Feature article

Please wait a minute...
For Selected: Toggle Thumbnails
Journal of Marine Sciences    2024, 42 (1): 117-118.  
Abstract16)   HTML1)    PDF (2850KB)(8)      
Method for determining the foot point of continental slope in complex geological background: Take the southern continental margin of Mozambique as an example
ZHUANG Baojiang, TANG Yong, LÜ Xiaohui, YANG Chunguo, WU Zhaocai, LI He
Journal of Marine Sciences    2024, 42 (1): 13-22.   DOI: 10.3969-j.issn.1001-909X.2024.01.002
Abstract34)   HTML6)    PDF (6192KB)(8)      

A new method for determining the foot point of the continental slope (FOS) was proposed for the delineation of the continental shelf in a complex geological context. This method calculated the location of the foot of slope based on the mean gradient of water depth and optimized it by combining the contrary evidence and the principles of convexity, segmentation and continuity. Using the southern continental margin of Mozambique as the study area, the method was applied to extract the most critical basis—FOS for continental shelf delineation using high-precision multibeam topographic data measured in 2021, and the result was confirmed by comparison with those extracted by the Geocap software which is used by the United Nations Commission on the Limits of the Continental shelf, proving the effectiveness and accuracy of this method.

Investigation of carotenoid biosynthesis genes in marine Erythrobacteraceae strains
YUE Xiaolan, XU Lin, FU Geyi, XU Xuewei
Journal of Marine Sciences    2024, 42 (1): 91-105.   DOI: 10.3969-j.issn.1001-909X.2024.01.009
Abstract19)   HTML3)    PDF (23947KB)(4)      

Erythrobacteraceae is widely distributed in marine environments and can synthesize various pigments such as carotenoids. Carotenoids have photoprotective and antioxidant abilities, and they can play a crucial role in the adaptation of Erythrobacteraceae to marine ecosystems. In this study, we obtained the genomes of 107 marine Erythrobacteriaceae strains, analyzed the distribution characteristics of carotenoid biosynthesis genes including crtEBIGYZW in their genomes, constructed phylogenetic trees based on the amino acid sequences of the carotenoid biosynthesis genes, and elucidated the presence and distribution of carotenoid biosynthesis genes in Erythrobacteriaceae from deep-sea and shallow-sea sources. The results suggested that all of marine Erythrobacteriaceae strains contained the crtEIGZ genes, 98.1% of strains contained the crtBY genes, and 43.9% of them contained the crtW gene, which differed among strains but no any specificities found among the deep-sea or shallow-sea sources. Additionally, in the comparison of the phylogenetic topology, it was found that the crtBYZW genes were vertically transferred from their ancestor, while the crtEIG genes were mainly horizontal gene transferred. Our study aids in the understanding of the carotenoid biosynthesis gene evolution in the family Erythrobacteriaceae and also serves as a scientific basis for the study of carotenoid synthesis pathways and genes in other marine bacteria, enables a thorough understanding of marine carotenoid-synthesizing strains.

The seasonal blooming characteristics of phytoplankton and POC export flux in the waters around South Georgia Island: Based on BGC-Argo and satellite remote sensing observations
ZHAO Yueran, FAN Gaojing, WU Jiaqi, SUN Weiping, PAN Jianming, HAN Zhengbing
Journal of Marine Sciences    2023, 41 (4): 1-11.   DOI: 10.3969/j.issn.1001-909X.2023.04.001
Abstract132)   HTML31)    PDF (2882KB)(97)      

The waters surrounding South Georgia Island are one of the highest primary productivity regions in the Southern Ocean with enormous carbon sequestration potential. However, the strength of the biological pump efficiency in this area is still uncertain due to the lack of continuous upper ocean observation data.In this study, the hydrological and biogeochemical parameters obtained from the Biogeochemical Argo (BGC-Argo) floats deployed in the South Georgia Island vicinity during the period of 2017-2020 were utilized to investigate the impacts of physical processes on biogeochemical processes and to estimate the carbon export flux in the Antarctic summer. Results indicated that both upstream (northeast of the Antarctic Peninsula) and downstream (Georgia Basin) regions of South Georgia Island exhibited strong seasonal characteristics in Chl-a, with the latter area having a 4-month sustained period of phytoplankton bloom, suggesting a stable and continuous supply of iron. Using the temporal variability of the seasonal particulate organic carbon (POC) export, the summer POC export fluxes of the upstream and downstream regions were estimated to be 7.12±3.90 mmol·m-2·d-1 and 45.29±5.40 mmol·m-2·d-1, respectively, indicating that the difference might be due to enhanced downward export of organic carbon after the deepening of the mixed layer. The study found that the region maintained a high biological pump efficiency, contrary to the previous conclusion that the Georgia Basin had “high productivity low export efficiency”, which might have been caused by the limited “real-time” representation of the entire seasonal characteristics during ship-based surveys. BGC-Argo provides high spatiotemporal resolution of multi-parameter observation data, and this study demonstrates that it can more accurately quantify and evaluate marine biogeochemical processes and carbon sequestration potential.

