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Typhoon Rammasun was the strongest typhoon that hit the South China in the past 41 years since 1973. It increased rapidly over the South China Sea (SCS) before the landfall. In early summer, the SCS is warm enough to support the increase of a typhoon in every year. However, the Western Pacific Subtropical High (WPSH) which steers the trajectories of tropical storms in the western Pacific deviates most tropical storms from the SCS. But, recently, the WPSH experiences a westward extension. Analysis shows that WPSH in early summer of 2014 took a more southward and more westward position than it did in the past several decades. As a result, Typhoon Rammasun was guided into the SCS through Philippine, which was an uncommon tropical storm track in July. In the SCS, Typhoon Rammasun was nourished by the warm ocean and became a super typhoon within only 26 hours. As the implication of this study, if the westward extension of WPSH remains and continues, it is reasonable to expect that more tropical storms enter the warm SCS and get intensified in early summer. Consequently, the South China is likely to be more vulnerable to devastating typhoons.

The effective elastic thickness(T_e) which depends on the deep lithospheric temperature structure and crustal compositions, represents the lithospheric ability to resist deformation. The Ninetyeast Ridge(NER), one of the longest seamount in the world, has been studied by many researchers over its original and process. However, the complicated tectonic activities cause that it is too difficult to uncover the evolution of the NER. Here we investigated the NER in terms of T_e with convolution method and obtained its spatial variations of T_e. The results show that values vary from 0 to 35 km. T_e is characterized as high value (averaging 20 km) in the north section (8°N~1°N), low value (averaging less than 5 km) in the middle part (1°N~15°S) and high value (averaging 30 km) in the south section (15°S~30°S), which are associated with three stages of volcanic activities of Kerguelen hotspot. In addition, the variations of values reflect the adjustment of relative position between Southeast Indian Ridge and hot spot during the evolution of NER and further prove that the NER is influenced and controlled by the Kerguelen hotspot, Indian plate's drift and Southeast Indian Ridge's jump. Finally, by combining with the evidence of ROYER's plate reconstruction, a model was proposed to show the evolution of Ninetyeast Ridge.

The distribution characteristics of ∑REE in the bottom sediments are influenced by many factors, so they are too difficult to analyze quantitatively. From qualitative analysis of the relationship between ∑REE content and its provenance, hydrodynamics, grain size and mineral distribution in Beibu Gulf, it is revealed that the main ∑REE composition is controlled by terrestrial rock. Both weaker hydrodynamics and the finer grain lead to the higher ∑REE content. Combined with the quantitative analysis of BP neural network which trained by the position of samples, gravel content, sand content, silt content, clay content and clay mineral content, the relative curves of individual impact factor with ∑REE content were achieved. These relative curves reveal the relationship between the ∑REE content and various impact factors, and the results are consistent with those of qualitative analysis. The method can study by itself, determine automatically and calculate quantitatively. It is helpful for identification of the impact related to each factor and ∑REE and to know how it is controlled the ∑REE distribution. So according to the curve variation and actual situation, environmental changes and geological evolution of the region can be inferred. This also provides a useful theoretical guidance for the analysis of the enrichment and dispersion for the rare earth elements.

Development potential assessment of land resource plays foundation for land use planning. Therefore, finding out the land potentiality of economic production capacity is a key proposition of allotting land resource in the background of urbanization and industrialization. In this study, the index system was established based on natural condition, ecological sensitivity, economic development and spatial structure, moreover, fuzzy comprehensive evaluation and analytic network process method were adopted respectively to value each index and weight. This study figured out potential value by map algebra in ArcGIS and divided study area into four potential districts with natural break method. The conclusions show that: (1) low potential district has the area of 237.14 km², taking the percentage of 17.73%; medium potential district has the area of 323.08 km², taking the percentage of 24.15%; high potential district has the area of 473.34 km², taking the percentage of 35.38% and extreme high potential district has the area of 304.27 km², taking the percentage of 22.74% respectively. (2) According to the analysis of land use types in different land potential districts, transport land and natural reserved land area reach the peak in extreme high potential district and decrease from the extreme high potential district to the low potential district; cropland, rural-urban construction land, other agricultural land and other construction land have the biggest ratio in the high potential district and mostly distribute in the extreme high or the high potential district; garden plot, water surface and water conservancy land are basically distribute in the medium potential district, while tidal flat and woodland distribute in the medium and low potential district.(3) Land development potential in coastal zone of these cities have different characteristics, which are specified as: the potential district in Yuyao county belongs to further-promotion type, the potential district in Cixi county belongs to balance development type and the potential district in Zhenhai belongs to high potential quality type.

