雅浦海沟海参(Synallactidae)肠道微生物多样性及系统进化分析

为研究超深渊海参肠道微生物多样性,了解其所在沉积环境的物质循环特征,利用MiSeq高通量测序技术,对雅浦海沟海参肠道微生物16S rDNA的V3-V4和V4-V5可变区基因序列进行了扩增,并与近岸养殖刺参(Apostichopus japonicus)肠道微生物的多样性和组成进行比较。实验结果显示,与养殖刺参比雅浦海沟海参肠道细菌的多样性(辛普森指数和Chao1指数)和丰富度(ACE指数和香农指数)均较低;雅浦海沟海参肠道细菌主要包括γ-变形菌(Gammaproteobacteria,34.1%)、α-变形菌(Alphaproteobacteria,16.0%)和拟杆菌(Bacteroidetes,24.0%),古菌主要由奇古菌门(Thaumarchaeota,98.8%)组成;雅浦海沟海参肠道中,化能自养的氨氧化古菌亚硝化侏儒菌属(Nitrosopumilus)相对丰度达95.6%,甲基营养的硝酸盐还原菌(Methylotenera)相对丰度为10.6%;而养殖海参肠道中硫酸盐还原菌(28.1%)和硫氧化菌硫卵形菌属(Sulfurovum,13.7%)的相对丰度较高。16S rDNA基因序列的系统进化分析结果表明,亚硝化侏儒菌与超深渊沉积环境中奇古菌门亲缘关系最近,且遵循氨氧化古菌从陆地到深海进化的理论;雅浦海沟海参和养殖海参的肠道微生物组成差异可能反映了超深渊和近海沉积环境中氮循环、硫循环特征。本研究可以为揭示超深渊物质循环和能量流动及生命演化提供参考。     

西太平洋雅浦海沟区海水中CH4和DMSP的垂直变化特征

本研究首次探究了西太平洋雅浦海沟北段从表层到超深渊海水中甲烷（CH₄）及二甲基硫（DMS）的前体物质二甲基巯基丙酸内盐（DMSP）的浓度变化情况。结果表明:雅浦海沟海水甲烷浓度变化范围为1.49~3.87 nmol/L。其上层海水甲烷平均浓度最高,有明显的次表层极大现象。雅浦海沟氧最小层海水的甲烷平均浓度最低;在500~1 000 m中层水中甲烷浓度有一定程度的增大,1 000 m以下至底层甲烷浓度继续升高。研究海区溶解态DMSP（DMSPd）和总DMSP（DMSPt）平均浓度的垂直变化随深度呈先增大后减小趋势,颗粒态DMSP（DMSPp）的平均浓度随深度呈波动式变化,在中层达到最大。雅浦海沟CH₄和DMSP浓度垂直变化受浮游生物、微生物、光照、温度、压力、大洋环流等的复杂影响。在真光层海水中,CH₄浓度与DMSPd、DMSPp和DMSPt浓度表现为负相关关系,在200 m至底层海水中,CH₄浓度与DMSPd、DMSPp和DMSPt浓度表现为正相关关系,显示光照条件是造成雅浦海沟不同深度海水CH₄和DMSP浓度相关性差异的关键因素。     

雅浦海沟南缘海底表层矿物碎屑粒度特征及其物源指示

对取自雅浦海沟南缘海域的112个表层沉积物样品,进行了矿物碎屑粒度特征和粒度组分分离分析,探讨了矿物碎屑的来源。结果表明,研究区海底表层沉积物的矿物碎屑主要粒级是粉砂和黏土。使用粒度组分分离方法,由细到粗共分离出四个组分：M1、M2、M3和M4,其中M1和M2为风尘物质,遍布整个研究区;M3和M4为火山碎屑和硅质生物碎屑,主要分布在雅浦海沟和西加洛林海槽附近。雅浦海沟和西加洛林海槽内矿物碎屑偏粗,峰态值偏小,分选差,反映物源复杂;西加洛林海盆内矿物碎屑偏细,峰态值偏小,分选较差,物源多样;西加洛林海脊处矿物碎屑最细,峰态值普遍较大,分选好,优势粒级明显,物源相对单一。从海脊、海盆到海槽与海沟,矿物碎屑粒径变粗,分选变差,物源逐渐变得复杂,表明矿物碎屑分布与构造环境密切相关。     

