Carius管直接蒸馏快速分离锇方法的改进

蒸馏法是Re-Os同位素测量体系从基质中分离Os的一种快捷方法,但装置繁琐,清洗工作量大,已成为限制其应用的瓶颈。文章对Carius管传统蒸馏装置进行了改进,利用橡胶滴头代替硅胶管和玻璃堵头自制Carius管直接蒸馏接口装置,简化了气体进出口管路,使用电蒸笼代替电热套,对蒸馏时间、样品溶液稀释倍数和吸收液体积等蒸馏条件进行了优化。改进后的装置升温速度、稳定性和简便性得到提高,简化了实验器皿,有利于降低空白,实现在较小操作空间内大批量样品的同时处理。Carius管直接蒸馏实验结果表明,Os的回收率可达86.7%～95.2%。在长时间(2 h)蒸馏条件下,Os回收率比传统蒸馏瓶法高约41%。针对不同样品类型和测试仪器,可选择相应的蒸馏条件,有效压缩了样品处理时间,提高了测量计数。对Re-Os定年标准物质GBW 04436(JDC)测定5次的模式年龄为(139.5±1.9)Ma～(142.0±2.1)Ma,标准物质GBW 04435(HLP)测定2次的模式年龄为(220±3.3)Ma～(223.0±3.2)Ma,分别与标准值(139.6±3.8)Ma和(221.4±5.6)Ma在不确定度范围内一致。改进后的Carius管直接蒸馏装置已应用于日常样品处理。     

电感耦合等离子体发射光谱法同时测定长石矿物中钾钠钙镁铝钛铁

样品用HCl-HNO3-HClO4-HF分解,电感耦合等离子体发射光谱法同时测定长石矿物中的K、Na、Ca、Mg、Al、Ti、Fe。对元素的分析谱线、溶解用酸的量等工作条件进行了优化,选择了各元素的最佳分析谱线及背景校正模式,探讨HF的用量,试验加内标和不加内标两种测定方法对测定结果的影响。结果表明,对于样品中含量较高的Al,选用次灵敏线396.152 nm,用内标法补偿非光谱干扰,以长石中含量极低的Au作为内标元素(测定谱线为242.795 nm)可以获得满意的结果,方法检出限为0.45～3.56μg/g。经国家一级标准物质GBW03134、GBW 3116验证,测定值的相对误差(RE)为-1.32%～10.0%,ICP-AES法与其他测定方法的测定结果无显著性差异,方法精密度(RSD,n=10)为0.55%～7.2%,能够满足长石矿物中相关组分的准确测定。     

电感耦合等离子体质谱法对白钨矿中稀土元素的准确测定——以云南麻栗坡南秧田白钨矿床的成因探讨为例

通过建立的高分辨电感耦合等离子体质谱测定稀土元素( REEs)的分析方法,准确测定出麻栗坡南秧田白钨矿床两类不同矿体的围岩和矿石中稀土元素的含量,方法的灵敏度高,检出限低,精密度和准确度均非常满意.通过对稀土元素地球化学特征的研究,表明存在两种不同成因的白钨矿,一为与围岩同时沉积形成的白钨矿,在变质作用条件下形成了矽卡岩型白钨矿;二为后期热液携带来的具有较高稀土含量的石英脉型白钨矿.前者具有轻稀土元素富集、重稀土亏损、中等程度的Eu、Ce负异常等特征,与沉积环境关系密切,推测是海底火山喷发(喷流)沉积变质作用的产物;后者具有较低的稀土总量∑REEs以及显著的Eu正异常特征,表现出较高的稀土分馏特性,为后期热液作用形成,并对先期矿体有叠加改造作用,使矿化更加富集.     

电感耦合等离子体发射光谱法测定油田水中的硼

样品经硝酸酸化、滤膜过滤处理后,用电感耦合等离子体发射光谱法直接测定其中硼的含量。通过正交实验优选仪器参数和分析谱线,在选定的波长208.959 nm下,对样品稀释倍数和介质酸种类进行选择,结果表明,硼含量低于10 mg/L的样品不用稀释,高于10 mg/L的样品一般稀释20倍,介质选用硝酸可使测定结果更加准确。对油田水中共存的7种主要金属元素进行了干扰试验,样品中存在20 mg/L的Sr、Ba、Fe,50mg/L的Mg、Ca,100 mg/L的K,200 mg/L的Na对待测元素的测定没有影响。选取油田水样品进行加标回收试验,方法平均回收率为95.3%～102.0%,精密度(RSD,n=11)为0.43%～0.92%,检出限为0.0020mg/L。方法简便、快速,结果令人满意,与姜黄素分光光度法比较,克服了分析流程长、使用试剂较多且不易操作的不足。     

地质力学矿田构造的进展与前景

[摘 要]地质力学矿田构造研究秉承李四光教授构造体系的理论和方法,研究地质构造对成矿区带、矿田、矿床及与成矿有关的岩层、岩体、脉体的形成、改造、分布的控制规律和内在作用机理,实现矿产资源找寻和勘查突破,这是矿田构造研究的基本任务。本文归纳总结了地质力学矿田构造在内生矿产资源方面所取得的成就和进展,指出了地质力学矿田构造预期的发展前景和发展方向,该门学科将在指导矿产资源调查评价和勘探开发中,为国家矿产资源的寻找和勘查作出重要贡献。     

Coupled and splitting bedload sediment transport models based on a modified flux-wave approach

