染料交换荧光分光光度法测定地球化学样品中痕量铊     

卢荫庥  安荣战 《岩矿测试》1993,12(4):251-254

研究表明，在Ｈ３ＰＯ４介质中，丁基罗丹明Ｂ可从乙酸异戊酯有机相中的［Ｔ１Ｂｒ４］＾－－结晶紫缔合物中置换结晶紫而形成新的离子缔合三元荧光络合物。详细考察了该络合物形成的最佳条件、荧光特征及萃取溶剂等，制定了地球化学样品中痕量Ｔ１的荧光光度测定新方法，其检出限０．００５μｇ／ｍｌ．Ｔ１量在０－０．５μｇ／ｍｌ范围与荧光强度呈正比。测定了含Ｔ１量０．６１－１．９μｇ／ｇ的８个一级地球化学标样，结果相符  相似文献   

743阳离子交换快速分离——ICPS-PGS2单道扫描直读光谱仪测定地质样品中15个微量稀土元素   总被引：1，自引：0，他引：1  

李荣辉  燕秀琴  郭冬发  赵胜利 《铀矿地质》1993,(3)

本文采用过氧化钠(Na_2O_2)熔样,743阳离子交换树脂快速分离,0.4mol/L柠檬酸25ml洗脱稀土,无需浓缩,即可用lCPS-PGS2单道扫描直读光谱仪直接测定15个微量稀土元素。在选择的最佳测量条件下,本法测定下限为0.005~g/ml(Eu)-0.50μg/ml(Ce),标准加入回收在88％—110％之间,样品分析精度为3.3％—17％,样品分析结果与参考值相符。本法适用于一般地质样品中微量稀土元素的例行分析。  相似文献   

743离子交换快速分离—等离子体光谱法同时测定十五个稀土元素   总被引：1，自引：0，他引：1  

吴锡凤  蒋铁珊 《铀矿地质》1993,(5)

本文研制了适用于地质样品中15个稀土元素分析的快速方法。样品经碱熔沉淀分离和743阳离子交换树脂分离富集将稀土元素制备成溶液用等离子体光谱法(ICP-AES)进行测量。方法检出限为0.002-0.3μg/g,当稀土元素含量为0.5-80,μg/g时,方法相对标准偏差为15％-2％。本方法经过多年的样品分析考验以及不断的改进和完善,证明方法简便快速,分析数据稳定可靠,能很好地满足地质样品中15个稀土分量测定的要求。  相似文献   

Direct Observations of Atmospheric Transport and Stratosphere-Troposphere Exchange from High-Precision Carbon Dioxide and Carbon Monoxide Profile Measurements     

You YI  Zhaonan CAI  Yi LIU  Shuangxi FANG  Yuli ZHANG  Dongxu YANG  Yong WANG  Miao LIANG  Maohua WANG 《大气科学进展》2020,37(6):608-616

The balloon-borne Aircore campaign was conducted in Inner Mongolia,China,on June 13 and 14 2018,which detected carbon dioxide(CO_2) and carbon monoxide(CO) profiles from surface to 24 km,showing strong positive and negative correlations between 8 km and 10 km on 13 and 14 June,respectively.Backward trajectories,meteorological analyses,and CO_2 horizontal distributions were combined to interpret this phenomenon.The results indicated that the source region experienced a stratospheric intrusion and exhibited a large horizontal CO_2 gradient;namely,lower CO concentrations corresponded to higher CO_2 concentrations and vice versa.The laminar structure with multiple origins resulted in the highly negative correlation between CO_2 and CO in the upper troposphere on 14 June.The contribution of stratospheric air mass to the upper troposphere and that of tropospheric air mass to the lower stratosphere were 26.7% and24.3%,respectively,based on a mass balance approach.Another interesting phenomenon is that CO_2 and CO concentrations increased substantially at approximately 8 km on 13 June.An analysis based on the backward trajectory implied that the air mass possibly came from anthropogenic sources.The slope of CO_2/CO representing the anthropogenic sources was 87.3 ppm ppm~(-1).In addition,the CO_2 profile showed that there was a large CO_2 gradient of 4 ppm km-1 within the boundary layer on 13 June,and this gradient disappeared on 14 June.  相似文献   