Eight uninhabited islands of Sixteen Door are located in the Zhoushan sea area with a high-intensity development. Base on the bathymetric data of 1962, 2002 and 2012, GIS technology was applied to analyze the beach scouring and silting in this region. The results indicate that in the past 40 years from 1962 to 2002, the sediment had been silted up in the study area with the rate of 5.3 cm/a. However, it presents an adjustment from slow silting to rapid scouring in the recent decade from 2002 to 2012, with the annual erosion rate of 52.7 cm/a. According to the analysis, since 2002, the combined effects of the intensive human activities in the study area and its vicinity are the main reason for rapid sediment erosion of the underwater slope.

The coastline information of Bohai Rim in the year of 1980, 1990, 2000 and 2010 was extracted using remote sensing images of Landsat MSS, TM and ETM+ and GIS techniques, and the fractal dimension of the coastline was calculated by box-counting method. The characteristics of spatial-temporal variations of the coastline's length and the driving forces of coastline changes were assessed, and the relationship between the coastal development activities on various scales and fractal dimension changes were also discussed. The results showed that during the research period, the coastline length of the study area increased by 1 074.35 km and the rising intensity increased progressively. The coastline length entered a period of rapid growth after 2000. The most significant change of coastline length was found in Bohai Bay. During the study period, the coastline mainly expanded to the sea. Human development activities were the leading factor for coast change. Before 2000, coastal development was predominantly constituted by reclamation of aquaculture and salt fields; while after 2000, factors causing coastal change tended to become diversified and rates of harbor construction and construction lands increased. The fractal dimension of the overall coastline was increased steadily, indicating that the geometry of the coastline of the study area became more complex. The magnitude and variations of fractal dimension were directly related to material composition and evolution process in the coastal zone. A large numbers of coastal engineering construction of various scales were the leading factor in fractal dimension variation.

The effects of cleaning dredged materials on the growth of two marine microalgae species with different initial cell density:Skeletonema costatum and Heterosigma akashiwo, were investigated by using the measures of experimental ecology. The results show that at the unialgal culture medium of cleaning dredged materials in laboratory, the different initial cell density has apparent effects on the growth of microalgae. At the initial cell density of 0.2×10⁴ cells·mL^-1, the time of entering exponential phase and stationary phase can be extended, and reaching the maximum cell density is higher; at the initial cell density of 0.8×10⁴ cells·mL^-1, the time of entering exponential phase and stationary phase could be shortened, and reaching the maximum cell density is reduced. For the mixed cleaning dredged materials culture medium, the different initial cell density has apparent effects on the relation of interspecific competition between two species of microalgae. There is obvious interspecific competition between S. costatum and H. akashiwo. H. akashiwo has predominance in this competition, and S. costatum suffers from H. Akashiwo inhibition, within the entire experimental period, cell density reduces very significantly and is lower than that in the unialgal culture, while H. akashiwo cell density is not significantly reduced. Among these three different medium concentrations of cleaning dredged materials, the cell density in the highest culture medium concentrations of 1 000 mg·L^-1 is significantly lower than those in 100 mg·L^-1 and 500 mg·L^-1 culture medium, and the cell density is the highest in 100 mg·L^-1 culture medium. This indicates that the greater of clean dredged materials concentrations, the greater effects on the growth of microalgae, while the lower of clean dredged materials concentrations, the smaller effects on the growth of microalgae.

