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
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
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
The tectonic evolution of Borneo and the affiliation between Southern and Northern Borneo remains unclear.The Rajang and Crocker Fan sediments,as one of the largest ancient submarine fans in Southeast Asia have witnes...The tectonic evolution of Borneo and the affiliation between Southern and Northern Borneo remains unclear.The Rajang and Crocker Fan sediments,as one of the largest ancient submarine fans in Southeast Asia have witnessed the tectonic evolution of Borneo since at least the late Mesozoic.In this study,we present laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)U-Pb dating and Hf isotopic results of detrital zircons from the Trusmadi and Crocker formations within the Crocker Fan of Sabah,Northern Borneo.Our results,coupled with previous data,show that the Crocker Fan sediments in Sabah of Northern Borneo display similar age spectra to the Rajang Fan sediments in Sarawak of Central Borneo,with two major age clusters at 130-80 and 280-200 Ma.Further provenance analysis based on mineral shape with a prismatic characteristic and similar detrital zircon Hf isotopes of the two formations illustrates that the Jurassic-Cretaceous and partly Triassic detrital zircons of the Crocker and Rajang Fan sediments were derived from the erosion of contemporaneous magmatic rocks;part of Permian-Triassic ones could be the recycling of the Jurassic deposits in SW Borneo.The initial provenance of these Permian-Triassic detritus could be synchronous magmatic rocks in the Tin belt of the Malay Peninsula.Combining with previous data,we propose that the entire Borneo continent,including both Southern and Northern Borneo,developed a common Mesozoic continental magmatic arc.Moreover,we postulate that the Rajang and Crocker fans formed in a fore-arc extensional rift basin related to the retreat of the subducted Paleo-Pacific Plate beneath the Northern Borneo margin.展开更多
The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved ...The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved N_(2)O from large regions such as the Southern Ocean.To address this deficit,N_(2)O was measured in the Prydz Bay in February 2015 during the 31st Chinese National Antarctic Research Expedition.N_(2)O concentrations(saturation)in the surface layer were generally low(undersaturation with respect to atmospheric equilibrium)and ranged from 13.3 nmol/L to 16.1 nmol/L(83%–102%)at the time of sampling.A comparison of our observations with archived data revealed that no discernible trend in N_(2)O concentrations in the surface waters of Prydz Bay could be detected for the period between 2006 and 2015.Temperature and salinity changes driven by meltwater input were the predominant controls on N_(2)O concentrations in surface waters.At depth,the distribution of N_(2)O concentrations was dominated by production via nitrification in offshore deep waters and vertical convection in the shelf waters,where concentrations were lower and gradients were less steep.Our results suggest a rather unusual pattern of N_(2)O distribution in the Prydz Bay(low N_(2)O in shelf waters compared with the open ocean),providing important insights into the coastal dynamics of N_(2)O in high-latitude polar regions.展开更多
Low iron content is a peculiar feature of marine ecosystems,where microbes have to produce iron-chelating molecules such as siderophores to survive.Very little is known about siderophore-producing bacteria in the ocea...Low iron content is a peculiar feature of marine ecosystems,where microbes have to produce iron-chelating molecules such as siderophores to survive.Very little is known about siderophore-producing bacteria in the oceans.In this study,we screened 1546 strains from marine seawater and sediments,which were deposited in the Marine Culture Collection of China(MCCC),and further analyzed the diversity of positive strains and their potential genes related to iron acquisition.Of the 1546 isolates,856 strains(55.37%)showed positive siderophore-producing activity on the Chrome Azurol Sulfonate(CAS)plates.Among these,isolates from seawater environments had a higher positive proportion(535).Some genera showed a higher proportion(>70%)of positive siderophore producers,such as Alteromonas(89/112),Marinobacter(78/109),Vibrio(21/27),Shewanella(7/8)in the Gammaproteobacteria,Sulfitobacter(17/21),Martelella(5/6)in the Alphaproteobacteria,and Joostella(6/7)in the phylum Bacteroidetes.Siderophore biosynthesis genes,including those for vanchrobactin,vibrioferrin,petrobactin,and aerobactin,as well as transport and iron storage proteins,were also identified in the positive bacterial genomes.The study revealed that a variety of bacterial strains demonstrate the production of siderophores,which could significantly contribute to the iron cycle within marine ecosystems,encompassing both seawater and marine sediments.展开更多
