2012 Vol. 34, No. 4
Display Method:
2012, 34(4): 1-11.
Abstract:
The primary way to retrieve dissolved organic carbon (DOC) from satellite is taking the absorption coefficient of dissolved organic matter (aCDOM) as a proxy based on its empirical relationship with DOC. Most researches on the remote sensing of DOC focused on the estuaries and river-dominated coastal oceans. In order to understand the mechanisms of DOC remote sensing, we collected the data from estuaries of global large rivers (16 in the top 25 global large rivers according to their discharge). It has been found that aCDOM behaves conservatively in most of the estuaries with salinity, while DOC usually shows a non-conservative behavior. Focusing on the analysis of the mechanisms and processes influencing the mixing behaviors of DOC and aCDOM, we discussed the progress of the remote sensing of DOC. Finally, we suggested that the factors influencing the DOC and aCDOM relationship should be considered and quantified based on the local biogeochemical characteristics.
The primary way to retrieve dissolved organic carbon (DOC) from satellite is taking the absorption coefficient of dissolved organic matter (aCDOM) as a proxy based on its empirical relationship with DOC. Most researches on the remote sensing of DOC focused on the estuaries and river-dominated coastal oceans. In order to understand the mechanisms of DOC remote sensing, we collected the data from estuaries of global large rivers (16 in the top 25 global large rivers according to their discharge). It has been found that aCDOM behaves conservatively in most of the estuaries with salinity, while DOC usually shows a non-conservative behavior. Focusing on the analysis of the mechanisms and processes influencing the mixing behaviors of DOC and aCDOM, we discussed the progress of the remote sensing of DOC. Finally, we suggested that the factors influencing the DOC and aCDOM relationship should be considered and quantified based on the local biogeochemical characteristics.
2012, 34(4): 12-20.
Abstract:
The massive nuclear leakage into ocean from Fukushima Nuclear Power Plant was observed on March 25th,2011. The transport of leaked radioactive pollutant from the Fukushima Nuclear Power Plant was simulated using a global version of Miami Isopycnic Coordinate Ocean Model (MICOM). The simulation was performed by assuming constant and continuous leakage for 20 days (scenario 1) and for one year (scenario 2) starting from March 25th,2011 and was integrated for 20 years. Taking into account of the annual and inter-annul variability of the ocean circulation,the model for each scenario was forced with four different time periods of NCEP/NCAR daily atmospheric forcing,namely,repeated 2010,1991-2011,1971-1991 and 1951-1971. There is no remarkable difference of transport pathways (both on surface and subsurface layers),transport timescales and vertical penetration for the nuclear waste among different ensemble members. An ensemble mean for each scenario was obtained in order to reduce the uncertainty in the simulations. The results of the ensembles indicate that the nuclear pollutant for both scenarios transports eastward to eastern Pacific and thereafter follows a southwest pathway towards the western Pacific. It takes about 10 to 15 years to reach the coast of East Asia. The transport pathway is governed by the ocean current system of the North Pacific Subtropical Gyre. The transport at the subsurface (100-400 m depth) is about 5 years faster than that at the surface when the nuclear signal reaches the coast of the East Asia. The time evolution of maximum tracer concentration shows that the surface and subsurface maximum concentrations of leaked nuclear pollutant at the end of the simulation are only 0.1% and 1% of the values at the first year. Most of nuclear pollutant stays in the North Pacific throughout the integration with almost 100% of the released nuclear pollutants remaining in the North Pacific for first 10 years and 86±1.5% at the end of the integration. The penetration depth of the nuclear pollutant is less than 1 000 m with relative high concentration between the surface and 600 m depth. The simulations also suggest that the ocean circulation and mixing instead of the source function dominate the variability of the maximum concentration. It should be emphasized that a realistic source function is required and atmospheric fallout and role of ocean ecology should also be taken into account,in order to get a more reliable assessment of possible impact of the radioactive leakage on the ocean environment.
The massive nuclear leakage into ocean from Fukushima Nuclear Power Plant was observed on March 25th,2011. The transport of leaked radioactive pollutant from the Fukushima Nuclear Power Plant was simulated using a global version of Miami Isopycnic Coordinate Ocean Model (MICOM). The simulation was performed by assuming constant and continuous leakage for 20 days (scenario 1) and for one year (scenario 2) starting from March 25th,2011 and was integrated for 20 years. Taking into account of the annual and inter-annul variability of the ocean circulation,the model for each scenario was forced with four different time periods of NCEP/NCAR daily atmospheric forcing,namely,repeated 2010,1991-2011,1971-1991 and 1951-1971. There is no remarkable difference of transport pathways (both on surface and subsurface layers),transport timescales and vertical penetration for the nuclear waste among different ensemble members. An ensemble mean for each scenario was obtained in order to reduce the uncertainty in the simulations. The results of the ensembles indicate that the nuclear pollutant for both scenarios transports eastward to eastern Pacific and thereafter follows a southwest pathway towards the western Pacific. It takes about 10 to 15 years to reach the coast of East Asia. The transport pathway is governed by the ocean current system of the North Pacific Subtropical Gyre. The transport at the subsurface (100-400 m depth) is about 5 years faster than that at the surface when the nuclear signal reaches the coast of the East Asia. The time evolution of maximum tracer concentration shows that the surface and subsurface maximum concentrations of leaked nuclear pollutant at the end of the simulation are only 0.1% and 1% of the values at the first year. Most of nuclear pollutant stays in the North Pacific throughout the integration with almost 100% of the released nuclear pollutants remaining in the North Pacific for first 10 years and 86±1.5% at the end of the integration. The penetration depth of the nuclear pollutant is less than 1 000 m with relative high concentration between the surface and 600 m depth. The simulations also suggest that the ocean circulation and mixing instead of the source function dominate the variability of the maximum concentration. It should be emphasized that a realistic source function is required and atmospheric fallout and role of ocean ecology should also be taken into account,in order to get a more reliable assessment of possible impact of the radioactive leakage on the ocean environment.
