Microbial community structure and diversity in deep-sea hydrothermal vent sediments along the Eastern Lau Spreading Centre

The aim of this study is to investigate microbial structures and diversities in five active hydrothermal fields＇ sediments along the Eastern Lau Spreading Centre （ELSC） in the Lau Basin （southwest Pacific）. Microbial communities were surveyed by denatured gradient gel electrophoresis （DGGE） and clone library analysis of 16S rRNA genes. The differences in microbial community structures among sediment samples from the five deep-sea hydrothermal sites were revealed by DGGE profiles. Cluster analysis of DGGE profiles sepa- rated the five hydrothermal samples into two groups. Four different 16S rRNA gene clone libraries, repre- senting two selected hydrothermal samples （19-4TVG8 and 19-4TVG11）, were constructed. Twenty-three and 32 phylotypes were identified from 166 and 160 bacterial clones respectively, including Proteobacteria, Bacteroidetes, Firmicutes, Nitrospirae and Planctomycetes. The phylum Proteobacteria is dominant in both bacterial libraries with a predominance of Gamma-Proteobacteria. A total of 31 and 25 phylotypes were obtained from 160 and 130 archaeal clones respectively, including Miscellaneous Crenarchaeotic Group, Marine Group Ⅰ and Ⅲ, Marine Benthic Group E, Terrestrial Hot Spring Crenarchaeota and Deep-sea Hy- drothermal Vent Euryarchaeota. These results show a variety of clones related to those involved in sulfur cycling, suggesting that the cycling and utilization of sulfur compounds may extensively occur in the Lau Basin deep-sea hydrothermal ecosystem.

Microbial community structure and nitrogenase gene diversity of sediment from a deep-sea hydrothermal vent field on the Southwest Indian Ridge

A sediment sample was collected from a deep-sea hydrothermal vent field located at a depth of 2 951 m on the Southwest Indian Ridge. Phylogenetic analyses were performed on the prokaryotic community using polymerase chain reaction（PCR） amplification of the 16 S rRNA and nifH genes. Within the Archaea, the dominant clones were from marine benthic group E（MBGE） and marine group I（MGI） belonging to the phyla Euryarchaeota and Thaumarchaeota, respectively. More than half of the bacterial clones belonged to the Proteobacteria, and most fell within the Gammaproteobacteria. No epsilonproteobacterial sequence was observed. Additional phyla were detected including the Actinobacteria, Bacteroidetes, Planctomycetes, Acidobacteria, Nitrospirae, Chloroflexi, Chlorobi, Chlamydiae, Verrucomicrobia, and candidate divisions OD1, OP11, WS3 and TM6, confirming their existence in hydrothermal vent environments. The detection of nifH gene suggests that biological nitrogen fixation may occur in the hydrothermal vent field of the Southwest Indian Ridge. Phylogenetic analysis indicated that only Clusters I and III NifH were present. This is consistent with the phylogenetic analysis of the microbial 16 S rRNA genes, indicating that Bacteria play the main role in nitrogen fixation in this hydrothermal vent environment.

DESIGN OF NOVEL HIGH PRESSURE-RESISTANT HYDROTHERMAL FLUID SAMPLE VALVE

Sampling study is an effective exploration method, but the most extreme environments of hydrothermal vents pose considerable engineering challenges for sampling hydrothermal fluids. Moreover, traditional sampler systems with sample valves have difficulty in maintaining samples in situ pressure. However, decompression changes have effect on microorganisms sensitive to such stresses. To address the technical difficulty of collecting samples from hydrothermal vents, a new bidirectional high pressure-resistant sample valve with balanced poppet was designed. The sample valve utilizes a soft high performance plastic ＂PEEK＂ as poppet. The poppet with inapposite dimension is prone to occur to plastic deformation or rupture for high working pressure in experiments. To address this issue, based on the fmite element model, simulated results on stress distribution of the poppet with different structure parameters and preload spring force were obtained. The static axial deformations on top of the poppet were experimented. The simulated results agree with the experimental results. The new sample valve seals well and it can withstand high working pressure.

