查看更多>>摘要：In the sedimentary strata dating of estuarial coastal areas,it is often found that there is phenomenon of time-reversal in strata.The seabed sediments could be liquefied under storm waves.A laboratory wave flume experiment demonstrated that storm-in-duced liquefaction deposits are formed by the oscillations of liquefied sediments.In this paper,the particle size distribution and 210Pbex specific activity of the sediment samples from the liquefaction disturbed zone and adjacent stable zone of the Yellow River Delta were tested.The stratigraphic divisions based on storm liquefaction deposit sequence can effectively explain the vertical changes in par-ticle size and 210Pbex specific activity.Due to the differentiation of particles during the storm induced liquefaction,coarse and fine particles regrouped,which could explain the phenomenon of time-reversal in dating data.
查看更多>>摘要：The precision and reliability of first-arrival picking are crucial for determining the accuracy of geological structure in-version using active source ocean bottom seismometer(OBS)refraction data.Traditional methods for first-arrival picking based on sample points are characterized by theoretical errors,especially in low-sampling-frequency OBS data because the travel time of seismic waves is not an integer multiple of the sampling interval.In this paper,a first-arrival picking method that utilizes the spatial wave-form variation characteristics of active source OBS data is presented.First,the distribution law of theoretical error is examined;adjacent traces exhibit variation characteristics in their waveforms.Second,a label cross-correlation superposition method for extracting high-frequency signals is presented to enhance the first-arrival picking precision.Results from synthetic and field data verify that the pro-posed approach is robust,successfully overcomes the limitations of low sampling frequency,and achieves precise outcomes that are comparable with those of high-sampling-frequency data.
查看更多>>摘要：Mechanical properties of hydrate-bearing fine-grained sediments are crucial to effectively mitigate environmental risks caused by artificial and natural decomposition of natural gas hydrates,and the decomposition can induce laterally confined deformation.To explore the effect of natural gas hydrates on laterally confined compression properties,consolidation tests are conducted on remolded hydrate-free and hydrate-bearing samples by using natural fine-grained sediments collected from the northern South China Sea as the host sediments,and empirical equations are developed based on the analyses of consolidation characteristics.The results show that vertical loading induces a reduction in void ratio,and the reduction increases with decreasing hydrate saturation when samples are subjected to the same vertical stress change.The compression index of samples is about 0.53 whether there is hydrate or not,but the yield stress of samples increases sharply with increasing hydrate saturation once beyond the critical value.The coefficient of volume compression and the coefficient of consolidation of hydrate-bearing samples both increase firstly and then decrease to a relative stable level with increasing vertical stress,and the transition occurs at 200 kPa.The average consolidation degree with elapsed time increases rapidly under low vertical stresses,slowly under median vertical stresses,and under high vertical stresses,the consolidation increases a little faster but still slower than those under low vertical stresses.
查看更多>>摘要：Different from rivers in humid areas,the variability of riverine CO2 system in arid areas is heavily impacted by anthro-pogenic disturbance with the increasing urbanization and water withdrawals.In this study,the water chemistry and the controls of carbonate system in an urbanized river(the Fenhe River)on the semi-arid Loess Plateau were analyzed.The water chemistry of the river water showed that the high dissolved inorganic carbon(DIC)concentration(about 37 mg L-1)in the upstream with a karst land type was mainly sourced from carbonate weathering involved by H2CO3 and H2SO4,resulting in an oversaturated partial pressure of CO2(pCO2)(about 800 μatm).In comparison,damming resulted in the widespread appearance of non-free flowing river segments,and aquatic photosynthesis dominated the DIC and pCO2 spatiality demonstrated by the enriched stable isotope of DIC(δ13CDIC).Especially in the mid-downstream flowing through major cities in warm and low-runoff August,some river segments even acted as an atmospheric CO2 sink.The noteworthy is wastewater input leading to a sudden increase in DIC(>55 mg L-1)and pCO2(>4500 μatm)in the downstream of Taiyuan City,and in cold November the increased DIC even extended to the outlet of the river.Our re-sults highlight the effects of aquatic production induced by damming and urban sewage input on riverine CO2 system in semi-arid areas,and reducing sewage discharge may mitigate CO2 emission from the rivers.