2012, 34(4): 21-26.
Abstract:
Based on the result of tidal current in the Xinhai area of Qiongzhou Strait, no matter f>0 or f<0, diurnal tidal spectrum peak is higher than the semidiurnal tidal spectrum peak. Among them, the cycles of semidiurnal tide are about 12.0 h and 12.4 h, and the cycles of diurnal tide are about 23.9 h and 25.8 h. In the component of diurnal and semidiurnal tide, the anti-clockwise component is the main component: clockwise diurnal spectrum is only 84% of anti-clockwise diurnal tidal energy spectrum; clockwise semidiurnal tidal energy spectrum is only 63% of anti-clockwise semidiurnal tidal energy spectrum. The main cycles of shallow-water tide are 8.3 h and 6.2 h, and others longer than one day, such as 4.2 d and 3 d, are also obvious, but they all don’t content significant test. The velocity of most residual currents ranges from 5 cm/s to 10 cm/s, some particulars are over 40 cm/s. Influenced by the anti-clockwise circulation movement, the main directions are in the range of NE,N and NW ,which make up more than 68% of the total observations. Wind also has significant effect: northeast wind will make direction of residual current to south, the north wind will make the direction of residual current to south.
Based on the result of tidal current in the Xinhai area of Qiongzhou Strait, no matter f>0 or f<0, diurnal tidal spectrum peak is higher than the semidiurnal tidal spectrum peak. Among them, the cycles of semidiurnal tide are about 12.0 h and 12.4 h, and the cycles of diurnal tide are about 23.9 h and 25.8 h. In the component of diurnal and semidiurnal tide, the anti-clockwise component is the main component: clockwise diurnal spectrum is only 84% of anti-clockwise diurnal tidal energy spectrum; clockwise semidiurnal tidal energy spectrum is only 63% of anti-clockwise semidiurnal tidal energy spectrum. The main cycles of shallow-water tide are 8.3 h and 6.2 h, and others longer than one day, such as 4.2 d and 3 d, are also obvious, but they all don’t content significant test. The velocity of most residual currents ranges from 5 cm/s to 10 cm/s, some particulars are over 40 cm/s. Influenced by the anti-clockwise circulation movement, the main directions are in the range of NE,N and NW ,which make up more than 68% of the total observations. Wind also has significant effect: northeast wind will make direction of residual current to south, the north wind will make the direction of residual current to south.
2012, 34(4): 27-34.
Abstract:
The study analyzes the interannual and decadal characteristics of South China Sea (SCS) surface latent heat flux according to the Objective Analysis of surface heat flux (OAflux), the SCS throughflow (that is indicated by the Luzon Strait transport, LST) inferred by the"Island Rule" theory and heat content in South China Sea. It reaches its peak in winter, and is the weakest in spring; In autumn and winter, latent heat flux is much larger in the North than that in the South, while it is larger in the South during summer. It shows that the SCS latent heat flux has been increasing since the beginning of 1980s. In the EOF analysis Mann-Kendall and trend methods of multi-time scales variation of the SCSlatent heat flux, the first three variances contribute: 53.01%(the major long-term trend), 17.4%(interdecadal change) and 6.71%(interannual change), respectively. It can be concluded that in the interannual scales, if LST gets weaker after flowing into the SCS, it will result in warmer sea surface temperature (SST) and smaller temperature difference between air and sea, which leads to a decrease in the latent heat flux, that is, a negative latent heat flux anomaly; On the contrary, if LST gets stronger, then the temperature difference between air and sea increases, causing a positive latetn heat flux anomaly.
The study analyzes the interannual and decadal characteristics of South China Sea (SCS) surface latent heat flux according to the Objective Analysis of surface heat flux (OAflux), the SCS throughflow (that is indicated by the Luzon Strait transport, LST) inferred by the"Island Rule" theory and heat content in South China Sea. It reaches its peak in winter, and is the weakest in spring; In autumn and winter, latent heat flux is much larger in the North than that in the South, while it is larger in the South during summer. It shows that the SCS latent heat flux has been increasing since the beginning of 1980s. In the EOF analysis Mann-Kendall and trend methods of multi-time scales variation of the SCSlatent heat flux, the first three variances contribute: 53.01%(the major long-term trend), 17.4%(interdecadal change) and 6.71%(interannual change), respectively. It can be concluded that in the interannual scales, if LST gets weaker after flowing into the SCS, it will result in warmer sea surface temperature (SST) and smaller temperature difference between air and sea, which leads to a decrease in the latent heat flux, that is, a negative latent heat flux anomaly; On the contrary, if LST gets stronger, then the temperature difference between air and sea increases, causing a positive latetn heat flux anomaly.
2012, 34(4): 35-40.
Abstract:
Based on the observed data in BaShan Lake, the evolution of observed temperature was simulated with MY2.5 parameterization scheme and κ-ε parameterization scheme under different surface boundary conditions. The simulated results were almost same with the two kinds of parameterization scheme under wind forcing surface boundary condition. When the wave breaking surface boundary condition developed by Mellor and Blumberg was considered, the simulated results with MY2.5 parameterization scheme were’t improved obviously but the results with κ-ε parameterization scheme were improved much which were similar with observed temperature profiles.
