Combined effects of sea urchin-like structure and mixed Cu^(+)/Cu^(0)states on promoting C_(2)formation in electrocatalytic CO_(2)reduction

Surface engineering and Cu valence regulation are essential factors in improving the C_(2)selectivity during the electrochemical reduction of CO_(2).Herein,we present a sea urchin-like CuO/Cu_(2)O catalyst derived from rhombic dodecahedra Cu_(2)O through one-step oxidation/etching method where the mixed Cu^(+)/Cu^(0)states are formed via in situ reduction during electrocatalysis.The combined effects of the morphology and the mixed Cu^(+)/Cu^(0)states on C–C coupling are evaluated by the Faradaic efficiency of C_(2)and the C_(2)/C1 ratio obtained in an H-cell.R-Cu^(O)/Cu_(2)O exhibited 49.5%Faradaic efficiency of C_(2)with a C_(2)/C1 ratio of 3.1 at−1.4 V vs.reversible hydrogen electrode,which are 1.5 and 3.2 times higher than those of R-Cu_(2)O,respectively.Using a flow-cell,68.0%Faradaic efficiency of C_(2)is achieved at a current density of 500 mA·cm^(−2).The formation of the mixed Cu^(+)/Cu^(0)states was confirmed by in situ Raman spectra.Additionally,the sea urchin-like structure provides more active sites and enables faster electron transfer.As a result,the excellent C_(2)production on R-CuO/Cu_(2)O is primarily attributed to the synergistic effects of the sea urchin-like structure and the stable mixed Cu^(+)/Cu^(0)states.Therefore,this work presents an integrated strategy for developing Cu-based electrocatalysts for C_(2)production through electrochemical CO_(2)reduction.

A comparison study on structure-function relationship of polysaccharides obtained from sea buckthorn berries using different methods:antioxidant and bile acid-binding capacity

In this study,the structural characters,antioxidant activities and bile acid-binding ability of sea buckthorn polysaccharides(HRPs)obtained by the commonly used hot water(HRP-W),pressurized hot water(HRP-H),ultrasonic(HRP-U),acid(HRP-C)and alkali(HRP-A)assisted extraction methods were investigated.The results demonstrated that extraction methods had significant effects on extraction yield,monosaccharide composition,molecular weight,particle size,triple-helical structure,and surface morphology of HRPs except for the major linkage bands.Thermogravimetric analysis showed that HRP-U with filamentous reticular microstructure exhibited better thermal stability.The HRP-A with the lowest molecular weight and highest arabinose content possessed the best antioxidant activities.Moreover,the rheological analysis indicated that HRPs with higher galacturonic acid content and molecular weight showed higher viscosity and stronger crosslinking network(HRP-C,HRP-W and HRP-U),which exhibited stronger bile acid binding capacity.The present findings provide scientific evidence in the preparation technology of sea buckthorn polysaccharides with good antioxidant and bile acid binding capacity which are related to the structure affected by the extraction methods.

Spatial patterns of zooplankton abundance,biovolume,and size structure in response to environmental variables:a case study in the Yellow Sea and East China Sea

The Yellow Sea(YS)and East China Sea(ECS)are highly dynamic marginal seas of the northwestern Pacific Ocean.To gain an in-depth understanding of zooplankton community structure,zooplankton abundance,biovolume,and size structure in summer 2017 in the YS and ECS were assessed using ZooScan imaging analysis.Zooplankton abundance and biovolume ranged 2.94–1187.14 inds./m^(3)and 3.13–3438.51 mm^(3)/m^(3),respectively.Based on the biovolume data of the categorized size classes of 26 identified taxonomic groups,the zooplankton community was classified into five groups,and each group was coupled with distinctive oceanographic features.Under the influence of the Yellow Sea Cold Water Mass,the Yellow Sea offshore group featured the lowest bottom temperature(10.84±3.42℃)and the most abundant Calanoids(mainly in the 2–3 mm size class).In the Yellow Sea inshore group,Hydrozoans showed the largest biovolume and dominated in the 3–4-mm and>5-mm size classes.The East China Sea offshore group,which was affected by the Kuroshio Branch Current,featured high temperature and salinity,and the lowest bottom dissolved oxygen(2.58±0.5 mg/L).The lowest values of zooplankton abundance and biovolume in the East China Sea offshore group might be attributed to the bottom dissolved oxygen contents.The East China Sea inshore group,which was mainly influenced by the Zhejiang-Fujian Coastal Current and Changjiang Diluted Water,was characterized by high chlorophyll a and the largest biovolume of carnivorous Siphonophores(280.82±303.37 mm^(3)/m^(3)).The Changjiang River estuary offshore group showed the most abundant Cyclopoids,which might be associated with the less turbid water mass in this region.Seawater temperature was considered the most important factor in shaping the size compositions of Calanoids in different groups.

