The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectrometry and X-ray Diffract...The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectrometry and X-ray Diffraction.The exposure corrosion experiment of these magnesium alloys was tested in South China Sea and KEXUE vessel atmospheric environment.The corrosion characteristic and mechanism of magnesium alloys of Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were analyzed by weight loss rate,corrosion depth,corrosion products and corrosion morphologies.The electrochemical corrosion tests were also measured in the natural seawater.The comprehensive results showed that Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy existed the best corrosion resistance whether in the marine atmospheric environment and natural seawater environment.That depended on the microstructure,type and distribution of precipitated phases in Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy.Sufficient quantity anodic precipitated phases in the microstructure of Mg-5Y-1.5Nd-4Zn-0.5Zr alloy played the key role in the corrosion resistance.展开更多
Planktonic foraminifer Globigerinoides ruber(white)and Trilobatus sacculifer are the most frequently used mixedlayer dwelling species for reconstructing past oceanic environments.Specifically,the Mg/Ca ratios of these...Planktonic foraminifer Globigerinoides ruber(white)and Trilobatus sacculifer are the most frequently used mixedlayer dwelling species for reconstructing past oceanic environments.Specifically,the Mg/Ca ratios of these two foraminiferal species have been used for reconstructing tropical/subtropical changes in sea surface temperature(SST).However,these two species have different morphotypes,of which the spatial and temporal differences in Mg/Ca ratios and their influencing factors are still unclear.Our objective is to investigate the potential differences between the Mg/Ca ratios of these different morphotypes of G.ruber(white)and T.sacculifer in the western Philippine Sea(WPS)and determine their implications for the reconstruction of SST and upper-ocean structure.Mg/Ca measurements are made on two basic morphotypes of G.ruber(white)[sensu stricto(s.s.)and sensu lato(s.l.)]and T.sacculifer[with(w)and without(w/o)a sac-like final chamber]on samples of Site MD06-3047B from the WPS.Our results reveal that Mg/Ca ratios of different G.ruber morphotypes show consistent differences;and those of T.sacculifer morphotypes show staged variations since MIS 3.It is suggested to select a single morphotype for reconstructing SST changes using the Mg/Ca ratios of G.ruber and T.sacculifer in the WPS.Furthermore,the Mg/Ca ratios between G.ruber s.s.and G.ruber s.l.[Δ(Mg/Ca)_(G.ruber s.s.-s.l.)]downcore MD06-3047B covaries with indexes of summer monsoon.Combining with the core-top results,showing regional variation of differences in theΔ(Mg/Ca)_(G.ruber s.s.-s.l.)over the western tropical Pacific,we propose thatΔ(Mg/Ca)_(G.ruber s.s.-s.l.)may tend to reflect summer mixed layer depth.展开更多
The Yellow Sea Cold Water Mass(YSCWM)is a distinct hydrographic phenomenon of the Yellow Sea,and the distribution pattern of meio-and macrobenthos diff ers inside and outside of the YSCWM.However,such a pattern has ne...The Yellow Sea Cold Water Mass(YSCWM)is a distinct hydrographic phenomenon of the Yellow Sea,and the distribution pattern of meio-and macrobenthos diff ers inside and outside of the YSCWM.However,such a pattern has never been observed in the microbenthic ciliate communities.Therefore,we hypothesized that benthic ciliates followed a similar distribution pattern as meio-and macrobenthos,but this pattern has not been uncovered by morphological methods.We evaluated the diversity and distribution of benthic ciliates at fi ve stations along hydrographic gradients across the YSCWM and adjacent shallow water by using morphology and DNA and complementary DNA(cDNA)high-throughput sequencing of the V4 region of 18S rRNA gene.Results showed that the diversity of benthic ciliates detected by DNA(303 OTUs),and the cDNA(611 OTUs)sequencing was much higher than that detected by the morphological method(79 species).Morphological method detected roughly diff erent ciliate communities inside and outside of the YSCWM,but without statistical signifi cance.No clear pattern was obtained by DNA sequencing.In contrast,cDNA sequencing revealed a distinct distribution pattern of benthic ciliate communities like meioand macrobenthos,which coincided well with the results of the environmental parameter analysis.More than half of the total sequences detected by DNA sequencing belonged to planktonic ciliates,most(if not all)of which were recovered from historic DNA originating through the sedimentation of pelagic forms because none of them were observed morphologically.The irrelevant historic DNA greatly infl uenced the recovery of rare species and thus limited the understanding of the benthic ciliate diversity and distribution.Our research indicates that the methods used have signifi cant eff ects on the investigation of benthic ciliate communities and highlights that cDNA sequencing has great advantages in estimating the diversity and distribution of benthic ciliates,as well as the potential for benthic environmental assessments.展开更多
This paper examines the simplification strategy of retaining only the nonhydrostatic effect of local acceleration in a three-dimensional fully nonhydrostatic model regarding the submesoscale wave phenomenon in the oce...This paper examines the simplification strategy of retaining only the nonhydrostatic effect of local acceleration in a three-dimensional fully nonhydrostatic model regarding the submesoscale wave phenomenon in the ocean.Elaborate scale analysis of the vertical component of the Reynold-averaged Navier-Stokes(RANS)equation was performed,confirming the rationalization of this simplification.Then,the simplification was implemented in a RANS equation-based nonhydrostatic model NHWAVE(nonhydrostatic WAVE)to make a simplified nonhydrostatic model.Numerical examples were taken to test its performance,including surface sinusoidal waves propagating on an idealized East China Sea topography,tidally induced internal lee waves and small-scale solitary waves.The results show that in a considerably wide range of nonlinear strengths,the simplified nonhydrostatic model can obtain similar results as those in the fully nonhydrostatic model,even for smaller-scale solitary waves.Nonlinearity influences the applicability of the simplification.The stronger the nonlinearity is,the worse the simplified model describes the nonhydrostatic phenomenon.In general,the simplified nonhydrostatic model can simulate surface waves better than internal waves.Improvement of computational efficiency in the simplified nonhydrostatic model is reasonable,reducing the central processing unit time duration in the fully nonhydrostatic model by 16.4%–20.6%.The specially designed algorithm based on the simplified nonhydrostatic equation can remarkably reduce the computational time.展开更多
To investigate the nature of gas hydrates in the Makran area,new high-resolution geophysical data were acquired between 2018-2019.The data collected comprise multibeam and two-dimensional multi-channel seismic reflect...To investigate the nature of gas hydrates in the Makran area,new high-resolution geophysical data were acquired between 2018-2019.The data collected comprise multibeam and two-dimensional multi-channel seismic reflection data.The multibeam bathymetry data show East-North-East(ENE)ridges,piggy-back basins,canyon and channel systems,and the morphology of the abyssal plain.Continuous and discontinuous bottom simulating reflectors(BSRs)occur in the piggy-back basins on most of the seismic profiles available.The BSRs cut the dipping layers with strong amplitude and reversed polarity.Discontinuous BSRs indicate a transition along a dipping high-permeable sand layers from gas-rich segment to the gas hydrate-bearing segment and sugge st alternating sediments of fine and relatively coarse grain size.Double BSRs are highly dynamic and attributed to slumps occurring in the study area.The BSRs induced by slumps are located both at deep and shallow depths,responding to the temperature or pressure variation.For the first time,BSRs are observed in the abyssal plain of the Makran area,being associated with anticline structures,which do not show large spatial continuity and are strongly conditioned by structural conditions such as anticlines and fluid migration pathways,including deep fault,gas chimney,and high-permeable sedimentary layer.Our results may help to assess the gas hydrate potential within the piggy-back basins and to determine the most promising target areas.Moreover,results about the abyssal plain BSR may help to locate hydrocarbon reservoirs in the deep ocean.展开更多
