Wind not only drives the surface ocean circulations, but also provides the main source of kinetic energy for deep ocean movements. This study focuses on the wind energy input to the north part of the North Pacific, including wind energy input to surface wave, surface geostrophic currents and surface ageostrophic currents. Results based on SODA3 (2000–2016) data show that there are obvious seasonal wind energy input gateways, which are the Subpolar Gyre for spring and autumn, the Eastern Pacific for summer and the Kuroshio Extension for winter respectively. The winter gateway gains the most wind energy among the four seasonal gateways, which is about 3−5 times higher than others. Since the beginning of the 21st century, wind energy input in winter gateway has weakened significantly, while increased in spring gateway, but has not changed significantly in summer and autumn gateway. For the spatial distribution of the trend in the 17 years, wind energy input to the surface wave is mainly dominated by the wind field, while wind energy input to the surface geostrophic current and ageostrophic current is dominated by the flow field. These mechanical energy input results are important for further understanding the ocean circulations in the North Pacific.

A series of laboratory experiments is carried out in a wave flume to study the influence of rough reef surface on solitary wave transformation and run-up over coral reefs. The cylinder array is used to model the reef surface with large roughness. The results show that the rough reef surface significantly reduces the leading solitary wave and the secondary wave due to beach-reef beach reflection, as well as the wave speed on the reef flat. The relative cross-shore wave height decreases with the increase of dimensionless incident wave height along the reef. It also increases with the increase of reef-flat wave level. The cross-shore wave height attenuation is more evident with the rough reef surface. The variation of dimensionless reflected wave height with the dimensionless incident wave height depends on the reef-flat wave level. The dimensionless reflected wave height approaches to a constant when the incident wave height is sufficient large. The rough reef surface slightly enhances the wave reflection from the fore-reef slope. The dimensionless transmitted wave height as well as wave run-up decline with the increasing dimensionless incident wave height, particularly for the large reef-flat water level. The dimensionless wave run-up on the back-reef beach with the rough reef surface reduces by an average of 46% compared to that with the smooth surface. An empirical formula is obtained by a regression analysis to predict the wave run-up with both smooth and rough reefs.

In order to study the wave characteristics in the Sanmen Bay, field observation based on AWAC data acquisition equipment was continued for one year, and the statistical analysis, linear regression analysis was done. Moreover, statistics and spectral variations of waves during the typhoon occurrence were investigated, and the reason for the variations was determined on the basis of wave data collected. The results show that the dominant wave direction and the strong wave direction are both E due to the topography of coastal areas; during the wave observation period, H_1/10 is mainly under 0.8 m, and H_max is 2.71 m; the distribution of wave characteristics is a typical Rayleigh distribution in this region; the wave spectra estimated during Typhoon Talim is double-peaked, and the total wave is a combination of swell and wind sea, when the low frequency swell about 0.08 Hz is in a dominant position and the high frequency wind sea about 0.25 Hz is relatively weak. This study will be important as reference in the design of offshore structures as well as for disaster prevention and mitigation.

Grain size, clay minerals and major and trace elements of surface sediment samples collected from the East Siberian Arctic Shelf are analyzed. Based on factor analysis and cluster analysis the study area is divided into four provinces, the main sediment sources of each province are discussed. The results show that province I covers the estuary area of the Kolyma River and the Indigirka River. The sediments are mainly composed of silt and sandy silt, and characterized by higher content of SiO₂, TiO₂, Zr and low content of other elements. The ratios of La/Th and Zr/Hf reach the maximum in the four sedimentary areas. Illite is dominant which accounting for 70% of the whole clay minerals. This area is strongly influenced by terrestrial sources from the Kolyma River and the Indigirka River. Province II is located in the middle of the East Siberian Sea, where the sediments are generally silt and mud. The content of MnO, Ba, and Ni are relatively higher. La/Th and Zr/Hf ratio are slightly lower than that in Province I. Clay minerals composition is similar to Province I. The sediments in this area are mainly fine-grained derived by rivers, which are also influenced by sea ice process. As the distance increasing offshore, the content of marine authigenic components begin to increase. Province III is located in the northern East Siberian Sea, and sediments there are mainly mud. Elements such as Al₂O₃, K₂O, V, Li reach the maximum value in this area. The La/Th and Rb/Th ratios are similar to those in the Province II. The content of illite is the lowest, semctite and kaolinite reach the maximum (>10%). Fine-grained sediments in this area are probably influenced by Atlantic waters and the Beaufort Gyre. Province IV is located in Chukchi Sea where the sediments consist of silt and sandy silt. Elements are characterized by higher contents of CaO, P₂O₅. The ratios of Rb/Th, La/Th and Zr/Hf are the minimum values, the content of chlorite reach peak (>20%). Sediments in this area are significantly influenced by the Pacific inflow water.

