The research on sea ice resources is the academic base of sea ice exploitation in the Bohai Sea. According to the ice-water spectrum differences and the correlation between ice thickness and albedo, this paper comes u...The research on sea ice resources is the academic base of sea ice exploitation in the Bohai Sea. According to the ice-water spectrum differences and the correlation between ice thickness and albedo, this paper comes up with a sea ice thickness inversion model based on the NOAA/AVHRR data. And then a sea ice resources quantity (SIQ) time series of Bohai Sea is established from 1987 to 2009. The results indicate that the average error of inversion sea ice thickness is below 30%. The maximum sea ice resources quantity is about 6×109 m3 and the minimum is 1.3×109 m3. And a preliminary analysis has been made on the errors of the estimate of sea ice resources quantity (SIQ).展开更多
The ice conditions in the Bohai Sea and the northern Huanghai Sea greatly change from year to year with winter climate. Ice only covers below 15% of the the waters during the wannest win-ter, while it covers more than...The ice conditions in the Bohai Sea and the northern Huanghai Sea greatly change from year to year with winter climate. Ice only covers below 15% of the the waters during the wannest win-ter, while it covers more than 80% during the coldest winter. Ice observation and data acquisition are outlined in the paper. The ice-covered area, the position of ice edge and the ice grades give indication of the ice conditions. The local climate of the waters can be expressed by using the air temperature of the stations of Dalian and Yingkou. The variation of the ice condition indexes with the monthly mean air temperature at Dalian from 1952 to 2000 is shown, as well. The local climate and ice conditions in the waters are affected by many factors,such as, evolution of the general atmospheric circulation and the solar activity. The delayed correlation between the ice conditions and lots of the affecting factors is analysed in the paper. The ice conditions are continuously mild since the 1990s, that is relative to the tendency of the global warming. The ice condition variation of the Bohai Sea is related to the El Nino event and the sunspot period. The seasonal evolution of the ice conditions is also described in the paper.展开更多
A hierarchical diversity index—taxonomic distinctness index Δ +, which was first defined by Warwick and Clark in 1998, was employed to evaluate the pollution status of the Bohai Sea with freeliving marine nematodes...A hierarchical diversity index—taxonomic distinctness index Δ +, which was first defined by Warwick and Clark in 1998, was employed to evaluate the pollution status of the Bohai Sea with freeliving marine nematodes. The result showed that the Bohai Bay and other coastal sampling sites might be affected by oil and gas production and other anthropogenic influences. In other words,anthropogenic disturbance was affecting this component of the benthos in these locations. And most offshore sampling sites in the middle of the Bohai Sea were clear and unpolluted.展开更多
A grid of 22 stations, giving a broad geographic coverage of the Bohai Sea and the Bohai Strait was selected. Undisturbed sediments were collected from sampling stations during cruises in June 1997, in September/Octob...A grid of 22 stations, giving a broad geographic coverage of the Bohai Sea and the Bohai Strait was selected. Undisturbed sediments were collected from sampling stations during cruises in June 1997, in September/October 1998 and again in April/May 1999. Based on the results of Juario (1975), the average biomass, 0.404 g/(m2a) of meiofauna (including nematode, harpacticoida, bivalve larvae, polycheata and kinorhyncha) in the Bohai Sea is given and accounts for 4.5 percent of the macrofauna in the Bohai Sea. The horizontal distribution of the biomass of meiofauna showed that it was higher at the stations of middle east part of the Bohai Sea and the strait in 1998 and 1999 cruises and it decreased at the stations near to the strait mouth and increased at Station B1 in 1999 cruise. The annual average production in the Bohai Sea is 3.636 g/m2 calculated in term of the formula P = 9B. Compared with the biomass of other sea areas in the world, the biomass of the Bohai Sea is similar but slightly lower. The individual average dry weight of nematodes given by different authors is analyzed.展开更多
Based on the comprehensive collection of the field observed salinity of the Bohai Sea (BHS) and the northern Huanghai Sea (NHS) from the 1950s to the present, the patterns of 10-years-averaged salinity at the diff...Based on the comprehensive collection of the field observed salinity of the Bohai Sea (BHS) and the northern Huanghai Sea (NHS) from the 1950s to the present, the patterns of 10-years-averaged salinity at the different layers in the recent five decades (the 1950s, the 1960s, the 1970s, the 1980s and the 1990s) are obtained by the spatial-temporal interpolation technique with the scrupulous data quality control in this study. Then, by combining the spatial-temporal interpolation technique with successive correction method, the annual distributions of salinity both in the BHS and in the NHS are obtained as well. The data analyses indicate that the overall salinity in the BHS and the NHS increases from the 1960s till the present, with the increase of annual mean salinity of 0.04 psu from the 1950s, and the maximum increase rate of salinity is about 0.14 psu/a in the Bohai Bay. The high salinity tongue extended significantly from the NHS into the BHS. The intensified eastern wind field is related to the western intrusion of the NHS warm current, which