Based on the observed data in BaShan Lake, the evolution of observed temperature was simulated with MY2.5 parameterization scheme and κ-ε parameterization scheme under different surface boundary conditions. The simulated results were almost same with the two kinds of parameterization scheme under wind forcing surface boundary condition. When the wave breaking surface boundary condition developed by Mellor and Blumberg was considered, the simulated results with MY2.5 parameterization scheme were’t improved obviously but the results with κ-ε parameterization scheme were improved much which were similar with observed temperature profiles.
2012, 34(4): 41-52.
Abstract:
The Weather Research and Forecasting model (WRF) is employed to test the impacts of sea surface temperature (SST) on the track and intensity of Typhoon Jangmi, 2008 in the region of (15°-41°N, 105°-135°E). Firstly, two scenarios are conducted to test the sensitivities of radiation fluxes to SST. The model-computed radiation fluxes are compared with in-situ data and shows that WRF provides a reasonable prediction only for short-wave radiation fluxes but not for long-wave radiation fluxes in the first scenario. Hourly high resolution SST data from MASNUM wave-tide-circulation coupled system then used as bottom boundary of WRF for the second scenario. The scenario which use SST data from MASNUM system improved the short-wave and long-wave radiation and give a more accurate estimation. Two experiments are also conducted to simulate typhoon JANGMI during September 2008. The high resolution SST data from MASNUM system can improved the typhoon track forecast. The bias of center position of the typhoon reduces about 37% compared with the control experiment. The experiment by using SST from MASNUM model is more realistic than NCEP/NCARG SST from the control run.The results also can show that typhoon intensity has different sensitivity to sea surface temperature in different phase. The SST drop induced by typhoon decrease the heat fluxes transport from ocean to atmosphere and then weaken typhoon.
The Weather Research and Forecasting model (WRF) is employed to test the impacts of sea surface temperature (SST) on the track and intensity of Typhoon Jangmi, 2008 in the region of (15°-41°N, 105°-135°E). Firstly, two scenarios are conducted to test the sensitivities of radiation fluxes to SST. The model-computed radiation fluxes are compared with in-situ data and shows that WRF provides a reasonable prediction only for short-wave radiation fluxes but not for long-wave radiation fluxes in the first scenario. Hourly high resolution SST data from MASNUM wave-tide-circulation coupled system then used as bottom boundary of WRF for the second scenario. The scenario which use SST data from MASNUM system improved the short-wave and long-wave radiation and give a more accurate estimation. Two experiments are also conducted to simulate typhoon JANGMI during September 2008. The high resolution SST data from MASNUM system can improved the typhoon track forecast. The bias of center position of the typhoon reduces about 37% compared with the control experiment. The experiment by using SST from MASNUM model is more realistic than NCEP/NCARG SST from the control run.The results also can show that typhoon intensity has different sensitivity to sea surface temperature in different phase. The SST drop induced by typhoon decrease the heat fluxes transport from ocean to atmosphere and then weaken typhoon.
2012, 34(4): 53-60.
Abstract:
Atidal current is one of the main factors of underwater topography SAR imaging, and the underwater topography SAR imaging is related to the tidal current because of its periodic variability.The SAR images of the same topography acquiring at different time are different.Taking the Taiwan Shoal as study area, five scenes of ERS-2 SAR images are acquired at different time, and the in situ measured water depth is used in the correlation analysis of the tidal current and the underwater topography SAR imaging.These five SAR images are evaluated firstly by the traditional image evaluation method to avoid the influence of SAR imaging factors them selves on the underwater topography SAR imaging.Then the tidal current field of the SAR imaging is determined by the tide and tidal current numerical simulation, and the wind direction is obtained by the QuikSCAT.Based on the above work, the correlation between a SAR backscattering coefficient and the in situ measured water depth is analyzed, and the relation between the underwater topography SAR imaging and the tide time is concluded.The result shows that the underwater topography SAR imaging has closely relation to the tidal current filed, and the SAR image of the underwater topography is best when the direction of the tidal current is close to the grads direction of the water depth.The backscattering coefficients of two SAR images of the same topography acquired on the condition of two opposite tidal current directions is opposing, i.e., the bright-dark stripes are reverse.Furthermore, fair wind or head wind related to the tidal current direction have no influence on the underwater topography SAR imaging.
Atidal current is one of the main factors of underwater topography SAR imaging, and the underwater topography SAR imaging is related to the tidal current because of its periodic variability.The SAR images of the same topography acquiring at different time are different.Taking the Taiwan Shoal as study area, five scenes of ERS-2 SAR images are acquired at different time, and the in situ measured water depth is used in the correlation analysis of the tidal current and the underwater topography SAR imaging.These five SAR images are evaluated firstly by the traditional image evaluation method to avoid the influence of SAR imaging factors them selves on the underwater topography SAR imaging.Then the tidal current field of the SAR imaging is determined by the tide and tidal current numerical simulation, and the wind direction is obtained by the QuikSCAT.Based on the above work, the correlation between a SAR backscattering coefficient and the in situ measured water depth is analyzed, and the relation between the underwater topography SAR imaging and the tide time is concluded.The result shows that the underwater topography SAR imaging has closely relation to the tidal current filed, and the SAR image of the underwater topography is best when the direction of the tidal current is close to the grads direction of the water depth.The backscattering coefficients of two SAR images of the same topography acquired on the condition of two opposite tidal current directions is opposing, i.e., the bright-dark stripes are reverse.Furthermore, fair wind or head wind related to the tidal current direction have no influence on the underwater topography SAR imaging.
