Isotopes and geochemistry in a managed aquifer recharge scheme: a case study of fresh water injection at the Damascus University Campus,Syria

A combination of stable isotopes (¹⁸O and ²H) and hydrochemistry has been applied to investigate storage processes in relation to aquifer storage and recovery (ASR) of the shallow alluvial Quaternary aquifer in Damascus basin. The stored water, entirely taken from the Figeh springs during flood periods, was injected in a single well having a brackish groundwater. Water samples were collected from four observation wells drilled in the Damascus University Campus (DUC) site during a 3‐year period (2006–2008). The injectant water, which deviates in its chemical and isotopic signatures from that of the ambient groundwater, shows that the stored water plume remains within close proximity to the injection well (IW) (<≈ 100 m). Thus, only two wells (W13 and W14) located at a distance less than 80 m from the injection point were affected by this injection. The observation wells located at longer distances from the IW (≈145 m and ≈ 600 m for wells W15 and WHz, respectively) were completely unaffected by the injection. Although most of the chemical and isotopic parameters usefully reflected the mixing process that occurs between the injectant water and ambient groundwater, the stable isotope (¹⁸O) and chloride (Cl⁻) were the most sensitive parameters that quickly reflect this signature. Using a simple mass balance, the calculated proportion of injectant water reaching the well W13 was in the range of 50–90%. This proportion was even lower (30–55%) in the case of well W14. Although the drought event prevailing during this study did not much help to inject further amounts of water, higher than the injected volume (0·2416 M m³) and also not favourable to better evaluate the fate and subsurface hydrological processes, these findings offer encouragement to continue the ASR activities, as an alternative way for better management of water resources in this basin facing intensive problems. Copyright © 2010 John Wiley & Sons, Ltd.     

Analysis of high-resolution spectra of mildly metal-poor stars I. Spectral data and equivalent widths

A number of high resolution and high signal-to-noise ratio spectra of mildly metal-poor stars were obtained with the coudé echelle spectrograph attached to the 2.16m telescope at Xinglong Observation Base of Beijing Astronomical Observatory. The spectra of seven mildly metal-poor stars were processed with the MIDAS software package, and the equivalent widths of their spectral lines were measured. The measured equivalent widths together with an error analysis are presented.     

Factors controlling the chemical evolution of travertine‐depositing rivers of the Barkly karst,northern Australia

Groundwaters feeding travertine‐depositing rivers of the northeastern segment of the Barkly karst (NW Queensland, Australia) are of comparable chemical composition, allowing a detailed investigation of how the rate of downstream chemical evolution varies from river to river. The discharge, pH, temperature, conductivity and major‐ion concentrations of five rivers were determined by standard field and laboratory techniques. The results show that each river experiences similar patterns of downstream chemical evolution, with CO₂ outgassing driving the waters to high levels of calcite supersaturation, which in turn leads to widespread calcium carbonate deposition. However, the rate at which the waters evolve, measured as the loss of CaCO₃ per kilometre, varies from river to river, and depends primarily upon discharge at the time of sampling and stream gradient. For example, Louie Creek (Q = 0·11 m³ s^?1) and Carl Creek (Q = 0·50 m³ s^?1) have identical stream gradients, but the loss of CaCO₃ per kilometre for Louie Creek is twice that of Carl Creek. The Gregory River (Q = 3·07 m³ s^?1), O'Shanassy River (Q = 0·57 m³ s^?1) and Lawn Hill Creek (Q = 0·72 m³ s^?1) have very similar gradients, but the rate of hydrochemical evolution of the Gregory River is significantly less than either of the other two systems. The results have major implications for travertine deposition: the stream reach required for waters to evolve to critical levels of calcite supersaturation will, all others things being equal, increase with increasing discharge, and the length of reach over which travertine is deposited will also increase with increasing discharge. This implies that fossil travertine deposits preserved well downstream of modern deposition limits are likely to have been formed under higher discharge regimes. Copyright © 2002 John Wiley & Sons, Ltd.     

常州市地下水化学特征与成因分析

常州市是长江三角洲地区典型的工业化城市,多年来的快速发展对地下水环境产生了系列影响,地下水化学组分受到天然条件和人为活动的双重因素控制,现状地下水化学成因和影响因素亟需深入研究。本文在地下水赋存条件分析的基础上,综合采用统计分析、离子比值、主成分分析法对常州各层地下水化学特征和成因开展分析。结果表明,区域潜水水化学类型以HCO₃^-—Ca²⁺·Mg²⁺、HCO₃^-—Ca²⁺和HCO₃^-·Cl^-—Na⁺·Ca²⁺型为主,第Ⅰ承压水以HCO₃^-—Na⁺·Ca²⁺和HCO₃^-—Ca²⁺型为主、第Ⅱ承压水以HCO₃^-—Na⁺     