In this study, acute and sub-acute experiments were conducted to elucidate the toxic effect of cadmium on Portunus trituberculatus. The results show that the median lethal dose of cadmium are 6.55, 4.33 and 3.12 mg/L for 48 h,72 h and 96 h respectively, and the safe concentration of this metal is 0.31 mg/L. As the extension of exposure time, the expressions of HSP70 in hepatopancreas and gill are increased at the beginning, and then decreased significantly under the safe concentration and fishery water quality standard. Compared with control group, the expression of HSP70 in gill is more obvious than that in hepatopancreas. Under the safe concentration, the survival rate of Portunus trituberculatus is not changed obviously, but the excessive expression of HSP70 reflects that the crab is stressed by Cd²⁺ exposure, so HSP70 indicators can be reflected more sensitive than the median lethal concentration at low concentration of Cd²⁺ pollution.

A dynamics response model are established using hydrodynamic analysis software OrcaFlex and referring to cable cross section design of Wenchang umbilical cable and operation environmental parameters to simulate the dynamic response of J-tube pull-in installation of the main platform for the umbilical cable under different wave directions. Finally, some instructive notices and mechanical properties during umbilical tie-back were put forward based on related modeling results. The hydrodynamic analytical result shows that the speed of the winch and the change of wave directions have very important effects on the process of umbilical cable pull-in through J-tube; the position where umbilical cable bends badly is where the von mises stress changes obviously as well, but the stress is still less than that permitted by API 2RD, and it can satisfy the request by the engineering safety.

The net-collected phytoplankton community and physicochemical properties of the waters nearby Zhoushan Islands during summer and autumn of 2014 were investigated. A total of 6 phyla, including 92 genera and 184 species were indentified, of which 127 diatom and 30 dinoflagellat species were found in this survey area. The species Skeletonema spp. is dominant in summer, while the dominant species in autumn consists of nine diatom species (i.e., Coscinodiscus jonesianus, Coscinodiscus oculus-iridis, Coscinodiscus argus, Coscinodiscus asteromphalus, Skeletonema spp., Pseudo-nitzschia pungens, Chaetoceros decipiens, Thalassiothrix frauenfeldii and Frustulia interposita). The phytoplankton abundance in summer (1 713.58×10⁴ ind/m³) is higher than that in autumn (1 430.30×10⁴ ind/m³). According to the results of Redundancy Analysis, the temperature, salinity, suspended particulate matter, dissolved inorganic phosphorus and nitrogen are the main environmental factors affected on the phytoplankton community in summer and autumn. Based on the analysis of the integrated historical data, the eutrophication index at the research area has increased clearly since 1996, and the structure of phytoplankton community has also changed significantly. It reflects on the cells abundance increase and the dominant species substitution.

Undisturbed sediment samples were collected from the cage culture zone and nearby of large yellow croaker' farm in Xiangshan Bay in May, Aug. and Nov. of 2013. Total organic nitrogen (TON), total organic carbon (TOC) and total phosphorus (TP) in the sediments were determined. A simulated experiment was conducted to study the sediment oxygen consumption (SOCs) rates and nutrients(NH⁺₄、NO^-₂+NO^-₃、PO^3-₄) fluxes between water column and sediments. TON and TP values of sediment in cage-zone(YZ) are generally significantly higher than those in stations of 50 m away (F1) and 100 m away (F2) (P<0.05). The sediments release NH⁺₄ to the overlying water where as they takes up NO^-₂+NO^-₃ and PO^3-₄. Benthic fluxes show that intensive seasonal variations and the release of NH⁺₄and PO^3- ₄reach peak values in August, which response to increased organic input due to the yellow croaker farming. The nutrient concentration in water changes with benthic nutrient fluxes among seasons. The results obtained in this study imply that the ongoing aquaculture activities have led to sediment organic pollution at certain extent and the polluted sediment could affect the benthic nutrient fluxes, which might cause the redistribution of nutrients in water column.