查看更多>>摘要：A comprehensive risk assessment to evaluate the vulnerability of the nearshore cetaceans to increasing marine traffic is lacking.In this study,the risk to Indo-Pacific humpback dolphins(Sousa chinensis)in the main habitats in China was assessed based on a semiquantitative spatial vulnerability analysis.85%of the(sub)population which overlapped with the lanes of ferries and/or cargo vessels,with exposure scores of 1.23±0.31(calculated based on the proportion of sea routes that overlap the dolphin's range).A combination of high exposure to the sea routes and sensitivity to marine traffic would render the(sub)populations to be highly vulnerable(EPRE:5.21 and XM:4.47).A low frequency of vessels and an awareness of the ecology assures a low vulnerability(SH:2.43,EZ:2.73).Uncertainty scores were commonly lower for the higher vulnerable populations,and higher for the lower vulnerable populations,suggesting additional field data and more monitoring are necessary.Six years of field data have been used to analyze the influences of various types of marine traffic on humpback dolphin behavior.Fishing and non-fishing vessels were significantly dif-ferent(χ 2=65.19,p<0.01).The humpback dolphins were attracted by fishing vessels(83.1%)but avoided non-fishing vessels(95.2%).We recommend a management with seasonal and geographical constraints,to balance economic development and environ-mental conservation.
查看更多>>摘要：This study investigated the distribution of microplastics and heavy metals,along with the interaction between the two in the sediments of urban rivers in China.Results showed that the abundance of microplastics ranged from 2412±187.5 to 7638±1312 items kg-1 dry sediment across different survey stations,with an average abundance at(4388±713)items kg-1 dry sediment.Upon further categorization,it was found that transparent fragments were the primary color and type of microplastics present.The potential ecological risk index(RI)of heavy metals in sediments suggested a low level of ecological risk within a majority of the urban rivers studied.Cd was identified as the main potential ecological risk factor in the sediments of the studied areas.There was a relatively good significant linear relationship between the RI of heavy metals and the abundance of microplastics,bolstering the linkage be-tween these two environmental pollutants.However,the concentrations of heavy metals in microplastics were not dependent on their corresponding contents in sediments.In fact,the concentration of Cu,Cd,and As in microplastics were higher than those in the sediments.This finding confirmed that microplastics could serve as carriers of heavy metals and introduce potential risks to aquatic wildlife and human through the food chain.
查看更多>>摘要：Hapalogenys analis(order Lobotiformes)is an economically and ecologically significant fish species.It is a typical se-dentary rocky reef fish and is primarily found in the northern Pacific Ocean.Here,we used Hi-C and PacBio sequencing technique to assemble a high-quality,chromosome-level genome for this species.The 539 Mb genome had a contig N50 with a size of 3.43 Mb,while 755 contigs clustered into 24 chromosomal groups with an anchoring rate of 99.02%.Of the total genomic sequence,132.74 Mb(24.39%)were annotated as repeat elements.A total of 21360 protein-coding genes were identified,of which 20787 genes(97.32%)were successfully annotated to public databases.The BUSCO evaluation indicated that 96.90%of the total orthologous genes were matched.The phylogenetic tree representing H.analis and 14 other bony fish species indicated that the H.analis genome contained 364 expanded gene families related to olfactory receptor activity,compared with the common ancestor of H.analis and Sciaenidae.Comparative genomic analysis further identified 3584 contracted gene families.Branch-site modeling identified 277 genes experi-encing positive selection,which may facilitate the adaptation to rocky reef environments.The genome reported here is helpful for ecological and evolutionary studies of H.analis.
