2012 Vol. 34, No. 3
Display Method:
2012, 34(3): 1-10.
Abstract:
Based on the observed water level and current data during the winter of 2008 at four bottom-moorings near Nanji Island, Zhejiang Province, the characteristics of tide and tidal current are investigated with spectral and harmonic analysis. Spectral analysis of the water level shows that the semi-diurnal tides are the most significant constituents, followed by diurnal tides, shallow water tides at inshore area are significant than that in offshore. Harmonic analysis of the water level shows that the tide is regular semi-diurnal tide, the average tidal range is over 3 m and the potential maximum tidal range is greater than 6m at inshore area. The tide has significant low tide daily inequality and tropical tide characteristics. Spectral analysis of the current shows that the semi-diurnal tidal currents are the most significant constituents, followed by diurnal tidal currents which are much weaker than the former, shallow water tidal current at inshore area is much more significant than that in offshore. Harmonic analysis of the current shows that the tidal current is regular semi-diurnal tidal current, the most significant semi-diurnal tidal current constituent is M2, with its maximum speed of 0.32-0.48 m/s,the most significant diurnal tidal current constituent is K1, with its maximum speed less than 0.06 m/s. The M2 tidal current rotates counter-clockwise, with increasing of its ellipticity as approaching to the sea floor. The maximum speed of M2 tidal current occurs at middle and upper layers, decreases towards the surface and the sea floor. The direction of the maximum tidal current of M2 does not vary significant with depth, except that the direction deviates slightly to the left near the sea floor. The timing of the maximum current advances when approaching to the sea floor, with about 30 minutes ahead at the bottom layer than the above layer. The semidiurnal tidal current is barotropic dominate with vertical homogeneous, while the diurnal tidal current shows a baroclinic property with a strong vertical variation.
Based on the observed water level and current data during the winter of 2008 at four bottom-moorings near Nanji Island, Zhejiang Province, the characteristics of tide and tidal current are investigated with spectral and harmonic analysis. Spectral analysis of the water level shows that the semi-diurnal tides are the most significant constituents, followed by diurnal tides, shallow water tides at inshore area are significant than that in offshore. Harmonic analysis of the water level shows that the tide is regular semi-diurnal tide, the average tidal range is over 3 m and the potential maximum tidal range is greater than 6m at inshore area. The tide has significant low tide daily inequality and tropical tide characteristics. Spectral analysis of the current shows that the semi-diurnal tidal currents are the most significant constituents, followed by diurnal tidal currents which are much weaker than the former, shallow water tidal current at inshore area is much more significant than that in offshore. Harmonic analysis of the current shows that the tidal current is regular semi-diurnal tidal current, the most significant semi-diurnal tidal current constituent is M2, with its maximum speed of 0.32-0.48 m/s,the most significant diurnal tidal current constituent is K1, with its maximum speed less than 0.06 m/s. The M2 tidal current rotates counter-clockwise, with increasing of its ellipticity as approaching to the sea floor. The maximum speed of M2 tidal current occurs at middle and upper layers, decreases towards the surface and the sea floor. The direction of the maximum tidal current of M2 does not vary significant with depth, except that the direction deviates slightly to the left near the sea floor. The timing of the maximum current advances when approaching to the sea floor, with about 30 minutes ahead at the bottom layer than the above layer. The semidiurnal tidal current is barotropic dominate with vertical homogeneous, while the diurnal tidal current shows a baroclinic property with a strong vertical variation.
2012, 34(3): 11-18.
Abstract:
This paper describes a coupling model that simulates tsunami and the astronomical tide in the South China Sea. The coupling model is based on the tsunami model COMCOT and the global tide model TPXO7.1, using a 3-layer nested grid system. Tide-tsunami interactions are investigated in Shenzhen Waters. The computed results of tide simulations are in good agreements with observations with the average errors for the high and low tide level less than 15 cm and 20 cm. Based on tide simulations, tsunamis induced by the hypothetical earthquakes of the magnitude 8.0 and 9.0 in the Manila Trench are adopted as scenarios to simulate the tsunamis and tides interaction. The computed results show that, the tsunami wave height for 9.0Mw earthquake is about 140-150 cm outside Shenzhen Waters; and if the first tsunami wave is a positive wave which occurs at high tide level, the tsunami tide level will be extreme high, while a negative wave occurs at low tide level, the tsunami tide level will be extreme low. Compared with the coupling results, the wave height of tsunami calculated separately is about 25.0 cm higher, and the difference of tsunami arrival time is less than 6.0 mins.
This paper describes a coupling model that simulates tsunami and the astronomical tide in the South China Sea. The coupling model is based on the tsunami model COMCOT and the global tide model TPXO7.1, using a 3-layer nested grid system. Tide-tsunami interactions are investigated in Shenzhen Waters. The computed results of tide simulations are in good agreements with observations with the average errors for the high and low tide level less than 15 cm and 20 cm. Based on tide simulations, tsunamis induced by the hypothetical earthquakes of the magnitude 8.0 and 9.0 in the Manila Trench are adopted as scenarios to simulate the tsunamis and tides interaction. The computed results show that, the tsunami wave height for 9.0Mw earthquake is about 140-150 cm outside Shenzhen Waters; and if the first tsunami wave is a positive wave which occurs at high tide level, the tsunami tide level will be extreme high, while a negative wave occurs at low tide level, the tsunami tide level will be extreme low. Compared with the coupling results, the wave height of tsunami calculated separately is about 25.0 cm higher, and the difference of tsunami arrival time is less than 6.0 mins.
2012, 34(3): 19-26.
