Sri Lanka, an island nation, holds strategic importance as a key node in the Indian Ocean shipping routes. This paper delves into the unique geological structure of Sri Lanka, characterized by steep terrain and frequent geological hazards, against a backdrop of limited preventive capabilities. Commencing with an analysis of these geological structure, we highlight the pressing livelihood and welfare challenges caused by recurrent geological hazards. Subsequently, we underscore the urgency and feasibility of establishing a comprehensive geological monitoring platform in coastal cities to address these challenges. We then elaborate on a three-phase deployment strategy for this early geological hazard monitoring platform, demonstrating its practical application. Furthermore, we identify two critical scientific issues requiring immediate attention: (1) the tectonic evolution mechanism of Sri Lanka, and (2) the stability of shallow geological structures in coastal cities. To this end, we emphasize the necessity of utilizing the latest seismic data to focus on studies of geological and velocity structures in Sri Lanka's coastal areas. Establishing standards for geological stability assessment and analyzing the temporal and spatial variation characteristics of geological hazards will provide scientific evidence for effective hazard prevention. More importantly, a more comprehensive model of geological structure evolution will be built through multidisciplinary approaches, integrating petrology, geochemistry, geophysics, and geological dating. This research aligns with the Belt and Road Initiative by prioritizing geological hazard prevention and advancing fundamental research on geological structures, carrying profound scientific and strategic implications.
Carbon participates in the global carbon cycle in various forms in the ocean, with total organic carbon (TOC) buried in marine sediments playing a crucial role. As a transition zone characterized by high physical energy and productivity, marginal seas store more than 80% of the organic carbon in the global ocean. Covering a total area of about 4.7 million square kilometers, China’s marginal seas possess significant carbon storage capacity and potential. With the implementation of China’s “Dual Carbon” initiative, research on marine carbon storage has become a prominent topic in recent years. This review summarizes the distribution characteristics of organic carbon in the sediments of China’s marginal seas, revealing a decreasing tendency from the Bohai Sea to the South China Sea. Notably, organic carbon content in coastal waters and near estuaries is significantly higher than in the deep sea. In addition, the main sources, influencing factors, and storage potential of organic carbon are analyzed. Moreover, the review provides an outlook on potential future research directions, aiming to offer insights for the related work on marine carbon storage and the carbon cycle in China’s marginal seas.
Estuarine and coastal waters, serving as critical interfaces between terrestrial and marine ecosystems, play a pivotal role in the biogeochemical cycling of nitrous oxide (N2O), a potent greenhouse gas with significant impacts on global climate change. This review synthesizes current knowledge on the distribution patterns of N2O in estuarine and coastal regions, the key microbial metabolic pathways driving N2O emissions—including nitrification, nitrifier denitrification, incomplete denitrification, and coupled nitrification-denitrification—as well as the methodologies for quantifying N2O production and consumption. Additionally, we examine the environmental factors influencing N2O emissions. A deeper understanding of N2O biogeochemical cycling in these waters is crucial for developing effective strategies to mitigate N2O emissions and their contribution to global warming.
Coastal wetlands are mainly waters with a depth of less than 6 m during low tide and their coastal wetted areas. It includes permanent water bodies, intertidal zone and coastal low-lying areas with a water depth of no more than 6m. Wetlands have values such as regulating flows, preventing seawater intrusion, supplementing the sedimentation of nutrients from groundwater, regulating climate, maintaining biodiversity, protecting coasts, carbon sequestration and storage, developing ecological tourism, and undertaking education and scientific research. The global coastal wetland area is approximately 142000000 hm2, and China has approximately 5940000 hm2 at present. With the rapid growth of population, socio-economic development, and industrialization and urbanization processes in coastal areas, the global coastal wetland ecosystems are being severely degraded, and comprehensive protection measures are urgently needed. This article summarizes the technological progress of coastal ecological restoration and environmental optimization both domestically and internationally, and analyzes relevant achievements and cases. It summarizes the characteristics and advantages of China's coastal wetland ecological restoration technology, especially the new achievements made ever since the implementation of the Beautiful China Ecological Civilization Project, which has important reference significance and demonstration role for coastal ecological restoration and environmental optimization, and proposes suggestions and promotion measures for ecological restoration and environmental optimization of the China's coastal wetlands, to support the construction of the national “Carbon Peaking and Carbon Neutrality” strategy and sustainable development of marine economy.