Mussels are common anchoring organisms that adhere to the surfaces of various substrates with their byssus.The adhesion of mussel to substrates is contingent upon the presence of mussel foot proteins,of which Mytilus ...Mussels are common anchoring organisms that adhere to the surfaces of various substrates with their byssus.The adhesion of mussel to substrates is contingent upon the presence of mussel foot proteins,of which Mytilus edulis foot protein-1(Mefp-1)has been identified as the most abundant protein.It has been found that lipids are involved in the mussel adhesion process and can facilitate Mefp-1adhesion.In this research,the adhesion behavior of Mefp-1 on various substrate surfaces under the effect of typical seawater cations with or without the presence of lipid were investigated using a quartz crystal microbalance with dissipation(QCM-D).Results indicate that the presence of cations Ca^(2+),Mg^(2+),Na^(+),and K^(+)leads to varying degrees of reduction in the adhesion performance of Mefp-1 on different substrates.The degree of this reduction,however,was much alleviated in the presence of palmitic acid,which is involved in the mussel adhesion process.Therefore,the involvement of palmitic acid is advantageous for mussel protein adhesion to the substrate surface in the marine environment.This study illustrated the significant contribution of palmitic acid to mussel adhesion,which can help to better understand biofouling mechanisms and develop biomimetic adhesive materials.展开更多
The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle,influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean.However,the impact of ...The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle,influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean.However,the impact of variability in the timing of seasonal sea ice retreat on the flux and composition of sinking particulate matter remains to be elucidated.In this study,we deployed sediment traps in Prydz Bay during the austral summers of 2019/2020 and 2020/2021,noting that sea ice melting occurred approximately one and a half months earlier in the former summer compared to the latter.We analyzed sediment trap data,which included total mass flux(TMF),particulate organic carbon(POC),biogenic silica(BSi),particulate inorganic carbon,and lithogenic particle(Litho)fluxes,as well as the stable isotopesδ^(13)C andδ^(15)N of particulate organic matter(POM).Additionally,we incorporated remote sensing data on sea ice concentration and chlorophyll a.This dramatic delay in sea ice melting timing could result in a significant increase in TMF,BSi and POC fluxes in the summer of 2020/2021 compared to 2019/2020.Elevated BSi fluxes and more ^(13)C-depleted POC in the austral summer of 2020/2021 suggest that the delayed melting of sea ice may have stimulated the productivity of centric diatoms.Furthermore,the higher BSi/POC ratio and more negativeδ^(15)N values of POM,along with a reduced presence of krill in the traps,indicate a diminished grazing pressure from zooplankton,which collectively enhanced the sedimentation efficiency of POC during the austral summer of 2020/2021.These findings highlight the critical role of sea ice melting timing in regulating productivity,flux and composition of sinking particulate matter in the Prydz Bay ecosystem,with significant implications for carbon cycling in polar oceans.展开更多
The inherent asymmetry and diversity of the El Niño-Southern Oscillation(ENSO)pose substantial challenges to its prediction.Potential predictability measures the upper limit of predictability for a certain event....The inherent asymmetry and diversity of the El Niño-Southern Oscillation(ENSO)pose substantial challenges to its prediction.Potential predictability measures the upper limit of predictability for a certain event.Assessing the potential predictability of ENSO across varying phases and intensities with sophisticated climate models is crucial for understanding the upper limits of forecasting capabilities and identifying room for future enhancement.Based on the hindcast dataset with a recently developed ensemble forecasting system(the community earth system model,CESM),this study comprehensively investigates potential predictability