Abstract:
A general ocean carbon cycle model which is based on the ocean circulation model of POP and the biogeochemical model of OCMIP-2, is employed to simulate the global ocean carbon cycle. After spinning-up for 3 100 years, the model reaches the pre-industrial stable state, under the pre-industrial condition that the CO2 concentration in atmosphere is 283×10-6. Then the model is forced by the observed historical atmosphere CO2 concentration. The distributions of the simulated dissolved inorganic carbon and alkalinity are consistent with the available observations. The model results show that in the mid-and high-latitude of the northern hemisphere and the mid-latitude of the southern hemisphere, ocean is the sink of CO2, while in the equatorial area and south of 50°S, ocean is the source of CO2. The global air-sea flux of CO2 is 1.38 Pg/a in 1980s, while it reaches 1.55 Pg/a in 1990s. In the north Atlantic, the anthropogenic CO2 concentration is the highest in the global ocean, and the anthropogenic CO2 can reach the ocean deep layer and can be transported to 30°N, while in the vicinity of the Antarctic, the concentration is much lower. In the mid-latitude area, the anthropogenic carbon is trapped in the upper layer shallower than 1 000 m mainly by the thermocline and vertical mixing.
A general ocean carbon cycle model which is based on the ocean circulation model of POP and the biogeochemical model of OCMIP-2, is employed to simulate the global ocean carbon cycle. After spinning-up for 3 100 years, the model reaches the pre-industrial stable state, under the pre-industrial condition that the CO2 concentration in atmosphere is 283×10-6. Then the model is forced by the observed historical atmosphere CO2 concentration. The distributions of the simulated dissolved inorganic carbon and alkalinity are consistent with the available observations. The model results show that in the mid-and high-latitude of the northern hemisphere and the mid-latitude of the southern hemisphere, ocean is the sink of CO2, while in the equatorial area and south of 50°S, ocean is the source of CO2. The global air-sea flux of CO2 is 1.38 Pg/a in 1980s, while it reaches 1.55 Pg/a in 1990s. In the north Atlantic, the anthropogenic CO2 concentration is the highest in the global ocean, and the anthropogenic CO2 can reach the ocean deep layer and can be transported to 30°N, while in the vicinity of the Antarctic, the concentration is much lower. In the mid-latitude area, the anthropogenic carbon is trapped in the upper layer shallower than 1 000 m mainly by the thermocline and vertical mixing.
2012, 34(3): 27-40.
Abstract:
The significant climate characteristic in the South China Sea (SCS) during winter monsoon is that northeast monsoon is the prevailing wind and cold surges frequently occur.The features of sea-air heat flux and budget during the winter monsoon,especially during the cold surges,were studied,based on the data collected from the sea-air flux experiment in Yongxing Island,SCS,from October 2008 to April 2009.The results showed that:the sensible heat (SH) flux slightly increased during the prophase of winter monsoon with the increase of temperature difference between air and sea s compared to that during summer (southwest) monsoon.The average latent heat (LH) flux during winter monsoon was almost equal to that during the summer (southwest) monsoon.The total solar radiation decreased significantly,and the long wave radiation of the atmosphere also decreased,as a result,the net heat budget of the sea became negative value,which caused the sea surface temperature (SST) dropping after autumn.The SH fluxes during the cold surges were higher than the average flux during the winter monsoon,and before January,most of the LH fluxes during the cold surge were also higher than the average flux of winter monsoon.Due to the increase of SH flux and the decrease of solar radiation,the net heat budgets of the sea,during the cold surges before January,generally turned into high negative value,which caused the sea losing more heat than during winter monsoon,and even more than the average heat loss of the typhoons in 2008.At the end of winter monsoon,while the total solar radiation increased,the net heat budget of the sea turned to positive,so the SST increased gradually.Among all seasons,the SH flux in winter monsoon was the largest,the second largest in autumn,and the minimum in spring.The LH flux was the largest during summer monsoon,the second largest in winter,and the minimum occurred in autumn.
The significant climate characteristic in the South China Sea (SCS) during winter monsoon is that northeast monsoon is the prevailing wind and cold surges frequently occur.The features of sea-air heat flux and budget during the winter monsoon,especially during the cold surges,were studied,based on the data collected from the sea-air flux experiment in Yongxing Island,SCS,from October 2008 to April 2009.The results showed that:the sensible heat (SH) flux slightly increased during the prophase of winter monsoon with the increase of temperature difference between air and sea s compared to that during summer (southwest) monsoon.The average latent heat (LH) flux during winter monsoon was almost equal to that during the summer (southwest) monsoon.The total solar radiation decreased significantly,and the long wave radiation of the atmosphere also decreased,as a result,the net heat budget of the sea became negative value,which caused the sea surface temperature (SST) dropping after autumn.The SH fluxes during the cold surges were higher than the average flux during the winter monsoon,and before January,most of the LH fluxes during the cold surge were also higher than the average flux of winter monsoon.Due to the increase of SH flux and the decrease of solar radiation,the net heat budgets of the sea,during the cold surges before January,generally turned into high negative value,which caused the sea losing more heat than during winter monsoon,and even more than the average heat loss of the typhoons in 2008.At the end of winter monsoon,while the total solar radiation increased,the net heat budget of the sea turned to positive,so the SST increased gradually.Among all seasons,the SH flux in winter monsoon was the largest,the second largest in autumn,and the minimum in spring.The LH flux was the largest during summer monsoon,the second largest in winter,and the minimum occurred in autumn.
2012, 34(3): 41-54.