查看更多>>摘要：As a member of mucins family,MUC2 is an important component of mucus,which is characterized by tandem and ir-regular repeat sequences rich in threonine and serine.It is strongly expressed by goblet cells that are involved in innate immunity.Japanese flounder is an economically important marine flatfish.In this study,two homologous genes of MUC2 were identified,named MUC2-1 and MUC2-2.Depending on phylogenetic and structural analysis,MUC2-1 and MUC2-2 were clustered in two clades,re-spectively.Paralichthys olivaceus MUC2-1 showed a closer relationship with MUC2 in the higher vertebrates.Various healthy tis-sues were analyzed to determine the expression patterns,and both MUC2 genes showed high expression levels in the gills and intes-tines.Following Edwardsiella tarda challenge,P.olivaceus MUC2-1 and MUC2-2 both showed significant up-regulated expression in intestine and kidney.Moreover,MUC2-1 was significantly up-regulated in gill cell lines following PGN and polyI:C stimulation,and MUC2-2 was significantly up-regulated in gill cell lines following LPS stimulation.In addition,ISH results revealed that MUC2-1 and MUC2-2 showed the same tissue localization in intestine tissues,but displayed different localization in gill.The siRNA-me-diated knockdown of MUC2-1 and MUC2-2 genes in the gill cell lines of Japanese flounder affected the expressions of galnt family genes and smad pathway members that are related to mucosal immunity.The results provided a valuable insight into understanding the functions of MUC2 on mucosal immune system in response to the invasion of bacterial pathogen.
查看更多>>摘要：Carotenoids play crucial physiological roles in animals.A comprehensive investigation into the mechanism of carotenoid metabolism in oysters will establish a theoretical foundation for further development of its carotenoid-rich traits.However,the in-formation on the function of miRNA in β-carotene metabolism in oysters is limited.To elucidate the mechanisms underlying miRNA regulation of carotenoid metabolism in oysters,we compared the expressions of miRNA in digestive gland tissues of Pacific oyster(Crassostrea gigas)fed with a β-carotene supplemented diet and a normal diet,respectively.A total of 690 candidate miRNAs in the Pacific oyster digestive gland tissues were identified,including 590 known miRNAs and 111 unknown miRNAs.Three differentially expressed miRNAs were obtained in the carotenoid-fed and normal groups,associated to 137 differentially expressed target genes.Moreover,the GO enrichment analysis revealed that the differentially expressed target genes were mainly involved in transmembrane transport activity.KEGG enrichment showed that the differentially expressed target genes were involved in ABC transport.Analysis of the mRNA-miRNA network revealed that novel0025 played a central role in carotenoid metabolism,and it was negatively corre-lated with the expression of 46 mRNAs.In addition,down-regulated expression of novel0025 upregulated the expression of the lipo-protein gene LOC105342186,suggesting a potential regulatory role in carotenoid metabolism.Our results provide useful information for elucidating the miRNA regulation mechanism during carotenoids metabolism in the Pacific oyster.
查看更多>>摘要：With the rapid development of oil,energy,power and other industries,CO2 emissions rise sharply,which will cause a large amount of CO2 in the air be absorbed by the ocean and lead to ocean acidification.The growth and development of organisms can be seriously affected by acidified seawater.Sepia esculenta is a mollusk with high nutritional and economic value and is widely cultured in offshore waters of China.Larvae are the early life forms of the organism and are more vulnerable to changes in the exter-nal environment.Too low pH will lead to some adverse reactions in larvae,which will affect metabolism,immune response and other life activities.In this study,we sequenced the transcriptome of S.esculenta subjected to acidified seawater stress and identified 1072 differentially expressed genes(DEGs).The detected atypical expression of DEGs substantiates cellular malformation and transloca-tion in S.esculenta under low pH stimulation.Simultaneously,this also substantiates the notable impact of ocean acidification on mollusks.These DEGs were used for functional enrichment analysis of GO and KEGG,and the top twenty items of the biological process classification in GO terms and 11 KEGG signaling pathways were significantly enriched.Finally,the constructed protein-protein interaction network(PPI)was used to analyze protein-protein interactions,and 12 key DEGs and 3 hub genes were identified.The reliability of 12 genes was verified by quantitative RT-PCR.A comprehensive analysis of the KEGG signaling pathway and PPI revealed that ocean acidification leads to abnormalities in lipid metabolism in S.esculenta larvae,which can lead to cancer develop-ment and metastasis,accompanied by some degree of inflammation.The results of the study will help to further investigate the phy-siological processes of S.esculenta when stimulated by ocean acidification,and provide a reference to cope with the captive breeding of S.esculenta affected by acidification.
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