Benthic habitat mapping is an emerging discipline in the international marine field in recent years,providing an effective tool for marine spatial planning,marine ecological management,and decision-making applications...Benthic habitat mapping is an emerging discipline in the international marine field in recent years,providing an effective tool for marine spatial planning,marine ecological management,and decision-making applications.Seabed sediment classification is one of the main contents of seabed habitat mapping.In response to the impact of remote sensing imaging quality and the limitations of acoustic measurement range,where a single data source does not fully reflect the substrate type,we proposed a high-precision seabed habitat sediment classification method that integrates data from multiple sources.Based on WorldView-2 multi-spectral remote sensing image data and multibeam bathymetry data,constructed a random forests(RF)classifier with optimal feature selection.A seabed sediment classification experiment integrating optical remote sensing and acoustic remote sensing data was carried out in the shallow water area of Wuzhizhou Island,Hainan,South China.Different seabed sediment types,such as sand,seagrass,and coral reefs were effectively identified,with an overall classification accuracy of 92%.Experimental results show that RF matrix optimized by fusing multi-source remote sensing data for feature selection were better than the classification results of simple combinations of data sources,which improved the accuracy of seabed sediment classification.Therefore,the method proposed in this paper can be effectively applied to high-precision seabed sediment classification and habitat mapping around islands and reefs.展开更多
China’s coastal regions,characterized by dense populations and industrial agglomeration,face escalating threats from typhoon disasters.Understanding the evolution of socio-economic exposure to future typhoon landfall...China’s coastal regions,characterized by dense populations and industrial agglomeration,face escalating threats from typhoon disasters.Understanding the evolution of socio-economic exposure to future typhoon landfalls under global change is critical for effective disaster risk management.This study utilizes future typhoon track data simulated by the regional climate model version 4(RegCM4),combined with projected population and Gross Domestic Product(GDP)data for China’s coastal regions under three Shared Socioeconomic Pathways(SSPs:SSP1,sustainability;SSP2,middle of the road;SSP5,fossil-fueled development).We analyze typhoon impact zones for future periods(2030s,2050s,and 2090s)under Representative Concentration Pathways(RCPs:RCP2.6,RCP4.5,and RCP8.5,representing low,medium,and high greenhouse gas emission scenarios,respectively).Exposure levels for 2030,2050,and 2100 are calculated based on the annual average frequency of typhoon impacts during these periods,aiming to quantify the distribution characteristics of typhoon-affected population and GDP in China’s coastal regions.Key findings reveal two high-frequency typhoon im-pact zones:the Taiwan Strait region and the northern Qiongzhou Strait region.Furthermore,under RCP2.6,typhoon impacts may ex-tend to Liaoning,while RCP4.5 and RCP8.5 scenarios indicate potential impacts reaching further north to Heilongjiang.Under RCP4.5,Northeast China will experience the largest typhoon-affected area(43.800×10^(4) km^(2))by the 2030s.High population and GDP exposure concentrates in the Yangtze River Delta,the Pearl River Delta,and the Taiwan Strait coastal areas.Notably,Liaoning’s cumulative ex-posed population may exceed 0.100×10^(8) by 2030 and 2050 under RCP4.5 and RCP8.5 due to typhoon track migration.Given China’s location within the Western Pacific typhoon high-incidence region,the northward expansion of impacts will substantially escalate socio-economic exposure in mid-latitude regions previously at lower risk.These findings underscore the imperative for enhanced disaster pre-vention,mitigation strategies and targeted countermeasure research.展开更多
Understanding the dynamics of vegetation carbon sequestration(VCS)is essential for regional carbon neutrality strategies.This study revealed the spatiotemporal patterns of VCS and its relationship with anthropogenic c...Understanding the dynamics of vegetation carbon sequestration(VCS)is essential for regional carbon neutrality strategies.This study revealed the spatiotemporal patterns of VCS and its relationship with anthropogenic carbon emissions(ACEs)in Shandong Province,China during 2000-2020,and identified the sensitivity factors affecting VCS.The results show that:1)VCS increased consistently from 193.45 million t to 256.41 million t,with high values areas concentrated in the central,northeastern,and southeastern mountainous and hilly regions,while low values were found in water bodies and urban built-up areas.At the city level,Linyi,Yantai,Binzhou,and Jinan experienced the most significant rises-reaching up to 243000 t/yr.At the county level,Pingdu,Qixia,and Yiyuan also showed substantial growth,each exceeding 30400 t/yr.2)Digital Elevation Molde(DEM)was identified as the dominant natural factor influencing VCS distribution,while land use optimization measures,especially afforestation and farmland conversion in sloped terrain,were the primary human drivers of VCS increase.3)Urbanization and carbon neutrality were not mutually exclusive.While urban expansion locally reduced VCS,rural emigration enhanced carbon sinks in surrounding areas,partially offsetting urban losses.This compensatory mechanism supported VCS increases in nearly all cities and 90% of counties.Nevertheless,with ACEs continuing to rise and the offset ratio by VCS declining,achieving carbon neutrality requires regional strategies that integrate with accelerated energy conservation,emission reduction technologies,and energy transition.These findings provide a scientific basis for decomposing carbon neutrality targets across cities and counties in Shandong and a reference for developing localized land use policies in similar regions.展开更多
Marine pollution and overfishing induced the biodiversity loss and ecological degradation of the Beibu Gulf ecosystem in Guangxi,SE China.In an effort to restore the ecosystem and fishery resources,artificial reefs we...Marine pollution and overfishing induced the biodiversity loss and ecological degradation of the Beibu Gulf ecosystem in Guangxi,SE China.In an effort to restore the ecosystem and fishery resources,artificial reefs were deployed in the Beibu Gulf as the marine ranching area and their ecological performance need to be investigated.We constructed Ecopath ecological trophic models for the marine ranching area and a nearby control area to compare their ecosystem throughput and food web structure difference,and to calculate the ecological carrying capacity of various functional groups.Results indicate that the total system throughput of the marine ranching area was significantly higher than the control area,and the majority of system throughput occurred at trophic levelsⅠandⅡin both ecosystems.The system connectance indices for the marine ranching and control areas were 0.27 and 0.32,and the omnivory indices were 0.16 and 0.19,indicating simple food web structures;both areas are in a developmental stage with TPP/TR ratios of 2.69 and 9.36,respectively.Compared to the control area,marine ranching area exhibited a higher system maturity,and the ecological carrying capacity of“large and medium-sized demersal fish”and“other bivalves”functional groups in the marine ranching area increased by 43.83%and 233.62%,respectively,allowing for more high-trophic-level predators and large benthic animals.This study provided a reference for the formulation of fishery management policies in the Beibu Gulf,to maintain ecosystem stability and biodiversity.展开更多
Thermohaline features, spatial extensions, and depths of the antarctic circumpolar deep water, the antarctic bottom water, and the upper layer water near the Prydz Bay （ including the Prydz Bay s.mmer surface water, ...Thermohaline features, spatial extensions, and depths of the antarctic circumpolar deep water, the antarctic bottom water, and the upper layer water near the Prydz Bay （ including the Prydz Bay s.mmer surface water, the antarctic winter water, and the Prydz Bay shelf water ） are analyzed and studied by use of the full depth CTD data obtained in the Southern Ocean near the Prydz Bay during the 1998/1999 austral summer. The northward extension of the shelf water, the thickness of the temperature inversion layer, the minima in the vertical temperature profile and the vertical temperature gradient are interpreted. On the basis of analysis of gravitational potential field, the geostrophic current and the geostrophic volume transport are calculated to determine the location of the strongest current in the zonal circulation near the Prydz Bay and to find the spatial variability of the volume transport in the64° -66.5°S zone. In addition, the central location, the frontal strength, the vertical depth and thickness of the continental water boundary （CWB） are estimated from the CTD data to expound the spatial variability of CWB in the study area （64° -66.5°S, 70° -75°E）.展开更多