Abstract:
The Huangmaohai Estuary is located in the southwest of the Zhujiang(Pearl 1) River Delta (ZRD). Tidal propagation in the estuary endures complex variations from the offshore into the inland. Understanding its transformation processes and the underlying mechanisms is of great importance in both theoretical and practical perspectives. The Environmental Fluid Dynamics Code(EFDC) model was utilized and well calibrated by various sources of observation data. After then, the variations of tidal amplitudes and the phase differences between water level and current along its propagation were studied. The impacts of an upstream lock—Heshan Lock and the interaction between the estuary and the ZRD river-network were investigated. The model results clearly indicate that topography, bottom friction and the combination of incident and reflected waves all play important roles in the tidal propagation processes. The existence of Heshan Lock can impose an impact extending up to 100 km. The interaction between the estuary and the ZRD river-network results in a reduction of tidal amplitudes in the estuary. Comparisons among the Modaomen Estuary and the Lingding Bay-Humen-Guangzhou Estuary and the Huangmaohai Estuary demonstrate their unique characteristic.
The Huangmaohai Estuary is located in the southwest of the Zhujiang(Pearl 1) River Delta (ZRD). Tidal propagation in the estuary endures complex variations from the offshore into the inland. Understanding its transformation processes and the underlying mechanisms is of great importance in both theoretical and practical perspectives. The Environmental Fluid Dynamics Code(EFDC) model was utilized and well calibrated by various sources of observation data. After then, the variations of tidal amplitudes and the phase differences between water level and current along its propagation were studied. The impacts of an upstream lock—Heshan Lock and the interaction between the estuary and the ZRD river-network were investigated. The model results clearly indicate that topography, bottom friction and the combination of incident and reflected waves all play important roles in the tidal propagation processes. The existence of Heshan Lock can impose an impact extending up to 100 km. The interaction between the estuary and the ZRD river-network results in a reduction of tidal amplitudes in the estuary. Comparisons among the Modaomen Estuary and the Lingding Bay-Humen-Guangzhou Estuary and the Huangmaohai Estuary demonstrate their unique characteristic.
2012, 34(3): 55-60.
Abstract:
Based on the collected and coincident data between Jason-1 altimeter and buoy observations,a two-parameter wind speed model with altimeter-derived backscatter and significant wave height (SWH,Hsw) is developed.Besides,a feasibility study of using automatic gain control (AGC) to replace σ0 is explored.The experiment results show that the inversion accuracy of σ0-Hsw model is 0.3 m/s.The inversion accuracy of AGC-SWH model is lower(1.3 m/s).By Using cross calibration,the accuracy improves 0.9 m/s.It is a significant reference for "HY-2" that AGC-SWH inverses wind speed by cross calibration.
Based on the collected and coincident data between Jason-1 altimeter and buoy observations,a two-parameter wind speed model with altimeter-derived backscatter and significant wave height (SWH,Hsw) is developed.Besides,a feasibility study of using automatic gain control (AGC) to replace σ0 is explored.The experiment results show that the inversion accuracy of σ0-Hsw model is 0.3 m/s.The inversion accuracy of AGC-SWH model is lower(1.3 m/s).By Using cross calibration,the accuracy improves 0.9 m/s.It is a significant reference for "HY-2" that AGC-SWH inverses wind speed by cross calibration.
2012, 34(3): 61-71.
Abstract:
Although marine Hf isotope have been reported since the 1980s,they are not paid much attention to as a new proxy in tracing continental weathering and oceanic circulation until recently with the developments of analytical technology.The modern distribution of global seawater Hf isotopes and their Cenozoic evolution are reviewed.The most important phenomenon is that the seawater Nd-Hf isotopic compositions display a well-defined correlation,which clearly offsets from the terrestrial array.Based on these observations,the controversial issues on the sources of marine Hf isotopes are discussed,including the contributions of marine hydrothermal systems,continental incongruent weathering,dissolution of shelf and oceanic island sediments,and effect of different resident times between Hf and Nd.Clarifying the geochemical behavior of marine Hf is crucially important for better understanding the marine Hf cycling and paleoceanic evolution.
Although marine Hf isotope have been reported since the 1980s,they are not paid much attention to as a new proxy in tracing continental weathering and oceanic circulation until recently with the developments of analytical technology.The modern distribution of global seawater Hf isotopes and their Cenozoic evolution are reviewed.The most important phenomenon is that the seawater Nd-Hf isotopic compositions display a well-defined correlation,which clearly offsets from the terrestrial array.Based on these observations,the controversial issues on the sources of marine Hf isotopes are discussed,including the contributions of marine hydrothermal systems,continental incongruent weathering,dissolution of shelf and oceanic island sediments,and effect of different resident times between Hf and Nd.Clarifying the geochemical behavior of marine Hf is crucially important for better understanding the marine Hf cycling and paleoceanic evolution.
2012, 34(3): 72-79.
Abstract:
A distillation method for determining 15N abundance of nitrate in seawater was set up in this study.The method mainly involved the conversion of nitrate to ammonia using Devarda's alloy and the trapping of the ammonia with diluted HCl.After drying,nitrogen isotopic composition of the ammonium salts was measured by an isotopic ratio mass spectrometer.In this study,the amount of Devarda's alloy for nitrate reduction and the conditions for ammonium salts drying were assessed.A total of 3.0 g of Devarda's alloy was needed to completely reduce nitrate to ammonia in 2 dm3 seawater,and the drying of ammonium salts at 60 ℃ was appropriate for sample preparation for isotopic measurements.The overall nitrogen blank of our method was (0.90±0.19)μmol,and lower than those reported previously.The δ15N value of nitrogen blank was( -14.7±4.1)×10-3.Nitrogen isotopic composition determined by this method was well consistent with that measured by the ammonia diffusion method,demonstrating the reliability of this method.The ammonia distillation method was applicable for measurement of nitrogen isotopes in seawater with the nitrate concentration of 2~50 μmol/dm3.The precision for nitrogen isotope determination was within ±0.3×10-3.