Study on frequency shift of typhoon-excited near-inertial waves in northwestern South China Sea
FU Dianfu, XIE Botao, HUANG Bigui, JIN Weifang, MOU Yong, LIN Feilong
Journal of Marine Sciences    2023, 41 (4): 12-20.   DOI: 10.3969/j.issn.1001-909X.2023.04.002
Abstract95)   HTML13)    PDF (2573KB)(49)      

Near-inertial waves (NIWs) play an important role in the response of ocean to typhoon. Their frequency varies with the depth and is the main factor in determining the propagation rate of near-inertial energy to the ocean interior. Based on the observation data from mooring, the factors affecting the blue-shift frequency of NIWs excited by typhoon were investigated in northwestern South China Sea. By analyzing the vorticity effect and Doppler effect caused by background currents, this study suggests that the Doppler effect of background currents was the main factor in the blue-shift frequency of NIWs. As depth increased, inertial wave frequencies increased. Quantitative calculations further demonstrated that within the upper 200 meters, the Doppler effect of the background currents was negative, approaching zero in depth around 200 meters. However, in the depth range of 230 to 400 meters, the Doppler effect became positive. This depth range exhibited the maximum strength of the background currents, with their direction aligned with the propagation direction of inertial waves. Consequently, the positive Doppler shift induced by the background currents was most pronounced. The results of this study are important for improving the understanding of the ocean response to typhoons, especially the propagation of near-inertial waves in areas with complex background current structure (e.g., the western boundary current region).

Numerical investigation of the super typhoon Mangkhut based on the coupled air-sea model
LÜ Zhao, WU Zhiyuan, JIANG Changbo, ZHANG Haojian, GAO Kai, YAN Ren
Journal of Marine Sciences    2023, 41 (4): 21-31.   DOI: 10.3969/j.issn.1001-909X.2023.04.003
Abstract111)   HTML22)    PDF (8056KB)(72)      

Based on the mesoscale atmospheric model WRF and the regional ocean model ROMS, a two-way coupled WRF-ROMS air-sea model was constructed to simulate the super typhoon Mangkhut in 2018. The results showed that the simulation results of the coupled air-sea model were better than those of the only atmospheric or ocean model, and the error of the typhoon track obtained from the coupled model was within 60 km, which was in good agreement with the best track. Compared with the observation results, the simulation results of wind speed and sea level pressure in the coupled model were better than others model. Based on the simulation results of the coupled air-sea model, the spatial and temporal distribution of the wind field, pressure field, sea surface flow field, and storm surge under the super typhoon Mangkhut were further analyzed. The results showed that: (1) In terms of spatial distribution, after the typhoon entered the South China Sea, the radius of the seven-level wind circle was larger behind the right side of the typhoon; the cyclonic flow field showed a significant Ekman effect with the typhoon wind field, and the flow direction was 45° from the wind direction. The wind field, pressure field, wind-generated flow field and water gain distribution all had obvious asymmetry, and the typhoon intensity, flow velocity and water gain were greater on the right side of the typhoon path than on the left side. (2) In terms of time distribution, the distribution of the wind field and the pressure field were similar and synchronized with the typhoon center, while the wind-driven flow field and storm surge were three hours behind the typhoon track.