2012, 34(4): 61-66.
Abstract:
With reference to the Phase II methods for assessment of eutrophication status in estuarine and coastal waters used worldwide, and taking into consideration the ecological and environmental characteristics in coastal waters off China, a symptom-based method was established for assessment of eutrophication status in estuarine and coastal waters off China, with a framework of the Pressure-State-Response model. Application of the above method to the Changjiang Estuary indicated that the assessment result was the same as those of the main stream Phase II methods. Compared with the main stream Phase II methods, our method has advantages in easy availability of monitoring data, universality of application, and simplicity and ease of use.
With reference to the Phase II methods for assessment of eutrophication status in estuarine and coastal waters used worldwide, and taking into consideration the ecological and environmental characteristics in coastal waters off China, a symptom-based method was established for assessment of eutrophication status in estuarine and coastal waters off China, with a framework of the Pressure-State-Response model. Application of the above method to the Changjiang Estuary indicated that the assessment result was the same as those of the main stream Phase II methods. Compared with the main stream Phase II methods, our method has advantages in easy availability of monitoring data, universality of application, and simplicity and ease of use.
2012, 34(4): 67-76.
Abstract:
Kinetic experiments and the reactive continuum model were combined to characterize the reductive reactivity of iron(Ⅲ) oxides in surface and core sediments of the East China Sea.Three kinetic parameters,i.e.,theoretical amounts of total reactive iron(Ⅲ) oxides (m0),apparent rate constants (k'),and heterogeneity of reactivity (γ),were obtained by fitting kinetic data to the reactive continuum model.The results show that m0 values in the surface sediments are within a narrow range (26.14~60.51 μmol/g). Normalized initial rates (J/m0=k'),which characterize the kinetic behavior of highly reactive iron(Ⅲ) oxides,are also within a narrow range,with the highest initial rate being only 7.25 times the lowest.But heterogeneity of reductive reactivity of iron(Ⅲ) oxides in the surface sediments displays a wide range of variation.The kinetic rates after 90% dissolution of iron(Ⅲ) oxides are 2~4 orders of magnitude lower than the initial rates.The values of m0,k',and γ for core C0702 decrease generally with depth,and display good linear relationships between each other,which could be attributed to diagenetic cycling of iron in the sediments.However,no correlations among m0,k' and γ were observed in the surface sediments.In comparison with traditional chemical extraction methods,the reactive continuum model allows a more nuanced picture of the reactivity and kinetic manner of iron(Ⅲ) oxides in reductive dissolution.
Kinetic experiments and the reactive continuum model were combined to characterize the reductive reactivity of iron(Ⅲ) oxides in surface and core sediments of the East China Sea.Three kinetic parameters,i.e.,theoretical amounts of total reactive iron(Ⅲ) oxides (m0),apparent rate constants (k'),and heterogeneity of reactivity (γ),were obtained by fitting kinetic data to the reactive continuum model.The results show that m0 values in the surface sediments are within a narrow range (26.14~60.51 μmol/g). Normalized initial rates (J/m0=k'),which characterize the kinetic behavior of highly reactive iron(Ⅲ) oxides,are also within a narrow range,with the highest initial rate being only 7.25 times the lowest.But heterogeneity of reductive reactivity of iron(Ⅲ) oxides in the surface sediments displays a wide range of variation.The kinetic rates after 90% dissolution of iron(Ⅲ) oxides are 2~4 orders of magnitude lower than the initial rates.The values of m0,k',and γ for core C0702 decrease generally with depth,and display good linear relationships between each other,which could be attributed to diagenetic cycling of iron in the sediments.However,no correlations among m0,k' and γ were observed in the surface sediments.In comparison with traditional chemical extraction methods,the reactive continuum model allows a more nuanced picture of the reactivity and kinetic manner of iron(Ⅲ) oxides in reductive dissolution.
2012, 34(4): 77-83.
Abstract:
In the ocean,CO is mainly photoproduced by chromopheric dissolved organic matter (CDOM).It is of vital significance to study the effects of environmental factors,including radiation intensity,irradiation time,water temperature,pH,salinity and photobleaching time of CDOM,on CO photoproduction in seawater.The above mentioned variables on CO photoproduction were examined in surface seawater in the Jiaozhou Bay and its several river mouths in this paper.The results indicate that photoproduction rates of CO increase with radiation intensity,irradiation time,water temperature,pH and decrease with wavelength,salinity,respectively.Photoproduction rates of CO are different due to CDOM of various sources in the photochemical reactions.
In the ocean,CO is mainly photoproduced by chromopheric dissolved organic matter (CDOM).It is of vital significance to study the effects of environmental factors,including radiation intensity,irradiation time,water temperature,pH,salinity and photobleaching time of CDOM,on CO photoproduction in seawater.The above mentioned variables on CO photoproduction were examined in surface seawater in the Jiaozhou Bay and its several river mouths in this paper.The results indicate that photoproduction rates of CO increase with radiation intensity,irradiation time,water temperature,pH and decrease with wavelength,salinity,respectively.Photoproduction rates of CO are different due to CDOM of various sources in the photochemical reactions.
2012, 34(4): 84-90.
