青海湖底沉积物的矿物物相及有机质保存研究

盐湖沉积环境是烃源岩发育的重要地质环境。本文以青海湖湖底沉积物为例,根据有机质与粘土矿物含量及矿物表面积的关系,分析了矿物学因素对盐湖相富有机质沉积物中有机质保存的影响。研究发现:湖底沉积物中有机质丰富,为上层水中的浮游生物和由河流携带来的陆地高等植物两种来源。矿物物相分析发现沉积物中粘土矿物含量达到32.4%,以伊利石为主。沉积物经密度分离后测试发现,有机碳含量与粘土矿物含量及矿物表面积之间具有很好的正相关性,说明粘土矿物吸附是青海湖底沉积物中有机质的主要赋存形式。

塔里木盆地下寒武统底部高熟海相烃源岩中有机质的赋存状态

近年来的研究证明 ,中新生代未熟 -低熟海相富有机质泥质烃源岩中有机质是通过溶解在水中的分子规模的碳有机质以化学吸附的形式被吸附到矿物表面上和蒙脱石结构层内 .然而 ,对于高熟海相泥质烃源岩中有机质的赋存状态却少有报道 .通过对塔里木盆地下寒统底部高熟海相泥质烃源岩的有机碳含量、矿物表面积、扫描电镜和透射电镜的综合分析 ,得到了其有机质以细小的颗粒状保存于沉积物颗粒之间的结论 .同时 ,通过高熟海相烃源岩与现代未熟海相烃源岩有机质赋存状态的对比 ,提出了值得进一步研究的有关科学问题 .

重液材料多钨酸钠在青海湖沉积物重力分离中的应用

多钨酸钠是一种无毒、易配制、可循环使用、密度高的新型无机重液。本文利用多钨酸钠重液，用离心机重力分离的方法将青海湖沉积物分成低（≮1.9g/cm^3）、中（1.9～2.8g/cm^3）、高（≥2.8g/cm^3）三个密度组分，平均回收率为96.5％。重力分离后的沉积物测试分析发现，有机质主要分布在富粘土矿物的中密度组，揭示了粘土矿物的表面吸附是青海湖底沉积物有机喷的主要赋存形式。

Microbial diversity in cold seep sediments from the northern South China Sea

South China Sea （SCS） is the largest Western Pacific marginal sea. However, microbial studies have never been performed in the cold seep sediments in the SCS. In 2004, ＂SONNE＂ 177 cruise found two cold seep areas with different water depth in the northern SCS. Haiyang 4 area, where the water depth is around 3000 m, has already been confirmed for active seeping on the seafloor, such as microbial mats, authigenic carbonate crusts and bivalves. We investigated microbial abundance and diver- sity in a 5.55-m sediment core collected from this cold seep area. An integrated approach was employed including geochemistry and 16S rRNA gene phylogenetic analyses. Here, we show that microbial abun- dance and diversity along with geochemistry profiles of the sediment core revealed a coupled reaction between sulphate reduction and methane oxidation. Acridine orange direct count results showed that microbial abundance ranges from 105 to 106 cells/g sediment （wet weight）. The depth-related variation of the abundance showed the same trend as the methane concentration profile. Phylogenetic analysis indicated the presence of sulphate-reducing bacteria and anaerobic methane-oxidizing archaea. The diver- sity was much higher at the surface, but decreased sharply with depth in response to changes in the geochemical conditions of the sediments, such as methane, sulphate concentration and total organic carbon. Marine Benthic Group B, Chloroflexi and JS1 were predominant phylotypes of the archaeal and bacterial libraries, respectively.