probably leads to the moving forward of the high salinity water mass into the BHS. However, it is rather different from the salinity distribution characteristics between the 1950s and the 1960s. The extensive precipitation in the 1960s could lead to an increase in the discharge of the Huanghe River, which might result in the decrease of salinity in the BHS. But the salinity isoline of 32 in the NHS still extended significantly into the BHS in the 1960s. Since the 1980s, the patterns of salinity distribution have changed thoroughly. The salinity in the central area of the BHS was low, while the salinity in the Bohai Bay and the Liaodong Bay was higher than the other regions with its horizontal salinity gradient decreasing in the 1980s. The Empirical Orthogonal Function Analysis (EOF) is also conducted to study the interannual salinity variability of the BHS and the NHS. The correlation coefficient between the time coefficient series of the main mode and the Huanghe River discharge can reach-64.57%. It can be concluded that salinity variation of the BHS and the NHS has strong negative correlation with the Huanghe River discharge.展开更多
On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made b...On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made by using the method of fuzzy cluster from the modified characteristic of water masses in the shallow water area. In this paper, the basic features, growth and decline patterns of water masses in relation to fishing grounds in the whole shelves of the Bohai Sea, the Huanghai Sea and the East China Sea are discussed with emphasis.展开更多
Deoxygenation has frequently appeared in coastal ecosystems over the past century due to the joint infl uence of increasing anthropogenically induced nutrient inputs and global warming.The semi-enclosed Bohai Sea is a...Deoxygenation has frequently appeared in coastal ecosystems over the past century due to the joint infl uence of increasing anthropogenically induced nutrient inputs and global warming.The semi-enclosed Bohai Sea is a typical system that is prone to deoxygenation,with regular hypoxia events consistently recorded in recent decades.Based on in-situ observation data collected in large-scale voyage surveys in the Bohai Sea during 2008-2017,the seasonal variability in dissolved oxygen(DO)and its controlling mechanisms were studied.The results indicated that in spring and autumn,the DO distributions exhibited similar spatial patterns in the surface and bottom layers,while in summer,its spatial distribution was characterized by large-scale oxygen-poor zones distributed off the Qinhuangdao Coast and the central southern Bohai Sea in the bottom layer.The controlling mechanisms of the DO distribution varied from season to season.Spring and autumn DO distributions were dominated by the seawater temperature.Under the combined eff ects of stratifi cation and decomposition,the summer bottom DO exhibited dual-core distribution.On the one hand,stratifi cation could greatly impede vertical mixing,resulting in reduced bottom DO replenishment.On the other hand,the increased bottom organic matter intensifi ed the decomposition processes,inducing massive DO consumption and elevated dissolved inorganic nitrogen concentrations.In addition,the stronger stratifi cation might be the reason for the more severe deoxygenation in the southern oxygen-poor zones in summer.Our study provides guidance for an in-depth understanding of the DO seasonality in the Bohai Sea and the mechanisms that modulate it and for the improvement of hypoxia forecasts in ocean models.展开更多
The carbon cycle of lower trophic level in the Bohai Sea is studied with a three-dimensional biological and physical coupled model. The influences of the processes (including horizontal advection, river nutrient load,...The carbon cycle of lower trophic level in the Bohai Sea is studied with a three-dimensional biological and physical coupled model. The influences of the processes (including horizontal advection, river nutrient load, active transport etc. ) on the phytoplankton biomass and its evolution are estimated. The Bohai Sea is a weak sink of the CO2 in the atmosphere. During the cycle, 13.7% of the gross production of the phytoplankton enter the higher trophic level and 76.8 % of it are consumed by the respiration itself. The nutrient reproduction comes mainly from the internal biogeochemical loop and the rem-ineralization is an important mechanism of the nutrient transfer from organic form to inorganic. Horizontal advection decreases the total biomass and the eutrophication in some sea areas. Change in the nutrient load of a river can only adjust the local system near its estuary. Controlling the input of the nutrient, which limits the alga growth, can be very useful in lessening the phytoplankton biomass.展开更多
-Based on a two-dimensional numerical M2 tidal model of the Huanghai and Bohai Seas, sediment transport of particles with different sizes in the computational area is given. It is concluded that tidal currents play an...-Based on a two-dimensional numerical M2 tidal model of the Huanghai and Bohai Seas, sediment transport of particles with different sizes in the computational area is given. It is concluded that tidal currents play an important role in sediment transport and deposition in the Huanghai and Bohai Seas.展开更多
