离子色谱法测定温泉水中多种阴阳离子

在用离子色谱法测定温泉水样中F~-、Cl~-、Br~-、NO_2~-、NO_3~-、SO_4~(2-)、PO_4~(2-)等阴离子和Li~+、Na~+、K~+、Mg~(2+)、Ca~(2+)等阳离子过程中,研究了用油泵超声波池内脱气法处理H_2CO_3过饱和水样以排除HCO_3~-对阴离子检测干扰的方法.研究采用青岛普仁仪器有限公司生产的PIC-8型离子色谱仪,分离柱为TSK-GEL SuperIC-CationColumn(150 mm×4.5 mm)离子分离柱,以1.9 mmol/L碳酸钠-1.8mmol/L碳酸氢钠作为阴离子淋洗液,流量为1.5 Ml/min;以2 mmol/L HNO_3为阳离子淋洗液,流量为1.0 ml/min,测定了腾冲火山区叠水河、大滚锅两个温泉水中的阴阳离子的含量.研究结果表明:该方法简便、快速、准确可靠,可在火山和地震监测中推广使用.     

Low-temperature single-crystal Raman spectrum of pyrope

 The single-crystal polarized Raman spectra of synthetic pyrope, Mg₃Al₂Si₃O₁₂, were measured at room temperature and 5 K, as were the room-temperature unpolarized spectra of two natural pyrope-rich crystals. No major differences in the spectra between room temperature and 5 K are observed or are present between the synthetic and the natural crystals. The spectra are consistent with the proposal that the Mg cation is dynamically disordered and not statically distributed over subsites in the large triangular-dodecahedral E-site in pyrope. A low-energy band at about 135 cm⁻¹ softens and shows a large decrease in its line width with decreasing temperature. The presence of a weak, broad band at about 280 cm⁻¹ may be due to anharmonic effects, as could the one at 135 cm⁻¹. The latter is assigned to the rattling motion of Mg in pyrope in the plane of the longer Mg-O(4) bonds (Kolesov and Geiger 1998). The successful modeling of the anisotropic motion of the Mg cation in pyrope, which has an anharmonic character, provides a valuable test of the validity of empirical or semi-empirical lattice-dynamic calculations for silicates. Received: 10 May 1999 / Accepted: 10 April 2000     

青海省调整划定基本农田保护区存在的问题及其对策

介绍青海省基本农田保护区调整划定工作的实践经验,对存在的问题进行了初步分析和探讨,同时根据青海省基本农田保护区划定工作的现状,提出了相应的措施及对策。     

Rock mass characterization for the underground cavern design of Khiritharn pumped storage scheme

A general approach to rock engineering designing aspects adopted at the Khiritharn Pumped Storage Scheme is described. The scheme involves excavation of three large caverns and tunnels in jointed sandstone within a suture zone in Southeast Thailand. Geological condition and engineering properties of the sandstone were investigated. Strength and modulus properties of the intact rock were determined from laboratory tests and properties of rock mass were empirically estimated for the design analysis in the de.nite study stage on the basis of three rock mass classi.cation systems namely the Rock Mass Rating (RMR), Geological Strength Index (GSI) and a Japanese system (EPDC). While the GSI gives strength and modulus of deformation values slightly higher than the RMR classi.cation, the EPDC gives a lower value of modulus of deformation but comparable rock mass strength value for the level of con.ning pressures at the depth of the cavern excavation. The results of stress analysis and loosening wedge analysis for the cavern excavations suggest favorable excavation condition.     

Fe2+ -邻二氮菲树脂相分光光度法测定痕量铁的研究

基于三乙醇胺-盐酸介质中,Fe2 与邻二氮菲形成的阳离子配合物被强酸型阳离子交换树脂吸附富集,使树脂显桔红色,据此建立了测定痕量铁的树脂相分光光度法,并讨论了适宜的实验条件。方法的检出限为1.65×10-2μg/mL,ε=9.44×104L·mol-1·cm-1。用于茶叶、余甘中痕量铁的测定,结果令人满意。     

Particle Size Distributions of Clay-rich Sediments and Pure Clay Minerals: A Comparison of Grain Size Analysis with Sedimentation Field-Flow Fractionation

Two clay-rich coastal sediment samples have been characterised together with three pure clays identified as major components of the sediment samples. The mineralogy of the sediments was determined by X-ray diffraction, and their bulk properties measured (organic carbon content, leachable iron and manganese, surface area and cation exchange capacity). A simple approach is used to model the properties of the sediments from those of their pure clay components. Good agreement is found for cation exchange capacity and specific surface area indicating that the clay minerals are the most important constituents influencing the sediments' surface properties. Particle size distributions were assessed by conventional grain size analysis, and also by Sedimentation Field-Flow Fractionation (SedFFF). These two approaches yield sharply differing size distributions; in particular, conventional grainsize analysis indicates a much greater proportion of submicron particles. Similar results are obtained from analysis of pure clays. The most likely reason for this is artifacts introduced in the unavoidable 1 m prefractionation used for SedFFF.     