A review of the microbiology of the Rehai geothermal field in Tengchong,Yunnan Province,China

The Rehai Geothermal Field, located in Tengchong County, in central-western Yunnan Prov- ince, is the largest and most intensively studied geothermal field in China. A wide physicochemical diversity of springs （ambient to -97 ℃; pH from 〈1.8 to≥9.3） provides a multitude of niches for extremophilic microorganisms. A variety of studies have focused on the cultivation, identification, basic physiology, taxonomy, and biotechnological potential of thermophilic microorganisms from Rehai. Ther- mophilic bacteria isolated from Rehai belong to the phyla Firmicutes and Deinococcus-Thermus. Firmicutes include neutrophilic or alkaliphilic Anoxybacillus, Bacillus, Caldalkalibacillus, Caldanaerobacter, Laceyella, and Geobacillus, as well as thermoacidophilic Alicyclobacillus and Sulfobacillus. Isolates from the Deinococcus-Thermus phylum include several Meiothermus and Thermus species. Many of these bacteria synthesize thermostable polymer-degrading enzymes that may be useful for biotech- nology. The thermoacidophilic archaea Acidianus, Metallosphaera, and Sulfolobus have also been isolated and studied. A few studies have reported the isolation of thermophilic viruses belonging to Siphoviridae （TTSP4 and TTSP10） and Fuselloviridae （STSV1） infecting Thermus spp. and Sulfolobus spp., respectively. More recently, cultivation-independent studies using 16S rRNA gene sequences, shotgun metagenomics, or ＂＇functional gene＂ sequences have revealed a mtlch broader diversity of micro- organisms than represented in culture. Studies of the gene and mRNA encoding 113e large subunit of the ammonia monooxygenase （amoA） of ammonia-oxidizing Archaea （AOA） and the tetraether lipid cre- narchaeol, a potential hiomarker for AOA, suggest a wide diversity, but possibly low abundance, of ther- mophilic AOA in Rehai. Finally, we introduce the Tengchong Partnerships in International Research and Education （P1RE） project, an international collaboration between Chinese and U.S. scientists with the goal of promoting international and interdisciplinary cooperation to gain a more holistic and gh〉bal view of life in te^estrial geothermal springs.

Diversity of microbial plankton across the Three Gorges Dam of the Yangtze River,China

The Three Gorges Dam （TGD） of the Yangtze River, China, is one of the largest irrigation and hydroelectric engineering projects in the world. The effects of huge man-made projects like TGD on fauna and macrophyte are obvious, mainly through changes of water dynamics and flow pattern; however, it is less clear how microorganisms respond to such changes. This research was aimed to examine differences in microbial diversity at different seasons and locations （in front of and behind the TGD）. In addition, differences between particle-attached and free-living communities were also examined. The community structures of total and potentially active microorganisms in the water columns behind and in front of the TGD were analyzed with the DNA- and RNA-based 16S rRNA gene phylogenetic approaches over three different seasons. Clone libraries of 16S rRNA genes were prepared after ampli- fication from extracted DNA and, for some samples, after preparing cDNA from extracted rRNA. Differ- ences were observed between sites at different seasons and between free-living and particle-attached communities. Both bacterial and archaeal communities were more diverse in summer than in winter, due to higher nutrient levels and warmer temperature in summer than in winter. Particle-attached micro- organisms were more diverse than free-living communities, possibly because of higher nutrient levels and heterogeneous geochemical micro-environments in particles. Spatial variations in bacterial community structure were observed, i.e., the water reservoir behind the TGD （upstream） hosted more diverse bacte- rial populations than in front of the dam （downstream）, because of diverse sources of sediments and waters from upstream to the reservoir. These results have important implications for our understanding of responses of microbial communities to environmental changes in river ecosystems affected by dam construction.

