准噶尔盆地中部III 区块原油中25-降藿烷分布特征与成因意义

通过对准噶尔盆地中部Ш区块原油或油砂抽提物的饱和烃气相色谱-质谱分析,研究了原油或油砂抽提物中25-降藿烷的分布规律.结果表明,不同井区或同一口井不同深度(层位)的原油25-降藿烷的相对含量存在比较明显的差别,表明其所遭受的生物降解程度有所差异,沿构造带从南到北,同一油层中原油的生物降解程度增强,比如位于构造北部(构造部位相对较高)的永1井、永3井侏罗系原油25-降藿烷丰度较高,表明生物降解比较明显,而位于南部(构造低部位)的永6井白垩系和侏罗系油层中的原油均无明显的生物降解现象;同一口井随深度增大生物降解作用将弱,如永2井浅部白垩系油层的原油降解较严重,而深部西山窑组的原油降解作用则不明显.根据原油生物降解的特征,结合车-莫古隆起调整对研究区油气成藏的影响,讨论了原油生物降解差异分布的成因机制.     

应用探地雷达探测活动断层

在浅覆盖区采用探地雷达探测地震活动断层。通过实验确定出最佳的采集参数和数据处理流程,在雷达剖面上,能够清晰地显示出断层上部的形态特征、上断点埋深和岩土分层。结合钻孔资料,利用雷达剖面上对第四系覆盖的分层结果和上断点所在的层位可以分析和评价断层的活动性。     

Climate changing characteristics of Zhangye City in Heihe River basin during 1968–2005

At present, researches on climate change of the Heihe River basin mainly focus on the relationship between basin climate change and regional water resources, regional desertification and dynamic climatic seasons of sandstorm, but less on climate change of oasis region, where there are more intense and frequent human activities. Based on data of precipitation, temperature, strong wind and dust events frequencies obtained from the six meteorological stations of Zhangye region in Heihe River basin, the features of climate change during 1968–2005 were carefully studied. Results show that the regional temperature rise rate exceeded the average level of China. The annual precipitation changed a little, but the precipitation had a slowly increasing trend in spring and winter. Frequencies of strong wind and sandstorm days show obviously descending trends, which had a close correlation with the regional temperature rise and the precipitation increase in spring and winter. Meanwhile, further human economic activities and exploitations to the oasis in the inland valley of arid regions also affected the climate change of this region, which has a sensitive and fragile eco-environment. __________ Translated from Journal of Desert Research, 2007, 27(6): 1048–1054 [译自: 中国沙漠]     

危化品泄漏扩散预测模型与GIS集成及其在应急决策中的应用研究

在研究和分析危化品泄漏扩散预测模型的基础上,将危化品泄漏扩散快速预测模型在应急平台中与GIS系统进行集成,实现危化品泄漏扩散过程在地理场景中的动态仿真推演,在模型库、预案库的支持下,利用空间分析技术辅助应急决策,生成应急指挥决策方案。     

About the specification of erosion flux for soft stratified cohesive sediments

The present paper deals with the specification of bed erosion flux that accounts for the effects of sediment-induced stratification in the water column. Owing to difficulties in measuring the bed shear stress _b and the erosive shear strength _s, we suggest a series of methods that combine laboratory and numerical experiments. A simplified turbulent transport model that includes these effects helps to quantify _b and _s. Focusing on soft stratified beds, the present study considers erosion rate formulas of the form =_f exp {[T_b-T_s]} where is a model constant (=1 for Gularte's (1978) formula and =1/2 for Parchure's (1984) formula). First, the bed erosive strength profile _s(Z) is adjusted by forcing the turbulent transport model with measured erosion rates. Second, three procedures are suggested to determine the erosion rate formula coefficients _f and : a global procedure and two different layer-by-layer procedures. Each procedure is applied to an erosion experiment conducted in a rotating annular flume by Villaret and Paulic (1986). The use of the layer-by-layer procedure based on a least squares fitting technique provides a closer fit than the global procedure. The present study points out the complementarity of experimental and numerical approaches and also suggests possible improvements in laboratory test procedures.     

Adsorption of fluoride on goethite surfaces-implications on dental epidemiology

Fluoride ion interaction with synthetically prepared goethite has been investigated over a range of pH values (4–9) and F^– concentrations (10^–3–10^–5 M). The amount of F^– retained by goethite suspensions was found to be a function of pH, media ionic strength, F^– concentration, and goethite concentration. The lowest ionic strength (0.001 M KNO₃) gave the highest adsorption medium. Uptake was minimal at pH >7 and increased with decreasing pH. Thermodynamic properties for fluoride adsorption at 298 K and 323 K were investigated. The isosteric heat of adsorption (H _r) was calculated and the heterogeneity and homogeneity of the surface examined for goethite. In view of the importance of fluoride in dental health, the interaction of fluoride on goethite in the physical environment has important implications on dental epidemiology.     

