Archive

CEOF and wavelet methods were employed to discuss the relationship between the main modes of upper circulation anomalistic field in the North Pacific during winter and the PDO, NPGO modes. The results show that the first and second CEOF modes of the upper circulation anomalies are the reflection of the PDO and NPGO modes on the circulation field. Firstly, the real time coefficients of the first two modes have obvious decadal periods of about 20 and 13 years, respectively, which are the same as the periods of PDO and NPGO modes. Secondly, the regression fields of the first two time coefficients with the SSTA in the North Pacific are quite similar to the spatial feature of PDO and NPGO modes. The distributions of dynamic anomalies of near-surface temperature obtained by the vertical movement of the first two modes of the upper circulation anomalies are similar to those of PDO and NPGO modes. This means that the vertical movement of oceanic flow is the important reason of formation of PDO and NPGO modes.

High wind speed data were obtained by using the angular momentum model and their precision was verified by the weather station recorded data. A wind speed inversion algorithm for altimeter was developed by using these wind speeds. The results show that this new algorithm can inverse the sea surface wind speed more accurately when typhoon passes through, which realizes the high wind speed (10~40 m/s) inversion for altimeter. This, therefore, can be taken as the supplement of altimeter wind inversion algorithm for Jason-1 at the high wind speed, and improve the precision of altimeter wind inversion algorithm.

The processing and prediction of tidal current signal are significant and valuable in various aspects. This study introduced a signal sparse representation theory, constructed a sparse AR model in order to find out the connection among the tidal currents, and to carry out the forecast analysis. Firstly, we established the conventional AR model by measuring current signal, so we could get a set of complete sparse matrix. Secondly, we randomly extracted parts of this to create underdetermined system of equations. We acquired the sparse AR coefficients by using sparse optimization algorithm. After repeating above steps for many times, the stability increased and reached to average sparse AR coefficients. Finally, the last step was to reconstruct or predict the tidal current signal by using the last sparse AR coefficients. By using the measured observations of tidal current, especially the observations with many peaks or rotary current phenomenon. Many experiments had been done to establish the sparse AR model and prediction. Comparing this AR model with flow harmonic method, the sparse AR model is much better than the traditional tidal harmonic method especially in analysing the region with changeable tidal current. Moreover, the variance of the sparse AR model is less than that of the traditional tidal harmonic analysis.

There are three main manganese oxides in polymetallic nodules. They are vernadite、todorokite and birnessite. Different manganese oxides have their specific origins and growth environments. It is found that there is a special opal-layer which is full of todorokite veinlets in the polymetallic nodules from the Eastern Pacific Ocean. Microscope、EPMA (Electron Probe MicroAnalysis) and ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer) methods were used to find out the micro-structure and geochemical features of the opal-layer and its surrounding minerals, in order to investigate the origin of the opal-layer. It shows that: (1) The special opal-layer and its surrounding area are mainly composed of todorokite,vernadite and opal. (2) Todorokite has high reflectivity and Mn/Fe ratio. It is mainly composed of MnO and of diagenetic origin. (3) Vernadite has moderate reflectivity and low Mn/Fe ratio. It is mainly composed of MnO and FeO, it is of hydrogenic origin. (4) Opal has low reflectivity. It is mainly composed of SiO₂ and of biogenic origin. A model was set up for the formation of the opal-layer and the todorokite veinlets inside. It could be divided into 5 stages as follows:(1)In the oxidizing environment, vernadite was formed on the surface of the half-buried nodule.(2) The dissolving of biogenic opaline silica leaded to a vast amount of colloidal silica in the upper water of the seafloor. The colloidal silica deposited on the surface of the half-buried nodule, forming the opal-layer.(3) In the oxidizing environment, vernadite was formed on the surface of the half-buried nodule. At the same time, the diagenesis of the nodule and dehydration of opal led to the formation of cracks in the opal-layer.(4) The nodule was buried by the silica-rich sediments. In the reducing environment, the todorokite veinlets formed in the previous cracks by the invasion of interstitial water from the surrounding sediments.(5) The nodule re-exposured in the water, forming vernadite on its surface in the oxidizing environment.