Occurrence of Highly Mature Organic Matter in Marine Black Shale Petroleum Source Rocks of Basal Cambrian from Northern Tarim Basin, China

More and more evidence indicates that organic matter (OM) in immature organic-rich sediments and sedimentary rocks is chemically adsorbed onto the outer surfaces of minerals and into interlayer (inner) surfaces of smectitic clay minerals in the form of amorphous molecular-scale carbon. But there have been few reports about the occurrence of highly mature OM in marine black shales (petroleum source rocks). The occurrence of highly mature OM in the black shales of basal Cambrian from northern Tarim Basin is studied in this paper. Based on the comprehensive analyses of total organic carbon contents (TOC), maximum thermolysis temperatures (T-max) of OM, mineral surface areas (MSA), and scanning electronic microscopic (SEM) and transmission electronic microscopic (TEM) observations of the black shales, it is concluded that the highly mature OM in the marine black shales of the basal Cambrian from northern Tarim Basin occurs in particulates ranging in size from 1 to 5 μm in diameter. Through the contrast of the occurrence of the highly mature OM in the black shales with that of the immature ones in modern marine continental margin sediments, some scientific problems are proposed, which are worth to study further in detail.

Microbial diversity in two cold springs on the Qinghai-Tibetan Plateau

The microbial diversity in Wuli Area, Qinghai-Tibetan Plateau was investigated using 16S rRNA gene phylogenetic analyses. A total of 117 bacterial and 66 archaeal 16S rRNA gene clones were obtained from the Wuli cold springs, The bacterial clones could be classified into Proteobacteria, Acid- obacteria, Deinococci, Sphingobacteria, Flavobacteria, Nitrospirae, Actinobacteria, Gemmatimona- detes, and unclassified-bacteria; and the archaeal clones could be classified into Crenarchaeota and Thaumarchaeota. Among the major groups, Proteobacteria and Crenarchaeota were dominant in the bacterial and archaeal 16S rRNA gene clone libraries, respectively. The clone sequences obtained in Wuli cold springs were closely related to those from cold habitats, such as snow/ice/soils on high mountains or at high latitude. Especially, the microbial community composition of Wuli Area was more similar to that in Tibetan glaciers than cold environments of other locations. The data presented in this study have impli- cations for a better understanding of microbial diversity in cold springs on the Qinghai-Tibetan Plateau.

Distribution of glycerol dialkyl glycerol tetraethers in Tibetan hot springs

Isoprenoidal glycerol dialkyl glycerol tetraethers （iGDGTs） from the Gulu hot springs （23--83.6 ℃, pH 〉 7） and Yangbajing hot springs （80-128 ℃, pH 〉 7） were analyzed in order to investigate the distribution of archaeal lipids among different hot springs in Tibet. A soil sample from Gulu was incubated at different temperatures and analyzed for changes in iGDGTs to help evaluate whether surrounding soil may contribute to the iGDGTs in hot springs. The sources of bacterial GDGTs （bGDGTs） in these hot springs were also investigated. The results revealed different profiles ofiGDGTs between Gulu and Yangbajing hot springs. Core iGDGTs and polar iGDGTs also presented different patterns in each hot spring. The PCA analysis showed that the structure of polar iGDGTs can be explained by three factors and suggested multiple sources of these compounds. Bivariate correlation analysis showed significant positive correlations between polar and core bGDGTs, suggesting the in situ production of bGDGTs in the hot springs. Furthermore, in the soil incubation experiment, temperature had the most significant influence on concentration of bGDGTs rather than iGDGTs, and polar bGDGTs had greater variability than core bGDGTs with changing temperature. Our results indicated that soil input had little influence on the composition of GDGTs in Tibetan hot springs.

Distinguishing ectomycorrhizal and saprophytic fungi using carbon and nitrogen isotopic compositions

Ectomycorrhizal fungi, a group of widespread symbiotic fungi with plant, obtain carbon source from trees and improve plant mineral nutrient uptake with their widespread hyphal network. Ectomycorrhizal fungi can be used as inoculants to improve the survival rates of plantation. Saprophytic fungi use the nutrition from the debris of plant or animals, and it is difficult to distinguish the saprophytic and ectomycorrhizal fungi by morphological and anatomic methods. In this research, the differences of stable carbon and nitrogen isotopic compositions of these fungi were analyzed. The results showed that the abundances of 13C of were higher than those of ectomycorrhizal fungi and the abundances of 15N of saprophytic fungi were lower than those of ectomycorrhizal fungi. Such differences of stable carbon and nitrogen isotopic compositions between ectomycorrhizal fungi and saprophytic fungi can be ascribed to their different nutrition sources and ecological functions. These results collectively indicate that stable carbon and nitrogen isotopic compositions are an effective proxy for distinguishing between ectomycorrhizal and saprophytic fungi.