雅浦–马里亚纳海沟连接处地貌特征研究

雅浦海沟是西太平洋“沟–弧–盆”体系的重要组成部分。在雅浦海沟北部,雅浦海沟与马里亚纳海沟呈典型的垂直相交。本文对该海域的地貌进行了详细的研究。结果表明,两条海沟连接处附近,海沟的水深、形态、剖面等都发生明显变化,且具有分段性,两侧斜坡上拥有隆起、凹陷、断裂等地貌,这些特征与海沟连接处特殊的俯冲位置具有密切的联系;通过地貌特征和板块扩张速度判断,20 Ma前帕里西维拉海盆扩张中心应位于137°35′34″E附近,雅浦海沟很可能是由帕里西维拉海盆暴露出来的扩张中心转变而成。     

雅浦海沟深海沉积物可培养真菌多样性及其反硝化能力研究

自雅浦海沟4个站位的12个沉积物样品中分离得到38株真菌菌株,基于形态观察和ITS序列信息对所得菌株进行分类鉴定,发现它们分别属于青霉属(Penicillium,17株)、曲霉属(Aspergillus,7株)、篮状菌属(Talaromyces,1株)、枝孢属(Cladosporium,6株)、赭霉属(Ochroconis,1株)、Meyerozyma属(1株)、梅拉菌属(Meira,1株)、Cystobasidium属(2株)、Wallemia属(1株)和红酵母属(Rhodotorula,1株)等10个属.其中青霉属、曲霉属和枝孢属菌株为优势菌株,分别占分离菌株总数的44.7%、18.4%和15.8%;而Wallemia属(节担菌纲)菌株是首次从深海环境中分离到.利用PCR技术在分离的深海真菌菌株中检测nir K和P450nor两种反硝化关键酶基因,结果显示nir K基因可在黄曲霉(Aspergillus flavus)、黑曲霉(Aspergillus niger)、杂色曲霉(Aspergillus versicolor)、枝孢菌(Cladosporium sp.)、枝状枝孢(Cladosporium cladosporioides)和产黄青霉(Penicillium chrysogenum)等6种真菌菌株中检测到,而P450nor基因仅在黄曲霉菌株中检测到.同时还通过富集培养方法从上述沉积物样品中分离获得两株反硝化枝孢菌.结果表明,雅浦海沟深海沉积物环境中存在着丰富的真菌资源,它们在深海环境氮循环中起着一定作用,这将增强人们对深海环境可培养真菌多样性及其生态作用的认识.     

西太平洋雅浦海沟区海底热流原位测量

为了解西太平洋雅浦海沟区俯冲带及岛弧两侧的海底热流分布情况,2015年1-3月期间的西太平洋海山航次中,"科学"号利用最新一代Lister型热流探针对该区域开展了海底热流原位测量工作。沿着横跨俯冲带的站位测线,本次进行了10个热流站位测量,共获得8个站位的有效数据。测量结果表明,该地区地温梯度的变化范围为0.011~0.137 Km-1,平均0.089 Km-1,热导率的变化范围为0.58~1.32 Wm-1K-1,热流值则在14.4~118.85 mWm-2之间,平均为68.02 mWm-2。热流值分布显示,雅浦岛弧附近具有较高的热流值,自雅浦岛弧向两侧热流值逐渐降低,低热流区主要分布在帕里西维拉海盆。由于该地区热流测量数据依然稀缺,深入的讨论有待进一步研究。     

