassic to Palaeogene,so the tectonic framework of both sides of the Atlantic has less influence than source of sediment and its dispersal system On the basis of such study the slope of the northern. South China Sea can be divided into five segments from west to east: Ying Qiong slope segment,Shenhu slope segment,Zhujiang Valley slope segment,Dongsha slope segment and Taiw an Bank slope segment
2008, 30(2): 80-91.
Abstract:
The sediment grain-size and its fractal dimension of five cores collected in the Changjiang Estucary are analyzed,and then the environmental susceptive populations of grain-size are extracted. It is shown that the sediment cores can be divided into two parts according to the vertical sedimentary structure. The to ppart(i. e.,0~12 cm)is the active layer which has been reconstr ucted frequently by dynamic environ-ments. The lower part from top of 12 cm to bottom,is char acterized by coarse-fine sediment cycles. In addition,sediment is mainly composed of two susceptive populations of grain-size with 6.0~7.2 and 40.7~57.5 Lm respectively,in which the former(i. e.,6.0~7.2 Lm)is similar to grain-size of suspended sediment from the Changjiang River and the latter(i. e.,40.7~57.5 Lm)is asso ciated with the effects of storm surges,waves and tides,dams and irrigation of river basin. The seasonal varations of suspended matter(e. g.,sediment supply quantity and grain size)from the Changjiang River may play an important role which contributes to the grain-size distribution in this area. The sediment has fractal features at 0.9~20.3 Lm interval that is consistent with the changes of sediment grain-size index. Consequently,the fractal dimension of sediment grain-size can be an important potential index containing infor mation on the environ-mental evolution.
The sediment grain-size and its fractal dimension of five cores collected in the Changjiang Estucary are analyzed,and then the environmental susceptive populations of grain-size are extracted. It is shown that the sediment cores can be divided into two parts according to the vertical sedimentary structure. The to ppart(i. e.,0~12 cm)is the active layer which has been reconstr ucted frequently by dynamic environ-ments. The lower part from top of 12 cm to bottom,is char acterized by coarse-fine sediment cycles. In addition,sediment is mainly composed of two susceptive populations of grain-size with 6.0~7.2 and 40.7~57.5 Lm respectively,in which the former(i. e.,6.0~7.2 Lm)is similar to grain-size of suspended sediment from the Changjiang River and the latter(i. e.,40.7~57.5 Lm)is asso ciated with the effects of storm surges,waves and tides,dams and irrigation of river basin. The seasonal varations of suspended matter(e. g.,sediment supply quantity and grain size)from the Changjiang River may play an important role which contributes to the grain-size distribution in this area. The sediment has fractal features at 0.9~20.3 Lm interval that is consistent with the changes of sediment grain-size index. Consequently,the fractal dimension of sediment grain-size can be an important potential index containing infor mation on the environ-mental evolution.
2008, 30(2): 92-101.
Abstract:
Tidal cycle measurements of current velocities and suspended sediment concentrations were carried out at four stations in a tidal channel(Jinshan Channel)in the northern Hangzhou Bay in China during a spring tide period in May 2005,together with water and seabed sediment sampling.Data sets were analyzed to obtain suspended sediment transport rates and resuspension fluxes.The results show that the tidal channel is dominated at the flood stage,with at idalrange increasing from the bay mouth tow ards the bay-head areas.The suspended sediment consists mainly of silts,poorly sorted and mostly negatively skewed, being consistent with the bed matter.In the central part of the channel,the net sediment transport direction which directs tow ards the bayhead differs from the residual current direction.In the other parts,the two directions are consistent,being directed tow ards the south in the east and tow ards the bay head in the west.Except for the slack water stage,the vertical distribution patterns of current speed can be described by the Kûrmûn-Prandtl model,with the calculated shear velocity having a similar trend to the vertically averaged current velocity.At most stations,the calculated apparent roughness length show satrend of increase from the beginning of flow acceleration to the end of flow deceleration during both flood and ebbphases of the tide,with extremely large values.Such a pattern cannot be explained by form drag alone;it may be result from a combined effect of high suspended sediment concentration and stratification due to vertical concentration differences within the water column.Further observations and analyses of the associated mechanisms are required to examinet his hypothesis.It is shown that the occurrence of resuspension and the measured suspended sediment concentrations have the same periodicity and the maximum concentration lags behind the maximum resuspension flux,indicating that the resuspension process represents animportant factor controlling the concentration within the water column.
