The generation kinetics of natural gases in the Kela-2 gas field from the Kuqa Depression, Tarim Basin, northwestern China

The Kela-2 gas field, found in the Kuqa Depression of the Tarim Basin, northwestern China, is a large-sized dry gas field (C1 /C1-5 =0.992 0.999) and characterized by ultra-high pressure (pressure factor up to 2.0 2.2). The pyrolysis experiment was carried out under isothermal gold-tube closed system, with samples collected from the Jurassic coal, Jurassic mudstone and Triassic mudstone in the Kuqa Depression. The result of gas yield showed that the Middle and Lower Jurassic source rocks have higher gas generation potential than the Triassic source rocks. The kinetic modeling of gas generation and methane carbon isotope fractionation suggested that the Kela-2 gases belong to the products of high-over mature stages and were mainly derived from the Middle and Lower Jurassic coal-bearing strata. The Triassic source rocks made a minor contribution to the Kela-2 gases. The Kela-2 gases chiefly generated from coal-bearing source rocks with R o values from 1.3% to 2.5%, and thus primarily accumulated after 5 Ma.     

略阳县柳树坪金矿成矿地质特征

略阳柳树坪金矿的含矿层为震旦系的碳酸盐岩沉积建造,金矿受震旦系层位(岩性)及构造双重因素制约.文中梳理了四个找矿标志.     

Spatial patterns and environmental factors influencing leaf carbon content in the forests and shrublands of China

Leaf carbon content (LCC) is widely used as an important parameter in estimating ecosystem carbon (C) storage, as well as for investigating the adaptation strategies of vegetation to their environment at a large scale. In this study, we used a dataset collected from forests (5119 plots) and shrublands (2564 plots) in China, 2011–2015. The plots were sampled following a consistent protocol, and we used the data to explore the spatial patterns of LCC at three scales: plot scale, eco-region scale (n = 24), and eco-region scale (n = 8). The average LCC of forests and shrublands combined was 45.3%, with the LCC of forests (45.5%) being slightly higher than that of shrublands (44.9%). Forest LCC ranged from 40.2% to 51.2% throughout the 24 eco-regions, while that of shrublands ranged from 35% to 50.1%. Forest LCC decreased with increasing latitude and longitude, whereas shrubland LCC decreased with increasing latitude, but increased with increasing longitude. The LCC increased, to some extent, with increasing temperature and precipitation. These results demonstrate the spatial patterns of LCC in the forests and shrublands at different scales based on field-measured data, providing a reference (or standard) for estimating carbon storage in vegetation at a regional scale.     

A Preliminary Study on a Seismotectonic Model for the Active Faults in the Xining Urban Area

On the basis of the Xining active urban fault survey, we studied the relationship between the active urban fault and fold deformation. The result of this research shows that the Huangshuihe fault and the NW-striking fault on the northern bank of the Huangshulbe River are tensional faults on top of an anticline, the Nanchuanhe fault is a transverse tear fault resulting from differential folding on two sides of the fault, the east bank of the Beichuanhe River fault is a compressional fault developed on the core or climb of a syncline. By balance profile analysis of fold deformation and inversion of gravity anomaly data, we obtained the depth of the detachment plane and established the seismotectonic model of the ）fining urban area. Based on the seismotectonic model, we analyzed the earthquake potential of the active urban fault.     

A Preliminary Study on the Datong Fault Belt

The Datong fault belt is a NE trending fault in the northern Qinghai-Xizang （Tibet） Plateau and controls the boundary of the Xining Basin and Datong Basin. It consists of the Maziying- Miaogou （F1） fault and the Laoye Mountain-Nanmenxia fault （F2）. There is obvious displacement in vertical direction along the belt. The field investigation results show that this belt has long-term activity. There are several meters long crushed zones and veins along the fault side in the basement rock. On the fault section, the Cambria system thrusts over the red- brick-colored Quaternary Period gravel, and there is a fault gouge of several centimeters thick developed on the fault plane. The fault gouge date （ESR） on the fault plane is 610 ± 61ka. The covering deluvial loess is not dislocated, and the OSL result is 14.6 ± 1.5ka. So it can be concluded that the fault belt was active in the middle Pleistocene, but inactive in the late Pleistocene according to the age data and geomorphologic features. Interior formations of the Datong basin features fold with the major axis orienting northwest. According to the relation of fault and fold deformation, Datong fault is a trausversal tear, which is due to uneven compression of the folds in different parts and NNE trending regional compressive stress. It is common among the NE trending faults in the northeast of Qinghai-Xizang （Tibet） Plateau. These NE trending faults aren＇t large, and most are located in the active plate. They are all nearly vertical to the axis of the folds and compressive basins.     