Abstract:
When predicting the sound velocity of sea-floor sediments, is not appropriate to sum up a uniform empirical equation from the sea-floor sediment data of different sea areas, where the sea-floor sediment’s physical properties are even completely different. Not only the data are discrete too, but the parameters in the equation are lack of exact physical meaning. Based on the idea of Wyllie’s time-average equation, a sea-floor sediment sound velocity forecasting model is established with the relationship of distance, time and velocity. In the model, the introduced parameter coupling coefficient stands for the impact of stacking and coupling mode of a solid-liquid two-phase system on a sound propagation.The measurement data of sea-floor sediment samples from offshore Luhuitou, the southern and northern South China sea are applied to verifying the model, and three different sound velocity forecasting equations are fitted out. The conclusion is the model can exactly reflect the relation between sound velocity and porosity, moreover, the parameters in the model have physical meaning.
When predicting the sound velocity of sea-floor sediments, is not appropriate to sum up a uniform empirical equation from the sea-floor sediment data of different sea areas, where the sea-floor sediment’s physical properties are even completely different. Not only the data are discrete too, but the parameters in the equation are lack of exact physical meaning. Based on the idea of Wyllie’s time-average equation, a sea-floor sediment sound velocity forecasting model is established with the relationship of distance, time and velocity. In the model, the introduced parameter coupling coefficient stands for the impact of stacking and coupling mode of a solid-liquid two-phase system on a sound propagation.The measurement data of sea-floor sediment samples from offshore Luhuitou, the southern and northern South China sea are applied to verifying the model, and three different sound velocity forecasting equations are fitted out. The conclusion is the model can exactly reflect the relation between sound velocity and porosity, moreover, the parameters in the model have physical meaning.
2012, 34(4): 91-98.
Abstract:
Owing to sea big wind wave and swell and so on, marine single channel seismic and subbottom profile data reflecting events often undulated, causing profile reflection horizons wrongs and confusions, and resolution and signal to noise ratio reduction. Therefore, according to the noise and the seabed reflection formation in the horizontal correlation with the change of frequency characteristics, as well as the comprehensive results of the previous studies, the land seismic data’s residual static correction processing in the statistical model trace’s cross-correlation method is used to reduce the influence of ocean wave on the reflecting events. in addition, in order to reduce of the effect of the high energy noise on correlation operation, uses the median filtering and smoothing filtering technology on the reflection events curve filtering are used to further reduce residual waves effects and related operational correction error. These methods will be integrated in the actual survey data processing of sea, large wind wave and swell under the influence of the wavy reflecting events become continuous and smooth, and under the sea clutter reflective layer it becomes clear and continuous, section signal-to-noise ratio and resolution are greatly improved.
Owing to sea big wind wave and swell and so on, marine single channel seismic and subbottom profile data reflecting events often undulated, causing profile reflection horizons wrongs and confusions, and resolution and signal to noise ratio reduction. Therefore, according to the noise and the seabed reflection formation in the horizontal correlation with the change of frequency characteristics, as well as the comprehensive results of the previous studies, the land seismic data’s residual static correction processing in the statistical model trace’s cross-correlation method is used to reduce the influence of ocean wave on the reflecting events. in addition, in order to reduce of the effect of the high energy noise on correlation operation, uses the median filtering and smoothing filtering technology on the reflection events curve filtering are used to further reduce residual waves effects and related operational correction error. These methods will be integrated in the actual survey data processing of sea, large wind wave and swell under the influence of the wavy reflecting events become continuous and smooth, and under the sea clutter reflective layer it becomes clear and continuous, section signal-to-noise ratio and resolution are greatly improved.
2012, 34(4): 99-108.
Abstract:
Mineralogical and geochemical studies have been carried out on an intact spire structure from Faulty Towers sulfide clusters. A sample displays four mineralogical zones from the exterior to the interior, i.e., a Fe-oxyhydroxide-barite-silica zone, a marcasite-pyrite-barite-silica zone, a marcasite-pyrite-sphalerite-wurzite zone, and a wurzite-chalcopyrite-marcasite zone, respectively. From the bottom to the top, there are three types of fluid conduits : irregular and discontinue multi-channels; oval-shape channel; and clogged channel. Mineralogy and mineral chemistry indicate low-teperature marcasite and wurtzite are the prominent mineral assemblage ,with minor chalcopyrite, only precipitated near the fluid conduits. Pb-210 data reflect that the walls formed in relatively short time (3 a), while the clogging of the fluid couduits goes through much longer time (17 a). Combined with microscopic study, the growth history of spire structure is recovered eventually.
Mineralogical and geochemical studies have been carried out on an intact spire structure from Faulty Towers sulfide clusters. A sample displays four mineralogical zones from the exterior to the interior, i.e., a Fe-oxyhydroxide-barite-silica zone, a marcasite-pyrite-barite-silica zone, a marcasite-pyrite-sphalerite-wurzite zone, and a wurzite-chalcopyrite-marcasite zone, respectively. From the bottom to the top, there are three types of fluid conduits : irregular and discontinue multi-channels; oval-shape channel; and clogged channel. Mineralogy and mineral chemistry indicate low-teperature marcasite and wurtzite are the prominent mineral assemblage ,with minor chalcopyrite, only precipitated near the fluid conduits. Pb-210 data reflect that the walls formed in relatively short time (3 a), while the clogging of the fluid couduits goes through much longer time (17 a). Combined with microscopic study, the growth history of spire structure is recovered eventually.
2012, 34(4): 109-120.