Oceanographic surveying has been one of the key missions of the Chinese National Antarctic Research Expedition since 1984. Using the field data obtained in these surveys and the results from remote sensing and numeric...Oceanographic surveying has been one of the key missions of the Chinese National Antarctic Research Expedition since 1984. Using the field data obtained in these surveys and the results from remote sensing and numerical models, Chinese physical oceanographers have investigated the water masses, fronts and circulation patterns in the Southern Ocean. The results of nearly 30 years of research are summarized in this paper. Most oceanographic observations by Chinese researchers have been con- ducted in Prydz Bay and the adjacent seas. CTD （Conductivity Temperature and Depth） data, collected during the past 20 years, have been applied to study several features of the water masses in this region： The spatial variation of warm summer surface water, the northward extension of shelf water, the flow of ice shelf water from the cavity beneath the Amery Ice Shelf, the upweUing of the Circumpolar Deep Water, and the formation of the Antarctic Bottom Water. The circulation and its dynamic factors have been analyzed with dynamic heights calculated from CTD data as well as by numerical models. The structure and strength of the fronts in the southeast Indian Ocean and the Drake Passage were investigated with underway XBT/XCTD （Expendable Bathythermo- graph/Expendable CTD） and ADCP （Acoustic Doppler Current Profiler） data. Their interaunual variations have been determined and the factors of influence, especially the atmospheric forcing and mesoscale oceanic processes, were studied using remote sens- ing data. The dynamic mechanism of the Antarctic Circumpolar Current （ACC） was analyzed by theoretical models. The transport and pattern of the ACC have been well reproduced by coupled sea ice-ocean models. Additional details of ACC variability were identified based on satellite altimeter data. The response of the ACC to climate change was studied using reanalysis data. Prospects for future research are presented at the end of this paper.展开更多
Planktic foraminifera from the calcareous substrate of a ferromanganese crust in the Vityaz Fracture Zone （VFZ）, Central Indian Ridge were studied to reconstruct the early Pliocene paleoceanography of this region. E...Planktic foraminifera from the calcareous substrate of a ferromanganese crust in the Vityaz Fracture Zone （VFZ）, Central Indian Ridge were studied to reconstruct the early Pliocene paleoceanography of this region. Eleven species of planktic foraminifera were encountered, among them Globorotalia menardii, Neogloboquadrina dutertrei, Globigerina bulloides and Globigerinoides tuber are prominent. Predominance of N. dutertrei in the top 3 cm of the carbonate substrate is attributed to an influx of fresh water which eventually triggered their productivity by increasing the nutrient level. The presence of G. bulloides and G. menardii in significant proportions in deeper layers suggests the prevalence of open ocean upwelling. The bulk chemical compositions of the substrate at different depth intervals indicates higher enrichment of trace metals in the upper sections which could have been supplied through oceanic water by the chemical weathering of terrestrial matter during the peak of Pliocene Asian monsoon. Thus, it is concluded that during the early Pliocene the biogenic components of the substrate were distinctly contributed by both upwelling and productivity triggered by an influx of fresh water originating from the intensification of the Asian monsoon during the early Pliocene Period.展开更多
Recent advances in earth science and exploration have made deepwater channel-levee systems a research focus.We collected and analyzed over 10000 km of two-dimensional multichannel seismic data from the offshore Indus ...Recent advances in earth science and exploration have made deepwater channel-levee systems a research focus.We collected and analyzed over 10000 km of two-dimensional multichannel seismic data from the offshore Indus Basin to identify channellevee systems at various hierarchical levels depending on their seismic reflection characteristics.Seismic facies analysis was integrated with well data to map the spatial distribution of channel-levee systems in the offshore Indus Basin across various geological periods,and the factors influencing their development were discussed.These systems within the basin were identified using a developed,refined three-tier classification method.The first-order system consists of multiple spatially stacked complexes,the second-order system continuously developed multistage channel-levee bodies,and the third-order system represents the smallest identifiable sedimentary units on seismic profiles.Our findings demonstrate the evolution of the offshore Indus Basin from a single-stage channel with lateral migration to multistage vertical channel stacking from the Miocene to the Pleistocene.Tectonic activities exert their effect on channel-levee systems through their influence on the relative sea level.They also trigger volcanic or seismic events and affect siliciclastic supply.Warm and humid climate conditions form large river systems,which aid in the transport of terrestrial debris to the basin margin.Most channel-levee systems are assumed to have formed during low sea-level periods.This study offers new insights into the formation and evolution of turbidite sedimentary systems in the offshore Indus Basin and presents a practical classification method for comprehending gravity-flow sedimentary configurations and deepwater hydrocarbon exploration.展开更多
The Indonesian Throughflow(ITF)plays important roles in global ocean circulation and climate systems.Previous studies suggested the ITF interannual variability is driven by both the El Niño-Southern Oscillation(E...The Indonesian Throughflow(ITF)plays important roles in global ocean circulation and climate systems.Previous studies suggested the ITF interannual variability is driven by both the El Niño-Southern Oscillation(ENSO)and the Indian Ocean Dipole(IOD)events.The detailed processes of ENSO and/or IOD induced anomalies impacting on the ITF,however,are still not clear.In this study,this issue is investigated through causal relation,statistical,and dynamical analyses based on satellite observation.The results show that the driven mechanisms of ENSO on the ITF include two aspects.Firstly,the ENSO related wind field anomalies driven anomalous cyclonic ocean circulation in the western Pacific,and off equatorial upwelling Rossby waves propagating westward to arrive at the western boundary of the Pacific,both tend to induce negative sea surface height anomalies(SSHA)in the western Pacific,favoring ITF reduction since the develop of the El Niño through the following year.Secondly,the ENSO events modulate equatorial Indian Ocean zonal winds through Walker Circulation,which in turn trigger eastward propagating upwelling Kelvin waves and westward propagating downwelling Rossby waves.The Rossby waves are reflected into downwelling Kelvin waves,which then propagate eastward along the equator and the Sumatra-Java coast in the Indian Ocean.As a result,the wave dynamics tend to generate negative(positive)SSHA in the eastern Indian Ocean,and thus enhance(reduce)the ITF transport with time lag of 0-6 months(9-12 months),respectively.Under the IOD condition,the wave dynamics also tend to enhance the ITF in the positive IOD year,and reduce the ITF in the following year.展开更多
Homogeneous methods for ecological applications to the nutrient cycle are analyzed,and the results are presented according to the marine ecology work discussed.To do justice to the explanations,the materials are summa...Homogeneous methods for ecological applications to the nutrient cycle are analyzed,and the results are presented according to the marine ecology work discussed.To do justice to the explanations,the materials are summarized,and the methods are discussed and improved for both interested readers and experts in the field.Both the materials and the methods serve informative and popularizing as well as applicable and interpretive purposes and,in order to achieve the widest possible dissemination,are shared under the strict supervision of the earlier individual publications discussed here.The aeolian syntheses quantify the impact of atmospheric deposition of nutrients in the Western Mediterranean as one-twentieth of the baseline vertical fluxes of organic matter,while estimates for the Eastern Mediterranean reach one-eighth.Possible changes and additions in the global ocean are discussed as well as ecosystem updates and their relevance to the specific orography,hydrology and geochemistry associated with the lower trophodynamic degrees of freedom.Finally,the dynamics of the basins are analyzed,with increasing nutrient inputs leading to a top-down control of net plankton growth in the western basin and to an extremely nutrient-poor state in the eastern basin.展开更多
Using literature published from 2010 onwards, this study investigates the ~3 500 km extension of the shallow shelf current in the South China Sea(SCS) during the winter and summer monsoons. This current is later ackno...Using literature published from 2010 onwards, this study investigates the ~3 500 km extension of the shallow shelf current in the South China Sea(SCS) during the winter and summer monsoons. This current is later acknowledged as the South China Sea shallow shelf Current(SCSSC). This current is primarily driven by monsoonal winds, and influenced by regional river plumes [Zhujiang(Pearl) River, Hong River, Mekong River] and the prominent South China Sea Warm Current(SCSWC) and South China Sea Western Boundary Current(SCSWBC). The current exhibits significant seasonal variations in both direction and pattern. During winter, it flows along the northern South China Sea's(NSCS) shelf and splits into two branches at the east of Hainan Island. One branch enters the Beibu Gulf through the Qiongzhou Strait and forms a major cyclonic circulation within the gulf, while the other branch flows southwestward along the southern coast of Hainan Island. These branches converge around 16°N latitude at the east of the Vietnamese shelf, then flow southward along the Sunda Shelf, where they deflect southwestward in “broadband”forms before curving southeastward along the east coast of Peninsular Malaysia(ECPM) and exiting via the Karimata Strait. In summer, the current exhibits a complex pattern. At the Sunda Shelf, it flows northwestward along the ECPM,then deflects northeastward around 6°N latitude, forming the Sunda Shelf's anti-cyclonic eddy(SSE) and causing upwelling on the east coast of Peninsular Malaysia(ECPMU). Near the eastern Vietnamese shelf, the current splits around 11°-12°N latitude into three distinct currents: the southward-flowing Vietnam Current, the northward-flowing Vietnam Meandering Current(VMC), and the southward-flowing SCSWBC. The VMC flows northward and then deflects northeastward south of Hainan Island, continuing northeastward along the NSCS's shelf and exiting through the Taiwan Strait.展开更多