A distillation method for determining 15N abundance of nitrate in seawater was set up in this study.The method mainly involved the conversion of nitrate to ammonia using Devarda's alloy and the trapping of the ammonia with diluted HCl.After drying,nitrogen isotopic composition of the ammonium salts was measured by an isotopic ratio mass spectrometer.In this study,the amount of Devarda's alloy for nitrate reduction and the conditions for ammonium salts drying were assessed.A total of 3.0 g of Devarda's alloy was needed to completely reduce nitrate to ammonia in 2 dm3 seawater,and the drying of ammonium salts at 60 ℃ was appropriate for sample preparation for isotopic measurements.The overall nitrogen blank of our method was (0.90±0.19)μmol,and lower than those reported previously.The δ15N value of nitrogen blank was( -14.7±4.1)×10-3.Nitrogen isotopic composition determined by this method was well consistent with that measured by the ammonia diffusion method,demonstrating the reliability of this method.The ammonia distillation method was applicable for measurement of nitrogen isotopes in seawater with the nitrate concentration of 2~50 μmol/dm3.The precision for nitrogen isotope determination was within ±0.3×10-3.
2012, 34(3): 80-86.
Abstract:
The sound speed ratio R1 of sediment to seawater and the sound speed ratio R2 of compressional wave to shear wave are added up to the vertical gradient of sound speed geoacoustic model (GM) so as to achieve a more comprehensive and instructional GM in practice.Considering stress-strain relations of two-phase medium of sediment under the effect of heat and gravity,TFCMCM and DFCMCM models are established on the basis of Men-Chen model by introducing a freedom factor and considering coupled-frame elastic modular (FCMCM).Both models are used to adjust the seafloor surface sediment sound speed characteristic into the in-situ state,calculate and interpret the GMs.According to analysis of the existence of high-speed and low-speed types in seafloor surface sediments and the two kinds of porosity-depth states of constant and descent beneath the seafloor sediment (PDC and PDD),four representative basic geoacoustic models of sediments in the South China Sea can be expressed as low-speed PDC,low-speed and porosity-PDD,high-speed PDC and high-speed PDD.With the usage of combination of the four basic models,the Lu Bo and Liang Yuanbo’s three sound-speed structures of the South China Sea can be rationally explained as an example of the actual sedimentary acoustic state.The understanding of basic geoacousic models will benefit the seafloor inspection and classification of sea bottom regions with acoustic methods in the South China Sea.
The sound speed ratio R1 of sediment to seawater and the sound speed ratio R2 of compressional wave to shear wave are added up to the vertical gradient of sound speed geoacoustic model (GM) so as to achieve a more comprehensive and instructional GM in practice.Considering stress-strain relations of two-phase medium of sediment under the effect of heat and gravity,TFCMCM and DFCMCM models are established on the basis of Men-Chen model by introducing a freedom factor and considering coupled-frame elastic modular (FCMCM).Both models are used to adjust the seafloor surface sediment sound speed characteristic into the in-situ state,calculate and interpret the GMs.According to analysis of the existence of high-speed and low-speed types in seafloor surface sediments and the two kinds of porosity-depth states of constant and descent beneath the seafloor sediment (PDC and PDD),four representative basic geoacoustic models of sediments in the South China Sea can be expressed as low-speed PDC,low-speed and porosity-PDD,high-speed PDC and high-speed PDD.With the usage of combination of the four basic models,the Lu Bo and Liang Yuanbo’s three sound-speed structures of the South China Sea can be rationally explained as an example of the actual sedimentary acoustic state.The understanding of basic geoacousic models will benefit the seafloor inspection and classification of sea bottom regions with acoustic methods in the South China Sea.
2012, 34(3): 87-91.
Abstract:
In order to improve seismic events’pickup precision, based on many of auto pickup methods, the author selects energy ratio and cross-correlation, and discusses their formula in detail. Testing with the actual data, author analyses their advantage and shortcoming each other, and take medium and average filtering to remove the spike and swell noise for the auto pickup result. To initialize the auto pickup value, the reference seed points are very important, and to pick these important reference seed points, user-computer interactive picking is necessary. In addition, the complex reflecting layers must be picked by the user-computer interactive picking. So user-computer interactive picking is also very important. In practice, auto pickup and user-computer interactive picking must be used simultaneously, and tested with actual data the pickup result is very good by using the above comprehensive methods.
In order to improve seismic events’pickup precision, based on many of auto pickup methods, the author selects energy ratio and cross-correlation, and discusses their formula in detail. Testing with the actual data, author analyses their advantage and shortcoming each other, and take medium and average filtering to remove the spike and swell noise for the auto pickup result. To initialize the auto pickup value, the reference seed points are very important, and to pick these important reference seed points, user-computer interactive picking is necessary. In addition, the complex reflecting layers must be picked by the user-computer interactive picking. So user-computer interactive picking is also very important. In practice, auto pickup and user-computer interactive picking must be used simultaneously, and tested with actual data the pickup result is very good by using the above comprehensive methods.
2012, 34(3): 92-98.
