Blood function in the hydrothermal vent vestimentiferan tube worm

Extracellular hemoglobin in the whole blood of Riftia pachyptila has a high oxygen affinity (P50 = 1.8 millimeters of mercury at 3 degrees C), a moderate decrease in oxygen affinity at higher temperatures (P50 = 2.7 millimeters of mercury at 14 degrees C), a small effect of carbon dioxide on oxygen affinity (Delta log P50/Delta pH =-0.12), and a high oxygen carrying capacity (up to 11 milliliters of oxygen per 100 milliliters of blood). These characteristics are compatible with the high oxygen demand of chemoautotrophic metabolism in the variable vent environment.     

Biological communities at the Florida escarpment resemble hydrothermal vent taxa

Dense biological communities of large epifaunal taxa similar to those found along ridge crest vents at the East Pacific Rise were discovered in the abyssal Gulf of Mexico. These assemblages occur on a passive continental margin at the base of the Florida Escarpment, the interface between the relatively impermeable hemipelagic clays of the distal Mississippi Fan and the jointed Cretaceous limestone of the Florida Platform. The fauna apparently is nourished by sulfide rich hypersaline waters seeping out at near ambient temperatures onto the sea floor.     

30,000 years of hydrothermal activity at the lost city vent field

Strontium, carbon, and oxygen isotope data and radiocarbon ages document at least 30,000 years of hydrothermal activity driven by serpentinization reactions at Lost City. Serpentinization beneath this off-axis field is estimated to occur at a minimum rate of 1.2 x 10(-4) cubic kilometers per year. The access of seawater to relatively cool, fresh peridotite, coupled with faulting, volumetric expansion, and mass wasting processes, are crucial to sustain such systems. The amount of heat produced by serpentinization of peridotite massifs, typical of slow and ultraslow spreading environments, has the potential to drive Lost City-type systems for hundreds of thousands, possibly millions, of years.     

Functional characteristics of the blood of the deep-sea hydrothermal vent brachyuran crab

Hemocyanin in the whole blood of the hydrothermal vent brachyuran crab, Bythograea thermydron, has a moderate oxygen affinity (P(50) = 6.6 millimeters of mercury at 2.6 degrees C; pH 7.5), which unlike that of other hemocyanins is independent of temperature over the range 2 degrees to 30 degrees C; carbon dioxide and pH have independent effects on the oxygen affinity of this pigment. The pH effect on affinity is moderate (Deltalog P(50)/DeltapH = -0.34), whereas increased carbon dioxide, which can act both directly and by changing pH, has a much larger effect (Deltalog P(50)/DeltapH = -0.81). This blood has a moderately high degree of cooperativity (Hill cooperativity coefficient, n, was 2.8) and a large oxygen-carrying capacity for a crustacean (4.5 milliliters of oxygen per 100 milliliters of blood). These properties characterize an oxygen transport system whose function appears to be largely independent of the wide range of environmental conditions encountered around the vents.     

Stable carbon isotopic evidence for carbon limitation in hydrothermal vent vestimentiferans

Stable carbon isotope composition (delta(13)C values) can be used to evaluate an animal's source of nutritional carbon. Most animals with chemoautotrophic endosymbionts have quite negative tissue delta(13)C values due to discrimination against (13)C associated with chemoautotrophic assimilation of inorganic carbon. However, the delta(13)C values of hydrothermal vent (HTV) vestimentiferans are significantly higher than the values reported for non-HTV vestimentiferans or other invertebrates with chemoautotrophic endosymbionts. Tissue delta(13)C values of two species of HTV vestimentiferans increase with increasing size of the animals. This relation supports the hypothesis that the relatively high delta(13)C values are the result of inorganic carbon limitation during carbon fixation. A more favorable relation between gas exchange and carbon fixation in the smaller individuals is expected, due to differences in the geometric scaling of gas-exchange surfaces and trophosome volume.     