Finite-difference(FD)method is the most extensively employed numerical modeling technique.Nevertheless,when using the FD method to simulate the seismic wave propagation,the large spatial or temporal sampling interval ...Finite-difference(FD)method is the most extensively employed numerical modeling technique.Nevertheless,when using the FD method to simulate the seismic wave propagation,the large spatial or temporal sampling interval can lead to dispersion errors and numerical instability.In the FD scheme,the key factor in determining both dispersion errors and stability is the selection of the FD weights.Thus,How to obtain appropriate FD weights to guarantee a stable numerical modeling process with minimum dispersion error is critical.The FD weights computation strategies can be classified into three types based on different computational ideologies,window function strategy,optimization strategy,and Taylor expansion strategy.In this paper,we provide a comprehensive overview of these three strategies by presenting their fundamental theories.We conduct a set of comparative analyses of their strengths and weaknesses through various analysis tests and numerical modelings.According to these comparisons,we provide two potential research directions of this field:Firstly,the development of a computational strategy for FD weights that enhances stability;Secondly,obtaining FD weights that exhibit a wide bandwidth while minimizing dispersion errors.展开更多
Seismic prediction of cracks is of great significance in many disciplines,for which the rock physics model is indispensable.However,up to now,multitudinous analytical models focus primarily on the cracked rock with th...Seismic prediction of cracks is of great significance in many disciplines,for which the rock physics model is indispensable.However,up to now,multitudinous analytical models focus primarily on the cracked rock with the isotropic background,while the explicit model for the cracked rock with the anisotropic background is rarely investigated in spite of such case being often encountered in the earth.Hence,we first studied dependences of the crack opening displacement tensors on the crack dip angle in the coordinate systems formed by symmetry planes of the crack and the background anisotropy,respectively,by forty groups of numerical experiments.Based on the conclusion from the experiments,the analytical solution was derived for the effective elastic properties of the rock with the inclined penny-shaped cracks in the transversely isotropic background.Further,we comprehensively analyzed,according to the developed model,effects of the crack dip angle,background anisotropy,filling fluid and crack density on the effective elastic properties of the cracked rock.The analysis results indicate that the dip angle and background anisotropy can significantly either enhance or weaken the anisotropy degrees of the P-and SH-wave velocities,whereas they have relatively small effects on the SV-wave velocity anisotropy.Moreover,the filling fluid can increase the stiffness coefficients related to the compressional modulus by reducing crack compliance parameters,while its effects on shear coefficients depend on the crack dip angle.The increasing crack density reduces velocities of the dry rock,and decreasing rates of the velocities are affected by the crack dip angle.By comparing with exact numerical results and experimental data,it was demonstrated that the proposed model can achieve high-precision estimations of stiffness coefficients.Moreover,the assumption of the weakly anisotropic background results in the consistency between the proposed model and Hudson's published theory for the orthorhombic rock.展开更多
The resource of Fenneropenaeus chinensis has declined sharply due to excessive fishing intensity,ecological changes and diseases.In order to supplement the fishing yield and restore resources of F.chinensis,the releva...The resource of Fenneropenaeus chinensis has declined sharply due to excessive fishing intensity,ecological changes and diseases.In order to supplement the fishing yield and restore resources of F.chinensis,the relevant authorities have carried out the activities of stock enhancement and releasing.It can increase biomass and recover resources.However,compared with increasing biomass,there were still few reports on its effect on the recovery of resources.Resource recovery is a process related to whether the released individuals can form a reproductive population.Up to now,there has been a lack of evidence whether the released F.chinensis can complete the entire life history,and form reproduction population.In this study,gravid female shrimp after spawning migration were captured from coastal waters of Haiyang,Qingdao,and Yellow Sea.After identifying parentage relationships using simple sequence repeat(SSR)and mtDNA haplotype,it was finally confirmed that there were eight released individuals in the recapture samples.It was confirmed for the first time that at least part of the released F.chinensis can complete overwintering and reproductive migration,and maintain the migration habits as their wild counterparts.Therefore,we infered that the released shrimp can reproduce under natural conditions,these F.chinensis can form reproductive populations theoretically if without human intervention.These results indicated that enhancenment and release activities have a positive effect on resource recovery.展开更多
A novel and reactive oxygen species(ROS)responsive astaxanthin phenylboronic acid derivative(AstaDPBA)was constructed by grafting phenylboronic acid(PBA)onto astaxanthin succinate diester(AstaD),and its chemical struc...A novel and reactive oxygen species(ROS)responsive astaxanthin phenylboronic acid derivative(AstaDPBA)was constructed by grafting phenylboronic acid(PBA)onto astaxanthin succinate diester(AstaD),and its chemical structure and physicochemical property were identified.AstaD-PBA could effectively improve the ROS quenching ability in the lipopolysaccharide(LPS)-induced RAW264.7 cell inflammation model.Then,the bioactivity of AstaD-PBA was studied by 4 zebrafish ROS-responsive infl ammatory models induced by LPS,copper(Cu^(2+)),high-fat diet,and dextran sodium sulfate(DSS).The results suggest that AstaD-PBA might have high biosafety and the best effect on ulcerative colitis(UC)induced by DSS.Furtherly,AstaDPBA significantly alleviated and treated weight loss and colonic shrinkage,inhibited infl ammatory cytokines,and maintained microbiota homeostasis to improve UC in C57BL/6J mice.Alistipes and Oscillibacter were expected to be considered UC marker fl ora according to the Metastats analysis and Pearson correlation Mantel test(P<0.01)of 16S rRNA gene sequencing data.In conclusion,AstaD-PBA has been promised to be a functional compound to improve UC and maintain intestinal microbiota homeostasis.展开更多
Trimethylamine N-oxide(TMAO)is a risk factor of various chronic diseases,which was produced by metabolism from precursors to trimethylamine(TMA)in gut and the oxidation from TMA in liver.The TMA generation was influen...Trimethylamine N-oxide(TMAO)is a risk factor of various chronic diseases,which was produced by metabolism from precursors to trimethylamine(TMA)in gut and the oxidation from TMA in liver.The TMA generation was influenced by diet,mainly due to the rich TMAO precursors in diet.However,it was still unclear that the effects of different proportion and source of macronutrients in different dietary pattern on the production process of TMAO.Here,the generation of TMA from precursors and TMAO from TMA was determined after single oral choline chloride and intraperitoneal injection TMA,respectively,in mice fed with carbohydrates,proteins and fats in different proportion and sources.The results suggested that the generation of TMAO was increased by low non-meat protein and high fat via enhancing the production of TMAO from TMA,and decreased by plant protein and refined sugar via reducing TMA production from precursors in gut and TMAO transformation from TMA in liver.The high fat and high sugar diets accelerating the development of atherosclerosis did not increase the production of TMAO,the risk factor for atherosclerosis,which indicated that the dietary compositions rather than the elevated TMAO level might be a more key risk factor for atherosclerosis.展开更多
