二氧化硅水溶物种与热力学性质

系统综述了热液流体中溶解ＳｉＯ２存在形式的研究成果，指出溶解ＳｉＯ２在天然条件下主要呈真溶液迁移，其形式为Ｈ４ＳｉＯ４或Ｓｉ（ＯＨ）４·２Ｈ２Ｏ及其它水合数的单硅酸和多硅酸；在适宜的条件下，Ｈ３ＳｉＯ－４、ＮａＨ３ＳｉＯ０４、Ｓｉ（ＯＨ）４ＳＯ２－４、（Ｋ，Ｎａ）Ｓｉ（ＯＨ）０５或硅的有机配合物将成为主要的溶解物种。最后，给出了有关上述水溶物种的热力学平衡常数     

Heterogeneous Equilibria in Saturated Aqueous Solutions of Uranophane

Heterogeneous equilibria in the system Ca(HSiUO₆)₂ · 5H2O_(c)–aqueous solution were studied over broad ranges of pH, ionic strength, and ionic composition of the solution, and the pH range of stability of Ca uranyl silicate is determined. Hydrolysis products of Ca uranyl silicate are identified, and their solubility is determined. The equilibrium constant of the dissolution reaction and the standard Gibbs function of formation of Ca(HSiUO₆)₂ · 5H₂O are calculated from experimental data, and solubility curves of uranophane and equilibrium speciation diagrams for U(VI), Si(IV), and Ca(II) in coexisting aqueous solutions and solid phases are calculated.     

水悬浮液中硅的测定

本方法使用德国耶拿分析仪器股份公司的AAS novAA原子吸收光谱仪,断续流动注射SFS和50mm燃烧头刮板;AAS contrAA高分辨率连续光源火焰原子吸收光谱仪;测定水悬浮液中硅,并对两仪器的测定结果进行对比。     

水悬浮液中硅的测定

本方法使用德国耶拿分析仪器股份公司的AASnovAA(原子吸收光谱仪,断续流动注射SFS和50 mm燃烧头刮板;AAS contrAA高分辨率连续光源火焰原子吸收光谱仪;测定水悬浮液中硅,并对两仪器的测定结果进行对比。1样品制备为保证悬浮液样品均匀,将盛装悬浮液的容器封好后置于超声波水浴中10 min,然后立即将约0.5 g样品转移至50 mL容量瓶中,用1 g/L KCl(水溶液)定容至刻度线。各样品在测定前要充分摇匀。另外,要留意Si浓度的降低(1 h后约减少14%)。2仪器工作条件设定原子吸收光谱仪的工作条件:波长251.6 nm,狭缝0.2 nm,火焰类型N2O/C2H2,燃气流量25     

高温高压下流体中电解质活度系数的确定

高温高压下流体中电解质的活度系数在地球化学领域有着广泛的应用。本实验测量了100—500℃、0．11—12GPa下0．01mol／L KCl溶液的电导率,并利用Hueckel方程由实验确定的摩尔电导和极限摩尔电导计算出了KCl的平均摩尔活度系数。平均摩尔活度系数随温度升高而减小,随压力升高而增大,而在高温高压下随温度压力的升高几乎保持恒定。     

中国首次北极科学考察沿线气溶胶可溶性成分的分析

中国首次北极科学考察沿线采集的大气气溶胶样品可溶性成分分析表明,大气气溶胶的平均载量为195neq·m^-3,Na⁺和Cl^-的贡献为0%,NH₄⁺和SO₄^2-的贡献为27%,nssSO₄^2-对SO₄^2-的贡献为8%.气溶胶中阴、阳离子总量基本相当,大气环境呈中性.气溶胶中可溶性成分具有较强的纬度变化特征.根据离子的变化态势可将离子分为3大类,即1)Na⁺,Cl^-,SO₄^2-,K⁺,Mg²⁺,Ca²⁺;2)NH₄⁺,NO₃^-;3)MSA.Na⁺和Cl^-具有较好的线性关系,Cl^-/Na⁺的当量浓度比为1.01,小于其在海水中的比值1.1.NH₄⁺和NO₃^-的浓度随纬度的增加呈现减少的趋势,说明在低纬度近海岸地区人类活动的污染相当强烈.MSA的浓度在白令海区出现高值,与Shemya(52°N,174°E)站夏季浓度1.79±0.83neq·m^-3(170±79ng·m^-3)相当.通过与不同海区夏季释放DMS的通量对比,进一步证明了低温有利于DMS向MSA的转化.     

