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Subaqueous debris flows are widely developed on polar continental margins, many of which are glacigenic, representing the products of ice sheets reaching the shelf edge. In the western Arctic Ocean, a large number of debris flows have been identified at the continental margin west of the Northwind Basin, however research on debris flows within this basin has hardly been carried out. In this study, the distribution of debris flows was outlined and their formation ages were determined using the high-resolution sub-bottom profiler data. Then the mega-scale glacial lineations (MSGL) was used as the judgment indicators to infer the origin of these debris flows. It is found that the debris flows in the study area are mainly distributed on the southwestern and northern-central slope of the western sub-basin, in the southeastern part of the eastern sub-basin, and on the slopes of some seamounts and cliffs. They are from the surrounding continental shelf, ridges and seamounts. Most debris flows coexist with MSGL and are presumed to be glacigenic. More than 9 glacigenic debris flows have been found on the southwestern slope, which may indicate more than 9 ice streams advances through the Broad Bathymetric Trough. The number of ice streams advances are much more than the previous speculation (3-5). There are also some debris flows with no ice-grounding landforms (e.g. MSGL) have been found in the nearby seamounts and are presumed to be non-glacigenic. The shock caused by the grounding of the ice sheets/shelves in the nearby area or tectonic movement may be the trigger factors for this kind of debris flows.

Using Argo measured data combined with satellite remote sensing data and moored buoy data, the upper ocean temperature and salinity response caused by super typhoon Rammasun in 2014 was analyzed and studied. The result shows that super typhoon Rammasun resulted in cooling of sea surface temperature and deepening of mixing layer. Meanwhile, mixing length and vertical velocity induced by typhoon were calculated in this research, which explained the causes of temperature changes in the subsurface layer. Strong mixing and weak upwelling led to warming of the subsurface layer, whereas weak mixing and strong upwelling led to cooling of the subsurface layer. Compared with the change of temperature, the response of salinity was more complex. Precipitation first caused the decrease of surface salinity, and then vertical mixing led to a large increase of surface salinity. However, the effect of precipitation could greatly inhibit this process. After the typhoon departed, the vertical mixing was weakened, and the salinity was greatly reduced because of the heavy precipitation, it was even lower than that before the typhoon.

Wave is an important factor to shape the dynamic geomorphology of the open tidal flat, but researches on tidal-flat wave characteristics are still limited. Taking Nanhui tidal flats in the Changjiang Estuary as an example, the wave characteristic parameters and wave spectrum parameters were obtained by inverting flow-velocity and water-pressure data from the Acoustic Doppler Velocimeters (ADVs) at some fixed platforms, and their changes over tidal cycles and associated influence mechanisms were discussed. The results show that both normal wave direction and prominent wave direction at three stations of Nanhui tidal flats are mainly southeast during the observation period, with long-period swells dominating. The effective wave height of the three stations is positively correlated with the water depth, but the fitting coefficients of each station are different over flood and ebb periods. Wave orbital velocities are obviously modulated by the shallow water effect and the flow directions, and their maximum values usually occur at the early flooding stage, while minimum values can be observed to occur during the current transition periods. The wave energy spectrum during ebb tides is featured by the bimodal pattern because of high influence by tidal levels and coastal topography, and the peak energy is continuously attenuated and gradually dispersed with the concurrent shift of peak frequencies.

With the advancement of observation technology and the improvement of ocean numerical simulation capabilities, some stable subsurface coherent vortices have been widely observed in the ocean, which far from the formation source area. These vortices possess distinctive dynamic characteristics, such as a low potential vorticity center, lens-like structure of isopycnals, weak stratification, and anomalous temperature, salinity, or other tracer properties compared to the surrounding water mass. Their core flow is relatively stronger. These subsurface coherent vortices significantly impact ocean water mass transport, thermohaline circulation and marine biological environment. This paper comprehensively summarizes researches on subsurface coherent vortices in the ocean, including their structure, hydrological characteristics, identifying methods, global distribution, dynamic mechanisms and their important effects on ocean environment. Furthermore, the research perspectives are discussed, such as the difficulties in the research and the issues that need to be solved to comprehensively understand subsurface coherent vortices in the ocean.