The coupling between wind stress perturbations and sea surface temperature(SST)perturbations induced by tropical instability waves(TIWs)in the Pacific Ocean has been revealed previously and proven crucial to both the ...The coupling between wind stress perturbations and sea surface temperature(SST)perturbations induced by tropical instability waves(TIWs)in the Pacific Ocean has been revealed previously and proven crucial to both the atmosphere and ocean.However,an overlooked fact by previous studies is that the loosely defined“TIWs”actually consist of two modes,including the Yanai wave-based TIW on the equator(hereafter eTIW)and the Rossby wave-based TIW off the equator(hereafter vTIW).Hence,the individual feedbacks of the wind stress to the bimodal TIWs remain unexplored.In this study,individual coupling relationships are established for both eTIW and v TIW,including the relationship between the TIW-induced SST perturbations and two components of wind stress perturbations,and the relationship between the TIW-induced wind stress perturbation divergence(curl)and the downwind(crosswind)TIW-induced SST gradients.Results show that,due to different distributions of eTIW and vTIW,the coupling strength induced by the eTIW is stronger on the equator,and that by the vTIW is stronger off the equator.The results of any of eTIW and vTIW are higher than those of the loosely defined TIWs.We further investigated how well the coupling relationships remained in several widely recognized oceanic general circulation models and fully coupled climate models.However,the coupling relationships cannot be well represented in most numerical models.Finally,we confirmed that higher resolution usually corresponds to more accurate simulation.Therefore,the coupling models established in this study are complementary to previous research and can be used to refine the oceanic and coupled climate models.展开更多
Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.n...Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.nozakii medusae on different prey items.Research is also lacking on the intraguild predation of Aurelia coerulea(another common bloom jellyfish in offshore China)by C.nozakii.To address the knowledge gaps,the clearance rates of C.nozakii for different prey items,including copepods(small<1000μm and large>1000μm),fish larvae,and gelatinous prey(hydromedusae,A.coerulea ephyrae,and chaetognaths),were measured.The influence of predator size on the clearance rate was also determined.Additionally,we examined the intraguild predation of C.nozakii on A.coerulea medusae.The clearance rates of C.nozakii varied widely with prey organisms,being independent of prey concentrations.Gelatinous organisms,except for chaetognaths,were captured with considerably high efficiency,followed by fish larvae and copepods,indicating the preferential prey selection of gelatinous organisms by C.nozakii.The clearance rate increased linearly with the cross-sectional area of C.nozakii.Body size in medusae may,to some extents,underpin their capacity to capture more prey by increasing the encounter rate and capture success through ontogeny.C.nozakii preyed voraciously on A.coerulea in high feeding efficiency,but the clearance rate decreased with increasing A.coerulea(as prey)size.This phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of A.coerulea by C.nozakii.The information regarding the feeding ecology of C.nozakii reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.展开更多
Sea cucumber saponins have attracted more attention in recent years due to biological activities.It is a popular practice to soak sea cucumber in Baijiu at home and being applied to industrial manufacturing in China.H...Sea cucumber saponins have attracted more attention in recent years due to biological activities.It is a popular practice to soak sea cucumber in Baijiu at home and being applied to industrial manufacturing in China.However,knowledge of the effect of alcohol on the absorption and metabolism of sea cucumber saponins is limited.The effects of alcohol on digestion,absorption and metabolism of sea cucumber saponins in BALB/c mice were investigated after gavage and tail intravenous injection.The results showed that the content of saponins in serum and liver was significantly higher under the influence of alcohol than that in the control group after oral administration.Alcohol promoted the absorption of sea cucumber saponins prototype as well as inhibited the process of saponins being transformed into deglycositic metabolites in the small intestine.Moreover,sea cucumber saponins remained in circulation for a long time and alcohol slowed down the clearance of sea cucumber saponins under the influence of alcohol after intravenous injection.This confirmed the feasibility of marinating sea cucumber in Baijiu to improve the efficacy of saponins and provides an important theoretical basis for the utilization of sea cucumber and the development of sea cucumber liquor.展开更多
The basic structure and intraseasonal evolution of currents in the southeastern Andaman Sea was analyzed based on data collected in 2017 from two subsurface moorings(C1 and C5).Periodic variation in the upper ocean cu...The basic structure and intraseasonal evolution of currents in the southeastern Andaman Sea was analyzed based on data collected in 2017 from two subsurface moorings(C1 and C5).Periodic variation in the upper ocean currents of the Andaman Sea was investigated by combining observational and satellite data.Mooring observations show that rapid changes of current speed and direction occurred in May and June,with a significant increase in current velocity at the C1 mooring.In the second half of the year,southward flow dominated at the C1 mooring,and alternating northward and southward flows were evident at the C5 mooring during the same period but the northward flow prevailed in boreal winter.In addition,analysis of the power spectra of the upper currents revealed that the tidal period at both moorings is primarily semidiurnal with weaker energy than that of the low-frequency currents.The upper ocean currents at the C1 and C5 moorings exhibited intraseasonal variation of 30-60 d and 120 d,while the zonal current at the C1 mooring exhibited a notable period of approximately 180 d.Further analysis indicated that the variability of currents in the Andaman Sea is influenced primarily by equatorial Kelvin waves and Rossby wave packets.Moreover,our results suggest that equatorial Kelvin waves from the eastern Indian Ocean entered the Andaman Sea in the form of Wyrtki Jets and propagated primarily along two distinct pathways during the observation period.In addition to coastal boundary Kelvin waves,it was found that a branch of the Wyrtki Jet that directly enters the Andaman Sea and flows northward along the slope of the continental shelf,and reflected Rossby wave packets by topography.展开更多
Lipophilic marine toxins(LMTs)produced by some microalgae in the sea could accumulate in shellfish and pose potential threats to the health of seafood consumers.Phytoplankton and shellfish samples were collected from ...Lipophilic marine toxins(LMTs)produced by some microalgae in the sea could accumulate in shellfish and pose potential threats to the health of seafood consumers.Phytoplankton and shellfish samples were collected from coastal waters of Weihai in Shandong Peninsula,China in autumn,2020,and screened for lipophilic marine toxins and their potential producers using liquid chromatography-tandem mass spectrometry(LC-MS/MS)analysis and high throughput sequencing of partial DNA(V4 region of the 18S rRNA gene)extracted from phytoplankton.Pectenotoxin-2(PTX2),trace amounts of azaspiracid(AZA1 or AZA40),and 13-desmethyl spirolide C(13-DesMe-C)were detected in phytoplankton samples,while PTX2 and gymnodimine(GYM)were detected in shellfish samples.The toxin content in shellfish samples was much lower than the regulatory limit or values reported previously.Results suggest that lipophilic marine toxins should have low risk in coastal waters of Weihai in autumn.Based on the data of high throughput sequencing,the OTUs were assigned to 5 identified species of Alexandrium,including A.ostenfeldii capable of producing 13-DesMe-C and GYM.Two OTUs were found closely related to the toxic species in genus Dinophysis,but it is impossible to assign them to any identified species due to the low resolving power of the V4 region for Dinophysis.The OTUs could not be assigned to any identified species in the genus Azadinium,suggesting the existence of unidentified species in this region.展开更多