Quantification of nitracline depth in seawater
MENG Yu, CHEN Shuangling
Journal of Marine Sciences    2023, 41 (3): 1-13.   DOI: 10.3969/j.issn.1001-909X.2023.03.001
Abstract163)   HTML24)    PDF (2949KB)(126)      

Nitrate is the main nitrogen form available for phytoplankton life activities in the ocean, and its nitracline depth (ZN) directly affects the vertical transport of nitrate and the ocean primary productivity, and then further influences the carbon cycle. With the advancement of ocean observation technologies, the profile data of nitrate have been collected in diversified ways, such as ship-based CTD observations and BGC-Argo automatic observations. The vertical sampling resolution of these techniques varies significantly (the vertical sampling resolution of CTD is lower than that of BGC-Argo). In view of different sampling data, it is urgent to conduct systematic and quantitative comparative analysis and study on the computing methods of ZN. In this study, three different methods: difference method, gradient method and threshold method, are adopted to compute the corresponding ZN by using the historical ship-based CTD data and BGC-Argo buoy data in the Northwest Pacific Ocean. The results show that in the case of single nitrate profile, based on BGC-Argo data, the difference between observed ZN and the ZN calculated by difference method is only 0.2 m, followed by threshold method is 20.0 m and gradient method is 202.8 m at most. Based on CTD data, the difference between observed ZN and ZN calculated by difference method is 2.0 m, the threshold method is 49.0 m, and the gradient method is 155.0 m. Compared with the gradient method and threshold method, the difference between the ZN calculated by the difference method and the observed ZN is the smallest. According to the results of statistical error analysis, it is found that the ZN calculated by the three methods based on BGC-Argo data show a good correlation with the observed ZN. Among them, the error of difference method is the smallest (R2=0.77, RMSE=28.48 m). The R2 and RMSE of threshold method are 0.64 and 34.85 m, and the R2 and RMSE of gradient method are 0.52 and 53.80 m. For CTD data, due to its low vertical sampling resolution, the ZN calculated by the three methods is quite different from the observed ZN. However, compared with the gradient method and threshold method, the error of the difference method is still the smallest (R2=0.81, RMSE =16.13 m). The R2 and RMSE of threshold method are 0.47 and 27.65 m, and the R2 and RMSE of gradient method are 0.42 and 36.41 m. The applicability of each method is preliminarily explored through comparing and analyzing the characteristics and differences of them so as to provide some scientific reference for the in-depth research on the vertical distribution characteristics and upward transport process of nitrate.

Variations of pCO 2 and sea-air CO 2 flux in Qingdao coastal seawater in spring based on buoy observations
ZHOU Xuehang, ZHANG Honghai, MA Xin, CHEN Zhaohui
Journal of Marine Sciences    2023, 41 (3): 14-21.   DOI: 10.3969/j.issn.1001-909X.2023.03.002
Abstract112)   HTML20)    PDF (2605KB)(106)      

Based on the high frequency data of sea-air interface buoys, the variation pattern and driving factors of sea-air partial pressure of carbon dioxide (pCO2) were analyzed and the sea-air CO2 flux in the coastal waters of Qingdao in spring was estimated. During the observation period, the sea area changed from a carbon sink of atmospheric CO2 to a carbon source, which was mainly caused by the continuous increase of sea surface pCO2. By analyzing the controlling factors of pCO2, it was found that temperature was the main driving factor of pCO2 growth, and biological processes played a certain inhibiting role. The sea surface pCO2 showed a diurnal variation. The effects of temperature and biological factors on the diurnal variation of pCO2 were related to solar radiation, but they had opposite effects. In addition, the analysis showed that different sampling frequencies of buoys affected the estimation of sea-air CO2 flux and shortening the sampling interval could effectively reduce the deviation of CO2 flux estimation and improve the accuracy of estimation.

Spatiotemporal variation of surface eddy kinetic energy in the South Australian Basin
LIU Jia, ZHENG Shaojun, YAN Li, CHEN Hangbiao, LIU Tingzhen
Journal of Marine Sciences    2023, 41 (3): 22-33.   DOI: 10.3969/j.issn.1001-909X.2023.03.003
Abstract112)   HTML18)    PDF (5728KB)(86)      

The spatiotemporal variation of surface eddy kinetic energy (EKE) in the South Australian Basin was studied using sea level anomaly during 1993-2019. The results show that in spatial scale there are two regions of high EKE: one to the west, and one to the east. On the seasonal scale, surface EKE is the strongest in austral winter with a maximum (57±9 cm2/s2) in July and the weakest in autumn with a minimum (40±5 cm2/s2) in March. On the interannual scale, surface EKE is related to El Niño-Southern Oscillation (ENSO) and Southern Annular Mode (SAM). Partial correlation analysis indicates that surface EKE shows negative correlations with ENSO, lagging the Niño3.4 index by 9 months, and EKE is significantly weakened (strengthened) in the decaying year of El Niño (La Niña). Meanwhile, surface EKE shows positive correlations with SAM, lagging SAM index by 14 months, and EKE is significantly strengthened (weakened) in the next year of the positive (negative) SAM phases.

