HYDROCHEMISTRY AS AN INDICATOR OF SUBGLACIAL DRAINAGE SYSTEM STRUCTURE: A COMPARISON OF ALPINE AND SUB-POLAR ENVIRONMENTS

The anion compositions (SO²₄, HCO⁻₃ and Cl⁻) of runoff from the Haut Glacier d'Arolla, Switzerland and Austre Brøggerbreen, Svalbard are compared to assess whether or not variations in water chemistry with discharge are consistent with current understanding of the subglacial drainage structure of warm- and polythermal-based glaciers. These glacial catchments have very different bedrocks and the subglacial drainage structures are also believed to be different, yet the range of anion concentrations show considerable overlap for SO²⁻₄ and HCO⁻₃. Concentrations of Cl⁻ are higher at Austre Brøggerbreen because of the maritime location of the glacier. Correcting SO²⁻₄ for the snowpack component reveals that the variation in non-snowpack SO²⁻₄ with discharge and with HCO⁻₃ is similar to that observed at the Haut Glacier d'Arolla. Hence, if we assume that the provenance of the non-snowpack SO²⁻₄ is the same in both glacial drainage systems, a distributed drainage system also contributes to runoff at Austre Brøggerbreen. We have no independent means of testing the assumption at present. The lower concentrations of non-snowpack SO²⁻₄ at Austre Brøggerbreen may suggest that a smaller proportion of runoff originates from a distributed drainage system than at the Haut Glacier d'Arolla.     

川西成都盐盆平落4井富钾硼溴浓卤水水化学同位素地球化学特征及形成机制

根据盐盆的演化历史，水化学组分Ｈ，Ｏ，Ｓ，Ｂ等同位素组成综合分析，该浓卤水具有海，陆相混合型卤水的特征，一些元素的富集是在成盐成卤晚期由外来卤水和地层水流入盐盆混合并溶解盐层，在蒸发条件下形成的。     

Effects of permafrost degradation on thermokarst lake hydrochemistry in the Qinghai-Tibet Plateau,China

Thermokarst lakes play a key role in the hydrological and biogeochemical cycles of permafrost regions. Current knowledge regarding the changes caused by permafrost degradation to the hydrochemistry of lakes in the Qinghai-Tibet Plateau (QTP) is limited. To address this gap, a systematic investigation of thermokarst lake water, suprapermafrost water, ground ice, and precipitation was conducted in the hinterland of the QTP. The thermokarst lake water in the QTP was identified to be of the Na-HCO₃-Cl type. The mean concentrations of HCO₃⁻ and Na⁺ were 281.8 mg L⁻¹ (146.0–546.2 mg L⁻¹) and 73.3 mg L⁻¹ (9.2–345.8 mg L⁻¹), respectively. The concentrations of Li⁺, NH₄⁺, K⁺, F⁻, NO₂⁻, and NO₃⁻ were relatively low. Freeze-out fractionation concentrated the dissolved solids within the lake water during winter, which was deeply deepened on lake depth and lake ice thickness. Owing to solute enrichment, the ground ice was characterized by high salinity. Conversely, repeated replenishment via precipitation led to lower solute concentrations in the ground ice near the permafrost table compared to that within the permafrost. Although lower solute concentration existed in precipitation, the soil leaching and saline ground ice melting processes enhanced the solute load in suprapermafrost water, which is considered an important water and solute resource in thermokarst lakes. The influencing mechanism of permafrost degradation on thermokarst lake hydrochemistry is presumably linked to: (1) the liberation of soluble materials sequestered in ground ice; (2) the increase of solutes in suprapermafrost water and soil pore water; and (3) the changes in lake morphometry. These results have major implications on the understanding of the effects of ground ice melting on ecosystem functions, biogeochemical processes, and energy balance in a rapidly changing climate.     

