Geothermal convection through oceanic crust and sediments in the Indian ocean

Closely spaced heat flow surveys at four sites on the flanks of the Central Indian Ridge and the Southeast Indian Ridge delineate a pattern of oscillatory heat flow which can only result from cellular convection of oceanic bottom water through the oceanic crust and overlying sediment. These cells have a wavelength of 5 to 10 kilometers and are presently active in sea floor 18 x 10(6), 25 x 10(6), and 45 x 10(6) years old of the Crozet Basin and in sea floor 55 x 10(6) years old of the Madagascar Basin. The precise measurement of nonlinear temperature profiles makes it possible to calculate the conductive and convective heat transfer components through the sea floor. Even in the oldest sites, geothermal convection is still a major component of heat transfer through both the crust and sedimentary layers. These observations coupled with the results of earlier oceanwide geothermal studies indicate that more than one-third of the entire surface area of the world's ocean floor contains presently active geothermal convection that is cellular in plan form.     

Venting of carbon dioxide-rich fluid and hydrate formation in mid-okinawa trough backarc basin

Carbon dioxide-rich fluid bubbles, containing approximately 86 percent CO(2), 3 percent H(2)S, and 11 percent residual gas (CH(4) + H(2)), were observed to emerge from the sea floor at 1335- to 1550-m depth in the JADE hydrothermal field, mid-Okinawa Trough. Upon contact with seawater at 3.8 degrees C, gas hydrate immediately formed on the surface of the bubbles and these hydrates coalesced to form pipes standing on the sediments. Chemical composition and carbon, sulfur, and helium isotopic ratios indicate that the CO(2)-rich fluid was derived from the same magmatic source as dissolved gases in 320 degrees C hydrothermal solution emitted from a nearby black smoker chimney. The CO(2)-rich fluid phase may be separated by subsurface boiling of hydrothermal solutions or by leaching of CO(2)-rich fluid inclusion during posteruption interaction between pore water and volcanogenic sediments.     

Extending the sub-sea-floor biosphere

Sub-sea-floor sediments may contain two-thirds of Earth's total prokaryotic biomass. However, this has its basis in data extrapolation from ~500-meter to 4-kilometer depths, whereas the deepest documented prokaryotes are from only 842 meters. Here, we provide evidence for low concentrations of living prokaryotic cells in the deepest (1626 meters below the sea floor), oldest (111 million years old), and potentially hottest (~100 degrees C) marine sediments investigated. These Newfoundland margin sediments also have DNA sequences related to thermophilic and/or hyperthermophilic Archaea. These form two unique clusters within Pyrococcus and Thermococcus genera, suggesting unknown, uncultured groups are present in deep, hot, marine sediments (~54 degrees to 100 degrees C). Sequences of anaerobic methane-oxidizing Archaea were also present, suggesting a deep biosphere partly supported by methane. These findings demonstrate that the sub-sea-floor biosphere extends to at least 1600 meters below the sea floor and probably deeper, given an upper temperature limit for prokaryotic life of at least 113 degrees C and increasing thermogenic energy supply with depth.     

北京市地热资源开发利用状况

北京地区有丰富的低温地热能源,有开发潜力热储面积已达到2760km2,共分为10个地热田,其中最著名的是城区地热田和小汤山地热田。北京地区地热水中富含多种对人体有益成分,被直接用于采暖、洗浴、温室种植、养鱼、温泉疗养及休闲娱乐等,产生了巨大的环境、社会及经济效益。介绍了北京地区区域地质条件,分析了热储及地热水特征等,对北京地区的地热开发利用历史进行总结,并讨论了在地热直接应用过程中遇到的各种问题,以及影响地热资源可持续开发利用的相关因素。     

A high-efficiency power cycle in which hydrogen is compressed by absorption in metal hydrides

A high-efficiency power cycle is proposed in which molecular hydrogen gas is used as a working fluid in a regenerative closed Brayton cycle. The hydrogen gas is compressed by an absorption-desorption cycle on metal hydride (FeTiH(x)) beds. Low-temperature solar or geothermal heat (temperature about 100 degrees C) is used for the compression process, and high-temperature fossil fuel or nuclear heat (temperature about 700 degrees C) supplies the expansion work in the turbine. Typically, about 90 percent of the high-temperature heat input is converted to electricity, while about 3 kilowatts of low-temperature heat is required per kilowatt of electrical output.     