中国城乡建设占用耕地的时空格局及形成机制

描绘了1996-2006年间中国城乡建设用地增长及其占用耕地的时空特征,探讨了城乡建设占用耕地的驱动机制。研究发现：人口流动为主的城镇化模式导致农业转移人口在城乡“两头占地”,这是中国城乡建设用地持续扩张的主要根源;各类开发区的设立和扩张都以占用耕地为主,对城乡建设占用耕地的贡献超过一半;而城市和镇的扩张速度更慢、土地来源更为多元。实证结果表明,投资和产出增长的差异性对城乡建设及其耕地占用的时空格局起到了关键作用;中西部地区的基础设施建设占用了大量耕地,但对区域经济发展和人口集聚的带动作用有限;以开发区为载体的产业集聚发展模式有利于中西部地区的土地集约利用和耕地保护,而东部沿海地区的省级开发区则容易成为地方政府的圈地运动。土地集约利用和耕地保护政策应重点解决农业转移人口城乡同时占地的问题,发挥城镇化的节地效应,并强化政策的区域差异性和针对性。     

Farmer Identity in Multifunctional Landscapes: using a collective identity construct to explore the nature and impact of occupational identity

The use of multifunctionalism to conceptualise contemporary rural landscapes has focused attention on the increased extent and impact of non-farmers in traditionally agriculture-based rural communities. Typologies of rural landholders have been developed as part of that research effort. However, those typologies are not grounded in established theory, including collective identity theory that could provide an important foundation for the study of occupational identity. Indeed, most quantitative studies may be flawed in drawing on only one of the seven elements contributing to collective identity. This paper examines the efficacy of relying on self-declared occupational identity through the analysis of rural landholder survey data in an Australian region. Tests for expected relationships between self-declared identity of farmer/non-farmer and social and farming variables expected to be correlated with occupation, such as property size, profitability, hours worked on- and off-property, enterprise type and membership of farming-related local organisations found that the expected relationships existed. It seems that self-declared occupational identity is a valid and cost-effective way to explore occupational identity amongst rural landholders. Collective identity, however, is complex and it is unlikely that important research questions can be adequately explored without a more holistic approach to the study of farmer identity in multifunctional landscapes. The paper concludes with a discussion of the potential benefits of moving beyond self-declared occupation to include other elements in the collective identity construct.     

高温改性锌铁尖晶石的晶体化学与磁性研究

尖晶石型矿物因其阳离子在氧四面体和氧八面体中所占比例的不同而分为正尖晶石、反尖晶石和过渡的无序结构尖晶石。本文以微米级锌铁正尖晶石(Zn Fe2O4)为初始研究对象,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线吸收精细结构谱(XAFS)、差热-热重分析(DTA-TGA)、磁性测试(M-H、ZFC-FC)等矿物学、热学和磁学测试手段综合分析了温度对其阳离子配位的影响。结果显示,随着温度的升高,原正尖晶石结构中四面体的ZnⅡ会逐渐与八面体中的FeⅢ发生交换,910℃左右时阳离子的交换速率出现最大值,并在1 200℃加热24 h后达到热动力学平衡,此时晶胞参数a从8.440 7减小到了8.437 2;同时尼尔温度(TN)由13 K升到了27 K,反映了由反铁磁性向亚铁磁性过渡的磁结构变化。本文研究认为,由粒径不同带来的体系能量的差异是造成微米级Zn Fe2O4在高温下阳离子交换行为与纳米级颗粒截然相反的根本原因。     

膨润土的交换性阳离子组成及其属性分析

系统考察了我国不同产地膨润土的可交换阳离子组成、pH值以及碱性系数，根据层间阳离子组成对各地膨润土进行了属性分析。研究表明，所选矿区膨润土大多是钙基土，矿样的层间阳离子组成存在差异。讨论了膨润土层间阳离子种类、pH值、碱性系数以及其属性之间的关系。对比不同属性划分法后发现，离子比率法是一种全面反映膨润土层间阳离子种类及数量的属性分类方法。