for ENSO across different phases and intensities.The findings reveal that La Niña events possess higher potential predictability relative to their El Niño counterparts.Strong events exhibit significantly higher potential predictability than weak events within the same phase.The potential predictability of distinct ENSO types is primarily influenced by the seasonal variation inherent to their predictability.Regardless of the event classification,the potential predictability is characterized by a rapid decline from spring onwards,with the apex of this decline occurring in summer.The intensity of the seasonal predictability barrier inversely correlates with the upper limit of potential predictability.Specifically,a weaker(stronger)seasonal barrier is associated with a higher(lower)potential predictability.In addition,there is significant interdecadal variability both in the predictability of warm and cold ENSO events.The potential predictability for La Niña events decreases more slowly with increasing lead months,particularly in recent decades,resulting in an overall higher upper limit of potential predictability for La Niña events than for El Niño events over the past century.Nevertheless,El Niño events have also maintained a high potential predictability.This suggests substantial potential for improvement in future prediction for both.展开更多
Suitable temperature and light intensity play important roles in the formation of harmful algae blooms(HABs),which can pose serious threats to aquatic ecosystems and human health.In this study,we measured the growth,p...Suitable temperature and light intensity play important roles in the formation of harmful algae blooms(HABs),which can pose serious threats to aquatic ecosystems and human health.In this study,we measured the growth,physiological function,and paralytic shellfish toxins(PSTs)production of Alexandrium pacificum(CCMA-272),a strain isolated from East China Sea,at different temperatures(15,20,and 25℃)and light intensities(30,60,and 90μmol photons/(m^(2)·s)).Results indicate that temperature and light intensity significantly affected the growth,physiology,and toxigenic potentials of A.pacificum.The optimal conditions for the growth of A.pacificum were observed at 20℃ under60μmol photons/(m^(2)·s).Regarding the production of PSTs,this strain of A.pacificum produced 12 PSTs,including carbamate toxins:saxitoxin(STX),neosaxitoxin(NEO),and gonyautoxin 1–4(GTX1,GTX2,GTX3,GTX4);dicarbamoyl toxins:dicarbamoylsaxitoxin(dcSTX),dicarbamoylgonyautoxin 2,3(dcGTX2,dcGTX3);and N-sulfocarbamoyl toxins:N-sulfocarbamoylgonyautoxin 1,2(C1,C2),and gonyautoxin 5(GTX5).Among all the PSTs,C2 was the most abundant.Low temperature(15℃)and high light intensity(90μmol photons/(m^(2)·s))were beneficial for the production of PSTs in A.pacificum.When cultured at 20 and 25℃,A.pacificum generated comparable total quantities of PSTs,yet the toxicity levels were lower at 25℃.Intra-cellular PSTs contents were greater than extra-cellular PSTs contents,except those under the condition of 25℃ with 30μmol photons/(m^(2)·s).However,as the increase of temperature,A.pacificum released more amounts of analogues with higher toxicity levels(e.g.,STX and dcGTX_(2))into the environment than intracellularly.These findings emphasize the significant sensitivity of A.pacificum to temperature and light intensity,highlighting the importance of evaluating both intra-cellular and extra-cellular PSTs for assessing its toxicity and aiding in the prediction and management of HABs.展开更多
The heat transfer coefficient of the water surface is an important parameter in the design of thermal discharge in nuclear power plant engineering.In this study,in situ observations were performed in the northwestern ...The heat transfer coefficient of the water surface is an important parameter in the design of thermal discharge in nuclear power plant engineering.In this study,in situ observations were performed in the northwestern South China Sea near a coastal nuclear power plant to evaluate the applicability of heat transfer coefficient calculation algorithms commonly used in marine thermal discharge engineering in China.The results show that the Regulation for Hydraulic and Thermal Model in Cooling Water Projects(SL 160-2012)is not applicable in calculating the heat transfer coefficient in offshore areas.SL 160-2012 significantly overestimates the heat loss at the sea surface.However,Code for Design of Cooling for Industrial Recirculating Water(GB/T 50102-2014)performs well,and its estimation coefficient is roughly consistent with the estimations of the COARE 3.6 bulk algorithm,which