Rapid accuracy determining DNA purity and concentration in heavy oils by spectrophotometry methods

DNA analysis is the core of biotechnology applied in petroleum resources and engineering. Traditionally accurate determination of DNA purity and concentration by spectrometer is the first and critical step for downstream molecular biology research. In this study, three different spectrophotometry methods, BPM, NDTT and NPMTTZ were compared for their performance in determining DNA concentration and purity in 32 oil samples, and molecule methods like quantitative real-time PCR (qPCR) and high-throughput sequence were also performed to help assess the accuracy of the three methods in determining DNA concentration and purity. For ordinary heavy oil (OHO), extra heavy oil (EHO) and super heavy oil (SHO), the characteristics of high viscosity (η), density (ρ) and resin plus asphaltene content will affect the DNA extraction and UV determination. The DNA concentration was decreased as density increased: OHO (11.46 ± 18.34 ng/μL), EHO (6.68 ± 9.67 ng/μL) and SHO (6.20 ± 7.83 ng/μL), and the DNA purity was on the reverse: OHO (1.31 ± 0.27), EHO (1.54 ± 0.20), and SHO (1.83 ± 0.32). The results suggest that spectrophotometry such as BPM and NPMTTZ are qualitatively favorite methods as the quick non-consumable methods in determining DNA concentration and purity of medium oil and heavy oil.

水圈微生物:推动地球重要元素循环的隐形巨人

生活在水圈环境中的微生物数量巨大、遗传与代谢方式极为多样,它们驱动着地球上重要元素的循环。水圈微生物研究已经成为生命科学与地球科学的研究热点。国家自然科学基金委员会于2017年启动了“水圈微生物驱动地球元素循环的机制”重大研究计划(简称“水圈微生物”计划)。“水圈微生物”计划拟选择典型水圈生境,通过多学科交叉研究,借助新技术、新方法,揭示水圈微生物在物种、群落和生态水平驱动碳氮硫循环的机制及其环境响应,认识水圈微生物在元素地球生物化学循环中的宏观作用。“水圈微生物”计划旨在为应对全球变化、保护水圈生态服务功能、合理利用自然资源提供科学依据,并为推动国民经济与社会的可持续发展提供资源与技术。该计划启动至今,已经取得了可喜的进展。为了系统介绍该领域国内外的最新研究成果,《微生物学报》特别组织了本期“水圈微生物”专刊。

黏土矿物对病毒生物地球化学作用的影响探讨与展望

作为自然界丰度最高的生命体,病毒活跃于海洋、土壤、冰川等各类生态系统.通过侵染细菌、古菌及真核微生物,病毒在调控微生物群落和元素生物地球化学循环过程中扮演着关键角色.在自然环境中,病毒与无机或有机颗粒存在广泛的相互作用.黏土矿物是广泛分布于陆地和海洋环境的无机颗粒,陆地生态系统中的黏土矿物可在大气、河流和冰川的作用下搬运至海洋,并在水体中沉降形成深海沉积物.黏土矿物对病毒具有高度亲和力,影响着环境中病毒的丰度、活性和感染能力.因此,黏土矿物对病毒介导的生物地球化学循环过程有着重要的影响.本文从各类生境中病毒的生态功能、病毒的生物地球化学作用模型和黏土矿物对病毒的吸附作用3个方面进行了概述,并讨论了陆地和海洋生态系统中黏土矿物的吸附作用对病毒功能和生物地球化学作用的潜在影响,提出黏土矿物是影响病毒驱动的生物地球化学循环不可忽视的因素,未来应将黏土矿物作为评估病毒生物地球化学作用的参数之一.