Understanding the seasonal variations of the zooplankton community’s structure in the Western Pacific Warm Pool(WPWP)-the most stable open marine environment in the Pacific Ocean-is crucial to predict the impacts of ...Understanding the seasonal variations of the zooplankton community’s structure in the Western Pacific Warm Pool(WPWP)-the most stable open marine environment in the Pacific Ocean-is crucial to predict the impacts of climate change on the ecosystem.However,knowledge on these variations in this region down to the mesopelagic zone is insufficient.In this study,the environmental DNA(eDNA)metabarcoding method was used to investigate the zooplankton community during summer,autumn,and winter,from the surface to a depth of 1000 m spanning the epipelagic to mesopelagic zones.The zooplankton community structure exhibited seasonal fluctuations at multiple depths except for 200 and 1000 m.In addition,a stronger zooplankton seasonality was particularly recorded in the epipelagic zone than in the mesopelagic zone,which is consistent with the environmental changes.The studied zooplanktons are dominated by medusae and copepods that showed distinct seasonality.At all depths,medusae exhibited greater seasonal variations than the overall zooplankton community,whereas the copepods did not exhibit significant seasonality.The environmental features and the seasons exerted greater influences on the structure of the zooplankton communities than did the spatial factors.The results of this study indicate that eDNA metabarcoding can provide novel insights into zooplankton assemblages due to its ability to capture a rich variety of medusae,which are often underestimated by net collection.展开更多
The spatial variability of mesozooplankton(MZ)community characteristics,with an emphasis on the predominant taxa,copepods,were evaluated between two distinct coastal water environments of Mangalore:the Netravati-Gurup...The spatial variability of mesozooplankton(MZ)community characteristics,with an emphasis on the predominant taxa,copepods,were evaluated between two distinct coastal water environments of Mangalore:the Netravati-Gurupura estuarine system(NGES)and the adjacent nearshore waters(<20 m depth)on the southwest coast of India during winter 2018.The nearshore waters were characterised by uniformly distributed hydrographic properties,particularly in terms of water column temperature,salinity and turbidity.This well-mixed water column likely stimulated increased phytoplankton chlorophyll a concentrations[av.(2.9±2.2)mg/m^(3)],which in turn supported higher MZ biomass[av.(0.4±0.15)mL/m^(3)]and abundance[av.(6889±3387)ind./m^(3)]in the nearshore waters.In contrast,the NGES exhibited highly variable hydrographic conditions,leading to inconsistent chlorophyll a[av.(3.2±3.7)mg/m^(3)],along with significantly lower MZ biomass[av.(0.1±0.2)mL/m^(3)]and abundance[av.(238±339)ind./m^(3)].The MZ community was dominated by herbivorous copepods(HCs),particularly Bestiolina similis,in the entire study region;however,the nearshore waters supported a more diverse taxon.The overall dominance of HCs,e.g.,B.similis and Pseudodiaptomous aurivillii,in the nearshore waters,indicates the presence of stable hydrographic conditions,especially consistently higher salinity and chlorophyll a level.In contrast,the unstable hydrographic conditions in the NGES,primarily reflected in the uneven salinity distributions,likely contributed to the reduced MZ biomass and abundance.The relative increase in the abundance of B.similis observed exclusively in the euhaline zones of the estuary highlights the significant influence of neritic waters.展开更多
This study examines the multi-scale spatio-temporal evolution of drought characteristics in Zhejiang Province.We propose a comprehensive index to identify drought days and events by incorporating three widely used mon...This study examines the multi-scale spatio-temporal evolution of drought characteristics in Zhejiang Province.We propose a comprehensive index to identify drought days and events by incorporating three widely used monitoring indices:the precipitation anomaly percentage,relative humidity index,and standardized precipitation index.The analysis reveals a significant long-term decreasing trend in the frequency of drought days across Zhejiang Province from 1971 to 2020,with a total of 170 drought events being identified.An Empirical Orthogonal Function(EOF)analysis of precipitation anomalies during these events reveals a dominant province-wide monopole mode,alongside a secondary northsouth inverse dipole,a third tripole,and a fourth southwest-northeast inverse dipole.Furthermore,a composite analysis of the drought events demonstrates a widespread increase in temperature across all stations,with a strong spatial correspondence between the temperature anomalies and their associated frequency.The study identifies 21 extreme drought events,characterized by spatially inconsistent precipitation patterns across the entire province.展开更多
Understanding the sediment record during the Little Ice Age(LIA)can help elucidate natural sea ice fluctuation and carbon cycle variability.This study analyzed the grain size composition(including ice-rafted debris),t...Understanding the sediment record during the Little Ice Age(LIA)can help elucidate natural sea ice fluctuation and carbon cycle variability.This study analyzed the grain size composition(including ice-rafted debris),total organic carbon(TOC),total nitrogen(TN)content,and stable isotopic composition(δ13C andδ15N)of the sediment record(approximately 490 a)of core ARC7-R11 in the northern part of the Chukchi Shelf.The sediment grains comprise mostly(>90%)silt and clay components.The grain size composition suggests generally low-energy hydrodynamic conditions across the region,yet reveals a trend of enhancement in hydrodynamics from the bottom to top layers of the sediment core,particularly after the 1940s.It also shows occurrences of seasonal sea ice and retreat of the perennial sea ice margin during warmer periods of the LIA and the post-LIA period.The organic matter content is high throughout the core,with heavierδ13C values and moderate TOC/TN ratios indicating primarily marine origin;the terrestrial input is<37.5%according to the endmember model.The variation trend of marine-derived organic carbon(OC)content is similar to that of summer temperature anomalies;while variation trend of terrestrially derived OC shows significant correlation with that of the number of ice-free days in the southern shelf region,except for the period from approximately 1700s to the 1870s.During the LIA,the TOC content fluctuated and decreased,and the relative contribution of terrestrial OC was higher than during the modern warm period.The amount of OC buried in the sediment has increased with climate warming,especially after the 1940s,reflecting the enhanced ability of sediment to sequester carbon during warmer periods.展开更多
Microplastics(MPs)have garnered significant international scrutiny as an emerging environmental pollutant,constituting one of the four principal global environmental threats and posing potential health hazards to huma...Microplastics(MPs)have garnered significant international scrutiny as an emerging environmental pollutant,constituting one of the four principal global environmental threats and posing potential health hazards to humans.However,data on the impact of MPs on the early life of the commercially important fish remain limited.In this study,polystyrene microspheres(PS-MPs)(1 and 5μm)were used to investigate the effects of MPs on the growth,development,and metabolism in early life stages of large yellow croaker Pseudosciaena crocea.Results indicate that MPs were enriched in the gastrointestinal tract and gills of the fish.In addition,PS-MPs(1μm)exhibited no obvious effects on embryo hatching and heart rates,while increased the mortality rate(23.00%vs.control 14.99%)and decreased the body length(4098.61±447.03μm vs.control with 2827.04±254.75μm)of the larvae at the highest exposure concentration(5×10^(4)items/L).Metabolomics analysis revealed that PS-MPs(5μm)induced mild perturbations in phospholipid metabolism,specifically alterations in phosphatidylethanolamine(PE)levels.These changes influenced the cell membranes of juvenile fish,and consequently elicited inflammatory responses,disrupted lipid homeostasis,and affected other critical physiological processes.Ultimately,these effects may avoid the growth retardation and potential mortality.Therefore,PS-MPs could affect negatively the fish health in the early life stage,which has implications for aquatic ecosystems.展开更多