Abstract:
A platform with autonomous instruments was deployed over a period of 18 tide cycles in the south of Beibu Gulf to investigate sand transport and bedform dynamics, which collected continuous data of wave, current, SSC, and seabed changes. Analyses have been undertaken of SSC characteristics, suspended sediment flux, and the effect of current and wave on bedform dynamics and SSC variation. Results suggested that over the measurement period SSC variation was mainly affected by water-level fluctuation and current while wave was a less important factor. The exceedingly high SSC was probably caused by sediment sliding off the upstream sand wave. Suspended sediment flux changes comported with current velocity. There were presented remarkable variations of suspend sediment flux during flood-ebb and among tide cycles. A net transport for suspended sediment towards west and north were 15 158 kg·m-1 and 2 934 kg·m-1 respectively, the former of which was much larger than the latter under current. The limit of the EW-trending trough could lead to great difference between net transport flux in EW and in NS. The changes of seabed elevation varied among tide circles between 0.8 cm and 16.7 cm, which cm-scale bed level change in one tide cycle was probably generated by varying current velocity and asymmetric reversing current. These changes were most likely associated with migration of ripples. Sediment transporting downstream and modification of ripples’ profile gave reasonable interpretation of variation characteristics of seabed eletration.
A platform with autonomous instruments was deployed over a period of 18 tide cycles in the south of Beibu Gulf to investigate sand transport and bedform dynamics, which collected continuous data of wave, current, SSC, and seabed changes. Analyses have been undertaken of SSC characteristics, suspended sediment flux, and the effect of current and wave on bedform dynamics and SSC variation. Results suggested that over the measurement period SSC variation was mainly affected by water-level fluctuation and current while wave was a less important factor. The exceedingly high SSC was probably caused by sediment sliding off the upstream sand wave. Suspended sediment flux changes comported with current velocity. There were presented remarkable variations of suspend sediment flux during flood-ebb and among tide cycles. A net transport for suspended sediment towards west and north were 15 158 kg·m-1 and 2 934 kg·m-1 respectively, the former of which was much larger than the latter under current. The limit of the EW-trending trough could lead to great difference between net transport flux in EW and in NS. The changes of seabed elevation varied among tide circles between 0.8 cm and 16.7 cm, which cm-scale bed level change in one tide cycle was probably generated by varying current velocity and asymmetric reversing current. These changes were most likely associated with migration of ripples. Sediment transporting downstream and modification of ripples’ profile gave reasonable interpretation of variation characteristics of seabed eletration.
2012, 34(4): 121-134.
Abstract:
Subaqueous dunes are widely distributed in shallow marine environments. The morphological characteristics and the evolution of these bed forms have been a focus for many studies.The evolution of sand dunes associated with tidal flows is discussed using a one-dimensional modeling approach, in an attempt to identify the role played by the various factors and their interrelationships. The variables considered in this model include a water depth,a sediment grain size, and the thickness of sediment layer,and a typhoon. The simulation results show that the dune morphology and the evolution time are influenced by these factors. The spatial distribution of sand dunes is controlled by the flow field parameter; the dune height is influenced by the water depth,the sediment grain size and the thickness of sediment layer while the shape of sand dune depends on the thickness of sediment layer. The evolution time to reach equilibrium is controlled by all of the above factors. During a typhoon, the sediment is washed away from the ridge of dunes and then the heights decrease. Following the storm event, the sediment is transported back to the crest and the heights increase, however, several years are required to recover. The simulation results are consistent with the data of sand dunes from the Taiwan Bank in the Taiwan Strait and the southern North Sea in Europe.
Subaqueous dunes are widely distributed in shallow marine environments. The morphological characteristics and the evolution of these bed forms have been a focus for many studies.The evolution of sand dunes associated with tidal flows is discussed using a one-dimensional modeling approach, in an attempt to identify the role played by the various factors and their interrelationships. The variables considered in this model include a water depth,a sediment grain size, and the thickness of sediment layer,and a typhoon. The simulation results show that the dune morphology and the evolution time are influenced by these factors. The spatial distribution of sand dunes is controlled by the flow field parameter; the dune height is influenced by the water depth,the sediment grain size and the thickness of sediment layer while the shape of sand dune depends on the thickness of sediment layer. The evolution time to reach equilibrium is controlled by all of the above factors. During a typhoon, the sediment is washed away from the ridge of dunes and then the heights decrease. Following the storm event, the sediment is transported back to the crest and the heights increase, however, several years are required to recover. The simulation results are consistent with the data of sand dunes from the Taiwan Bank in the Taiwan Strait and the southern North Sea in Europe.
2012, 34(4): 135-146.
Abstract:
Modaomen estuary has been significantly changed by human activities and natural processes over the past decades. In order to study the evolution of the Modaomen Estuary during 1977-1988, a long-term (decadal-centennial scales) morphodynamic model which contains a rubble mound module and a waterway dredging mound module is developed to simulate the evolution of the Modaomen Estuary. The long-term simulation method and concept of model verification are discussed. Series of historical bathymetric charts are carefully analyzed to verify the model-simulated deposition and trends. The role of the human activities and natural process were separated based on the simulated result and situation analysis. The results of the numerical simulation and the morphodynamic analysis indicate that the sediment deposit of estuary on the west side is bigger than that on the east side, and affected by the riprap and reclamation project the main channel of Hengzhou is eroded by yearly, and the deep trough migrates seawards. However, the top of the Longshiku channel shows as severe deposition and channel continuously narrowing.