Co-occurrence of nitrite-dependent anaerobic methane oxidizing and anaerobic ammonia oxidizing bacteria in two Qinghai-Tibetan saline lakes

Nitrite-dependent anaerobic methane-oxidiz- ing （n-damo） bacteria and anaerobic ammonia oxidizing （anammox） bacteria are two groups of microorganisms involved in global carbon and nitrogen cycling. In order to test whether the n-damo and anammox bacteria co-occur in natural saline environments, the DNA and cDNA samples obtained from the surficial sediments of two saline lakes （with salinity of 32 and 84 g/L, respectively） on the Tibetan Plateau were PCR-amplified with the use of anammox- and n-damo-specific primer sets, followed by clone library construction and phylogenetic analysis. DNA and cDNA- based clones affiliated with n-damo and anammox bacteria were successfully retrieved from the two samples, indicating that these two groups of bacteria can co-occur in natural saline environments with salinity as high as 84g/L. Our finding has great implications for our understanding of the global carbon and nitrogen cycle in nature.

A comprehensive census of lake microbial diversity on a global scale

Despite recent interest in microbial diversity and community structure of lakes across various spatial scales, a global biogeographic distribution pattern and its controlling factors have not been fully disclosed. Here, we compiled and analyzed 88,334,735 environmental 16S rRNA sequences from 431 lakes across a wide range of geographical distance and environmental conditions(in particular, salinity, 0–373.3 gL^–1). Our results showed that lake sediments inhabit significantly(ANOVA: P<0.001) more diverse microbial communities than lake waters. Non-metric dimensional scaling(NMDS) ordinations indicated that microbial community compositions differed distinctly among sample types(freshwater vs. saline, water vs. sediment) and geographic locations. Mantel and partial Mantel tests showed that microbial community composition in lake water was significantly(P=0.001) correlated with geographic distance, salinity, and pH. Statistical analyses based on neutral community and null models indicated that stochastic processes may play predominant roles in shaping the microbial biogeographic distribution patterns in the studied global lake waters. The dispersal-related stochasticity(e.g., homogenizing dispersal) exhibited a stronger influence on the distribution of microbial community in freshwater lakes than in saline lakes. Overall, this work expands our understanding of the impact of geographic distance, environmental conditions, and stochastic processes on microbial distribution in global lakes.

Microbial diversity accumulates in a downstream direction in the Three Gorges Reservoir

Organic and inorganic materials migrate downstream and have important roles in regulating environmental health in the river networks.However,it remains unclear whether and how a mixture of materials(i.e.,microbial species)from various upstream habitats contribute to microbial community coalescence upstream of a dam.Here we track the spatial variation in microbial abundance and diversity in the Three Gorges Reservoir based on quantitative PCR and 16 S rRNA gene high-throughput sequencing data.We further quantitatively assess the relative contributions of microbial species from mainstem,its tributaries,and the surrounding riverbank soils to the area immediately upstream of the Three Gorges Dam(TGD).We found an increase of microbial diversity and the convergent microbial distribution pattern in areas immediately upstream of TGD,suggesting this area become a new confluence for microbial diversity immigrating from upstream.Indeed,the number of shared species increased from upstream to TGD but unique species decreased,indicating immigration of various sources of microbial species overwhelms local environmental conditions in structuring microbial community close to TGD.By quantifying the sources of microbial species close to TGD,we found little contribution from soils as compared to tributaries,especially for sites closer to TGD,suggesting tributary microbes have greater influence on microbial diversity and environmental health in the Three Gorges Reservoir.Collectively,our results suggest that tracking microbial geographic origin and evaluating accumulating effects of microbial diversity shed light on the ecological processes in microbial communities and provide information for regulating aquatic ecological health.

