Nematoda from the terrestrial deep subsurface of South Africa

Since its discovery over two decades ago, the deep subsurface biosphere has been considered to be the realm of single-cell organisms, extending over three kilometres into the Earth's crust and comprising a significant fraction of the global biosphere. The constraints of temperature, energy, dioxygen and space seemed to preclude the possibility of more-complex, multicellular organisms from surviving at these depths. Here we report species of the phylum Nematoda that have been detected in or recovered from 0.9-3.6-kilometre-deep fracture water in the deep mines of South Africa but have not been detected in the mining water. These subsurface nematodes, including a new species, Halicephalobus mephisto, tolerate high temperature, reproduce asexually and preferentially feed upon subsurface bacteria. Carbon-14 data indicate that the fracture water in which the nematodes reside is 3,000-12,000-year-old palaeometeoric water. Our data suggest that nematodes should be found in other deep hypoxic settings where temperature permits, and that they may control the microbial population density by grazing on fracture surface biofilm patches. Our results expand the known metazoan biosphere and demonstrate that deep ecosystems are more complex than previously accepted. The discovery of multicellular life in the deep subsurface of the Earth also has important implications for the search for subsurface life on other planets in our Solar System.     

非完全配置构造油气藏形成的新解释

淡稳定中国东部油气产量，除使东部老油区、老层系稳产增产外，同时还要加强新区、新层系的研究，渤海湾盆地深层就是新层系勘探的一个重要方面。迄今，人们对油气藏或油气圈闭的认识主要是从中、浅层油气藏研究中总结出来的，随着勘探领域的拓展，深层已成为东部稳产的一个重要的勘探目标，深层油气藏或油气分布控制因素与中、浅层不完全一致，用中、浅层研究方法来指导深层勘探常常事愿违，影响深层开发进度。通过渤海湾盆地东濮凹     

Genomics of cellulosic biofuels

The development of alternatives to fossil fuels as an energy source is an urgent global priority. Cellulosic biomass has the potential to contribute to meeting the demand for liquid fuel, but land-use requirements and process inefficiencies represent hurdles for large-scale deployment of biomass-to-biofuel technologies. Genomic information gathered from across the biosphere, including potential energy crops and microorganisms able to break down biomass, will be vital for improving the prospects of significant cellulosic biofuel production.     

Prokaryotic cells of the deep sub-seafloor biosphere identified as living bacteria

Chemical analyses of the pore waters from hundreds of deep ocean sediment cores have over decades provided evidence for ongoing processes that require biological catalysis by prokaryotes. This sub-seafloor activity of microorganisms may influence the surface Earth by changing the chemistry of the ocean and by triggering the emission of methane, with consequences for the marine carbon cycle and even the global climate. Despite the fact that only about 1% of the total marine primary production of organic carbon is available for deep-sea microorganisms, sub-seafloor sediments harbour over half of all prokaryotic cells on Earth. This estimation has been calculated from numerous microscopic cell counts in sediment cores of the Ocean Drilling Program. Because these counts cannot differentiate between dead and alive cells, the population size of living microorganisms is unknown. Here, using ribosomal RNA as a target for the technique known as catalysed reporter deposition-fluorescence in situ hybridization (CARD-FISH), we provide direct quantification of live cells as defined by the presence of ribosomes. We show that a large fraction of the sub-seafloor prokaryotes is alive, even in very old (16 million yr) and deep (> 400 m) sediments. All detectable living cells belong to the Bacteria and have turnover times of 0.25-22 yr, comparable to surface sediments.     

Abundance and diversity of microbial life in ocean crust

Oceanic lithosphere exposed at the sea floor undergoes seawater-rock alteration reactions involving the oxidation and hydration of glassy basalt. Basalt alteration reactions are theoretically capable of supplying sufficient energy for chemolithoautotrophic growth. Such reactions have been shown to generate microbial biomass in the laboratory, but field-based support for the existence of microbes that are supported by basalt alteration is lacking. Here, using quantitative polymerase chain reaction, in situ hybridization and microscopy, we demonstrate that prokaryotic cell abundances on seafloor-exposed basalts are 3-4 orders of magnitude greater than in overlying deep sea water. Phylogenetic analyses of basaltic lavas from the East Pacific Rise (9 degrees N) and around Hawaii reveal that the basalt-hosted biosphere harbours high bacterial community richness and that community membership is shared between these sites. We hypothesize that alteration reactions fuel chemolithoautotrophic microorganisms, which constitute a trophic base of the basalt habitat, with important implications for deep-sea carbon cycling and chemical exchange between basalt and sea water.     