Modaomen estuary has been significantly changed by human activities and natural processes over the past decades. In order to study the evolution of the Modaomen Estuary during 1977-1988, a long-term (decadal-centennial scales) morphodynamic model which contains a rubble mound module and a waterway dredging mound module is developed to simulate the evolution of the Modaomen Estuary. The long-term simulation method and concept of model verification are discussed. Series of historical bathymetric charts are carefully analyzed to verify the model-simulated deposition and trends. The role of the human activities and natural process were separated based on the simulated result and situation analysis. The results of the numerical simulation and the morphodynamic analysis indicate that the sediment deposit of estuary on the west side is bigger than that on the east side, and affected by the riprap and reclamation project the main channel of Hengzhou is eroded by yearly, and the deep trough migrates seawards. However, the top of the Longshiku channel shows as severe deposition and channel continuously narrowing.
2012, 34(4): 147-154.
Abstract:
Based on the monthly surveys conducted in the Southern Huanghai Sea and Changjiang(Yangtze) River Estuary during March to May 2011,the temporal and spatial distribution features of green algae micro-propagules in water and sediment were studied.The results showed:the spatial distribution of micro-propagules in the waters increased gradually from inshore to offshore areas in the Southern Huanghai Sea.The high values were presented mainly in the adjacent Porphyra farming area,and no micro-propagules were detected to the east of 122°30' E. The average densities of micro-propagules in March,April and May were 144,164 and 140 inds/dm3 respectively,and the corresponding maximum densities were 278,426 and 537 inds/dm3 respectively.The content of micro-propagules in sediments ranged from 19 to 127 inds per layer,and this decreased with depth.Low density of micro-propagules (1-10 inds/dm3) were detected to the north of the Changjiang(Yangtze) River Estuary along the Jiangsu coast,while no micro-propagules were observed in the stations to the south of 31°N.Therefore,we could exclude the possibility that the green tide algae were carried into the sea by the Changjiang River or by the waters from south of the Changjiang(Yangtz) River Estuary.The research carried out, just before the breakout of green tide,was expected to predict the potential biomass of the green-tide Ulva species in seawater and provide technical support to green-tide control.
Based on the monthly surveys conducted in the Southern Huanghai Sea and Changjiang(Yangtze) River Estuary during March to May 2011,the temporal and spatial distribution features of green algae micro-propagules in water and sediment were studied.The results showed:the spatial distribution of micro-propagules in the waters increased gradually from inshore to offshore areas in the Southern Huanghai Sea.The high values were presented mainly in the adjacent Porphyra farming area,and no micro-propagules were detected to the east of 122°30' E. The average densities of micro-propagules in March,April and May were 144,164 and 140 inds/dm3 respectively,and the corresponding maximum densities were 278,426 and 537 inds/dm3 respectively.The content of micro-propagules in sediments ranged from 19 to 127 inds per layer,and this decreased with depth.Low density of micro-propagules (1-10 inds/dm3) were detected to the north of the Changjiang(Yangtze) River Estuary along the Jiangsu coast,while no micro-propagules were observed in the stations to the south of 31°N.Therefore,we could exclude the possibility that the green tide algae were carried into the sea by the Changjiang River or by the waters from south of the Changjiang(Yangtz) River Estuary.The research carried out, just before the breakout of green tide,was expected to predict the potential biomass of the green-tide Ulva species in seawater and provide technical support to green-tide control.
2012, 34(4): 155-162.
Abstract:
Prorocentrum triestinum Schiller (LAMB100721) is first time isolated in the East China Sea (ECS).Detailed morphological characteristic and molecular phylogenetics are described on the basis of observation under light microscopy, fluorescence microscopy, scanning electron microscopy and measurement of ITS sequences. The cells are lanceolate or heart-shaped.The anterior end is slightly excavated with an apical spine. The posterior end is pointed . The center of the cell is widest. Thecal surface is smooth, but contains tricocyst pores which are scattered apparently at the margin. The chloroplasts are irregular, distributed within the whole cell. The nucleus is rounded, located at the posterior part of the cell. The cell has a mean length of (22.6±0.9)μm (range 19-25 μm) and mean width of (13.2±1.1)μm (range 11-16 μm). The sequence length of the strain LAMB100721 is 569 bp. The GC content is 47.6%. Prorocentrum triestinum is a causative species of red tide. It has been co-occurred with Prorocentrum donghaiense in the ECS. Therefore, the precise identification and detection of the causative species were important for monitoring and early warning of harmful algal blooms.
Prorocentrum triestinum Schiller (LAMB100721) is first time isolated in the East China Sea (ECS).Detailed morphological characteristic and molecular phylogenetics are described on the basis of observation under light microscopy, fluorescence microscopy, scanning electron microscopy and measurement of ITS sequences. The cells are lanceolate or heart-shaped.The anterior end is slightly excavated with an apical spine. The posterior end is pointed . The center of the cell is widest. Thecal surface is smooth, but contains tricocyst pores which are scattered apparently at the margin. The chloroplasts are irregular, distributed within the whole cell. The nucleus is rounded, located at the posterior part of the cell. The cell has a mean length of (22.6±0.9)μm (range 19-25 μm) and mean width of (13.2±1.1)μm (range 11-16 μm). The sequence length of the strain LAMB100721 is 569 bp. The GC content is 47.6%. Prorocentrum triestinum is a causative species of red tide. It has been co-occurred with Prorocentrum donghaiense in the ECS. Therefore, the precise identification and detection of the causative species were important for monitoring and early warning of harmful algal blooms.
2012, 34(4): 163-171.