The Bohai Sea is a semi-enclosed marginal sea in the North West Pacific. Meiofauna samples were collected from 22 stations in the Bohai Sea to document the spatial distribution, structure, and diversity of the meiofau...The Bohai Sea is a semi-enclosed marginal sea in the North West Pacific. Meiofauna samples were collected from 22 stations in the Bohai Sea to document the spatial distribution, structure, and diversity of the meiofaunal community and investigate the major factors influencing the community features. A total of 20 higher taxa of meiofauna were identified. The dominant group was Nematoda, accounting for 90.8% of the total meiofaunal abundance on average, followed by Copepoda, Bivalvia, Polychaeta, Kinorhyncha, and Ostracoda. Meiofaunal abundance ranged from 121 ± 89 ind(10 cm2)-1 to 3042 ± 1054 ind(10 cm2)-1. Diversity indices also varied among different stations, with a Margalef's richness index(d) of 1.1–3.1, Shannon-Wiener diversity index(H′) of 0.7–1.8, and Pielou's evenness index(J′) of 0.4– 0.8. Meiofaunal abundance and diversity indices were significantly lower in the areas of Bohai Bay and adjacent to Laizhou Bay. The correlation analysis showed that meiofaunal abundance and diversity indices are closely linked to variations in sediment silt-clay content, medium grain size(MDΦ), and chlorophyll-a concentrations. The ecological quality status of most stations can be ranked from poor to moderate based on meiofaunal richness. According to the value of nematode to copepod ratio(Ne:Co ratio), most stations are uncontaminated, except seven stations are slightly or moderately contaminated. Both meiofaunal richness and Ne:Co ratio indicate the poor ecological quality of three stations adjacent to Laizhou Bay. The efficiency of the meiofauna communities as environmental indicators will be tested in a greater area in the future studies.展开更多
On the basis of a three-dimensional weakly nonliear theory of Lagrangian residual current in the Baroclinic shallow seas, a diagnostic numerical calculation of wind-driven, thermohaline and tide-induced Lagrangian res...On the basis of a three-dimensional weakly nonliear theory of Lagrangian residual current in the Baroclinic shallow seas, a diagnostic numerical calculation of wind-driven, thermohaline and tide-induced Lagrangian residual current in the Bohai Sea is made. The model involves the Richardson number in the eddy viscosity coefficient, wind, thcrmolialine and tidal effects in the focing terms. The runoff of the Huanghe River and a part of the Huanghai Warm Water coming from the Huanghai Sea through the Bohai Sea Strait is also considered. The velocity-splitting method is adopted. The wind-driven circu lation, thermohaline circulation and the tide-induced Lagrangian residual circulation are also obtained individually and analysed. The dynamics of the three main eddies in the Lagrangian mean circulation is discussed. Finally, the numerical result is partly verified with the observed data.展开更多
-On the basis of the data obtained from the surveys in the Bohai Sea during 1982-1983, this paper analysed and discussed the distribution and seasonal variation of primary productivity in the Bohai Sea, and the correl...-On the basis of the data obtained from the surveys in the Bohai Sea during 1982-1983, this paper analysed and discussed the distribution and seasonal variation of primary productivity in the Bohai Sea, and the correlations between the primary productivity and environmental factors. The organic carbon production and prospect of fishery production in the waters of this sea are estimated. It is shown that, there exists production patential in the Bohai Sea, the primary production is 112 gC/ (m2 ?a)the production of organic carbon being 10 million ton per year, the fishery yields 1 million ton and the maximum catch of sea products 0. 5 million ton. The results of the investigation can serve as the basic data for the exploitation, utilization and management of the fishery resources in the Bohai Sea.展开更多
Oil spilled on the sea ice surface in the Bohai Sea of China is studied through the field measurements of the reflectance of a simulated sea ice-oil film mixed pixel. The reflection characteristics of sea ice and oil ...Oil spilled on the sea ice surface in the Bohai Sea of China is studied through the field measurements of the reflectance of a simulated sea ice-oil film mixed pixel. The reflection characteristics of sea ice and oil film are also analyzed. It is found that the mixed pixel of sea ice and oil film is a linear mixed pixel. The means of extracting sea ice pixels containing oil film is presented using a double-band ratio oil-film sea-ice index(DROSI) and a normalized difference oil-film sea-ice index(NDOSI) through the analysis of the reflectance curves of the sea iceoil film pixel for different ratios of oil film. The area proportion of the oil film in the sea ice-oil film pixel can be accurately estimated by the average reflectance of the band of 1 610–1 630 nm, and the volume of the spilled oil can be further estimated. The method of the sea ice-oil film pixel extraction and the models to estimate the proportion of oil film area in the sea ice-oil film pixel can be applied to the oil spill monitoring of the ice-covered area in the Bohai Sea using multispectral or hyperspectral remote sensing images in the shortwave infrared band(1 500–1 780 nm).展开更多
In this paper, on the basis of the heat conduction equation without consideration of the advection and turbulence effects, one-dimensional model for describing surface sea temperature ( T1), bottom sea temperature ( T...In this paper, on the basis of the heat conduction equation without consideration of the advection and turbulence effects, one-dimensional model for describing surface sea temperature ( T1), bottom sea temperature ( Tt ) and the thickness of the upper homogeneous layer ( h ) is developed in terms of the dimensionless temperature θT and depth η and self-simulation function θT - f(η) of vertical temperature profile by means of historical temperature data.The results of trial prediction with our one-dimensional model on T, Th, h , the thickness and gradient of thermocline are satisfactory to some extent.展开更多