Constrained circulation at Endeavour ridge facilitates colonization by vent larvae

Understanding how larvae from extant hydrothermal vent fields colonize neighbouring regions of the mid-ocean ridge system remains a major challenge in oceanic research. Among the factors considered important in the recruitment of deep-sea larvae are metabolic lifespan, the connectivity of the seafloor topography, and the characteristics of the currents. Here we use current velocity measurements from Endeavour ridge to examine the role of topographically constrained circulation on larval transport along-ridge. We show that the dominant tidal and wind-generated currents in the region are strongly attenuated within the rift valley that splits the ridge crest, and that hydrothermal plumes rising from vent fields in the valley drive a steady near-bottom inflow within the valley. Extrapolation of these findings suggests that the suppression of oscillatory currents within rift valleys of mid-ocean ridges shields larvae from cross-axis dispersal into the inhospitable deep ocean. This effect, augmented by plume-driven circulation within rift valleys having active hydrothermal venting, helps retain larvae near their source. Larvae are then exported preferentially down-ridge during regional flow events that intermittently over-ride the currents within the valley.     

Endospore abundance, microbial growth and necromass turnover in deep sub-seafloor sediment

Two decades of scientific ocean drilling have demonstrated widespread microbial life in deep sub-seafloor sediment, and surprisingly high microbial-cell numbers. Despite the ubiquity of life in the deep biosphere, the large community sizes and the low energy fluxes in this vast buried ecosystem are not yet understood. It is not known whether organisms of the deep biosphere are specifically adapted to extremely low energy fluxes or whether most of the observed cells are in a dormant, spore-like state. Here we apply a new approach--the D:L-amino-acid model--to quantify the distributions and turnover times of living microbial biomass, endospores and microbial necromass, as well as to determine their role in the sub-seafloor carbon budget. The approach combines sensitive analyses of unique bacterial markers (muramic acid and D-amino acids) and the bacterial endospore marker, dipicolinic acid, with racemization dynamics of stereo-isomeric amino acids. Endospores are as abundant as vegetative cells and microbial activity is extremely low, leading to microbial biomass turnover times of hundreds to thousands of years. We infer from model calculations that biomass production is sustained by organic carbon deposited from the surface photosynthetic world millions of years ago and that microbial necromass is recycled over timescales of hundreds of thousands of years.     

Biodegradation of oil in uplifted basins prevented by deep-burial sterilization.

Biodegradation of crude oil by bacterial activity--which has occurred in the majority of the Earth's oil reserves--is known to reduce greatly the quality of petroleum in reservoirs. For economically successful prospecting for oil, it is therefore important to understand the processes and conditions in geological formations that lead to oil biodegradation. Although recent studies speculate that bacterial activity can potentially occur up to temperatures as high as 150 degrees C (refs 3, 4), it is generally accepted that effective petroleum biodegradation over geological timescales generally occurs in reservoirs with temperatures below 80 degrees C (ref. 2). This appears, however, to be at odds with the observation that non-degraded oils can still be found in reservoirs below this temperature. Here we compile data regarding the extent of oil biodegradation in several oil reservoirs, and find that the extensive occurrence of non-biodegraded oil in shallow, cool basins is restricted to those that have been uplifted from deeper, hotter regions of the Earth. We suggest that these petroleum reservoirs were sterilized by heating to a temperature around 80-90 degrees C during deep burial, inactivating hydrocarbon-degrading organisms that occur in the deep biosphere. Even when such reservoirs are subsequently uplifted to much cooler regions and filled with oil, degradation does not occur, implying that the sterilized sediments are not recolonized by hydrocarbon-degrading bacteria.     