Abstract:
Effects of different seawater temperature(low temperature group 16℃, middle temperature 22℃ and high temperature 28℃) on sex differentiation and gonadal development in the amphioxus Branchiostoma belcheri without gonads and on the spawning and spermiation activity in mature amphioxus Branchiostoma belcheri at the breeding season were studied using the chronic experiment method.The immunological recognition of several reproduction-related hormones in the reproductive endocrine regulation organ(namely, Brain-hatschek’s pit-gonad) of amphioxus at different development stages was studied by immunohistochemistry and the testosterone and 17β-estradiol contents in gonads of amphioxus were detected by magnetic enzyme immunoassay to assay and investigate the endocrine mechanism of the effects of seawater temperature on reproductive activity of amphioxus. The results indicated that low sea water temperature promoted gonadal differentiation and development towards female in amphioxus, and the ratio of female to male was 4.2:1. There were no differences in sex ratio in the middle temperature group and in the high temperature group, but high seawater temperature could promote testis development and spermatogenic activity. The high temperature 28℃ was suitable for the reproductive activity of amphioxus. At the same time, the endocrine mechanism of the influence of temperature on the sex differentiation, gonadal development and reproductive activity in amphioxus was suggested by the results of immunohistochemistry and magnetic enzyme immunoassay as followed: Firstly, the seawater temperature may stimulate GnRH release from nervous system (brain vesicle) via skin receptor or chemical receptor of Hatschek’s pit. Then, GnRH may promote LH secretion from Hatschek’s pit. Finally, LH may stimulate the formation and secretion of sex steroid hormones in the ovary and testis, and thus initiate gonad development and maturation as well as reproductive activity.In addition,aromatase in the brain may be involved in the sex differentiation of amphioxus.
Effects of different seawater temperature(low temperature group 16℃, middle temperature 22℃ and high temperature 28℃) on sex differentiation and gonadal development in the amphioxus Branchiostoma belcheri without gonads and on the spawning and spermiation activity in mature amphioxus Branchiostoma belcheri at the breeding season were studied using the chronic experiment method.The immunological recognition of several reproduction-related hormones in the reproductive endocrine regulation organ(namely, Brain-hatschek’s pit-gonad) of amphioxus at different development stages was studied by immunohistochemistry and the testosterone and 17β-estradiol contents in gonads of amphioxus were detected by magnetic enzyme immunoassay to assay and investigate the endocrine mechanism of the effects of seawater temperature on reproductive activity of amphioxus. The results indicated that low sea water temperature promoted gonadal differentiation and development towards female in amphioxus, and the ratio of female to male was 4.2:1. There were no differences in sex ratio in the middle temperature group and in the high temperature group, but high seawater temperature could promote testis development and spermatogenic activity. The high temperature 28℃ was suitable for the reproductive activity of amphioxus. At the same time, the endocrine mechanism of the influence of temperature on the sex differentiation, gonadal development and reproductive activity in amphioxus was suggested by the results of immunohistochemistry and magnetic enzyme immunoassay as followed: Firstly, the seawater temperature may stimulate GnRH release from nervous system (brain vesicle) via skin receptor or chemical receptor of Hatschek’s pit. Then, GnRH may promote LH secretion from Hatschek’s pit. Finally, LH may stimulate the formation and secretion of sex steroid hormones in the ovary and testis, and thus initiate gonad development and maturation as well as reproductive activity.In addition,aromatase in the brain may be involved in the sex differentiation of amphioxus.
2012, 34(4): 172-180.
Abstract:
Physical model experiments are conducted to study the hydrodynamic characteristic of submarine piggyback pipeline under regular wave-current and irregular wave-current actions.Based on Morison equation, drag coefficient CD, inertia coefficient CM and lift coefficient CL(CL+,CL-) are obtained with the method of "equivalent diameter". In the experiments, effects of current ratio Uc/Uw, gap ratio between the large pipeline and the seabed e/D and spacing ratio between the large pipeline and the small pipeline G/D on the hydrodynamic coefficients of submarine piggyback pipeline are investigated. The results indicate that the hydrodynamic coefficients decrease with the increase of Uc/Uw.The effect of the seabed on the hydrodynamic forces on the piggyback pipeline is pronounced for e/D<0.5.CD,CM and CL+ decrease with the increase of e/D,and |CL-| increases with the increase of e/D. In addition, the interaction between the large pipeline and the small pipeline is not negligible.CD,CM and |CL-| decrease with the increase of G/D,and CL+ increases with the increase of G/D.
Physical model experiments are conducted to study the hydrodynamic characteristic of submarine piggyback pipeline under regular wave-current and irregular wave-current actions.Based on Morison equation, drag coefficient CD, inertia coefficient CM and lift coefficient CL(CL+,CL-) are obtained with the method of "equivalent diameter". In the experiments, effects of current ratio Uc/Uw, gap ratio between the large pipeline and the seabed e/D and spacing ratio between the large pipeline and the small pipeline G/D on the hydrodynamic coefficients of submarine piggyback pipeline are investigated. The results indicate that the hydrodynamic coefficients decrease with the increase of Uc/Uw.The effect of the seabed on the hydrodynamic forces on the piggyback pipeline is pronounced for e/D<0.5.CD,CM and CL+ decrease with the increase of e/D,and |CL-| increases with the increase of e/D. In addition, the interaction between the large pipeline and the small pipeline is not negligible.CD,CM and |CL-| decrease with the increase of G/D,and CL+ increases with the increase of G/D.
2012, 34(4): 181-187.
Abstract:
2012, 34(4): 188-194.
Abstract:
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