Velocity structure in the South Yellow Sea basin based on first-arrival tomography of wide-angle seismic data and its geological implications

The South Yellow Sea basin is filled with Mesozoic-Cenozoic continental sediments overlying pre-Palaeozoic and Mesozoic-Palaeozoic marine sediments.Conventional multi-channel seismic data cannot describe the velocity structure of the marine residual basin in detail,leading to the lack of a deeper understanding of the distribution and lithology owing to strong energy shielding on the top interface of marine sediments.In this study,we present seismic tomography data from ocean bottom seismographs that describe the NEE-trending velocity distributions of the basin.The results indicate that strong velocity variations occur at shallow crustal levels.Horizontal velocity bodies show good correlation with surface geological features,and multi-layer features exist in the vertical velocity framework(depth:0–10 km).The analyses of the velocity model,gravity data,magnetic data,multichannel seismic profiles,and drilling data showed that high-velocity anomalies(>6.5 km/s)of small(thickness:1–2 km)and large(thickness:>5 km)scales were caused by igneous complexes in the multi-layer structure,which were active during the Palaeogene.Possible locations of good Mesozoic and Palaeozoic marine strata are limited to the Central Uplift and the western part of the Northern Depression along the wide-angle ocean bottom seismograph array.Following the Indosinian movement,a strong compression existed in the Northern Depression during the extensional phase that caused the formation of folds in the middle of the survey line.This study is useful for reconstructing the regional tectonic evolution and delineating the distribution of the marine residual basin in the South Yellow Sea basin.

Three-Dimensional Climatological Structures of the Arabian Sea Eddies and Eddy-Induced Flux

This study explores the spatial structure and transport characteristics of eddies in the Arabian Sea(AS)using Argo profiles and satellite measurements.The majority of eddies occur in the northern AS,especially along its northeastern boundary.In contrast,the western AS had a relatively higher eddy kinetic energy compared to the eastern part.Particularly,the strongest energetic eddies were present in the Somali Current system.The composite results revealed the evident thermohaline anomalies caused by cyclonic eddies(CEs)and anticyclonic eddies(AEs)in the upper 300m layers.The anomalous temperature structure within CEs and AEs showed a dominant dipole structure in the near-surface layer and a monopole structure below,with maximum temperature anomalies of approximately−0.8℃and+1.0℃located at depths of 100–150m,respectively.The composited salinity structures for CEs and AEs exhibited monopole vertical structures and sandwich-like patterns.For AEs,large positive salinity anomalies occurred at subsurface layers of 60–180 m with a peak value of about 0.07,and weak negative values were observed above 60m and below 180 m.A similar vertical structure but with an opposite sign operates for CEs.The composited CE and AE caused an equatorward salt flux with values of−8.1×10^(4)and−2.2×10^(4)kg s^(−1),respectively.CEs caused an equatorward heat flux of−7.7×10^(11)W,and AEs induced a poleward flux of 1.5×1011 W.

Genetic diversity and population structure of the sea star Asterias amurensis in the northern coast of China

The sea star Asterias amurensis is widely viewed as a severe“marine pest”because of its broad feeding habits.Over the past few decades,A.amurensis undergoes massive and sporadic population outbreaks worldwide,causing extensive economic and ecological losses to the local aquaculture industry and marine ecosystem.Understanding the genetic diversity and population structure of A.amurensis can provide vital information for resource management.By analyzing the polymorphism of the mitochondrial cytochrome C oxidase subunit I(COI)gene and ten simple sequence repeat(SSR)microsatellites markers,the genetic diversity and population structure of A.amurensis of four populations along the northern coast of China was uncovered.A total of 36 haplotypes were identified,and a main haplotype was found in four populations.The Qingdao(QD)population displayed the highest genetic diversity among all the populations.The AMOVA and pairwise F_(st)showed that there was small but statistically significant population differentiation among the four populations,especially between QD and Weihai(WH).Moreover,the principal component analysis(PCA)and admixture analysis showed that several individuals in Yantai(YT)and Dalian(DL)had little genetic association with other individuals.Overall,this study provided useful information of the genetic diversity and population structure of A.amurensis and will contribute to the resource management of A.amurensis in China.

