Characteristics of dissolved sugars in the Southern Yap Trench from sea surface to hadal zone

2,4,6-Tripyridine-s-triazine(TPTZ)spectrophotometric method was applied to determine the concentrations of dissolved monosaccharides(MCHO),polysaccharides(PCHO),and total carbohydrate(TCHO)in seawater samples collected from sea surface to hadal zone and sediment-seawater interface of the Southern Yap Trench in the Western Pacific Ocean.Results show that the concentrations of MCHO,PCHO,and TCHO ranged from 6.3 to 22.3μmol C/L,1.1 to 25.4μmol C/L,and 12.1 to 44.9μmol C/L,respectively,from the euphotic layer to the hadal zone of the trench.At different sampling stations,the concentrations of MCHO,PCHO,and TCHO in the seawater showed complex vertical variation characteristics,but the overall variation trends were decreasing with water depth.In the Southern Yap Trench,the maximum concentration of MCHO in the seawater appeared in the euphotic layer,and the minimum in the hadal zone.The maximum concentration of PCHO appeared in the euphotic layer,and the minimum in the bathypelagic layer.The water layer where the maxima and minima of the average concentration of TCHO appeared was consistent with that of PCHO.PCHO was the major component of TCHO in the seawater of the Southern Yap Trench.In the seawater from the sediment-seawater interface,the concentrations of MCHO,PCHO,and TCHO ranged from 8.4 to 10.6μmol C/L,3.8 to 5.8μmol C/L,and 12.2 to 15.2μmol C/L,respectively,and MCHO was the major component of TCHO.The key factors affecting the concentration and existing forms of dissolved sugars in the seawater of the Southern Yap Trench included photosynthesis,respiration,polysaccharide hydrolysis,adsorption and desorption of particulate matter,trench“funnel effect”,deep ocean currents,sediment resuspension,and etc.This study provided fundamental data about labile organic matter in abyss and hadal zone of marine environment,which is significant for further understanding of deep-sea organic carbon cycle.

Geochemical characteristics of hadal sediment in the northern Yap Trench

Two sediment cores were retrieved in the hadal zone of the Yap Trench,and their concentrations of six major elements Mg,Al,Ca,Ti,Mn and Fe and nine trace elements Sr,Ba,Pb,V,Cr,Co,Ni,Cu and Zn were determined in inductively coupled plasma atomic emission spectrometry(ICP-AES).According to the vertical distribution profiles of the 15 elements,the correlation of their concentrations,the ratios of Ni/Co,V/Cr,Fe/Al,and Ti/Al,and morphological characteristics of the sediment samples,the implications of the depositional environment and the sediment provenance were analyzed.The results show that the ratio of Ni/Co in all depths of the two sediment cores were below 5,and the ratio of V/Cr were lower than 2,indicating that the depositional environment of the hadal zone in the trench was oxidative and might have inflow of the Antarctic bottom oxygen-rich water.The sediment samples on the eastern side of the trench were siliceous mud mainly composed of diatoms,radiolarian,and sponge needles from surface to deep layer.The vertical profile of the elements,the concentration of TOC and the fossil record indicated that the sediment sample from station Dive113 was well mixed from surface to bottom layer.Based on the correlation of concentrations of the elements,the morphological characteristics of the sediment,and the ratios of Fe/Al and Ti/Al,we inferred that the sediment in the hadal zone of the trench had terrestrial,volcanic,biological,and authigenic sources.Major source of the sediment in the eastern side of the trench were terrestrial;whereas the sediment in the western side of the trench received more volcaniclastic input.