Because of their effect on climate,carbon dioxide(CO_(2)),methane(CH_(4)),nitrous oxide(N_(2)O),and dimethylsulfide(DMS)are collectively designated as climate-relevant gases(CRGs).CO_(2),CH_(4),and N_(2)O are greenhou...Because of their effect on climate,carbon dioxide(CO_(2)),methane(CH_(4)),nitrous oxide(N_(2)O),and dimethylsulfide(DMS)are collectively designated as climate-relevant gases(CRGs).CO_(2),CH_(4),and N_(2)O are greenhouse gases contributing to global warming(positive climate feedback).Conversely,DMS is involved in the generation of cloud condensation nuclei,thus in the formation of clouds that cool the boundary layer by reflecting incoming solar radiation(negative climate feedback).Despite their scarcity,field observations and model results have demonstrated the essential role of polar oceans in the budget of CRGs.For example,the Southern Ocean represents a substantial CO_(2)sink but a source of N_(2)O and DMS,thereby exerting variable feedback on climate change.Unfortunately,because of the severe environmental conditions at polar latitudes,substantial knowledge gaps remain,for example on the mechanisms underlying CRGs formation or on the strength and distribution of their sources and sinks in the Southern and Arctic Oceans.Here,we review the most recent research results on the distribution,production-loss processes,and abundance variations of CRGs in the polar oceans.We list the remaining knowledge gaps and propose future directions of research on CRGs in the polar oceans,as a useful reference for future studies.展开更多
To explore the geochemical characteristics and genesis of the elements in ferromanganese nodules from the Northwest Pacific,this study analyses the mineral composition,elemental content,occurrence phase and genetic me...To explore the geochemical characteristics and genesis of the elements in ferromanganese nodules from the Northwest Pacific,this study analyses the mineral composition,elemental content,occurrence phase and genetic mechanisms of samples by X-ray diffraction(XRD),inductively coupled plasma-optical emission spectrometry(ICP-OES),inductively coupled plasma-mass spectrometry(ICP-MS)and phase analysis methods.The results show that ferromanganese nodules are mainly hydrogenetic,and Mn/Fe content ratio ranges from 0.95 to 2.05.The major minerals are vernadite(δ-MnO_(2))and amorphous ferric oxyhydroxide(FeOOH),and the secondary minerals include todorokite,birnessite,quartz and plagioclase.Ferromanganese nodules contain high contents of Co(0.24%-0.42%),Cu(0.23%-0.73%),Ni(0.33%-0.86%)and rare earth elements(REEs,1192-1990μg/g),which have positive Ce and negative Y anomalies but no Eu anomaly.A cluster analysis suggests that the elements in ferromanganese nodules can be divided into three groups:hydrogenetic components,including Fe,Ti,Zr,P,Pb,Co,Ba,Sr,V and REEs;diagenetic components,including Mn,Ni,Mg,Zn and Cu;and detrital components,including Al,Na,K and Ca.According to chemical leaching,ferromanganese nodules can be divided into four phases:Na,Ca,Mg and Sr are mainly enriched in the carbonate phase;Mn,Co,Ni and Ba are mainly enriched in the Mn-oxide phase;Fe,P,Ti,Cu,Pb,V,Zn,Zr and REEs are mainly enriched in the Fe-oxide phase;and Al and K are mainly enriched in the residual phase.A combination of the two different methods reveal selective enrichment of metal elements from seawater by ferromanganese nodules,featuring multisource mineralization.Moreover,through ion exchange and adsorption,approximately 71.2%of REEs are enriched in the Fe-oxide phase,15.4%in the Mn-oxide phase and 12.4%in the residual phase,while REE contents in the carbonate phase are relatively low.In addition,under the oxic conditions of seawater,the oxidation of soluble Ce^(3+)to insoluble CeO_(2)together with Fe-Mn minerals results in Ce enrichment in ferromanganese nodules.This study provides a reference for the metallogenesis of ferromanganese nodules from the Northwest Pacific.展开更多
The characteristics of modified Circumpolar Deep Water(mCDW)on the continental shelf in Prydz Bay,East Antarctica,are studied based on hydrographic data obtained by the Chinese National Antarctic Research Expeditions ...The characteristics of modified Circumpolar Deep Water(mCDW)on the continental shelf in Prydz Bay,East Antarctica,are studied based on hydrographic data obtained by the Chinese National Antarctic Research Expeditions across 14 summers from 1999 to 2022.In austral summer,the mCDW upwells along the upper continental slope then intrudes on the continental shelf across the shelf break in a warm tongue that gradually upwells poleward.The mCDW intrusion at the 73°E section is relatively weaker in December and stronger in February while showing significant interannual variability.During strong intrusions(January 2000 and February 2003),the mCDW extends southward to 68°S and upwells to 50 m,whereas the mCDW only reaches the shelf break during weak intrusions(December 2004,January 2006,January 2011,and February 2015).The intensity of the mCDW intrusions correlates strongly with the accumulated wind stress curl(30 days prior)north of the shelf break(73.5°-78.0°E,64.5°-66.0°S).The summertime westerly winds play a key role in regulating the interannual variability of mCDW intrusion onto the continental shelf.A southward shift of the westerly winds promotes the upwelling and southward intrusion of mCDW across the shelf break.In addition,mCDW at 73°E can reach as far as 68°S due to the southward flow of mCDW being hindered by a northward outflowing branch of the coastal current at the Amery Ice Shelf(AIS)front.In austral summer,the mCDW had never been observed at the section along the AIS front;thus,it cannot directly contribute to the basal melting of the ice shelf.展开更多
Polynyas and their adjacent seasonal ice zones(SIZs)represent the most productive regions in the Southern Ocean,supporting unique food webs that are highly sensitive to climate change.Understanding the dynamics of phy...Polynyas and their adjacent seasonal ice zones(SIZs)represent the most productive regions in the Southern Ocean,supporting unique food webs that are highly sensitive to climate change.Understanding the dynamics of phytoplankton and the carbon pool in these areas is crucial for assessing the role of the Southern Ocean in global carbon cycling.During the late stage of an algal bloom,seawater samples at 14 stations were collected in the Amundsen Sea Polynya(ASP)and adjacent SIZ.Using nutrients,phytoplankton pigments,organic carbon(OC),remote sensing data,and physicochemical measurements,as well as CHEMTAX model simulations,we investigated the response of the phytoplankton crops,taxonomic composition,and OC pool to environmental factors.Our analyses revealed that hydrodynamic regimes of the polynya,adjacent SIZs and open sea were regulated by the regionally varying intrusion of Circumpolar Deep Water,photosynthetically active radiation and sea ice melt water.The ASP exhibited the highest seasonal nutrient utilization rates[ΔN=(1059±386)mmol/m^(2),ΔP=(50±17)mmol/m^(2) andΔSi=(956±904)mmol/m^(2)],while the open sea had lower rates.The integrated chlorophyll a(Chl a)concentration at depths of 0–200 m ranged from 20.4 mg/m^(2) to 1420.0 mg/m^(2) and peaked in the polynya.In the study area,Haptophytes Phaeocystis antarctica was the dominant functional group(34%±27%),and diatoms acted as a secondary contributor(23%±14%).The major functional group and particulate OC(POC)contributor varied from diatoms(36%±12%)in the open sea to haptophytes(48%±31%)in the polynya waters.Strong light conditions and microelement limitations promoted the dominance of P.antarctica(low Fe forms)dominance in the ASP.The strong correlations between the POC and Chl a depth-integrated concentration suggest that the POC was primarily derived from phytoplankton,while dissolved OC(DOC)was influenced by consumer activity and water mass transport.In addition,the transport of OC in the upper 200 m of the water column within the ASP was quantified,revealing the predominantly westward fluxes for both DOC[9.0 mg/(m^(2)·s)]and POC[7.2 mg/(m^(2)·s)].The latitudinal transport exhibited the northward transport of DOC[8.1 mg/(m^(2)·s)]and southward transport of POC[4.3 mg/(m^(2)·s)]movement.These findings have significant implications for enhancing our understanding of how hydrodynamics influence OC cycling in polynya regions.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.42376185,41876111)the Shandong Provincial Natural Science Foundation(No.ZR2023MD073)。
文摘Benthic habitat mapping is an emerging discipline in the international marine field in recent years,providing an effective tool for marine spatial planning,marine ecological management,and decision-making applications.Seabed sediment classification is one of the main contents of seabed habitat mapping.In response to the impact of remote sensing imaging quality and the limitations of acoustic measurement range,where a single data source does not fully reflect the substrate type,we proposed a high-precision seabed habitat sediment classification method that integrates data from multiple sources.Based on WorldView-2 multi-spectral remote sensing image data and multibeam bathymetry data,constructed a random forests(RF)classifier with optimal feature selection.A seabed sediment classification experiment integrating optical remote sensing and acoustic remote sensing data was carried out in the shallow water area of Wuzhizhou Island,Hainan,South China.Different seabed sediment types,such as sand,seagrass,and coral reefs were effectively identified,with an overall classification accuracy of 92%.Experimental results show that RF matrix optimized by fusing multi-source remote sensing data for feature selection were better than the classification results of simple combinations of data sources,which improved the accuracy of seabed sediment classification.Therefore,the method proposed in this paper can be effectively applied to high-precision seabed sediment classification and habitat mapping around islands and reefs.