The diversity and distribution of Hippodonta species on the coast of China are largely unknown due to limited investigations.In this paper,we report the detailed morphology and ultrastructure of two new species:H.nanj...The diversity and distribution of Hippodonta species on the coast of China are largely unknown due to limited investigations.In this paper,we report the detailed morphology and ultrastructure of two new species:H.nanjiensis sp.nov.,collected from intertidal sandy sediments of Nanji Islands,the East China Sea and H.qingdaoensis sp.nov.,collected from intertidal sandy sediments of the No.1 Bathing Beach in Qingdao City,the Yellow Sea.Both species occur mainly in the middle part of the intertidal zone.H.nanjiensis possesses a unique large round central area.H.qingdaoensis differs from congeners in having a unique stria pattern,wherein the areolae in the middle transapical striae are less developed or absent on the primary side of the valve,and two areolae per stria are apparent under light microscopy(LM).This study expands our knowledge of Hippodonta diversity and distribution on the coast of China.展开更多
Since 2015, a novel green tide has been recurring in the coastal areas of Qinhuangdao at the western coast of the Bohai Sea in China, threatening the environment and ecosystem of the Beidaihe seaside holiday resort al...Since 2015, a novel green tide has been recurring in the coastal areas of Qinhuangdao at the western coast of the Bohai Sea in China, threatening the environment and ecosystem of the Beidaihe seaside holiday resort along the coast. Micro-propagules of the green algae including gametes, spores, micro-germlings and micro-vegetative fragments play an important role in the formation of green tides. They serve as a "seed source" of green macroalgae, and their distributions could reflect and influence the "algae source" of green tides. In this study,monthly surveys in the inshore and offshore areas of the Qinhuangdao coast were conducted from April to September 2016 and in January 2017 to investigate the tempo-spatial distribution patterns and the biomass variations of the green algae micro-propagules. The obtained results show that micro-propagules were mainly distributed in the inshore areas with a significantly decreasing abundance towards offshore areas. Their biomass was highest in July and August, and lowest in winter. The areas that were affected by the green tides showed a remarkably higher abundance of micro-propagules compared to other areas. These micro-propagules could serve as the "seed" source of green tides. Their distribution patterns indicate that the green tide in the coastal areas of Qinhuangdao originated locally.展开更多
The spatial-temporal relationship between high-quality source rocks and reservoirs is a key factor when evaluating the formation,occurrence,and prospectivity of tight oil and gas reservoirs.In this study,we analyze th...The spatial-temporal relationship between high-quality source rocks and reservoirs is a key factor when evaluating the formation,occurrence,and prospectivity of tight oil and gas reservoirs.In this study,we analyze the fundamental oil and gas accumulation processes occurring in the Songliao Basin,contrasting tight oil sand reservoirs in the south with tight gas sand reservoirs in the north.This is done using geochemical data,constant-rate and conventional mercury injection experiments,and fluid inclusion analyses.Our results demonstrate that as far as fluid mobility is concerned,the expulsion center coincides with the overpressure zone,and its boundary limits the occurrence of tight oil and gas accumulations.In addition,the lower permeability limit of high-quality reservoirs,controlled by pore-throat structures,is 0.1×10^-3μm^2 in the fourth member of the Lower Cretaceous Quantou Formation(K1q^4)in the southern Songliao Basin,and 0.05×10^-3μm^2 in the Lower Cretaceous Shahezi Formation(K1sh)in the northern Songliao Basin.Furthermore,the results indicate that the formation of tight oil and gas reservoirs requires the densification of reservoirs prior to the main phase of hydrocarbon expulsion from the source rocks.Reservoir“sweet spots”develop at the intersection of high-quality source rocks(with high pore pressure)and reservoirs(with high permeability).展开更多
The seasonal characteristics and formation mechanism of the thermohaline structure of mesoscale eddy in the South China Sea are investigated using the latest eddy dataset and ARMOR3D data. Eddy-centric composites reve...The seasonal characteristics and formation mechanism of the thermohaline structure of mesoscale eddy in the South China Sea are investigated using the latest eddy dataset and ARMOR3D data. Eddy-centric composites reveal that the horizontal distribution of temperature anomaly associated with eddy in winter is more of a dipole pattern in upper 50 m and tends to be centrosymmetric below 50 m, while in summer the distribution pattern is centrosymmetric in the entire water column. The horizontal distribution of eddy-induced salinity anomaly exhibits similar seasonal characteristics, except that the asymmetry of the salinity anomaly is weaker. The vertical distribution of temperature anomaly associated with eddy shows a monolayer structure, while the salinity anomaly demonstrates a triple-layer structure. Further analysis indicates that the vertical distribution of the anomalies is related to the vertical structure of background temperature and salinity fields, and the asymmetry of the anomalies in upper 50 m is mainly caused by the horizontal advection of background temperature and salinity.展开更多
Habitat suitability index(HSI)models have been widely used to analyze the relationship between species abundance and environmental factors,and ultimately inform management of marine species.The response of species abu...Habitat suitability index(HSI)models have been widely used to analyze the relationship between species abundance and environmental factors,and ultimately inform management of marine species.The response of species abundance to each environmental variable is different and habitat requirements may change over life history stages and seasons.Therefore,it is necessary to determine the optimal combination of environmental variables in HSI modelling.In this study,generalized additive models(GAMs)were used to determine which environmental variables to be included in the HSI models.Significant variables were retained and weighted in the HSI model according to their relative contribution(%)to the total deviation explained by the boosted regression tree(BRT).The HSI models were applied to evaluate the habitat suitability of mantis shrimp Oratosquilla oratoria in the Haizhou Bay and adjacent areas in 2011 and 2013–2017.Ontogenetic and seasonal variations in HSI models of mantis shrimp were also examined.Among the four models(non-optimized model,BRT informed HSI model,GAM informed HSI model,and both BRT and GAM informed HSI model),both BRT and GAM informed HSI model showed the best performance.Four environmental variables(bottom temperature,depth,distance offshore and sediment type)were selected in the HSI models for four groups(spring-juvenile,spring-adult,falljuvenile and fall-adult)of mantis shrimp.The distribution of habitat suitability showed similar patterns between juveniles and adults,but obvious seasonal variations were observed.This study suggests that the process of optimizing environmental variables in HSI models improves the performance of HSI models,and this optimization strategy could be extended to other marine organisms to enhance the understanding of the habitat suitability of target species.展开更多
基金National Natural Science Foundation of China for Exploring Key Scientific Instrument(No.41827805)the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(No.RERU2021017)Hainan Province Science and Technology Special Fund(ZDYF2021GXJS210)for providing support。
文摘The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectrometry and X-ray Diffraction.The exposure corrosion experiment of these magnesium alloys was tested in South China Sea and KEXUE vessel atmospheric environment.The corrosion characteristic and mechanism of magnesium alloys of Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were analyzed by weight loss rate,corrosion depth,corrosion products and corrosion morphologies.The electrochemical corrosion tests were also measured in the natural seawater.The comprehensive results showed that Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy existed the best corrosion resistance whether in the marine atmospheric environment and natural seawater environment.That depended on the microstructure,type and distribution of precipitated phases in Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy.Sufficient quantity anodic precipitated phases in the microstructure of Mg-5Y-1.5Nd-4Zn-0.5Zr alloy played the key role in the corrosion resistance.