Oujiang River is a typical mountain river whose water and sediment fluxes are characterized by a great disparity between flood and dry seasons. Based on the measured data of water discharge and sediment load at the mainstream control hydrological station of Oujiang River in the past 71 years (1950—2020) and 43 years (1956—1998), respectively, the coefficient of nonuniformity, Mann-Kendall non-parametric statistical test and double mass curve were used to analyze the variations of runoff and sediment load during the flood seasons (including plum rain season from April to June and typhoon season from July to September) and dry seasons (non-flooding season from October to March in next year) in the Oujiang River. The results showed that: (1) The peak and valley month of runoff were the same as sediment load. The peak month of both runoff and sediment load appeared in June, while their valley month appeared in December. The plum rain season was the most important period of water and sediment transporting to sea from Oujiang River. (2) The runoff showed significant decreasing trend in the plum rain season, significant increasing trend in non-flooding season, and non-significant trend in typhoon season during 1950—2020 in Oujiang River. The nonuniformity of intra-annual distribution for runoff had become more uniform obviously, resulting from the regulation of reservoirs. (3) The sediment load showed significant decreasing trend in the plum rain season due to the interception of reservoirs, and no significant trend in typhoon season and non-flooding season during 1956—1998 in Oujiang River. The nonuniformity of intra-annual distribution for sediment load showed little change, which might relate to the nonuniformity of intra-annual distribution for precipitation. (4) The relationship between sediment load and runoff during typhoon and non-flooding season changed in 1975 and 1959, respectively, both of which were related to the heavy rainfall within the river basins.

Coastline is one of the important geographical elements to describe the boundary between land and sea. Under the dual influence of natural factors and socio-economic factors, coastline dynamic evolution of different intensities continues to occur. Based on Landsat series satellite remote sensing images, the spatial and temporal evolution of the coastline of Nan’ao Island from 1976 to 2021 was analyzed by RS and GIS technology combined with field investigation, and the driving factors were analyzed by grey correlation analysis. The results show that : (1)In the past 45 years, the coastline of Nan’ao Island has changed significantly. The coastline length has increased by 11.06 km, and the fractal dimension have generally increased.(2)During the study period, the type of coastline changed from natural coastline dominated by bedrock to artificial coastline, the comprehensive index of coastline utilization show an increasing trend, and the main structure of coastline development and utilization show a form of single to multiple.(3)The evolution of the coastline of Nan’ao Island has obvious regional differences. That of Houzhai Town is greatly affected by human factors, and its evolution is more significant. The coastlines of Yun’ao and Shen’ao Towns are mainly affected by natural factors, and their evolutions are relatively slow.(4)Typhoon(natural disasters) and population are the main driving factors of the coastline evolution of Nan’ao Island.

Two-phase leaching method can separate hydrogenetic and residual mineral phases of ferromanganese nodules, which will provide valuable information with the research of ferromanganese nodule mineralization and pale-environment. In order to study the applicability of the two-phase leaching method in the nodule mineralization research for different types of nodules compared to the bulk sample results, the ferromanganese nodules samples from six stations were selected, which were collected on the seamounts area of western Pacific Ocean and CC Zone of eastern Pacific Ocean, respectively. Geochemical and mineralogical compositions of the bulk samples were analyzed, and elements compositions of the hydrogenetic and residual mineral phases were analyzed, which were obtained using the two-phase leaching method. The results indicated that the mass ration variation of the residual mineral phases was not obvious with about 14.0%-17.6%, which had high contents of Nb, Rb, Ta, Ti, Zr. Contents and relevant rations of elements such as Co, Ni, Cu, Zn, Sr, REY in the hydrogenetic mineral phase showed similar features with those in the bulk samples. Proportion of elements contents like Ti, Nb, Sr between hydrogenetic and residual mineral phases showed well negative correlation with Mn/Fe values, which probably could be regarded as index for ferromanganese nodule mineralized environment research in the future.

The radioactive isotope radon-222(²²²Rn) is an inert element derived from the decay of uranium in the earth’s strata. Due to its stability, ease of measurement and significant difference in activity between groundwater and surface water, it has been widely used as a tracer in the study of submarine groundwater discharge (SGD) in recent years. In this study, the ²²²Rn activity of seawater was selected as the object of study, and the spatial and temporal characteristics of ²²²Rn were analyzed, and the SGD flux was estimated through a ²²²Rn mass balance model, based on two cruises of August-September, 2021 and December, 2021-January, 2022 from the northern Beibu Gulf. The results show a spatial and temporal variation of ²²²Rn distribution which was significantly affected by the terrestrial SGD process. The mean ²²²Rn activity decreased by about 40% in winter compared with that in summer. In summer, there show high ²²²Rn activity in bottom water especially from the northern part of the research area with a strong SGD process, but with low ²²²Rn activity in winter with weak SGD process. Based on the ²²²Rn mass balance model, the SGD fluxes of 4.16 cm·d^-1 in summer and 2.88 cm·d^-1 in winter were calculated from the research area, which shows significantly high SGD flux in summer dominant with nearshore SGD and low SGD flux in winter dominant with offshore SGD. Since the research area is surrounded by land and islands, the SGD processes were likely to be an important natural pathway for the terrestrial sources transporting to the nearshore waters.