With the growing global demand for clean energy, hydrogen energy, as an important renewable energy reserve, has garnered widespread attention for its storage technology. Onshore hydrogen storage systems pose risks such as hydrogen leakage, drinking water contamination, and catastrophic injuries. In contrast, offshore geological environments are relatively stable and well-sealed, leading to widespread attention to and rapid development of offshore hydrogen storage technology. Currently, the main underground gas storage technologies include salt caverns, aquifers, and depleted oil and gas reservoirs. Salt cavern gas storage has been operating for many years in Europe and the USA and has a relatively mature technical foundation. However, there are no suitable locations for constructing salt caverns along China’s coast, which limits the build-up of salt cavern hydrogen storage to inland regions. However, China’s coastal areas have abundant underground aquifers and oil and gas reservoirs, necessitating timely related geological research to promote the development and application of relevant technologies in different marine areas and the comprehensive development of the hydrogen energy industry. Developing offshore hydrogen storage technology requires not only integrating the unique geological conditions of the margin with the special physical and chemical properties of hydrogen, but also considering geological, hydrological, biochemical, and mineralogical factors to ensure a rational planning and safe operation, in addition to using the latest geophysical methods in site selection. Looking ahead, offshore hydrogen storage technology will not only provide theoretical support for the development of renewable energy technologies in China but also play a significant role in promoting a low-carbon, green, and sustainable development.
Seaweed plays an important role as a primary producer in the ocean, contributing significantly to carbon capture and sequestration. It serves as an effective approach for achieving ocean carbon negative emissions. Seaweed has a vast cultivable area and a high capacity for carbon fixation and sequestration. Through the synergistic effects of biological carbon pump and microbial carbon pump, seaweed has the potential to become a vanguard for achieving negative emissions in the marine aquaculture. Based on the seaweed bioremediation technology, resource conservation technology, and ecological enhancement technology, it is possible to increase the resources of both cultivated and wild macroalgae, improve marine habitats, conserve fishery resources, and promote the development of ocean carbon sink fisheries. By utilizing seaweed green feed technology, it is possible to reduce greenhouse gas (e.g., methane) emissions from economic aquaculture and livestock animals. The large-scale cultivation and green, low-carbon utilization of seaweed can significantly contribute to the development of high-quality marine aquaculture and marine ecological security. Currently, although it is essential to focus on the theory of microbial carbon pump and negative emissions, as well as the development of carbon sequestration technologies in the seaweed ecosystem, we believe that it is necessary to establish accounting standards and methodologies for seaweed carbon sequestration and realize the value-added seaweed eco-products based on the full life cycle. The development of theoretical and technological approaches for macroalgae negative emissions is beneficial for implementing the national dual carbon strategy, and has important scientific significance and application potentials for achieving high-quality development of marine aquaculture and livestock based on coordinated land and marine development in China and the United Nations' sustainable development goals.
With the rapid degradation of coral reefs due to global warming and anthropogenic impacts, implementing the measures of conservation and restoration for coral reefs are extremely urgent. The genetic diversity and connectivity of coral populations can reflect their adaptive potential and resilience when responding to environmental stresses, and is a key scientific basis for the restoration and management of coral reef ecosystem. This review aims to identify studies on the population genetics of scleractinian corals in typical marine areas, and discusses the factors that may affect the genetic structure of corals. In general, most of studies are concentrated in regions such as the Great Barrier Reef and the Caribbean. Microsatellite markers still remain the most widely used molecular markers. Breeding mode, isolation-by-distance, isolation-by-environment and human activities are significant factors affecting the genetic structure and genetic diversity of corals. Finally, this review analyzes the current problems and development trends of the population genetics of scleractinian corals in the South China Sea, with expectation to providing reference for the protection and restoration of coral reefs in China.