A Lagrangian Particle Random Walk Model for Simulating A Deep-Sea Hydrothermal Plume with both Buoyant and Non-Buoyant Features

This paper presents a computational model of simulating a deep-sea hydrothermal plume based on a Lagrangian particle random walk algorithm. This model achieves the efficient process to calculate a numerical plume developed in a fluid-advected environment with the characteristics such as significant filament intermittency and significant plume meander due to flow variation with both time and location. Especially, this model addresses both non-buoyant and buoyant features of a deep-sea hydrothermal plume in three dimensions, which significantly challenge a strategy for tracing the deep-sea hydrothermal plume and localizing its source. This paper also systematically discusses stochastic initial and boundary conditions that are critical to generate a proper numerical plume. The developed model is a powerful tool to evaluate and optimize strategies for the tracking of a deep-sea hydrothermal plume via an autonomous underwater vehicle （AUV）.

Characterization of DNA polymerase δ from deep-sea hydrothermal vent shrimp Rimicaris exoculata

DNA polymerase δ(Polδ)plays a crucial and versatile role in DNA replication and DNA repair processes.Vent shrimp Rimicaris exoculata is the primary megafaunal community living in hydrothermal vents.In this study,the Polδfrom shrimp Rimicaris exoculata was cloned,expressed and characterized.The results showed that the Polδcatalytic subunit(POLD1),852 amino acids in length,shared high homology with crayfish Procambarus clarkii and shrimp Oratosquilla oratoria.The recombinant POLD1 expressed in Escherichia coli showed that the enzyme was active in a range of 20℃ to 40℃ with an optimum temperature at 25℃ and in a wide range of p H with an optimum at pH 6.0.The activities of POLD1 were significantly enhanced in the presence of Triton-X 100,Tween 20 and Mn^(2+).The K_(m)(dNTP)value of POLD1 was 4.7μmol/L.The present study would be helpful to reveal the characterization of Polδof deep-sea vent animals.

Research on Pressure Tight Sampling Technique of Deep-Sea Shallow Sediment—A New Approach to Gas Hydrate Investigation

Analyzed and calculated are pressure changes and body deformation of the sample inside of the corer in the process of sampling of deep-sea shallow sediment with a non-piston corer for gas hydrate investigation, Two conclusions are drawn： （1） the stress increments associated with the corer through the sampling process do not affect the stabilization of the gas hydrate; （2） the body deformation of the sample is serious and the ＂incremental filling ratio＂ （IFR） is less than unit, For taking samples with in-situ pressure and structure, combining with the design theories of the pressure tight corer, we have designed a kind of piston corer, named the gas hydrate pressure tight piston corer, Several tests on the sea have been conducted. Test results indicate that the piston corer has a good ability of taking sediment samples on the seafloor and maintaining their original in-situ pressure, meeting the requirement of exploration of gas hydrate in deep-sea shallow sediment layers.

The pressure compensation technology of deep-sea sampling based on the real gas state equation

Compressed gas is usually used for the pressure compensation of the deep-sea pressure-maintaining sampler.The pressure and volume of the recovered fluid sample are highly related to the precharged gas. To better understand the behavior of the gas under high pressure, we present a new real gas state equation based on the compression factor Z which was derived from experimental data. Then theoretical calculation method of the pressure and volume of the sample was introduced based on this empirical gas state equation. Finally, the proposed calculation method was well verified by the high-pressure vessel experiment of the sampler under 115 MPa.

A data processing method for MAPR hydrothermal plume turbidity data and its application in the Precious Stone Mountain hydrothermal field

Hydrothermal plume is an important constituent of seabed hydrothermal circulation and is also one of the characteristics of active hydrothermal vents. Portable Miniature Autonomous Plume Recorders （MAPR） attached to a towed deep-sea instrument was used to search for hydrothermal plumes and hydrothermal vents. We introduced the basic principle of MAPR based on deep towing technology to detect plumes, then analyzed the factors affecting the quality of the MAPR data and presented a data correction method for MAPR, including instrument location correction, noise reduction processing, system error elimination and seawater background reduction. Finally we applied the method to analyze MAPR data obtained during the Chinese DY115-21 cruise on R/VDayang Iin the “Precious Stone Mountain” hydrothermal field on the Gala-pagos Microplate. The results provided a better understanding of the distribution of the hydrothermal activ-ity in this field, indicating the presence of a new hydrothermal vent.