is extensively used in physical oceanography for calculating air-sea heat fluxes,and the Gunneberg formula.In a 3-day observation,the average heat transfer coefficients estimated using these three algorithms were 50.4,48.5,and 48.8 W m^(-2)℃^(-1),respectively,with a deviation of less than 4% among them,whereas that estimated using SL 160-2012 was as high as 176.3 W m^(-2)℃^(-1).The abnormally large value of SL 160-2012 is due to its additional cooling term,which is artificially increased by 100 times because of the incorrect unit conversion used when developing the regulation.If this error is corrected,the value will decrease to 50.5 W m^(-2)℃^(-1),which is very close to the estimation of GB/T 50102-2014.展开更多
Significant wave period is an important parameter in coastal and offshore engineering design.Traditional spectral wave models do not directly calculate this parameter,which means that it needs to be estimated from the...Significant wave period is an important parameter in coastal and offshore engineering design.Traditional spectral wave models do not directly calculate this parameter,which means that it needs to be estimated from the spectral periods using empirical formulas.The wave energy period is one of the wave periods directly output by many wave models and is often used in studies of wave energy.This study investigated the relationship between significant wave period and wave energy period using wave data measured at three stations in the coastal waters of China.The observations recorded at these stations in the South China Sea,the East China Sea,and the Bohai Sea covered a wide range of surface wave conditions.Analysis indicated that the ratio of significant wave period to wave energy period is closely related to the Goda peakedness parameter of the wave spectra.Therefore,we proposed an empirical formula in which significant wave period is a function of wave energy period and the Goda peakedness parameter.Evaluation results showed that the performance of this formula is substantially better than that of fitting formulas that use constant coefficients.展开更多
Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at...Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at these sites.One such site in the cold seep ecosystem of Krishna-Godavari basin(K-G basin)along the east coast of India,discovered in Feb 2018 at a depth of 1800 m was assessed for its bacterial diversity.The seep bacterial communities were dominated by phylum Proteobacteria(57%),Firmicutes(16%)and unclassified species belonging to the family Helicobacteriaceae.The surface sediments of the seep had maximum OTUs(operational taxonomic units)(2.27×10^(3))with a Shannon alpha diversity index of 8.06.In general,environmental parameters like total organic carbon(p<0.01),sulfate(p<0.001),sulfide(p<0.05)and methane(p<0.01)were responsible for shaping the bacterial community of the cold seep ecosystem in the K-G Basin.Environmental parameters play a significant role in changing the bacterial diversity richness between different cold seep environments in the oceans.展开更多
In this study,the occurrence,sources,and ecological risk of microplastics(>60μm)in the surface and bottom seawater were investigated in the Beibu Gulf,the northern South China Sea.The average abundance of micropla...In this study,the occurrence,sources,and ecological risk of microplastics(>60μm)in the surface and bottom seawater were investigated in the Beibu Gulf,the northern South China Sea.The average abundance of microplastics in surface and bottom waters was 1.35±0.93 and 0.79±0.50 items/m~3,respectively.Microplastics in both surface and bottom waters were predominantly in the form of fragments,and mostly in green.The composition of microplastics in surface water was primarily poly(methyl methacrylate)(PMA),whereas in bottom water,polyethylene(PE)dominated.Positive matrix factorization(PMF)modeling revealed that the primary sources of microplastics were pipeline abrasion,fishing activities,plastic waste,landfill disposal,transportation,aquaculture,and construction activities.The pollution load index(PLI)indicated that the overall risk of microplastic pollution in the Beibu Gulf was low.Conversely,the polymer hazard index(PHI)for microplastics was relatively high.These data underscore the importance of timely and effective reduction of human-intensive activities contributing to microplastic pollution and provide valuable information for further research in microplastic ecotoxicology and biogeochemistry.展开更多
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 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.