Iron and lead ion adsorption by microbial flocculants in synthetic wastewater and their related carbonate formation

Although microbial treatments of heavy metal ions in wastewater have been studied, the removal of these metals through incorporation into carbonate minerals has rarely been reported. To investigate the removal of Fe^3＋ and Pb^2＋, two representative metals in wastewater, through the precipitation of carbonate minerals by a microbial flocculant （MBF） produced by Bacillus mucilaginosus. MBF was added to synthetic wastewater containing different Fe^3＋ and Pb^2＋ concentrations, and the extent of flocculation was analyzed. CO2 was bubbled into the mixture of MBF and Fe^3＋/Pb^2＋ to initiate the reaction. The solid substrates were analyzed via X-ray diffraction, transmission electron microscopy and energy dispersive spectroscopy. The results showed that the removal efficiency decreased and the MBF adsorption capacity for metals increased with increasing heavy metal concentration. In the system containing MBF, metals （Fe^3＋ and Pb^2＋）, and CO2, the concentrated metals adsorbed onto the MBF combined with the dissolved CO2, resulting in oversaturation of metal carbonate minerals to form iron carbonate and lead carbonates. These results may be used in designing a method in which microbes can be utilized to combine CO2 with wastewater heavy metals to form carbonates, with the aim of mitigating environmental problems.

Eco-engineering approaches for ocean negative carbon emission

The goal of achieving carbon neutrality in the next 30-40 years is approaching worldwide consensus and requires coordinated efforts to combat the increasing threat of climate change.Two main sets of actions have been proposed to address this grand goal.One is to reduce anthropogenic CO2emissions to the atmosphere,and the other is to increase carbon sinks or negative emissions,i.e.,removing CO2from the atmosphere.Here we advocate eco-engineering approaches for ocean negative carbon emission(ONCE),aiming to enhance carbon sinks in the marine environment.An international program is being established to promote coordinated efforts in developing ONCE-relevant strategies and methodologies,taking into consideration ecological/biogeochemical processes and mechanisms related to different forms of carbon(inorganic/organic,biotic/abiotic,particulate/dissolved) for sequestration.We focus on marine ecosystem-based approaches and pay special attention to mechanisms that require transformative research,including those elucidating interactions between the biological pump(BP),the microbial carbon pump(MCP),and microbially induced carbonate precipitation(MICP).Eutrophic estuaries,hypoxic and anoxic waters,coral reef ecosystems,as well as aquaculture areas are particularly considered in the context of efforts to increase their capacity as carbon sinks.ONCE approaches are thus expected to be beneficial for both carbon sequestration and alleviation of environmental stresses.

Abundance and diversity of candidate division JSl- and Chloroflexi-related bacteria in cold seep sediments of the northern South China Sea

Candidate division JS 1-and Chloroflexi-related bacteria are ubiquitous in various deep marine sediments worldwide, yet almost nothing is known about their abundance and diversity in cold seep sediments. Here, we investigated the abundance and diversity of JS1- and Chloroflexi-related bacteria in a cold seep marine sediment core collected from the northern South China Sea （SCS） with the employment of quantitative polymerase chain reaction （qPCR） and 16S rRNA gene phylogenetic analyses. The qPCR results showed that 16S rRNA gene copies per gram of sediments for the total bacteria and JS 1- and Chloroflexi-related bacteria were at magnitudes of 108 and 106, respectively. The relative abundance of JS 1- and Chloroflexi-related 16S rRNA genes to that of total bacteria was 0.07%-8.78% throughout the core. Phyloge- netic analyses showed that the JS-1 related clone sequences were dominant throughout the core. Our study provided insights into abundance and diversity of JS 1- and Chloroflexi-related bacteria in the northern SCS cold seep sediments.

Tectonomicrobiology:A new paradigm for geobiological research

Geomicrobiology is a sub-discipline of geobiology and emphasizes the interaction between microorganisms and their environment on Earth. There is a need to explicitly emphasize the biogeochemical processes performed by microorganisms associated with Earth's tectonic activities, especially under the framework of the modern theory of plate tectonics. Tectonomicrobiology aims to create a better synergy between microbial and active tectonic processes. This explicit synergy should also foster better communications between solid Earth scientists and life scientists in terms of holistic Earth system dynamics at both tectonic and micro-scales.