On Optimal Frequencies of Acoustic in-situ Detector for Seafloor Hydrothermal Vents

The approach to determine working frequencies of acoustic in-situ detector for seafloor hydrothermal fluid is presented. Based on the research of deep-sea noise and the sound generated by mid-ocean ridge black smoker hydrothermal vents, and on the hydrothermal-vent animal hearing ranges, coupled with influences of suspended particles of hydrothermal on acoustic attenuation under different frequencies, the optimal frequency range for detection of acoustical signal near black smokers is determined. The optimal frequencies providing the maximum ratio of receiver signal to background noise are obtained. We have developed a laboratory experimental setup for the optimal frequencies selection. In particular, we evaluated time-of-flight performance with respect to the source signal parameters of center frequency and bandwidth. The experimental results confirm the effectiveness of our approach. Current results indicate that individual transducers operated in the range of 18 - 25 kHz are immune to most interfering sounds and suitable for our system.

Major and trace element composition of surface sediments from the Southwest Indian Ridge:evidence for the incorporation of a hydrothermal component

Hydrothermal materials in deep-sea sediments provide a robust tracer to the localized hydrothermal activity at mid-ocean ridges. Major, trace and rare earth element（REE） data for surface sediments collected from the ultraslow spreading Southwest Indian Ridge are presented to examine the existence of hydrothermal component.Biogenic carbonate oozes dominate all the sediment samples, with CaO content varying from 85.5% to 89.9% on a volatile-free basis. The leaching residue of bulk sediments by ~5% HCl is compositionally comparable to the Upper Continental Crust（UCC） in SiO_2, Al_2O_3, CaO, MgO, alkali elements（Rb, Cs） and high field strength elements（Nb, Ta, Zr, Hf, Ti）. These detritus-hosted elements are inferred to be prominently derived from the Australian continent by means of eolian dust, while the contribution of local volcaniclastics is insignificant. In addition, the residual fraction shows a clear enrichment in Fe, Mn, and Ba compared with the UCC. Combining the positive Eu anomaly of residual fraction which is opposed to the UCC but the characteristic of hydrothermal fluids and associated precipitates occurred at mid-ocean ridges, the incorporation of localized hydrothermal component can be constrained. REE mixing calculations indicate that more than half REE within the residual fraction（~55%–60%） are derived from a hydrothermal component, which is inferred to be resulted from a diffuse fluid mineralization. The low-temperature diffuse flow may be widely distributed along the slow-ultraslow spreading ridges where crustal faults and fissures abound, and probably have a great mineralization potential.

Accumulator-Based Deep-Sea Microbe Gastight Sampling Technique

The accumulator is used as a pressure compensation device to realize deep-sea microbe gastight sampling. Four key states of the accumulator are proposed to describe the pressure compensation process and a corresponding mathematical model is established to investigate the relationship between the results of pressure compensation and the parameters of the accumulator. Simulation results show that during the falling process of the sampler, the accumulator＇ s real opening pressure is greater than its precharge pressure; when the sampling depth is 6000 m and the accumulator＇ s precharge pressure is less than 30 MPa, to increase the accumulator＇ s precharge pressure can improve pressure compensation results obviously. Laboratory experiments at 60 MPa show that the acctunulator is an effective and reliable pressure compensation device for deep-sea microbe samplers, The success in sea trial at a depth of 2000 m in the South China Sea shows that the mathematical model and laboratory experiment results are reliable.

Dark Color ZnO Quasi-One-Dimensional Nanostructures Grown by Hydrothermal Method and Modulation of their Optical Properties

Zinc oxide has a large energy gap and thus it has potential application in the field of solar cells by tuning the absorption of sunlight. In order to enhance its absorption of sunlight,dark color zinc oxides have been prepared by traditional hydrothermal method directly using a zinc foil as both source and substrate. We found that we could tune the optical properties of ZnO samples by changing the temperature. In particular, increasing temperature could significantly reduce the reflectivity of solar energy in the visible range. We speculate that the phenomenon is relevant to the sharp cone morphology of the ZnO nanorods grown on the surface of Zn foils, which furthermore enhance refraction and reflection of light in the nanorods. The capacity to improve the light absorption of ZnO may have a bright application in raising the efficiency of solar cells.