基金Under the auspices of National Key Research and Development Program of China(No.2017YFA0604902,2024YFF1306802)Natural Science Foundation of Fujian Province(No.2022J01497)Open Project of the Strait Meteorology Laboratory(No.2025KF03)。
文摘China’s coastal regions,characterized by dense populations and industrial agglomeration,face escalating threats from typhoon disasters.Understanding the evolution of socio-economic exposure to future typhoon landfalls under global change is critical for effective disaster risk management.This study utilizes future typhoon track data simulated by the regional climate model version 4(RegCM4),combined with projected population and Gross Domestic Product(GDP)data for China’s coastal regions under three Shared Socioeconomic Pathways(SSPs:SSP1,sustainability;SSP2,middle of the road;SSP5,fossil-fueled development).We analyze typhoon impact zones for future periods(2030s,2050s,and 2090s)under Representative Concentration Pathways(RCPs:RCP2.6,RCP4.5,and RCP8.5,representing low,medium,and high greenhouse gas emission scenarios,respectively).Exposure levels for 2030,2050,and 2100 are calculated based on the annual average frequency of typhoon impacts during these periods,aiming to quantify the distribution characteristics of typhoon-affected population and GDP in China’s coastal regions.Key findings reveal two high-frequency typhoon im-pact zones:the Taiwan Strait region and the northern Qiongzhou Strait region.Furthermore,under RCP2.6,typhoon impacts may ex-tend to Liaoning,while RCP4.5 and RCP8.5 scenarios indicate potential impacts reaching further north to Heilongjiang.Under RCP4.5,Northeast China will experience the largest typhoon-affected area(43.800×10^(4) km^(2))by the 2030s.High population and GDP exposure concentrates in the Yangtze River Delta,the Pearl River Delta,and the Taiwan Strait coastal areas.Notably,Liaoning’s cumulative ex-posed population may exceed 0.100×10^(8) by 2030 and 2050 under RCP4.5 and RCP8.5 due to typhoon track migration.Given China’s location within the Western Pacific typhoon high-incidence region,the northward expansion of impacts will substantially escalate socio-economic exposure in mid-latitude regions previously at lower risk.These findings underscore the imperative for enhanced disaster pre-vention,mitigation strategies and targeted countermeasure research.
基金Under the auspices of the National Natural Science Foundation of China(No.42476247,42461015)the Open Research Fund of Key Laboratory of Coastal Science and Integrated Management,Ministry of Natural Resources(No.2024COSIM01)Guangxi Science and Technology Base and Talent Special Project(No.GuikeAD23026194)。
文摘Understanding the dynamics of vegetation carbon sequestration(VCS)is essential for regional carbon neutrality strategies.This study revealed the spatiotemporal patterns of VCS and its relationship with anthropogenic carbon emissions(ACEs)in Shandong Province,China during 2000-2020,and identified the sensitivity factors affecting VCS.The results show that:1)VCS increased consistently from 193.45 million t to 256.41 million t,with high values areas concentrated in the central,northeastern,and southeastern mountainous and hilly regions,while low values were found in water bodies and urban built-up areas.At the city level,Linyi,Yantai,Binzhou,and Jinan experienced the most significant rises-reaching up to 243000 t/yr.At the county level,Pingdu,Qixia,and Yiyuan also showed substantial growth,each exceeding 30400 t/yr.2)Digital Elevation Molde(DEM)was identified as the dominant natural factor influencing VCS distribution,while land use optimization measures,especially afforestation and farmland conversion in sloped terrain,were the primary human drivers of VCS increase.3)Urbanization and carbon neutrality were not mutually exclusive.While urban expansion locally reduced VCS,rural emigration enhanced carbon sinks in surrounding areas,partially offsetting urban losses.This compensatory mechanism supported VCS increases in nearly all cities and 90% of counties.Nevertheless,with ACEs continuing to rise and the offset ratio by VCS declining,achieving carbon neutrality requires regional strategies that integrate with accelerated energy conservation,emission reduction technologies,and energy transition.These findings provide a scientific basis for decomposing carbon neutrality targets across cities and counties in Shandong and a reference for developing localized land use policies in similar regions.
基金Supported by the National Key R&D Program of China(No.2022YFD2401301)the Primary Research and Development Plan of Guangxi Province(No.GuiKe AB21220064)+1 种基金the National Natural Science Foundation of China(Nos.42106102,42306151)the Shandong Postdoctoral Science Foundation(No.SDCXZG202301009)。
文摘Marine pollution and overfishing induced the biodiversity loss and ecological degradation of the Beibu Gulf ecosystem in Guangxi,SE China.In an effort to restore the ecosystem and fishery resources,artificial reefs were deployed in the Beibu Gulf as the marine ranching area and their ecological performance need to be investigated.We constructed Ecopath ecological trophic models for the marine ranching area and a nearby control area to compare their ecosystem throughput and food web structure difference,and to calculate the ecological carrying capacity of various functional groups.Results indicate that the total system throughput of the marine ranching area was significantly higher than the control area,and the majority of system throughput occurred at trophic levelsⅠandⅡin both ecosystems.The system connectance indices for the marine ranching and control areas were 0.27 and 0.32,and the omnivory indices were 0.16 and 0.19,indicating simple food web structures;both areas are in a developmental stage with TPP/TR ratios of 2.69 and 9.36,respectively.Compared to the control area,marine ranching area exhibited a higher system maturity,and the ecological carrying capacity of“large and medium-sized demersal fish”and“other bivalves”functional groups in the marine ranching area increased by 43.83%and 233.62%,respectively,allowing for more high-trophic-level predators and large benthic animals.This study provided a reference for the formulation of fishery management policies in the Beibu Gulf,to maintain ecosystem stability and biodiversity.
基金This study was jointly supported by the National National Science Foundation of China under contract Nos 40376009,40231013 and 49836010the Ministry of Science and Technology of China under contact Nos 2003DIB4J135,2005DIB3J114 and 2006BAC06B02.
文摘Thermohaline features, spatial extensions, and depths of the antarctic circumpolar deep water, the antarctic bottom water, and the upper layer water near the Prydz Bay （ including the Prydz Bay s.mmer surface water, the antarctic winter water, and the Prydz Bay shelf water ） are analyzed and studied by use of the full depth CTD data obtained in the Southern Ocean near the Prydz Bay during the 1998/1999 austral summer. The northward extension of the shelf water, the thickness of the temperature inversion layer, the minima in the vertical temperature profile and the vertical temperature gradient are interpreted. On the basis of analysis of gravitational potential field, the geostrophic current and the geostrophic volume transport are calculated to determine the location of the strongest current in the zonal circulation near the Prydz Bay and to find the spatial variability of the volume transport in the64° -66.5°S zone. In addition, the central location, the frontal strength, the vertical depth and thickness of the continental water boundary （CWB） are estimated from the CTD data to expound the spatial variability of CWB in the study area （64° -66.5°S, 70° -75°E）.
