The role of surface and sub-surface runoff processes in controlling cation export from a wetland watershed

Water and cation budgets were calculated for two sub-basins within a small low relief watershed in South-Central Ontario during a period of ephemeral runoff which was initiated by spring snow melt. The hydrology of one (upland) sub-basin was strongly influenced by seasonal fluctuations in the level of regional ground water. Saturated contributing areas formed in low lying regions adjacent to the stream channel where the water table rose to the surface, and stream discharge was a mixture of ground water and saturation overland flow. In the second sub-basin a wetland provided a large and spatially less variable saturated contributing area. Clay soils underlying the wetland resulted in a shallow perched water table, poorly drained and highly organic soils, and greatly reduced inputs of regional ground water. Stream discharge was largely the result of surface runoff from the wetland and adjacent areas of saturated soil.Inter-basin variations in water export were by far greater than variations in stream chemistry. As a result, inter-basin variations in cation export strongly reflected variations in water export over the time interval in which the majority of a given ion was lost from the watershed. Spatial differences in water export were least at the onset of runoff when basin saturation was greatest and overland flow made large contributions to the discharge from both sub-basins. Potassium and hydrogen had high concentrations at this time which caused these ions to show only small spatial differences in export. With decreases in the areal extent of soil saturation, and increases in the storage capacity of the wetland, the hydrologic contrast between sub-basins increased. Greater water loss from the upland area resulted from a greater discharge of regional ground water, and a more rapid expansion of the saturated contributing areas during storm events. Calcium, magnesium, and sodium concentrations increased steadily during the first 3 weeks of runoff, so that the peak export of these cations occurred later in the runoff period at times of higher concentration, but lower and spatially more variable discharges. Consequently, spatial differences in the loss of these ions was great and favoured the upland sub-basin, since the majority of export occurred when the hydrologic contrast between sub-basins was largest.     

阳离子交换树脂吸附石墨炉原子吸收法测定海水中痕量铜、铅、镉

用阳离子交换树脂吸附石墨炉原子吸收法测定海水中痕量Cu,Pb,Cd。实验选定了最佳的测定条件。结果表明,在弱碱性条件下,Cu,Pb,Cd能同时被阳离子交换树脂定量吸附。方法的相对标准偏差<3﹪,样品加标回收率93﹪～102﹪,检出限分别为Cu 0.06μg/L,Pb 0.06μg/L,Cd 0.005μg/L。本法操作简便、快速、无干扰、无污染,已用于海水中铜、铅、镉的分析,取得了令人满意的结果。     

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     

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.     

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。