Carbon-13 depletion in a hydrothermal vent mussel: suggestion of a chemosynthetic food source

Tissues of a mytilid mussel from the Clambake I hydrothermal vent in the Galápagos Rift zone are strikingly depleted in carbon-13 relative to the tissues of other marine organisms. The stable carbon isotope composition of this mussel suggests that chemoautotrophic bacteria present in the hydrothermal waters are a major food source for filter-feeding organisms in this abyssal environment.     

In situ measurements of chemical distributions in a deep-sea hydrothermal vent field

Large changes in the concentration of sulfide around a hydrothermal vent in the Galápagos Rift provide direct evidence for the consumption of sulfide by the organisms of the vent community. These changes were detected with a new chemical analyzer capable of measuring silicate, sulfide, oxygen, and temperature on the sea floor at depths of 2500 meters. More than 10,000 measurements showed systematic variations in the sulfide and oxygen concentrations due to biogenic oxidation of sulfide in the hydrothermal solutions. Silicate concentration was highly correlated with temperature, but different trends were observed at different locations.     

Membrane lipid from deep-sea hydrothermal vent methanogen: a new macrocyclic glycerol diether

The membrane lipid of a new deep-sea hydrothermal vent methanogen, Methanococcus jannaschii, has been structurally characterized. The hydrolyzed polar lipid of this archaebacterium is primarily (95 percent) a macrocyclic glycerol diether, which has not been described previously. The structure was elucidated by a combination of chemical and spectroscopic techniques. An initial survey of selected methanogens failed to indicate the presence of this membrane lipid in any microorganism other than Methanococcus jannaschii.     

Clams As recorders of ocean ridge volcanism and hydrothermal vent field activity

The clam Calyptogena magnifica lives at abyssal depths in association with hydrothermal venting on midocean ridges. Analysis of strontium/calcium ratios in C. magnifica shells provides a temperature proxy with submonthly time resolution. A 21-year strontium/calcium record of two clams from 9 degrees50'N on the East Pacific Rise captures the known 1991 and 1992 eruptive events, documents several additional events between 1992 and 1996, and demonstrates the absence of major hydrothermal episodes during the period 1974 to 1991. These clam archives can increase our understanding of the thermal and chemical history of midocean ridge hydrothermal and volcanic activity on decadal time scales.     

Fossils of hydrothermal vent worms from cretaceous sulfide ores of the samail ophiolite, oman

Fossil worm tubes of Cretaceous age preserved in the Bayda massive sulfide deposit of the Samail ophiolite, Oman, are apparently the first documented examples of fossils embedded in massive sulfide deposits from the geologic record. The geologic setting of the Bayda deposit and the distinctive mineralogic and textural features of the fossiliferous samples suggest that the Bayda sulfide deposit and fossil fauna are remnants of a Cretaceous sea-floor hydrothermal vent similar to modern hot springs on the East Pacific Rise and the Juan de Fuca Ridge.     

一株深海热液口超嗜热古菌的分类鉴定及高温酶活性研究

对一株分离自深海热液口古菌HJ21进行了分类鉴定及高温酶活性的研究.该菌株是极端嗜热的厌氧球菌,直径为1.0～1.2 靘.菌株最适生长温度88 ℃;菌株生长pH为5.0～9.0,最适pH为6.5～7.0;菌株生长NaCl质量浓度为10～50 g·L-1,最适为20 g·L-1.根据其形态特征、生理生化特性以及16S rRNA基因序列分析结果,确定HJ21菌株为热球菌属(Thermococcus).该菌株能产生高热稳定的高温α-淀粉酶、普鲁兰酶、α-葡萄糖苷酶和蛋白酶,这些酶的最适作用温度分别为95、95、100和100 ℃,α-淀粉酶、普鲁兰酶和α-葡萄糖苷酶在90 ℃的半衰期分别为5、5和2 h;蛋白酶在100 ℃保温2.5 h后仍具有84%的酶活性.     

Blood pressure control--special role of the kidneys and body fluids

The arterial pressure of the adult human rarely deviates from normal by more than 10 to 15 percent during each day. To achieve such constancy, the body has a network of pressure control systems. Several are based on neural receptors that respond within seconds to help correct any abnormal pressure. The activities of these systems are followed within minutes by activation of hormonal controllers. Within hours or days, a kidney pressure control system is induced that increases body fluid volume when the pressure falls (or decreases the volume when the pressure rises). This kidney-fluid system is the dominant method of establishing long-term pressure control.     