Distribution characteristics of lipids in hadal sediment in the Yap Trench

In this study,cored sediment samples collected by the Jiaolong Submersible at 6779 m depth from the hadal zone of the Yap Trench in May 2016 were sliced in 1-cm interval from top to bottom,and lipids in each sediment layer were quantitatively and qualitatively analyzed.The vertical distribution profiles of the lipids in the sediment sample,their main existing forms,and their possible sources were investigated.The results show that the concentration of lipid in the surface sediment was the highest with the carbon number from 12 to 27,dominated by medium and short-chain lipids.The total concentration of fatty acids in surface sediment was much higher than those in the offshore and deep-sea areas,being up to 325.77μg/g due to the funnel effect caused by the“V”terrain of the trench.Fatty acid 18:0 was the most abundant lipids in the sediment sample.Abnormal high concentrations of fatty acid 18:1ω7 and alkanes indicated the existence of hydrothermal fluids in the study area.In addition,saturated fatty acids and monounsaturated fatty acids existed mainly in free form,and polyunsaturated fatty acids existed mainly in bound form.Most of the alkanes were in bound form,and their major source was autochthounous input.The carbon number of alcohols in the sediment sample ranged from 12 to 20,mainly existed in bound form.The source of fatty acids was mainly autochthonous input,and the neutral lipids had both marine and terrestrial origin.This is the first study of lipids in hadal sediment of the Yap Trench.The results will promote deeper understanding of organic carbon cycle in marine environment.

Water characteristics of abyssal and hadal zones in the southern Yap Trench observed with the submersible Jiaolong

Using observations in an applied cruise of the submersible Jiaolong,water characteristics,geostrophic transport,and turbulent mixing in abyssal and hadal zones of the southern Yap Trench were studied.The spatial structures of deep water show that the abyssal water is cold,saline,and oxygen rich.The hadal water has very small changes in potential temperature and potential density,and a little decrease in salinity and obvious decrease in oxygen.The isotherm,isopycnal,and isohaline are depressed in abyss over the central trench.The turbulent mixing is enhanced in the near-bottom zone and the hadal water on the trench slope,especially at the steep slope,the dissipation rate and diffusivity is strong,which weakens the stratification.The geostrophic flows move southward in the western region of the trench and northward in the eastern region,indicating cyclonic circulation.In the central region of the trench,the water transport is^1.74 Sv southward.In the hadal zone,the northward and southward transports are balanced.Our analysis suggests that the abyssal water in the southern Yap Trench is from Lower Circumpolar Water(LCPW)and the hadal water seems to be of the isolated local water rather than LCPW.

Magnetic properties indicate the sources of hadal sediments in the Yap Trench,northwest Pacific Ocean

Magnetic minerals in marine sediments are often masked by the primary natural remanent magnetization and material source signals.In order to understand sedimentary environment and sources of sediments in the abyss,we studied 126 samples of five bottom surface cores collected by the Jiaolong Submersible at 4000-7000 m in depth during the third stage of the China's 38th Ocean Voyage.The magnetic properties of the sediments were analyzed using Thermosusceptibility(k-T)curves and Day plot.The results show that the magnetic minerals in the sediments of the Yap Trench are mainly maghemite,and the overall magnetic and soft magnetic properties were strong.The magnetic particles of sediments are dominated by pseudo single domains(PSD)grains.The main source of sediment is locally-derived basalt debris and volcanic debris,and the process of sedimentation is gravity-like flow deposition.

Widespread and active piezotolerant microorganisms mediate phenolic compound degradation under high hydrostatic pressure in hadal trenches

Phenolic compounds,as well as other aromatic compounds,have been reported to be abundant in hadal trenches.Although high-throughput sequencing studies have hinted at the potential of hadal microbes to degrade these compounds,direct microbiological,genetic and biochemical evidence under in situ pressures remain absent.Here,a microbial consortium and a pure culture of Pseudomonas,newly isolated from Mariana Trench sediments,efficiently degraded phenol under pressures up to 70 and 60 MPa,respectively,with concomitant increase in biomass.By analyzing a high-pressure(70 MPa)culture metatranscriptome,not only was the entire range of metabolic processes under high pressure generated,but also genes encod-ing complete phenol degradation via ortho-and meta-cleavage pathways were revealed.The isolate of Pseudomonas also contained genes encoding the complete degradation pathway.Six transcribed genes(dmpKLMNOP_(sed))were functionally identified to encode a multicomponent hydroxylase catalyzing the hydroxylation of phenol and its methylated derivatives by heterogeneous expression.In addition,key catabolic genes identified in the metatranscriptome of the high-pressure cultures and genomes of bacterial isolates were found to be all widely distributed in 22 published hadal microbial metagenomes.At microbiological,genetic,bioinformatics,and biochemical levels,this study found that microorganisms widely found in hadal trenches were able to effectively drive phenolic compound degradation under high hydrostatic pressures.This information will bridge a knowledge gap concerning the microbial aromatics degradation within hadal trenches.