基金supported by the Chinese Polar Environment Comprehensive Investigation and Assessment Programmes (Grant nos.CHINARE2013-04-01,CHINARE2013-04-04)the National High-tech Research & Development Program of China (Grant no.2010CB950301)
文摘Oceanographic surveying has been one of the key missions of the Chinese National Antarctic Research Expedition since 1984. Using the field data obtained in these surveys and the results from remote sensing and numerical models, Chinese physical oceanographers have investigated the water masses, fronts and circulation patterns in the Southern Ocean. The results of nearly 30 years of research are summarized in this paper. Most oceanographic observations by Chinese researchers have been con- ducted in Prydz Bay and the adjacent seas. CTD （Conductivity Temperature and Depth） data, collected during the past 20 years, have been applied to study several features of the water masses in this region： The spatial variation of warm summer surface water, the northward extension of shelf water, the flow of ice shelf water from the cavity beneath the Amery Ice Shelf, the upweUing of the Circumpolar Deep Water, and the formation of the Antarctic Bottom Water. The circulation and its dynamic factors have been analyzed with dynamic heights calculated from CTD data as well as by numerical models. The structure and strength of the fronts in the southeast Indian Ocean and the Drake Passage were investigated with underway XBT/XCTD （Expendable Bathythermo- graph/Expendable CTD） and ADCP （Acoustic Doppler Current Profiler） data. Their interaunual variations have been determined and the factors of influence, especially the atmospheric forcing and mesoscale oceanic processes, were studied using remote sens- ing data. The dynamic mechanism of the Antarctic Circumpolar Current （ACC） was analyzed by theoretical models. The transport and pattern of the ACC have been well reproduced by coupled sea ice-ocean models. Additional details of ACC variability were identified based on satellite altimeter data. The response of the ACC to climate change was studied using reanalysis data. Prospects for future research are presented at the end of this paper.
文摘Planktic foraminifera from the calcareous substrate of a ferromanganese crust in the Vityaz Fracture Zone （VFZ）, Central Indian Ridge were studied to reconstruct the early Pliocene paleoceanography of this region. Eleven species of planktic foraminifera were encountered, among them Globorotalia menardii, Neogloboquadrina dutertrei, Globigerina bulloides and Globigerinoides tuber are prominent. Predominance of N. dutertrei in the top 3 cm of the carbonate substrate is attributed to an influx of fresh water which eventually triggered their productivity by increasing the nutrient level. The presence of G. bulloides and G. menardii in significant proportions in deeper layers suggests the prevalence of open ocean upwelling. The bulk chemical compositions of the substrate at different depth intervals indicates higher enrichment of trace metals in the upper sections which could have been supplied through oceanic water by the chemical weathering of terrestrial matter during the peak of Pliocene Asian monsoon. Thus, it is concluded that during the early Pliocene the biogenic components of the substrate were distinctly contributed by both upwelling and productivity triggered by an influx of fresh water originating from the intensification of the Asian monsoon during the early Pliocene Period.
基金the National Natural Science Foundation of China(Nos.42076220,42206234,42476228)the Laoshan Laboratory Science and Technology Innovation Project(Nos.LSKJ202203404,LSKJ202203401)+2 种基金the Laoshan Laboratory‘14th FiveYear Plan’Major Project(No.2021QNLM020001-1)the Project of China Geological Survey(Nos.DD20230317,DD20230410,DD20190818,DD20191032,DD20160152)the Asia Cooperation Foundation‘China-Pakistan Oil and Gas Resource Potential Assessment and Capacity Training’。
文摘Recent advances in earth science and exploration have made deepwater channel-levee systems a research focus.We collected and analyzed over 10000 km of two-dimensional multichannel seismic data from the offshore Indus Basin to identify channellevee systems at various hierarchical levels depending on their seismic reflection characteristics.Seismic facies analysis was integrated with well data to map the spatial distribution of channel-levee systems in the offshore Indus Basin across various geological periods,and the factors influencing their development were discussed.These systems within the basin were identified using a developed,refined three-tier classification method.The first-order system consists of multiple spatially stacked complexes,the second-order system continuously developed multistage channel-levee bodies,and the third-order system represents the smallest identifiable sedimentary units on seismic profiles.Our findings demonstrate the evolution of the offshore Indus Basin from a single-stage channel with lateral migration to multistage vertical channel stacking from the Miocene to the Pleistocene.Tectonic activities exert their effect on channel-levee systems through their influence on the relative sea level.They also trigger volcanic or seismic events and affect siliciclastic supply.Warm and humid climate conditions form large river systems,which aid in the transport of terrestrial debris to the basin margin.Most channel-levee systems are assumed to have formed during low sea-level periods.This study offers new insights into the formation and evolution of turbidite sedimentary systems in the offshore Indus Basin and presents a practical classification method for comprehending gravity-flow sedimentary configurations and deepwater hydrocarbon exploration.
基金The Fund of Laoshan Laboratory under contract No.LSKJ202202700the Basic Scientific Fund for National Public Research Institutes of China under contract No.2024Q02+1 种基金the National Natural Science Foundation of China under contract Nos 42076023 and 42430402the Global Change and Air-Sea InteractionⅡProject under contract No.GASI-01-ATP-STwin.
文摘The Indonesian Throughflow(ITF)plays important roles in global ocean circulation and climate systems.Previous studies suggested the ITF interannual variability is driven by both the El Niño-Southern Oscillation(ENSO)and the Indian Ocean Dipole(IOD)events.The detailed processes of ENSO and/or IOD induced anomalies impacting on the ITF,however,are still not clear.In this study,this issue is investigated through causal relation,statistical,and dynamical analyses based on satellite observation.The results show that the driven mechanisms of ENSO on the ITF include two aspects.Firstly,the ENSO related wind field anomalies driven anomalous cyclonic ocean circulation in the western Pacific,and off equatorial upwelling Rossby waves propagating westward to arrive at the western boundary of the Pacific,both tend to induce negative sea surface height anomalies(SSHA)in the western Pacific,favoring ITF reduction since the develop of the El Niño through the following year.Secondly,the ENSO events modulate equatorial Indian Ocean zonal winds through Walker Circulation,which in turn trigger eastward propagating upwelling Kelvin waves and westward propagating downwelling Rossby waves.The Rossby waves are reflected into downwelling Kelvin waves,which then propagate eastward along the equator and the Sumatra-Java coast in the Indian Ocean.As a result,the wave dynamics tend to generate negative(positive)SSHA in the eastern Indian Ocean,and thus enhance(reduce)the ITF transport with time lag of 0-6 months(9-12 months),respectively.Under the IOD condition,the wave dynamics also tend to enhance the ITF in the positive IOD year,and reduce the ITF in the following year.
文摘Homogeneous methods for ecological applications to the nutrient cycle are analyzed,and the results are presented according to the marine ecology work discussed.To do justice to the explanations,the materials are summarized,and the methods are discussed and improved for both interested readers and experts in the field.Both the materials and the methods serve informative and popularizing as well as applicable and interpretive purposes and,in order to achieve the widest possible dissemination,are shared under the strict supervision of the earlier individual publications discussed here.The aeolian syntheses quantify the impact of atmospheric deposition of nutrients in the Western Mediterranean as one-twentieth of the baseline vertical fluxes of organic matter,while estimates for the Eastern Mediterranean reach one-eighth.Possible changes and additions in the global ocean are discussed as well as ecosystem updates and their relevance to the specific orography,hydrology and geochemistry associated with the lower trophodynamic degrees of freedom.Finally,the dynamics of the basins are analyzed,with increasing nutrient inputs leading to a top-down control of net plankton growth in the western basin and to an extremely nutrient-poor state in the eastern basin.
基金Long-Term Research Grant Scheme (LRGS:56041)Interaction of Ocean Dynamics With The Climate System of Past,Present,and Future Using Ocean Observation Integrated Data and Numerical Modeling。
文摘Using literature published from 2010 onwards, this study investigates the ~3 500 km extension of the shallow shelf current in the South China Sea(SCS) during the winter and summer monsoons. This current is later acknowledged as the South China Sea shallow shelf Current(SCSSC). This current is primarily driven by monsoonal winds, and influenced by regional river plumes [Zhujiang(Pearl) River, Hong River, Mekong River] and the prominent South China Sea Warm Current(SCSWC) and South China Sea Western Boundary Current(SCSWBC). The current exhibits significant seasonal variations in both direction and pattern. During winter, it flows along the northern South China Sea's(NSCS) shelf and splits into two branches at the east of Hainan Island. One branch enters the Beibu Gulf through the Qiongzhou Strait and forms a major cyclonic circulation within the gulf, while the other branch flows southwestward along the southern coast of Hainan Island. These branches converge around 16°N latitude at the east of the Vietnamese shelf, then flow southward along the Sunda Shelf, where they deflect southwestward in “broadband”forms before curving southeastward along the east coast of Peninsular Malaysia(ECPM) and exiting via the Karimata Strait. In summer, the current exhibits a complex pattern. At the Sunda Shelf, it flows northwestward along the ECPM,then deflects northeastward around 6°N latitude, forming the Sunda Shelf's anti-cyclonic eddy(SSE) and causing upwelling on the east coast of Peninsular Malaysia(ECPMU). Near the eastern Vietnamese shelf, the current splits around 11°-12°N latitude into three distinct currents: the southward-flowing Vietnam Current, the northward-flowing Vietnam Meandering Current(VMC), and the southward-flowing SCSWBC. The VMC flows northward and then deflects northeastward south of Hainan Island, continuing northeastward along the NSCS's shelf and exiting through the Taiwan Strait.