Typical tropical marine ecosystems are composed of unique habitats and organisms, such as coral reefs, mangroves and seagrass beds. These ecosystems are mainly distributed in tropical and subtropical marine areas worldwide. It is characterized by high material cycling efficiency, unique ecological functions, rich biodiversity and extremely high productivity, and thus a key object of marine scientific research and resource utilization. Under the multiple pressures of human activities and global changes, its degradation trend has become increasingly prominent. How to restore the function of these typical ecosystems and maintain their sustainable development for the benefit of mankind has attracted increasing amounts of attention from the academic community and the international society. In this paper, the distribution patterns, degradation trends and influencing factors of such typical marine ecosystems in the world are described, with an emphasis on the distribution patterns and biodiversity characteristics of coral reef, mangrove and seagrass bed ecosystems in China. Focusing on coral reef ecosystems, this paper discusses the causes of degradation in the ecosystems and relevant action measurements for restoration and protection in China. According to the global action plan for biodiversity conservation and the actual situation of China, countermeasures and suggestions for the restoration, reconstruction and protection of the typical marine ecosystems were proposed: 1) Establishment of a research center for typical ecosystems in the South China Sea, an intelligent monitoring system and database, and an expert think tank; 2) establishing a demonstration zone for the restoration and protection of the typical marine ecosystems, and inviting experts from multiple disciplines to work together on research-experimentation-demonstration-estimate--promotion-monitor; and 3) optimizing policies and regulations, strengthening law enforcement and management, increasing efforts in science popularization and education, raising public awareness of environmental protection, and promoting conscious social actions. This study aims to provide references for strengthening the conservation and management of typical marine ecosystems and biodiversity, maintaining their sustainable development and implementing the 30×30 goals of the Kunming-Montreal Global Biodiversity Framework.
The health of aquaculture ecosystem and the ecological effects of aquaculture activities have been paid increasing attentions in recent years. As an important part of marine aquaculture ecosystem, ciliates play a key role in matter cycling and energy flow in aquaculture water. In this paper, the research progress about ciliates in mariculture water was reviewed. The biodiversity of ciliates, ciliates diseases, the impact of aquaculture activities on ciliates, and the indication of ciliates to aquaculture environment were introduced. In addition, the limitations of past studies are considered, and the potential research hotspots are prospected for ciliates in aquaculture. This review is aimed at providing some updated information on the ecological effects of mariculture and offering available reference for further understanding the ecological role of ciliates in mariculture.
Bioclastic sediments are an important part of marine sediments, and the motion characteristics are the key to study their depositional process. From the characteristics of bioclastic sediments, we summarize the two main characteristics of shape and internal pore space that affect sediment motion. From the experimental studies of settlement, inception and bank evolution, the influence of bioclastic sand properties on sediment motion characteristics was analyzed. Existing studies have only explored the effect of shape on the motion of single-particle bioclastic sediments and lacked the exploration of the motion of clusters of particles. Due to the limitation of the research tools, the influence of internal pore properties on the motion of bioclastic sediments was not discussed. In the future, we should take into account the shape of bioclastic sediments and internal porosity characteristics in the context of oceanic hydrodynamic conditions to characterize the motion of bioclastic sediments, to quantify the influence of the characteristics of bioclastic sediments, and to apply the results to the practical application in order to predict the evolution of the geomorphology of the shore and beach in the environment of bioclastic sedimentation.
Black carbon is one of the carbonaceous materials, it exists ubiquitously in the environment and could be resistant to oxidation and decomposition. Black carbon might strongly affect the global carbon cycle as an important component of recalcitrant organic carbon. The current discrepancy of marine black carbon budgets indicates that there are unknown sources or buried pathways of black carbon in the ocean. It has been confirmed that marine extreme environments, such as abyssal trenches, hydrothermal vents and cold seeps, may be important sources or sinks of marine black carbon with the continuous deepening of the research on black carbon in these environments. In this review, the geochemical characteristics of black carbon in extreme marine environment are summarized. It is found that the unique “V”-shaped terrain of the abyssal trenches is conducive to the accumulation of materials, in which the black carbon is older than the syn-sedimentary organic carbon, and the annual buried amount of black carbon is about (1.0±0.5) Tg. The high-temperature fluid in hydrothermal vents forms in-situ authigenic black carbon by “burning” organic matter, and its annual contribution to the ocean is about 1.6~9.7Tg, which is an important source of marine black carbon. The source and sink process of black carbon in cold seeps remain unclear, but the high abundance of anaerobic methanotrophic archaea in these areas has recently been proved to directly produce black carbon, and its carbon isotope value is negatively below -60‰. As the only microbial source of black carbon found so far, it is an important supplement to the traditional understanding of black carbon types. The overall framework of marine black carbon source and sink process has been established notwithstanding, there is a lack of direct morphological observation and characterization of black carbon in marine extreme environments. It is necessary to clarify the ratio between terrestrial black carbon input and marine authigenic black carbon in extreme marine environments, to further understand the source and sink process of marine black carbon and explore the role of extreme environmental black carbon in marine black carbon budgets in the future.