中国第二次北极科学考察沿线气溶胶成分分析

对2003年7月15~9月28日间中国第二次北极科学考察沿线所采集的气溶胶样品进行分析,获得了Na⁺、NH₄⁺ 、Ca²⁺、Cl^-、MSA、SO₄^2- 等11种离子的浓度数据(文中使用当量浓度).根据相关分析, 可将11种离子分为3类: 海盐源离子, 包括Na⁺、Mg²⁺、K⁺、Ca²⁺、Cl^-、SO₄^2-; 人为源, 包括NH₄⁺ 、NO₃^-; 其它源, 包括 CH₃COO^-、MSA、C₂O₄^2-. 气溶胶以海盐气溶胶为主, Cl^-、Na⁺ 离子分别是阴阳离子中含量最大的离子, (Na⁺ +Cl^-)对气溶胶载量(所测定的阴阳离子的总和)的贡献平均为60.2%, 占气溶胶总量的一半以上. NH₄⁺ /SO₄^2- 的比值的平均为0.45, 根据当地的大气环境和气溶胶的离子平衡, 认为气溶胶样品中NH₄⁺ 和 SO₄^2- 主要是以 NH4HSO4的形式结合. 根据考察沿线 NO₃^- 浓度的变化, 把考察沿线大致分为3个区: 日本海区, 中值为15.2 neq·m^-3; 鄂霍次克海及白令海区, 中值为1.8 neq·m^-3; 北冰洋区, 其浓度较低, 中值为0.4 neq·m^-3. 考察沿线白令海是MSA的高产区.     

Complexation of Pb(II) by Chloride Ions in Aqueous Solutions

Lead chloride formation constants at 25°C were derived from analysis of previous spectrophotometrically generated observations of lead speciation in a variety of aqueous solutions (HClO₄–HCl and NaCl–NaClO₄ mixtures, and solutions of MgCl₂ and CaCl₂). Specific interaction theory analysis of these formation constants produced coherent estimates of (a) PbCl⁺, \textPbCl₂⁰ {\text{PbCl}}_{2}^{0} , and PbCl₃⁻ formation constants at zero ionic strength, and (b) well-defined depictions of the dependence of these formation constants on ionic strength. Accompanying examination of a recent IUPAC critical assessment of lead formation constants, in conjunction with the spectrophotometrically generated formation constants presented in this study, revealed significant differences among various subsets of the IUPAC critically selected data. It was found that these differences could be substantially reduced through reanalysis of the formation constant data of one of the subsets. The resulting revised lead chloride formation constants are in good agreement with the formation constants derived from the earlier spectrophotometrically generated data. Combining these data sets provides an improved characterization of lead chloride complexation over a wide range of ionic strengths:

修饰电极测定土壤沉积物中各赋存状态砷

介绍了一种通过微分脉冲阳极溶出伏安法测定砷含量的方法，改进了金膜修饰电极的制备方法，并讨论了影响电极稳定的各种因素以及测定的最佳条件。在选定条件下，砷的溶出电流大小与其溶液中的浓度(0．01—1．00μg／L)呈线性关系(相关系数为0．9986)，砷的检出限为3．0ng／g。该方法测定结果与原子荧光测定结果相符，且方法已成功地用于山西省大同地区土壤沉积物中不同赋存状态砷含量的测定，各赋存状态砷的加和与总量测定基本相符。     

发射光谱法快速测定银锡铜铅锌钼铍

使用两台摄谱仪同时接收光谱,以K2S2O7、NaF、Al2O3为缓冲剂,Ge、Sb为内标,测定化探样品中7项元素,检出限(μg／g)分别是：Ag0．02,Sn0．5,Cu 1,Pb 2,Zn 10,Mo 0．2,Be 0．5;精密度(RSD,n=20)在2．9％～16．8％。采用国家一级标准物质验证方法可靠性,测定结果与标准值一致。     

