2001 Vol. 20, No. 4
Display Method:
2001, (4): 455-472.
Abstract:
The Casulli's difference scheme was introduced into the three-dimensional ocean model in the present paper, and the wind-driven current and thermohaline current were simulated. The results show that, southwesterly monsoon in summer induces a clockwise circulation in the Beibu Gulf, and the density gradient induces a counter-clockwise one; but the density current is more intense than the winddriven one in summer, especially in surface layer. In addition, the northeasterly monsoon in winter induces a counter-clockwise circulation. The simulated results don't support the traditional conclusion that there is a clockwise circulation in the Beibu Gulf in summer and a counter-clockwise one in winter, but support the statement that a counter-clockwise circulation exists in the Beibu Gulf all year round.
The Casulli's difference scheme was introduced into the three-dimensional ocean model in the present paper, and the wind-driven current and thermohaline current were simulated. The results show that, southwesterly monsoon in summer induces a clockwise circulation in the Beibu Gulf, and the density gradient induces a counter-clockwise one; but the density current is more intense than the winddriven one in summer, especially in surface layer. In addition, the northeasterly monsoon in winter induces a counter-clockwise circulation. The simulated results don't support the traditional conclusion that there is a clockwise circulation in the Beibu Gulf in summer and a counter-clockwise one in winter, but support the statement that a counter-clockwise circulation exists in the Beibu Gulf all year round.
2001, (4): 473-481.
Abstract:
A dynamic numerical prediction model of sea water temperature for limited sea area is used to predict the sea water temperature at the sea area near Fujian. Essential adjustments have been made in accordance with the characteristics of this region. Two tests have been made. One is in summer (3 d) and the other is in winter (10 d). In the summer test, a typhoon is just passing by and the calculated current field well responds to typhoon. In the winter test, variation tendency of the predicted sea water temperature field agrees with that of the observation basically, the absolute mean error in the whole sea area is 0.6℃. The variation of the sea water temperature is mostly affected by entrainment and pumping, which is related to the topography of the strait.
A dynamic numerical prediction model of sea water temperature for limited sea area is used to predict the sea water temperature at the sea area near Fujian. Essential adjustments have been made in accordance with the characteristics of this region. Two tests have been made. One is in summer (3 d) and the other is in winter (10 d). In the summer test, a typhoon is just passing by and the calculated current field well responds to typhoon. In the winter test, variation tendency of the predicted sea water temperature field agrees with that of the observation basically, the absolute mean error in the whole sea area is 0.6℃. The variation of the sea water temperature is mostly affected by entrainment and pumping, which is related to the topography of the strait.
2001, (4): 483-492.
Abstract:
Kalman filter data assimilation technique is incorporated into a standard two-dimensional linear storm surge model. Imperfect model equation and imperfect meteorological forcimg are accounted for by adding noise terms to the momentum equations. The deterministic model output is corrected by using the available tidal gauge station data. The stationary Kalman filter algorithm for the model domain is calculated by an iterative procedure using specified information on the inaccuracies in the momentum equations and specified error information for the observations. An application to a real storm surge that occurred in the summer of 1956 in the East China Sea is performed by means of this data assimilation technique. The result shows that Kalman filter is useful for storm surge forecast and hindcast.
Kalman filter data assimilation technique is incorporated into a standard two-dimensional linear storm surge model. Imperfect model equation and imperfect meteorological forcimg are accounted for by adding noise terms to the momentum equations. The deterministic model output is corrected by using the available tidal gauge station data. The stationary Kalman filter algorithm for the model domain is calculated by an iterative procedure using specified information on the inaccuracies in the momentum equations and specified error information for the observations. An application to a real storm surge that occurred in the summer of 1956 in the East China Sea is performed by means of this data assimilation technique. The result shows that Kalman filter is useful for storm surge forecast and hindcast.
2001, (4): 493-504.
Abstract:
An ecosystem-based water quality model was designed to estimate the biochemical reaction of nutrient and dissolved oxygen in conjunction with a three-dimensional hydrodynamic and sediment model. As both phosphorus and nitrogen successively limit phytoplankton growth in many estuaries, the model simulates both these nutrient cycles each using five variables, namely, dissolved inorganic nutrient, detritic organic matter, benthic matter, phytoplankton and zooplankton.
An ecosystem-based water quality model was designed to estimate the biochemical reaction of nutrient and dissolved oxygen in conjunction with a three-dimensional hydrodynamic and sediment model. As both phosphorus and nitrogen successively limit phytoplankton growth in many estuaries, the model simulates both these nutrient cycles each using five variables, namely, dissolved inorganic nutrient, detritic organic matter, benthic matter, phytoplankton and zooplankton.