Ploughing the deep sea floor

Bottom trawling is a non-selective commercial fishing technique whereby heavy nets and gear are pulled along the sea floor. The direct impact of this technique on fish populations and benthic communities has received much attention, but trawling can also modify the physical properties of seafloor sediments, water–sediment chemical exchanges and sediment fluxes. Most of the studies addressing the physical disturbances of trawl gear on the seabed have been undertaken in coastal and shelf environments, however, where the capacity of trawling to modify the seafloor morphology coexists with high-energy natural processes driving sediment erosion, transport and deposition. Here we show that on upper continental slopes, the reworking of the deep sea floor by trawling gradually modifies the shape of the submarine landscape over large spatial scales. We found that trawling-induced sediment displacement and removal from fishing grounds causes the morphology of the deep sea floor to become smoother over time, reducing its original complexity as shown by high-resolution seafloor relief maps. Our results suggest that in recent decades, following the industrialization of fishing fleets, bottom trawling has become an important driver of deep seascape evolution. Given the global dimension of this type of fishery, we anticipate that the morphology of the upper continental slope in many parts of the world’s oceans could be altered by intensive bottom trawling, producing comparable effects on the deep sea floor to those generated by agricultural ploughing on land.     

小波分析在泰安—忻州折射/宽角反射剖面解释中的应用

泰安—忻州折射/宽角反射剖面穿过鲁西隆起、华北坳陷、太行山隆起几个构造单元,剖面中段穿过河北省的邢台地震区.利用小波多尺度分析处理了该剖面的几炮波形记录,得到邢台地震区和相邻地段的震相特征.结果表明,邢台地震区的下方莫霍面为复杂结构,可能为双层莫霍面,而在相邻地段莫霍面为较清晰的一级间断面.研究区的深反射剖面结果同样表明,邢台地震区的下方莫霍面为壳幔过渡带,并且在中、上地壳有滑脱构造和延伸到莫霍面的深断裂.复杂的莫霍面结构和形态是邢台地震区的深部构造背景.     

基于启发式规则的Deep Web接口发现

为了有效地利用Deep Web资源,Deep Web数据集成成为当前研究的热点之一.能否高效地发现Deep Web站点是Deep Web数据集成的基础和关键.在此,提出了一种Deep Web接口发现方法,包括基于领域知识来确定合适的查询提交词和用启发式规则发现领域内Deep Web接口.实验结果表明,该方法达到了较高的准确率和召回率,具有良好的可行性和实用性.     

海光缆远程供电系统可靠性研究

设计了一种基于电能分支单元的海光缆远供系统.通过计算海缆的电感、电容及电阻量,将海缆和电力设备等效电路模型编入仿真程序,建立远供系统模型,归纳出远供系统的5种故障类型,并利用专业仿真软件对系统可靠性进行仿真.结果显示,在多种不同故障下系统均能保持串联恒流供电特性,且工作稳定,说明基于电能分支单元的海光缆远程供电系统具有较高的可靠性,能够实际应用于海底观测网络.
     

Exploration technology and development trend of Daqing Oilfield

Exploration for oil and deep gas in northern Songliao Basin,complex rift basin—Hailaer Basin,and Yi-Shu Graben in peripheral basin has technical challenge.Researches on supporting technology including seismic acquisition,processing and interpretation,logging and drilling are performed to establish high resolution 3D seismic technology for lithologic reservoir,deep volcanic rock and complex rift basin,reservoir evaluation and stimulation technology for low permeability reservoir,volcanic reservoir and complex rift reservoir,and drilling technology for deep volcanic rock,providing technical support for reserves increase in northern Songliao Basin,large gas reservoirs discovery in deep volcanic rock and exploration progress in complex rift basin.Next-step development trend of exploration technology is proposed to meet the demand of more technical challenges in the future.     