Coral reef ecosystems play a crucial role in global carbon cycling and climate change. They serve as potential blue carbon sinks, with coral reefs in China covering approximately 11% of the global area. The annual carbon sequestration of these reefs is estimated to be 3.5×106~4.5×106 t. The total carbon storage capacity of coral reef ecosystems is immense, and they have significant potential value as carbon reservoirs in carbon trading. This article provides a review of carbon sequestration processes and storage mechanisms in coral reef ecosystems, including carbonate pumping, biological pumping, and microbially-mediated carbon pumping. The research progress on these three carbon pumps is discussed. Additionally, the article highlights the limitations and challenges in current research and proposes future research directions, aiming to provide scientific basis for the conservation and management of coral reef ecosystems in the South China Sea.
Coral reef ecosystems are important components of marine ecosystems and play a crucial role in maintaining marine ecological balance and biodiversity. This article summarizes the current international and domestic development status of coral reef ecology through literature review. The major international research focuses include global change and coral reef ecosystems, establishment and maintenance of coral symbiosis, development and evolution of coral reef biotic systems, coral reef biodiversity and species distribution patterns, as well as coral reef ecosystem conservation and management. The major domestic research focuses include global change and coral reef ecosystems, coral-algal symbiosis under global change, diversity of coral symbiotic relationships, human activities and the South China Sea coral reef ecosystem, and coral reef biodiversity and community patterns. The future development trends in coral reef ecology research will emphasize the coral and coral reef ecosystems under the context of global change, coral symbiotic mechanisms, marginal coral reefs, and coral reef conservation and restoration. Future research in coral reef ecology in China should enhance global perspectives, strengthen domestic and international collaborations, explore underlying mechanisms, improve systematic research, and enhance coral reef conservation and restoration studies.
Mucus-feeding pelagic tunicates are widely distributed in the open ocean and coastal waters, which have very high rates of reproduction, and the ability to form massive blooms. In this review, we provide a qualitative overview of the combination of high particle consumption and swarms of pelagic tunicates led to accumulate at the ocean floor as jelly-POM (particulate organic matter), substantial contributions to vertical export fluxes. As well as the swarms in relation to environmental drivers and unique life-history adaptation, its role in pelagic-benthic coupling, structure and energy flow of marine food web by selecting feeding are reviewed. Because pelagic tunicates have high filtering rates and efficiencies and can reach great abundances, they have the potential to remove a significant fraction of shelf water column primary production, are exported via mucous aggregates, fecal pellets, and jelly falls sinking to depth or restructure shelf pelagic food webs. The study of jelly-falls represents a major challenge in the understanding of the biological pump mainly due to technical/sampling hurdles, the ecological significance of pelagic tunicate blooms, for instance, the rate of this downward carbon flux may be further enhanced through in-situ observations on pelagic tunicates’ diel vertical migrations together with quantitative net catches. Future work should pay more attention to the coupling between fine scales of hydrodynamic grazing and breeding rates under in situ conditions, and link bloom impact on carbon cycling to more dimensions of the physical, chemical, and biological ocean environment, in order to more accurately assess the efficiency of the jelly carbon pump and its response to global change.
Mangrove endophytic fungi has evolved a unique metabolic pathway due to its high salt, high temperature, strong light and anoxic living environment, and then produced a large number of secondary metabolites with rich species, novel structure and significant activity, making the secondary metabolites of mangrove endophytic fungi a research hotspot in recent years. In the field of mangrove endophytic fungi, Aspergillus and Trichoderma are two genera that have been studied frequently. This paper reviews the recent advance on the chemical structure and biological activity of new secondary metabolites of the endophytic fungi of genus Aspergillus from mangrove from January 2018 to October 2022 and the endophytic fungi of genus Trichoderma from mangrove from January 2015 to October 2022, summarizes them by polyketones, alkaloids, terpenoids and other compounds, and highlights the challenges in the current research. It can provide reference and guidance for the future study of mangrove endophytic fungi.