As one of the major generated place of the Antarctic Bottom Water (AABW), the Weddell Sea is a very important margin sea in Antarctic, its hydrodynamic environmental change and its response has important significance to the global change. Over the past century, the global change characterized by global warming had affected Antarctic and the Southern Ocean. In order to understand the hydrodynamic environmental changes in this region, ²¹⁰Pb dating, grain size parameter and ice-rafted detritus content were analyzed and discussed for a short sediment core of ANT28-D5-6 which was taken in the north of Weddell Sea, south to the South Orkney Islands and east to the Antarctic Peninsula. The results show that the hydrodynamic force of Northern Weddell Sea had significant change in nearly hundred years from 1922 to 2011. During 1922-1972, the Northern Weddell Sea was in a high-energy, high-speed and turbulent hydrodynamic environment, and a large amount of ice raft debris was carried and deposited, which was corresponded well to the relatively low temperature stage of the earth. In the course of them, there were twice hydrodynamic environment weakened events happened during 1930-1936 and 1946-1952. The twice increased events of ice-rafted detritus content in 1939 and 1950 might be related to the longitudinal enhancement of Weddell Gyre, which was caused by 17^th and 18^th Solar Maximum Year. During 1972-2011, the Northern Weddell Sea remained relatively calm and low energy hydrodynamic condition, which was corresponded well to the continual warming up stage of the world. During 1955-1972, it was a rapid transition from the high-energy and turbulent state to the low-energy water dynamic of the Northern Weddell Sea.

Sediment survey was carried out in the tidal sand ridges and troughs west of Taiyangsha Ridge in the southern Yellow Sea. Samples were taken with vibrating piston sampler in dense stations. Based on results of grain size analyses, the space distribution characteristics of the surface and shallow sediments with thickness some 2~3 m were elaborately studied. The results show that fine sands of the surface sediments mainly distribute on the tidal sand ridges and coast beach, while other finer sediment types mainly distribute in tidal troughs, appearing a basic feature of sediment-morphology pattern of “ridge-sand and trough-soil”. Meanwhile, the distribution scope of the surface fine sands on the tidal sand ridges is clearly related to the distance between the ridges and the coast. Apart from the influence of tidal currents, this is mainly due to the wave energy consumption by the outer ridges. Based on the above characteristics of sediment-morphology pattern, evolution of sedimentary environment was also discussed.

The analysis on the coastal landscape pattern evolution has great significance to understand the relationship between human activities and landscape pattern evolution, and to promote the sustainable development of coastal area. Based on the Landsat TM images of 1990, 2000 and 2010, landscape pattern evolution of coastal zone around the Xiangshangang Bay was analyzed by using “3S” techniques. The results showed as follows: (1) The areas of the woodland, the sea and the farmland decreased, while the construction land, water area, aquaculture land and unused land increased, and the area of beach increased at first and then decreased. (2) The patch number (NP), the patch density (PD) increased, the mean patch area (MPS) decreased, the perimeter density (ED) and the shape index (LSI) increased, Shannon's diversity index (SHDI) and Shannon's evenness index (SHEI) increased, and the landscape heterogeneity increased. (3) The whole dynamic degree showed a rising trend, and the landscape of coastal zone around the Xiangshangang Bay changed more frequently because of human activities intensity about development and utilization. (4) Human activities and natural factors led to the landscape pattern evolution of coastal zone around the Xiangshangang Bay.

Using interferometric principle, GeoSwath Interferometric sonar can get bathymetry data and side scan sonar image. There are some differences between the interferometric systems and traditional side-scan sonar. The GeoSwath Plus System 125 kHz was compared with Klein System 3000 in their theory, technical specification, software and test data. The results show that these two systems are different in types of the acquisition data, which leads to the difference in their purpose. The GeoSwath Plus System is more complex, but its applicable depth is shallower. The kinds of acquisition software which can be used in GeoSwath Plus are less, and its post-processing softwares are required more powerful. But there are more choices for Klein System 3000 in its acquisition and post-processing software. It is found by compared the measured data that the position of GeoSwath Plus image is more accuracy, but the quality and resolution of its sonar image are worse than those from Klein System 3000 because of bigger beam horizontal angle and hanging installation.

Nano-SnO₂ photocatalyst was obtained by the chemical precipitation method with SnCl₄·5H₂O as the raw material. The particle size of powders, object and morphology have been characterized using the X-ray diffraction and electron microscope. The photocatalytic degradation of ammonia nitrogen in aquaculture wastewater was investigated by using our home-made nano-SnO₂. The effects of different degradation variables on the degradation efficiency were investigated, and the results show that nano-SnO₂ catalyst dosage, the initial mass concentration of ammonia-N in wastewater, pH value, the mass concentration of H₂O₂ are the main effect factors. The optimum reaction conditions are as follows: nano-SnO₂ catalyst dosage is 1.2 g/L, the initial concentration of ammonia-N is 20 mg/L, pH value is 8.0, reaction time is 2 hours and H₂O₂ concentration is 1.0 g/L. Under such condition, the removal rate of ammonia-N can nearly reach 72%.