2001, (4): 505-514.
Abstract:
In the present study, the ecosystem-based water quality model was applied to the Pearl River (Zhujiang) Estuary. The model results successfully represent the distribution trend of nutrients and dissolved oxygen both in the horizontal and vertical planes during the flood season, and it shows that the model has taken into consideration the key part of the dynamical, chemical and biological processes existing in the Zhujiang Estuary. The further studies illustrate that nitrogen is in plenty while phosphorus and light limit the phytoplankton biomass in the Zhujiang Estuary during the flood season.
In the present study, the ecosystem-based water quality model was applied to the Pearl River (Zhujiang) Estuary. The model results successfully represent the distribution trend of nutrients and dissolved oxygen both in the horizontal and vertical planes during the flood season, and it shows that the model has taken into consideration the key part of the dynamical, chemical and biological processes existing in the Zhujiang Estuary. The further studies illustrate that nitrogen is in plenty while phosphorus and light limit the phytoplankton biomass in the Zhujiang Estuary during the flood season.
2001, (4): 515-522.
Abstract:
A total of 106 surface water samples were collected in the South China Sea during two transects in June and December 1998. The samples were collected with strictly contamination free procedure and trace metals were measured by clean laboratory methods and GFAAS. The mean concentrations for the dissolved fractions are:Cu 0.100 μg/dm3, Pb 0.060 μg/dm3, Zn 0.086 μg/dm3, Cd 0.007 μg/dm3, which is close to the world open ocean's level. The spatial distribution of the trace heavy metals shows higher concentrations in offshore area and lower concentrations in the central in the South China Sea, and the concentrations decrease with the distance from the offshore, which suggests the existence of significant continental shelf input of the trace heavy metals. The correlationship among the elements is better in summer than that in winter. Cu is positively correlated with Cd in both seasons and it is also found for the first time that they are positively correlated with nutrients in the South China Sea surface waters which further indicate the biogeochemical cycle of these elements in the marine environment. The baseline value of Cu, Pb, Zn, Cd in the South China Sea surface waters is obtained through statistical analysis.
A total of 106 surface water samples were collected in the South China Sea during two transects in June and December 1998. The samples were collected with strictly contamination free procedure and trace metals were measured by clean laboratory methods and GFAAS. The mean concentrations for the dissolved fractions are:Cu 0.100 μg/dm3, Pb 0.060 μg/dm3, Zn 0.086 μg/dm3, Cd 0.007 μg/dm3, which is close to the world open ocean's level. The spatial distribution of the trace heavy metals shows higher concentrations in offshore area and lower concentrations in the central in the South China Sea, and the concentrations decrease with the distance from the offshore, which suggests the existence of significant continental shelf input of the trace heavy metals. The correlationship among the elements is better in summer than that in winter. Cu is positively correlated with Cd in both seasons and it is also found for the first time that they are positively correlated with nutrients in the South China Sea surface waters which further indicate the biogeochemical cycle of these elements in the marine environment. The baseline value of Cu, Pb, Zn, Cd in the South China Sea surface waters is obtained through statistical analysis.
2001, (4): 523-533.
Abstract:
The profiles of nutrient salts in the interstitial water of sediment were analyzed in the Zhujiang Estuary in the summer of 1999, and based on the profiles of content and characteristic of nutrients, the relationship between nutrients in the interstitial water and organic matter decomposition in sediment was discussed. The results showed that ammonium with high content was the main existence form of nutrients in the interstital water of sediment, and the organic matter decomposition was completed in anaerobic condition. The increase of ammonium content in the bottom water resulted from the decomposition of organic matter and release of metabolic production, and the ammonium bottom flux was an important resource for nutrients geochemistry in the Zhujiang Estuary.
The profiles of nutrient salts in the interstitial water of sediment were analyzed in the Zhujiang Estuary in the summer of 1999, and based on the profiles of content and characteristic of nutrients, the relationship between nutrients in the interstitial water and organic matter decomposition in sediment was discussed. The results showed that ammonium with high content was the main existence form of nutrients in the interstital water of sediment, and the organic matter decomposition was completed in anaerobic condition. The increase of ammonium content in the bottom water resulted from the decomposition of organic matter and release of metabolic production, and the ammonium bottom flux was an important resource for nutrients geochemistry in the Zhujiang Estuary.
2001, (4): 535-551.