沉积环境对雅浦海沟沉积颗粒物组成和分布的影响

通过对西太平洋雅浦海沟不同水深沉积物中总有机碳（TOC）、总氮（TN）、碳稳定同位素（δ13C）、粒度组成和比表面积（SSA）等参数的分析,探讨了雅浦海沟不同水深沉积颗粒物来源、分布及其影响因素的异同。结果表明,雅浦海沟沉积物TOC含量和δ13C平均值分别为（0.34%±0.14%）和（-20.8‰±0.7‰）,其中海洋浮游植物、陆源土壤和维管植物来源有机碳（OC）的贡献分别为（70%±3%）、（22%±3%）和（8%±2%）,且不同水深差异不大,海沟内沉积物的横向输运可能是深部沉积OC的重要输入途径。由于水深更深站位沉积颗粒物中具有更强的微生物活动和在水柱中更长的保留时间,导致其TOC和TN含量较低,但δ13C无明显差异。水深较浅站位TN含量、SSA、粒径组成和中值粒径等参数垂向变化波动较更深站位更为显著,表明海沟沟壁水深较浅处物源输入和沉积环境的不稳定。同时,由于低OC含量、低SSA以及高密度的海底火山喷出岩在海沟水深较浅的沟壁坡折处的广泛分布,导致该区域粒径组成与TOC含量无显著相关性,而较深站位中TOC含量与粉砂呈正相关,与砂和黏土含量呈负相关。整体而言,雅浦海沟沉积物中粉砂粒级颗粒物是OC的主要载体,而SSA是影响海沟沉积OC剖面分布的最重要因素。     

阿塔卡马海沟深渊和非深渊站位的沉积脂肪酸对比研究

深渊海沟作为海洋的最深处,是最不被人了解的地球生态环境之一。有机质的输入、含量和活性对于维持深渊生态系统和深渊生物地球化学循环至关重要。本文利用脂肪酸生物标志物方法,研究了来自阿塔卡马海沟的4个沉积物柱状样(长度为15-35cm),比较了水深2560-7770m的深渊(A5, A10)和非深渊(A1, A9)站位的脂肪酸含量、来源和保存状况。本研究共检测到50种脂肪酸化合物,包括来自陆源有机质的长链饱和脂肪酸,来自海源浮游植物的短链饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸,以及来自细菌的甲基支链脂肪酸。总脂肪酸的平均含量在非深渊站位A1最高[(13.4±2.9)mg/gdws],而深渊站位A5最低[(5.4±2.2)μg/gdws],这可能与各站位的初级生产力和水深有关。在所有站位中,海源脂肪酸均处于主导地位(61.6%±9.2%),其比例显著高于陆源脂肪酸(33.6%±10.7%)和细菌脂肪酸(4.9%±2.3%),表明在阿塔卡马海沟沉积物中脂肪酸主要是海源有机质的贡献。在每个站位,随着沉积物深度的增大,陆源脂肪酸的比例均明显增加,而海源脂肪酸的比例则减少,该结果与脂肪酸指数FA-...     

深渊着陆器技术研究及马里亚纳海沟科考应用

海斗深渊是指海洋中深度超过6 000 m的区域,占据了海洋底部45%的深度范围,是海洋生态系统的重要组成部分,海斗深渊科学代表着当前海洋研究最新的前沿领域。面向海斗深渊科学近海底长时探测与采样应用需求,介绍了我国自主研制的7 000 m级"天涯"号、"海角"号深渊着陆器系统,针对深渊着陆器的装备特点,重点研究了生物原位观测、微生物富集与固定、生物诱捕及沉积物取样等技术。描述了深渊着陆器在马里亚纳海沟开展的试验和科考应用,验证了着陆器及采样技术的可行性、有效性及其对深渊科考的适用性,并取得了多项科考成果。     

雅浦海沟南缘铁锰结核矿物与地球化学特征及其成因研究

本文采用X射线衍射、全岩地球化学和电子探针等测试方法,对雅浦海沟南部附近海域获得的铁锰结核样品进行了显微构造、矿物和地球化学分析,并探讨了其成因。结果表明:铁锰结核的显微构造主要包括平行纹层构造、柱状构造、叠层状构造和同心环状构造;显微构造和探针结果显示铁锰结核在生长初期处于底部海洋动力比较强烈的环境,后期生长环境逐渐趋于稳定;铁锰结核的矿物组分以水羟锰矿、钠水锰矿、石英和钙十字石为主;样品中Fe、Mn元素含量较高且含量比较接近,Cu、Co、Ni和REE相对富集,REE分布模式整体比较平缓并都出现较强的Ce正异常和重稀土元素亏损现象;文中两块铁锰结核都为水成成因,成矿物质主要来自同期的海水沉淀,同时也受一定海底火山物质和陆源风尘物质的影响。     