基金The National Natural Science Foundation of China under contract Nos 41830539 and 41906063the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2022QNLM050203the Taishan Scholars Project Funding under contract No.ts20190963。
文摘Planktonic foraminifer Globigerinoides ruber(white)and Trilobatus sacculifer are the most frequently used mixedlayer dwelling species for reconstructing past oceanic environments.Specifically,the Mg/Ca ratios of these two foraminiferal species have been used for reconstructing tropical/subtropical changes in sea surface temperature(SST).However,these two species have different morphotypes,of which the spatial and temporal differences in Mg/Ca ratios and their influencing factors are still unclear.Our objective is to investigate the potential differences between the Mg/Ca ratios of these different morphotypes of G.ruber(white)and T.sacculifer in the western Philippine Sea(WPS)and determine their implications for the reconstruction of SST and upper-ocean structure.Mg/Ca measurements are made on two basic morphotypes of G.ruber(white)[sensu stricto(s.s.)and sensu lato(s.l.)]and T.sacculifer[with(w)and without(w/o)a sac-like final chamber]on samples of Site MD06-3047B from the WPS.Our results reveal that Mg/Ca ratios of different G.ruber morphotypes show consistent differences;and those of T.sacculifer morphotypes show staged variations since MIS 3.It is suggested to select a single morphotype for reconstructing SST changes using the Mg/Ca ratios of G.ruber and T.sacculifer in the WPS.Furthermore,the Mg/Ca ratios between G.ruber s.s.and G.ruber s.l.[Δ(Mg/Ca)_(G.ruber s.s.-s.l.)]downcore MD06-3047B covaries with indexes of summer monsoon.Combining with the core-top results,showing regional variation of differences in theΔ(Mg/Ca)_(G.ruber s.s.-s.l.)over the western tropical Pacific,we propose thatΔ(Mg/Ca)_(G.ruber s.s.-s.l.)may tend to reflect summer mixed layer depth.
基金Supported by the National Natural Science Foundation of China(Nos.41876171,41506167,41476144)。
文摘The Yellow Sea Cold Water Mass(YSCWM)is a distinct hydrographic phenomenon of the Yellow Sea,and the distribution pattern of meio-and macrobenthos diff ers inside and outside of the YSCWM.However,such a pattern has never been observed in the microbenthic ciliate communities.Therefore,we hypothesized that benthic ciliates followed a similar distribution pattern as meio-and macrobenthos,but this pattern has not been uncovered by morphological methods.We evaluated the diversity and distribution of benthic ciliates at fi ve stations along hydrographic gradients across the YSCWM and adjacent shallow water by using morphology and DNA and complementary DNA(cDNA)high-throughput sequencing of the V4 region of 18S rRNA gene.Results showed that the diversity of benthic ciliates detected by DNA(303 OTUs),and the cDNA(611 OTUs)sequencing was much higher than that detected by the morphological method(79 species).Morphological method detected roughly diff erent ciliate communities inside and outside of the YSCWM,but without statistical signifi cance.No clear pattern was obtained by DNA sequencing.In contrast,cDNA sequencing revealed a distinct distribution pattern of benthic ciliate communities like meioand macrobenthos,which coincided well with the results of the environmental parameter analysis.More than half of the total sequences detected by DNA sequencing belonged to planktonic ciliates,most(if not all)of which were recovered from historic DNA originating through the sedimentation of pelagic forms because none of them were observed morphologically.The irrelevant historic DNA greatly infl uenced the recovery of rare species and thus limited the understanding of the benthic ciliate diversity and distribution.Our research indicates that the methods used have signifi cant eff ects on the investigation of benthic ciliate communities and highlights that cDNA sequencing has great advantages in estimating the diversity and distribution of benthic ciliates,as well as the potential for benthic environmental assessments.
基金The National Natural Science Foundation of China under contract No.41676003.
文摘This paper examines the simplification strategy of retaining only the nonhydrostatic effect of local acceleration in a three-dimensional fully nonhydrostatic model regarding the submesoscale wave phenomenon in the ocean.Elaborate scale analysis of the vertical component of the Reynold-averaged Navier-Stokes(RANS)equation was performed,confirming the rationalization of this simplification.Then,the simplification was implemented in a RANS equation-based nonhydrostatic model NHWAVE(nonhydrostatic WAVE)to make a simplified nonhydrostatic model.Numerical examples were taken to test its performance,including surface sinusoidal waves propagating on an idealized East China Sea topography,tidally induced internal lee waves and small-scale solitary waves.The results show that in a considerably wide range of nonlinear strengths,the simplified nonhydrostatic model can obtain similar results as those in the fully nonhydrostatic model,even for smaller-scale solitary waves.Nonlinearity influences the applicability of the simplification.The stronger the nonlinearity is,the worse the simplified model describes the nonhydrostatic phenomenon.In general,the simplified nonhydrostatic model can simulate surface waves better than internal waves.Improvement of computational efficiency in the simplified nonhydrostatic model is reasonable,reducing the central processing unit time duration in the fully nonhydrostatic model by 16.4%–20.6%.The specially designed algorithm based on the simplified nonhydrostatic equation can remarkably reduce the computational time.
基金the Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology(No.MMRKF201810)the China Geological Survey(Nos.DD20190582,DD20191009,DD20160214)funded by the Shandong Province"Taishan Scholar"Construction Project。
文摘To investigate the nature of gas hydrates in the Makran area,new high-resolution geophysical data were acquired between 2018-2019.The data collected comprise multibeam and two-dimensional multi-channel seismic reflection data.The multibeam bathymetry data show East-North-East(ENE)ridges,piggy-back basins,canyon and channel systems,and the morphology of the abyssal plain.Continuous and discontinuous bottom simulating reflectors(BSRs)occur in the piggy-back basins on most of the seismic profiles available.The BSRs cut the dipping layers with strong amplitude and reversed polarity.Discontinuous BSRs indicate a transition along a dipping high-permeable sand layers from gas-rich segment to the gas hydrate-bearing segment and sugge st alternating sediments of fine and relatively coarse grain size.Double BSRs are highly dynamic and attributed to slumps occurring in the study area.The BSRs induced by slumps are located both at deep and shallow depths,responding to the temperature or pressure variation.For the first time,BSRs are observed in the abyssal plain of the Makran area,being associated with anticline structures,which do not show large spatial continuity and are strongly conditioned by structural conditions such as anticlines and fluid migration pathways,including deep fault,gas chimney,and high-permeable sedimentary layer.Our results may help to assess the gas hydrate potential within the piggy-back basins and to determine the most promising target areas.Moreover,results about the abyssal plain BSR may help to locate hydrocarbon reservoirs in the deep ocean.