地热水资源开发引起的环境问题分析

论述地热水资源开发引起主要环境问题的成因和主要类型,包括地震、地面沉降、地热资源衰竭、地热水有害成分污染、空气污染、热污染等,同时提出相应的防治建议。     

Detection of overflow events in the shag rocks passage, scotia ridge

During an almost yearlong period of observations made with a current meter in the fracture zone between the Falkland Islands (Islas Malvinas) and South Georgia, several overflow events were recorded at a depth of 3000 meters carrying cold bottom water from the Scotia Sea into the Argentine Basin. The outflow bursts of Scotia Sea bottom water, a mixing product of Weddell Sea and eastern Pacific bottom water, were associated with typical speeds of more than 28 centimeters per second toward the northwest and characteristic temperatures below 0.6 degrees C. The maximum 24-hour average speed of 65 centimeters per second, together with a temperature of 0.29 degrees C, was encountered on 14 November 1980 at a water depth of 2973 meters, 35 meters above the sea floor.     

Fluids from aging ocean crust that support microbial life

Little is known about the potential for life in the vast, low-temperature (<100 degrees C) reservoir of fluids within mid-ocean ridge flank and ocean basin crust. Recently, an overpressured 300-meter-deep borehole was fitted with an experimental seal (CORK) delivering crustal fluids to the sea floor for discrete and large-volume sampling and characterization. Results demonstrate that the 65 degrees C fluids from 3.5-million-year-old ocean crust support microbial growth. Ribosomal RNA gene sequence data indicate the presence of diverse Bacteria and Archaea, including gene clones of varying degrees of relatedness to known nitrate reducers (with ammonia production), thermophilic sulfate reducers, and thermophilic fermentative heterotrophs, all consistent with fluid chemistry.     

基于GIS组件式地下热水管理信息系统设计

针对山西省地下热水资源开发及管理的现状和发展趋势,基于当前组件式GIS软件开发技术,构建了地下热水管理信息系统。阐述了地下热水管理信息系统的设计原则、开发方法和系统结构,介绍了该系统的信息查询、数据统计、地图输出和数据维护等主要功能,以及数据库的设计。     

深层地温传感器检定维护及数据对比分析

本文对谷城县国家基本气象观测站检定过程中发现的备份站深层地温套管内积水问题进行了处理,对深层地温温度传感器进行了周期检定,并对检定前后的深层地温数据进行了对比分析。结果表明,备份站深层地温80、320 cm套管积水主要是由于降水引起的,套管内积水会引发深层地温数据异常偏高,其中80 cm深层地温偏高13.21℃,320 cm深层地温偏高13.18℃。在对积水进行处理后,备份站深层地温恢复正常,两站深层地温数据一致性较好。同时,为了确保深层地温传感器的正常运行和观测数据的准确可靠,应按照规定的时间进行周期检定和维护工作,尤其要做好日常维护和降水后检查深层地温进水情况。     

Foraminifera and chlorophyll maximum: vertical distribution, seasonal succession, and paleoceanographic significance

Many planktonic foraminiferal species deposit their shells at the chlorophyll maximum zone, and it is the temperature range here that is relevant to oceanographic models which use ratios of oxygen-18 to oxygen-16 in fossil foraminifera and foraminiferal fossil assemblages to ascertain past climates. During periods of stratification of the upper water column, the temperature at the chlorophyll maximum may differ from the sea surface temperature by 10 degrees C in the western North Atlantic.     

河北省雄县RX10号地热水区域供暖系统的研究

本文以河北省雄县某地热井为例,分析了原有若干锅炉系统采暖改为地热采暖的设计方法、技术关键及三次供暖 (三次使用—地热水) 的可能性,并对地热水空间取暖进行了初步分析。     

渭河北岸断裂对咸阳地热田的影响

通过咸阳地热田实际已有地热地质资料及各地热井情况的研究分析,阐述了渭河北岸深大断裂在咸阳地热田中的重要地位和作用,论证了沿渭河北岸断裂附近开发地热资源的潜力远大于地热田内其他地区,可作为开展砂岩地层地热尾水回灌试验的首选区域。     

A transient rise in tropical sea surface temperature during the Paleocene-Eocene thermal maximum

