Methodology of Environmental Standardization for Natural Waters

Doklady Earth Sciences - This paper discusses sources of significant errors that occur in the course of determination of the primary environmental standard for natural waters: the maximum...     

Characterizing Colloidal Material in Natural Waters

Sampling has inherent uncertainties when applied tothe sub-micron fraction of natural waters.Processes of aggregation, biological activity andchemical transformation potentially effect changesimmediately after a sample is taken from the waterbody and there is no suitable method of samplestabilization. The size distribution and associatedphysical and chemical parameters of colloids in theaquatic environment can be effectively stable overshort periods of time (about two days under idealconditions, but frequently much shorter timeintervals). To achieve accurate representations of thesize distribution and associated colloidalcharacteristics in situ techniques are required,although adequate approximations may be obtained undersome circumstances if separation is done immediatelyafter sampling. This paper reviews the currentlyavailable strategies for separation and analysis ofcolloids from natural waters (primarily filtration andcentrifugation) and discusses their uses andlimitations, as well as potential uses of promisingtechniques (voltammetry, gels, field-flowfractionation, SPLITT). For small colloids, thetechniques of voltammetry, dialysis, DET and DGT maybe used to obtain in situ information. Forlarger colloids it is more difficult to performmeasurements in situ and a combination of rapidfractionation procedures, including filtration,field-flow fractionation and SPLITT, may still berequired.     

A Nonstratified Model for Natural Fractal Curves

The stratified structure of Koch curves limits their value as models of nonstratified curves typical in nature, which may nevertheless have statistically self-similar character. Richardson plots for basic and randomized Koch curves are marked by strong, scale-periodic disruptions, and compare poorly with the smoothly sloping, compact Richardson plots derived for some natural, irregular curves. These disruptions relate to the heirarchies of dominant element sizes created in the discrete steps of Koch curve construction, with element vertices acting as attractors for divider steps. We have developed a curve-generation algorithm that adds individual bend elements to a line segment in a nonstratified manner, explicitly following the self-similar limit relation of curve length (L) to added line segment length (r). Values that may be specified include curve fractal dimension (D) and bend element shape (angle of inclination for the added segments). The procedure allows combinations of fractal dimension and element shape, which encompass the range of D values encountered for natural fractal curves. The nonstratified construction method provides useful standard curves for testing and norming of geometric analysis methods commonly applied to complex natural features. In a preliminary test of a multisampling divider method algorithm, the resulting Richardson plots consistently diverge from linear form, and are likely to lead to an overapproximation of D value.     

ISORROPIA: A New Thermodynamic Equilibrium Model for Multiphase Multicomponent Inorganic Aerosols

A computationally efficient and rigorous thermodynamic model that predicts the physical state and composition of inorganic atmospheric aerosol is presented. One of the main features of the model is the implementation of mutual deliquescence of multicomponent salt particles, which lowers the deliquescence point of the aerosol phase.The model is used to examine the behavior of four types of tropospheric aerosol (marine, urban, remote continental and non-urban continental), and the results are compared with the predictions of two other models currently in use. The results of all three models were generally in good agreement. Differences were found primarily in the mutual deliquescence humidity regions, where the new model predicted the existence of water, and the other two did not. Differences in the behavior (speciation and water absorbing properties) between the aerosol types are pointed out. The new model also needed considerably less CPU time, and always shows stability and robust convergence.     

等离子体质谱法测定天然水中痕量元素

本文利用ICP-MS分析技术检出限低,可同时测定多元素,以及溶液进样等特点,建立了天然水中多种痕量元素分析的有效方法,研究了整个测定质量范围内的背景、干扰及其克服方法,讨论了水中Na、Mg、Ca等元素产生的基体效应对被测元素的影响。对含盐量较低的天然水样,可直接测定的痕量元素达50余种,测定限为0.x—xμg/L。高盐水样如海水、卤水等的测定,本文选择共沉淀法,以Fe(OH)_3为捕集剂,使被测元素与大量的碱金属、碱土金属基体分离。分离后可测40种痕量元素,测定限为0.0x—0.xμg/L。     