Tidal cycle measurements of current velocities and suspended sediment concentrations were carried out at four stations in a tidal channel(Jinshan Channel)in the northern Hangzhou Bay in China during a spring tide period in May 2005,together with water and seabed sediment sampling.Data sets were analyzed to obtain suspended sediment transport rates and resuspension fluxes.The results show that the tidal channel is dominated at the flood stage,with at idalrange increasing from the bay mouth tow ards the bay-head areas.The suspended sediment consists mainly of silts,poorly sorted and mostly negatively skewed, being consistent with the bed matter.In the central part of the channel,the net sediment transport direction which directs tow ards the bayhead differs from the residual current direction.In the other parts,the two directions are consistent,being directed tow ards the south in the east and tow ards the bay head in the west.Except for the slack water stage,the vertical distribution patterns of current speed can be described by the Kûrmûn-Prandtl model,with the calculated shear velocity having a similar trend to the vertically averaged current velocity.At most stations,the calculated apparent roughness length show satrend of increase from the beginning of flow acceleration to the end of flow deceleration during both flood and ebbphases of the tide,with extremely large values.Such a pattern cannot be explained by form drag alone;it may be result from a combined effect of high suspended sediment concentration and stratification due to vertical concentration differences within the water column.Further observations and analyses of the associated mechanisms are required to examinet his hypothesis.It is shown that the occurrence of resuspension and the measured suspended sediment concentrations have the same periodicity and the maximum concentration lags behind the maximum resuspension flux,indicating that the resuspension process represents animportant factor controlling the concentration within the water column.
2008, 30(2): 102-110.
Abstract:
Based on size spectrum theory,field data measured by laser particle size analyzer were used to analyze Sheldon size spectra and normalized size spectra of suspended particle in the southern Taiwan Strait during summer,2004. The results showed that the patterns of Sheldon size spectra were similar at all stations in transects A and B. In normalized size spectra,the range of slopes was -0.79 to -0.65. Influenced by coastal upwelling of Taiwan Strait and upwelling around the Taiwan Shoal,the slopes were high around the high chlorophyll area or the chlorophyll maximum layer. This indicated that the process of up-welling was in favor of developing locally of biological food chain with high trophict ransfer efficiency. The in situlaser particle size analyzer could beregar ded as a basic sensor to detect finestructure for trophic transfer efficiency.
Based on size spectrum theory,field data measured by laser particle size analyzer were used to analyze Sheldon size spectra and normalized size spectra of suspended particle in the southern Taiwan Strait during summer,2004. The results showed that the patterns of Sheldon size spectra were similar at all stations in transects A and B. In normalized size spectra,the range of slopes was -0.79 to -0.65. Influenced by coastal upwelling of Taiwan Strait and upwelling around the Taiwan Shoal,the slopes were high around the high chlorophyll area or the chlorophyll maximum layer. This indicated that the process of up-welling was in favor of developing locally of biological food chain with high trophict ransfer efficiency. The in situlaser particle size analyzer could beregar ded as a basic sensor to detect finestructure for trophic transfer efficiency.
2008, 30(2): 111-116.
Abstract:
The recent years have wit nessed the continual expansion of red tides in the coastal waters of the world and its serious damage to marine fishery industries and threats to human health.For mitigation and prevention of red tide disasters,resear chers have at tached great attention to the studies on the prewarning and forecasting of red tide events.Based on the microsm experiments this paper discusses the correlation between phytoplankton diversity and apparent oxygen increment(AOI)and its application to the prewarning of red tide events.The water samples for the experiment were collected at surface waters respectively from the stations near Baozhu Islet at the inner bay and Qingyu Islet at the outer bay of Xiamen.Each water sample was subsampled into five boron-silicate glass bottles each of 500 cm3 in the filed and shipped back to land.Two groups of subsam ples were then put into a open pond of 1 m deep and let the phytoplankt on in the subsamples to grow naturally under the natural sunlight and water temperature.During the experimental period,one subsample was taken from each group for the ident ification and counting of phytoplankt on and the determination of physical and chemical parameters.The experiment results indicate that in the fo rmation process of a red tide event,phytoplankt on diversity index Hdecreased greatly while dominancy D2 increased remarkably.The papertakes Apparent Oxygen Increment(AOI,the differences between field concentration of dissolved oxygen and the saturated oxygen concentration under field temperature and salinity conditions)as the measurem entindex for phytoplankt on biomass during the red tide event in the study on the correlation between H' and D2 and phytoplankt on biomass.The results indicated that H' and AOI were highly negatively correlated and D2 and AOI highly exponentially.The correlation implies that during the red tide formation process,there is a cause and effectrelation ship between phytoplankt ondiversity and biomass.Based on the correlation modes between H' and D2 and AOI and by taking AOI index in red tide assessment as the reference,the paper proposes the index values for both H' and D2 for red tide assessment.The test by field monitoring data indicated that these two indexes can be used as the supplementary indexes in the assessment of red tide strength.