Three dimensional shear wave velocity structure of crust and upper mantle in South China Sea and its adjacent regions by surface waveform inversion

We assembled approximately 328 seismic records. The data set was from 4 digitally recording long-period and broadband stations of CDSN. We carried out the inversion based on the partitioned waveform inversion (PWI). It partitions the large-scale optimization problem into a number of independent small-scale problems. We adopted surface waveform inversion with an equal block (2((2() discretization in order to acquire the images of shear velocity structure at different depths (from surface to 430 km) in the crust and upper-mantle. The resolution of all these anomalies has been established with (check-board( resolution tests. These results show significant difference in velocity, lithosphere and asthenosphere structure between South China Sea and its adjacent regions.

Seasonal Variability of the Yellow Sea/East China Sea Surface Fluxes and Thermohaline Structure

We use the U.S. Navy's Master Oceanographic Observation Data Set (MOODS) forthe Yellow Sea/ East China Sea (YES) to investigate the climatological water mass features and theseasonal and non-seasonal variabilities of the thermohaline structure, and use the ComprehensiveOcean-Atmosphere Data Set (COADS) from 1945 to 1989 to investigate the linkage between the fluxes(momentum, heat, and moisture) across the air-ocean interface and the formation of the water massfeatures. After examining the major current systems and considering the local bathymetry and watermass properties, we divide YES into five regions: East China Sea (ECS) shelf, Yellow Sea (YS) Basin,Cheju bifurcation (CB) zone, Taiwan Warm Current (TWC) region, Kuroshio Current (KC) region. Thelong term mean surface heat balance corresponds to a heat loss of 30 W m^(-2) in the ESC and CBregions, a heat loss of 65 W m^(-2) in the KC and TWC regions, and a heat gain of 15 W m^(-2) in theYS region. The surface freshwater balance is defined by precipitation minus evaporation. The annualwater loss from the surface for the five subareas ranges from 1.8 to 4 cm month^(-1). The freshwater loss from the surface should be compensated for from the river run-off. The entire watercolumn of the shelf region (ECS, YS, and CB) undergoes an evident seasonal thermal cycle withmaximum values of temperature during summer and maximum mixed layer depths during winter. However,only the surface waters of the TWC and KC regions exhibit a seasonal thermal cycle.. We also foundtwo different relations between surface salinity and the Yangtze River run-off, namely, out-of-phasein the East China Sea shelf and in-phase in the Yellow Sea. This may confirm an earlier study thatthe summer fresh water discharge from the Yangtze River forms a relatively shallow, low salinityplume-like structure extending offshore on average towards the northeast.

Characteristics of the Boundary Layer Structure of Sea Fog on the Coast of Southern China

Using boundary layer data with regard to sea fog observed at the Science Experiment Base for Marine Meteorology at Bohe,Guangdong Province,the structure of the atmospheric boundary layer and the characteristics of the tops of the fog and the clouds were analyzed.In addition,the effects of advection,radiation,and turbulence during sea fog were also investigated.According to the stability definition of saturated,wet air,the gradient of the potential pseudo-equivalent temperature equal to zero was defined as the thermal turbulence interface.There is evidence to suggest that two layers of turbulence exist in sea fog.Thermal turbulence produced by long-wave radiation is prevalent above the thermal turbulence interface,whereas mechanical turbulence aroused by wind shear is predominant below the interface.The height of the thermal turbulence interface was observed between 180 m and 380 m.Three important factors are closely related to the development of the top of the sea fog：（1） the horizontal advection of the water vapor,（2） the long-wave radiation of the fog top,and（3） the movement of the vertical turbulence.Formation,development,and dissipation are the three possible phases of the evolution of the boundary-layer structure during the sea fog season.In addition,the thermal turbulence interface is the most significant turbulence interface during the formation and development periods;it is maintained after sea fog rises into the stratus layer.