基金jointly supported by the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources,Xiamen(No.2018002)the Guangxi Natural Science Fundation(No.2022GXNSFBA035588)+1 种基金the National Natural Science Foundation of China(Nos.41506050,41402193)the Scientific Research Foundation of Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration(No.19-185-17-09)。
文摘The tectonic evolution of Borneo and the affiliation between Southern and Northern Borneo remains unclear.The Rajang and Crocker Fan sediments,as one of the largest ancient submarine fans in Southeast Asia have witnessed the tectonic evolution of Borneo since at least the late Mesozoic.In this study,we present laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)U-Pb dating and Hf isotopic results of detrital zircons from the Trusmadi and Crocker formations within the Crocker Fan of Sabah,Northern Borneo.Our results,coupled with previous data,show that the Crocker Fan sediments in Sabah of Northern Borneo display similar age spectra to the Rajang Fan sediments in Sarawak of Central Borneo,with two major age clusters at 130-80 and 280-200 Ma.Further provenance analysis based on mineral shape with a prismatic characteristic and similar detrital zircon Hf isotopes of the two formations illustrates that the Jurassic-Cretaceous and partly Triassic detrital zircons of the Crocker and Rajang Fan sediments were derived from the erosion of contemporaneous magmatic rocks;part of Permian-Triassic ones could be the recycling of the Jurassic deposits in SW Borneo.The initial provenance of these Permian-Triassic detritus could be synchronous magmatic rocks in the Tin belt of the Malay Peninsula.Combining with previous data,we propose that the entire Borneo continent,including both Southern and Northern Borneo,developed a common Mesozoic continental magmatic arc.Moreover,we postulate that the Rajang and Crocker fans formed in a fore-arc extensional rift basin related to the retreat of the subducted Paleo-Pacific Plate beneath the Northern Borneo margin.
基金The National Natural Science Foundation of China under contract No.41906193the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources,under contract No.2019033+2 种基金the Natural Science Foundation of Fujian Province under contract No.2019J05147the Federal Ministry of Education and Research of Germany under contract No.FKZ 03F03F0783Athe National Polar Special Program under contract Nos IRASCC 01-01-02 and IRASCC 02-02.
文摘The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved N_(2)O from large regions such as the Southern Ocean.To address this deficit,N_(2)O was measured in the Prydz Bay in February 2015 during the 31st Chinese National Antarctic Research Expedition.N_(2)O concentrations(saturation)in the surface layer were generally low(undersaturation with respect to atmospheric equilibrium)and ranged from 13.3 nmol/L to 16.1 nmol/L(83%–102%)at the time of sampling.A comparison of our observations with archived data revealed that no discernible trend in N_(2)O concentrations in the surface waters of Prydz Bay could be detected for the period between 2006 and 2015.Temperature and salinity changes driven by meltwater input were the predominant controls on N_(2)O concentrations in surface waters.At depth,the distribution of N_(2)O concentrations was dominated by production via nitrification in offshore deep waters and vertical convection in the shelf waters,where concentrations were lower and gradients were less steep.Our results suggest a rather unusual pattern of N_(2)O distribution in the Prydz Bay(low N_(2)O in shelf waters compared with the open ocean),providing important insights into the coastal dynamics of N_(2)O in high-latitude polar regions.
基金The National Key Research and Development Program of China under contact No.2021YFF0501304the Natural Science Foundation of Xiamen,China under contact No.3502Z20227244the Scientific Research Foundation of the Third Institute of Oceanography,MNR under contact Nos 2019021 and 2022009.
文摘Low iron content is a peculiar feature of marine ecosystems,where microbes have to produce iron-chelating molecules such as siderophores to survive.Very little is known about siderophore-producing bacteria in the oceans.In this study,we screened 1546 strains from marine seawater and sediments,which were deposited in the Marine Culture Collection of China(MCCC),and further analyzed the diversity of positive strains and their potential genes related to iron acquisition.Of the 1546 isolates,856 strains(55.37%)showed positive siderophore-producing activity on the Chrome Azurol Sulfonate(CAS)plates.Among these,isolates from seawater environments had a higher positive proportion(535).Some genera showed a higher proportion(>70%)of positive siderophore producers,such as Alteromonas(89/112),Marinobacter(78/109),Vibrio(21/27),Shewanella(7/8)in the Gammaproteobacteria,Sulfitobacter(17/21),Martelella(5/6)in the Alphaproteobacteria,and Joostella(6/7)in the phylum Bacteroidetes.Siderophore biosynthesis genes,including those for vanchrobactin,vibrioferrin,petrobactin,and aerobactin,as well as transport and iron storage proteins,were also identified in the positive bacterial genomes.The study revealed that a variety of bacterial strains demonstrate the production of siderophores,which could significantly contribute to the iron cycle within marine ecosystems,encompassing both seawater and marine sediments.