During June 1997 cruise by R/V Science No.l, observations on temporal and spatialvariations of the size-fractionated phytoplankton standing stock and primary production were carried out in the Bohai Sea. The size-frac...During June 1997 cruise by R/V Science No.l, observations on temporal and spatialvariations of the size-fractionated phytoplankton standing stock and primary production were carried out in the Bohai Sea. The size-fractionated chlorophyll a (Chl a) and primary production, photosynthet-ically available radiation (PAR), as well as the related physico-oceanographic and zooplanktonic parameters were measured at five time-series observation stations representing sub-areas of the sea. Results obtained show that there were the marked features of spatial zonation of Chl a and primary production in the Bohai Sea. The values in the Laizhou Bay, the Liaodong Gulf and the Bohai Gulf were high and showed close relation with tidal fluctuations, i.e. high Chi a concentration occurred during high tide in the Laizhou Bay, and during low tide in the Liaodong Gulf and the Bohai Gulf. In the strait and the central region of the Bohai Sea, the values were relatively low and no relationship with tidal fluctuation could be found. Chlorophyll a concentration vertically decreased from surface to bottom in the Liaodong Gulf and the Bohai Gulf, while it increased in the Laizhou Bay, the strait and the central region of the Bohai Sea, and the highest value was encountered at the bottom. Size-fractionation results showed that nano - combining pico -plankton ( < 20 μm) predominated in phytoplankton communities of the Bohai Sea during late spring. The average contribution to total Chl a in each station ranged 76% -95 % (mean is 87 %). The contribution of net (> 20 μm), nano - (2- 20 fan) and picoplankton (< 2 μm) was 13% , 63% and 24% to total production, and 9% , 53% and 38% to total Chl a, respectively. It proved the importance of nano - and pico -plankton in phytoplankton communities in the Bohai Sea e-cosystems. In this paper the factors, such as light intensity and zooplankton grazing pressure, governing standing stock and production of phytoplankton in the Bohai Sea were also discussed.展开更多
Investigations of sediment-water fluxes of nutrients in the Bohai Sea were carried out in September - October 1998 and April - May 1999. The exchange fluxes of nutrients between sediment and sea water were determined ...Investigations of sediment-water fluxes of nutrients in the Bohai Sea were carried out in September - October 1998 and April - May 1999. The exchange fluxes of nutrients between sediment and sea water were determined by incubating the core-top sediments with overlying water aerated with air. The benthic fluxes of NO3- , NO2- , NH4+ , DIN, DON and TON in the first cruise and the flux-es of NO3 , NO2- , NH4+ , DIN, DON, TDN, PO43- , DOP and TDP in the second cruise were measured. The exchange fluxes of nutrients in fall were higher than in spring. The benthic nutrient fluxes represented 15% -55% of nutrient budgets in the Bohai Sea.展开更多
Besides seasonal variation, instantaneous variation of thermal layer will occur under the effects of tide, tidal current and wind disturbance. In this study the numerical simulation has been first carried out on fluct...Besides seasonal variation, instantaneous variation of thermal layer will occur under the effects of tide, tidal current and wind disturbance. In this study the numerical simulation has been first carried out on fluctuation and undulation of thermal layer under influence of tide (simultaneous input of 8 tidal components). The study reveals the geographic distribution of thermal layer fluctuation in the entire study region and temporal and spatial variations of the undulation in tidal period superposing on the fluctuation. Especially, the wave with large amplitude simulated is consistent with observation in the channal and the sea areas with a convex coastline and complex variation of depth, internal relations of tide, tidal current, residual current as well as the factors such as geography, and the fluctuation of thermal layer is induced by residual current due to unsymmetry which occurs as a result of the tidal movement in lower layer influenced by friction and geography, meanwhile, analysis indicates that the fluctuation of thermal layer and tidal oscillation are different undulations in character.展开更多
In this paper, the numerical modelling of the tidal level and current in the Bohai Sea was carried out with ADI method, by taking the sum of four main tidal components M2,S2K2,O1 as the open boundary condition. The ca...In this paper, the numerical modelling of the tidal level and current in the Bohai Sea was carried out with ADI method, by taking the sum of four main tidal components M2,S2K2,O1 as the open boundary condition. The calculated values were consistent with the predicted ones (the observed values in the case of calm) in the Tidal Table. On the basis of the modelling of the tide, the sea level and current fields under the effects of strong wind were simulated. The calculated results were also quite satisfactory.展开更多
The biomasses of fishes at the bottom layer of the Bohai Sea are extimated by analysing the data on samples (447 hauls,more than 0.2 million in number or 20 t in weight of fishes) collected monthly by our institute fr...The biomasses of fishes at the bottom layer of the Bohai Sea are extimated by analysing the data on samples (447 hauls,more than 0.2 million in number or 20 t in weight of fishes) collected monthly by our institute from April, 1982 to May, 1983 by a pair of bottom trawls through the Bohai Sea. The exploitation problems are also discussed in this paper.展开更多
