NUMERICAL STUDY ON DOMINATING FACTOR AND KEY AREA OF EL NINO CYCLE FORMATION*

A coupled model,which is employed to study the dominating factor and key area of El Nino cycle formation,consists of a dynamical ocean model and a statistical atmospheric model.The coupled model with seasonal forcing successfully reproduces the El Nino event cycle which exhibits quasi-regular oscillations with a preferred period of about 4 years.The results show that the heat content(HC) is transported between the eastern and the western tropical Pacific areas.The spatial distribution of HC anomalies for four phases of the whole cycle clearly shows a possible formation mechanism of El Nino.Experiments further suggest that sea surface temperature in the tropical Pacific and HC in the central tropical Pacific are the most important factors and the central tropical Pacific is the most important area for determining formation of El Nino cycle.     

Tectono-Sedimentary History of Southeastern Coast Region,China:a Synthesis

According to the ideas and concepts of systems dynamic of continent structure, using previous information related to the study area, combining analyses on orogenic belt, basin and magmatic rock, the present paper synthesizes the tectono-sedimentary development of southeastern coast region, China, with special emphasis on the mountain making, basining and magmafc activity. The tectonic evolution after Late Caledonian orogeny was dominated by alternating rifting and converging, subsiding and uplifting, mountain making and basining in central and southern parts of southeastern China and the adjacent regions to the east and west. Seventeen geologic events, nine events of plate or terrain convergence , and continental crust accretion, as well as eight events of intracontinental rifting and basin faulting , are closely related to the tectonic and sedimentary evolution of the study area. The accompanied intense and frequent sedimentation , folding , faulting , magmatism and ore-forming process allowed huge coal     

大瑶山隧道现场测试及稳定性分析

大瑶山隧道是正在修建的我国目前最长的双线铁路隧道,是京广复线上的关键工程,全长14.3km,最大埋深900m。本文介绍了在滑石排一号和二号斜井附近所进行的现场试验和观测结果,包括岩体初始应力,隧洞开挖后二次应力,收敛观测,以及利用预埋多点伸长计和挠度计所作的隧道侧壁和顶板位移观测。根据观测资料及有限元分析计算对隧道的稳定性进行了一般性评价。     

基于正交多项式逼近法的岩土参数概率分布推断

针对岩上参数样本容量较大的情况,基于数值分析中的逼近原理,直接根据试验样本值,运用勒让德正交多项式来拟合岩土参数的概率密度函数,并用K-S检验法从理论上证明所求的密度函数的正确性和实用性。     

Analysis on Bearing Capacity of Tunnel-Type Anchorage of a Long-Span Suspension Bridge

INTRODUCTION Tunnel typeanchoragehasobviousadvantages inbearingcapacityversusinvestment(LiuandHu,1996).However,itisrarelyusedinapracticalpro jectbecauseofitsrequirementofgoodrockcondi tions.Siduhebridge(Fig.1),whichliesintheBa dongmountainsinthewestplatea…     

Estimates of potential nitrate reductase activity in sediments: comparisons of two incubation methods and four inhibitors

Sediment samples, collected from a large shallow lake, Taihu, China, were incubated in two conditions (with and without air extraction) with regard to four soil enzyme’s inhibitors (dry and moist heat sterilizations, chloramphenicol and toluene) to estimate the potential nitrate reductase (Nar) activities. The objectives of paper were to define (1) whether to exclude air from the mixture of sediment and substrate solution prior to incubation was necessary, and (2) the efficacy of four inhibitors when assaying the enzyme. No significant difference between two incubation methods was found (P < 0.05), indicating that it is not necessary for estimating the potential Nar activity in the sediment to construct an initial anaerobic condition by air extractions prior to incubation. Toluene (1.0 mL/g sediment) and dry heat sterilization effectively and persistently inhibit the reduction of nitrate to nitrite during the incubation of 42 h. The authors concluded that both should be used as preferred inhibitors. In contrast, chloramphenicol (30 μg/g sediment) and moist heat sterilization inhibitors restrained nitrate reduction for <24 h only. In addition, it was found that no nitrite produced was substantially reduced in 24 h. Therefore, it should be needless for potential Nar activity estimation in the sediment to add 2,4-dinitrophenol to inhibit nitrite reductase.     

The effect of desertification on carbon and nitrogen status in the northeastern margin of the Qinghai-Tibetan Plateau

Environmental degradation resulting from desertification often accelerates biodiversity loss and alters carbon (C) and nitrogen (N) stocks within grassland ecosystem. In order to evaluate the effect of desertification on plant diversity and carbon (C) and nitrogen (N) stocks, species compositions and C and N contents in plants and soil were investigated along five regions with different degrees of desertification in the northeastern margin of the Qinghai-Tibetan Plateau (control, light, moderate, severe and very severe stages). The study showed: (1) species composition and richness changed significantly with the development of grassland desertification; (2) the aboveground biomass C and N contents in the control were 101.60 and 4.03 g m^?2, respectively. Compared to the control, the aboveground tissue C and N contents significantly decreased from light, moderate, severe to very severe stages. (3) The root C and N contents in the control in 0–40 cm depth are 1,372.83 and 31.49 g m^?2, respectively, while the root C and N contents in 0–40 cm were also declining from the control, light, moderate, severe to very severe stages. (4) Compared to the plant, the soil made a greater contribution for C and N distribution, in which the soil organic C and total N contents in 0–40 cm depth in the control are 20,386.70 and 3,587.89 g m^?2, respectively. At the same time, soil organic C and N contents also decreased significantly from the control to very severe stages. These results suggest that grassland desertification not only alters species compositions and leads to the loss of plant diversity, but also results in greater loss of organic C and N in alpine meadow, in which there is a negative effect on reducing greenhouse gas emission.     

富氟花岗岩中萤石岩浆成因的新证据

通过富氟花岗岩-HF-H2O体系的熔化-结晶实验,在620～700℃、1×108Pa条件下获得了石英+碱性长石+黄玉+云母+萤石的矿物组合.在该实验体系中首次发现了八面体萤石.实验结果表明,在岩浆条件下可以形成萤石,从而为富氟花岗岩中萤石的岩浆成因提供了新证据.     

建造地下空间的新途径--同步爆扩成型地下空间和混凝土支护层

对于地下空间资源的开发利用,提出了同步爆扩成型地下空间和混凝土支护层的新方法。这一方法也可用于深基坑开挖与支护、地基处理、大面积开挖和地下水防治等岩土工程。     

大兴安岭中南段金属矿床流体包裹体研究

作者通过在不同温度下对包裹体特征、相变行为的系统观察与测定，以及对包裹体气、液相成分的分析、获取了研究区内主要矿床成矿过程中成矿液体的温度、盐度、密度、流体成分、流体的沸腾现象、成矿压力以及ＰＨ，Ｅｈ，Ｆｏ２，还原参数等成矿的物理化学参数，从而为划分矿化蚀变阶段，矿床类型、成矿系列和深化对矿床成矿作用与成矿机制的认识提供了科学依据。尽管矿床属于不同的成矿系列，只要矿床类型相同，矿床的流体包裹体地球