Morphology and tectonics of the Yap Trench

We conducted swath bathymetry and gravity surveys the whole-length of the Yap Trench, lying on the southeastern boundary of the Philippine Sea Plate. These surveys provided a detailed morphology and substantial insight into the tectonics of this area subsequent the Caroline Ridge colliding with this trench. Horst and graben structures and other indications of normal faulting were observed in the sea-ward trench seafloor, suggesting bending of the subducting oceanic plate. Major two slope breaks were commonly observed in the arc-ward trench slope. The origin of these slope breaks is thought to be thrust faults and lithological boundaries. No flat lying layered sediments were found in the trench axis. These morphological characteristics suggest that the trench is tectonically active and that subduction is presently occurring. Negative peaks of Bouguer anomalies were observed over the arc-ward trench slope. This indicates that the crust is thickest beneath the arc-ward trench slope because the crustal layers on the convergent two plates overlap. Bouguer gravity anomalies over the northern portion of the Yap Arc are positive. These gravity signals show that the Yap Arc is uplifted by dynamic force, even though dense crustal layers underlie the arc. This overlying high density arc possibly forces the trench to have great water depths of nearly 9000 m. We propose a tectonic evolution of the trench. Subduction along the Yap Trench has continued with very slow rates of convergence, although the cessation of volcanism at the Yap Arc was contemporaneous with collision of the Caroline Ridge. The Yap Trench migrated westward with respect to the Philippine Sea Plate after collision, then consumption of the volcanic arc crust occurred, caused by tectonic erosion, and the distance between the arc and the trench consequently narrowed. Lower crustal sections of the Philippine Sea Plate were exposed on the arc-ward trench slope by overthrusting. Intense shearing caused deformation of the accumulated rocks, resulting in their metamorphism in the Yap Arc.     

Petrogenesis and tectonic implication of lavas from the Yap Trench,western Pacific

We present major and trace element data of lava recovered from the northern Yap Trench in the western Pacific and discuss their petrogenesis and tectonic implications within the framework of interactions between the Caroline Ridge and Yap Trench. Rocks were collected from both landward and seaward trench slopes and exhibited geochemical characteristics similar to backarc basin basalt (BABB) and mid-ocean ridge basalt (MORB), including high Fe content, tholeiitic affinity, high TiO2 value at a given FeOT/MgO ratio, Ti/V ratio between 20 and 50, low Ba/Nb ratio and Th/Nb ratio, and trace element patterns commonly displayed by BABB and MORB, which are distinct from arc lava. These rocks seem to have been generated during mantle upwelling and decompression melting at a spreading center. However, compared with typical forearc lava produced by seafloor spreading in the Mariana forearc region, such as the early Eocene forearc basalts and late Neogene forearc lava in the southernmost Mariana Trench, the Yap Trench lava is derived from a more fertile mantle and feature a more minor subduction component; thus, they cannot be the products of forearc mantle decompression melting. We suggest that the landward slope lava represents backarc basin crust that was overthrust onto the forearc lithosphere during the collision of the Caroline Ridge with the Yap Trench (20–25 Ma), which played a key role in the evolution of the Yap subduction system. Moreover, the seaward slope lava represents the subduction plate crust that accreted onto the deep trench during the collision. This collision event resulted in the cessation of Yap Arc magmatism; thus, the Yap Trench volcanic rocks (<25 Ma) previously suggested to be arc magma products may actually represent the nascent island arc lava with a lower subduction component than in the mature Mariana Arc lava.     