The material and energy exchange at the air-sea interface is an important cause of global climate and ecological environment change. As the largest shelf margin sea in China and the Northwest Pacific Ocean, atmospheric deposition plays an important role in the exogenous input of the South China Sea. With the continuous and rapid economic and social development of the surrounding countries in the South China Sea, the transport of anthropogenic pollutants to ocean through atmospheric deposition is increasingly enhanced, which is bound to have a non-negligible impact on the ecological environment of the South China Sea. Based on the research reports of atmospheric deposition of biogenic elements, micro-trace elements and new pollutants microplastics in the South China Sea in the past nearly 30 years, this paper systematically summarized the concentrations, fluxes and influencing factors of atmospheric dry and wet deposition in the South China Sea, and analyzed the eco-environmental effects of atmospheric deposition in the South China Sea. The results show that 1) The concentration of atmospheric particulates in the South China Sea is lower than that in the east coast of China, and there is almost no acid rain deposition. However, the atmospheric carbonaceous aerosol component concentration and deposition in the South China Sea are at a high level due to the influence of biomass burning in Southeast Asia and fossil fuel combustion emissions in China. 2) Nitrogen is the dominant nutrient in the atmospheric dry and wet deposition in the South China Sea, and the proportion of nitrogen species varies greatly in different sea areas, resulting in strong imbalance of nutrient structure in atmospheric deposition. 3) The solubility of anthropogenic metal elements in aerosols is high, and most of them in the form of wet deposition. Aerosol microplastics mostly exist in the form of fiber. Meteorological conditions (precipitation, wind speed, etc.) and source emission intensity are the main factors controlling atmospheric component concentration and deposition flux. 4) Atmospheric nitrogen deposition accounts for about 20% of the total nitrogen input in the sea surface of South China Sea. The addition of nitrogen will aggravate the hypoxia and acidification of the offshore, and nutrient deposition plays an important role in the explosive proliferation of phytoplankton. Atmospheric deposition will have multiple and complex impacts on South China Sea, an oligotrophic ecosystem, which is closely related to hydrologic conditions, initial nutrient status, phytoplankton groups, atmospheric composition and deposition characteristics. In the future, it is suggested that the researchers should pay more attentions to the depth and breadth of the research, focus on the precise and regular monitoring of the dry and wet deposition of various atmospheric components, especially organic nitrogen and phosphorus species and new pollutants, and fully explore the influence and feedback mechanism between the atmospheric deposition of biogenic elements and micro-trace elements and the South China Sea ecosystem from the perspective of interdisciplinarity. Atmospheric deposition is an important part of biogeochemical cycle in the South China Sea, and its impact on the ecological environment is a "double-edged sword". With the continuous enhancement of atmospheric deposition of terrigenous species in the South China Sea in the future, this effect will become more complex and far-reaching.
