The Influence of CO on the Carbon Isotopic Composition of CH_4 in Closed Pyrolysis Experiment With Coal     

刘全有  刘文汇 《中国地球化学学报》2004,23(4)

1IntroductionThecarbonisotopiccompositionofnaturalgasesisregardedasacontanttracerusedinthegeochemicalresearchofnaturalgases .Basedonthecarbonisotopiccomposition ,thegenetictypesofnaturalgasesarebasicallydividedtodeterminethematurationofnaturalgasesandmakegas sourcecorrelations (Stahl,1 973;StahlandCarey ,1 975;Stahletal.,1 977;James ,1 983;Schoell,1 983,1 988;DaiJinxingetal.,1 992 ;FuJiamoetal.,1 992 ;XuYongchang ,1 994 ) .Theformationofnaturalgasescouldbededucedintermsofcarbonisotopicvar…  相似文献   

石油污染对冻土热传导的影响     

Zhuravlev Igor Igorevich 《冰川冻土》2004,26(Z1):128-132

Complex experimental research of thermal properties of oil-contaminated frozen soils was carried out. On the basis of the obtained results the influence of the various factors connected with oil pollution on heat transfer in frozen soils was analyzed. And the model of heat transfer in frozen soils was offered.  相似文献   

多年冻土地区建筑物地基的热稳定性技术   总被引：1，自引：0，他引：1  

Refik M. Bayasan  Anatoly G. Korotchenko 《冰川冻土》2004,26(Z1):201-205

Thermal stabilization of soils (including freezing of thawed soils and cooling of permafrost) is known to be the effective method providing stable support for buildings and structures in cold regions.Seasonal thermo-stabilizers (STS) are mainly used in construction. The predicted climate warming because of natural and man-caused factors determines wide application of STS in permafrost regions. A STS transfers heat from its underground part (evaporator) to the aerial part (condenser) owing to natural temperature difference between them during a cold season. We have been working out and manufacturing different types of two-phase, vapor-liquid STS. Aluminum alloys are used in our STS to prevent corrosion and to increase their efficiency. They are successfully used in the northern regions of Western Siberia, in particular, at the railway Obskaya Bovanenkovo. The paper presents some technical parameters of new STS, the results of their experimental study and computer simulation, as well as experience features.  相似文献   

多年冻土区路桥过渡段的一种新结构     

刘建坤  鲍维猛  黎明  葛建军 《冰川冻土》2004,26(Z1):210-214

The design of roadbed-abutment transition part is always a challenging problem in transportation engineering, especially in permafrost distribution zone. A new type of roadbed-abutment transition part on permafrost was presented, and long-term observation was conducted for the deformation and the thermal regime of a roadbed-abutment transition part in the constructing Qinghai-Tibet Railway. In this paper, a new structure was presented and the observed settlements both in the subgrade and the base and its dependency with the thermal regime (permafrost table) were analyzed. In conclusion the roadbed-a-butment transition method for permafrost distribution zone was evaluated.  相似文献   

Evidence for freeze–thaw events and their implications for rock weathering in northern Canada     

Kevin Hall 《地球表面变化过程与地形》2004,29(1):43-57

Discussions regarding weathering in cold environments generally centre on mechanical processes and on the freeze–thaw mechanism in particular. Despite the almost ubiquitous assumption of freeze–thaw weathering, unequivocal proof of interstitial rock water actually freezing and thawing is singularly lacking. Equally, many studies have used the crossing of 0 °C, or values close to that, as the basis for determining the number of ‘freeze–thaw events’. In order to assess the weathering regime at a site in northern Canada, temperatures were collected at the surface, 1 cm and 3 cm depth for sets of paving bricks, with exposures both vertical and at 45°, orientated to the four cardinal directions. Temperature data were collected at 1 min intervals for 1 year. These data provide unequivocal proof for the occurrence of the freezing and thawing of water on and within the rock (freeze–thaw events). The freeze event is evidenced by the exotherm associated with the release of latent heat as the water actually freezes. This is thought to be the ?rst record of such events from a ?eld situation. More signi?cantly, it was found that the temperature at which freezing occurred varied signi?cantly through the year and that on occasion the 1 cm depth froze prior to the rock surface. The change in freeze temperature is thought to be due to the chemical weathering of the material (coupled with on‐going salt inputs via the melting of snowfall), which, it is shown, could occur throughout the winter despite air temperatures down to ?30 °C. This ?nding regarding chemical weathering is also considered to be highly signi?cant. A number of thermal stress events were also recorded, suggesting that rock weathering in cold regions is a synergistic combination of various chemical and mechanical weathering mechanisms. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Analysis of crack movements observed in an alpine bedrock cliff     

Mamoru Ishikawa  Yoshimasa Kurashige  Kazuomi Hirakawa 《地球表面变化过程与地形》2004,29(7):883-891