Microorganisms from deep-sea hydrothermal vents

With a rich variety of chemical energy sources and steep physical and chemical gradients,hydrothermal vent systems offer a range of habitats to support microbial life.Cultivation-dependent and independent studies have led to an emerging view that diverse microorganisms in deep-sea hydrothermal vents live their chemolithoautotrophic,heterotrophic,or mixotrophic life with versatile metabolic strategies.Biogeochemical processes are mediated by microorganisms,and notably,processes involving or coupling the carbon,sulfur,hydrogen,nitrogen,and metal cycles in these unique ecosystems.Here,we review the taxonomic and physiological diversity of microbial prokaryotic life from cosmopolitan to endemic taxa and emphasize their significant roles in the biogeochemical processes in deep-sea hydrothermal vents.According to the physiology of the targeted taxa and their needs inferred from meta-omics data,the media for selective cultivation can be designed with a wide range of physicochemical conditions such as temperature,pH,hydrostatic pressure,electron donors and acceptors,carbon sources,nitrogen sources,and growth factors.The application of novel cultivation techniques with real-time monitoring of microbial diversity and metabolic substrates and products are also recommended.

深海热液采样阀耐高压塑料阀芯研究

为了维持深海采集的热液样品压力,提出了一种耐高压热液采样阀设计方案.针对阀芯在高压差下易发生塑性变形甚至断裂的问题,基于有限元模型仿真分析了不同结构的塑料阀芯应力分布,探讨了不同截面的应力变化情况.分析结果表明,O型圈沟槽尺寸和R2是影响阀芯应力分布的主要因素.实验研究了阀芯顶端的静态变形,阀芯变形的仿真结果与实验结果基本吻合,间接验证了应力分析的结果,表明使用优化结构阀芯的采样阀能够满足深海高压使用要求.

溶胶-水热法制备亚微米4A分子筛

以硅胶湿样和铝矾土为原料,利用溶胶-水热法合成了亚微米4A分子筛,并采用XRD、SEM和FT-IR等分析手段与常规水热法合成的4A分子筛进行了对比。结果表明,采用溶胶-水热法制备的产品,结晶度为96%,形状规则、大小均匀、呈正态分布且分布范围较窄;粒度小于等于1μm的可达到100%;钙离子交换容量为335mgCa-CO3/g(干基)4A分子筛,白度为97%,完全满足洗涤助剂的要求。

冰后期最大海侵以来长江口潮波特性的变化

冰后期最大海侵时 ,现今长江三角洲地区为一巨大河口湾 ,研究古长江河口湾及其周围海域的潮波特性 ,并与现今长江口的进行对比 ,有助于深入了解长江三角洲形成发育的动力过程。根据冰后期最大海侵时古长江河口湾及其周围海域35个计算站一个半日潮周期的潮位、潮流过程曲线得知 ,冰后期最大海侵时古长江河口湾及其周围海域的潮波为驻波以及驻波 前进波混合型。此后 ,随着古长江河口湾被充填、长江口东进南移 ,长江口的潮波也逐渐转变为现今长江口的前进波型。

利用磷肥副产物硅渣制备亚微米4A分子筛

以磷肥副产物硅渣制备的硅胶湿样和氢氧化铝为原料,溶胶-水热法合成了亚微米4A分子筛,采用XRD、SEM和FT-IR等分析手段进行了表征.结果表明采用硅胶湿样制备的产品形状规则、大小均匀;干基分子筛相对于CaCO3的钙离子交换容量为340 mg/g,白度为95%,与常规水热合成法制备的产品相比,其粒度较小、分布范围较窄,钙离子交换容量有很大提高.

太平洋三海区热液烟囱物的地球化学和氧同位素标型特征研究

以成因矿物学的理论和方法 ,运用电子探针、中子活化、常规化学分析和稳定同位素分析等多种地球化学实验测试技术 ,比较系统地研究了太平洋三区四地热液烟囱物的地球化学组成和其变化 ,揭示了研究区不同热液喷发类型中的地球化学标型特征。

太平洋三海区热液烟囱物的地球化学标型特征研究

以成因矿物学的理论和方法 ,运用电子探针、中子活化、常规化学分析和稳定同位素分析等多种地球化学实验测试技术 ,较系统地研究了太平洋三区四地热液烟囱物的地球化学组成和变化 ,揭示了研究区不同热液喷发类型中的地球化学标型特征。高温热液类型的硫化物 ,由高温热液矿物组成 ,除本身富含 Fe,Zn,Cu,Pb等金属元素外 ,氧同位素换算温度也表现最高或中高 ;中低温热液类型的烟囱物 ,金属元素含量较低 ,氧同位素换算温度也表现较低。

记忆合金海底火山口热液采样器

针对海底火山喷发热液的提取,研究开发了一种新型记忆合金海底火山口热液采样器。该采样器是液压元件在特殊环境下的一种新应用。