Major ion chemistry of groundwater in the extreme arid region northwest China

The Ejina Basin, located in arid northwest China, is one of the most arid areas in the world. In recent years, rapid development has created a greater demand for water which is increasingly fulfilled by groundwater abstraction. Detailed knowledge of geochemical evolution of groundwater and water quality can improve the understanding of a hydrochemical system, and promote sustainable development and effective management of groundwater resources. To this end, a hydrochemical survey was conducted in the Ejina Basin in order to identify the major hydrochemical characteristics. The results of chemical analysis indicate that groundwater in the area is brackish. The major ions, TDS, and hydrochemical types of different areas are highly variable and show an obvious zonation from the recharge area to the discharge area. Saturation index (SI), calculated according to the ionic ration plot, indicates that the gypsum-halite dissolution reactions take place under the condition of the rock weathering to some extent, and evaporation is the dominant factor to determine the major ionic composition in the study area.     

Major Element Chemical Heterogeneity in Geo2 Olivine Microbeam Reference Material: A Spatial Approach to Quantifying Heterogeneity in Primary Reference Materials

A 270 spot‐analysis study was conducted across a large (ca. 1200 μm × 1200 μm) chip of Geo2 olivine from a commercially available GEO Mk2 block (P and H Developments 2016 , Standards for EPMA), which revealed an 8.7% relative range in FeO abundance. Interleaved and overlapping grids of different resolutions were measured sequentially to prove spatial patterns are not due to drift or other external sources of error. Results were mapped and interpolated using commercially available geographical information system software, such that composition could be predicted according to location with high accuracy. The simple, systematic zonation pattern observed demonstrates that useful‐sized regions of acceptable homogeneity do exist for some elements. This knowledge allows a user to target individual regions of a characterised chip for use as distinct measurement standards. As analysis times decrease and data sets grow, this approach may maximise laboratory efficiency by characterising large chips and extending time between conventional block repolish and coating, particularly in those cases where the avoidance of prior beam damage is a key concern.     

广饶县浅层地下水水化学演化分析研究

通过分析广饶县多年来的浅层地下水水质监测资料,研究总结了该区浅层地下水水化学类型及主要水化学组分的动态演化特征。研究表明,南部淡水区水质普遍有恶化趋势,4个监测点中有3个阴离子类型已经或已出现由HCO_3型转变为HCO3·Cl型的趋势,且矿化度、氯离子含量普遍有升高趋势,主要与浅层地下水降落漏斗的形成有关。     

武山台数据信息管理系统设计与实现

根据武山水化学综合地震台的具体情况，在微机汉字ＤＯＳ环境下利用ＦｏｘＢＡＳＥ＋２．１０关系型数据库成功开发了武山台数据信息管理系统。本系统全部采用Ｆｏｘｂａｓｅ＋数据库编写，主要用于地震台站的数据管理及各种报表的自动生成。程序采用自项向下，逐步求精方法设计，全部功能模块均采用下拉式窗口。程序设计中，最大限度地采用了容错处理。一年多的实际运行表明，系统操作简单，界面友好，容错功能完善，完全满足台站日常工作需要。     

山西奇村热水井水汞异常与地震

研究了奇村热水井水汞异常与山西境内地震的关系，发现奇村热水井水汞异常与山西境内Ｍ＞４．０地震有较好的对应关系。说明水汞是奇村热水井的映震灵敏的观测项目     

Deriving drainage networks and catchment boundaries: a new methodology combining digital elevation data and environmental characteristics

Digital data on the position and characteristics of river networks and catchments are important for the analysis of pressures and impacts on water resources. GIS tools allow for the combined analysis of digital elevation data and environmental parameters in order to derive this kind of information. This article presents a new approach making use of medium-resolution digital elevation data (250-m grid cell size) and information on climate, vegetation cover, terrain morphology, soils and lithology to derive river networks and catchments over extended areas.In general, methods to extract channel networks at small scale use a constant threshold for the critical contributing area, independent of widely varying landscape conditions. As a consequence, the resulting drainage network does not reflect the natural variability in drainage density. To overcome this limitation, a classification of the landscape is proposed. The various data available are analysed in an integrated approach in order to characterise the terrain with respect to its ability to develop lower or higher drainage densities, resulting in five landscape types. For each landscape type, the slope–area relationship is then derived and the critical contributing area is determined. In the subsequent channel extraction, a dedicated critical contributing area threshold is used for each landscape type.The described methodology has been developed and tested for the territory of Italy. Results have been validated comparing the derived data with river and catchment data sets from other sources and at varying scales. Good agreement both in terms of river superimposition and drainage density could be demonstrated.     