天津蓟县系雾迷山组地热流体水化学特征研究

蓟县系雾迷山组是天津地区主要开发利用的热储层之一。笔者基于区域地质资料,全面分析了天津地区蓟县系雾迷山组热储层的形成及分布特征,认为该层在天津的山区和平原区均有分布,具有分布连续稳定、沉积厚度大、裂隙发育、水质良好等特点。通过一系列的水化学资料及同位素资料分析,揭示了该热储层的水化学特征及其动态变化规律,进而阐明了地热流体的形成和运移特征。该层中的热流体其水化学类型主要受地下水径流排泄条件制约,由北部地区的HCO3-Ca·Mg型,逐步过度到南部地区的Cl·SO4-Na型,呈现由山前到盆地中心的水平分带性。     

Hydrogeochemical and Isotopic Study of Groundwater in a Semi-arid Region: Yeniceoba Plain (Cihanbeyli-KONYA), Central Anatolia,Turkey

Groundwater is the most important source of water supply in the Yeniceoba Plain in Central Anatolia,Turkey.An understanding of the geochemical evolution of groundwater is important for the sustainable development of water resources in this region.A hydrogeochemical investigation was conducted in the Plio-Quaternary aquifer system using stable isotopes(δ~(18)O andδD),tritium(~3H),major and minor elements(Ca,Na,K,Mg,Cl,SO_4,NO_3,HCO_3 and Br)in order to identify groundwater chemistry patterns and the processes affecting groundwater mineralization in this system.The chemical data reveal that the chemical composition of groundwater in this aquifer system is mainly controlled by rock/water interactions including dissolution of evaporitic minerals,weathering of silicates,precipitation/dissolution of carbonates,ion exchange,and evaporation.Based on the values of Cl/Br ratio(300 mg/l)in the Plio-Quaternary groundwater,dissolution of evaporitic minerals in aquifer contributes significantly to the high mineralization.The stable isotope analyses indicate that the groundwater in the system was influenced by evaporation of rainfall during infiltration.Low tritium values(generally1 tritium units)of groundwater reflect a minor contribution of recent recharge and groundwater residence times of more than three or four decades.     

基于矩形图的天然水化学分类和水化学规律研究

在论述Piper图和Durov图的基础上,推荐一种新的水化学图——矩形图,并详细叙述了矩形水化学图的划分原则和依据。通过银川平原地下水水化学资料分析,证实这种水化学图可用于确定地下水的水化学类型,并进行水文地球化学规律研究。     

Contribution to the study of thermal waters in Greece: chemical patterns and origin of thermal water in the thermal springs of Lesvos

The occurrence of thermal/spa waters on Lesvos Island is related to the presence of a major faulting system. Thermal waters are the result of mixing of meteoric and infiltrating seawater at great depth, and their total salinity depends on the percentage of seawater in their composition. According to the diagrams of main elements, trace elements and environmental isotopes, most of the components that determine the chemical composition of thermal waters such as sodium, chloride and sulphates originate from seawaters. On the other hand, the concentration of calcium, magnesium, boron, lithium, etc., was affected by water–rock interaction under high temperature conditions. Moving towards the surface, thermal waters may become polluted by influx of recent seawater, allowing their chemical composition to become similar to that of seawater. The thermal waters of Lesvos Island present relatively high concentrations of ammonia and redox sensitive metals because they are hosted in a reducing environment. They also exhibit low nitrate concentrations due to their mixture with recent fresh water. Finally, they show increased radon concentrations, ranging from 20 to 60 kBq m^?3 in the eastern and southern parts of the island, and about 230 kBq m^?3 in the north, in the area of Eftalou–Argenos. Copyright © 2007 John Wiley & Sons, Ltd.     