A Simple Limit Equilibrium Approach for Calculation of Ultimate Bearing Capacity of Shallow Foundations on Two-Layered Granular Soils

The bearing capacity of shallow foundations in a non-homogeneous soil profile has been a challenging task in geotechnical engineering. In this paper, a limit equilibrium method is used for calculating bearing capacity factors of shallow foundations constructed on a two-layered granular soil profile. The main objective has been to determine the ultimate bearing capacity computed from equivalent bearing capacity factors N_q and N_γ and comparing that with numerical analysis using finite element methods. It will be shown that the data obtained form the developed method are well comparable with those obtained from FE approach, specially when the difference between shear strength parameters of layers is low which is a practical case for sedimentary soil profiles and also for artificially compacted soils. A computer program has been developed to investigate the influence of various parameters on bearing capacity factors.     

自然河流中污染物排放的一种远区计算模型

建立了一个适合于自然河流中污染物排放的远区二维深度平均计算模型,此模型采用了自然河流中的大尺度湍流模拟理论,在离散过程中采用了上风格式及Peaceman-Rachford交替格式和Douglas交替格式,并应用于国内多条大、中、小型河流的污染物排放计算中,取得了广泛的成功。     

Chemical Characterisation of Natural Ilmenite: A Possible New Reference Material

Seven ilmenite (FeTiO₃) megacrysts derived from alnöite pipes (Island of Malaita, Solomon Islands) were characterised for their major and trace element compositions in relation to their potential use as secondary reference materials for in situ microanalysis. Abundances of thirteen trace elements obtained by laser ablation ICP‐MS analyses (using the NIST SRM 610 glass reference material) were compared with those determined by solution‐mode ICP‐MS measurements, and these indicated good agreement for most elements. The accuracy of the LA‐ICP‐MS protocol employed here was also assessed by repeated analysis of MPI‐DING international glass reference materials ML3B‐G and KL2‐G. Several of the Malaitan ilmenite megacrysts exhibited discrepancies between laser ablation and solution‐mode ICP‐MS analyses, primarily attributed to the presence of a titano‐magnetite exsolution phase (at the grain boundaries), which were incorporated solely in the solution‐mode runs. Element abundances obtained by LA‐ICP‐MS for three of the ilmenite megacrysts (CRN63E, CRN63H and CRN63K) investigated here had RSD (2s) values of < 20% and therefore can be considered as working values for reference purposes during routine LA‐ICP‐MS analyses of ilmenite.     

A Quaternary Solution Model for White Micas Based on Natural Coexisting Phengite-Paragonite Pairs

A thermodynamic model for the quaternary white mica solid solutionwith end-members muscovite–Mg-celadonite–paragonite–Fe-celadonite(Ms–MgCel–Pg–FeCel) is presented. The interactionenergies for the MgCel–Pg join, the FeCel–Pg joinand the ternary interactions were obtained from natural coexistingphengite–paragonite pairs. Phengite–paragonite pairswere selected based on the criteria that their chemical compositionsmay be represented as a linear combination of the model end-membercompositions and that the respective formation conditions (350–650°C,4–21 kbar) are accurately known. Previously publishedexcess free energy expressions were used for the Ms–Pg,Ms–MgCel and Ms–FeCel binaries. The suggested mixingmodel was tested by calculating multicomponent equilibrium phasediagrams. This proved to be particularly well suited to reproducecompositional variations of white micas from amphibolite-faciesmetapelites. KEY WORDS: white mica; solution model; equilibrium phase diagrams     

Geological and Geophysical Conditions for Potential Natural Gas Hydrate Resources in Southern South China Sea Waters

The water depth in Nansha(南沙) waters,which is located in the southern South China Sea,varies from 200 to 2 500 m,with a deep-water(>500 m) area of 500 000 km2.In this region,there are many depositional basins with various structural features,prone to the accumulation of organic material.The temperature and pressure conditions in the deep-water environment are suitable for the preservation of gas hydrate.At several sites,we have recognized bottom-simulating reflectors(BSRs) from seismic data.Regional geology...     