Human-induced emissions of greenhouse gases such as carbon dioxide (CO2) are the main drivers of global warming. Global warming poses a serious threat to the security of food, water resources, energy, economy, and other fields. Alleviating global warming is imperative. Not only does it require massive greenhouse gas emissions reduction, but also large-scale deployment of carbon dioxide removal (CDR) or negative emissions techniques to intentionally remove CO2 from the air and sequestrate it for a long period so that to decrease global net CO2 emissions to zero as soon as possible, and achieve "carbon neutrality". The ocean accounts for 70% of the earth's surface area and is the largest active carbon pool. It has a huge potential to absorb CO2. Ocean-based CDR is necessary to achieve carbon neutrality. The research on the theory, method, and technology of ocean CDR has become a hot spot and frontier field. At present, the knowledge of ocean CDR is still relatively limited, and there is a large space for development. The urgent need to mitigate global warming is promoting the rapid development of the basic theory of marine carbon sinks and ocean CDR research, and original progress is emerging. This paper mainly summarizes the theoretical basis of the Iron-Aluminum Hypothesis and discusses the potential of ocean aluminum fertilization as a CDR strategy. The iron-aluminum hypothesis indicates that aluminum can enhance carbon fixation by phytoplankton in the upper ocean, reduce the decomposition rate of biogenic carbon, improve the efficiency of the biological pump, increase carbon export and sequestration to the deep sea, regulate marine carbon sinks, and affect the concentration of CO2 in the atmosphere. Thereby, as well as iron, aluminum may be a key factor in influencing historical and modern climate changes. Aluminum improves the efficiency of iron use and carbon export to the deep ocean, which can make up for the shortage of artificial ocean iron fertilization, and endow ocean aluminum fertilization with the potential to become a new CDR method and technology based on natural carbon sinks. Despite its potential high efficiency, ocean aluminum fertilization as a CDR method is still nascent. We suggest further study on the mechanisms underlying the roles of aluminum in enhancing marine carbon sinks from the three aspects 1) carbon fixation by marine phytoplankton in the upper ocean, 2) biogenic carbon export to the deep ocean, and 3) long-term carbon sequestration, and thus to strengthen the theoretical basis of iron-aluminum hypothesis and ocean aluminum fertilization. We also propose to verify the CDR efficacy of ocean aluminum fertilization and its potential environmental impacts at different temporal and spatial scales. The above two works are expected to provide basic scientific knowledge for the development and application of ocean aluminum fertilization as a CDR strategy.
As the unique deep channel that connects the South China Sea (SCS) with the western Pacific Ocean, Luzon Strait is also the key oceanic passage that modulates the SCS circulation and its thermodynamic characteristics. Influenced by large-scale western boundary current, meso-scale eddies, tropical cyclones and other factors, Luzon Strait transport (LST) exhibits significant multi timescale variability. Tropical cyclones are strong and localized low-pressure weather systems that occur frequently in the area, therefore, understanding the dynamic connection between tropical cyclones and LST is one of the most essential topics in oceanography research. This study reviews the research progress in the characteristics of tropical cyclones near the Luzon Strait and its impact on the Kuroshio, ocean circulation and LST, and reveals their recent development. We further suggest that the future study should focus on the modulating mechanisms of the tropical cyclones on the LST and evaluate their contributions to the interannual variations of LST.
Microbial nitrogen fixation is a crucial part of nitrogen cycling in mangrove ecosystems, it plays an essential role in the nitrogen nutrient supply and primary productivity improvement of ecosystem. This paper reviewed the diazotrophic community structure, nitrogen fixation rate, and the main measurement methods of nitrogen fixation in mangrove ecosystems. We also explored the application of nitrogen-fixing microorganisms in mangrove restoration and the ecological indicators of nitrogen-fixing microorganisms for mangrove habitats, emphasized the vital roles of diazotrophs in coupling carbon, nitrogen, and sulfur cycles in mangrove wetlands, and highlighted new perspectives for nitrogen-fixing microorganisms in the mangrove ecosystem.
Sea Cucumbers play an important role in marine ecological system and have edible and medicinal values. At present, wild resources of sea cucumbers are greatly depleted in China, and artificial breeding of sea cucumbers provides an essential way to restore the population resources. Understanding the hormones that regulate spawning behaviors of sea cucumbers has great significance for the development of artificial injection hormone. We reviewed the hormones found in sea cucumbers that can regulate their spawning behaviors, and we also provide some new perceptions for the future research. The review can provide some valuable references for revealing the key spawning mechanism of sea cucumbers and developing the artificial spawning induction by injecting hormones.
Artificial reefs are submerged structures artificially placed on the seabed to mimic some characteristics of natural reefs. They are able to exert the functions of enhancing the proliferation of fishery resources, promoting the restoration of marine habitats and supporting coastal recreation. Its origins date back to thousands of years, but systematic research and applications on artificial reefs only began in the last century. In recent years, with the increasing number of artificial reef studies, a large number of new materials, new structures, new methods and new applications have been proposed and practiced. By reviewing the research progress of artificial reefs in China and abroad, the current situation in this field is reviewed from three aspects: the design, research and application of artificial reefs. The research and application direction of artificial reefs in the future are prospected, aiming to guide the future relevant works on artificial reefs in China.