Hydrocarbons of blue-green algae: geochemical signfficance

The hydrocarbon compositions of 11 species of blue-green algae are simple and qualitatively similar. Three marine coccoids contain only monoenoic and dienoic C(19) hydrocarbons. Hydrocarbons of the remaining eight species are C(15) to C(18). Hydrocarbons of higher molecular weight (C(20) or more) were not detected. Blue-green algae do not appear to be the source material for the longchain (greater than 20 carbons) hydrocarbons found in ancient sediments.     

Diffusion Coefficients of Hydrocarbons in Water: Method for Measuring

A modification of the capillary-cell method of measuring diffusion coefficients has been applied in studying the diffusion of paraffin hydrocarbons in water. Measurements on ethane, propane, and normal butane indicate that diffusion coefficients can be obtained with a precision of 1 to 2 percent.     

A serpentinite-hosted ecosystem: the Lost City hydrothermal field

The serpentinite-hosted Lost City hydrothermal field is a remarkable submarine ecosystem in which geological, chemical, and biological processes are intimately interlinked. Reactions between seawater and upper mantle peridotite produce methane- and hydrogen-rich fluids, with temperatures ranging from <40 degrees to 90 degrees C at pH 9 to 11, and carbonate chimneys 30 to 60 meters tall. A low diversity of microorganisms related to methane-cycling Archaea thrive in the warm porous interiors of the edifices. Macrofaunal communities show a degree of species diversity at least as high as that of black smoker vent sites along the Mid-Atlantic Ridge, but they lack the high biomasses of chemosynthetic organisms that are typical of volcanically driven systems.     

一步水热合成ZnO/水热炭复合材料及其性能表征

为了利用林业剩余物水热炭作光催化剂载体,以(CH₃COO)₂Zn·2H₂O和氨水为起始物,以综纤维素基水热炭为基体,采用一步水热合成法制备ZnO/水热炭复合材料。采用X射线衍射仪、扫描电子显微镜对复合材料的晶相结构、表观形貌等进行表征,并以亚甲基蓝为模型污染物测试了复合材料的光催化性能。研究结果表明:在实验条件下可以制备出ZnO/水热炭复合材料,材料中ZnO为六方纤锌矿结构,随水热炭添加量增加,ZnO尺寸有明显的减小,但当水热炭达到24.6%时,ZnO由一维取向的棒状转而呈现片状。光催化性能测试表明:ZnO/水热炭复合材料的光催化性能较纯ZnO有明显提高,其中水热炭为19.7%时,光催化性能最佳,降解效率达到83.1%。动力学分析表明:复合材料对亚甲基蓝的光催化降解过程符合一级动力学模型。      

土壤中多环芳烃污染的研究进展

简要地论述了PAHs在土壤中的吸附、分布情况;对土壤中PAHs的前处理技术、测定方法分别进行了归纳和对比,并对土壤中PAHs的微生物降解的研究进展进行了综述.     

西气东输站场放空天然气回收需求与工艺

天然气长输管道增压站和分输站放空主要包括紧急抢修放空和计划性放空,前者具有随机性,单次放空量大,不具备回收的技术条件,后者主要指分离器排污放空和压缩机定期检修放空,具有较强的计划性和一定的规律性,具有良好的回收基础条件和回收价值。西气东输管道站场压缩机检修和分离器排污两项放空量之和占总放空量的50%以上,对放空天然气进行回收是可行和必要的。为此,设计了一套以CNG压缩机为核心的站场放空天然气回收工艺系统,可对站场因设备维修、排污等产生的放空天然气进行回收并重新注入上游管道、下游管道或分输管道,达到节能减排的目的。     

多环芳烃微生物降解的研究进展

多环芳烃(PAHs)是一类普遍存在于环境中的难降解的有机污染物。对多环芳烃的来源、分布、危害、处理方法等进行了综述,并对该领域的研究方向进行了展望。