Abstract:
In order to probe seamount Co-rich crusts’ metal sources and their ore-forming environment, water column chemistry analyses were done at two sites (one site is just on the seamount slope and the another is relative far away the seamount) around a seamount in the central Pacific Ocean. The results reveal that the water chemical environments of the two sites are similar because of the similar distributions of dissolved oxygen concentration, pH and nutrients concentrations of these sites, two. but the metal element concentrations from the water column are obvious difference between the two sites, and the metal element concentrations at the site on the seamount slope are obvious higher than those of the site relative far away the seamount|the main metal is from the local seamount rocks, maybe related to the low temperature hydrothermal activity and the water-rock reaction. There are relative high metal concentrations in the bottom water near the seafloor at the two sites although there is the above-mentioned difference. This condition confirms the influence of the Antarctic Bottom Water(AABW) on this area, which is confirmed by the local distributions of the seawater potential temperatures, and shows that the AABW is a main factor to keep the relative strong oxidizing environment in the seawater on the seamount slope and has the ability of transporting partial ore-forming elements. The difference of the two sites maybe hints that there is a local metal source such as low temperature hydrothermal activity in this seamount area.
In order to probe seamount Co-rich crusts’ metal sources and their ore-forming environment, water column chemistry analyses were done at two sites (one site is just on the seamount slope and the another is relative far away the seamount) around a seamount in the central Pacific Ocean. The results reveal that the water chemical environments of the two sites are similar because of the similar distributions of dissolved oxygen concentration, pH and nutrients concentrations of these sites, two. but the metal element concentrations from the water column are obvious difference between the two sites, and the metal element concentrations at the site on the seamount slope are obvious higher than those of the site relative far away the seamount|the main metal is from the local seamount rocks, maybe related to the low temperature hydrothermal activity and the water-rock reaction. There are relative high metal concentrations in the bottom water near the seafloor at the two sites although there is the above-mentioned difference. This condition confirms the influence of the Antarctic Bottom Water(AABW) on this area, which is confirmed by the local distributions of the seawater potential temperatures, and shows that the AABW is a main factor to keep the relative strong oxidizing environment in the seawater on the seamount slope and has the ability of transporting partial ore-forming elements. The difference of the two sites maybe hints that there is a local metal source such as low temperature hydrothermal activity in this seamount area.
2012, 34(3): 99-105.
Abstract:
Palynological analyses combined with AMS14C dating were carried out in a gravity core BH-264 retrieved from a mud depositional system in the Huanghe River underwater delta (the Bohai Sea) to investigate the paleoclimate changes during the Holocene. In the early Holocene (9.5—7.6 ka BP) the pollen and spore assemblages indicate a warm and humid climate. During this stage, the Bohai seashore area is mainly composed of marshes as the vegetations mainly consisted of Cyperaceae and Typhaceae, and the surrounding mountainous, hilly and flat areas were mainly covered by Pinus and Deciduous quercus accompanied with Betula,Ulmaceae and Moraceae. In the mid-Holocene (7.6—5.8 ka BP), due to the increase of temperature and sea-level, Pinus dominated in the pollen and spore assemblages. However the content of pollen genus such as herb, which is not favourable totransportation for long distances, decreases to the lowest level in the Holocene in this warm stage. The East Asian summer monsoon (EASM) has decreased since 5.8 ka BP and as a result the rainfall in the surrounding area of Bohai Sea reduces and an arid environment dominates. Such xeric genus as Chenopodiaceae,Dendranthema,Artemisia are dominant in the seashore environment. Moreover, the formation of the Huanghe (Yellow River) Delta shortened the distance between the pollen supplying area and the investigation area, which resulted in higher efficiency for the transportation of pollen and spore to the sediment core BH-264.
Palynological analyses combined with AMS14C dating were carried out in a gravity core BH-264 retrieved from a mud depositional system in the Huanghe River underwater delta (the Bohai Sea) to investigate the paleoclimate changes during the Holocene. In the early Holocene (9.5—7.6 ka BP) the pollen and spore assemblages indicate a warm and humid climate. During this stage, the Bohai seashore area is mainly composed of marshes as the vegetations mainly consisted of Cyperaceae and Typhaceae, and the surrounding mountainous, hilly and flat areas were mainly covered by Pinus and Deciduous quercus accompanied with Betula,Ulmaceae and Moraceae. In the mid-Holocene (7.6—5.8 ka BP), due to the increase of temperature and sea-level, Pinus dominated in the pollen and spore assemblages. However the content of pollen genus such as herb, which is not favourable totransportation for long distances, decreases to the lowest level in the Holocene in this warm stage. The East Asian summer monsoon (EASM) has decreased since 5.8 ka BP and as a result the rainfall in the surrounding area of Bohai Sea reduces and an arid environment dominates. Such xeric genus as Chenopodiaceae,Dendranthema,Artemisia are dominant in the seashore environment. Moreover, the formation of the Huanghe (Yellow River) Delta shortened the distance between the pollen supplying area and the investigation area, which resulted in higher efficiency for the transportation of pollen and spore to the sediment core BH-264.
2012, 34(3): 106-113.
Abstract:
Diatom analyses were conducted on 13 surface sediment samples from the Bering Sea. A total of 56 species and varieties belonging to 30 genera were identified, among which 17 ones were documented from the Bering Sea for the first time, including three fossil taxa such as Kisseieviella carina. The dominant species were Neodenticula seminae, Fragilariopsis cylindrus and Fragilariopsis oceanica, with N. seminae dominated the vicinity of continental slope and the other two species dominated the northern continental shelf respectively. According to the results of cluster analysis, three diatom assemblages could be distinguished from the Bering Sea, which represented a sea-ice diatom assemblage, a pelagic planktonic diatom assemblage under strong influence of the Alaskan Stream and a transitional diatom assemblage.Fossula arctica is one of the 17 new records of diatom species from the Bering Sea with a distributional trend similar to that of F. cylindrus and F. oceanica, which amounts to 11.7%~17.1% on the northern continental shelf and sharply decreases on the adjacent parts of northern continental slope, so it is presumed to be another effective indicator of sea-ice variation other than F. cylindrus and F. oceanica, which can hopefully play an important role in study of late Quaternary sea-ice history in the Bering Sea.