基金Supported by the National Natural Science Foundation of China(No.41776177)the Qingdao Marine Science and Technology Pilot National Laboratory Fund(Nos.2016ASKJ14,QNLM2016ORP0403)。
文摘Mussels are common anchoring organisms that adhere to the surfaces of various substrates with their byssus.The adhesion of mussel to substrates is contingent upon the presence of mussel foot proteins,of which Mytilus edulis foot protein-1(Mefp-1)has been identified as the most abundant protein.It has been found that lipids are involved in the mussel adhesion process and can facilitate Mefp-1adhesion.In this research,the adhesion behavior of Mefp-1 on various substrate surfaces under the effect of typical seawater cations with or without the presence of lipid were investigated using a quartz crystal microbalance with dissipation(QCM-D).Results indicate that the presence of cations Ca^(2+),Mg^(2+),Na^(+),and K^(+)leads to varying degrees of reduction in the adhesion performance of Mefp-1 on different substrates.The degree of this reduction,however,was much alleviated in the presence of palmitic acid,which is involved in the mussel adhesion process.Therefore,the involvement of palmitic acid is advantageous for mussel protein adhesion to the substrate surface in the marine environment.This study illustrated the significant contribution of palmitic acid to mussel adhesion,which can help to better understand biofouling mechanisms and develop biomimetic adhesive materials.
基金The National Key Research and Development Program of China under contract No.2022YFE0136500the Scientific Research Fund of the Second Institute of Oceanography,Ministry of Natural Resources,under contract Nos JG2212 and JG2211+2 种基金the National Natural Science Foundation of China under contract Nos 42276255,41976228,and 42176227the National Polar Special Program“Impact and Response of Antarctic Seas to Climate Change”under contract Nos IRASCC 01-01-02 and IRASCC 02-02the China Scholarship Council under contract No.201704180017.
文摘The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle,influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean.However,the impact of variability in the timing of seasonal sea ice retreat on the flux and composition of sinking particulate matter remains to be elucidated.In this study,we deployed sediment traps in Prydz Bay during the austral summers of 2019/2020 and 2020/2021,noting that sea ice melting occurred approximately one and a half months earlier in the former summer compared to the latter.We analyzed sediment trap data,which included total mass flux(TMF),particulate organic carbon(POC),biogenic silica(BSi),particulate inorganic carbon,and lithogenic particle(Litho)fluxes,as well as the stable isotopesδ^(13)C andδ^(15)N of particulate organic matter(POM).Additionally,we incorporated remote sensing data on sea ice concentration and chlorophyll a.This dramatic delay in sea ice melting timing could result in a significant increase in TMF,BSi and POC fluxes in the summer of 2020/2021 compared to 2019/2020.Elevated BSi fluxes and more ^(13)C-depleted POC in the austral summer of 2020/2021 suggest that the delayed melting of sea ice may have stimulated the productivity of centric diatoms.Furthermore,the higher BSi/POC ratio and more negativeδ^(15)N values of POM,along with a reduced presence of krill in the traps,indicate a diminished grazing pressure from zooplankton,which collectively enhanced the sedimentation efficiency of POC during the austral summer of 2020/2021.These findings highlight the critical role of sea ice melting timing in regulating productivity,flux and composition of sinking particulate matter in the Prydz Bay ecosystem,with significant implications for carbon cycling in polar oceans.
基金The fund from Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract No.SML2021SP310the National Natural Science Foundation of China under contract Nos 42227901 and 42475061the Key R&D Program of Zhejiang Province under contract No.2024C03257.