Paleoproductivity and environmental evolution since 34 ka BP in the southeastern Scotia Sea, Antarctica were reconstructed by the chronological analyses of biogenic opal (BSiO₂), organic nitrogen (N_org), TFe₂O₃ and organic nitrogen isotopes (δ¹⁵N_org) in Core DC-11. Changes in BSiO₂ and N_org contents are basically consistent with the Antarctic temperature, being higher in warm times. δ¹⁵N_org is coincident with the Antarctic sea ice, being greater and reflecting enhanced nitrate utilization in surface water during cold periods. From Last Glacial, Last Deglaciation to Holocene, paleoproductivity and environment changed significantly, and the millennial variability such as the Antarctic Cold Reversal (ACR) is prominent in the study area. Sea ice plays an important role in correlations between the climate, nutrients and paleoproductivity. The increase of sea ice during the glacial or cold periods caused stronger stratification of surface waters, weaker upwelling of deep waters and their dissolved nutrients to the surface ocean, and then resulted in enhanced nitrate utilization and lower paleoproductivity in surface water. Iron supply in the study area is sufficient in present-day and Holocene while it is excessive during Last Glacial and Last Deglaciation due to more developed dust, which is obviously different from that in the Subantarctic Zone.

Storm surge is a complex ocean phenomenon which is sensitive to many factors and has attracted much attention. In this paper, based on covariance localization method of ensemble Kalman filter(EnKF), the storm surge data of different sources, different error and different spatial and temporal resolution calculated by tide gauge stations and FVCOM model were assimilated and fused for the first time. Taking the storm surge process of typhoon 201810 landing in Shanghai for example, the optimal solution of 72-hourly storm surge in the Shanghai offshore areas was obtained and verified, the setting range of set sample number and Schur radius were given. The results show that the root mean square error of storm surge calculated by the observed stations and the model is 0.20 m, while calculated by the observed stations and assimilation is 0.07 m, which is improved by 65%, the root mean square error calculated by independent observation and assimilation is 0.09 m, the ratio of set dispersion to root mean square error is 0.90, the assimilation effect is better and credible. The assimilated storm water increment field can clearly and accurately depict the characteristics of double peaks storm surge, typhone eye surge and frontal surge which can be better used for the research of storm surge, correction of numerical simulation and marine disaster prevention.

In this study, elemental and mineral compositions of three surface sediments collected from the South Atlantic Ridge affected by hydrothermal activities of various degrees were analyzed, and series of extraction experiments for carbonate phase, Fe-Mn oxide phase and insoluble residual phase were carried out. Mixed reagent of hydroxylamine hydrochloride (HH) with different concentrations and 25% acetic acid (HAc) were used to extract Fe-Mn oxide phase from the sample. In order to corroborate the reliability of the extracting methods, Ti/Nd and Ti/Pb ratios of the Fe-Mn oxide phase, rare earth elements (REE) patterns as well as δCe and δEu ratios of different chemical phase were used to determine that the ideal reagent conditions for extracting Fe-Mn oxide phase from three different types of hydrothermal sediments were all 0.5 mol/L HH in 25% acetic acid. The results show that the higher the degree of influence of hydrothermal activities, the higher the contents of Fe, Cu, Zn and other elements in the sediments, and the contents of Ca, Sr and Ba show an opposite trend. Manganese, Pb and REE are not significantly affected by hydrothermal activities. As the influence of hydrothermal activity increases, the proportion of Ca, Sr and Nd increases in the Fe-Mn oxide phase and decreases in the residual phase, while Mn, Co, Ni and Zn have an opposite trend, and the proportion of Cu increases in the carbonate phase and decreases in the residual phase. Lead is not affected by the influence strength of hydrothermal activity and mainly occurs in the Fe-Mn oxide phase. REE mainly occur in the residue state. The occurrence state of REE shows that the more significant influence by the hydrothermal activities of the sediments, the more enrichment of REE in the residual phase. And the chondrite-normalized REE patterns of the residual phase exhibit that the enrichment of light REE are less obvious. This study provides methods for extracting hydrothermal fractions and valuable geochemical data for further understanding of the characteristics of hydrothermal sediments and the effects of hydrothermal activities on the occurrence state of elements in the South Atlantic Ridge.