Continuous measurement technology of suspended sediment concentration is the most fundamental requirement in the research fields of hydraulics, environmental science, estuarine and coastal science, as well as marine science. The current popular technical routes including optical backscattering and transmission, specular reflection, remote sensing, acoustic backscattering and transmission attenuation, tuning fork resonance, pressure difference and gamma-ray attenuation and other principles of technical methods were summarized in this paper. The main advantages and problems of each technical method are then discussed, and the future research focus and development direction are prospected as: (1) the principle of optical backscattering is the optimal technical route for low-cost, miniaturized, and high-time-frequency measurement of suspended sediment concentration, and is necessary to focus on range expansion and particle size sensitivity weakening study; (2) low uncertainty suspended sediment concentration profile measurement relies on the development of the acoustic backscattering technical route; (3) the tuning fork resonance technical route is particularly suitable for ultra-high range application scenarios under turbid current and fluid mud conditions; (4) integrate multi-technology sensors and use the artificial intelligence algorithms to replace traditional inverse theory model, etc.
Green sea dyke represents a new concept of coastal defense, which combines traditional engineering structure with coastal ecosystem, to cope with the future trend of sea level rise and storm intensification. Before its application, however, the feasibility of such a system must be tested for low-lying coastal areas, where the risk of storm surge, storm-induced waves and shoreline erosion is greatest. The major issue is associated with the process of wave attenuation by the ecosystem and the way of using the ecosystem within the sea dyke system. For many years, wave energy dissipation has been an important research field for tidal flats, a typical environment of low-lying coasts, as well as beaches and rocky coast environments. Theoretical analysis, field observation and physical-mathematical modelling show that the coastal ecosystem indeed plays a significant role in wave energy dissipation: (1) resuspension and fluid mud movement dominate over bed friction in the mud area, in terms of wave height reduction; (2) wave attenuation occurs due to bed friction and bedload transport on the silt-sand flat at the lower part of the tidal flat, while on the upper mudflat it is caused mainly by re-suspension and suspended, fine-grained sediment transport; (3) in the vegetated ecosystems such as salt marsh, mangrove and seagrass beds, the efficiency of plants in reducing flow velocity and dissipating wave energy is higher than that of bare flats, due to plant morphological resistance and stem movement; and (4) wave attenuation is high when passing through biological reefs (e.g., coral and oyster reefs), especially during storms, with bed surface friction and wave breaking being the major mechanisms. Although the wave attenuation theory has been established, the optimization of the way the ecosystem is used within the sea dyke system requires further investigations, especially the techniques of ecological niche reconstruction on eroding coasts and the design of the sea dyke to improve structure safety. The relevant scientific problems include: adaptive biology for salt marsh plants and oysters in conjunction with hard engineering; stability of ecosystem in response to future environmental change; spatial configuration of ecosystem in the green sea dyke and the match between the ecosystem life cycle and the temporal scales of storm events; and the optimization of the sea dyke configuration, on the basis of the equilibrium coastal profile theory.
The staff at the South China Sea and Adjacent Seas Data Center, which is a sub-center of the National Earth System Science Data Center, has developed South China Sea ocean database by combining the advantages of ecological environment research domain, the tropical marine environment research domain and the marginal sea and ocean geology research domain, to promote open access and effective utilization of ocean data. In this paper, we introduce our practice in the South China Sea and Adjacent Seas Data Center scientific data construction, which is arranged to share the multi-disciplinary, multi-element and multi-scale marine scientific data in the South China Sea and its adjacent water since 1985, including data of hydrology, meteorology, ecology, and geology. This center will provide high-quality data for research of the South China Sea. It will provide basic data for major national strategies, marine economic and social development and related decision making activities.
The coasts of coral reefs and islands are characterized with very complex wave-current dynamics, unique morphology and largely unknown engineering responses, where wave transformation and wave-induced currents have significant impacts on the infrastructure safety, morphological evolution, disaster prevention, and eco-environmental protection. Recent research advances on these topics are reviewed with respect to three spatial scales, e.g., the large-scale long-wave guiding and trapping, the medium-scale hydrodynamics in a reef-lagoon-channel system, and the local wave-structure interaction. This paper includes the descriptions of, specifically, theoretical findings of guided and trapped waves over ocean ridges and around reef islands, two-dimensional horizontal wave basin experiment of a reef-lagoon-channel system, and new methods to estimate wave overtopping and forces on the seawall based on a large-scale wave flume experiment. Further research prospects are also suggested.