Diatom analyses were conducted on 13 surface sediment samples from the Bering Sea. A total of 56 species and varieties belonging to 30 genera were identified, among which 17 ones were documented from the Bering Sea for the first time, including three fossil taxa such as Kisseieviella carina. The dominant species were Neodenticula seminae, Fragilariopsis cylindrus and Fragilariopsis oceanica, with N. seminae dominated the vicinity of continental slope and the other two species dominated the northern continental shelf respectively. According to the results of cluster analysis, three diatom assemblages could be distinguished from the Bering Sea, which represented a sea-ice diatom assemblage, a pelagic planktonic diatom assemblage under strong influence of the Alaskan Stream and a transitional diatom assemblage.Fossula arctica is one of the 17 new records of diatom species from the Bering Sea with a distributional trend similar to that of F. cylindrus and F. oceanica, which amounts to 11.7%~17.1% on the northern continental shelf and sharply decreases on the adjacent parts of northern continental slope, so it is presumed to be another effective indicator of sea-ice variation other than F. cylindrus and F. oceanica, which can hopefully play an important role in study of late Quaternary sea-ice history in the Bering Sea.
2012, 34(3): 114-119.
Abstract:
deep-water gravity-flow depositions are generally inferred that the sediments deposited by gravity flows outsidea continental shelf, the genesis, process and facies of such deposits show significant differences from traction current sediments such as fluvial, deltaic and shallow marine deposits.Currently, adeep-water exploration of large scale has been launched in the northern South China Sea.How to correctly understand the deep-water gravity-flow deposition shows its significance.However,the petroleum exploration lacks the practical experience in the deep-water gravity-flow deposition exploration in our country, and the understandings regarding to the deep-water gravity-flow deposition are different.For example, deepwater gravity-flow deposition have to be deposited at certain water depth; identification of deep-water deposits must request deep-water environment marking; the strata sedimentary bedding structures caused by deep-water sedimentary process must have gravity flow pattern and so on.According to the drilling data and the study of sedimentary systems of the northern South China Sea, the features of the deep-water gravity-flow deposition win be described as event-trigger mechanism, transportation along the slope, deposition in low places, and limited distribution.The coarse continental clastic matter deposits outside the continental shelf break show the genesis of gravity flow sediments and sandstone reservoir developed easily in low stand system tract of gravity flow.the key of the deep-water exploration is the reservoir identification, which characterized by continental slope deep-water deposits.
deep-water gravity-flow depositions are generally inferred that the sediments deposited by gravity flows outsidea continental shelf, the genesis, process and facies of such deposits show significant differences from traction current sediments such as fluvial, deltaic and shallow marine deposits.Currently, adeep-water exploration of large scale has been launched in the northern South China Sea.How to correctly understand the deep-water gravity-flow deposition shows its significance.However,the petroleum exploration lacks the practical experience in the deep-water gravity-flow deposition exploration in our country, and the understandings regarding to the deep-water gravity-flow deposition are different.For example, deepwater gravity-flow deposition have to be deposited at certain water depth; identification of deep-water deposits must request deep-water environment marking; the strata sedimentary bedding structures caused by deep-water sedimentary process must have gravity flow pattern and so on.According to the drilling data and the study of sedimentary systems of the northern South China Sea, the features of the deep-water gravity-flow deposition win be described as event-trigger mechanism, transportation along the slope, deposition in low places, and limited distribution.The coarse continental clastic matter deposits outside the continental shelf break show the genesis of gravity flow sediments and sandstone reservoir developed easily in low stand system tract of gravity flow.the key of the deep-water exploration is the reservoir identification, which characterized by continental slope deep-water deposits.
2012, 34(3): 120-126.
Abstract:
For study of sedimentary section records of organic matter in Sanggou Bay, the content of TOC and TN of the sediment from two stations was determined. Combined with sedimentary chronosequence, the TOC and TN of aquatic source before the Industrial Revolution,during the Industrial Revolution and after large-scale farming in Sanggou Bay was estimated. Meanwhile, an assessment of the quality of organic matter in the cultivated area of Sanggou Bay was generated. The main results are as follows: before the Industrial Revolution, TOC was steady relatively, but TN decreased slowly with increasing depth; during the Industrial Revolution, fluctuation of TOC and TN were both great; after the large-scale farming, TOC decreased gradually and stabilized, and TN increased significantly with the expansion of farming, moreover, TOC and TN in surface sediments in scallop farming area were lower than that in the kelp farming area. The change tendency of the source of organic matter was mix source-terrigenous source-mix source.In addition, the percentage of TOC and TN of aquatic source increased due to the action of large-scale farming, and there was a cumulative pollution of nitrogen in the kelp ocean-based cultivation area.
For study of sedimentary section records of organic matter in Sanggou Bay, the content of TOC and TN of the sediment from two stations was determined. Combined with sedimentary chronosequence, the TOC and TN of aquatic source before the Industrial Revolution,during the Industrial Revolution and after large-scale farming in Sanggou Bay was estimated. Meanwhile, an assessment of the quality of organic matter in the cultivated area of Sanggou Bay was generated. The main results are as follows: before the Industrial Revolution, TOC was steady relatively, but TN decreased slowly with increasing depth; during the Industrial Revolution, fluctuation of TOC and TN were both great; after the large-scale farming, TOC decreased gradually and stabilized, and TN increased significantly with the expansion of farming, moreover, TOC and TN in surface sediments in scallop farming area were lower than that in the kelp farming area. The change tendency of the source of organic matter was mix source-terrigenous source-mix source.In addition, the percentage of TOC and TN of aquatic source increased due to the action of large-scale farming, and there was a cumulative pollution of nitrogen in the kelp ocean-based cultivation area.