Using multivariate statistical techniques and geochemical modelling to identify factors controlling the evolution of groundwater chemistry in a typical transitional area between Taihang Mountains and North China Plain

Identifying the key factors controlling groundwater chemical evolution in mountain-plain transitional areas is crucial for the security of groundwater resources in both headwater basins and downstream plains. In this study, multivariate statistical techniques and geochemical modelling were used to analyse the groundwater chemical data from a typical headwater basin of the North China Plain. Groundwater samples were divided into three groups, which evolved from Group A with low mineralized Ca-HCO₃ water, through Group B with moderate mineralized Ca-SO₄-HCO₃ water, to Group C with highly saline Ca-SO₄ and Ca-Cl water. Water-rock interaction and nitrate contamination were mainly responsible for the variation in groundwater chemistry. Groundwater chemical compositions in Group A were mainly influenced by dissolution of carbonates and cation exchange, and suffered less nitrate contamination, closely relating to their locations in woodland and grassland with less pronounced human interference. Chemical evolution of groundwater in Groups B and C was gradually predominated by the dissolution of evaporites, reverse ion exchange, and anthropogenic factors. Additionally, the results of the inverse geochemical model showed that dedolomitization caused by gypsum dissolution, played a key role in the geochemical evolution from Group A to Group B. Heavy nitrate enrichment in most groundwater samples of Groups B and C was closely associated with the land-use patterns of farmland and residential areas. Apart from the high loads of chemical fertilizers in irrigation return flow as the main source for nitrate contamination, the stagnant zones, flood irrigation pattern, mine drainage, and groundwater-exploitation reduction program were also important contributors for such high mineralization and heavy NO₃⁻ contents in Group C. The important findings of this work not only provide the conceptual framework for the headwater basin but also have important implications for sustainable management of groundwater resources in other headwater basins of the North China Plain.     

粤东北贝岭地热田地热地质特征及水化学分析北大核心CSCD

粤东北地区拥有丰富的低温水热型地热资源。贝岭地热田位于河源深断裂北东端,具有优越的地热地质条件,地热田内施工的钻孔(ZK1~ZK5)均揭露到了热矿水,水温48.2~77.0℃。为了深入研究地热田内的水化学特征,通过运用系统的水文地球化学分析方法,得出研究区热矿水水化学类型为低矿化的HCO_(3)-Na型,SiO_(2)含量较高,可用作理疗矿泉水。研究区地下热矿水处于水岩作用的初级阶段,热矿水中的石英和玉髓溶解度已达平衡状态。使用石英温标进行热储估算,结果表明T_(石英)=116.0~150.1℃,平均地温梯度G=12.01℃/100 m,热储循环深度H=819.33~1103.26 m。本研究为今后该区的深部找热工作提供了一定的技术支撑。     

Characteristics of Hydrogen and Oxygen Isotopes and Noble Gas Isotopes in the Groundwater of Weishan, Wudalianchi, Northeast China

According to the hydrochemical characteristics, hydrogen and oxygen isotope characteristics and the ratio of noble gas isotopes of the sandstone aquifer and basalt aquifer, this study calculated the recharge temperature and residence time of groundwater in the Weishan area of Wudalianchi, also calculating the contribution of noble gas components from different sources to the samples. Based on the characteristics of hydrogen and oxygen isotopes and noble gases Xe and Ne, the recharge altitude and recharge temperature of the two aquifers were estimated, and the recharge temperature fitting with the NGT model as verified, the results showing that the main recharge altitude of groundwater in the region was 500–600 m, the recharge temperature being 2–7°C. Heeq and Heea of the samples have been simulated using the OD model, the content of radioactive 4He in the crust being obtained, the groundwater ages under the two conditions (closed condition and open condition) both being simulated. The results show that groundwater from the sandstone layer water is older than groundwater from the basalt layer. Hydrochemical characteristics and noble gas isotope ratios indicate that in the basalt aquifer and sandstone aquifer in the Weishan area, in addition to atmospheric and crustal helium, there is also an input of mantle-derived helium. The fault constitutes the uplift channel for groundwater containings mantle components, which results in the mantle source composition in water samples near the fault being much higher than those form non-fault areas.