The recent years have wit nessed the continual expansion of red tides in the coastal waters of the world and its serious damage to marine fishery industries and threats to human health.For mitigation and prevention of red tide disasters,resear chers have at tached great attention to the studies on the prewarning and forecasting of red tide events.Based on the microsm experiments this paper discusses the correlation between phytoplankton diversity and apparent oxygen increment(AOI)and its application to the prewarning of red tide events.The water samples for the experiment were collected at surface waters respectively from the stations near Baozhu Islet at the inner bay and Qingyu Islet at the outer bay of Xiamen.Each water sample was subsampled into five boron-silicate glass bottles each of 500 cm3 in the filed and shipped back to land.Two groups of subsam ples were then put into a open pond of 1 m deep and let the phytoplankt on in the subsamples to grow naturally under the natural sunlight and water temperature.During the experimental period,one subsample was taken from each group for the ident ification and counting of phytoplankt on and the determination of physical and chemical parameters.The experiment results indicate that in the fo rmation process of a red tide event,phytoplankt on diversity index Hdecreased greatly while dominancy D2 increased remarkably.The papertakes Apparent Oxygen Increment(AOI,the differences between field concentration of dissolved oxygen and the saturated oxygen concentration under field temperature and salinity conditions)as the measurem entindex for phytoplankt on biomass during the red tide event in the study on the correlation between H' and D2 and phytoplankt on biomass.The results indicated that H' and AOI were highly negatively correlated and D2 and AOI highly exponentially.The correlation implies that during the red tide formation process,there is a cause and effectrelation ship between phytoplankt ondiversity and biomass.Based on the correlation modes between H' and D2 and AOI and by taking AOI index in red tide assessment as the reference,the paper proposes the index values for both H' and D2 for red tide assessment.The test by field monitoring data indicated that these two indexes can be used as the supplementary indexes in the assessment of red tide strength.
2008, 30(2): 117-123.
Abstract:
A marine fungus Penicillium crustosum 2A4-Z15,which has strong inhibition activity,w as separated from South China Sea and identified.It was treated by four biotic elicitors and five abiotic elicitors.Four biotic elicitors originated from different marine microorganism including Bacillus sp.,Penicillium sp.,Trichorderma sp.and Fucarium sp..Five abiotic elicitors included three aminoacids used as precursors and two inhibitors.The effect of different elicitors on alkaloid metabolism of the marine fung us was studied.The results show that different elicitors have different effecton alkaloid metabolism and biomass.Generally speaking,biotic elicitors have evidently positive influenceon them.Aminoacids added as precursors can show positive influence only with proper kind and concentration.Inhibitors tested both show negative influence.Alkaloid metabolism can be enhanced by 44.1% by the marine bacterial elicitor with a 10μg/cm3 concent ration added at logarithmic period
A marine fungus Penicillium crustosum 2A4-Z15,which has strong inhibition activity,w as separated from South China Sea and identified.It was treated by four biotic elicitors and five abiotic elicitors.Four biotic elicitors originated from different marine microorganism including Bacillus sp.,Penicillium sp.,Trichorderma sp.and Fucarium sp..Five abiotic elicitors included three aminoacids used as precursors and two inhibitors.The effect of different elicitors on alkaloid metabolism of the marine fung us was studied.The results show that different elicitors have different effecton alkaloid metabolism and biomass.Generally speaking,biotic elicitors have evidently positive influenceon them.Aminoacids added as precursors can show positive influence only with proper kind and concentration.Inhibitors tested both show negative influence.Alkaloid metabolism can be enhanced by 44.1% by the marine bacterial elicitor with a 10μg/cm3 concent ration added at logarithmic period
2008, 30(2): 124-129.
Abstract:
Through the examination of 377 samples collected from the Taiwan Strait,two new species of Eirenidae,i.e.Eireneoctonemalis sp.nov.and Eutimakrampi sp.no vare described.Allty pespecimens are deposited at the Department of Oceanog raphy,Xiamen University
Through the examination of 377 samples collected from the Taiwan Strait,two new species of Eirenidae,i.e.Eireneoctonemalis sp.nov.and Eutimakrampi sp.no vare described.Allty pespecimens are deposited at the Department of Oceanog raphy,Xiamen University
2008, 30(2): 130-136.