Joint land-sea seismic survey and research on the deep structures of the Bohai Sea areas

This paper presents the survey and research work of two land-sea profiles in the Bohai Sea, China, carried out in 2010-2011, including the seismic sources on land and in the sea, the ocean bottom seismographs （OBS） and their recovery, the coupling of OBS and the environment noise in sea area, the data quality of OBSs, and the result of data analysis. We focused on the investigation of crustal structures revealed by the two NE／EW-trending joint land-sea profiles. In combination with the Pn-velocity distribution and gravity- magnetic inversion results in the North China Craton, we propose that the undulation of the Moho interface in the Bohai and surrounding areas is not strong, and the lithospheric thinning is mainly caused by the thinning of its mantle part. The research result indicates that obvious lateral variations of Moho depth and seismic velocity appear nearby all the large-scale faults in Bohai Sea, and there is evidence of underplating and reforming of the lower crust by mantle material in the Bohai area. However, geophysical evidence does not appear to support the ＂mantle plume＂ or ＂delamination＂ model for the North China Craton destruction. The crustal structure of the Bohai Sea revealed ＂a relatively normal crust and obviously thinned mantle lid＂, local velocity anomalies and instability phenomena in the crust. These features may represent a combined effect of North China-Yangtze collision at an early stage and the remote action of Pacific plate subduction at a late stage.

On Sea Surface Roughness Parameterization and Its Effect on Tropical Cyclone Structure and Intensity

A new parameterization scheme of sea surface momentum roughness length for all wind regimes, including high winds, under tropical cyclone （TC） conditions is constructed based on measurements from Global Positioning System （GPS） dropsonde. It reproduces the observed regime transition, namely, an increase of the drag coefficient with an increase in wind speed up to 40 m s-1 , followed by a decrease with a further increase in wind speed. The effect of this parameterization on the structure and intensity of TCs is evaluated using a newly developed numerical model, TCM4. The results show that the final intensity is increased by 10.5% （8.9%） in the maximum surface wind speed and by 8.1 hPa （5.9 hPa） in the minimum sea surface pressure drop with （without） dissipative heating. This intensity increase is found to be due mainly to the reduced frictional dissipation in the surface layer and little to do with either the surface enthalpy flux or latent heat release in the eyewall convection. The effect of the new parameterization on the storm structure is found to be insignificant and occurs only in the inner core region with the increase in tangential winds in the eyewall and the increase in temperature anomalies in the eye. This is because the difference in drag coefficient appears only in a small area under the eyewall. Implications of the results are briefly discussed.

Crustal S-wave velocity structure across the northeastern South China Sea continental margin: implications for lithology and mantle exhumation

The northeastern margin of the South China Sea (SCS), developed from continental rifting and breakup, is usually thought of as a non-volcanic margin. However, post-spreading volcanism is massive and lower crustal high-velocity anomalies are widespread, which complicate the nature of the margin here. To better understand crustal seismic velocities, lithology, and geophysical properties, we present an S-wave velocity (VS) model and a VP/VS model for the northeastern margin by using an existing P-wave velocity (VP) model as the starting model for 2-D kinematic S-wave forward ray tracing. The Mesozoic sedimentary sequence has lower VP/VS ratios than the Cenozoic sequence;in between is a main interface of P-S conversion. Two isolated high-velocity zones (HVZ) are found in the lower crust of the continental slope, showing S-wave velocities of 4.0–4.2 km/s and VP/VS ratios of 1.73–1.78. These values indicate a mafic composition, most likely of amphibolite facies. Also, a VP/VS versus VP plot indicates a magnesium-rich gabbro facies from post-spreading mantle melting at temperatures higher than normal. A third high-velocity zone (VP : 7.0–7.8 km/s;VP/VS: 1.85–1.96), 70-km wide and 4-km thick in the continent-ocean transition zone, is most likely to be a consequence of serpentinization of upwelled upper mantle. Seismic velocity structures and also gravity anomalies indicate that mantle upwelling/ serpentinization could be the most severe in the northeasternmost continent-ocean boundary of the SCS. Empirical relationships between seismic velocity and degree of serpentinization suggest that serpentinite content decreases with depth, from 43% in the lower crust to 37% into the mantle.

Seasonal characteristics and formation mechanism of the thermohaline structure of mesoscale eddy in the South China Sea

The seasonal characteristics and formation mechanism of the thermohaline structure of mesoscale eddy in the South China Sea are investigated using the latest eddy dataset and ARMOR3D data. Eddy-centric composites reveal that the horizontal distribution of temperature anomaly associated with eddy in winter is more of a dipole pattern in upper 50 m and tends to be centrosymmetric below 50 m, while in summer the distribution pattern is centrosymmetric in the entire water column. The horizontal distribution of eddy-induced salinity anomaly exhibits similar seasonal characteristics, except that the asymmetry of the salinity anomaly is weaker. The vertical distribution of temperature anomaly associated with eddy shows a monolayer structure, while the salinity anomaly demonstrates a triple-layer structure. Further analysis indicates that the vertical distribution of the anomalies is related to the vertical structure of background temperature and salinity fields, and the asymmetry of the anomalies in upper 50 m is mainly caused by the horizontal advection of background temperature and salinity.