The diversity and geographical distribution pattern of deep-sea polychaete animals have been a research focus of deep-sea biodiversity science. Data from the Ocean Biogeographic Information System (OBIS) were used to analyze the characters of deep-sea benthic polychaetes diversity and distribution in the western Pacific. The results show that the collection data mainly distributed in the distinctive geographic units (e.g. seamounts and trench) near coastal countries. A total of 318 species from 51 families were recorded in the study area. Polynoidae has the highest species diversity and the largest depth distribution. The number of species decreases with depth, but increases at 2 500-3 000 m and 4 000-4 500 m. The deep-sea polychaetes exhibit high levels of endemism. Many species are endemic to hydrothermal vents. For deep-sea benthic polychaetes in the western Pacific, four biogeographical areas are recognized: Sea of Japan, biogeographic area near the continent represented by Sagami Bay, region characterized by hydrothermal vents (Okinawa Trough, Manus Basin, Fiji Basin) and regions characterized by trenches or plains (Japan Trench, Kuril-Kamchatka Trench, eastern Australia and New Zealand area).

Micropropagules with rapid growth and reproduction are an important seed sources for the early outbreak of the green tide. In this study, the micropropagule seedlings of Ulva prolifera were collected as experimental materials, and two CO₂ levels (LC, 400 μatm; HC, 1 000 μatm) and three dissolved inorganic phoshphate (DIP) concentrations (LP, 0.32 μmol/L; MP, 3.62 μmol/L; HP, 36.2 μmol/L) were set to analyze the effects of CO₂, DIP and their interaction on its growth and photophysiological performance. The results of the growth indexes including relative growth rate (RGR), net photosynthetic rate (P_n) and respiration rate (R_d) showed that CO₂ significantly affected on the RGR and P_n (p<0.05). DIP significantly affected on the RGR, P_n and R_d (p<0.05). Specifically, RGR and P_n were significantly positively correlated with DIP concentration (p<0.05), while R_d was significantly negatively correlated with DIP concentration (p<0.05). However, their interaction had no significant effect on RGR, P_n and R_d (p>0.05). The results of fluorescence parameters including effective quantum yield [Y(II)], maximum relative electron transfer rate (rETR_max), saturation light intensity (E_k) and light utilization efficiency indicated (α) reveal that CO₂ significantly affected on the rETR_max and E_k (p<0.05), but had no significant effect on the Y(II) and α (p>0.05). DIP significantly affected all the fluorescence parameters, which were significantly promoted by the DIP concentration increase (p<0.05). And their interaction had significant effect on the rETR_max and Y(II) (p<0.05), but had no significant effect on the E_k and α (p>0.05). Pigments of Chl a, Chl b and carotenoid results showed that CO₂, DIP and their interaction significantly affected the pigments contents (p<0.05). Evelated-CO₂ significantly inhibited pigment synthesis (p<0.05), and the inhibitory effect was enhanced with the increasing of DIP concentration. The pigments contents were significantly positively correlated with DIP concentration (p<0.05). Our findings suggested that evelated-CO₂ and higher DIP concentration obviously promoted the growth of U.prolifera seedlings, which was favorable for the green tide outbreak.

Ship meteorological instrument is an important part of marine hydrometeorological observation technology, which is a key process to realize global synchronous ocean observation. Leading the development of consensus-based international standards will effectively promote the market standardization and product internationalization of China’s marine meteorological instrument manufacturing industry. The paper starts with the importance of ship meteorological instrument, analyzes the development process of marine meteorological instrument standards, and summarizes the current status of relevant standardization organizations. Also, it discusses how to promote the international standardization of marine meteorological instruments: (1) optimize key technical indicators; (2) cooperate with the international standardization platform of marine technology.