21世纪能源与环境的前沿问题——天然气水合物   总被引：6，自引：1，他引：6  

孙成权  朱岳年 《地球科学进展》1994,9(6):49-52

天然气水合物资源极为丰富。据国外专家估算，水合物中的天然气总资源超过了包括煤炭、石油与常规天然气在内的所有已知可燃矿产的储量。天然气水合物层是油气聚集的极好盖层，可以作为勘探油气藏的标志。天然气水合物还是影响全球气候变化的重要温室气体之一的甲烷的重要源和汇。因此，进行天然气水合物研究对开拓２１世纪能源、完善油气成藏理论、解决天然气工业生产和输送过程的管进堵塞问题，以及探讨其与全球气候变化的关系问题均有重大意义。目前应开展的研究内容与重点课题包括：天然气水合物的成因机制与油气成藏演化规律；分布规律及有利蕴藏地区；物化特性及其生成与消除的方法；天然气水合物与全球气候变化的关系等。  相似文献   

Comparison of taxon calibrations,modern analogue techniques,and forest-stand simulation models for the quantitative reconstruction of past vegetation: A critique     

Allen M. Solomon 《地球表面变化过程与地形》1986,11(6):681-685

Taxon calibrations based on eastern North America or on the southeastern United States alone suggest a different forest composition from that based on Wisconsin/Michigan, which is argued as preferable. Questions are raised about how well comparison with modern analogues distinguishes forest characteristics. The simulation model used by Delcourt and Delcourt is thought to be inappropriate, partly because it is constrained by faulty climatic data. Models are seen as complementary to other techniques rather than as an alternative methodology.  相似文献   

天然气运移的气体同位素地球化学示踪   总被引：16，自引：0，他引：16  

张同伟  陈践发 《沉积学报》1995,13(2):70-76

本文通过鄂尔多斯等含油气盆地内岩石酸解烃、罐顶气和同源多产层天然气碳同位素组成的变化，从实例剖析出发，探讨了天然气运移时气体同位素组成的变化及其对天然气运移的示踪。天然气在通过沉积地层中孔隙系统和微裂隙运移时，天然气中的甲烷碳同位素会发生一定的分馏，而乙烷以上重烃碳同位素几乎不发生分馏；在天然气层所在深度，罐顶气甲烷碳同位素组成与天然气一致，在天然气层附近，罐顶气甲烷碳同位素则明显偏离了热演化趋势线；烃源岩酸解烃与其同源的天然气重烃碳同位素组成具有较好的一致性和可比性。由此，可利用气体组分碳同位素的上述变化特征，追索天然气的运移作用。  相似文献   

湖南省桂东县自然资源特征及其可持续发展研究     

谢玉华  吴甫成  郭建平  熊建安 《热带地理》2007,27(6):548-552

湖南省桂东县处于边远山区,经济发展水平低,为国家级贫困县。但其自然资源丰富,生态环境质量良好,旅游资源独具特色。通过对边远山区县资源环境特点和经济发展现状的分析,提出了促进地区可持续发展的建议:调整产业结构,在发展超级稻和优质稻基础上,发展具有地方特色的药、菜、茶、果、烟,外加楠竹和园艺的种植业,发展以牛、羊等草食性牲畜为主的养殖业;发展小水电和以电力为基础的电化工业及农产品加工业;发展红色旅游和休闲度假相结合的生态旅游业;加强生态环境保护力度,以促进桂东区域经济的可持续发展。  相似文献   

How can the epikarst zone influence the karst aquifer hydraulic behaviour?   总被引：3，自引：0，他引：3  

Branka Trček 《Environmental Geology》2007,51(5):761-765

The role of an epikarst zone in the karst aquifer hydraulic behaviour was brought into focus in our studies referring to the catchment area of the Hubelj spring (SW Slovenia). This study points out the significance of effects of the fast preferential flow—epiflow, which is the main factor controlling solute/contaminant transport towards the aquifer saturated zone. The so-called epikarstic hypothesis is verified on the basis of the most significant research results that are supported by the most important findings from the literature.  相似文献   