Fe-Cu-Zn-Mo同位素示踪氧化还原过程

非传统稳定同位素（Fe-Cu-Zn-Mo）理论与数据相结合提高了科研工作者对地质体系氧化还原过程的理解。本文对这一相对较新的领域进行了综述,包括与氧化还原过程相关的同位素分馏理论和实验约束、时空尺度下的氧逸度以及同位素示踪氧化还原过程。稳定同位素理论预测,Fe-Cu-Zn-Mo同位素应该对氧化还原状态的变化能够做出响应。结果表明,Fe同位素作为岩浆过程、表生过程、俯冲带流体性质"氧逸度计"应用前景广阔;Cu同位素在岩浆、热液、陆地系统可以很好地示踪氧化还原过程;Zn同位素由于络合过程分馏已经被用在许多不同环境中作为含硫/碳流体迁移的敏感示踪剂;Mo同位素作为古氧逸度计可有效重建古海洋-大气氧化还原状态。     

Characterizing heterogeneous permeable media with spatial statistics and tracer data using sequential simulated annealing

Characterizing heterogeneous permeable media using flow and transport data typically requires solution of an inverse problem. Such inverse problems are intensive computationally and may involve iterative procedures requiring many forward simulations of the flow and transport problem. Previous attempts have been limited mostly to flow data such as pressure transient (interference) tests using multiple observation wells. This paper discusses an approach to generating stochastic permeability fields conditioned to geologic data in the form of a vertical variogram derived from cores and logs as well as fluid flow and transport data, such as tracer concentration history, by sequential application of simulated annealing (SA). Thus, the method incorporates elements of geostatistics within the framework of inverse modeling. For tracer-transport calculations, we have used a semianalytic transit-time algorithm which is fast, accurate, and free of numerical dispersion. For steady velocity fields, we introduce a transit-time function which demonstrates the relative importance of data from different sources. The approach is illustrated by application to a set of spatial permeability measurements and tracer data from an experiment in the Antolini Sandstone, an eolian outcrop from northern Arizona. The results clearly reveal the importance of tracer data in reproducing the correlated features (channels) of the permeability field and the scale effects of heterogeneity.     

An examination of directional discontinuities and magnetic polarity changes around interplanetary sector boundaries usingE > 2 keV electrons

Past studies of interplanetary magnetic sector boundaries have been based on the assumption that one can determine the field polarities by comparing the field directions with those of the nominal Parker spiral angles. Previous investigators have found evidence for decreases of B, the magnitude of the magnetic fieldB, and increases of , the angle betweenB and the ecliptic plane, at sector boundaries. Others have argued that the characteristic thickness of sector boundaries exceeds that of tangential discontinuities, making sector boundaries a separate class of structures.We use a simple technique for inferring the polarities of interplanetary magnetic fields based on the assumption thatE > 2 keV electrons are always flowing along the magnetic field away from the Sun. Electron data from the UC Berkeley experiment on the ISEE-3 spacecraft are used to examine periods around several apparent sector boundaries in 1978 and 1979. We compare properties of (a) boundaries with field polarity changes and (b) large-angle ( > 60°) directional discontinuities with no field polarity changes. We find no significant differences between the sector boundaries and the directional discontinuities in terms of associated decreases in B or of values of . These results suggest no significant difference between sector boundaries and directional discontinuities other than the change in field polarities. Within limited statistics we find that about half the polarity changes would not have been identified using a requirement that > 90° and that half of the > 120° discontinuities would have been misidentified as polarity changes.     

Doppler velocity measurements made with a scanning photoelectric magnetograph

We discuss the problems connected with the measurements and evaluation of line-of-sight velocities, obtained with a scanning photoelectric magnetograph using a line-shifter with enhanced sensitivity. We bring arguments for the validity of the results of our photoelectric Doppler velocity recordings. We have found a network of cellularly shaped patterns in the distribution of photo-electrically measured line-of-sight motions, upflowing in the magnetically quiet (blue-shifted) and downflowing in magnetically active (red-shifted) areas of the photosphere, if the mean velocity level is estimated for a sufficiently large measured area. The features of both directions are mutually complementary. We demonstrate the effect of the shift of the reference zero velocity level on the topology of the line-of-sight velocity maps, and the dependence of this level on the size of the area from which it is estimated.