Bacteria living in sediments play essential roles in marine ecosystems and deeper insights into the ecology and biogeochemistry of these largely unexplored organisms can be obtained from‘omics’approaches.Here,we cha...Bacteria living in sediments play essential roles in marine ecosystems and deeper insights into the ecology and biogeochemistry of these largely unexplored organisms can be obtained from‘omics’approaches.Here,we characterized metagenome-assembled-genomes(MAGs)from the surface sediment microbes of the Venice Lagoon(northern Adriatic Sea)in distinct sub-basins exposed to various natural and anthropogenic pressures.MAGs were explored for biodiversity,major marine metabolic processes,anthropogenic activity-related functions,adaptations at the microscale,and biosynthetic gene clusters.Starting from 126 MAGs,a non-redundant dataset of 58 was compiled,the majority of which(35)belonged to(Alpha-and Gamma-)Proteobacteria.Within the broad microbial metabolic repertoire(including C,N,and S metabolisms)the potential to live without oxygen emerged as one of the most important features.Mixotrophy was also found as a successful lifestyle.Cluster analysis showed that different MAGs encoded the same metabolic patterns(e.g.,C fixation,sulfate oxidation)thus suggesting metabolic redundancy.Antibiotic and toxic compounds resistance genes were coupled,a condition that could promote the spreading of these genetic traits.MAGs showed a high biosynthetic potential related to antimicrobial and biotechnological classes and to organism defense and interactions as well as adaptive strategies for micronutrient uptake and cellular detoxification.Our results highlighted that bacteria living in an impacted environment,such as the surface sediments of the Venice Lagoon,may benefit from metabolic plasticity as well as from the synthesis of a wide array of secondary metabolites,promoting ecosystem resilience and stability toward environmental pressures.展开更多
频域有限差分(finite difference frequency domain,FDFD)方法是地震波场模拟的常用方法,FDFD地震波场模拟的关键之一是构造能有效压制数值频散的FDFD系数。在已有的构造地震波场模拟FDFD系数的方法中,随一个网格内的波长个数变化的自适...频域有限差分(finite difference frequency domain,FDFD)方法是地震波场模拟的常用方法,FDFD地震波场模拟的关键之一是构造能有效压制数值频散的FDFD系数。在已有的构造地震波场模拟FDFD系数的方法中,随一个网格内的波长个数变化的自适应FDFD系数可以最大程度地压制数值频散。目前计算自适应FDFD系数的方法涉及角度积分、共轭梯度优化、顺序初值选取、光滑正则化等问题,不仅较难实现而且计算效率较低。为了简化自适应FDFD系数的计算并提高相应计算效率,本文提出一种新的计算自适应FDFD系数的方法。所提方法首先将不同离散传播角度的平面波解代入FDFD格式,构造相应的最小二乘问题。由于该最小二乘问题较为病态,常规的基于正规方程组的求解方法难以得到光滑的自适应FDFD系数,本文提出通过QR矩阵分解求解相应超定线性方程组来求解该最小二乘问题。相比已有的基于角度积分、共轭梯度优化、顺序初值选取的计算自适应FDFD系数的方法,所提方法在可以得到光滑自适应FDFD系数的基础上,不仅计算过程更简洁,且计算效率明显提高。数值波场模拟结果表明,基于QR矩阵分解的自适应系数FDFD方法可以达到与基于角度积分、共轭梯度优化、顺序初值选取的自适应系数FDFD方法相同的精度,同时所需的计算时间更少。展开更多
Seafloor and buried reliefs occur along continental margin of the Ross Sea(Antarctica).These features are several kilometres wide and tens of metres high,exhibiting cone or flat-top dome shapes.Previous studies have p...Seafloor and buried reliefs occur along continental margin of the Ross Sea(Antarctica).These features are several kilometres wide and tens of metres high,exhibiting cone or flat-top dome shapes.Previous studies have proposed a volcanic or glacial origin for these formations,but these hypotheses do not account for all the available evidence.In this study,we use morpho-bathymetric data,intermediate resolution multichannel seismic and high resolution chirp profiles,as well as magnetic lines to investigate these clusters of mounds.By employing targeted processing techniques to enhance the geophysical characterization of the seafloor and buried reliefs,and to understand the underlying geological features,we propose that the reliefs are mud volcanoes.Some of these formations appear to be associated with a plumbing system,as indicated by acoustic anomalies linked to sediment containing gas.These formations are likely fed by clayey source rocks of Miocene age.Additionally,other reliefs might be the result of mud mobilisation caused by gravity instability and fluid overpressure.展开更多