Interactions between vegetation and sediment carbon pools within coastal blue carbon ecosystems: A review and perspective
CHEN Yining, CHEN Luzhen
Journal of Marine Sciences    2023, 41 (1): 3-13.   DOI: 10.3969-j.issn.1001-909X.2023.01.001
Abstract398)   HTML275)    PDF (1348KB)(286)      

Mangroves, coastal salt marshes and seagrass beds, as the typical coastal blue carbon ecosystems, have been widely recognized for their remarkable capacity in carbon storage. Vegetation carbon pool and sediment (or soil) carbon pool were considered to be the major carbon pools within the coastal blue ecosystems and their variations determined the overall carbon sequestration of the ecosystems. From a perspective of carbon pool interactions, this study summarized the previous research work based on literature review, including the interactions within various vegetation carbon pools and within various sediment carbon pools, as well as the interactions between vegetation and sediment carbon pools. Interspecific competition, allochthonous carbon input and biogeomorphology were found to be the key to understand the carbon pool interactions. Finally, a perspective on the current state-of-the-art of blue carbon pool study is offered, with challenges and suggestions for future directions.

Carbon cycling in costal ocean and CO 2 negative emissions
YU Lei, LI Sanzhong, SUO Yanhui, WANG Xiujuan
Journal of Marine Sciences    2023, 41 (1): 14-25.   DOI: 10.3969-j.issn.1001-909X.2023.01.002
Abstract241)   HTML24)    PDF (2925KB)(239)      

Costal ocean receives a bunch of carbon materials and nutrients from terrestrial sources, relates a lot of carbon-involving interactions. Meanwhile, it is normal that sedimentary reservoir-cap systems with good trap conditions beneath coastal ocean, these entrapments have potentials to storage CO2. This review focuses on the coastal ocean as the research object, and introduces the carbon cycle processes in coastal ocean, their factors which could influence CO2 fluxes in the carbon cycle processes, and the potential carbon storage mechanisms of the coastal marine sedimentary basins. From the perspective of “carbon peaking and carbon neutrality”, the significance of coastal oceans for “Ocean Negative Carbon Emission (ONCE)”, its potential promotion paths, carbon storage potentials in sedimentary basins and the problems faced by coastal oceans are discussed. Overall, the costal ocean is one of the important blue carbon sink areas. In the coastal marine seawater system, improving the reaction efficiency of microbial carbon pump and carbonate carbon pump have positive significance for CO2 negative emissions; The suitable reservoir-cap systems for CO2 storage beneath coastal ocean can not only provide extra spaces, but also guarantee the safety for CO2 storage. In the future, the main research directions should be to inhibit the conversion process of carbon materials to CO2 in coastal oceans and ensure the safety of CO2 storage in sedimentary reservoirs, these could provide theoretical basis and technical guarantee for CO2 negative emissions.

Explorations of marine gas hydrate deposits and the signatures of hydrocarbon venting using in situ techniques
LIU Liping, CHU Fengyou, GUO Lei, LI Xiaohu
Journal of Marine Sciences    2023, 41 (1): 26-44.   DOI: 10.3969-j.issn.1001-909X.2023.01.003
Abstract244)   HTML20)    PDF (4566KB)(666)      

Marine gas hydrate deposits are significant temporal reservoirs for hydrocarbons migrating from deep sources. This is crucial to our understanding of ocean carbon cycling. The cold seep, a geological process regarding gas leakage from deep or shallow sources, is usually linked with gas hydrate decomposition. In this thesis, we reviewed the latest applications of in situ monitoring and detecting methods regarding the leakage plumes, migration pathways, and seafloor geomorphologies associated with gas hydrate and cold seep systems, primarily including vessel-and land-based gas plume measurements, surface ocean-lower atmosphere hydrocarbon emission detections, seafloor visualization techniques, and in situ observation networks. The integrated applications of these in situ observation methods provide a nuanced view of the temporal and spatial variability of hydrate and cold seep systems, facilitate understanding of the fate of hydrocarbons, and expand our knowledge of cold-seep biota in a watery desert.