论大陆岩石圈形成过程中的克拉通化阶段     

惠鹤九  陈斌  郑永飞  赵子福 《地学前缘》2002,9(4):0-0

流体控制着地球系统中质量和能量的传输。流体岩石反应过程在岩石圈中是十分普遍的现象。在流体流动体系中 ,流体在岩石裂隙中通过平流、扩散、水动力弥散和动力学弥散等方式进行输运并与岩石发生同位素交换反应。文章首先对封闭体系、“封闭”体系、开放体系以及缓冲体系中的同位素交换模型进行了简单讨论 ,然后在讨论氧同位素动力学交换机制的基础上 ,建立了平衡交换模型和动力学交换模型。结合流体流动的归一化速率、弥散系数和流体岩石的反应速率等变量 ,对流体岩石交换反应的流体运动方程中的Peclet数和Damk¨ohler数进行了讨论 ,并详细解释了它们在流体岩石交换反应过程中的物理意义和地质用途。  相似文献   

Seasonal variations and mechanism for environmental control of NEE of CO_2 concerning the Potentilla fruticosa in alpine shrub meadow of Qinghai-Tibet Plateau     

《中国科学D辑(英文版)》2006,(Z2)

The study by the eddy covariance technique in the alpine shrub meadow of the Qing-hai-Tibet Plateau in 2003 and 2004 showed that the net ecosystem carbon dioxide exchange (NEE) exhibited noticeable diurnal and annual variations, with more distinct daily changes during the warmer seasons. The CO2 emission of the shrub ecosystem culminated in April and September while the CO2 absorption capacity reached a maximum in July and August. The absorbed carbon dioxide during the two consecutive years was 231.4 and 274.8 g CO2·m-2 respectively, yielding an average of 253.1 gCO2·m-2 per year: that accounts for a large proportion of absorbed CO2 in the region. Obviously, the diurnal carbon flux was negatively related to temperature, radiation and other atmospheric factors. Still, minute discrepancies in kurtosis and duration of carbon emission/absorption were detected between 2003 and 2004. It was found that the CO2 flux in the daytime was similarly affected by photosynthetic photon flux density in both years. Temperature appears to be the most important determinant of CO2 flux: specifically, the high temperature during the plant growing season inhibits the carbon absorption capacity. One potential explanation is that soil respiration is enhanced under such condition. Analysis of biomass revealed that the annual net carbon fixed capacity of aboveground and belowground biomass was 544.0 in 2003 and 559.4 g Cm"2 in 2004, which coincided with the NEE absorption capacity (63.1 g C·m-2 in 2003 and 74.9 g C·m-2 in 2004) in the corresponding plant growing season.  相似文献   

Effect of water stress on ecosystem photosynthesis and respiration of a Leymus chinensis steppe in Inner Mongolia     

《中国科学D辑(英文版)》2006,(Z2)

Many studies on global climate have forecast major changes in the amounts and spatial patterns of precipitation that may significantly affect temperate grasslands in arid and semi-arid regions. As a part of ChinaFLUX, eddy covariance flux measurements were made at a semi-arid Leymus chinensis steppe in Inner Mongolia, China during 2003-2004 to quantify the response of carbon exchange to environmental changes. Results showed that gross ecosystem production (FGEP) and ecosystem respiration (Reco) of the steppe were significantly depressed by water stress due to lack of precipitation during the growing season. Temperature was the dominant factor affecting FGEP and Reco in 2003, whereas soil moisture imposed a significant influence on both Reco and FGEP in 2004. Under wet conditions, Reco showed an exponentially increasing trend with temperature (Q10 = 2.0), but an apparent reduction in the value of Reco and its temperature sensitivity were observed during the periods of water stress (Q10=1.6). Both heat and water stress can cause decrease in FGEP. The sea-sonality of ecosystem carbon exchange was strongly correlated with the variation of precipitation. With less precipitation in 2003, the steppe sequestrated carbon in June and July, and went into a senescence in early August due to water stress. As compared to 2003, the severe drought during the spring of 2004 delayed the growth of the steppe until late June, and the steppe became a CO2 sink from early July until mid-September, with ample precipitation in August. The semi-arid steppe released a total of 9.7 g C·m-2 from May 16 to the end of September 2003, whereas the net carbon budget during the same period in 2004 was close to zero. Long-term measurements over various grasslands are needed to quantify carbon balance in temperate grasslands.  相似文献   