A Model Study on the Summertime Distribution of River Waters in Long Island Sound

Long Island Sound (LIS), a large urban estuary in the northeastern USA, receives freshwater from many rivers along its northern shore. The size of these rivers varies widely in terms of basin area and discharge. The Regional Ocean Modeling System (ROMS) was applied with conservative passive tracers to identify the distribution, mixing, freshwater residence times, and storm response for all of LIS’s river systems during the summer of 2013. A watershed model was applied to overcome the lack of adequate river discharge observations for coastal watersheds. The Connecticut River was the largest contributor to riverine freshwater throughout the estuary despite its entry point near the mouth. The Connecticut River strengthened bulk stratification in the eastern LIS the most but acted to weaken stratification near the mouths of other rivers and in far western LIS by freshening waters at depth. The Housatonic and Hudson Rivers had the strongest influence on stratification in central and western LIS, respectively. Smaller coastal rivers were the most influential in strengthening stratification near the southwestern Connecticut shoreline. The influence of small coastal rivers was amplified after a major storm due to shorter storm response times relative to the larger rivers. Overall, river water was close to a well-mixed state throughout LIS, but more stratified near river mouths. Freshwater residence time estimates, meanwhile, indicated monthly to multi-seasonal time scales (43 to 180 days) and grew longer with greater distance from the LIS mouth.     

论氢化物迁移成矿机制──兼论钒钛磁铁矿成矿的化学模式

论述了氢化物的形成条件及其物理化学特性。探讨了岩浆中钛、铁、钒、磷元素的迁移富集机制。建立了钒钛磁铁矿成矿的化学模式。     

电感耦合等离子体质谱法测定含气天然矿泉水中的铬

含气天然矿泉水含有高浓度的HCO;和CO2,其中元素Cr的浓度在电感耦合等离子体光谱(ICP-AES)的检出限附近甚至更低,应用电感耦合等离子体质谱(ICP-MS)测定又容易形成多原子离子40 Ar12C,对52 Cr的测定形成干扰,致使ICP-MS不能直接准确测定含气天然矿泉水中的Cr元素.本文对水样进行前处理,加热煮沸2 min后放置至室温,加入硝酸调节水样酸度为5％,促进HCO3-与H+反应生成大量的CO2迅速释放出来,消除了40Ar12C对52Cr产生的质谱干扰,实现了ICP-MS能够直接准确分析Cr的含量,方法检出限为0.23 ng/mL,加标回收率为92.3％～93.7％,相对标准偏差(RSD)小于10％.此方法简单实用,精确度和准确度能够满足天然矿泉水分析测试的要求,还可同时测定此批前处理水样中的锌铜砷镉铅等痕量元素.     

自然水体采集的生物膜上铁、锰氧化物的萃取分离

采用选择性萃取分离技术对自然水体采集的生物膜上铁、锰氧化物进行萃取分离研究,考察该技术的适用性。参考人工培养生物膜的萃取方法,分别用NH₂OH·HCl和Na₂S₂O₄为萃取剂选择性萃取生物膜上的锰氧化物和铁、锰氧化物。实验中分别依次只改变萃取剂浓度、萃取液酸度或萃取时间,保持其它两个因素不变,分别考察这三个因素对萃取效果的影响,从中选出对铁、锰氧化物萃取率高而对有机质影响小的条件为最佳条件。用选定的最佳条件对不同时间和地点采集的生物膜进行萃取,发现对目的组分的萃取率可达70.8%~94.6%,而对非目的组分的影响很小（3.3%~11.0%）,满足萃取分离的要求。这说明选择性萃取技术可以广泛应用于自然水体采集的生物膜上铁、锰氧化物的萃取分离。     

天然水镁石纤维的化学松解技术

研究了不同表面活性剂对不同等级水镁石纤维的松解效果，通过对纤维悬浮液叩解度、粘度、纤维表面Zeta电位、纤维混凝土强度等的研究，并经扫描电镜分析，证明了化学松解工艺对水镁石纤维具有较好地劈分作用。表面活性剂种类及用量对纤维的叩解度、纤维的表面电位、悬浮液粘度均有影响，对不同等级纤维的影响有差异。随表面活性剂用量增加，纤维的叩解度、纤维表面的负电荷量、悬浮液的粘度一般均呈增加趋势。经过化学分散试验，水镁石纤维得到了较好松解，纤维直径由微米级下降至纳米级。将水镁石纤维应用于混凝土，抗折强度随纤维叩解度的增加而提高，说明纤维的化学分散有利于纤维对混凝土增强作用的发挥。     