Because of their unique habitat and metabolic pathways, marine microorganisms can produce a variety of bioactive substances with novel structures and functions, which make natural products from these marine microorganisms become a research hotspot of new marine drugs. Combining the methods and perspectives of bibliometrics, we review in this paper the research status of natural products from marine fungi and marine bacteria, the artificial synthesis of natural products of marine microorganisms, the biological activity and druggability evaluation of natural products from marine microorganisms, to clarify the current status and development trend of natural products from marine microorganisms.
The development of marine sciences depends on observations. Satellite is one of the most important observation platforms for marine research. Satellite data are of great significance in marine research. Since the beginning of this century, China has successfully launched several satellites dedicated to ocean observations, and preliminarily established a global ocean satellite observation system. According to the basic situation of marine satellite resources at home and abroad, we study and analyze the current situation of the application and development of marine satellite data in China, especially in terms of receiving, processing, management and application of marine satellite data, put forward the scientific research demand for satellite data in China's marine research, and probe into the existing problems and development strategies of the scientific application of marine satellite data in China.
The air-sea turbulent heat fluxes (THFs), including the evaporative latent heat flux and convective sensible heat flux, are key components in air-sea interaction and ocean circulation, which are important for our understanding of the global energy balance, water cycle and climate change. Due to the limitations of observations and numerical simulations, the diurnal variations in THFs are however not accurately known. In this paper, we propose a future research plan toward identifying the mechanisms behind diurnal variations in THFs. With the recent development of traditional buoy observations, new observations (e.g., glider) and newly released atmospheric reanalysis, it is helpful to research the diurnal variations in THFs. Using the combined observations and reanalysis, we investigate the key scientific issues on diurnal variations in THFs under different boundary layer stability based on the bulk formulas and turbulence methods. In the future, we will demonstrate the global basic structures and dominant factors for diurnal variations in THFs, as well as the strength of the diurnal variation associated with the extreme weather processes and climate events. To evaluate accurate magnitudes of THFs for better understanding of diurnal variations, high-frequency surface currents and height-dependent air-sea physical variables will be incorporated into the estimates of THFs in terms of bulk formulas. Innovatively, this study transfers the multi-scale THF variations into the space of boundary layer stability to concentrate on the diurnal variations, which help study the mixed-layer dynamics, upper-ocean ecosystems, energy balance, and climate change.
Mangrove is one of the most important ecological and environmental resources in the world, which can have significant effects including reservation of the organic carbon, accretion of the tidal flat, and protection from ocean hazards. In this study, we reviewed studies of the mangrove tidal flat (MTF) sedimentary dynamics, which involve damp energy and sediment trapping of the MTF, bio-geomorphological behavior of the MTF, and response of the MTF to storm and sea-level rise. We stress that understanding of the MTF sedimentary dynamics should focus on the following scientific questions: attenuation of the coupled dynamics between wave and tidal current along MTF, coupling processes among hydrological dynamics, deposition, geomorphology, and vegetation. Moreover, it is urgent that the study of regional-scale sedimentation processes and driving mechanics of MTF should be intensified in future.
Anaerobic oxidation of methane (AOM) by archaea in marine sediments is gradually recognized by scientists and is regarded as an important biogeochemical process performed by both methanotrophic archaea and sulfate-reducing bacteria. Our analysis of 16S rRNA showed that multiple kinds of Methanoarchaea including AEME-1, AEME-2 and AEME-3 were the players in the AOM process, and these Methanoarchaea were distributed widely in the oxygen minimum zone of the open ocean. Furthermore, AOM process is related to the global environmental change closely. Most methane leaked from cold seeps of deep sea was consummated by Methanoarchaea in the course of penetrating the deposition layer of anoxic zone; so emission of strong greenhouse methane was reduced greatly. The studies of AOM biogeochemical process should be significant for understanding the formation mechanism of clod seep carbonate, controlling the leaking methane from seafloor, exploitation of combustible ice, and so on.