黄河三角洲浅层地下水盐分来源及咸化过程研究

黄河三角洲地下水咸化已成为区域最突出的生态环境问题之一。识别地下水补给及盐分来源是有效控制和改善地下水咸化问题的关键。本研究采集了研究区浅层地下水、地表水和海水等不同类型水样,利用离子比、Piper三线图、吉布斯图等方法对八大离子浓度、δD和δ¹⁸O 组成、Br和Sr 浓度等进行地下水补给研究与盐分来源辨析。结果表明:(1)黄河三角洲浅层地下水以总溶解性固体(TDS)为338 g/L的咸水为主,地下水水化学类型较为单一,主要为Cl-Na型。(2)三角洲区域地下水以大气降水补给为主,并且在补给过程中经历了不同程度的蒸发作用的影响,黄河现行流路区域地下水主要来源于河水侧渗补给,但浅层地下水含水层水平渗透性较差限制了黄河侧渗补给范围。(3)海洋是黄河三角洲浅层地下水盐分的主要来源,黄河现行流路区域及近岸地下水盐分来源于海水混合,三角洲北部刁口河等古河道区域地下水盐分主要来源于海相蒸发盐淋滤溶解。     

我国北方新生代玄武岩地下水化学特征及其成因——以河北省张北县为例

为了进一步了解我国北方新生代玄武岩地下水的赋存规律和形成演化机理,以河北省张北县玄武岩地下水为研究对象,在野外采集地下水样、测定水化学和同位素组成的基础上,利用统计分析、离子比例系数、氢氧同位素、反向地球化学模拟等方法,对区内玄武岩地下水的水化学形成机制进行了研究。结果表明:沿地下水径流方向,研究区内玄武岩地下水中多数离子质量浓度呈现增大趋势,补给区的地下水化学类型以HCO₃-Ca·Mg为主,TDS质量浓度多小于500mg/L,排泄区地下水中阴离子以Cl^-和SO₄^2-为主,阳离子以Na⁺为主,TDS质量浓度多大于1 400mg/L;研究区地下水补给来源为当地大气降水;硅铝酸盐、岩盐、硫酸盐的风化溶解是地下水中离子的主要来源;溶滤作用、阳离子交替吸附作用和农业施肥等人类活动影响是控制地下水化学形成的主要作用。     

Generating non-stationary random fields of auto-correlated,normally distributed CPT profile by matrix decomposition method

This paper emphasises the true realisation of Cone Penetration Test (CPT) profiles considering non-stationary nature of the data. Formulation of stationary random field theory has been modified and adapted to non-stationary state in order to take into account the mean and variance variability for soil properties. Multi-variance correlation matrix along with the Cholesky decomposition technique was employed to produce realisations of non-homogenous and non-stationary random fields of CPT profiles. A piecewise and segmental data realisation according to the lithology and site class specifications acquired directly from CPT data is adopted in this study so as to render an accurate data simulation. For validation of proposed method 8 CPT test profiles collected from Urmia Lake site have been introduced and simulated by the stationary and non-stationary algorithms. The mean correlation coefficient between the actual CPT data profiles and related realisations along with some other important statistical parameters and their coefficients of variation strongly demonstrate that non-stationary random field generation technique gives quite better accuracy, by comparison to the conventional stationary random field generation scheme.     

改进角度纹理特征提取高分辨率遥感影像带状道路

针对目前高分辨率遥感影像的道路自动提取算法研究中的不足,该文提出了一种基于并行角度纹理特征的半自动道路提取算法:用户输入完成道路中心线上的起始点、道路方向、道路宽度等初始化工作,利用并行角度纹理特征获取道路前进方向,用抛物线参数方程构建道路轨迹模型来预测道路轨迹点,使用角度纹理特征值构建的紧质度系数和抛物线的曲率变化来约束道路轨迹点,验证失败则转入手工跟踪;往复执行以提取道路中心线。试验证明,本算法是一种稳健的道路半自动提取算法。     

基于三维激光扫描数据的地铁隧道断面测量

地铁主体施工完毕后为了对线路进行调线调坡,需要对地铁隧道进行断面测量,三维激光扫描与常规测量方法相比具有非接触式测量,可高密度采集空间三维点云数据等特点,为地铁断面测量提供了新的途径。本文基于Leica Scanstation 2扫描仪分析了三维激光扫描点云数据采集步骤和数据处理流程,阐述了基于点云数据的地铁断面测量方法,分析了三维激光扫描技术在隧道断面测量中应用的可行性。研究结果表明,这种高密度、高精度的隧道断面能够满足地铁调线调坡等方面的技术要求。     

确定风廓线雷达功率谱噪声功率方法

风廓线雷达以测风为主要目的设计,没有充分考虑强度的定量测量。如果能够实现强度定量测量将大大扩展风廓线雷达的应用范围。首要的扩展应用就是可以获取雨滴谱分布、解决降水定量测量准确性问题。若实现强度定量测量,需要解决的一个关键技术问题是如何由其功率谱数据准确计算噪声功率。该文根据风廓线雷达功率谱估计方法、依据噪声频域统计特性,提出了一种计算风廓线雷达功率谱噪声功率的方法,并利用风廓线雷达实测功率谱数据进行检验。检验结果表明:即便在有降水或存在地物时,该方法仍可以准确、快速分辨出噪声功率谱, 且客观有效。