Phasolosma esculenta is a peculiar edible marine economic species in China. In this study, the antimicrobial effect and physical and chemical characteristics of coelomic fluid extracted from Phasolosma esculenta was examined with agar diffusion and plate counting method. The result shows that this fluid is found to have an antibacterial activity against three G⁺ bacteria (Staphylococcus aureus, etc), but has no obvious antibacterial activity against three G^- bacteria (Escherichia coli, etc) and the yeast Candida lusitaniae. Results also show that: (1) Different extraction procedure shows different antibacterial activity. Three extraction procedures are compared: (a) the coelomic fluid without any treatment; (b) with ultra sonication and (c) mixed with 2% acetic acid. Pretreated with an ultra-sonication step, the extract has the best antibacterial effect. (2) The antibacterial activity of this component is effective up to 90 minutes and freezing-resistant. With its optimal temperature of 25 ℃, it shows an antibacterial effect within temperature ranging from 5 to 30 ℃. The fluid is inactivated with water bath treatment at 60 ℃ for 10 minutes. In addition, the antibacterial activity is independent from the metal ions. (3) Moreover, by separating fluid components based on molecular weights, it shows that the effective component is larger than 100 kDa.

In order to provide the theory basis for the scientific control of dissolved oxygen in the process of transportation and culture for juvenile fish, the oxygen consumption rate and the suffocation point of the juveniles for five species of mariculture fish (Plectropomus leopardus、Cromileptes altivelis、Epinephelus fuscoguttatus、Epinephelus akaara and the hybrid of Epinephelus Lanceolatus ♂×Epinephelus fuscoguttatus♀) of which weight ranged from 53.6 g to 84.5 g under the condition of different temperature(20 ℃, 25 ℃and 30 ℃) were investigated using closed breathing experimental method. The results show that both the oxygen consumption rate and the suffocation point of the juveniles for five species of mariculture fish increase with increasing water temperature under the salinity condition of 30 degree. The oxygen consumption rates of Plectropomus leopardus are the highest, which are 0.15 mg/(g·h), 0.21 mg/(g·h) and 0.31 mg/(g·h) at the water temperature 20 ℃, 25 ℃ and 30 ℃ respectively, while the oxygen consumption rates of the hybrid of Epinephelus Lanceolatus ♂×Epinephelus fuscoguttatus♀ are the lowest, which are 0.08 mg/(g·h), 0.15 mg/(g·h) and 0.16 mg/(g·h) at the same water temperature. The suffocation points of Cromileptes altivelis are the highest, they are 1.00 mg/L, 1.12 mg/L and 1.21 mg/L at the water temperature 20 ℃, 25 ℃ and 30 ℃ respectively, while the suffocation points of the hybrid of Epinephelus Lanceolatus ♂×Epinephelus fuscoguttatus♀ are the lowest, they are 0.19 mg/L, 0.24 mg/L and 0.25 mg/L at the water temperature 20 ℃, 25 ℃ and 30 ℃ respectively.

Primary productivities and features of the phytoplankton composition in the nearshore waters of Tianjin from 2012 to 2013 were studied. In spring, the primary productivities were 2.20 to 23.18 mgC/(m²·d), and the average value was 9.54 mgC/(m²·d), while in summer, the primary productivities were 6.37 to 138.37 mgC/(m²·d), and the average value was 44.13 mgC/(m²·d), which were lower than those from 1982 to 1983 and from 1992 to 1993. The horizontal distribution of primary productivities in Tanggu was higher in spring, while those in Beitang and Hangu were higher in summer. Total 2 phyla including 59 species of phytoplankton were commonly found in the survey area, in which 83.1% were diatoms and 16.9% were dinoflagellates. The dominant species were Rhizosolenia delicatula, Ditylum brightwellii, Bidduiphia sinensis, Skeletonema costatum, Chaetoceros curvisetus, Nitzschia pungens, Leptocylindrus danicus and Eucampia zoodiacus. Phytoplankton cell abundance from 2012 to 2013 was from 3.32×10³ to 3.85×10⁷ cell/m³ in spring and 2.48×10⁶ to 4.65×10⁹ cell/m³ in summer, which was higher than that in spring clearly. The horizontal distribution of phytoplankton cell abundance in north and south of Tianjin nearshore waters was higher than that in the middle, which was due to the river distribution. Shannon-Wiener index of phytoplankton community average value was 1.865 in spring and 1.560 in summer. Features of the phytoplankton community form 2012 to 2013 were mainly influenced by depth, COD, pH, DO and phosphorus.