-Some numerical experiments have been developed to explain dynamically the mechanism of the formation of the wintertime circulation in the Northern Huanghai Sea and the Bohai Sea. From the results of the numerical exp...-Some numerical experiments have been developed to explain dynamically the mechanism of the formation of the wintertime circulation in the Northern Huanghai Sea and the Bohai Sea. From the results of the numerical experiments with Coriolis parameter having positive and negative values respectively, it is found that the current pattern characterized by flowing into the Bohai Sea in the northern part of the Bohai Straits and flowing out of the Bohai Sea in the southern part of the Bohai Straits is controlled basically by the bottom topography with 'the deepness on the northern side and shallowness on the southern side'in the Bohai Straits, and is not related to Coriolis parameter having positive and negative values. It also shows that the Huanghai Warm Current regarded as the inllow condition passing through the in-ports at the water boundary of the numerical experiments only influences the region near the water boundary and the eastern region of the Northern Huanghai Sea. In addition, the mechanism of the formation of several mesoscale eddies and the influence of the bottom topography on the wintertime circulation in the basin have been discussed.展开更多
基金State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University of China under contract No.2009-KF-08the Key Project of the National Natural Science Foundation of China under contract No.ID:40335048+1 种基金the National Science and Technology Plans to Support Major Projects Subject under contract No.ID: 2006BAB03A03the National ‘863’ Key Project of China under contract No.ID: 2006AA100206
文摘The research on sea ice resources is the academic base of sea ice exploitation in the Bohai Sea. According to the ice-water spectrum differences and the correlation between ice thickness and albedo, this paper comes up with a sea ice thickness inversion model based on the NOAA/AVHRR data. And then a sea ice resources quantity (SIQ) time series of Bohai Sea is established from 1987 to 2009. The results indicate that the average error of inversion sea ice thickness is below 30%. The maximum sea ice resources quantity is about 6×109 m3 and the minimum is 1.3×109 m3. And a preliminary analysis has been made on the errors of the estimate of sea ice resources quantity (SIQ).
基金This work was supported by the National Natural Science Foundation of China under contract Nos 49976007 and 59739170Universi
文摘The ice conditions in the Bohai Sea and the northern Huanghai Sea greatly change from year to year with winter climate. Ice only covers below 15% of the the waters during the wannest win-ter, while it covers more than 80% during the coldest winter. Ice observation and data acquisition are outlined in the paper. The ice-covered area, the position of ice edge and the ice grades give indication of the ice conditions. The local climate of the waters can be expressed by using the air temperature of the stations of Dalian and Yingkou. The variation of the ice condition indexes with the monthly mean air temperature at Dalian from 1952 to 2000 is shown, as well. The local climate and ice conditions in the waters are affected by many factors,such as, evolution of the general atmospheric circulation and the solar activity. The delayed correlation between the ice conditions and lots of the affecting factors is analysed in the paper. The ice conditions are continuously mild since the 1990s, that is relative to the tendency of the global warming. The ice condition variation of the Bohai Sea is related to the El Nino event and the sunspot period. The seasonal evolution of the ice conditions is also described in the paper.
文摘A hierarchical diversity index—taxonomic distinctness index Δ +, which was first defined by Warwick and Clark in 1998, was employed to evaluate the pollution status of the Bohai Sea with freeliving marine nematodes. The result showed that the Bohai Bay and other coastal sampling sites might be affected by oil and gas production and other anthropogenic influences. In other words,anthropogenic disturbance was affecting this component of the benthos in these locations. And most offshore sampling sites in the middle of the Bohai Sea were clear and unpolluted.
基金The project was supported by Darwin Initiative Project from Department of Environment. UK National Natural Science Foundatio
文摘A grid of 22 stations, giving a broad geographic coverage of the Bohai Sea and the Bohai Strait was selected. Undisturbed sediments were collected from sampling stations during cruises in June 1997, in September/October 1998 and again in April/May 1999. Based on the results of Juario (1975), the average biomass, 0.404 g/(m2a) of meiofauna (including nematode, harpacticoida, bivalve larvae, polycheata and kinorhyncha) in the Bohai Sea is given and accounts for 4.5 percent of the macrofauna in the Bohai Sea. The horizontal distribution of the biomass of meiofauna showed that it was higher at the stations of middle east part of the Bohai Sea and the strait in 1998 and 1999 cruises and it decreased at the stations near to the strait mouth and increased at Station B1 in 1999 cruise. The annual average production in the Bohai Sea is 3.636 g/m2 calculated in term of the formula P = 9B. Compared with the biomass of other sea areas in the world, the biomass of the Bohai Sea is similar but slightly lower. The individual average dry weight of nematodes given by different authors is analyzed.