邻菲啰啉光度法测定高岭土中可溶铁和非可溶铁

高岭土中铁的赋存状态和含量影响其白度和增白效果,因此快速准确地测定高岭土中不同种类的铁含量具有实际应用意义。高岭土中自由铁和结构铁定量分析困难,为此本文将高岭土中的铁分为可溶铁和非可溶铁两类。高岭土经盐酸酸溶处理后溶液中的铁含量为可溶铁含量,经氢氧化钠碱熔处理后溶液中的铁含量为总铁含量,非可溶铁含量由总铁含量减去可溶铁含量计算得出。采用邻菲啰啉光度法测定溶液中的铁含量,该方法的相对标准偏差小于5%,加样回收率范围在95%～105%,最低检测含量为1.06μg/g。高岭土中的其他元素对铁的测定均没有干扰。所测得的可溶铁为大部分自由铁和少数结构铁。通过对高岭土中的可溶铁进行定量分析,可得知漂白工艺中可除去的最大铁含量。     

Kinetics of Disproportionation of Inorganic Polysulfides in Undersaturated Aqueous Solutions at Environmentally Relevant Conditions

The rate of the reversible homogeneous disproportionation of polysulfides was studied by following the optical absorbance of polysulfide solutions in a continuous plug flow reactor equipped with an on-line photometric detector. In order to avoid heterogeneous slow reactions involving sulfur colloids or precipitate, the reaction was initiated by an abrupt pH change from an undersaturated solution containing predominantly tetrasulfide species to a pH where pentasulfide is the dominant species. The disproportionation was found to follow first order reversible reaction dynamics. At environmentally relevant conditions the characteristic time of the disproportionation reaction is of the order of 10 s. This characteristic time implies that necessary conditions for speciation of the different polysulfide species by chromatography or another separation and subsequent quantification scheme should be of the order of 1 s.     

有效储层物性下限方法的研究现状和发展方向

有效储层物性下限是评价储层储量最有效的方法,目前确定有效储层物性下限值的主要参数为储层的孔隙度、渗透率、含水饱和度参数。因储层物性受多种因素控制,导致不同地区、同一地区的不同时间段其物性下限均不同。目前确定物性下限值的方法包括压汞实验法、分布函数曲线法、核磁共振法、含油产状法等。每种方法均有其利弊,采用综合评价方法是未来确定有效储层物性下限的发展方向。     

地质调查样品中有机氯农药分析存在的困难和解决方法

9种有机氯农药(六氯苯、α-HCH、β-HCH、γ-HCH、δ-HCH、p,p′-DDE、p,p′-DDD、o,p′-DDT和p,p′-DDT)是国土资源地质大调查项目中水和土壤样品必测的有机污染物。有机氯农药自身结构和性质的特殊性以及地质调查样品的差异性,在采用气相色谱电子捕获检测器(GC-ECD)分析有机氯农药过程中仍然存在许多困难。文章结合大量地质调查样品中有机氯农药分析的实践经验,从溶剂与待测物响应值的关系、基质效应的表现、样品前处理以及仪器日常维护四个方面,介绍了针对不同样品和分析要求正确选择进样溶剂、判断和解决基质效应,并通过良好的仪器日常维护习惯确保地质调查样品中有机氯农药检测灵敏度达到要求。     

气体(CH4、H2S、CO2等)在水溶液中的溶解度模型

本文介绍一个通过状态方程和特定粒子相互作用理论建立起来的气体在水溶液中的溶解度模型,用以计算气体(CH4、H2S、CO2)在纯水和含盐水溶液中的溶解度、流体包裹体的均一条件、成矿热液沸腾、流体不混溶性、水合物形成条件、CO2地质储藏量等.该模型不仅重现了上百套实验数据(约8000多个数据点),而且具有很强的外延能力.因此适用宽广的温度、压力和盐度范围(CH4:273～523K,1～2000bar,0～6m;H2S:273～500K,0～200bar,O～6m;CO2:273～533K,0～2000bar,0～4.5m),而且精度高、形式简洁.由于使用状态方程和特定粒子相互作用理论相结合的方法,这一模型在无需实验数据的情况下能够拓展到诸如海水和地下热卤水等更为复杂的体系.该模型在国际上得到日益广泛的应用,已被许多国家的同行用以多方面的研究工作,如计算CH4、H2S和CO2气体在水、卤水和海水等天然水溶液不同温度、压力和盐度条件下的溶解度(即水溶液中最大允许的气体含量),分析矿物流体包裹体的PVTX条件(根据包裹体中气体的总含量和均一温度,用该模型就会很方便得到均一化压力,在此基础上还可以迸一步通过状态方程得到密度和等容线)、计算成矿流体的不混溶性或沸腾点、计算CO2地质储藏量、实验校正等方面.相关研究可进行在线计算:www.geochem-model.     