Paleolimnological reconstructions of Rouyn-Noranda lakes within the zone of influence of the Horne Smelter,Québec,Canada     

Aruna S. Dixit  S. Alpay  Sushil S. Dixit  John P. Smol 《Journal of Paleolimnology》2007,38(2):209-226

Diatoms were identified and enumerated from a surface sediment calibration set of 50 lakes in northwestern Québec. The relationship between species composition and environmental variables was examined using canonical correspondence analysis (CCA). Forward selection and Monte Carlo permutation tests in CCA indicated that diatom species distributions in the data set are most strongly correlated to lakewater pH. A strong (r ² _boot = 0.83) weighted averaging calibration model, that includes bootstrapped error estimates, was developed for inferring past lakewater pH. Using this model, temporal changes in pH were reconstructed for two kettle lakes, Lac de la Pépinière and Lac Perron. Based on limnological data, both the study lakes were expected to have recently acidified due to increased acidic precipitation and increases in anthropogenic metal loading. However, our long-term pH inference data indicate that these lakes were naturally acidic during pre-industrial times. Nonetheless, the rate of acidification, particularly in Lac de la Pépinière, has accelerated in the last ∼75 years. These long-term pH records developed for the dilute lakes in northwestern Québec suggest that the region has received increased atmospheric pollutants from the nearby Horne smelter in Rouyn-Noranda. The pH inference profiles are markedly different from many other paleolimnological studies in acid-sensitive regions of Canada that have become acidic primarily as a result of industrial activities. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.  相似文献   

Thermal surface characteristics of coal fires 1 results of in-situ measurements     

Jianzhong Zhang  Claudia Kuenzer   《Journal of Applied Geophysics》2007,63(3-4):117-134

Natural underground coal fires are fires in coal seams occurring subsurface. The fires are ignited through a process named spontaneous combustion, which occurs based on a natural reaction but is usually triggered through human interaction. Coal mining activities expose coal to the air. This leads to the exothermal oxidation of the carbon in the coal with the air's oxygen to CO₂ and – under certain circumstances – to spontaneous combustion. Coal fires occur in many countries world wide – however, currently the Chinese coal mining industry faces the biggest problems with coal fires. Coal fires destroy the valuable resource coal and furthermore lead to many environmental degradation phenomena such as the deterioration of surrounding vegetation, land subsidence and the emission of toxic gasses (CO, N₂O). They additionally contribute to the emission of green house relevant gasses such as CO₂ and CH₄ to the atmosphere.In this paper we present thermal characteristics of coal fires as measured in-situ during a field campaign to the Wuda coal fire area in south-central Inner Mongolia, China. Thermal characteristics include temperature anomaly measurements at the surface, spatial surface temperature profiles of fire areas and unaffected background areas, diurnal temperature profiles, and temperature measurements inside of coal fire induced cracks in the overlying bedrock. For all the measurements the effects of uneven solar heating through influences of slope and aspect are considered.Our findings show that coal fires result in strong or subtle thermal surface anomalies. Especially the latter can easily be influenced by heating of the surrounding background material through solar influences. Temperature variation of background rocks with different albedo, slope, aspect or vegetation cover can substantially influence the detectability of thermal anomalies. In the worst case coal fire related thermal anomalies can be completely masked by solar patterns during the daytime. Thus, night-time analysis is the most suitable for thermal anomaly mapping of underground coal fires, although this is not always feasible. The heat of underground coal fires only progresses very slowly through conduction in the rock material. Anomalies of coal fires completely covered by solid unfractured bedrock are very weak and were only measured during the night. The thermal pattern of underground coal fires manifested on the surface during the daytime is thus the pattern of cracks and vents, which occur due to the volume loss underground and which support radiation and convective energy transport of hot gasses. Inside coal fire temperatures can hardly be measured and can only be recorded if the glowing coal is exposed through a wider crack in the overlaying bedrock. Direct coal fire temperatures measured ranged between 233 °C and 854 °C. The results presented can substantially support the planning of thermal mapping campaigns, analyses of coal fire thermal anomalies in remotely sensed data, and can provide initial and boundary conditions for coal fire related numerical modeling.In a second paper named “Thermal Characteristics of Coal Fires 2: results of measurements on simulated coal fires” [Zhang J., Kuenzer C., Tetzlaff A., Oettl D., Zhukov B., Wagner W., 2007. Thermal Characteristics of Coal Fires 2: Result of measurements on simulated coal fires. Accepted for publication at Journal of Applied Geophysics. doi:10.1016/j.jappgeo.2007.08.003] we report about thermal characteristics of simulated coal fires simulated under simplified conditions. The simulated set up allowed us to measure even more parameters under undisturbed conditions — especially inside fire temperatures. Furthermore we could demonstrate the differences between open surface coal fires and covered underground coal fires. Thermal signals of coal fires in near range thermal remotely sensed imagery from an observing tower and from an airplane are presented and discussed.  相似文献   