Abstract:
In order to know the embryonic development pattern of Starry flounder,Platichthys stellatus, the fertilized eggs and larval at tributes were observed and recorded by microscope(NIKON-YS100)and digital photo system(DCM 130-2.0)at the laboratory in April 2006.Eggs of starry flounder were sphericity,dissociated,buoyant,and none of oil ball with diameter 924 μm in average.With the incubated temperature 11.5~12.6℃,the blast oderm was found by 1 h 30 min after fertilized,and blastula by 9 h 30 min,gastrulae by 11 h,embryonic apparatus by 21 h.The tail separated by 40 h,heart beat and body shrink by 70 h.The larva was incubated until 89 h.The results showed that the incubated time(Ht)was strong correlated with water temperature(T/℃),the regression equation was Ht=1044.3T-0.9712(R2=0.9785).
In order to know the embryonic development pattern of Starry flounder,Platichthys stellatus, the fertilized eggs and larval at tributes were observed and recorded by microscope(NIKON-YS100)and digital photo system(DCM 130-2.0)at the laboratory in April 2006.Eggs of starry flounder were sphericity,dissociated,buoyant,and none of oil ball with diameter 924 μm in average.With the incubated temperature 11.5~12.6℃,the blast oderm was found by 1 h 30 min after fertilized,and blastula by 9 h 30 min,gastrulae by 11 h,embryonic apparatus by 21 h.The tail separated by 40 h,heart beat and body shrink by 70 h.The larva was incubated until 89 h.The results showed that the incubated time(Ht)was strong correlated with water temperature(T/℃),the regression equation was Ht=1044.3T-0.9712(R2=0.9785).
2008, 30(2): 137-146.
Abstract:
A theoretical study of diagonal wave for cesacting on partially perforated caisson breakwater with transver sewalls is performed based on the linear potential theory.An analytical method is developed to calculate the normal horizontal for cesacting on caissons,as well as the horizontal fo rcesacting on trans verse walls.The calculating results of wave forces for limited cases are the same to existing results in liter atures.The main influencing factors of wave forces are analyzed by means of numerical examples.The reduction of normal total horizontal forceacting on perforated caisson is mainly due to the upper perforat edsection of structure,where the influence of incident waves is significant.The incr easing sing lecaisson leng th is helpful to reducing total horizontal force acting on caissons.With larger incident wave angle or porous influence parameter modulus of caisson perforated front wall,the maximum total horizontal force acting on the transverse wall is larger than the corresponding normal total horizontal force acting on the caisson.At this time,the structural strength of transver sewalls should be enhanced.
A theoretical study of diagonal wave for cesacting on partially perforated caisson breakwater with transver sewalls is performed based on the linear potential theory.An analytical method is developed to calculate the normal horizontal for cesacting on caissons,as well as the horizontal fo rcesacting on trans verse walls.The calculating results of wave forces for limited cases are the same to existing results in liter atures.The main influencing factors of wave forces are analyzed by means of numerical examples.The reduction of normal total horizontal forceacting on perforated caisson is mainly due to the upper perforat edsection of structure,where the influence of incident waves is significant.The incr easing sing lecaisson leng th is helpful to reducing total horizontal force acting on caissons.With larger incident wave angle or porous influence parameter modulus of caisson perforated front wall,the maximum total horizontal force acting on the transverse wall is larger than the corresponding normal total horizontal force acting on the caisson.At this time,the structural strength of transver sewalls should be enhanced.
2008, 30(2): 147-152.
Abstract:
On the basis of the parabolic mild-slope equation for irregular water waves and two wave energy dissipation factors due to breaking wave effect,the distribution of breaking wave heights has been numerically simulated,and the numerical results have been analyzed and validated by experimental data. It is shown that the two wave energy dissipation factors due to wave breaking effect adopted here can both achieve a good agreement between the numerical and experimental results,and the breaking water wave energy dissipation factor and breaking wave index parameter play important roles on the distribution of breaking wave heights in surf zones.
On the basis of the parabolic mild-slope equation for irregular water waves and two wave energy dissipation factors due to breaking wave effect,the distribution of breaking wave heights has been numerically simulated,and the numerical results have been analyzed and validated by experimental data. It is shown that the two wave energy dissipation factors due to wave breaking effect adopted here can both achieve a good agreement between the numerical and experimental results,and the breaking water wave energy dissipation factor and breaking wave index parameter play important roles on the distribution of breaking wave heights in surf zones.
2008, 30(2): 153-160.
Abstract:
2008, 30(2): 161-168.
Abstract:
2008, 30(2): 169-174.
Abstract:
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