Decentralized robust control of building structures under seismic excitations

Many of the control algorithms proposed for structures subjected to seismic excitations are based on a centralized design philosophy, such as the linear quadratic regulator (LQR) design. The information of all the states of the system is usually required in these methods to determine the control command. For applications involving large‐scale systems, it may be more convenient to design decentralized controllers that depend only on the information of the local states for control command calculation. In this study, a nonlinear decentralized robust control algorithm is proposed. The structural system is decomposed into several artificially uncoupled subsystems. The interconnections between adjacent subsystems are treated as uncertain but bounded disturbances to the subsystems. The controller associated with one subsystem determines the control command based only on the states of the local subsystem. Numerical examples of linear and nonlinear structural models are presented to demonstrate the effectiveness and robustness of the proposed controller. The traditional LQR design is used as a baseline for comparison. Copyright © 2007 John Wiley & Sons, Ltd.     

Modified sublimation to isolate phenanthrene-degrading bacteria of the genera Sphingomonas and Burkholderia from Xiamen oil port

Sublimation was developed by Alley and Brown (2000) in order to isolate bacterial strains that were capable of degrading water insoluble compounds. In this study, sublimation was modified by the use of nutritional agar plates, instead of mineral salt agar, to isolate phenanthrene-degrading bacteria from a mixed culture that had been enriched under the selective pressure of high phenanthrene content. Five strains were obtained with different morphology and degradation ability. Based on the 16S rDNA sequence, two of them were classified as species of the genus Sphingomonas; the others as species of the genus Burkholderia. Denaturing gradient gel electrophoresis (DGGE) was introduced to detect dynamic changes in the bacterial community during enrichment batch culture, and to determine any correlation between the five isolates and the phenanthrene-degrading consortium. The DGGE profile indicated that these five isolates corresponded to four dominant bands of the consortium. Compared to traditional means of isolation, we concluded that modified sublimation is effective and more convenient.     

Asymmetric variability between maximum and minimum temperatures in Northeastern Tibetan Plateau: Evidence from tree rings

Ecological systems in the headwaters of the Yellow River, characterized by hash natural environmental conditions, are very vulnerable to climatic change. In the most recent decades, this area greatly attracted the public's attention for its more and more deteriorating environmental conditions. Based on tree-ring samples from the Xiqing Mountain and A'nyêmagên Mountains at the headwaters of the Yellow River in the Northeastern Tibetan Plateau, we reconstructed the minimum temperatures in the winter half year over the last 425 years and the maximum temperatures in the summer half year over the past 700 years in this region. The variation of minimum temperature in the winter half year during the time span of 1578―1940 was a relatively stable trend, which was followed by an abrupt warming trend since 1941. However, there is no significant warming trend for the maximum temperature in the summer half year over the 20th century. The asymmetric variation patterns between the minimum and maximum temperatures were observed in this study over the past 425 years. During the past 425 years, there are similar variation patterns between the minimum and maximum temperatures; however, the minimum temperatures vary about 25 years earlier compared to the maximum temperatures. If such a trend of variation patterns between the minimum and maximum temperatures over the past 425 years continues in the future 30 years, the maximum temperature in this region will increase significantly.     

Temporal variations of <Emphasis Type="Italic">δ</Emphasis><Superscript>18</Superscript>O of atmospheric water vapor at Delingha

Oxygen stable isotope of atmospheric water vapor is widely used to study the modern process of climate. Atmospheric water vapor samples were collected at Dlingha, northeast of Tibetan Plateau during the period from July 2005 to February 2006. The variation of δ ¹⁸O and the relationships between δ ¹⁸O and both the temperature and specific humidity are analyzed in this paper. Results show that the seasonal variation of δ ¹⁸O of atmospheric water vapor at Delingha is remarkable with higher δ ¹⁸O in summer and lower δ ¹⁸O in winter. The temporal variation of vapor δ ¹⁸O shows obvious fluctuations, with magnitude of over 37‰ The daily variation of the δ ¹⁸O is highly correlated with air temperature. The relationship between δ ¹⁸O and atmospheric water vapor content is complex. Study shows that δ ¹⁸O of atmospheric water vapor is positively correlated with specific humidity in winter in seasonal scale and inversely correlated with specific humidity in summer rainy period. The δ ¹⁸O values of atmospheric water vapor are lower than those of precipitation at Delingha, and the average difference is 10.7‰ Variations of δ ¹⁸O of atmospheric water vapor is also found to be affected by precipitation events, The model results show that the precipitation effect could have caused the vapor δ ¹⁸O in the raining season to lower by 7% in average in July and August. Supported by the National Natural Science Foundation of China (Grant Nos. 40671043, 40571039 and 40771048) and National Basic Research Program of China (Grant No. 2005CB422002)     

旅游者环境意识的调查与分析

根据环境意识结构设计了旅游者环境意识调查问卷,主要指标体系包括旅游环境知识水平、旅游环境态度、旅游环境评价和旅游环境行为4个方面.基于权重和赋分,构建了指标体系各部分评价模型和环境意识总体评价模型,以此来计算旅游者环境意识水平的综合得分.通过对内蒙古呼包鄂区域旅游者环境意识水平的调查分析得知,旅游者环境意识模式是"环境态度制约型"模式,从总体来看,环境知识不是制约旅游者环境意识水平的关键问题,环境评价也不是主导因素,而态度才是至为重要的因素,它决定了旅游者的环境行为倾向.