Abstract:
This paper reports different concentration patterns of n-alkanes distribution in the sediments from the Chukchi Sea, the Bering Sea in the Arctic. Factor statistical analysis method is used for studying the source of n-alkanes and paleoenviroment. The result shows that n-alkanes is in the range of nC15~nC33 and n-alkane distribution patterns are characterized by two modes. The first mode belongs to the higher molecular with MH being nC25~nC27, CPI> 1 and with remarkable odd-even dominance.They are of terrigenous plant origin. The second one belongs to lower carbon range with MH being nC17~nC20, CPI> 1 and with indistinct odd-even dominance. Therefore they are contributed by marine biological inputs. The contribution of land origin is larger than that of marine source. Pr/Ph is lower than 1 in the investigated area, which indicates the depositional environment of reducing reaction with lower oxygen. The result of factor analysis has good agreement with composition characteristics of n-alkanes in the sediment.
This paper reports different concentration patterns of n-alkanes distribution in the sediments from the Chukchi Sea, the Bering Sea in the Arctic. Factor statistical analysis method is used for studying the source of n-alkanes and paleoenviroment. The result shows that n-alkanes is in the range of nC15~nC33 and n-alkane distribution patterns are characterized by two modes. The first mode belongs to the higher molecular with MH being nC25~nC27, CPI> 1 and with remarkable odd-even dominance.They are of terrigenous plant origin. The second one belongs to lower carbon range with MH being nC17~nC20, CPI> 1 and with indistinct odd-even dominance. Therefore they are contributed by marine biological inputs. The contribution of land origin is larger than that of marine source. Pr/Ph is lower than 1 in the investigated area, which indicates the depositional environment of reducing reaction with lower oxygen. The result of factor analysis has good agreement with composition characteristics of n-alkanes in the sediment.
2001, (4): 553-561.
Abstract:
COMRA (China Ocean Mineral Resources Association) registered pioneer area (CRPA) is located in the western part of the area between the Clarion and Clipperton Fraction Zones (CCFZs).Based on distinctive color and bio-disturbing properties, two layers are recognized in the sediment columns from the CRPA:a pale brown layer (Unit A) on the top and a dark brown layer (Unit B) in the lower part. Color division between them can be explained as a hiatus. As a result, the two units are different to each other in chemical composition and sediment properties. It is found that contents of P2O5, MnO2, CaO, Na2O in sediments of older Unit B are higher, but SiO2 content is slightly lower.Based on correlation analysis, Mn and Fe in the sediments have different origins. The former is mainly precipitated in authigenic process, whilst the latter is closely related to terrigenous detritus. Therefore,the differences in chemical composition of the sediments are caused by different sedimentation settings.
COMRA (China Ocean Mineral Resources Association) registered pioneer area (CRPA) is located in the western part of the area between the Clarion and Clipperton Fraction Zones (CCFZs).Based on distinctive color and bio-disturbing properties, two layers are recognized in the sediment columns from the CRPA:a pale brown layer (Unit A) on the top and a dark brown layer (Unit B) in the lower part. Color division between them can be explained as a hiatus. As a result, the two units are different to each other in chemical composition and sediment properties. It is found that contents of P2O5, MnO2, CaO, Na2O in sediments of older Unit B are higher, but SiO2 content is slightly lower.Based on correlation analysis, Mn and Fe in the sediments have different origins. The former is mainly precipitated in authigenic process, whilst the latter is closely related to terrigenous detritus. Therefore,the differences in chemical composition of the sediments are caused by different sedimentation settings.
2001, (4): 563-574.
Abstract:
The epidemiological investigations on the disease and death in mature eggs, embryonic developmental periods and larvae populations[including oocytes, fertilized ovum, early embryonic phase larvae (6 h), D-shaped phase larvae (24 h), early umbo phase larvae, umbo phase larvae, post umbo phase larvae and eyespot phase larvae] in the Luhuitou Pearl Oyster Mariculture Farm of Sanya City,Hainan Province in April 1995 showed that there were two peaks of mortality rates which occurred in early umbo phase or umbo phase and post umbo phase (Figs 3~5 and Table 1) respectively from preembryonic developmental periods to larvae phases. It indicated that the onset and death of Pinctada maxima larvae populations followed a pattern of outbreak. Between the prevalence, intensity of RLO infection and the mortality rates of larvae populations were of obvious positively correlations. Generally,every peak of RLO infection is always followed by a peak of mortality rate of larvae hosts, and the mortality rates of larvae hosts declined with the decreased RLO infection (see Figs 3~5). Under the transmission electron microscopy (TEM), no rickettsia-like organisms were discovered in oocytes, fertilized ovum and early embryonic phase larvae (6 h). The RLO inclusions occurred first in the D-shaped phase larvae (24 h) under histological examination. Absences of RLO in transmission electron examination of oocytes of RLO-infected adult females, fertilized ovum and early embryonic phase larvae (6h) indicated that RLO may not be transmitted transovarially. But RLO for host infection may be transmitted by contact transmission since RLO inclusions were first identified regularly in D-shaped phase larvae (24 h), while these D-shaped phase larvae were still unable to take food during hatching 24 hours. In addition, the result of epidemiological investigation showed that no observable death occurred in D-shaped larvae populations, but early obvious death occurred in larvae populations in the seventh day after fertilization, in a rate of about 21.8%. It indicated that there was a incubation period from RLO infection for host (D-shaped phase larvae) to host onset and death occurred clinically.