Distribution, movement and generation mechanism of the mesoscale eddy around the Kuroshio in the East China Sea
LI Zhichao, GUO Junru, SONG Jun, BAI Zhipeng, FU Yanzhao, CAI Yu, WANG Xifeng
Journal of Marine Sciences    2022, 40 (4): 1-10.   DOI: 10.3969j.issn.1001-909X.2022.04.001
Abstract448)      PDF (3317KB)(273)      
In order to explore the distribution, formation mechanism and motion law of eddy around Kuroshio in East China Sea, firstly, the eddy distribution around the Kuroshio in the East China Sea during the past 27 years was analyzed by using the mesoscale eddy data set of the AVISO(Archiving, Validation and Interpretation of Satellite Oceanographic Data). The results show that there are 650 eddies generated in the meander of the Kuroshio, and 271 eddies in the middle part of the Kuroshio. The diameters of the most these eddies were between 100 to 150 km, and the amplitudes were between 2 to 6 cm. Secondly, the motion path and eddy motion process of the Kuroshio in the East China Sea are also analyzed. The results show these the cyclonic eddies are easy to be generated in the inner side of the Kuroshio cyclonic bend, with a long path. For example, at the cyclone bend of the Kuroshio axis in the northeast of Taiwan, the average length of the path was 87.6 km. Otherwise, when these anticyclonic eddies are generated, these eddies usually are wandered. In the middle part of the Kuroshio, the eddy showed the polar symmetric distribution characteristics of these cyclonic eddies in the west side of the Kuroshio main axis and these anticyclonic eddies in the east side of the Kuroshio main axis. Both types of eddies moved northeastward along the Kuroshio main axis. Finally, combined with reanalysis data sets of ocean current and sea surface height, the eddy motion law and generation mechanism were discussed. It is concluded that these eddies generation at the curve of the Kuroshio are related to the separation of the boundary layer of the Kuroshio fluid. The Kuroshio countercurrent from the south of Yanmei Island to the west of Okinawa Island played a key role in the polar symmetric distribution of these eddies in the middle part of the Kuroshio. These eddies usually experience three stages of growth, maturation and decay in the process of movement.
Characteristics and tectonic implications of the Mesozoic residual strata in the East China Sea Shelf Basin
WANG Lei, LI Chunfeng, LI Kedi, YAO Zewei, TAO Tiansheng
Journal of Marine Sciences    2022, 40 (4): 11-24.   DOI: 10.3969j.issn.1001-909X.2022.04.002
Abstract249)      PDF (6951KB)(63)      
The East China Sea Shelf Basin is a Mesozoic and Cenozoic superimposed basin with high oil and gas potential. At present, the discovery of oil and gas in the basin comes from the Cenozoic reservoirs, and various aspects of the Mesozoic residual strata are less known. Furthermore, previous qualitative or semi-quantitative studies are usually spatially limited within specific structural units in the western part of the basin and mainly involves Cretaceous and Jurassic. This study collects and sorts out the latest reflection seismic data and well data penetrated into the Mesozoic in the entire study area. Based on seismic sequences of the Cretaceous, Jurassic and Pre-Jurassic, our results show that the Mesozoic residual strata in the East China Sea Shelf Basin suffered from severe denudation in the later period. The Mesozoic residual strata generally thicken to the east and south, and the range of residual strata expanded eastward over time. Comparing the distribution characteristics of the residual strata between different periods, it is further supported that the East China Sea Shelf Basin was a passive continental margin depression basin in the Triassic, and an active continental margin fore-arc basin in the Early-Middle Jurassic, and a continental margin back-arc extensional basin in the late Jurassic to late Cretaceous. Correspondingly, the subduction of the paleo-Pacific plate began in the Late Triassic-Early-Middle Jurassic, and the retreat of the plate began in the Late Jurassic. The east boundary of the Mesozoic proto of the East China Sea Shelf Basin was located on the east side of the Diaoyu Island uplift.
Alkaline phosphatase activity of size-fractionated phytoplankton in the Changjiang Estuary in summer
WANG Yiheng, HAO Qiang, CHEN Jianfang, ZHU Yuanli, JIN Haiyan, ZHOU Feng, ZHANG Wei
Journal of Marine Sciences    2022, 40 (4): 25-37.   DOI: 10.3969j.issn.1001-909X.2022.04.003
Abstract350)      PDF (3517KB)(116)      
Alkaline phosphatase activity (APA) is an important indicator of phytoplankton phosphorus limitation status in the marine science study. In the “nitrogen-excess” areas such as the Changjiang Estuary (CJE), phosphorus is a major factor controlling the primary productivity in the sea. However, the extent of phosphorus limitation is often difficult to define and little is known about the effect of phosphorus limitation on phytoplankton at different sizes. In this study, the spatial distribution of phytoplankton (Net: ≥20 μm; Nano: 2~20 μm; Pico: 0.8~2 μm) APA, bacterioplankton APA (0.2~0.8 μm) and dissolved APA (<0.2 μm) in the surface layer of the CJE in the summer of 2020 were given, and the correlation between APA and environmental factors were analyzed. The results showed that size-fractionated phytoplankton APA was negatively correlated with dissolved inorganic phosphate (DIP), indicating that DIP concentration was the main factor affecting the distribution of size-fractionated phytoplankton APA. In the spatial distribution, phytoplankton APA was lower in the light-limitation zone near the mouth, and showed an increasing trend from the mouth to the east, contrary to the distribution of DIP. Net and Nano phytoplankton APA (mean values of (40.28±32.35) nmol/(L·h) and (52.38±34.78) nmol/(L·h), respectively) were significantly higher than Pico phytoplankton APA (mean values of (28.43±20.23) nmol/(L·h)) in the CJE, implying that large size phytoplankton were more susceptible to DIP decline. In this study, the DIP concentration for inducing a rapid increase in phytoplankton APA was 0.159 μmol/L, which was close to the empirical threshold for nearshore phosphorus limitation. This study revealed the characteristics of phytoplankton response to phosphorus distribution in the CJE at different grain levels in summer, and also contributed to the understanding of the environmental regulatory mechanisms of primary production processes in the CJE.
Complex parameterization for land-ocean interface: A perspective
LI Yan, CHEN Yining, WU Xiangbai
Journal of Marine Sciences    2022, 40 (3): 3-8.   DOI: 10.3969-j.issn.1001-909X.2022.03.001
Abstract304)      PDF (1384KB)(192)      
 Land-ocean interface has been a challenge in determining the boundary conditions for earth system modelling. Due to the uncertainty of material fluxes, the localization effect on counter gradient convergence, and the existence of self-adapted structures, land-ocean interface is unable to be monitored ergodically under the framework of classic linear theory. There is a great difficulty in quantifying real parameters for this interface, which is the key connection between linear and nonlinear systems under harmonic conditions, to better improve the simulation and prediction capability of earth system modelling. In a previous work, based on a two-dimensional multi-constituent tidal model and its adjoint model, together with assimilation using satellite altimeter data and tidal gauge array data, the spatial and temporal variation in bottom friction coefficient was estimated in an improved way. Inspired by the abovementioned study, this contribution proposed a suggestion of complex parameterization for land-ocean interface, in combination with remote sensing observation and numerical modelling.

