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.

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.

Since 1950, the sediment load of the Changjiang River entering the sea has been stepwise decreasing. As the distal mud of the Changjiang River, whether the signal of “sediment load reduction” was recorded in the Zhe-Min coastal mud? If so, how to extract and interpret these sedimentary information? In order to discussing this scientific problem, 5 sediment cores were collected in the Zhe-Min coastal mud; in addition, high resolution grain size analysis (2 mm) was conducted, and four end members were obtained through end-member (EM) model decomposing. Combined with the analysis of the spatial discrepancy in provenance and hydrodynamics of the study area, the specific indicative significance of each EM was revealed: EM1 (with the modal grain size about 2 μm) is originated from extremely fine-grained sediment of the Changjiang River; EM2’s (with the modal grain size about 10 μm) origin is predominated by the Changjiang River, and small part is contributed by the middle and small sized rivers of Zhe-Min coast; EM3 (with the modal grain size about 80 μm) mainly consists of coarse-grain sediment might be provided by Taiwan Warm Current; EM4 (with the modal grain size about 200 μm) is also characterized by coarse-grain sediment, and may be contributed by the Changjiang River. Further analysis indicated that, the EM1 variation was in agreement with the sediment stepwise reduction of the Changjiang River; however, the response intensity gradually decreased from the north to the south. In addition, the hysteresis existed in response time, and the retardation time increased from 4−6 years in the north to 10−14 years in the south. In general, fine-grained sediment could better reflect the Changjiang River catchment change information, and response intensity exhibited significant difference in different areas of the Zhe-Min coastal mud.

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.

In view of the effect of internal solitary waves on the seafloor when encountering the seabed slope during their travel, the dynamic response of different slopes to internal solitary waves should be different. This paper studies the dynamic response process of internal solitary waves of slopes with different angles by creating internal waves in a flume. The results show that the internal solitary waves passing over the shelf slope will cause the accumulation of excess pore water pressure in the slope sediments; under the same amplitude conditions, the dynamic response amplitude of the gentle slope sediments is larger than that of the steep slope sediments; as the amplitude increases, gentle slopes occur the degree of dynamic damage is greater than that of steep slopes; the accumulation and release of excess pore water pressure exist at the same time before the stability of slope sediments is destroyed, and the increase of the amplitude of internal solitary waves will aggravate the release of excess pore water pressure. The results will play a guiding role in the dynamic study of the failure of slope sediment under the action of internal solitary waves and the analysis of slope stability.

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.

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.

The sediments in the hydrothermal field received a large amount of hydrothermal input, and their mineral compositions and geochemical spatial distribution characteristics are effective indicators for polymetallic sulfide exploration. Due to gravity, sediments in the mid-ocean ridge area are mainly distributed in low-lying and flat terrain areas. In order to explore the influence of topographical factors on the distribution of sediments in the hydrothermal field, this paper proposes a prediction method of sediment distribution trend in seafloor hydrothermal field based on topography data through ArcGIS, and analyzes the topographic data of Dragon Horn area on the Southwest Indian Ridge, including the extraction gravity transport direction of sediment, the estimation of sediment accumulation amount, the extraction of submarine ditch valley and the division of sediment source area. By comparison and verification with the interpretation results of the seafloor camera data of the study area, we found that the prediction results are in good agreement with the actual distribution range of the sediments in the study area, indicating that this method can effectively indicate the distribution of sediments in the submarine hydrothermal field under the influence of terrain to a certain extent. This method has certain guiding significance for the exploration of submarine sulfide minerals, and could provides a reference basis for the setting of sampling stations for seafloor sediments and the delineation of polymetallic sulfide mineralization prospects.

We analyzed δ³⁰Si of dissolved silicate of surface seawater from the Pacific Ocean, Indian Ocean and Atlantic Ocean. The results showed that the δ³⁰Si of the Pacific Ocean surface seawater was 0.45‰−2.91‰, withan average value of (1.52±0.59)‰; the δ³⁰Si of the Indian Ocean surface seawater was 0.98‰−2.30‰, with an average value of (1.52±0.36)‰; the δ³⁰Si value of the Atlantic Ocean surface seawater was 0.90‰−2.23‰, the average value was (1.55±0.35)‰. The silicon isotope in the ocean surface layer mainly shows the correlation with the ocean surface circulation and meridional overturning current, and its distribution characteristics are mainly affected by the biological activities in the surface water and the mixing between different water masses caused by the movement of the surface ocean currents. The mixing effect perhaps has a significant effect on the distribution of δ³⁰Si in the surface water of the open oceans.

Plastics accumulate in the environment and gradually break into microplastics (MPs, size below 5 mm). It poses a serious threat to the environment and human health. In this study, a strain LC-2 capable of degrading polyethylene (PE) was isolated from plastic films collected from the Licun Estuary of Qingdao. It was identified as Bacillus aquimaris by using a combination of molecular biological technique with morphological, physiological and biochemical characteristics. After the strain was isolated, it was cultured in a liquid medium for 28 days with PE as the sole carbon source. The polyethylene was subsequently separated and examined with a scanning electron microscopy, a contact angle test, a thermogravimetric analysis and a Fourier transform infrared spectrum analysis. The results showed that the weight loss of PE was about 9% after the degradation, with apparent morphologic changes on the surface of PE. It was also showed that the hydrophobicity of PE became smaller, with surface oxidation to produce −C=O functional groups. These evidences are sufficient to prove that the strain LC-2 can degrade PE.