海藻共附生真菌活性天然产物研究进展

海藻共附生真菌次级代谢产物结构类型多样、骨架新颖、活性丰富,为新型海洋药物先导化合物的发现提供了宝贵的来源。本文以生物活性对海藻共附生真菌来源的天然产物进行分类,从抗菌、抗肿瘤、抗氧化、抗炎、浮游生物抑制等方面,对2006年以来报道的海藻共附生真菌来源的112个活性天然产物进行概述,为海藻及其共附生微生物的进一步研究与开发提供参考。     

The life span of the biosphere revisited

A decade ago, Lovelock and Whitfield raised the question of how much longer the biosphere can survive on Earth. They pointed out that, despite the current fossil-fuel induced increase in the atmospheric CO2 concentration, the long-term trend should be in the opposite direction: as increased solar luminosity warms the Earth, silicate rocks should weather more readily, causing atmospheric CO2 to decrease. In their model, atmospheric CO2 falls below the critical level for C3 photosynthesis, 150 parts per million (p.p.m.), in only 100 Myr, and this is assumed to mark the demise of the biosphere as a whole. Here, we re-examine this problem using a more elaborate model that includes a more accurate treatment of the greenhouse effect of CO2, a biologically mediated weathering parameterization, and the realization that C4 photosynthesis can persist to much lower concentrations of atmospheric CO2(<10 p.p.m.). We find that a C4-plant-based biosphere could survive for at least another 0.9 Gyr to 1.5 Gyr after the present time, depending respectively on whether CO2 or temperature is the limiting factor. Within an additional 1 Gyr, Earth may lose its water to space, thereby following the path of its sister planet, Venus.     

核岩土环境工程问题及研究现状

核废料地下贮置问题是环境岩土工程的一个重要分支。本文通过核贮置环境系统分析 ,提出了核环境岩土问题研究的 6种主要形式 ;对国内外研究现状进行了阐述 ;为研究防止核废料污染进入生物圈影响人居环境提供了有效方法依据 ,并对核废料贮置选址、设计具有重要理论和实际意义。     

环境中的铊及其健康效应

铊是一种稀有分散元素.近年来随着含铊矿产资源的开发,使较多的铊元素进入环境并在环境当中富集.铊是一种高毒性的物质,通过食物链进入生物圈,对生物体和人体健康产生毒害作用.由于铊对环境造成的影响具有明显的滞后作用,其潜在的危害和威胁远比近期影响严重得多,所以它将成为未来环境中的"化学定时炸弹".     

生物活体组织温度振荡机理的模拟实验研究

基于作者提出的理论详细研究了活体组织温度振荡行为的物理机制,建成了类似于生物传热系统的人工模拟装置,开展了一系列原理性验证实验,所得结论与理论预示和分析得到的结果较为吻合,因而揭示了生物活体组织温度振荡效应的热波机制,使得对这一重要的热生理现象有了新的发现和认识,为进一步从事相关研究奠定了基础。本文实验装置中所观察到的温度振荡现象在工程热物理领域内可能也系首次报道。     

The immune response of Drosophila

Drosophila mounts a potent host defence when challenged by various microorganisms. Analysis of this defence by molecular genetics has now provided a global picture of the mechanisms by which this insect senses infection, discriminates between various classes of microorganisms and induces the production of effector molecules, among which antimicrobial peptides are prominent. An unexpected result of these studies was the discovery that most of the genes involved in the Drosophila host defence are homologous or very similar to genes implicated in mammalian innate immune defences. Recent progress in research on Drosophila immune defence provides evidence for similarities and differences between Drosophila immune responses and mammalian innate immunity.     

A reduced estimate of the number of kilometre-sized near-Earth asteroids

Near-Earth asteroids are small (diameters < 10 km), rocky bodies with orbits that approach that of the Earth (they come within 1.3 AU of the Sun). Most have a chance of approximately 0.5% of colliding with the Earth in the next million years. The total number of such bodies with diameters > 1 km has been estimated to be in the range 1,000-2,000, which translates to an approximately 1% chance of a catastrophic collision with the Earth in the next millennium. These numbers are, however, poorly constrained because of the limitations of previous searches using photographic plates. (One kilometre is below the size of a body whose impact on the Earth would produce global effects.) Here we report an analysis of our survey for near-Earth asteroids that uses improved detection technologies. We find that the total number of asteroids with diameters > 1 km is about half the earlier estimates. At the current rate of discovery of near-Earth asteroids, 90% will probably have been detected within the next 20 years.