Lateral downslope transport and tentative sedimentary organic carbon box model in the southern Yap Trench,western Pacific Ocean

Sediment collapse and subsequent lateral downslope migration play important roles in shaping the habitats and regulating sedimentary organic carbon(SOC) cycling in hadal trenches.In this study,three sediment cores were collected using a human-occupied vehicle across the axis of the southern Yap Trench(SYT).The total organic carbon(TOC) and total nitrogen(TN) contents,δ¹³C,radiocarbon ages,specific surface areas,and grain size compositions of sediments from three cores were measured.We...     

基于碳、氮稳定同位素的雅浦海沟底栖生物食物来源和营养级初探

为了分析雅浦海沟中底栖生物群落的食物来源和营养级,本研究分析了雅浦海沟真光层中浮游植物和浮游动物、海底沉积物和巨型底栖生物（海绵、海参、海蛇尾、海星、海葵和钩虾）中的碳、氮稳定同位素组成。研究发现雅浦海沟真光层中的浮游植物和浮游动物δ13C值[（-22.8±0.4）‰和（-21.8±0.8）‰]和δ15N值[（5.4±0.4）‰和（6.8±0.2）‰]与巨型底栖生物的δ13C值（-20.1‰~-16.8‰）和δ15N值（11.9‰~17.9‰）的差异超过了一个营养级,表明作为底栖生物的初始食物来源的浮游植物和浮游动物在向下输送的过程中经历了食物链传递和细菌的降解。巨型底栖生物的δ15N和δ13C值之间无显著的相关性,此外不同物种之间营养级也存在明显差异,表现为海绵的营养级相对较高（3.4~4.7）,海参（3.3~3.6）、海蛇尾（3.4~3.5）和海星（3.2~3.7）的营养级较为接近,钩虾（2.9~3.3）和海葵（3.1）的营养级则相对略低,反映了底栖生物不同物种之间食物来源的多样化。     

早全新世白令海北部陆坡沉积环境快速变化

理解增暖背景下海洋环境的演化过程是海洋学和气候学一项重要的研究内容。在地质时期,地球经历了多次增暖时段（包括早全新世）,这为认识海洋环境演化过程提供了重要参考。早全新世全球气候经历了快速增暖,并伴随着冰原融化和海平面快速上升,对包括白令海在内的高纬边缘海的沉积过程和海洋环境产生显著影响。白令海发育宽阔的大陆架,毗邻北美大陆,接受来自育空河、阿纳德尔河和库斯科维姆河物质的供给。目前我们对白令海如何响应早全新世气候的认识还存在明显不足。本研究对位于白令海北部陆坡LV63-19-3岩心沉积物中陆源碎屑组份进行了高分辨率调查,结合沉积年龄模型,研究了早中全新世（距今11.7～5.5 ka）白令海北部陆坡陆源沉积演化过程。研究结果显示,在距今11.5～11 ka,白令海北部陆坡沉积速率高达392.9 cm/ka,在距今约9.7 ka以后降至17.2 cm/ka。在距今11～10.7 ka,发现一层厚约40 cm的暗色纹层状沉积层。在高沉积速率时段,沉积物平均粒径较细,距今9 ka以来平均粒径逐渐增大。主微量元素分析结果表明,陆源碎屑沉积物母岩性质以长英质沉积物为主,并存在少量火山碎屑源贡献。白令海北部陆坡高沉积速率事件对应于冰原融水脉冲（MWP）-1B事件（距今11.4～11.1 ka）,并导致白令海陆坡硅质生产力勃发。在距今11～10.7 ka研究区春夏季海冰覆盖增加抑制表层水体氧供给,夏、秋季持续冰川融水和高表层生产力进一步加剧了水体层化和海洋内部消耗,共同促进了纹层状沉积层的形成。距今9 ka以来白令海季节性海冰活动增强,但是陆源碎屑物质质量累积速率则逐渐减小,表明随着海平面上升,供给到研究区的陆源物质减少。我们认为早全新世白令海北部陆坡沉积环境快速变化是海平面、冰融水脉冲事件和季节性海冰活动共同作用的结果,实际上受高纬日射量、北美大陆冰原融化和全球气候变化控制。