基金Supported by the National Key Research and Development Program of China(No.2022YFC2806805)the National Natural Science Foundation of China(Nos.42076122,42306130)the Digital Deep-sea Typical Habitats Program of China Deep Ocean Affairs Administration(No.DYXZ-02)。
文摘Understanding the seasonal variations of the zooplankton community’s structure in the Western Pacific Warm Pool(WPWP)-the most stable open marine environment in the Pacific Ocean-is crucial to predict the impacts of climate change on the ecosystem.However,knowledge on these variations in this region down to the mesopelagic zone is insufficient.In this study,the environmental DNA(eDNA)metabarcoding method was used to investigate the zooplankton community during summer,autumn,and winter,from the surface to a depth of 1000 m spanning the epipelagic to mesopelagic zones.The zooplankton community structure exhibited seasonal fluctuations at multiple depths except for 200 and 1000 m.In addition,a stronger zooplankton seasonality was particularly recorded in the epipelagic zone than in the mesopelagic zone,which is consistent with the environmental changes.The studied zooplanktons are dominated by medusae and copepods that showed distinct seasonality.At all depths,medusae exhibited greater seasonal variations than the overall zooplankton community,whereas the copepods did not exhibit significant seasonality.The environmental features and the seasons exerted greater influences on the structure of the zooplankton communities than did the spatial factors.The results of this study indicate that eDNA metabarcoding can provide novel insights into zooplankton assemblages due to its ability to capture a rich variety of medusae,which are often underestimated by net collection.
基金the Port and Fisheries Division of the PWD and IWT Department, Government of Karnataka,for providing the research grant for executing the project(SSP 3243)
文摘The spatial variability of mesozooplankton(MZ)community characteristics,with an emphasis on the predominant taxa,copepods,were evaluated between two distinct coastal water environments of Mangalore:the Netravati-Gurupura estuarine system(NGES)and the adjacent nearshore waters(<20 m depth)on the southwest coast of India during winter 2018.The nearshore waters were characterised by uniformly distributed hydrographic properties,particularly in terms of water column temperature,salinity and turbidity.This well-mixed water column likely stimulated increased phytoplankton chlorophyll a concentrations[av.(2.9±2.2)mg/m^(3)],which in turn supported higher MZ biomass[av.(0.4±0.15)mL/m^(3)]and abundance[av.(6889±3387)ind./m^(3)]in the nearshore waters.In contrast,the NGES exhibited highly variable hydrographic conditions,leading to inconsistent chlorophyll a[av.(3.2±3.7)mg/m^(3)],along with significantly lower MZ biomass[av.(0.1±0.2)mL/m^(3)]and abundance[av.(238±339)ind./m^(3)].The MZ community was dominated by herbivorous copepods(HCs),particularly Bestiolina similis,in the entire study region;however,the nearshore waters supported a more diverse taxon.The overall dominance of HCs,e.g.,B.similis and Pseudodiaptomous aurivillii,in the nearshore waters,indicates the presence of stable hydrographic conditions,especially consistently higher salinity and chlorophyll a level.In contrast,the unstable hydrographic conditions in the NGES,primarily reflected in the uneven salinity distributions,likely contributed to the reduced MZ biomass and abundance.The relative increase in the abundance of B.similis observed exclusively in the euhaline zones of the estuary highlights the significant influence of neritic waters.
基金Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LZJMD24D050002)Natural Science Foundation of Zhejiang Province(LZJMZ23D050001,LGF22D050007,LGF19D050001)Zhejiang Province Meteor-ological Science Foundation(2022ZD07)。
文摘This study examines the multi-scale spatio-temporal evolution of drought characteristics in Zhejiang Province.We propose a comprehensive index to identify drought days and events by incorporating three widely used monitoring indices:the precipitation anomaly percentage,relative humidity index,and standardized precipitation index.The analysis reveals a significant long-term decreasing trend in the frequency of drought days across Zhejiang Province from 1971 to 2020,with a total of 170 drought events being identified.An Empirical Orthogonal Function(EOF)analysis of precipitation anomalies during these events reveals a dominant province-wide monopole mode,alongside a secondary northsouth inverse dipole,a third tripole,and a fourth southwest-northeast inverse dipole.Furthermore,a composite analysis of the drought events demonstrates a widespread increase in temperature across all stations,with a strong spatial correspondence between the temperature anomalies and their associated frequency.The study identifies 21 extreme drought events,characterized by spatially inconsistent precipitation patterns across the entire province.
基金supported by the National Science Foundation of China(Grant no.42376064)the Chinese Polar Environment Comprehensive Investigation&Assessment Programs(Grant no.CHINARE 2016-03-02).
文摘Understanding the sediment record during the Little Ice Age(LIA)can help elucidate natural sea ice fluctuation and carbon cycle variability.This study analyzed the grain size composition(including ice-rafted debris),total organic carbon(TOC),total nitrogen(TN)content,and stable isotopic composition(δ13C andδ15N)of the sediment record(approximately 490 a)of core ARC7-R11 in the northern part of the Chukchi Shelf.The sediment grains comprise mostly(>90%)silt and clay components.The grain size composition suggests generally low-energy hydrodynamic conditions across the region,yet reveals a trend of enhancement in hydrodynamics from the bottom to top layers of the sediment core,particularly after the 1940s.It also shows occurrences of seasonal sea ice and retreat of the perennial sea ice margin during warmer periods of the LIA and the post-LIA period.The organic matter content is high throughout the core,with heavierδ13C values and moderate TOC/TN ratios indicating primarily marine origin;the terrestrial input is<37.5%according to the endmember model.The variation trend of marine-derived organic carbon(OC)content is similar to that of summer temperature anomalies;while variation trend of terrestrially derived OC shows significant correlation with that of the number of ice-free days in the southern shelf region,except for the period from approximately 1700s to the 1870s.During the LIA,the TOC content fluctuated and decreased,and the relative contribution of terrestrial OC was higher than during the modern warm period.The amount of OC buried in the sediment has increased with climate warming,especially after the 1940s,reflecting the enhanced ability of sediment to sequester carbon during warmer periods.
基金Supported by the Pioneer and Leading Goose R&D Program of Zhejiang(No.2023C03130)the National Key R&D Program of China(No.2019YFD0901101)+4 种基金the National Natural Science Foundation of China(No.42076169)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(Nos.SL2022ZD203,SL2022MS012)the Zhejiang Provincial Natural Science Founds for Distinguished Young Scientists(No.LR21D060001)the State Key Laboratory of Satellite Ocean Environment Dynamics(No.SOEDZZ1902)the ChinaAPEC Cooperation Fund(No.2029901)。
文摘Microplastics(MPs)have garnered significant international scrutiny as an emerging environmental pollutant,constituting one of the four principal global environmental threats and posing potential health hazards to humans.However,data on the impact of MPs on the early life of the commercially important fish remain limited.In this study,polystyrene microspheres(PS-MPs)(1 and 5μm)were used to investigate the effects of MPs on the growth,development,and metabolism in early life stages of large yellow croaker Pseudosciaena crocea.Results indicate that MPs were enriched in the gastrointestinal tract and gills of the fish.In addition,PS-MPs(1μm)exhibited no obvious effects on embryo hatching and heart rates,while increased the mortality rate(23.00%vs.control 14.99%)and decreased the body length(4098.61±447.03μm vs.control with 2827.04±254.75μm)of the larvae at the highest exposure concentration(5×10^(4)items/L).Metabolomics analysis revealed that PS-MPs(5μm)induced mild perturbations in phospholipid metabolism,specifically alterations in phosphatidylethanolamine(PE)levels.These changes influenced the cell membranes of juvenile fish,and consequently elicited inflammatory responses,disrupted lipid homeostasis,and affected other critical physiological processes.Ultimately,these effects may avoid the growth retardation and potential mortality.Therefore,PS-MPs could affect negatively the fish health in the early life stage,which has implications for aquatic ecosystems.