基金The Hi-tech Research and Development Program(863 Program) of China under contract No2007AA09Z117comprehensive Survey and Assessment of China’s Coastal Sea Program(China ‘908’ Project) under contract No908-01-ST02China "973" Program under contract No 2005CB422302
文摘Based on the comprehensive collection of the field observed salinity of the Bohai Sea (BHS) and the northern Huanghai Sea (NHS) from the 1950s to the present, the patterns of 10-years-averaged salinity at the different layers in the recent five decades (the 1950s, the 1960s, the 1970s, the 1980s and the 1990s) are obtained by the spatial-temporal interpolation technique with the scrupulous data quality control in this study. Then, by combining the spatial-temporal interpolation technique with successive correction method, the annual distributions of salinity both in the BHS and in the NHS are obtained as well. The data analyses indicate that the overall salinity in the BHS and the NHS increases from the 1960s till the present, with the increase of annual mean salinity of 0.04 psu from the 1950s, and the maximum increase rate of salinity is about 0.14 psu/a in the Bohai Bay. The high salinity tongue extended significantly from the NHS into the BHS. The intensified eastern wind field is related to the western intrusion of the NHS warm current, which probably leads to the moving forward of the high salinity water mass into the BHS. However, it is rather different from the salinity distribution characteristics between the 1950s and the 1960s. The extensive precipitation in the 1960s could lead to an increase in the discharge of the Huanghe River, which might result in the decrease of salinity in the BHS. But the salinity isoline of 32 in the NHS still extended significantly into the BHS in the 1960s. Since the 1980s, the patterns of salinity distribution have changed thoroughly. The salinity in the central area of the BHS was low, while the salinity in the Bohai Bay and the Liaodong Bay was higher than the other regions with its horizontal salinity gradient decreasing in the 1980s. The Empirical Orthogonal Function Analysis (EOF) is also conducted to study the interannual salinity variability of the BHS and the NHS. The correlation coefficient between the time coefficient series of the main mode and the Huanghe River discharge can reach-64.57%. It can be concluded that salinity variation of the BHS and the NHS has strong negative correlation with the Huanghe River discharge.
基金This subject is aided financially by Chinese National Natural Science Foundation.
文摘On the basis of perennial monthly mean temperature and salinity data, the classification of monthly water masses at the surface and the bottom in the Bohai Sea, the Huanghai Sea and the East China Sea, has been made by using the method of fuzzy cluster from the modified characteristic of water masses in the shallow water area. In this paper, the basic features, growth and decline patterns of water masses in relation to fishing grounds in the whole shelves of the Bohai Sea, the Huanghai Sea and the East China Sea are discussed with emphasis.
基金Supported by the National Natural Science Foundation of China(No.41776012)the Key R&D Project of Zhejiang Province(No.2020C03012)+4 种基金the Shandong Provincial Natural Science Foundation(No.ZR2020MD059)the Key R&D Project of Guangdong Province(No.2020B1111030002)the Major Science and Technology Project of Sanya YZBSTC(No.SKJC-KJ-2019KY03)the National Key R&D Program of China(No.2019YFD0901305)the Marine Science and Technology Project of North China Sea Bureau in 2020:Tempo-Spatial Distribution and Its Mechanisms of the Bottom Oxygen-Poor Zones in the Bohai Sea(No.202001)。
文摘Deoxygenation has frequently appeared in coastal ecosystems over the past century due to the joint infl uence of increasing anthropogenically induced nutrient inputs and global warming.The semi-enclosed Bohai Sea is a typical system that is prone to deoxygenation,with regular hypoxia events consistently recorded in recent decades.Based on in-situ observation data collected in large-scale voyage surveys in the Bohai Sea during 2008-2017,the seasonal variability in dissolved oxygen(DO)and its controlling mechanisms were studied.The results indicated that in spring and autumn,the DO distributions exhibited similar spatial patterns in the surface and bottom layers,while in summer,its spatial distribution was characterized by large-scale oxygen-poor zones distributed off the Qinhuangdao Coast and the central southern Bohai Sea in the bottom layer.The controlling mechanisms of the DO distribution varied from season to season.Spring and autumn DO distributions were dominated by the seawater temperature.Under the combined eff ects of stratifi cation and decomposition,the summer bottom DO exhibited dual-core distribution.On the one hand,stratifi cation could greatly impede vertical mixing,resulting in reduced bottom DO replenishment.On the other hand,the increased bottom organic matter intensifi ed the decomposition processes,inducing massive DO consumption and elevated dissolved inorganic nitrogen concentrations.In addition,the stronger stratifi cation might be the reason for the more severe deoxygenation in the southern oxygen-poor zones in summer.Our study provides guidance for an in-depth understanding of the DO seasonality in the Bohai Sea and the mechanisms that modulate it and for the improvement of hypoxia forecasts in ocean models.
文摘The carbon cycle of lower trophic level in the Bohai Sea is studied with a three-dimensional biological and physical coupled model. The influences of the processes (including horizontal advection, river nutrient load, active transport etc. ) on the phytoplankton biomass and its evolution are estimated. The Bohai Sea is a weak sink of the CO2 in the atmosphere. During the cycle, 13.7% of the gross production of the phytoplankton enter the higher trophic level and 76.8 % of it are consumed by the respiration itself. The nutrient reproduction comes mainly from the internal biogeochemical loop and the rem-ineralization is an important mechanism of the nutrient transfer from organic form to inorganic. Horizontal advection decreases the total biomass and the eutrophication in some sea areas. Change in the nutrient load of a river can only adjust the local system near its estuary. Controlling the input of the nutrient, which limits the alga growth, can be very useful in lessening the phytoplankton biomass.
文摘-Based on a two-dimensional numerical M2 tidal model of the Huanghai and Bohai Seas, sediment transport of particles with different sizes in the computational area is given. It is concluded that tidal currents play an important role in sediment transport and deposition in the Huanghai and Bohai Seas.