Qiongzhou Strait as a self-adapted low-passing filter?
LI Yan
Journal of Marine Sciences    2022, 40 (3): 9-16.   DOI: 10.3969-j.issn.1001-909X.2022.03.002
Abstract276)      PDF (1618KB)(416)      
Since a diagram depicting "The Great Ocean Conveyor" was first appeared as a logo by Wally Broecker in 1987, how the warmed upper ocean circulation ran through the Indonesian Seas with their complex coastline geometry and narrow passages, known as the Indonesian through-flow, becomes one of the difficult settings in boundary conditions of climate change model. With strong nonlinear effect, a shallow narrow passage forms vertical mixed hotspots on the one hand, and on other hand, it becomes a self-adapted low-pass filter if the tidal resonance units are introduced. Qiongzhou Strait, a sufficient sediment supply and shallow narrow passage for the northern shelf of the South China Sea, is reported with strong tidal current and westward through-flow. And its tidal channel and tidal deltas are maintained by the tidal resonance units introduced themself. Strong disturbances such as typhoon and cold wave can cause storm jet flow through the strait, triggering different high nutrition, algal bloom and hypoxia events over the adjacent Beibu Gulf. Qiongzhou Strait seems to be a noteworthy case of studying how the self-adapted low-pass filter introduced and whether human activities can affect the through-flow on the shallow narrow passages.