基金supported by the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology (Qingdao) (No.2021QNLM020001)the Major Scientific and Technological Projects of Shandong Energy Group (No.SNKJ2022A06-R23)+2 种基金the Funds of Creative Research Groups of China (No.41821002)National Natural Science Foundation of China Outstanding Youth Science Fund Project (Overseas) (No.ZX20230152)the Major Scientific and Technological Projects of CNPC (No.ZD2019-183-003)。
文摘Finite-difference(FD)method is the most extensively employed numerical modeling technique.Nevertheless,when using the FD method to simulate the seismic wave propagation,the large spatial or temporal sampling interval can lead to dispersion errors and numerical instability.In the FD scheme,the key factor in determining both dispersion errors and stability is the selection of the FD weights.Thus,How to obtain appropriate FD weights to guarantee a stable numerical modeling process with minimum dispersion error is critical.The FD weights computation strategies can be classified into three types based on different computational ideologies,window function strategy,optimization strategy,and Taylor expansion strategy.In this paper,we provide a comprehensive overview of these three strategies by presenting their fundamental theories.We conduct a set of comparative analyses of their strengths and weaknesses through various analysis tests and numerical modelings.According to these comparisons,we provide two potential research directions of this field:Firstly,the development of a computational strategy for FD weights that enhances stability;Secondly,obtaining FD weights that exhibit a wide bandwidth while minimizing dispersion errors.
基金We would like to acknowledge all the reviewers and editors and the sponsorship of National Natural Science Foundation of China(42030103)the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(2021QNLM020001-6)the Laoshan National Laboratory of Science and Technology Foundation(LSKJ202203400).
文摘Seismic prediction of cracks is of great significance in many disciplines,for which the rock physics model is indispensable.However,up to now,multitudinous analytical models focus primarily on the cracked rock with the isotropic background,while the explicit model for the cracked rock with the anisotropic background is rarely investigated in spite of such case being often encountered in the earth.Hence,we first studied dependences of the crack opening displacement tensors on the crack dip angle in the coordinate systems formed by symmetry planes of the crack and the background anisotropy,respectively,by forty groups of numerical experiments.Based on the conclusion from the experiments,the analytical solution was derived for the effective elastic properties of the rock with the inclined penny-shaped cracks in the transversely isotropic background.Further,we comprehensively analyzed,according to the developed model,effects of the crack dip angle,background anisotropy,filling fluid and crack density on the effective elastic properties of the cracked rock.The analysis results indicate that the dip angle and background anisotropy can significantly either enhance or weaken the anisotropy degrees of the P-and SH-wave velocities,whereas they have relatively small effects on the SV-wave velocity anisotropy.Moreover,the filling fluid can increase the stiffness coefficients related to the compressional modulus by reducing crack compliance parameters,while its effects on shear coefficients depend on the crack dip angle.The increasing crack density reduces velocities of the dry rock,and decreasing rates of the velocities are affected by the crack dip angle.By comparing with exact numerical results and experimental data,it was demonstrated that the proposed model can achieve high-precision estimations of stiffness coefficients.Moreover,the assumption of the weakly anisotropic background results in the consistency between the proposed model and Hudson's published theory for the orthorhombic rock.
基金Laoshan Laboratory under contract No.LSKJ202203803。
文摘The resource of Fenneropenaeus chinensis has declined sharply due to excessive fishing intensity,ecological changes and diseases.In order to supplement the fishing yield and restore resources of F.chinensis,the relevant authorities have carried out the activities of stock enhancement and releasing.It can increase biomass and recover resources.However,compared with increasing biomass,there were still few reports on its effect on the recovery of resources.Resource recovery is a process related to whether the released individuals can form a reproductive population.Up to now,there has been a lack of evidence whether the released F.chinensis can complete the entire life history,and form reproduction population.In this study,gravid female shrimp after spawning migration were captured from coastal waters of Haiyang,Qingdao,and Yellow Sea.After identifying parentage relationships using simple sequence repeat(SSR)and mtDNA haplotype,it was finally confirmed that there were eight released individuals in the recapture samples.It was confirmed for the first time that at least part of the released F.chinensis can complete overwintering and reproductive migration,and maintain the migration habits as their wild counterparts.Therefore,we infered that the released shrimp can reproduce under natural conditions,these F.chinensis can form reproductive populations theoretically if without human intervention.These results indicated that enhancenment and release activities have a positive effect on resource recovery.
基金provided by the National Key R&D Program of China(2018YFC0311206)the Fundamental Research Funds for the Central Universities of China(202012018).
文摘A novel and reactive oxygen species(ROS)responsive astaxanthin phenylboronic acid derivative(AstaDPBA)was constructed by grafting phenylboronic acid(PBA)onto astaxanthin succinate diester(AstaD),and its chemical structure and physicochemical property were identified.AstaD-PBA could effectively improve the ROS quenching ability in the lipopolysaccharide(LPS)-induced RAW264.7 cell inflammation model.Then,the bioactivity of AstaD-PBA was studied by 4 zebrafish ROS-responsive infl ammatory models induced by LPS,copper(Cu^(2+)),high-fat diet,and dextran sodium sulfate(DSS).The results suggest that AstaD-PBA might have high biosafety and the best effect on ulcerative colitis(UC)induced by DSS.Furtherly,AstaDPBA significantly alleviated and treated weight loss and colonic shrinkage,inhibited infl ammatory cytokines,and maintained microbiota homeostasis to improve UC in C57BL/6J mice.Alistipes and Oscillibacter were expected to be considered UC marker fl ora according to the Metastats analysis and Pearson correlation Mantel test(P<0.01)of 16S rRNA gene sequencing data.In conclusion,AstaD-PBA has been promised to be a functional compound to improve UC and maintain intestinal microbiota homeostasis.
基金supported by the National Natural Science Foundation of China(32072145)。
文摘Trimethylamine N-oxide(TMAO)is a risk factor of various chronic diseases,which was produced by metabolism from precursors to trimethylamine(TMA)in gut and the oxidation from TMA in liver.The TMA generation was influenced by diet,mainly due to the rich TMAO precursors in diet.However,it was still unclear that the effects of different proportion and source of macronutrients in different dietary pattern on the production process of TMAO.Here,the generation of TMA from precursors and TMAO from TMA was determined after single oral choline chloride and intraperitoneal injection TMA,respectively,in mice fed with carbohydrates,proteins and fats in different proportion and sources.The results suggested that the generation of TMAO was increased by low non-meat protein and high fat via enhancing the production of TMAO from TMA,and decreased by plant protein and refined sugar via reducing TMA production from precursors in gut and TMAO transformation from TMA in liver.The high fat and high sugar diets accelerating the development of atherosclerosis did not increase the production of TMAO,the risk factor for atherosclerosis,which indicated that the dietary compositions rather than the elevated TMAO level might be a more key risk factor for atherosclerosis.