锂改性蒙脱石矿物中锂的化学状态研究

采用XRD、IR、XPS等测试方法,对锂改性蒙脱石矿物中锂 的化学状态进行分析,发现锂改性过程中,Li+离子不仅与蒙脱石层间吸附阳离子进行交 换,还能置换蒙脱石晶格八面体中的阳离子和进入间隙位置。Li+离子是以三种化学状态 存在于蒙脱石晶格结构中。     

联合机制下黏土垫层多离子扩散模型

扩散是工程领域中的一种重要现象,尤其是针对填埋场底部的压实黏土垫层。扩散过程受多种因素影响,如离子种类、离子价态和离子浓度等,因此建立准确的扩散模型对填埋场垫层系统设计和评估具有极其重要的意义。引入简化的Guntelberg活度系数表示真实溶液与理想溶液浓度值的偏差,采用化学势和扩散势共同表征多离子扩散的驱动力,并考虑黏土介质特有的半透膜性能对离子扩散规律的影响,建立了复杂机制联合作用下多组分并存时离子在黏土垫层中的扩散模型。采用多物理场仿真软件COMSOL Multiphysics对所建扩散模型进行数值求解,结果表明,黏土半透膜效应、溶液非理想性和扩散势均显著影响多离子扩散行为,考虑黏土半透膜效应及溶液非理想性条件下,多离子扩散进程明显减缓,考虑扩散势时,阳离子扩散速度显著提高。复杂机制联合作用下,多离子扩散规律并非单一影响机制的简单叠加,各机制之间相互制约共同影响多离子扩散行为。     

硅酸盐体系的化学平衡:(2)反应热力学

通过具体的应用实例,系统介绍了在矿物材料学研究中硅酸盐体系的多相平衡反应热力学的基本原理。对硅酸盐体系的典型多相平衡反应进行了热力学计算,包括:(1)微晶玻璃制备过程中的硅酸盐熔融反应;(2)霞石正长岩和高铝粉煤灰利用技术中的硅酸盐烧结反应;(3)S iO2-CaO-H2O体系和KA lS i3O8-CaO-H2O体系雪硅钙石、硬硅钙石的水热晶化反应;(4)高铝粉煤灰和霞石正长岩烧结产物的溶解反应;(5)Na[A l(OH)4]-A l(OH)3-H2O体系和Na2SO4-Ca(OH)2-H2O体系中α-A l(OH)3和CaSO4.2H2O的析晶反应。研究成果可望对矿物材料制备实验方案设计、工业生产过程优化及改进产品性能提供理论指导,同时为同类材料学研究提供借鉴。     

硅酸盐体系的化学平衡:(3)反应动力学

通过具体实例,简要介绍了矿物材料学研究中有关反应动力学研究的基本原理,给出了对硅酸盐体系若干典型过程的反应动力学研究结果,包括:(1)高铝粉煤灰-Na2CO3体系的中温烧结反应和钾长石-石膏-碳酸钙体系钾长石的热分解反应;(2)KA lS i3O8-Ca(OH)2-H2O体系钾长石水热分解-雪硅钙石晶化反应;(3)S iO2-A l2O3-CaO体系微晶玻璃的β硅灰石晶化反应;(4)13X微孔分子筛和MCM-41介孔分子筛对Hg2+的吸附反应。反应动力学研究成果可望对矿物材料制备实验方案优化、工业生产过程的条件控制以及改进矿物材料性能提供理论指导。     

地球化学平衡的理论和计算

本文系统地回顾了多相组分化学平衡的理论基础和计算方法，重点分析了当今流行的平衡常数法和自由能量小法的异同，证明了这些方法在原则上的同一性同时也证明了反应平衡常数和物种自由能之间的可互换怀，并指出了互换的方法。