Scientific and technological progress in the microbial exploration of the hadal zone

The hadal zone is the deepest point in the ocean with a depth that exceeds 6000 m. Exploration of the biological communities in hadal zone began in the 1950s (the first wave of hadal exploration) and substantial advances have been made since the turn of the twenty-first century (the second wave of hadal exploration), resulting in a focus on the hadal sphere as a research hotspot because of its unique physical and chemical conditions. A variety of prokaryotes are found in the hadal zone. The mechanisms used by these prokaryotes to manage the high hydrostatic pressures and acquire energy from the environment are of substantial interest. Moreover, the symbioses between microbes and hadal animals have barely been studied. In addition, equipment has been developed that can now mimic hadal environments in the laboratory and allow cultivation of microbes under simulated in situ pressure. This review provides a brief summary of recent progress in the mechanisms by which microbes adapt to high hydrostatic pressures, manage limited energy resources and coexist with animals in the hadal zone, as well as technical developments in the exploration of hadal microbial life.

Community structure and activity potentials of archaeal communities in hadal sediments of the Mariana and Mussau trenches

Hadal trenches are the least explored marine habitat on earth. Archaea has been shown to be the dominant group in trench sediments. However, the activity potentials and detailed diversity of these communities as well as their inter-trench variations are still not known. In this study, we combined datasets from two pairs of primers to investigate at high resolution the structure and activity potentials of the archaeal communities in vertically sectioned sediment cores taken from the deepest points of the Mariana (10,853 m) and Mussau (7011 m) trenches. The compositions of the potentially active communities revealed, via 16S ribosomal RNA gene (rDNA) and RNA (rRNA), significant differences between samples. Marine Group I (MGI), with nine identified subgroups, was the most dominant class in the active archaeal communities of the two trenches. Significantly different species composition and vertical variations were observed between the two trenches. Vertical transitions from aerobic MGI α to anaerobic MGI η and υ subgroups were observed in MST but not in MT sediments, which might be related to the faster microbial oxygen consumption in MST. These results provide a better understanding on archaeal activity and diversity in trench sediments.

Characteristics of vertical distributions of methane and dimethylsulphoniopropionate in the southern Yap Trench

Methane(CH_(4) )and dimethylsulphoniopropionate(DMSP)are major carbon and sulfur sources for bacterioplankton in the ocean.We investigated the characteristics of CH_(4) and DMSP in the southern Yap Trench from sea surface to hadal zone in June 2017.We found that concentrations of CH_(4) varied from 1.5 to 4.5 nmol/L with saturation between 94% and 204% in the euphotic layer.Concentrations of dissolved DMSP(DMSPd)ranged from 0.5 to 3.7 nmol/L with higher values in surface water and decreased with depth.Concentrations of particulate DMSP(DMSPp)varied from 0 to 13.6 nmol/L.Concentrations of total DMSP(DMSPt)ranged 2.0-15.2 nmol/L.Their concentrations decreased slightly and reached consistent levels in 200-3000-m depth due probably to heterotrophic bacterial production in marine aphotic and high-pressure environments.An exception occurred around 4000-m depth where their concentrations increased considerably and then decreased in deeper water.This previously unrecognized phenomenon sheds light on the elevated concentrations of DMSP in the abyssal layer that might be affected by the Lower Circumpolar Deep Water(LCPW).Concentrations of CH_(4) in seawater of the Benthic Boundary Layer of the southern Yap Trench were slightly higher than those in the water column at approximate depth,and concentrations of DMSP in seawater of the Benthic Boundary Layer of the southern Yap Trench were not much higher than those in the water column at the approximate depth,indicating that sediment was a weak source of CH_(4) but was not a source of DMSP for seawater in the study area.This study presented clear correlations between CH_(4) and DMSP from sea surface to sea bottom,proving that DMSP might be a potential substrate for CH_(4) not only in oxic surface seawater but also in deep water.