基金supported by the Fundamental Research Funds for the Central Universities (No. 201964024)the National Natural Science Foundation of China (No. 41976131 and No. 40906063)。
文摘The Bohai Sea is a semi-enclosed marginal sea in the North West Pacific. Meiofauna samples were collected from 22 stations in the Bohai Sea to document the spatial distribution, structure, and diversity of the meiofaunal community and investigate the major factors influencing the community features. A total of 20 higher taxa of meiofauna were identified. The dominant group was Nematoda, accounting for 90.8% of the total meiofaunal abundance on average, followed by Copepoda, Bivalvia, Polychaeta, Kinorhyncha, and Ostracoda. Meiofaunal abundance ranged from 121 ± 89 ind(10 cm2)-1 to 3042 ± 1054 ind(10 cm2)-1. Diversity indices also varied among different stations, with a Margalef's richness index(d) of 1.1–3.1, Shannon-Wiener diversity index(H′) of 0.7–1.8, and Pielou's evenness index(J′) of 0.4– 0.8. Meiofaunal abundance and diversity indices were significantly lower in the areas of Bohai Bay and adjacent to Laizhou Bay. The correlation analysis showed that meiofaunal abundance and diversity indices are closely linked to variations in sediment silt-clay content, medium grain size(MDΦ), and chlorophyll-a concentrations. The ecological quality status of most stations can be ranked from poor to moderate based on meiofaunal richness. According to the value of nematode to copepod ratio(Ne:Co ratio), most stations are uncontaminated, except seven stations are slightly or moderately contaminated. Both meiofaunal richness and Ne:Co ratio indicate the poor ecological quality of three stations adjacent to Laizhou Bay. The efficiency of the meiofauna communities as environmental indicators will be tested in a greater area in the future studies.
基金Project supported by the National Natural Science Foundation of China
文摘On the basis of a three-dimensional weakly nonliear theory of Lagrangian residual current in the Baroclinic shallow seas, a diagnostic numerical calculation of wind-driven, thermohaline and tide-induced Lagrangian residual current in the Bohai Sea is made. The model involves the Richardson number in the eddy viscosity coefficient, wind, thcrmolialine and tidal effects in the focing terms. The runoff of the Huanghe River and a part of the Huanghai Warm Water coming from the Huanghai Sea through the Bohai Sea Strait is also considered. The velocity-splitting method is adopted. The wind-driven circu lation, thermohaline circulation and the tide-induced Lagrangian residual circulation are also obtained individually and analysed. The dynamics of the three main eddies in the Lagrangian mean circulation is discussed. Finally, the numerical result is partly verified with the observed data.
文摘-On the basis of the data obtained from the surveys in the Bohai Sea during 1982-1983, this paper analysed and discussed the distribution and seasonal variation of primary productivity in the Bohai Sea, and the correlations between the primary productivity and environmental factors. The organic carbon production and prospect of fishery production in the waters of this sea are estimated. It is shown that, there exists production patential in the Bohai Sea, the primary production is 112 gC/ (m2 ?a)the production of organic carbon being 10 million ton per year, the fishery yields 1 million ton and the maximum catch of sea products 0. 5 million ton. The results of the investigation can serve as the basic data for the exploitation, utilization and management of the fishery resources in the Bohai Sea.
基金The National High Technology Research and Development Program(863 Program)of China under contract No.2011AA100505the Projects of the State Key Laboratory of Earth Surface Progresses and Resource Ecology,Beijing Normal University of China under contract No.2010-KF-08
文摘Oil spilled on the sea ice surface in the Bohai Sea of China is studied through the field measurements of the reflectance of a simulated sea ice-oil film mixed pixel. The reflection characteristics of sea ice and oil film are also analyzed. It is found that the mixed pixel of sea ice and oil film is a linear mixed pixel. The means of extracting sea ice pixels containing oil film is presented using a double-band ratio oil-film sea-ice index(DROSI) and a normalized difference oil-film sea-ice index(NDOSI) through the analysis of the reflectance curves of the sea iceoil film pixel for different ratios of oil film. The area proportion of the oil film in the sea ice-oil film pixel can be accurately estimated by the average reflectance of the band of 1 610–1 630 nm, and the volume of the spilled oil can be further estimated. The method of the sea ice-oil film pixel extraction and the models to estimate the proportion of oil film area in the sea ice-oil film pixel can be applied to the oil spill monitoring of the ice-covered area in the Bohai Sea using multispectral or hyperspectral remote sensing images in the shortwave infrared band(1 500–1 780 nm).
文摘In this paper, on the basis of the heat conduction equation without consideration of the advection and turbulence effects, one-dimensional model for describing surface sea temperature ( T1), bottom sea temperature ( Tt ) and the thickness of the upper homogeneous layer ( h ) is developed in terms of the dimensionless temperature θT and depth η and self-simulation function θT - f(η) of vertical temperature profile by means of historical temperature data.The results of trial prediction with our one-dimensional model on T, Th, h , the thickness and gradient of thermocline are satisfactory to some extent.