南大洋因其面积广阔等优势,能够存储更多的热量和二氧化碳(CO_(2)),因此在全球碳循环及气候变化中的地位十分重要。罗斯海作为南大洋第二大边缘海,是研究古海洋演化的理想海域。本研究采用罗斯海陆坡和海盆区的3根插管沉积物岩芯——BC0...南大洋因其面积广阔等优势,能够存储更多的热量和二氧化碳(CO_(2)),因此在全球碳循环及气候变化中的地位十分重要。罗斯海作为南大洋第二大边缘海,是研究古海洋演化的理想海域。本研究采用罗斯海陆坡和海盆区的3根插管沉积物岩芯——BC008(水深1063 m,长27 cm,年龄6.0~14.8 ka B.P.)、BC010(水深2055 m,长44 cm,年龄0~15.5 ka B.P.)和BC006(水深2120 m,长54 cm,年龄0~22.3 ka B.P.),通过分析其生物硅含量及浮游有孔虫碳同位素比值(Nps-δ^(13)C)的变化发现,生物硅含量在末次冰消期较高,在约16 ka B.P.达到极大值,这指示了冰消期罗斯海海域深层水上涌增强并在约16 ka B.P.最为剧烈。与此同时,Nps-δ^(13)C的负偏,指示了南大洋上涌的水团将溶解的硅酸盐传递至海洋表层的同时,也将碳同位素等化学信号传递至表层海水。深层水上涌在末次冰消期显著增强的趋势,与大气CO_(2)浓度在冰消期之后的急剧上升十分吻合,这进一步验证了冰消期南大洋深层水上涌的假说及其对大气CO_(2)浓度上升的贡献。此外,本研究进一步讨论了引起末次冰消期南大洋深层水上涌的可能触发机制,主要可能因南北两极热量分布不均,导致南半球西风带位置和强度以及大西洋经向翻转流强度发生变化,进而驱动南大洋深层水上涌。展开更多
基金supported by the Natural Science Foundation of Jiangsu Province(Grant No.BK20200021)the National Natural Science Foundation of China(Grant No.42174161 and 41974123)the Natural Science Foundation of Heilongjiang Province of China(YQ2023D005).
文摘Bacteria living in sediments play essential roles in marine ecosystems and deeper insights into the ecology and biogeochemistry of these largely unexplored organisms can be obtained from‘omics’approaches.Here,we characterized metagenome-assembled-genomes(MAGs)from the surface sediment microbes of the Venice Lagoon(northern Adriatic Sea)in distinct sub-basins exposed to various natural and anthropogenic pressures.MAGs were explored for biodiversity,major marine metabolic processes,anthropogenic activity-related functions,adaptations at the microscale,and biosynthetic gene clusters.Starting from 126 MAGs,a non-redundant dataset of 58 was compiled,the majority of which(35)belonged to(Alpha-and Gamma-)Proteobacteria.Within the broad microbial metabolic repertoire(including C,N,and S metabolisms)the potential to live without oxygen emerged as one of the most important features.Mixotrophy was also found as a successful lifestyle.Cluster analysis showed that different MAGs encoded the same metabolic patterns(e.g.,C fixation,sulfate oxidation)thus suggesting metabolic redundancy.Antibiotic and toxic compounds resistance genes were coupled,a condition that could promote the spreading of these genetic traits.MAGs showed a high biosynthetic potential related to antimicrobial and biotechnological classes and to organism defense and interactions as well as adaptive strategies for micronutrient uptake and cellular detoxification.Our results highlighted that bacteria living in an impacted environment,such as the surface sediments of the Venice Lagoon,may benefit from metabolic plasticity as well as from the synthesis of a wide array of secondary metabolites,promoting ecosystem resilience and stability toward environmental pressures.
基金supported by the National Natural Science Foundation of China(No.42174161,No.41974123)China Postdoctoral Science Foundation(No.2022M711004)+1 种基金China National Petroleum Corporation Exploration and Development Research Institute Open Fund(No.822102016)the Jiangsu Province Science Fund for Distinguished Young Scholars(No.BK20200021).