The epidemiological investigations on the disease and death in mature eggs, embryonic developmental periods and larvae populations[including oocytes, fertilized ovum, early embryonic phase larvae (6 h), D-shaped phase larvae (24 h), early umbo phase larvae, umbo phase larvae, post umbo phase larvae and eyespot phase larvae] in the Luhuitou Pearl Oyster Mariculture Farm of Sanya City,Hainan Province in April 1995 showed that there were two peaks of mortality rates which occurred in early umbo phase or umbo phase and post umbo phase (Figs 3~5 and Table 1) respectively from preembryonic developmental periods to larvae phases. It indicated that the onset and death of Pinctada maxima larvae populations followed a pattern of outbreak. Between the prevalence, intensity of RLO infection and the mortality rates of larvae populations were of obvious positively correlations. Generally,every peak of RLO infection is always followed by a peak of mortality rate of larvae hosts, and the mortality rates of larvae hosts declined with the decreased RLO infection (see Figs 3~5). Under the transmission electron microscopy (TEM), no rickettsia-like organisms were discovered in oocytes, fertilized ovum and early embryonic phase larvae (6 h). The RLO inclusions occurred first in the D-shaped phase larvae (24 h) under histological examination. Absences of RLO in transmission electron examination of oocytes of RLO-infected adult females, fertilized ovum and early embryonic phase larvae (6h) indicated that RLO may not be transmitted transovarially. But RLO for host infection may be transmitted by contact transmission since RLO inclusions were first identified regularly in D-shaped phase larvae (24 h), while these D-shaped phase larvae were still unable to take food during hatching 24 hours. In addition, the result of epidemiological investigation showed that no observable death occurred in D-shaped larvae populations, but early obvious death occurred in larvae populations in the seventh day after fertilization, in a rate of about 21.8%. It indicated that there was a incubation period from RLO infection for host (D-shaped phase larvae) to host onset and death occurred clinically.
2001, (4): 575-583.
Abstract:
A fuzzy mathematical method is used to discriminate the similarities of pelagic fishes landed in the 9180 hauls by 10 light-seine information yessels in the southern Fujian waters from 1989 to 1998. The results indicate that the dominant species of the communities had an obvious alternation and the fuzzy adjacency of annual species composition varied between 0.659 and 0.923 with an average value of 0.791. The fuzzy clustering analysis indicates that the annual fuzzy adjacency in general remains good although the species composition of the pelagic fishes has changed to a certain degree since 1992. This paper concludes that the community structure of pelagic fishes in the southern Taiwan Strait remains relatively stable and the state of fish stocks shows a good potentiality for a larger utilization.
A fuzzy mathematical method is used to discriminate the similarities of pelagic fishes landed in the 9180 hauls by 10 light-seine information yessels in the southern Fujian waters from 1989 to 1998. The results indicate that the dominant species of the communities had an obvious alternation and the fuzzy adjacency of annual species composition varied between 0.659 and 0.923 with an average value of 0.791. The fuzzy clustering analysis indicates that the annual fuzzy adjacency in general remains good although the species composition of the pelagic fishes has changed to a certain degree since 1992. This paper concludes that the community structure of pelagic fishes in the southern Taiwan Strait remains relatively stable and the state of fish stocks shows a good potentiality for a larger utilization.
2001, (4): 585-596.