Vertical variations and composition of dissolved free amino acid in the seawater of the Yap Trench in the western Pacific Ocean

The composition and concentration of dissolved free amino acid(DFAA)of seawater samples collected in May 2016 from the surface to the hadal zone of the northern region of the Yap Trench were analyzed by pre-column derivatization of o-phthalaldehyde.Results show that the average concentration of DFAA in the study area was 0.47±0.36μmol/L.In different sampling stations,the concentrations of DFAA with water depth showed complex variation patterns.At the sediment-seawater interface,the concentrations of DFAA in the western side of the trench were obviously higher than that in its eastern side.In the study area,there were no significant correlations between the concentrations of DFAA and the environmental parameters such as concentrations of chlorophyll a(Chl a),dissolved oxygen(DO),pH,and dissolved inorganic nitrogen(DIN),indicating that the concentrations of DFAA in seawater of the trench are affected by many factors,such as photosynthesis,respiration,temperature,pressure,illumination,and circulation.The dominant DFAA are similar in different water layers of sampling stations,including aspartic acid(Asp),glutamic acid(Glu),glycine(Gly),and serine(Ser).The composition of different amino acids,and the relative abundance of acidic,basic,and neutral amino acids might be related to the sources and consumption of various amino acids.Nine pairs of amino acids in the DFAA showed significantly positive relationship by correlation matrix analysis,suggesting that they might share similar biogeochemical processes.The degradation index(DI)of the DFAA in seawater of the Yap Trench could reflect the degradation,source,and freshness of DFAA in the trench to some extents.This is a preliminary study of amino acids from sea surface to hadal zone in the ocean,more works shall be done in different trenches to reveal their biogeochemical characte ristics in extreme marine environme nts.

全海深沉积物保压取样装置设计及试验研究

为了实现全海深沉积物保压取样,提出基于着陆器的自密封式全海深沉积物保压取样系统。取样系统主要由深海充油电机、传动机构、取样机构、保压筒、蓄能器、压力传感器和多个高压针阀及不锈钢毛细管组成。为取样器在海底自主取样提供动力,设计了专用于深海超高压的水下电池。整套装置总重60 kg,其中,水下重量45kg。通过设计花瓣压缩环形取样、下端自封闭、两端自平衡的新型取样机构,简化了装置的结构,减轻了装置重量。通过对取样器贯入过程的分析和计算,得到最大贯入力的值为786.5 N。搭建了贯入试验台架以模拟沉积物的取样过程,在不同性质的黏土中测试取样器的取样能力和贯入力,试验结果与计算结果相符合。对于硬塑性、塑性和流塑性3种黏土,取样器的取样体积分别为410、120和20 mL,最大贯入力分别为720、210和20 N。为验证取样器保压筒的密封性能和强度,进行了110 MPa内压试验,保压120 min无压降。为验证取样器在高压下的工作稳定性及保压性能,在60 MPa和100 MPa高压舱内进行了多次测试,试验结果表明,60 MPa下保压率超过90%,100 MPa保压率超过88%。最后,在中国2021大洋科考TS21航次中,取样器搭载“奋斗者号”载人潜器在西菲律宾盆区和马里亚纳海沟进行了3次原位测试,所提出的取样器均完成保取样任务,保压率超过80%,共获取保压沉积物样品超过700 mL。

鲸落生态研究进展与展望

鲸落是指须鲸(Balaenoptera)和抹香鲸(Physeter macrocephalus)等大型鲸类死亡后,尸体沉入海底,形成的一个长期以鲸尸为营养源的生态系统。鲸落研究始于1987年,迄今已经积累了一些生态认识,对这些认识的梳理将为我国即将兴起的鲸落研究提供借鉴。鲸落的演替可分为移动清道夫、机会主义者、化能自养和礁岩阶段,促进、耐受和抑制作用是推动不同阶段演替的主要生态因子,而水深、水温和地理位置对各演化阶段的物种组成和群落结构具有重要影响。目前尚未在移动清道夫阶段发现鲸落专性物种,但已经在机会主义者和化能自养阶段发现了包括食骨虫在内的129种专性物种,这些物种通过洋流将生活史早期产生的浮游幼虫在鲸落间进行扩散。基于全球大型鲸类种群数量和死亡率,有学者粗略估算出相邻且演化阶段相同鲸落的平均距离为5~16 km,这些鲸落随机散布于各大洋海底,可为生物在位置固定、区域距离较远的冷热泉间扩散提供垫脚石,共同维持深海生物多样性水平。有研究认为,捕鲸业对大型鲸类的大肆捕杀导致全球鲸落减少了65%~90%,这已引起深海物种生物多样性水平的严重下降甚至大规模灭绝。鲸落研究极具挑战性,无论探测自然鲸落还是人工植入鲸落都要求配备高性能潜水器和具备熟练深潜作业能力,是一个国家对深海探索能力和综合海洋科技水平的体现。根据国际鲸落研究进展和我国深海探测技术现状,提出我国鲸落研究应充分利用区域优势、聚焦共性科学问题和注重新技术应用的建议。