基金Supported by the National Natural Science Foundation of China(No.41976012)the Key Research Program of Laoshan Laboratory(LSL)(No.LSKJ 202202502)the Strategic Priority Research Program of Chinese Academy of Sciences(CAS)(No.XDB 42000000)。
文摘The coupling between wind stress perturbations and sea surface temperature(SST)perturbations induced by tropical instability waves(TIWs)in the Pacific Ocean has been revealed previously and proven crucial to both the atmosphere and ocean.However,an overlooked fact by previous studies is that the loosely defined“TIWs”actually consist of two modes,including the Yanai wave-based TIW on the equator(hereafter eTIW)and the Rossby wave-based TIW off the equator(hereafter vTIW).Hence,the individual feedbacks of the wind stress to the bimodal TIWs remain unexplored.In this study,individual coupling relationships are established for both eTIW and v TIW,including the relationship between the TIW-induced SST perturbations and two components of wind stress perturbations,and the relationship between the TIW-induced wind stress perturbation divergence(curl)and the downwind(crosswind)TIW-induced SST gradients.Results show that,due to different distributions of eTIW and vTIW,the coupling strength induced by the eTIW is stronger on the equator,and that by the vTIW is stronger off the equator.The results of any of eTIW and vTIW are higher than those of the loosely defined TIWs.We further investigated how well the coupling relationships remained in several widely recognized oceanic general circulation models and fully coupled climate models.However,the coupling relationships cannot be well represented in most numerical models.Finally,we confirmed that higher resolution usually corresponds to more accurate simulation.Therefore,the coupling models established in this study are complementary to previous research and can be used to refine the oceanic and coupled climate models.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA19060203)the National Natural Science Foundation of China(Nos.42076166,42130411)+4 种基金the Natural Science Foundation of Shandong Province(No.ZR2021QD061)the CAS-CSIRO Project Fund(No.GJHZ1888)the Mount Tai Scholar Climbing Plan to Song SUNthe Innovation Team of Fishery Resources and Ecology in the Yellow Sea and Bohai Sea(No.2020TD01)the Hainan Province Basic and Applied Basic Research Program(Natural Science Field)High-Level Talent Project(No.2019RC353)。
文摘Cyanea nozakii,a common jellyfish distributed in offshore China,has a complex trophic relationship with other zooplankton groups.However,few studies have reported the predation rates and prey selection patterns of C.nozakii medusae on different prey items.Research is also lacking on the intraguild predation of Aurelia coerulea(another common bloom jellyfish in offshore China)by C.nozakii.To address the knowledge gaps,the clearance rates of C.nozakii for different prey items,including copepods(small<1000μm and large>1000μm),fish larvae,and gelatinous prey(hydromedusae,A.coerulea ephyrae,and chaetognaths),were measured.The influence of predator size on the clearance rate was also determined.Additionally,we examined the intraguild predation of C.nozakii on A.coerulea medusae.The clearance rates of C.nozakii varied widely with prey organisms,being independent of prey concentrations.Gelatinous organisms,except for chaetognaths,were captured with considerably high efficiency,followed by fish larvae and copepods,indicating the preferential prey selection of gelatinous organisms by C.nozakii.The clearance rate increased linearly with the cross-sectional area of C.nozakii.Body size in medusae may,to some extents,underpin their capacity to capture more prey by increasing the encounter rate and capture success through ontogeny.C.nozakii preyed voraciously on A.coerulea in high feeding efficiency,but the clearance rate decreased with increasing A.coerulea(as prey)size.This phenomenon of intraguild predation suggests a speculative hypothesis of potential population regulation of A.coerulea by C.nozakii.The information regarding the feeding ecology of C.nozakii reported in this study is important for understanding plankton dynamics in marine ecosystems with extensive occurrences of this jellyfish.
文摘Sea cucumber saponins have attracted more attention in recent years due to biological activities.It is a popular practice to soak sea cucumber in Baijiu at home and being applied to industrial manufacturing in China.However,knowledge of the effect of alcohol on the absorption and metabolism of sea cucumber saponins is limited.The effects of alcohol on digestion,absorption and metabolism of sea cucumber saponins in BALB/c mice were investigated after gavage and tail intravenous injection.The results showed that the content of saponins in serum and liver was significantly higher under the influence of alcohol than that in the control group after oral administration.Alcohol promoted the absorption of sea cucumber saponins prototype as well as inhibited the process of saponins being transformed into deglycositic metabolites in the small intestine.Moreover,sea cucumber saponins remained in circulation for a long time and alcohol slowed down the clearance of sea cucumber saponins under the influence of alcohol after intravenous injection.This confirmed the feasibility of marinating sea cucumber in Baijiu to improve the efficacy of saponins and provides an important theoretical basis for the utilization of sea cucumber and the development of sea cucumber liquor.
基金Supported by the Laoshan Laboratory(No.LSK 202203003)the National Key R&D Program of China(No.2022YFC3104100)。
文摘The basic structure and intraseasonal evolution of currents in the southeastern Andaman Sea was analyzed based on data collected in 2017 from two subsurface moorings(C1 and C5).Periodic variation in the upper ocean currents of the Andaman Sea was investigated by combining observational and satellite data.Mooring observations show that rapid changes of current speed and direction occurred in May and June,with a significant increase in current velocity at the C1 mooring.In the second half of the year,southward flow dominated at the C1 mooring,and alternating northward and southward flows were evident at the C5 mooring during the same period but the northward flow prevailed in boreal winter.In addition,analysis of the power spectra of the upper currents revealed that the tidal period at both moorings is primarily semidiurnal with weaker energy than that of the low-frequency currents.The upper ocean currents at the C1 and C5 moorings exhibited intraseasonal variation of 30-60 d and 120 d,while the zonal current at the C1 mooring exhibited a notable period of approximately 180 d.Further analysis indicated that the variability of currents in the Andaman Sea is influenced primarily by equatorial Kelvin waves and Rossby wave packets.Moreover,our results suggest that equatorial Kelvin waves from the eastern Indian Ocean entered the Andaman Sea in the form of Wyrtki Jets and propagated primarily along two distinct pathways during the observation period.In addition to coastal boundary Kelvin waves,it was found that a branch of the Wyrtki Jet that directly enters the Andaman Sea and flows northward along the slope of the continental shelf,and reflected Rossby wave packets by topography.
基金Supported by the Pilot National Laboratory for Marine Science and Technology(No.2021QNLM040001-2)the Science and Technology Basic Resources Investigation Program(No.2018FY100200)+2 种基金the National Key R&D Program(No.2017YFC1600701)the CAS-CSIRO BAU project of the Chinese Academy of Sciences(No.GJHZ201973)the National Natural Science Foundation of China(No.42106206)。
文摘Lipophilic marine toxins(LMTs)produced by some microalgae in the sea could accumulate in shellfish and pose potential threats to the health of seafood consumers.Phytoplankton and shellfish samples were collected from coastal waters of Weihai in Shandong Peninsula,China in autumn,2020,and screened for lipophilic marine toxins and their potential producers using liquid chromatography-tandem mass spectrometry(LC-MS/MS)analysis and high throughput sequencing of partial DNA(V4 region of the 18S rRNA gene)extracted from phytoplankton.Pectenotoxin-2(PTX2),trace amounts of azaspiracid(AZA1 or AZA40),and 13-desmethyl spirolide C(13-DesMe-C)were detected in phytoplankton samples,while PTX2 and gymnodimine(GYM)were detected in shellfish samples.The toxin content in shellfish samples was much lower than the regulatory limit or values reported previously.Results suggest that lipophilic marine toxins should have low risk in coastal waters of Weihai in autumn.Based on the data of high throughput sequencing,the OTUs were assigned to 5 identified species of Alexandrium,including A.ostenfeldii capable of producing 13-DesMe-C and GYM.Two OTUs were found closely related to the toxic species in genus Dinophysis,but it is impossible to assign them to any identified species due to the low resolving power of the V4 region for Dinophysis.The OTUs could not be assigned to any identified species in the genus Azadinium,suggesting the existence of unidentified species in this region.