基金supported the National Natural Science Foundation of China(Grant nos.4227624,42376239 and 42476253)。
文摘Because of their effect on climate,carbon dioxide(CO_(2)),methane(CH_(4)),nitrous oxide(N_(2)O),and dimethylsulfide(DMS)are collectively designated as climate-relevant gases(CRGs).CO_(2),CH_(4),and N_(2)O are greenhouse gases contributing to global warming(positive climate feedback).Conversely,DMS is involved in the generation of cloud condensation nuclei,thus in the formation of clouds that cool the boundary layer by reflecting incoming solar radiation(negative climate feedback).Despite their scarcity,field observations and model results have demonstrated the essential role of polar oceans in the budget of CRGs.For example,the Southern Ocean represents a substantial CO_(2)sink but a source of N_(2)O and DMS,thereby exerting variable feedback on climate change.Unfortunately,because of the severe environmental conditions at polar latitudes,substantial knowledge gaps remain,for example on the mechanisms underlying CRGs formation or on the strength and distribution of their sources and sinks in the Southern and Arctic Oceans.Here,we review the most recent research results on the distribution,production-loss processes,and abundance variations of CRGs in the polar oceans.We list the remaining knowledge gaps and propose future directions of research on CRGs in the polar oceans,as a useful reference for future studies.
基金The Fund of Laoshan Laboratory under contract No.LSKJ202203602the National key R&D Program of China under contract No.2022YFC2803600the Taishan Scholarship from Shandong Province.
文摘To explore the geochemical characteristics and genesis of the elements in ferromanganese nodules from the Northwest Pacific,this study analyses the mineral composition,elemental content,occurrence phase and genetic mechanisms of samples by X-ray diffraction(XRD),inductively coupled plasma-optical emission spectrometry(ICP-OES),inductively coupled plasma-mass spectrometry(ICP-MS)and phase analysis methods.The results show that ferromanganese nodules are mainly hydrogenetic,and Mn/Fe content ratio ranges from 0.95 to 2.05.The major minerals are vernadite(δ-MnO_(2))and amorphous ferric oxyhydroxide(FeOOH),and the secondary minerals include todorokite,birnessite,quartz and plagioclase.Ferromanganese nodules contain high contents of Co(0.24%-0.42%),Cu(0.23%-0.73%),Ni(0.33%-0.86%)and rare earth elements(REEs,1192-1990μg/g),which have positive Ce and negative Y anomalies but no Eu anomaly.A cluster analysis suggests that the elements in ferromanganese nodules can be divided into three groups:hydrogenetic components,including Fe,Ti,Zr,P,Pb,Co,Ba,Sr,V and REEs;diagenetic components,including Mn,Ni,Mg,Zn and Cu;and detrital components,including Al,Na,K and Ca.According to chemical leaching,ferromanganese nodules can be divided into four phases:Na,Ca,Mg and Sr are mainly enriched in the carbonate phase;Mn,Co,Ni and Ba are mainly enriched in the Mn-oxide phase;Fe,P,Ti,Cu,Pb,V,Zn,Zr and REEs are mainly enriched in the Fe-oxide phase;and Al and K are mainly enriched in the residual phase.A combination of the two different methods reveal selective enrichment of metal elements from seawater by ferromanganese nodules,featuring multisource mineralization.Moreover,through ion exchange and adsorption,approximately 71.2%of REEs are enriched in the Fe-oxide phase,15.4%in the Mn-oxide phase and 12.4%in the residual phase,while REE contents in the carbonate phase are relatively low.In addition,under the oxic conditions of seawater,the oxidation of soluble Ce^(3+)to insoluble CeO_(2)together with Fe-Mn minerals results in Ce enrichment in ferromanganese nodules.This study provides a reference for the metallogenesis of ferromanganese nodules from the Northwest Pacific.
基金supported by the National Natural Science Foundation of China(No.41976217)the National Key R&D Program of China(No.2018YFA0605701).
文摘The characteristics of modified Circumpolar Deep Water(mCDW)on the continental shelf in Prydz Bay,East Antarctica,are studied based on hydrographic data obtained by the Chinese National Antarctic Research Expeditions across 14 summers from 1999 to 2022.In austral summer,the mCDW upwells along the upper continental slope then intrudes on the continental shelf across the shelf break in a warm tongue that gradually upwells poleward.The mCDW intrusion at the 73°E section is relatively weaker in December and stronger in February while showing significant interannual variability.During strong intrusions(January 2000 and February 2003),the mCDW extends southward to 68°S and upwells to 50 m,whereas the mCDW only reaches the shelf break during weak intrusions(December 2004,January 2006,January 2011,and February 2015).The intensity of the mCDW intrusions correlates strongly with the accumulated wind stress curl(30 days prior)north of the shelf break(73.5°-78.0°E,64.5°-66.0°S).The summertime westerly winds play a key role in regulating the interannual variability of mCDW intrusion onto the continental shelf.A southward shift of the westerly winds promotes the upwelling and southward intrusion of mCDW across the shelf break.In addition,mCDW at 73°E can reach as far as 68°S due to the southward flow of mCDW being hindered by a northward outflowing branch of the coastal current at the Amery Ice Shelf(AIS)front.In austral summer,the mCDW had never been observed at the section along the AIS front;thus,it cannot directly contribute to the basal melting of the ice shelf.
基金The National Polar Special Program under contract Nos IRASCC 01-01-02 and IRASCC 02-02the National Natural Science Foundation of China under contract Nos 41976228,42276255,41976227,42176227,and 42076243+1 种基金the International Cooperation Key Project of the Ministry of Science and Technology under contract No.2022YFE0136500the Scientific Research Fund of the Second Institute of Oceanography,Ministry of Natural Resources,under contract Nos JG2011,JG2211,JG2013,and JG1805.
文摘Polynyas and their adjacent seasonal ice zones(SIZs)represent the most productive regions in the Southern Ocean,supporting unique food webs that are highly sensitive to climate change.Understanding the dynamics of phytoplankton and the carbon pool in these areas is crucial for assessing the role of the Southern Ocean in global carbon cycling.During the late stage of an algal bloom,seawater samples at 14 stations were collected in the Amundsen Sea Polynya(ASP)and adjacent SIZ.Using nutrients,phytoplankton pigments,organic carbon(OC),remote sensing data,and physicochemical measurements,as well as CHEMTAX model simulations,we investigated the response of the phytoplankton crops,taxonomic composition,and OC pool to environmental factors.Our analyses revealed that hydrodynamic regimes of the polynya,adjacent SIZs and open sea were regulated by the regionally varying intrusion of Circumpolar Deep Water,photosynthetically active radiation and sea ice melt water.The ASP exhibited the highest seasonal nutrient utilization rates[ΔN=(1059±386)mmol/m^(2),ΔP=(50±17)mmol/m^(2) andΔSi=(956±904)mmol/m^(2)],while the open sea had lower rates.The integrated chlorophyll a(Chl a)concentration at depths of 0–200 m ranged from 20.4 mg/m^(2) to 1420.0 mg/m^(2) and peaked in the polynya.In the study area,Haptophytes Phaeocystis antarctica was the dominant functional group(34%±27%),and diatoms acted as a secondary contributor(23%±14%).The major functional group and particulate OC(POC)contributor varied from diatoms(36%±12%)in the open sea to haptophytes(48%±31%)in the polynya waters.Strong light conditions and microelement limitations promoted the dominance of P.antarctica(low Fe forms)dominance in the ASP.The strong correlations between the POC and Chl a depth-integrated concentration suggest that the POC was primarily derived from phytoplankton,while dissolved OC(DOC)was influenced by consumer activity and water mass transport.In addition,the transport of OC in the upper 200 m of the water column within the ASP was quantified,revealing the predominantly westward fluxes for both DOC[9.0 mg/(m^(2)·s)]and POC[7.2 mg/(m^(2)·s)].The latitudinal transport exhibited the northward transport of DOC[8.1 mg/(m^(2)·s)]and southward transport of POC[4.3 mg/(m^(2)·s)]movement.These findings have significant implications for enhancing our understanding of how hydrodynamics influence OC cycling in polynya regions.