吉林省重要地质遗迹资源及其分区

为明确吉林省地质遗迹资源的类型、分布和特征,开展吉林省重要地质遗迹调查,按地质遗迹出露分布所在的地貌单元、构造单元将其划分为3个层次,采用单因素评价和综合评价方法对吉林省83处重要地质遗迹进行评价,划分吉林省重要地质遗迹资源区。结果表明:根据地质遗迹出露分布所在的地貌单元、构造单元,按照大区、分区、小区3个层次,将吉林省重要地质遗迹划分为4个地质遗迹大区、9个地质遗迹分区、10个地质遗迹小区。研究成果可为地质遗迹的管理、保护和利用提供基础资料和科学依据。

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。

深海潜水器电源系统的研究现状分析

介绍了深海潜水器的主要类型及目前世界上已成功研制的深海潜水器。综述了近年来无人潜水器和载人潜水器电源系统的研究现状,并对各电源系统进行了分析。指出我国深海潜水器电源系统需要解决的重点技术问题,为我国全海深潜水器的能源系统设计提供帮助和参考。

全海深潜水器的技术现状和发展综述

全海深潜水器是海斗深渊科学研究中不可或缺的深海装备。介绍了国内外全海深无人潜水器及全海深载人潜水器的发展现状,提出了快速潜浮、人—机—环境设计、浮力材料、载人舱设计和制造、大容量蓄电池、全海深通信和定位等全海深载人潜水器未来必须攻克的关键技术。

面向深海潜水器的液压技术发展现状

"蛟龙号"的成功研制使我国深海潜水器技术获得了跨越式的发展,但国际上已经在研制深度更大的全海深载人潜水器。介绍了深海潜水器的基本功能组成,得出深海潜水器所需的液压层面的技术。以此为基础,给出了国内外深海潜水器液压技术的发展现状,包括水液压技术在海洋工程领域的应用。总结了面向深海潜水器液压技术的研究重点问题,为我国全海深潜水器的研究与设计提供帮助与参考。

中国潜水器研究与开发综述（英文）

Given the recent success in the development of several submersibles in China, people's interest in the history of submersible development is increasing. This paper presents the history of submersible development in China, which can be briefly divided into three periods. The first one is the early period of hardship(1971–2000). Many prototype submersibles of HOVs, ROVs, and AUVs were developed at this time, but the main achievement was the establishment of special research organizations and the training of research and development personnel. The second period can be regarded as the quick development period(2001–2015). All currently used submersibles were developed during this period. The most remarkable achievement was the successful development of 7000 m-deep manned submersible "Jiaolong." The third period aims to develop 11 000 m submersibles for challenging the full ocean depth(2016–2020). In this period, two unmanned submersibles and two manned submersibles will be the significant indicators of achievement. If this 5-year plan can be successfully completed, China can play a significant role in the investigation of the deepest part of the oceans, namely, the hadal trenches(6500–11 000 m).

我国载人深渊器的发展策略及当前进展

文中简要介绍了载人深渊器的概念;阐述了我国研制载人深渊器的意义;总结了"蛟龙号"的经验与启示;提出了我国载人深渊器的发展策略并综述了目前所取得的进展.

新生研讨课《走进深渊》教学探索

本文针对新生研讨课《走进深渊》开设的必要性、课程教学内容与实践、课程组织方法及其特色进行了详细的分析阐述,旨在通过师生的交流与探讨,有效地培养学生的批判思维、自主学习习惯、学习能力、创新能力和综合素质,提升学生对学科专业的认知能力,适应大学的学习生活,热爱专业,热爱海洋。