Abstract:
The effect of estradiol-17β (E2)treatment on the pituitary-thyroidal axis has been investigated in female Japanese eels in seawater. The eels were injected with 1 mg/kg body weight (BW)weekly for two to eight weeks; another group was treated with 5 mg/kg BW weekly for eight weeks and sacrificed three days after the last injection. In the pituitary, using RT-PCR system, the thyroid stimulating hormone β subunit mRNA (TSHβ mRNA) level is slowly increased in the low-dose E2 treatment group. A significant increase in values occurred after eight weeks E2 injections. The histological structure of the thyroid follicles suggests a hypo-activity as shown by a reduced epithelial cell height in eels injected with E2 after six and eight times, and eventually reached a minimum level after eight weeks. Using radioimmunoassay of thyroxine (T4), triiodothyronine (T3) in the serum, a slowly decrease of both hormones is demonstrated. On the other hand, the TSHβ mRNA level is significantly increased from initial in the high-dose E2 treatment group. The histological structure of the thyroid follicles suggests a hypoactivity, and a sharp decrease of the both hormones is also indicated. These data suggest that the expression of TSHβ mRNA level is increased and thyroid hormone release is depressed by E2, the effects depend upon E2 injection period and dose. Furthermore, E2 could not directly influence the TSHβ mRNA expression and, TSH transcription might be controlled by a negative feedback of thyroid hormone.
The effect of estradiol-17β (E2)treatment on the pituitary-thyroidal axis has been investigated in female Japanese eels in seawater. The eels were injected with 1 mg/kg body weight (BW)weekly for two to eight weeks; another group was treated with 5 mg/kg BW weekly for eight weeks and sacrificed three days after the last injection. In the pituitary, using RT-PCR system, the thyroid stimulating hormone β subunit mRNA (TSHβ mRNA) level is slowly increased in the low-dose E2 treatment group. A significant increase in values occurred after eight weeks E2 injections. The histological structure of the thyroid follicles suggests a hypo-activity as shown by a reduced epithelial cell height in eels injected with E2 after six and eight times, and eventually reached a minimum level after eight weeks. Using radioimmunoassay of thyroxine (T4), triiodothyronine (T3) in the serum, a slowly decrease of both hormones is demonstrated. On the other hand, the TSHβ mRNA level is significantly increased from initial in the high-dose E2 treatment group. The histological structure of the thyroid follicles suggests a hypoactivity, and a sharp decrease of the both hormones is also indicated. These data suggest that the expression of TSHβ mRNA level is increased and thyroid hormone release is depressed by E2, the effects depend upon E2 injection period and dose. Furthermore, E2 could not directly influence the TSHβ mRNA expression and, TSH transcription might be controlled by a negative feedback of thyroid hormone.
2001, (4): 597-605.
Abstract:
The distributions of the wave-induced radiation stress tensor over depth are studied by using the linear wave theory, which are divided into three regions, i.e., above the mean water level, below the wave trough level, and between these two levels. The computational expressions of the wave-induced radiation stress tensor at the arbitrary wave angle are established by means of the Eulerian coordinate transformation, and the asymptotic forms for deep and shallow water are also presented. The vertical variations of a 30° incident wave-induced radiation stress tensor in deep water, intermediate water and shallow water are calculated respectively. The following conclusions are obtained from computations.The wave-induced radiation stress tensor below the wave trough level is induced by the water wave particle velocities only, whereas both the water wave particle velocities and the wave pressure contribute to the tensor above the wave trough level. The vertical variations of the wave-induced radiation stress tensor are influenced substantially by the velocity component in the direction of wave propagation. The distributions of the wave-induced radiation stress tensor over depth are nonuniform and the proportion of the tensor below the wave trough level becomes considerable in the shallow water. From the water surface to the seabed, the reversed variations occur for the predominant tensor components.
The distributions of the wave-induced radiation stress tensor over depth are studied by using the linear wave theory, which are divided into three regions, i.e., above the mean water level, below the wave trough level, and between these two levels. The computational expressions of the wave-induced radiation stress tensor at the arbitrary wave angle are established by means of the Eulerian coordinate transformation, and the asymptotic forms for deep and shallow water are also presented. The vertical variations of a 30° incident wave-induced radiation stress tensor in deep water, intermediate water and shallow water are calculated respectively. The following conclusions are obtained from computations.The wave-induced radiation stress tensor below the wave trough level is induced by the water wave particle velocities only, whereas both the water wave particle velocities and the wave pressure contribute to the tensor above the wave trough level. The vertical variations of the wave-induced radiation stress tensor are influenced substantially by the velocity component in the direction of wave propagation. The distributions of the wave-induced radiation stress tensor over depth are nonuniform and the proportion of the tensor below the wave trough level becomes considerable in the shallow water. From the water surface to the seabed, the reversed variations occur for the predominant tensor components.
