冲淤变动型沟谷泥石流防治结构及计算   总被引：10，自引：0，他引：10  

王蓉  翁其能  陈洪凯 《山地学报》2001,(Z1)

本文以平川沟泥石流为例 ,基于对冲淤变动型沟谷泥石流基本特性的分析 ,遵循“以泄为主、导排结合”的防治原则 ,提出了有效治理此类泥石流的汇流 #速流结构 ;运用地基梁计算理论对速流槽进行了力学分析计算 ,比较详细地进行了汇流槽侧墙、锚固桩的内力计算。  相似文献   

柴达木盆地东台吉乃尔盐湖盐类沉积特征及成盐年代的初步研究   总被引：3，自引：0，他引：3  

张辉  韩凤清  梁青生 《化工矿产地质》2001,23(2):83-85

东台吉乃尔盐湖经过长期的成盐演化和成矿过程 ,最终形成了以氯化钠化学沉积为主的蒸发盐 ,晶间卤水富含B、Li等多种元素卤水矿床 ,根据 1998年对该湖干盐滩中部所打的CK1孔钻孔剖面( 12m)及测试的几个14 C年龄 ,初步证实该盐湖上部盐层是在约 10 0 0 0aBP形成 ,未经碳酸盐和硫酸盐成盐阶段 ,盐湖形成初期即进入氯化物成盐阶段。  相似文献   

中国峨眉山地区湿沉降化学   总被引：6，自引：0，他引：6  

柳泽文孝  贾疏源  益田晴惠  杨慧东  万新南  中屋真司  北田奈绪子 《矿物岩石》2001,21(4):97-99

近年，酸雨是世界上最严重的环境问题之一。峨眉山位于四川盆地的西南缘。峨眉山酸雨频率达到85．4％，雨水pH值平均为4．37。冷杉分布于海拔1700m-3098m区域，森林遭到破坏。为了弄清峨眉山污染物质的来源，从1998年4月开始在22个取样点每月采集水样。本文中主要论述1998年6月的雨水化学成分特征。  相似文献   

我国再次发现硒铅矿     

彭新建  罗兴章  张文兰  闵茂中  南京大学 《矿物学报》2001,21(2):133-136

本文报道了我国再次在华南6217花岗岩型铀矿床中发现硒铅矿，测定了该矿物的化学成分，结合该铀矿床的矿物组合和成矿物理化学条件，讨论了硒铅矿的生成环境。  相似文献   

The aeolian dust accumulation curve     

Dirk Goossens 《地球表面变化过程与地形》2001,26(11):1213-1219

This article presents a simple physical concept of aeolian dust accumulation, based on the behaviour of the subprocesses of dust deposition and dust erosion. The concept is tested in an aeolian dust wind tunnel. The agreement between the accumulation curve predicted by the model and the accumulation curve obtained in the experiments is close to perfect and shows that it is necessary to discriminate between the processes of aeolian dust deposition and aeolian dust accumulation. Two important thresholds determine the accumulation process. For wind speeds below the deflation threshold, the aeolian accumulation of dust increases linearly with the wind speed. For wind velocities between the deflation threshold and the accumulation limit, the sedimentation balance is above unity and there is still accumulation, though it rapidly drops once the deflation threshold has been exceeded. At wind speeds beyond the accumulation limit, the sedimentation balance is below unity and there will no longer be an accumulation of dust. The thresholds have been determined in a wind tunnel test at friction velocity u_* = 0·34 m s^?1 (deflation threshold) and u_* = 0·43 m s^?1 (accumulation limit), but these values are only indicative since they depend heavily on the characteristics of the accumulation surface and of the airborne grains. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

区域酸性沉降的数值研究 I. 模式   总被引：17，自引：3，他引：17  

王体健  李宗恺  南方 《大气科学》1996,20(5):606-614

建立了一个三维时变的欧拉型区域酸性污染物沉降模式，模式包括源排放、平流输送、湍流扩散、干沉积、气相化学、液相化学及湿清除等六大部分。考虑到计算条件的承受能力和应用性的要求，在把握酸沉降形成的关键过程的前提下，合理地简化设计模式。相对于国内已有的工作，本模式在干沉积、气相化学、液相化学和湿清除等方面均有所改进。  相似文献   

800KaB．P．来西藏“一江两河”中游地区的气候与西南季风变化     

靳鹤龄  董光荣  李森  刘玉璋  申建友  曹继秀 《中国沙漠》1996,(1)