文摘The inherent asymmetry and diversity of the El Niño-Southern Oscillation(ENSO)pose substantial challenges to its prediction.Potential predictability measures the upper limit of predictability for a certain event.Assessing the potential predictability of ENSO across varying phases and intensities with sophisticated climate models is crucial for understanding the upper limits of forecasting capabilities and identifying room for future enhancement.Based on the hindcast dataset with a recently developed ensemble forecasting system(the community earth system model,CESM),this study comprehensively investigates potential predictability for ENSO across different phases and intensities.The findings reveal that La Niña events possess higher potential predictability relative to their El Niño counterparts.Strong events exhibit significantly higher potential predictability than weak events within the same phase.The potential predictability of distinct ENSO types is primarily influenced by the seasonal variation inherent to their predictability.Regardless of the event classification,the potential predictability is characterized by a rapid decline from spring onwards,with the apex of this decline occurring in summer.The intensity of the seasonal predictability barrier inversely correlates with the upper limit of potential predictability.Specifically,a weaker(stronger)seasonal barrier is associated with a higher(lower)potential predictability.In addition,there is significant interdecadal variability both in the predictability of warm and cold ENSO events.The potential predictability for La Niña events decreases more slowly with increasing lead months,particularly in recent decades,resulting in an overall higher upper limit of potential predictability for La Niña events than for El Niño events over the past century.Nevertheless,El Niño events have also maintained a high potential predictability.This suggests substantial potential for improvement in future prediction for both.
基金Supported by the National Natural Science Foundation of China(Nos.32101290,52009082)the Natural Science Foundation of Jiangsu Province(No.BK20210364)the Fundamental Research Funds for the Central Universities(No.B220202044)。
文摘Suitable temperature and light intensity play important roles in the formation of harmful algae blooms(HABs),which can pose serious threats to aquatic ecosystems and human health.In this study,we measured the growth,physiological function,and paralytic shellfish toxins(PSTs)production of Alexandrium pacificum(CCMA-272),a strain isolated from East China Sea,at different temperatures(15,20,and 25℃)and light intensities(30,60,and 90μmol photons/(m^(2)·s)).Results indicate that temperature and light intensity significantly affected the growth,physiology,and toxigenic potentials of A.pacificum.The optimal conditions for the growth of A.pacificum were observed at 20℃ under60μmol photons/(m^(2)·s).Regarding the production of PSTs,this strain of A.pacificum produced 12 PSTs,including carbamate toxins:saxitoxin(STX),neosaxitoxin(NEO),and gonyautoxin 1–4(GTX1,GTX2,GTX3,GTX4);dicarbamoyl toxins:dicarbamoylsaxitoxin(dcSTX),dicarbamoylgonyautoxin 2,3(dcGTX2,dcGTX3);and N-sulfocarbamoyl toxins:N-sulfocarbamoylgonyautoxin 1,2(C1,C2),and gonyautoxin 5(GTX5).Among all the PSTs,C2 was the most abundant.Low temperature(15℃)and high light intensity(90μmol photons/(m^(2)·s))were beneficial for the production of PSTs in A.pacificum.When cultured at 20 and 25℃,A.pacificum generated comparable total quantities of PSTs,yet the toxicity levels were lower at 25℃.Intra-cellular PSTs contents were greater than extra-cellular PSTs contents,except those under the condition of 25℃ with 30μmol photons/(m^(2)·s).However,as the increase of temperature,A.pacificum released more amounts of analogues with higher toxicity levels(e.g.,STX and dcGTX_(2))into the environment than intracellularly.These findings emphasize the significant sensitivity of A.pacificum to temperature and light intensity,highlighting the importance of evaluating both intra-cellular and extra-cellular PSTs for assessing its toxicity and aiding in the prediction and management of HABs.