Community structure and spatial distribution of macrobenthos in the shelf area of the Bering Sea

Field investigations of marine macrobenthos were conducted at ten sites in the Bering Sea in July 2010. Altogether 90 species of macrobenthos belonging to 59 families and 78 genera were identified. Among them, 41 polychaetes, 16 mollusks, 23 crustaceans, three echinoderms, two cnidarians, one nemertean, one priapulid, two sipunculids, and one echiuran were identified. The average density and biomass of total macrobenthos were 984 ind./m2 and 1207.1 g/ma of wet weight, respectively. The predominant species in the study area were Scoloplos armiger, Eudorella pacifica, Ophiura sarsii, Heteromastus filiformis, Ennucula tenuis, and Harpiniopsis vadiculus by abundance, while the predominant species in this area was Echinarachnius parma by biomass. Hierarchical cluster analysis （Bray-Curtis similarity measure） revealed that two impor- tant benthic assemblages in the study area were CommunityA and Community B. CommunityA was stable and Community B was unstable, as shown by the Abundance/Biomass Comparisons （ABC） approach. The macrobenthic community structure in the shelf of the Bering Sea was characterized by its high abundance and biomass, high productivity but great heterogeneity.

Modal structure and propagation of internal tides in the northeastern South China Sea

The evolution of energy, energy flux and modal structure of the internal tides (ITs) in the northeastern South China Sea is examined using the measurements at two moorings along a cross-slope section from the deep continental slope to the shallow continental shelf. The energy of both diurnal and semidiurnal ITs clearly shows a ~14-day spring-neap cycle, but their phases lag that of barotropic tides, indicating that ITs are not generated on the continental slope. Observations of internal tidal energy flux suggest that they may be generated at the Luzon Strait and propagate west-northwest to the continental slope in the northwestern SCS. Because the continental slope is critical-supercritical with respect to diurnal ITs, about 4.6 kJ/m^2 of the incident energy and 8.7 kW/m of energy flux of diurnal ITs are reduced from the continental slope to the continental shelf. In contrast, the semidiurnal internal tides enter the shelf because of the sub-critical topography with respect to semidiurnal ITs. From the continental slope to the shelf, the vertical structure of diurnal ITs shows significant variation, with dominant Mode 1 on the deep slope and dominant higher modes on the shelf. On the contrary, the vertical structure of the semidiurnal ITs is stable, with dominant Mode 1.

A comparison of summer precipitation structures over the South China Sea and the East China Sea based on tropical rainfall measurement mission

The three-dimensional structures of summer precipitation over the South China Sea （SCS） and the East China Sea （ECS） are investigated based on tropical rainfall measurement mission （TRMM）. The primary results are as follows. First, both the convective and stratiform precipitation rates in the SCS are much higher than those of the ECS. The contribution of the convective cloud precipitation to the surface precipitation is primarily over the SCS and the ECS with a proportion of about 70%, but the contribution of convective cloud precipitation is slightly larger in the SCS than the ECS. The contribution of stratus precipitation is slightly larger in the ECS than that in the SCS. Second, the content of cloud particles and precipitation particles in the ECS in June was greater than that in the SCS, while in July and August, the content of cloud and precipitation particles in the ECS was less than that in the SCS. Third, the latent heat profile of the ECS is quite different from that of the SCS. In June, the peak values of evaporation and condensation latent heating rates in the ECS are greater than those in the SCS. In July and August, however, the peak values of evaporation and condensation latent heating rates in the ECS are about 0.05°/h less than those in the SCS.

The winter western boundary current of the South China Sea:physical structure and volume transport in December 1998

The unique survey in December 1998 mapped the entire western boundary area of the South China Sea（SCS）,which reveals the three-dimensional structure and huge volume transport of the swift and narrow winter western boundary current of the SCS（SCSwwbc） in full scale. The current is found to flow all the way from the shelf edge off Hong Kong to the Sunda Shelf with a width around 100 km and a vertical scale of about 400 m. It appears to be the strongest off the Indo-China Peninsula, where its volume transport reached over 20×10~6 m^3/s. The current is weaker upstream in the northern SCS to the west of Hong Kong. A Kuroshio loop or detached eddy intruded through the Luzon Strait is observed farther east where the SCSwwbc no more exists. The results suggest that during the survey the SCSwwbc was fed primarily by the interior recirculation of the SCS rather than by the＂branching＂ of the Kuroshio from the Luzon Strait as indicated by surface drifters, which is likely a near-surface phenomenon and only contributes a minor part to the total transport of the SCSwwbc. Several topics related to the SCSwwbc are also discussed.