基金Supported by the National Natural Science Foundation of China(No.31800171)the CAS President’s International Fellowship for Visiting Scientists(No.2018VBA0035)the Nanji Islands Marine Natural Reserve Project(No.NJKJ-2013-005)。
文摘The diversity and distribution of Hippodonta species on the coast of China are largely unknown due to limited investigations.In this paper,we report the detailed morphology and ultrastructure of two new species:H.nanjiensis sp.nov.,collected from intertidal sandy sediments of Nanji Islands,the East China Sea and H.qingdaoensis sp.nov.,collected from intertidal sandy sediments of the No.1 Bathing Beach in Qingdao City,the Yellow Sea.Both species occur mainly in the middle part of the intertidal zone.H.nanjiensis possesses a unique large round central area.H.qingdaoensis differs from congeners in having a unique stria pattern,wherein the areolae in the middle transapical striae are less developed or absent on the primary side of the valve,and two areolae per stria are apparent under light microscopy(LM).This study expands our knowledge of Hippodonta diversity and distribution on the coast of China.
基金The National Key Research and Development Program of China under contract Nos 2016YFC1402104 and2016YFC1402106the National Natural Science Foundation of China under contract No.41606190+2 种基金the Shandong Natural Science Foundation under contract No.ZR2016DB22the Foundation of Key Laboratory of Integrated Monitoring and Applied Technologies for Marine Harmful Algal Blooms,SOA under contract No.MATHAB201806the Creative Team Project of the Laboratory for Marine Ecology and Environmental Science,Qingdao National Laboratory for Marine Science and Technology under contract No.LMEESCTSP-2018-3
文摘Since 2015, a novel green tide has been recurring in the coastal areas of Qinhuangdao at the western coast of the Bohai Sea in China, threatening the environment and ecosystem of the Beidaihe seaside holiday resort along the coast. Micro-propagules of the green algae including gametes, spores, micro-germlings and micro-vegetative fragments play an important role in the formation of green tides. They serve as a "seed source" of green macroalgae, and their distributions could reflect and influence the "algae source" of green tides. In this study,monthly surveys in the inshore and offshore areas of the Qinhuangdao coast were conducted from April to September 2016 and in January 2017 to investigate the tempo-spatial distribution patterns and the biomass variations of the green algae micro-propagules. The obtained results show that micro-propagules were mainly distributed in the inshore areas with a significantly decreasing abundance towards offshore areas. Their biomass was highest in July and August, and lowest in winter. The areas that were affected by the green tides showed a remarkably higher abundance of micro-propagules compared to other areas. These micro-propagules could serve as the "seed" source of green tides. Their distribution patterns indicate that the green tide in the coastal areas of Qinhuangdao originated locally.
基金supported by the National Natural Science Foundation of China (Nos. 41210005 and 41776081)the National Oil and Gas Major Project of China (No. 2011ZX05007-001)the Applied Basic Research Program of Qingdao (No. 2016239)
文摘The spatial-temporal relationship between high-quality source rocks and reservoirs is a key factor when evaluating the formation,occurrence,and prospectivity of tight oil and gas reservoirs.In this study,we analyze the fundamental oil and gas accumulation processes occurring in the Songliao Basin,contrasting tight oil sand reservoirs in the south with tight gas sand reservoirs in the north.This is done using geochemical data,constant-rate and conventional mercury injection experiments,and fluid inclusion analyses.Our results demonstrate that as far as fluid mobility is concerned,the expulsion center coincides with the overpressure zone,and its boundary limits the occurrence of tight oil and gas accumulations.In addition,the lower permeability limit of high-quality reservoirs,controlled by pore-throat structures,is 0.1×10^-3μm^2 in the fourth member of the Lower Cretaceous Quantou Formation(K1q^4)in the southern Songliao Basin,and 0.05×10^-3μm^2 in the Lower Cretaceous Shahezi Formation(K1sh)in the northern Songliao Basin.Furthermore,the results indicate that the formation of tight oil and gas reservoirs requires the densification of reservoirs prior to the main phase of hydrocarbon expulsion from the source rocks.Reservoir“sweet spots”develop at the intersection of high-quality source rocks(with high pore pressure)and reservoirs(with high permeability).
基金The National Key R&D Program of China under contract No.2017YFC1405100the National Natural Science Foundation of China under contract Nos 41576028,41306032 and 41876030+1 种基金the NSFC-Shandong Joint Fund for Marine Science Research Centers under contract No.U1606405the research fund from FIO-UM Joint Center of Marine Science and Technology
文摘The seasonal characteristics and formation mechanism of the thermohaline structure of mesoscale eddy in the South China Sea are investigated using the latest eddy dataset and ARMOR3D data. Eddy-centric composites reveal that the horizontal distribution of temperature anomaly associated with eddy in winter is more of a dipole pattern in upper 50 m and tends to be centrosymmetric below 50 m, while in summer the distribution pattern is centrosymmetric in the entire water column. The horizontal distribution of eddy-induced salinity anomaly exhibits similar seasonal characteristics, except that the asymmetry of the salinity anomaly is weaker. The vertical distribution of temperature anomaly associated with eddy shows a monolayer structure, while the salinity anomaly demonstrates a triple-layer structure. Further analysis indicates that the vertical distribution of the anomalies is related to the vertical structure of background temperature and salinity fields, and the asymmetry of the anomalies in upper 50 m is mainly caused by the horizontal advection of background temperature and salinity.
基金The National Key R&D Program of China under contract No.2017YFE0104400the National Natural Science Foundation of China under contract No.31772852the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2018SDKJ0501-2。
文摘Habitat suitability index(HSI)models have been widely used to analyze the relationship between species abundance and environmental factors,and ultimately inform management of marine species.The response of species abundance to each environmental variable is different and habitat requirements may change over life history stages and seasons.Therefore,it is necessary to determine the optimal combination of environmental variables in HSI modelling.In this study,generalized additive models(GAMs)were used to determine which environmental variables to be included in the HSI models.Significant variables were retained and weighted in the HSI model according to their relative contribution(%)to the total deviation explained by the boosted regression tree(BRT).The HSI models were applied to evaluate the habitat suitability of mantis shrimp Oratosquilla oratoria in the Haizhou Bay and adjacent areas in 2011 and 2013–2017.Ontogenetic and seasonal variations in HSI models of mantis shrimp were also examined.Among the four models(non-optimized model,BRT informed HSI model,GAM informed HSI model,and both BRT and GAM informed HSI model),both BRT and GAM informed HSI model showed the best performance.Four environmental variables(bottom temperature,depth,distance offshore and sediment type)were selected in the HSI models for four groups(spring-juvenile,spring-adult,falljuvenile and fall-adult)of mantis shrimp.The distribution of habitat suitability showed similar patterns between juveniles and adults,but obvious seasonal variations were observed.This study suggests that the process of optimizing environmental variables in HSI models improves the performance of HSI models,and this optimization strategy could be extended to other marine organisms to enhance the understanding of the habitat suitability of target species.