Hydrogeochemistry and cation-exchange processes in the coastal aquifer of Mar Del Plata,Argentina

The aquifer of Mar del Plata is unconfined and composed of silt and fine sand. The sand fraction is mainly quartz, potassium feldspars, chalcedony, and gypsum. Volcanic-glass shards (40–60%) dominate the silt fraction, and the clays are of the smectite and illite groups. Calcium carbonate, in caliche form, constitutes about 10–20% of the sediment. Groundwater flow is from west to east, and discharge is in the Atlantic Ocean. Because of overexploitation, the flow direction was reversed in a coastal belt about 3.5 km wide, and this has resulted in seawater intrusion. The groundwater is the CaHCO₃ type in the recharge zone, and becomes NaHCO₃ type towards the discharge area. Salinization by marine intrusion and seawater/fresh-water mixing produces an increase in the major-ion concentrations of the groundwater. The calcium content of the groundwater is higher and the sodium content is lower than those that would be expected if the mixing is considered as just the addition of seawater and fresh water in determined proportions without reactive processes taking place. Hydrogeochemical modeling was applied to the study of hydrogeochemical processes, mainly cation exchange, using the codes NETPATH and PHREEQM. Calcite and gypsum equilibrium, together with cation exchange, are the main hydrogeochemical processes. Cation-exchange capacity of the solid phase was determined by empirical calculations and experimental methods. The affinity order for the groundwater in contact with the aquifer matrix is Ca>Mg>Na in the regional-flow system, but the order is reversed in the salinization process. Reactive transport modeling using the code PHREEQM is useful for analyzing cation exchange in a marine-intrusion process. Electronic Publication     

Chemical Characterisation of Geological Raw Materials Used in Traditional Ceramics

A wide range of natural raw materials is used in the manufacture of traditional ceramic products such as ceramic tiles, frits, glazes and pigments. The chemical composition of these raw materials needs to be strictly controlled to assure end-product quality and enable the identification of the origin of defects caused by impurities or contamination. Six types of ceramic raw materials (silica sand, clays and kaolin, feldspars and related minerals, calcium and magnesium carbonates, sodium and calcium borates, and zirconium silicates) have been analysed in this study. X-ray fluorescence (XRF), potentiometry, coulometry and atomic absorption spectrometry (AAS) were used in this chemical characterisation. A methodology has been established for characterising each studied raw material, by identifying the chemical elements to be determined, selecting the most appropriate technique and validating each measurement. The reference materials used for validation were BCS CRM 267, 313/1, 393 and 388 (BAS), GBW 03103, GBW 07404, NIST SRM 181, 201a and 1835, Euronorm CRM 782-1 and Syenite SY-2. The results showed that most of the elements present in the geological samples used as traditional ceramic raw materials could be determined by XRF. The determination of light elements, such as lithium, fluorine and boron, is more suitably conducted by ICP-AES/AAS, potentiometry or potentiometry/ICP-AES respectively. Organic and inorganic carbon could be determined by coulometry. Inorganic carbon (CO₂) could also be determined by coulometry or by thermogravimetry, if samples did not contain clay minerals. Loss on ignition was always determined by gravimetry.     

Hydrochemical evolution and water quality along the groundwater flow path in the Sandıklı plain, Afyon, Turkey

 An unconfined aquifer system suggests an open system in the study area. Hydrochemical evolution is related to the flow path of groundwater. The groundwaters are divided into two hydrochemical facies in the study area, 1) Ca–Mg–HCO₃ and 2) Ca–Mg–SO₄HCO₃. Facies 1 has shallow (young) waters which dominate in recharge areas during rapid flow conditions, whereas facies 2 may show shallow and mixed waters which dominate intermediate or discharge areas during low flow conditions. Ionic concentrations, TDS, EC and water quality are related to groundwater residence time and groundwater types. The groundwaters in the plain are chemically potable and suitable for both domestic and agricultural purposes. Received: 20 May 1996 · Accepted: 30 July 1996