A numerical study of the wintertime double-warm-tongue structure in the Huanghai(Yellow) Sea

Satellite remote sensing observations show that during winter, sea surface temperature （SST） presents the structure of double warm tongues in the Huanghai Sea trough： the western and the eastern warm tongues. Numerical experiments based on POM are carried out to study the forming mechanism of this thermal structure and its relation to the Huanghai Sea Warm Current （HSWC）. The control experiment reproduces this phenomenon quite well, and comparing experiments investigate the effect of wind and tide. It is found that the western warm tongue is mainly caused by the HSWC, which can be strengthened by wintertime southward wind. The eastern warm tongue develops under the influence of an anti-clockwise circulation which is induced by the temperature front of the Huanghai Sea Cold Water Mass （HSCWM） in summer and autumn. In the eastern portion of this circulation, the northward current carries warm water to the north, forming the eastern warm tongue, which remains till winter.

TRMM-retrieved Cloud Structure and Evolution of MCSs over the Northern South China Sea and Impacts of CAPE and Vertical Wind Shear

Cloud structure and evolution of Mesoscale Convective Systems （MCSs） retrieved from the Tropical Rainfall Measuring Mission Microwave Imager （TRMM TMI） and Precipitation Radar （PR） were investigated and compared with some pioneer studies based on soundings and models over the northern South China Sea （SCS）. The impacts of Convective Available Potential Energy （CAPE） and environmental vertical wind shear on MCSs were also explored. The main features of MCSs over the SCS were captured well by both TRMM PR and TMI. However, the PR-retrieved surface rainfall in May was less than that in June, and the reverse for TMI. TRMM-retrieved rainfall amounts were generally consistent with those estimated from sounding and models. However, rainfall amounts from sounding-based and PR-based estimates were relatively higher than those retrieved from TRMM-TMI data. The Weather Research and Forecasting （WRF） modeling simulation underestimated the maximum rain rate by 22% compared to that derived from TRMM-PR, and underestimated mean rainfall by 10.4% compared to the TRMM-TMI estimate, and by 12.5% compared to the sounding-based estimate. The warm microphysical processes modeled from both the WRF and the Goddard Cumulus Ensemble （GCE） models were quite close to those based on TMI, but the ice water contents in the models were relatively less compared to that derived from TMI. The CAPE and wind shear induced by the monsoon circulation were found to play critical roles in maintaining and developing the intense convective clouds over SCS. The latent heating rate increased more than twofold during the monsoon period and provided favorable conditions for the upward transportation of energy from the ocean, giving rise to the possibility of inducing large-scale interactions.

Community structure and biodiversity of free-living marine nematodes in the northern South China Sea

A quantitative study on the community structure and biodiversity of free-living marine nematodes and their relationship with environmental factors in the northern South China Sea were carried out based on the samples collected at five stations in the deep sea （from 313 to 1 600 m） and one station in shallowwaters （87 m） during the cruise in September, 2010. Results showed that the abundance of marine nematodes ranged from 224 to 1 996 ind./（10 cm2）. A total of 69 free-living marine nematode genera, belonging to 26 families and three orders, were identified. The most dominant genera were Sabatieria, Linhystera, Aegialoalaimus and Daptonema according to SIMPER analysis. Results of CLUSTER analysis revealed four types of marine nematode community （or station groups） in the sampling area. In terms of trophic structure, non-selective deposit feeders （1B） and selective deposit feeders （1A） were the dominant trophic types with highest genera numbers and abundances, which implied that organic detritus was the main food source of marine nematodes in the northern South China Sea. The percentage of male nematode was low, ranging from 2.22% to 17.81%, while those of juvenile individuals ranged from 36.99% to 82.09%. For genera level diversity of marine nematodes, Shannon-Wiener diversity indices （H＇） ranged from 3.76 to 4.57 and had highly significant negative correlation with water depth. In general, diversity indices H＇ at the five stations in deep sea （over 200 m） were lower than that at the station in shallow waters （87 m）. BIOENV analysis showed that the most important environmental factor controlling marine nematode communities was water denth.