基金This study was supported by the National Natural Science Foundation of China (NSFC) under contract No. 49790010.
文摘During June 1997 cruise by R/V Science No.l, observations on temporal and spatialvariations of the size-fractionated phytoplankton standing stock and primary production were carried out in the Bohai Sea. The size-fractionated chlorophyll a (Chl a) and primary production, photosynthet-ically available radiation (PAR), as well as the related physico-oceanographic and zooplanktonic parameters were measured at five time-series observation stations representing sub-areas of the sea. Results obtained show that there were the marked features of spatial zonation of Chl a and primary production in the Bohai Sea. The values in the Laizhou Bay, the Liaodong Gulf and the Bohai Gulf were high and showed close relation with tidal fluctuations, i.e. high Chi a concentration occurred during high tide in the Laizhou Bay, and during low tide in the Liaodong Gulf and the Bohai Gulf. In the strait and the central region of the Bohai Sea, the values were relatively low and no relationship with tidal fluctuation could be found. Chlorophyll a concentration vertically decreased from surface to bottom in the Liaodong Gulf and the Bohai Gulf, while it increased in the Laizhou Bay, the strait and the central region of the Bohai Sea, and the highest value was encountered at the bottom. Size-fractionation results showed that nano - combining pico -plankton ( < 20 μm) predominated in phytoplankton communities of the Bohai Sea during late spring. The average contribution to total Chl a in each station ranged 76% -95 % (mean is 87 %). The contribution of net (> 20 μm), nano - (2- 20 fan) and picoplankton (< 2 μm) was 13% , 63% and 24% to total production, and 9% , 53% and 38% to total Chl a, respectively. It proved the importance of nano - and pico -plankton in phytoplankton communities in the Bohai Sea e-cosystems. In this paper the factors, such as light intensity and zooplankton grazing pressure, governing standing stock and production of phytoplankton in the Bohai Sea were also discussed.
基金This study was supported by the special Funds from National Key Basic Research Program of China under contract No. G1999043705
文摘Investigations of sediment-water fluxes of nutrients in the Bohai Sea were carried out in September - October 1998 and April - May 1999. The exchange fluxes of nutrients between sediment and sea water were determined by incubating the core-top sediments with overlying water aerated with air. The benthic fluxes of NO3- , NO2- , NH4+ , DIN, DON and TON in the first cruise and the flux-es of NO3 , NO2- , NH4+ , DIN, DON, TDN, PO43- , DOP and TDP in the second cruise were measured. The exchange fluxes of nutrients in fall were higher than in spring. The benthic nutrient fluxes represented 15% -55% of nutrient budgets in the Bohai Sea.
文摘Besides seasonal variation, instantaneous variation of thermal layer will occur under the effects of tide, tidal current and wind disturbance. In this study the numerical simulation has been first carried out on fluctuation and undulation of thermal layer under influence of tide (simultaneous input of 8 tidal components). The study reveals the geographic distribution of thermal layer fluctuation in the entire study region and temporal and spatial variations of the undulation in tidal period superposing on the fluctuation. Especially, the wave with large amplitude simulated is consistent with observation in the channal and the sea areas with a convex coastline and complex variation of depth, internal relations of tide, tidal current, residual current as well as the factors such as geography, and the fluctuation of thermal layer is induced by residual current due to unsymmetry which occurs as a result of the tidal movement in lower layer influenced by friction and geography, meanwhile, analysis indicates that the fluctuation of thermal layer and tidal oscillation are different undulations in character.
文摘In this paper, the numerical modelling of the tidal level and current in the Bohai Sea was carried out with ADI method, by taking the sum of four main tidal components M2,S2K2,O1 as the open boundary condition. The calculated values were consistent with the predicted ones (the observed values in the case of calm) in the Tidal Table. On the basis of the modelling of the tide, the sea level and current fields under the effects of strong wind were simulated. The calculated results were also quite satisfactory.
文摘The biomasses of fishes at the bottom layer of the Bohai Sea are extimated by analysing the data on samples (447 hauls,more than 0.2 million in number or 20 t in weight of fishes) collected monthly by our institute from April, 1982 to May, 1983 by a pair of bottom trawls through the Bohai Sea. The exploitation problems are also discussed in this paper.
文摘-Some numerical experiments have been developed to explain dynamically the mechanism of the formation of the wintertime circulation in the Northern Huanghai Sea and the Bohai Sea. From the results of the numerical experiments with Coriolis parameter having positive and negative values respectively, it is found that the current pattern characterized by flowing into the Bohai Sea in the northern part of the Bohai Straits and flowing out of the Bohai Sea in the southern part of the Bohai Straits is controlled basically by the bottom topography with 'the deepness on the northern side and shallowness on the southern side'in the Bohai Straits, and is not related to Coriolis parameter having positive and negative values. It also shows that the Huanghai Warm Current regarded as the inllow condition passing through the in-ports at the water boundary of the numerical experiments only influences the region near the water boundary and the eastern region of the Northern Huanghai Sea. In addition, the mechanism of the formation of several mesoscale eddies and the influence of the bottom topography on the wintertime circulation in the basin have been discussed.