It is of great significance to quickly acquire spatiotemporal change in the information of waterline of remote sensing image. The extraction of the waterline of tidal flat on the remote sensing image has always been a difficult problem in the application of remote sensing technology. There are unique spatial relationships and spectral characteristics on the remote sensing image of waterline. The research area is the Chongming Dongtan of the Changjiang River Estuary. By integrating methods of color model transformation, information entropy calculation, maximum variance and edge detection, we explored how to enhance the contrast of land and sea on the Landsat-5 satellite image, and the edge extraction at different scales was studied. The calculation method of the spatial and spectral characteristics of the waterline using the thermal infrared band was given. A fast extraction method of waterline of sensory image taking the spatial relationship and spectral characteristics into account under the framework of object-oriented technology was proposed. Results show that: (1) The local threshold segmentation method based on the maximum between-class variance method can automatically extract the waterline of band 6. The waterline is continuous, complete, and rich in spatial information. (2) The combination of the optimum index factor method, the dispersion method and the color model transformation method can effectively enhance the contrast between land and sea. The local adaptive Canny operator based on the maximum between-class variance method can automatically detect the high precision edge of the enhanced remote sensing image. (3) Using the spatial relationship and spectral characteristic of waterline, the computer can recognize and connect waterline automatically. (4) The waterline extraction method proposed in this paper is fast and automated, inheriting strong continuity of the threshold segmentation method and high positioning accuracy and strong ability to present details of Canny operator. The results have significant value for researches on the dynamic changes in the coastal zone, the mechanism of land-sea interaction, the protection and development of coastal zone resources, and offshore engineering management.

In this study, the population genetic diversity and structure of Parasesarma affine in the South China Sea were analyzed based on 222 individuals of twelve populations using Cytochrome Oxidase Ⅰ (COⅠ) sequence. A 612 bp fragment of COⅠ gene were sequenced, from which 34 polymorphic sites were tested and 40 haplotypes were defined. The most frequent haplotype was Hap2 with the highest frequency of 69.81%, which was shared in all twelve populations. Total haplotype diversity (H_d) and nucleotide diversity (P_i) were 0.508 9, 0.001 126, respectively, which represented a moderate level of haplotype diversity and a low level of nucleotide diversity. No clustering corresponding to sampling localities was found in neighbor-joining tree and haplotype network. The genetic distance ranged from 0.000 36 to 0.001 73 within populations and from 0.000 48 to 0.001 72 between populations. Genetic fixation index (F_st) and analysis of molecular variance (AMOVA) indicated that the genetic variance mainly came from individuals within populations, and a low level of genetic differentiation among twelve populations. Both neutral test and mismatch-distribution analysis implied that the populations of P. affine had a recent population expansion event that occurred in about 51 000 years ago in the late Pleistocene epoch. In summary, the longer time of the planktonic larval phase and the lack of evident geographical barriers in the marine realm might be major reasons for that P. affine could carry out extensive gene flow and possessed a low level of genetic differentiation among all twelve populations. In addition, the severe climate change of pleistocene epoch might also have important effects on the genetic structure and patterns of distribution of P. affine populations. The research results could provide a theoretical basis for the conservation and utilization of P. affine.

The purpose of this study was to investigate the diversity of actinomycetes collected from the Maowei Sea Natural Reserve of Mangrove in Guangxi, and screen the functional enzymes activities from these actinomycetes. Actinobacterial diversity of Mangrove soil was studied by culturable method and phylogenetic analysis based on 16S rRNA gene sequences. Ten enzyme active substrates were selected as indicator reaction. Activity for functional enzymes was tested by inoculating single colony method. Total of 444 strains of culturable actinomycetes were obtained from mangrove soil environment, they were classified into 63 species, 24 genera, 13 families and 6 orders by 16S rRNA gene sequence analysis. The three strains of them was potential new species. Streptomyces sp. was the dominant genus. Among them, 56 strains were screened with at least one or more enzymes activity. The total positive rate was 88.89%. And two enzymes activity at least could be screened from the 31 strains. And the dominant strains capable of enzyme-producing were of Streptomyces sp., Microbacterium sp. and Curtobacterium sp. Our results showed that in the Maowei Sea Natural Reserve of Mangrove soil, there existed a higher diversity of culturable actinomycetes, and there are large numbers of unknown actionobacterial groups here. These actinomycetes have the abilities to produce excellent functional enzymes.