2012, 34(3): 127-133.
Abstract:
The muscle and oocyte ultrastructure of Calanus sinicus and Acartia spinicauda which exposed to CO2-driven acidified seawater in laboratory-controlled were observed under the transmission electron microscopy.The results showed that the orderly of myoneme of these two copepods were decreased with the concentration of CO2 increased.The higher cCO2 (0.20%,0.50% and 1.00%) had oxidative damage on the copepods.The electron-dense of oocytes of copepods were decreased with the increased cCO2. The spherical granule were concentrated or collapsed.The elevated cCO2 could induce the apoptosis and impact the quality of eggs of copepods.
The muscle and oocyte ultrastructure of Calanus sinicus and Acartia spinicauda which exposed to CO2-driven acidified seawater in laboratory-controlled were observed under the transmission electron microscopy.The results showed that the orderly of myoneme of these two copepods were decreased with the concentration of CO2 increased.The higher cCO2 (0.20%,0.50% and 1.00%) had oxidative damage on the copepods.The electron-dense of oocytes of copepods were decreased with the increased cCO2. The spherical granule were concentrated or collapsed.The elevated cCO2 could induce the apoptosis and impact the quality of eggs of copepods.
2012, 34(3): 134-145.
Abstract:
The macrobenthos samples collected from Changjiang Estuary, China in 2009 and 2010 were identified to clarify the current state, and the historical data obtained from essentially the same sampling area were analyzed to get the long-term trends and their response to environmental changes over the past 30 years. The average total species number exhibited an obvious fluctuation over this 30 year period, which includes three periods, e.g., period one-before 1990s, the total species number maintained relatively high value; period two-from 1990s to 2005, the total species number decreased markedly; and period three-after 2005, the total species number increased rapidly. The average biomass and the abundance also had similar trends over the last 30 years. The trends of species composition of macrobenthos community was that some long-lived, larger sized, stress intolerant resident species had been replaced by some opportunistic, short-lived, small sized taxa, especially some opportunistic polychaeta species, which indicated the macrobenthos community of the study area was unhealthy and unstable. The results of MDS ordination also approximately coincide with the above results. The integrated impacts both from climate changes and from anthropogenic disturbances, such as aquaculture, coastal land reclamation and sewage discharge were the triggers for these long-term changes.
The macrobenthos samples collected from Changjiang Estuary, China in 2009 and 2010 were identified to clarify the current state, and the historical data obtained from essentially the same sampling area were analyzed to get the long-term trends and their response to environmental changes over the past 30 years. The average total species number exhibited an obvious fluctuation over this 30 year period, which includes three periods, e.g., period one-before 1990s, the total species number maintained relatively high value; period two-from 1990s to 2005, the total species number decreased markedly; and period three-after 2005, the total species number increased rapidly. The average biomass and the abundance also had similar trends over the last 30 years. The trends of species composition of macrobenthos community was that some long-lived, larger sized, stress intolerant resident species had been replaced by some opportunistic, short-lived, small sized taxa, especially some opportunistic polychaeta species, which indicated the macrobenthos community of the study area was unhealthy and unstable. The results of MDS ordination also approximately coincide with the above results. The integrated impacts both from climate changes and from anthropogenic disturbances, such as aquaculture, coastal land reclamation and sewage discharge were the triggers for these long-term changes.
2012, 34(3): 146-154.
Abstract:
The annual Diel Vertical Migration (DVM) patterns of Zooplankton in Jiaozhou Bay were studied in four seasons during 2006 and 2007. The station was situated at 36°5'54″N,120°15'20″E, and samples were collected diel-continuously during 24 h in one day. The results showed that zooplankton acted differently during four seasons. In spring, they swam downward at noon and midnight, i.e. they acted as double cycles of rising and sinking, while in summer, zooplankton showed with the spring oppasite. In autumn, the center of density had a broader range than any other season, zooplankton seemed to stay at the upper layer at daylight, and to sink at night. In winter, zooplankton showed weaker DVM behavior, and the law was with the spring opposite.We studied the DVM characteristics of dominant species in Jiaozhou Bay and classified them into different groups as well. It was found that the ways and the time of the DVM for different species were different in the same season. As for the same species, they usually changed with seasons. As a result, for zooplankton, the DVM was always changing, it was determined not only by exogenous stressors but also by endogenous rhythms. And the key factors which contributed were not the same in four seasons. Sunlight was one of the key factors for all seasons. Besides, In winter, temperature, salinity and phytoplankton were also important. In total, zooplankton showed positive relationships with temperature and phytoplankton, and a negative relationship with salinity. Moreover,for specific species, the key factors which were responsible for the pattern of DVM were different.
The annual Diel Vertical Migration (DVM) patterns of Zooplankton in Jiaozhou Bay were studied in four seasons during 2006 and 2007. The station was situated at 36°5'54″N,120°15'20″E, and samples were collected diel-continuously during 24 h in one day. The results showed that zooplankton acted differently during four seasons. In spring, they swam downward at noon and midnight, i.e. they acted as double cycles of rising and sinking, while in summer, zooplankton showed with the spring oppasite. In autumn, the center of density had a broader range than any other season, zooplankton seemed to stay at the upper layer at daylight, and to sink at night. In winter, zooplankton showed weaker DVM behavior, and the law was with the spring opposite.We studied the DVM characteristics of dominant species in Jiaozhou Bay and classified them into different groups as well. It was found that the ways and the time of the DVM for different species were different in the same season. As for the same species, they usually changed with seasons. As a result, for zooplankton, the DVM was always changing, it was determined not only by exogenous stressors but also by endogenous rhythms. And the key factors which contributed were not the same in four seasons. Sunlight was one of the key factors for all seasons. Besides, In winter, temperature, salinity and phytoplankton were also important. In total, zooplankton showed positive relationships with temperature and phytoplankton, and a negative relationship with salinity. Moreover,for specific species, the key factors which were responsible for the pattern of DVM were different.