郑家-王庄地区沙一段粘土矿物特征及对储层敏感性影响   总被引：5，自引：0，他引：5  

张关龙  陈世悦  鄢继华 《矿物学报》2006,26(1):99-106

东营凹陷郑家—王庄地区沙一段砂岩储集层中蕴藏大量稠油油藏,但开发过程中粘土矿物的敏感性严重制约了该油类藏的有效开发。定向X射线衍射分析结果表明,本区沙一段砂岩储层中粘土矿物组成类型为伊/蒙无序间层矿物(S/I)、高岭石、伊利石和绿泥石,其中以伊/蒙无序间层矿物的相对含量居多。这就决定了研究区储层敏感性以水敏性为主,其余敏感性无或较弱。据定向X射线衍射谱图上S/I主峰d值大小,进一步识别出钙型S/I、钠型S/I及钙钠过渡型S/I。扫描电镜观察表明,S/I具有丝状、网状和蜂窝状三种形态,且大都包裹在岩石骨架颗粒的表面作为孔隙衬里而存在。阳离子交换容量和膨胀率研究结果显示,二者与样品中S/I含量和层间阳离子类型相关。膨胀率和阳离子交换量与S/I含量都呈较好的正相关关系。在S/I中蒙皂石层含量相当的情况下,钠型S/I的膨胀率和阳离子交换量值偏大,钙型偏小,钙钠过渡型居中。此外,粘土总量以及S/I产状对储层损害也有较大的影响。  相似文献   

The effect of mountainous topography on moisture exchange between the “surface” and the free atmosphere   总被引：1，自引：0，他引：1  

Andreas P. Weigel  Fotini K. Chow  Mathias W. Rotach 《Boundary-Layer Meteorology》2007,125(2):227-244

Typical numerical weather and climate prediction models apply parameterizations to describe the subgrid-scale exchange of moisture, heat and momentum between the surface and the free atmosphere. To a large degree, the underlying assumptions are based on empirical knowledge obtained from measurements in the atmospheric boundary layer over flat and homogeneous topography. It is, however, still unclear what happens if the topography is complex and steep. Not only is the applicability of classical turbulence schemes questionable in principle over such terrain, but mountains additionally induce vertical fluxes on the meso-γ scale. Examples are thermally or mechanically driven valley winds, which are neither resolved nor parameterized by climate models but nevertheless contribute to vertical exchange. Attempts to quantify these processes and to evaluate their impact on climate simulations have so far been scarce. Here, results from a case study in the Riviera Valley in southern Switzerland are presented. In previous work, measurements from the MAP-Riviera field campaign have been used to evaluate and configure a high-resolution large-eddy simulation code (ARPS). This model is here applied with a horizontal grid spacing of 350 m to detect and quantify the relevant exchange processes between the valley atmosphere (i.e. the ground “surface” in a coarse model) and the free atmosphere aloft. As an example, vertical export of moisture is evaluated for three fair-weather summer days. The simulations show that moisture exchange with the free atmosphere is indeed no longer governed by turbulent motions alone. Other mechanisms become important, such as mass export due to topographic narrowing or the interaction of thermally driven cross-valley circulations. Under certain atmospheric conditions, these topographical-related mechanisms exceed the “classical” turbulent contributions a coarse model would see by several times. The study shows that conventional subgrid-scale parameterizations can indeed be far off from reality if applied over complex topography, and that large-eddy simulations could provide a helpful tool for their improvement.  相似文献   

The thermodynamic structure atop a penetrating convective thunderstorm     

Pao K. Wang   《Atmospheric Research》2007,83(2-4):254-262

The thermodynamic structure on top of a numerically simulated severe storm is examined to explain the satellite observed plume formation above thunderstorm anvils. The same mechanism also explains the formation of jumping cirrus observed by Fujita on board of a research aircraft. A three-dimensional, non-hydrostatic cloud model is used to perform numerical simulation of a supercell that occurred in Montana in 1981. Analysis of the model results shows that both the plume and the jumping cirrus phenomena are produced by the high instability and breaking of the gravity waves excited by the strong convection inside the storm. These mechanisms dramatically enhance the turbulent diffusion process and cause some moisture to detach from the storm cloud and jump into the stratosphere. The thermodynamic structure in terms of the potential temperature isotherms above the simulated thunderstorm is examined to reveal the instability and wave breaking structure. The plumes and jumping cirrus phenomena represent an irreversible transport mechanism of materials from the troposphere to the stratosphere that may have global climatic implications.  相似文献