Numerical modeling of free-surface flow over a mobile bed with predominantly bedload sediment transport can be done by solving the shallow water and Exner equations using coupled and splitting approaches.The coupled method uses a coupling of the governing equations at the same time step leading to a non-conservative solution.The splitting method solves the Exner and the shallow water equations in a separate manner,and is only capable of modeling weak free-surface and bedload interactions.In the current study,an extended version of a Godunov-type wave propagation algorithm is presented for modeling of morphodynamic systems using both coupled and splitting approaches.In the introduced coupled method the entire morphodynamic system is solved in the form of a conservation law.For the splitting technique,a new wave Riemann decomposition is defined which enables the scheme to be utilized for mild and strong interactions.To consider the bedload sediment discharge within the Exner equation,the Smart and Meyer-Peter&Müller formulae are used.It was found that the coupled solution gives accurate predictions for all investigated flow regimes including propagation over a dry-state using a Courant-Friedrichs-Lewy(CFL)number equal to 0.6.Furthermore,the splitting method was able to model all flow regimes with a lower CFL number of 0.3.     

RETRIEVING ATMOSPHERIC TEMPERATURE FROM NOAA-15 ATOVS MEASUREMENTS*

This paper describes briefly the sounding capabilities of TOVS/ATOVS onboard the NOAA polar-orbiting meteorological satellites,followed by a more detailed review of the retrieval schemes.The ICI physical retrieval scheme with some adaptations is implemented in our experiment.The analyses of the Chinese regional NWP model are utilized to create a rolling library of initial guess field.Retrieval results validated against both NWP analyses and radiosondes indicate good agreement between ICI retrievals and conventional observations.Preliminary result from the PC-ATOVS Windows display system of NSMC will also be shown.     

Optimal design of a groundwater monitoring network in Daqing,China

In the Daqing region of China there are 34 groundwater well fields with a groundwater withdrawal of 81.9×10⁴ m³/d. Due to over-abstraction of the groundwater resources from the 1960s to present, a cone of depression up to 4,000 km² has formed in the area. To monitor the change in the groundwater environment, it is necessary to design an effective groundwater-monitoring network. The sites for monitoring groundwater level were selected by applying the finite-element method coupled with Kalman filtering to the area in which the groundwater resources have been extensively exploited. The criterion is a threshold value of the standard deviation of estimation error. This threshold value is determined by the tradeoff between maximum information and minimum cost, in which the maximum information is characterized by the standard deviation and the minimum cost is equivalent to the number of observation wells. The groundwater flow model was calibrated by an optimal algorithm coupled the finite-element method with Kalman filtering by using the data from 16 observation wells from 1986 to 1993. A simulation algorithm coupled with the finite-element method with Kalman filtering analyzed the location data obtained from the existing 38 observation wells in the same region. The spatial distribution of standard deviation of estimation error is computed and the locations that have the maximum standard deviation are selected as additional sites for augmenting the existing observational well network at a given threshold value of the standard deviation surface. Based on the proposed method for selecting a groundwater level monitoring network, an optimal monitoring network with 88 observation wells with the measurement frequency of 12 times per year is selected in the Daqing region of China.     

Discrete Element Modeling of Stress and Strain Evolution Within and Outside a Depleting Reservoir

Stress changes within and around a depleting petroleum reservoir can lead to reservoir compaction and surface subsidence, affect drilling and productivity of oil wells, and influence seismic waves used for monitoring of reservoir performance. Currently modeling efforts are split into more or less coupled geomechanical (normally linearly elastic), fluid flow, and geophysical simulations. There is evidence (from e.g. induced seismicity) that faults may be triggered or generated as a result of reservoir depletion. The numerical technique that most adequately incorporates fracture formation is the DEM (Discrete Element Method). This paper demonstrates the feasibility of the DEM (here PFC; Particle Flow Code) to handle this problem. Using an element size of 20 m, 2-D and 3-D simulations have been performed of stress and strain evolution within and around a depleting reservoir. Within limits of elasticity, the simulations largely reproduce analytical predictions; the accuracy is however limited by the element size. When the elastic limit is exceeded, faulting is predicted, particularly near the edge of the reservoir. Simulations have also been performed to study the activation of a pre-existing fault near a depleting reservoir.     

Prediction of free field vibrations due to pile driving using a dynamic soil–structure interaction formulation

This paper presents a numerical model for the prediction of free field vibrations due to vibratory and impact pile driving. As the focus is on the response in the far field where deformations are relatively small, a linear elastic constitutive behaviour is assumed for the soil. The free field vibrations are calculated by means of a coupled FE–BE model based on a subdomain formulation. First, the case of vibratory pile driving is considered, where the contributions of different types of waves are investigated for several penetration depths. In the near field, the soil response is dominated by a vertically polarized shear wave, whereas in the far field, body waves are importantly attenuated and Rayleigh waves dominate the ground vibration. Second, the case of impact pile driving is considered. A linear wave equation model is used to estimate the impact force during the driving process. Apart from the response of a homogeneous halfspace, it is also investigated how the soil stratification influences the ground vibration for the case of a soft layer on a stiffer halfspace. When the penetration depth is smaller than the layer thickness, the layered medium has no significant influence on ground vibrations. However, when the penetration depth is larger than the layer thickness, the influence of the layered medium becomes more significant. The computed ground vibrations are finally compared with field measurements reported in the literature.