某隔震结构动力特性的理论分析与脉动测试   总被引：1，自引：1，他引：1  

贾洪  徐茂义  闫维明  李振宝 《震灾防御技术》2007,2(4):384-390

本文针对国内最大单体隔震建筑建立了SAP2000三维分析模型,并进行了动力特性的理论分析;现场对实际建筑进行了平移振动、扭转振动、垂直振动和平面内弯曲4个方面的脉动测试。利用工程振动反演理论分析了该结构的固有频率、振型、阻尼等动力特性,将实测结构动力特性与理论分析结果进行比较,详细分析实测结果与理论结果差别的原因,并据此对理论模型进行修正,为今后类似结构的设计积累了资料。  相似文献   

Policy and practice in karst landscape protection: Bohol, the Philippines     

Peter B. Urich  Michael J. Day  & Fiona Lynagh 《The Geographical journal》2001,167(4):305-323

The karst landscape in the interior of the Philippines' Bohol Province represents one of the world's premier kegelkarst (cone karst) environments. Government efforts to protect some of this karst, exemplified by the establishment of the Rajah Sikatuna National Park and the Chocolate Hills Natural Monument, have proven to be significant catalysts of social conflict. In Bohol there is a long history of traditional land tenure, which has recently been supplanted by a Westernized model. Protected area establishment is a response to deforestation, agricultural exploitation and uncontrolled quarrying. However, the imposition of protective legislation to prevent further degradation has disenfranchized and marginalized many local farmers and residents. The conflict between the obligation of the State to ensure environmental protection and the perceived property rights of landowners and farmers has provoked an escalation in civil unrest and armed conflict.  相似文献   

Application of the photoacoustic method for characterization of natural galena (PbS)     

P. M. Nikolić  S. Ðurić  D. M. Todorović  D. Vasiljević-Radović  V. Blagojević  P. Mihajlović  J. Elazar  K. T. Radulović  A. I. Bojičić  D. Urošević 《Physics and Chemistry of Minerals》2001,28(1):44-51

Electron transport properties of single crystal and polycrystalline natural mineral galena (PbS) samples from the Trep?a mine, Yugoslavia, were determined using the photoacoustic frequency transmission technique. Their thermal diffusivity (D _T≈0.16 × 10^?5 m² s^?1), the coefficient of diffusion (D between 0.15×10^?2 0.16×10^?2 m² s^?1) and lifetime of the excess carrier (τ≈35 μs and the front and rear recombination velocity (s _g≈65.5 m s^?1 and s _b≈66.4 m s^?1, respectively), were calculated by comparing the experimental results and the theoretical photoacoustic amplitude and phase signals. The lattice parameter obtained by X-ray work was a?=5.936?Å. The free carrier concentration of these single-crystal samples was measured using the Hall method (N?=?3×10¹⁸ cm^?3). Measurements of the optical reflectivity of the same samples, as a function of wavelength, in the infrared and far infrared ranges, were performed. In the far infrared range a free electron plasma frequency was observed and numerically analyzed, using the least-squares fitting procedure. The values of optical parameters were calculated and the value of the free carrier concentration obtained by the Hall method was confirmed.  相似文献