文摘频域有限差分(finite difference frequency domain,FDFD)方法是地震波场模拟的常用方法,FDFD地震波场模拟的关键之一是构造能有效压制数值频散的FDFD系数。在已有的构造地震波场模拟FDFD系数的方法中,随一个网格内的波长个数变化的自适应FDFD系数可以最大程度地压制数值频散。目前计算自适应FDFD系数的方法涉及角度积分、共轭梯度优化、顺序初值选取、光滑正则化等问题,不仅较难实现而且计算效率较低。为了简化自适应FDFD系数的计算并提高相应计算效率,本文提出一种新的计算自适应FDFD系数的方法。所提方法首先将不同离散传播角度的平面波解代入FDFD格式,构造相应的最小二乘问题。由于该最小二乘问题较为病态,常规的基于正规方程组的求解方法难以得到光滑的自适应FDFD系数,本文提出通过QR矩阵分解求解相应超定线性方程组来求解该最小二乘问题。相比已有的基于角度积分、共轭梯度优化、顺序初值选取的计算自适应FDFD系数的方法,所提方法在可以得到光滑自适应FDFD系数的基础上,不仅计算过程更简洁,且计算效率明显提高。数值波场模拟结果表明,基于QR矩阵分解的自适应系数FDFD方法可以达到与基于角度积分、共轭梯度优化、顺序初值选取的自适应系数FDFD方法相同的精度,同时所需的计算时间更少。
文摘Seafloor and buried reliefs occur along continental margin of the Ross Sea(Antarctica).These features are several kilometres wide and tens of metres high,exhibiting cone or flat-top dome shapes.Previous studies have proposed a volcanic or glacial origin for these formations,but these hypotheses do not account for all the available evidence.In this study,we use morpho-bathymetric data,intermediate resolution multichannel seismic and high resolution chirp profiles,as well as magnetic lines to investigate these clusters of mounds.By employing targeted processing techniques to enhance the geophysical characterization of the seafloor and buried reliefs,and to understand the underlying geological features,we propose that the reliefs are mud volcanoes.Some of these formations appear to be associated with a plumbing system,as indicated by acoustic anomalies linked to sediment containing gas.These formations are likely fed by clayey source rocks of Miocene age.Additionally,other reliefs might be the result of mud mobilisation caused by gravity instability and fluid overpressure.
基金supported by the National Natural Science Foundation of China(Grant no.41704109)the Jiangsu Province Outstanding Youth Fund Project(Grant no.BK20200021).
基金supported by the National Natural Science Foundation of China (Nos.41974123,42174161)the Jiangsu Innovation and Entrepreneurship Plan and the Jiangsu Province Science Fund for Distinguished Young Scholars (grant no.BK20200021).
文摘南大洋因其面积广阔等优势,能够存储更多的热量和二氧化碳(CO_(2)),因此在全球碳循环及气候变化中的地位十分重要。罗斯海作为南大洋第二大边缘海,是研究古海洋演化的理想海域。本研究采用罗斯海陆坡和海盆区的3根插管沉积物岩芯——BC008(水深1063 m,长27 cm,年龄6.0~14.8 ka B.P.)、BC010(水深2055 m,长44 cm,年龄0~15.5 ka B.P.)和BC006(水深2120 m,长54 cm,年龄0~22.3 ka B.P.),通过分析其生物硅含量及浮游有孔虫碳同位素比值(Nps-δ^(13)C)的变化发现,生物硅含量在末次冰消期较高,在约16 ka B.P.达到极大值,这指示了冰消期罗斯海海域深层水上涌增强并在约16 ka B.P.最为剧烈。与此同时,Nps-δ^(13)C的负偏,指示了南大洋上涌的水团将溶解的硅酸盐传递至海洋表层的同时,也将碳同位素等化学信号传递至表层海水。深层水上涌在末次冰消期显著增强的趋势,与大气CO_(2)浓度在冰消期之后的急剧上升十分吻合,这进一步验证了冰消期南大洋深层水上涌的假说及其对大气CO_(2)浓度上升的贡献。此外,本研究进一步讨论了引起末次冰消期南大洋深层水上涌的可能触发机制,主要可能因南北两极热量分布不均,导致南半球西风带位置和强度以及大西洋经向翻转流强度发生变化,进而驱动南大洋深层水上涌。