Crack widths and rock temperatures were monitored on an andestic bedrock cliff in the summit area of the Daisetsu Mountains, Hokkaido, northern Japan. Sequential data recorded the gradual widening of a crack to the point of critical crack extension, which resulted in catastrophic rock breakage. The data indicate that a combination of liquid water in?ltration into crack tip and subsequent freezing is the most signi?cant factor contributing to critical crack extension. The recorded sub‐critical crack movements involved a number of minor crack extensions and contractions, the timing of which correlates well with the magnitude of the reconstructed thermal stresses at the crack tip derived from thermal deformation of the plate‐shaped rock fragment. Larger crack extensions occurred when stress at the crack tip exceeded a threshold value, possibly re?ecting the control of rock fracture mechanics by which cracks are thought to propagate when the stress intensity factor at the crack tip exceeds the threshold values for stress corrosion cracking and the fracture toughness of the material. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

用远场辐射场反演云闪放电参数   总被引：2，自引：0，他引：2  

祝宝友  陶善昌  马明  吕伟涛 《气象学报》2004,62(4):498-503

用地面电磁场遥感闪电放电参数无论是在实际应用还是理论研究中都具有重要意义。文中基于电流传输线模式 ,提出了一种用单站远场VLF/LF辐射场反演云内放电参数的简便方法。当传输线电流从底部传播到顶部的时间只有几微秒时 ,整个传输线的VLF/LF辐射可以近似成偶极子辐射 ,即远场辐射场与电流的时间变化率和传输线长度的乘积成正比。因此 ,对远场辐射场做时间积分就能获得完整的电流矩波形 (上升沿有所加宽 ) ,而且传输线模式中的重要参数 ,电流从底部传播到顶端经历的时间 ,也可以近似地用辐射场时间积分幅度与辐射场幅度之比来估计。这一方法具有估计云闪双极性大脉冲辐射过程的放电参数的潜力。  相似文献   

镇旬铅锌矿田热水沉积硅岩研究   总被引：4，自引：0，他引：4  

侯满堂  臧世权  李新林 《陕西地质》2004,22(1):45-54

从镇(安)旬(阳)铅锌矿田热水沉积硅岩的产状、形态、岩石结构、构造、矿物成分、化学成分、微量元素、稀土元素、硫同位素、氧同位素等研究表明，本区硅岩具有以热液为主兼有生物和正常沉积的特征，并非典型热水沉积岩。  相似文献   

三峡大坝建成后长江输沙量的减少及其对长江三角洲的影响   总被引：3，自引：1，他引：3  

李从先  杨守业  范代读  赵娟 《第四纪研究》2004,24(4):495-500

三峡大坝建成之后,大量泥沙滞留于库区,出库泥沙量减少,坝下河床冲刷而提供相当数量的泥沙,支流湖泊供沙也发生变化,这将使进入河口地区的泥沙有所减少。三峡大坝以上长江干流和支流建设新的大坝,南水北调、封山育林、退耕还林以及减少水土流失都将进一步减少长江进入河口地区的泥沙。由此估计,三峡大坝建成后的百年内长江输入河口地区的泥沙约为2.0×10⁸～2.5×10⁸t/a;冰后期长江三角洲形成和发育期间的长江年均输沙量为1.84×10⁸～2.28×10⁸t。二者的数值相当接近,然而与近50年的观测(4.33×10⁸t/a)相差甚远,长江流域的气候变化和人类活动可能是造成这一现象的原因。文章着重说明中国和长江上游人口的增长、种植作物的改变可能是水土流失、长江泥沙量增长的主要原因。  相似文献   

Crustal Growth by Magmatic Accretion Constrained by Metamorphic P-T Paths and Thermal Models of the Kohistan Arc, NW Himalayas   总被引：2，自引：0，他引：2  

YOSHINO  TAKASHI; OKUDAIRA  TAKAMOTO 《Journal of Petrology》2004,45(11):2287-2302

Magmatic accretion is potentially an important mechanism inthe growth of the continental crust and the formation of granulites.In this study, the thermal evolution of a magmatic arc in responseto magmatic accretion is modeled using numerical solutions ofthe one-dimensional heat conduction equation. The initial andboundary conditions used in the model are constrained by geologicalobservations made in the Kohistan area, NW Himalayas. Takingconsideration of the preferred intrusion locations for basalticmagmas, we consider two plausible modes of magmatic accretion:the first involves the repeated intrusion of basalt at mid-crustaldepths (‘intraplate model’), and the second evaluatesthe simultaneous intrusion of basalt and picrite at mid-crustaldepths and the base of the crust respectively (‘double-platemodel’). The results of the double-plate model accountfor both the inferred metamorphic P–T paths of the Kohistanmafic granulites and the continental geotherm determined frompeak P–T conditions observed for granulite terranes. Thedouble-plate model may be applicable as a key growth processfor the production of thick mafic lower crust in magmatic arcs. KEY WORDS: thermal model; magmatic underplating; P–T path; granulite; lower crust  相似文献