The Paleocene-Eocene Thermal Maximum (PETM) has been attributed to a rapid rise in greenhouse gas levels. If so, warming should have occurred at all latitudes, although amplified toward the poles. Existing records reveal an increase in high-latitude sea surface temperatures (SSTs) (8 degrees to 10 degrees C) and in bottom water temperatures (4 degrees to 5 degrees C). To date, however, the character of the tropical SST response during this event remains unconstrained. Here we address this deficiency by using paired oxygen isotope and minor element (magnesium/calcium) ratios of planktonic foraminifera from a tropical Pacific core to estimate changes in SST. Using mixed-layer foraminifera, we found that the combined proxies imply a 4 degrees to 5 degrees C rise in Pacific SST during the PETM. These results would necessitate a rise in atmospheric pCO2 to levels three to four times as high as those estimated for the late Paleocene.     

中低温地热田的地热资源计算评价——以北京市小汤山地热田为例

我国的地热资源以中低温地热为主,其直接利用量居世界首位,但地热资源开发利用水平、研究程度和管理规范等方面尚有待提高。以北京市小汤山地热田为例,系统分析小汤山地热田的地质背景和地热地质条件,采用3种经典算法对该地区的地热资源进行资源评价。     

Life at high temperatures

Water environments with temperatures up to and above boiling are commonly found in association with geothermal activity. At temperatures above 60 degrees C, only bacteria are found. Bacteria with temperature optima over the range 65 degrees to 105 degrees C have been obtained in pure culture and are the object of many research projects. The upper temperature limit for life in liquid water has not yet been defined, but is likely to be somewhere between 110 degrees and 200 degrees C, since amino acids and nucleotides are destroyed at temperatures over 200 degrees C. Because bacteria capable of growth at high temperatures are found in many phylogenetic groups, it is likely that the ability to grow at high temperature had a polyphyletic origin. The macromolecules of these organisms are inherently more stable to heat than those of conventional organisms, but only small changes in sequence can lead to increases in thermostability. Because of their unique properties, thermophilic organisms and their enzymes have many potential biotechnological uses, and extensive research on industrial applications is under way.     

地热水开发利用的环境效应与可持续发展

本文论述了冀津地区地热水的特点及开发现状，开发利用地热水造成的环境问题，并提出了防治地热水污染的建议。     

Short-lived oxygen diffusion during hot, deep-seated meteoric alteration of anorthosite

Heterogeneous oxygen isotope compositions of plagioclase from the Boehls Butte anorthosite include some of the most oxygen-18-depleted values (to -16 per mil) reported for plagioclase in meta-igneous rocks and indicate high-temperature (T > 500 degrees C) isotopic exchange between plagioclase and nearly pristine meteoric fluid. Retrograde reaction-enhanced permeability assisted influx of meteoric-hydrothermal fluids into the deep-seated anorthosite. Isotopic gradients of about 14 per mil over 600 micrometers in single crystals require short-lived (about 10(4) years) diffusional exchange of oxygen and locally large effective water:rock ratios, followed by rapid loss of water and cessation of oxygen diffusion in the anorthosite.     

云南省汤池地热水中砷的健康风险评价

以美国环保总署推荐使用的污染场地健康风险评价方法为基础,首次结合砷的形态,对云南汤池地热水中砷对人群产生的健康风险进行了评价。结果表明,地热水中总砷含量为0.165 5 mg/L,其中As3+和As5+分别占64%和36%。砷的非致癌总风险指数为75.73,致癌总风险为1.10×10-2,可对人体健康产生极强的非致癌和致癌危害。饮用途径是产生风险的最主要的暴露途径,贡献量达90%以上。As3+产生的健康风险约为As5+的107倍,占总风险的99.1%。形态组成极大地影响着砷的健康风险。虽然,该研究的计算结果存在一定不确定性,但对将污染物形态组成纳入到健康风险评价中的研究具有重要参考意义。     

Freezing resistance in polar fishes

Arctic and antarctic fishes, living in contact with sea ice at -1.9 degrees C, have plasma equilibrium freezing points near -1.2 degrees C which are dependent on salt concentrations. These supercooled fishes have plasma protein concentrations much higher than other polar animals have, and the proteins impede ice propagation at temperatures down to -2 degrees C. Plasma protein concentration increases as environmental water temperature decreases.