基金supported by the Laoshan Laboratory(No.LSKJ202201600)the National Natural Science Foundation of China(No.41821004)。
文摘The heat transfer coefficient of the water surface is an important parameter in the design of thermal discharge in nuclear power plant engineering.In this study,in situ observations were performed in the northwestern South China Sea near a coastal nuclear power plant to evaluate the applicability of heat transfer coefficient calculation algorithms commonly used in marine thermal discharge engineering in China.The results show that the Regulation for Hydraulic and Thermal Model in Cooling Water Projects(SL 160-2012)is not applicable in calculating the heat transfer coefficient in offshore areas.SL 160-2012 significantly overestimates the heat loss at the sea surface.However,Code for Design of Cooling for Industrial Recirculating Water(GB/T 50102-2014)performs well,and its estimation coefficient is roughly consistent with the estimations of the COARE 3.6 bulk algorithm,which is extensively used in physical oceanography for calculating air-sea heat fluxes,and the Gunneberg formula.In a 3-day observation,the average heat transfer coefficients estimated using these three algorithms were 50.4,48.5,and 48.8 W m^(-2)℃^(-1),respectively,with a deviation of less than 4% among them,whereas that estimated using SL 160-2012 was as high as 176.3 W m^(-2)℃^(-1).The abnormally large value of SL 160-2012 is due to its additional cooling term,which is artificially increased by 100 times because of the incorrect unit conversion used when developing the regulation.If this error is corrected,the value will decrease to 50.5 W m^(-2)℃^(-1),which is very close to the estimation of GB/T 50102-2014.
基金The National Natural Science Foundation of China under contract No.41821004the Basic Scientific Fund for National Public Research Institutes of China under contract No.2020Q08the Fund of Laoshan Laboratory under contract No.LSKJ202201600.
文摘Significant wave period is an important parameter in coastal and offshore engineering design.Traditional spectral wave models do not directly calculate this parameter,which means that it needs to be estimated from the spectral periods using empirical formulas.The wave energy period is one of the wave periods directly output by many wave models and is often used in studies of wave energy.This study investigated the relationship between significant wave period and wave energy period using wave data measured at three stations in the coastal waters of China.The observations recorded at these stations in the South China Sea,the East China Sea,and the Bohai Sea covered a wide range of surface wave conditions.Analysis indicated that the ratio of significant wave period to wave energy period is closely related to the Goda peakedness parameter of the wave spectra.Therefore,we proposed an empirical formula in which significant wave period is a function of wave energy period and the Goda peakedness parameter.Evaluation results showed that the performance of this formula is substantially better than that of fitting formulas that use constant coefficients.
文摘Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at these sites.One such site in the cold seep ecosystem of Krishna-Godavari basin(K-G basin)along the east coast of India,discovered in Feb 2018 at a depth of 1800 m was assessed for its bacterial diversity.The seep bacterial communities were dominated by phylum Proteobacteria(57%),Firmicutes(16%)and unclassified species belonging to the family Helicobacteriaceae.The surface sediments of the seep had maximum OTUs(operational taxonomic units)(2.27×10^(3))with a Shannon alpha diversity index of 8.06.In general,environmental parameters like total organic carbon(p<0.01),sulfate(p<0.001),sulfide(p<0.05)and methane(p<0.01)were responsible for shaping the bacterial community of the cold seep ecosystem in the K-G Basin.Environmental parameters play a significant role in changing the bacterial diversity richness between different cold seep environments in the oceans.
基金Supported by the National Natural Science Foundation of China(No.U20A20103)the Scientific Research Fund of the Fourth Institute of Oceanography+1 种基金Guangxi Funding Project(No.304024XM20N0006)the Guangxi Talent Science and Technology Project(No.2019AC17008)。
文摘In this study,the occurrence,sources,and ecological risk of microplastics(>60μm)in the surface and bottom seawater were investigated in the Beibu Gulf,the northern South China Sea.The average abundance of microplastics in surface and bottom waters was 1.35±0.93 and 0.79±0.50 items/m~3,respectively.Microplastics in both surface and bottom waters were predominantly in the form of fragments,and mostly in green.The composition of microplastics in surface water was primarily poly(methyl methacrylate)(PMA),whereas in bottom water,polyethylene(PE)dominated.Positive matrix factorization(PMF)modeling revealed that the primary sources of microplastics were pipeline abrasion,fishing activities,plastic waste,landfill disposal,transportation,aquaculture,and construction activities.The pollution load index(PLI)indicated that the overall risk of microplastic pollution in the Beibu Gulf was low.Conversely,the polymer hazard index(PHI)for microplastics was relatively high.These data underscore the importance of timely and effective reduction of human-intensive activities contributing to microplastic pollution and provide valuable information for further research in microplastic ecotoxicology and biogeochemistry.