2012, 34(3): 155-162.
Abstract:
As the hub port of the international shipping center in Shanghai, more attention should be paid on marine fouling at Yangshan Port. In order to better understand the ecological characteristics of fouling organisms at Yangshan Port, this study explored the community structure and development trend using an annual panel test. The investigation spanned twelve months, from March 2009 to March 2010. Nineteen species of fouling organisms were identified, among which Ostrea cucullata,Balanus reliculatus,Membranipora grandicella,Sinoflustra amoyensis,Aspidelectra bihamata,Tubularia mesembryanthemum,Obelia geniculata and Sabellaria ishikawai were dominant species. Most species were cosmopolitan, some were euryoecous which usually present along the coast or near an estuary. Bioattachment occurred throughout the year except winter months, but the main period of settlement extended from June to October of 2009. The mean biomass of fouling organisms on the monthly, seasonal, and annual test panels were 9.20 g/m2, 127.20 g/m2 and 774.04 g/m2. By the analysis of community development and species succession, we found that fouling organisms at Yangshan Port have a unstable community structure and a varied species succession. This trend is closely related to the seasonal variation and increased salinity of Yangshan Port.
As the hub port of the international shipping center in Shanghai, more attention should be paid on marine fouling at Yangshan Port. In order to better understand the ecological characteristics of fouling organisms at Yangshan Port, this study explored the community structure and development trend using an annual panel test. The investigation spanned twelve months, from March 2009 to March 2010. Nineteen species of fouling organisms were identified, among which Ostrea cucullata,Balanus reliculatus,Membranipora grandicella,Sinoflustra amoyensis,Aspidelectra bihamata,Tubularia mesembryanthemum,Obelia geniculata and Sabellaria ishikawai were dominant species. Most species were cosmopolitan, some were euryoecous which usually present along the coast or near an estuary. Bioattachment occurred throughout the year except winter months, but the main period of settlement extended from June to October of 2009. The mean biomass of fouling organisms on the monthly, seasonal, and annual test panels were 9.20 g/m2, 127.20 g/m2 and 774.04 g/m2. By the analysis of community development and species succession, we found that fouling organisms at Yangshan Port have a unstable community structure and a varied species succession. This trend is closely related to the seasonal variation and increased salinity of Yangshan Port.
2012, 34(3): 163-172.
Abstract:
A marine oil-degrading bacterial consortium DC10 was prepared to an oil-degrading agent and further applied to the bioremediation of crude oil-contaminated Dalian beach. Field studies were carried out at the intertidal zone and supratidal zone respectively, and the effects of the oil-degrading agent were investigated by evaluating the decline of C17/hopane, C18/hopane, total petroleum alkanes and total petroleum aromatics.The oil-degrading consortium DC10 exhibited much higher degradation rates than the single degrader comprising consortium DC10 under laboratory conditions. Compared to the sterile control, the degradation rates of consortium DC10 increased by 60% in 7 days, and most alkanes and aromatics in oil were disappeared. The oil-degrading agent supplemented with essential nutrient salts was proved to be effective in the field study on the bioremediation of oil-contaminated Dalian beach. At the intertidal zone plot, the C17/hopane and C18/hopane degradation rates of bioremediation treatment increased by approximately 40% and 30% in 12 d, respectively, compared to the natural weathering. While the total alkanes and total aromatics degradation rates of bioremediation treatment increased by approximately 80% and 72% in 12 d. In the case of supratidal zone plot, the C17/hopane and C18/hopane degradation rates of bioremediation treatment was only slightly higher than natural weathering in 85 d. While the total alkanes and total aromatics degradation rates of bioremediation treatment increased by approximately 30% and 20% in 85 d, respectively.
A marine oil-degrading bacterial consortium DC10 was prepared to an oil-degrading agent and further applied to the bioremediation of crude oil-contaminated Dalian beach. Field studies were carried out at the intertidal zone and supratidal zone respectively, and the effects of the oil-degrading agent were investigated by evaluating the decline of C17/hopane, C18/hopane, total petroleum alkanes and total petroleum aromatics.The oil-degrading consortium DC10 exhibited much higher degradation rates than the single degrader comprising consortium DC10 under laboratory conditions. Compared to the sterile control, the degradation rates of consortium DC10 increased by 60% in 7 days, and most alkanes and aromatics in oil were disappeared. The oil-degrading agent supplemented with essential nutrient salts was proved to be effective in the field study on the bioremediation of oil-contaminated Dalian beach. At the intertidal zone plot, the C17/hopane and C18/hopane degradation rates of bioremediation treatment increased by approximately 40% and 30% in 12 d, respectively, compared to the natural weathering. While the total alkanes and total aromatics degradation rates of bioremediation treatment increased by approximately 80% and 72% in 12 d. In the case of supratidal zone plot, the C17/hopane and C18/hopane degradation rates of bioremediation treatment was only slightly higher than natural weathering in 85 d. While the total alkanes and total aromatics degradation rates of bioremediation treatment increased by approximately 30% and 20% in 85 d, respectively.
2012, 34(3): 173-178.
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2012, 34(3): 179-184.
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2012, 34(3): 185-189.
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2012, 34(3): 190-196.
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