Driving force of marine sedimentary source to sink: A case study from Beibu Gulf
Journal of Marine Sciences    2022, 40 (3): 17-32.   DOI: 10.3969-j.issn.1001-909X.2022.03.003
Abstract387)      PDF (3784KB)(292)      
Progress of marine sand resource exploration around Hainan Island and suggestions for selection of exploration areas
TONG Changliang, SONG Jiawei, DENG Kaizhang, HAN Xiaohui, WANG Aijun, WANG Yaping
Journal of Marine Sciences    2022, 40 (3): 33-48.   DOI: 10.3969-j.issn.1001-909X.2022.03.004
Abstract300)      PDF (4123KB)(260)      
Marine sands are important submarine mineral resources. The marine sand resources of Hainan Island are widely distributed in coastal zones and continental shelf areas, with large scale, good quality and rich in heavy minerals. The basic distribution characteristics of marine sand resources around Hainan Island are described, and the progress and main achievements of marine sand exploration around Hainan Island are reviewed with emphasis on heavy mineral sand and aggregate sand. Through the exploration, 15 abnormal areas of heavy mineral placer have been delineated in the sea area around Hainan Island, and one large zirconiumtitanium placer deposit has been proved. However, due to the low level of investigation and research, the resource potential of heavy mineral placer is not clear. The scale of sediment survey around Hainan Island has basically reached 1∶250 000, which provides a solid foundation for the exploration of aggregate sand resources. In recent years, billions of cubic meters of aggregate sand resources have been discovered in the east entrance of Qiongzhou Strait and tidal sand ridge area of the western Hainan, and the resource potential is predicted to reach tens of billions of cubic meters. According to the comprehensive analysis, 8 potential exploration areas of marine sand resources can be delineated around Hainan Island. Except the east mouth of Qiongzhou Strait and the tidal sand ridge area of the western Hainan, the northeast continental shelf of Hainan, the southwest continental shelf of Hainan and Beibu Gulf area are all favorable enrichment areas of marine sand resources, and may contain heavy mineral resources potential. According to the specific sedimentary environment, the exploration objectives and tasks of each prospective area are discussed respectively. Combined with the current work progress and existing problems, the suggestions for the future marine sand exploration are put forward.

Principles and methods for determining the foot of the continental slope
FANG Yinxia, LI Jiabiao, YIN Jie, LIU Weiyong, TANG Yong,
Journal of Marine Sciences    2022, 40 (2): 1-9.   DOI: 10.3969-j.issn.1001-909X.2022.02.001
Abstract511)      PDF (2690KB)(172)      

The foot of the continental slope is an important topographical feature of the continental margin. Its the basis for coastal states to extend its continental shelf rights and to delimit the outer limit of the continental shelf beyond 200 nautical miles. Its also an important technical parameter that the Commission on the Limits of the Continental Shelf pays special attention to when considering the submissions of coastal states. The formulation of the continental shelf regime in Article 76 of the United Nations Convention on the Law of the Sea originates from the typical passive continental margin. However, due to the diversity and complexity of the global continental margin, especially the transformation and influence of late tectonic activities and sedimentation on the continental margin, the seabed topography is extremely complex and changeable, which makes it very difficult to identify the foot of the continental slope. In addition, in order to obtain the largest extent of the outer continental shelf, each coastal state has interpreted the relevant provisions of the foot of the continental slope in their own favor, making the foot of the continental slope a hot and controversial issue in the delimitation of the outer continental shelf. Based on the provisions of the United Nations Convention on the Law of the Sea and the "Scientific and Technical Guidelines of the Commission on the Limits of the Continental Shelf" on the foot of the continental slope, combined with the geological characteristics of different types of continental margins and the delimitation practice of various coastal states, the determination of the base of the continental slope, the selection of the point of greatest change and the application of the evidence to the contrary are discussed.