西藏“一江两河”中游地区风成地层沉积时代、沉积相和磁化率等研究结果表明，早在８００ＫａＢ．Ｐ．前西南季风就已存在，受全球气候波动和青藏高原隆起的影响，其盛行衰变与东南季风具有较好的一致性，主要表现为本区地层所记录的气候变化信息不如东南季风区详细；而且西南季风因高原屏障作用给本区带来的降水愈来愈少，气候明显地向干冷化发展。  相似文献   

A novel ozone sensor for direct eddy flux measurements     

Hans Güsten  Günther Heinrich  Ralf W. H. Schmidt  Ulrich Schurath 《Journal of Atmospheric Chemistry》1992,14(1-4):73-84

A small, lightweight (1.5 kg) and fast-response ozone sensor for direct eddy flux measurements has been built. The basis for detection is the chemiluminescence of an organic dye adsorbed on dry silica gel in the reaction with ozone. The chemiluminescence is monitored with a cheap and small blue-sensitive photomultiplier. At a flow rate of 100 l min^-1 the ozone sensor has a 90% response time of significantly better than 0.1 s with a detection limit lower than 50 ppt at S/N=3. There are no interferences from other atmospheric trace gases like NO_x, H₂O₂ and PAN. Water vapour and SO₂ enhance the chemiluminescence efficiency of the ozone sensor. Since their response times are 22 seconds and 30 minutes, respectively, no correlation between rapid ozone fluctuations and those of these two trace gases is noticed by the ozone sensor when operating at a frequency of 10 Hz.The ozone sensor was tested for several weeks in continuous measurements of ozone fluxes and deposition velocities over different croplands using the eddy correlation technique. Good agreement was found between ozone dry deposition velocities derived from profile measurements and by eddy correlation.  相似文献   

A Eulerian air pollution model for Europe with nonlinear chemistry   总被引：1，自引：0，他引：1  

Z. Zlatev  J. Christensen  Ø. Hov 《Journal of Atmospheric Chemistry》1992,15(1):1-37

A long-range transport model with nonlinear chemical reactions is described. The model contains 35 pollutants and 70 chemical reactions. This is a Eulerian model defined on a space domain containing the whole of Europe. The spherical space domain (corresponding to the Earth's surface covered by the model) is mapped into a square plane domain and discretized by using a 32×32 grid. The grid increments are equidistant (both along the Ox axis and along the Oy axis). The choice of values of the physical parameters involved in the model and the numerical treatment of the model are shortly discussed. The model is tested with meteorological data for 1985 and 1989. The numerical results are compared with measurements at stations located in different European countries. Extensive comparisons of ozone concentrations for July 1985 with measurements taken at 24 European stations are also carried out. Results concerning three episodes in July 1985 as well as results obtained in the study of the sensitivity of the ozone concentrations to variations of NO _x and/or anthropogenic VOC emissions are presented. The advantages and the limitations of such a model are discussed. The model is continuously improved by adding new modules to it. The plans for improvements in the near future are outlined.  相似文献   

Covariations in oceanic dimethyl sulfide,its oxidation products and rain acidity at Amsterdam Island in the Southern Indian Ocean   总被引：5，自引：0，他引：5  

B. C. Nguyen  N. Mihalopoulos  J. P. Putaud  A. Gaudry  L. Gallet  W. C. Keene  J. N. Galloway 《Journal of Atmospheric Chemistry》1992,15(1):39-53

Simultaneous measurements of rain acidity and dimethyl sulfide (DMS) at the ocean surface and in the atmosphere were performed at Amsterdam Island over a 4 year period. During the last 2 years, measurements of sulfur dioxide (SO₂) in the atmosphere and of methane sulfonic acid (MSA) and non-sea-salt-sulfate (nss-SO₄ ^2-) in rainwater were also performed. Covariations are observed between the oceanic and atmospheric DMS concentrations, atmospheric SO₂ concentrations, wet deposition of MSA, nss-SO₄ ^2-, and rain acidity. A comparable summer to winter ratio of DMS and SO₂ in the atmosphere and MSA in precipitation were also observed. From the chemical composition of precipitation we estimate that DMS oxidation products contribute approximately 40% of the rain acidity. If we consider the acidity in excess, then DMS oxidation products contribute about 55%.  相似文献