离子对色谱测定碱性样品溶液中铬的方法研究

提出了两种测定碱性样品溶液中铬的离子对色谱方法,第一方法将碱性溶液用Ｈ３ＰＯ４中和,流动相采用含有１５ｍｍｏｌ／ＬＮａ２ＳＯ４的１ｍｍｏｌ／Ｌ四丁基氢氧化铵溶液;第二种方法将碱性溶液用ＨＣｌ中和,流动相采用含有２．５ｍｍｏｌ／Ｌ辛胺和１０ｍｍｏｌ／ＬＮａＳＯ４的ψ＝６％的乙腈溶液。     

Examination and Refinement of the Determination of Aqueous Hydrogen Sulfide by the Methylene Blue Method

The accurate and precise measurement of total sulfide has been of major interest for well over a century. The most commonly used method involves the formation of a methylene blue?Csulfide complex and spectrophotometric measurement of its concentration. The study presented herein compares the two most commonly used methods as outlined in Standard Methods for the Examination of Water and Wastewater (in APHA, Standard methods for the examination of water and wastewater, Washington, 1960) and by Cline (Limnol Oceanogr 14:454?C458, 1969). In addition, this study clarifies the existing confusion of Cline??s reagent preparation procedure, as it is apparent that various interpretations exist among research groups regarding reagent preparation. After evaluating both methods with respect to precision and accuracy, detection limit, sample storage time, and ease of use, the method outlined in Cline was determined to be superior. Furthermore, we suggest that the reagent concentration has to be optimized depending on the range of sulfide concentrations to increase the accuracy and precision of the method.     

用线性自由能关系预测金属络合物的热力学性质

Sverjensky与Molling提出的线性自由能关系是根据金属阳离子的热力学性质来预测等结构系列中固体相的标准生成自由能。本文研究结果证实,水溶液中金属络合物与简单金属阳离子之间也存在类似的相关关系,预测值与实验值的差异通常小于1．5kcal／mol或小于一个log单位,这一线性自由能关系对于预测自然环境中重金属的水溶物种的配分、迁移和毒性具有非常重要的应用价值。     

连续光源火焰原子吸收光谱法测定水悬浮液中的硅

用连续光源火焰原子吸收光谱法测定水悬浮液中的硅。为保证悬浮液样品均匀,应将约0.5 g样品盛装容器封好后超声水浴10 min,然后立即转移至50 mL容量瓶中,用1 g/L KCl溶液(蒸馏水中)定容至刻度。各样品在测定前要充分摇匀。另外要留意Si 浓度的降低(1 h 后约减少14%)。     

Determination of the Concentration of Carbonic Species in Natural Waters: Results from a World‐Wide Proficiency Test

The results of an international interlaboratory proficiency test for the determination of carbonic species are presented. Eight laboratories analysed twelve water samples (four synthetic waters, one lake water, four geothermal waters, one seawater and two petroleum waters) by two methods: (a) individual laboratory analytical procedure and (b) acid–base titration curves in tabular form following a standardised protocol. In case (b), the concentrations of carbonic species were calculated by the organiser using the (1) Hydrologists' method, (2) Geochemists' method and/or (3) initial pH and total alkalinity method. For synthetic waters, the averaged % trueness and precision of measurement of the two methods were (trueness = 7.6, precision = 9.4) and (9.0, 3.4) for total alkalinity, and (6.6, 31.0) and (7.8, 6.1) for carbonic alkalinity, respectively. This indicates that the total alkalinity calculation procedure is in general correct in the individual laboratory method, but the carbonic alkalinity calculation procedure has serious problems. The measurements of total alkalinity for lake and seawaters were in agreement in both the methods; however, the individual laboratory measurement method for geothermal and petroleum waters was conceptually incorrect. Thus, the analytical procedures for the determination of carbonic species were reviewed. To apply the Hydrologists' and/or Geochemists' methods, the location of NaHCO₃EP and H₂CO₃EP is necessary, even for samples with pH lower than that of NaHCO₃EP, and a backward titration curve after complete removal of CO₂ must be performed. The initial pH and total alkalinity method is appropriate where a complete analysis of species that contribute to the alkalinity is known.