Acquisition de salinité et qualité des eaux d’une nappe profonde en Tunisie: approche statistique et géochimique     

Mohsen Ben Alaya  Thouraya Zemni  Ahmed Mamou  Fouad Zargouni 《水文科学杂志》2013,58(2):395-419

Abstract

The multi-layered Jeffara de Gabes aquifer system is greatly influenced by tectonics. This system is limited at the base and laterally by evaporite layers and has lateral contacts with the sebkhas (salt flats). The groundwater in this aquifer is characterized by high salinity (3–10 g L^-1). Multivariate statistical analysis and a geochemical approach were applied to determine the influence of the evaporite layers and sebkhas on the hydrochemical quality of the Jeffara de Gabes aquifer, and to understand the processes governing its salinity. According to these methods, and based in part on the Sr²⁺/Ca²⁺ ratio, it is demonstrated that the strong salinity of the groundwater is due to interactions between water and the evaporite layers that act as a substratum of this aquifer, as well as saltwater intrusion from the sebkhas. Moreover, the medium- to poor-quality groundwaters are characterized by geochemical interactions: cationic exchange and the precipitation/dissolution process of minerals in the aquifer formations.

Editeur Z.W. Kundzewicz

Citation Ben Alaya, M., Zemni, T., Mamou, A. et Zargouni, F., 2014. Acquisition de salinité et qualité des eaux d’une nappe profonde, Tunisie: approche statistique et géochimique. Hydrological Sciences Journal, 59 (2), 395–419.  相似文献   

Radially convergent groundwater flow in sloping terrain     

《水文科学杂志》2013,58(4):700-712

Abstract

The groundwater flow equation governing the elevation (h) of the steady-state phreatic surface in a sloping aquifer fed by constant recharge over a bi-circular sector is rhh′ ? r ² Bh′ + Pr ² ? PR ² = 0, where r is the radial coordinate, P is a constant involving recharge and aquifer properties, and B is the slope of the aquifer—bedrock boundary. The derived flow equation describes radially convergent flow through a sloping aquifer that discharges to a water body of fixed head. One important simplification is that in which the width of the bi-circular sector is constant, and the draining land becomes a rectangular aquifer. The bi-circular sector and rectangular-strip groundwater flow problems are solved in terms of implicit equations. The solutions for the steady-state phreatic surfaces depend on the ratio of recharge to hydraulic conductivity, the slope of the aquifer-bedrock, and the downstream constant-head boundary. Computational examples illustrate the application of the solutions.  相似文献   

典型隔水边界非稳定流承压含水层抽水试验研究     

郑玉萍  于强  解大可  韩晔  徐鸣  韦劲松 《地下水》2012,(2):11-13

隔水边界附近的承压含水层,即半无限区域的承压含水层参数的准确求取对于特定地段的地下水资源量计算具有重要意义。以高密市柴沟镇小于家庄抽水试验为例,详细阐述了隔水边界附近的承压含水层参数求取过程,并对结果进行较为详尽的讨论。  相似文献   

山东张宝庄铁矿水文地质特征研究     

邢业江  聂佩孝 《山东地质》2012,(4):30-32

张宝庄铁矿矿床位于当地侵蚀基准面以下,呈似层状,倾角多在45°以上,埋深20～888m。对矿区3个主要含水层及其之间的水力联系进行分析,这3个含水层分别为第四纪全新世冲洪积孔隙水含水层、基岩风化裂隙水含水层和泰山岩群变质岩构造裂隙水含水层,各含水层之间水力联系较弱。另外还研究了矿床充水因素、预测矿床正常涌水量和最大涌水量,在此基础上划分该矿区水文地质条件为中等类型。  相似文献   

澳大利亚Otway盆地二氧化碳地质封存示范工程介绍          下载免费PDF全文

张二勇 《水文地质工程地质》2012,39(2):131-138

澳大利亚Otway盆地二氧化碳地质封存示范工程是澳大利亚第一个完整的从源到汇的碳封存研究项目,也是碳封存领导论坛（CSLF）和国际能源总署（IEA）认可的二氧化碳地质封存国际合作项目,由澳大利亚CO2CRC牵头开展相关研究。项目封存场地位于澳大利亚维多利亚州的Otway盆地,分两个阶段进行。第一阶段,2004~2010年开展衰竭气田的二氧化碳地质封存研究,已向位于地下深处2000m的晚白垩系Waarre C粗砂岩地层灌注二氧化碳混合气体65000多吨,并成功实现构造圈闭封存,同时开展了地下水、土壤气体、大气、地球化学、地球物理等综合监测;第二阶段,2010 ~2015年开展地下咸水层封存二氧化碳的研究,将向位于地下1500m深处的晚白垩系Paaratte细砂岩咸水含水层注入10000t二氧化碳,实现二氧化碳毛细滞留圈闭封存,目前正在开展前期抽注试验。  相似文献   

季节性冻结-冻融期地中蒸渗计资料处理探讨   总被引：1，自引：1，他引：0       下载免费PDF全文

王政友 《水文地质工程地质》2012,39(1):13-18

本文针对地中蒸渗计在冻结-冻融期存在的问题,利用实验站冻土及土壤水分势能资料,探索了冻土层的发育及其水分运移规律,通过对亚砂土不同埋深及不同年度的地中蒸渗计资料处理,得出冻结期和冻融期地中蒸渗计资料的处理方法及其埋深临界值。这对准确利用冻结-冻融期地中蒸渗计资料具有重要的指导意义。  相似文献   

基于数值模拟探讨提高咸水层CO2 封存注入率的途径     

许雅琴  张可霓  王洋 《岩土力学》2012,33(12):3825-3832

咸水层CO2地质封存是减少大气中CO2排放量的有效途径。CO2注入率是衡量咸水层中CO2注入能力的有效因素,因此,研究注入速率的变化规律及提高的措施是很有工程价值的。在很多区域,地层的低渗透性限制了CO2的注入率。针对鄂尔多斯盆地的水文地质条件,通过数值模拟,探讨在低渗透性咸水层中提高CO2注入率的途径,包括改变储层中的盐度、采用水平井注入、增加注入井段的长度以及采取水力压裂等工程措施。其中改变储层中的盐度可通过在注入CO2前向储层中注入一定量的水来实现。模拟结果表明,这些方式可以有效地提高CO2注入率,其中水平井改造方式和水力压裂工程措施效果显著,盐度改造措施在地层初始含盐度较高时,会有更好的效果。研究结果可为鄂尔多斯盆地和类似地区的咸水层CO2地质封存项目提供参考。  相似文献   

深部咸水层二氧化碳地质储存场地选址储盖层评价   总被引：1，自引：0，他引：1  

刁玉杰  张森琦  郭建强  李旭峰  范基姣  贾小丰 《岩土力学》2012,33(8):2422-2428

深部咸水层CO2地质储存属于环保型工程项目,开展地质评价来确定良好的储盖层是实现CO2地质储存长期、有效、安全封存的首要前提。储层地质评价内容主要包括储层的物理性质及其注入能力等;盖层地质评价内容主要包括盖层发育特征及封闭能力等。在规划选址到工程选址的不同阶段,储盖层评价的内容和对象应根据不同阶段的目的依次提高精度和量化程度。通过国内深部咸水层CO2地质储存工程场地选址阶段划分,结合储盖层地质评价的主要内容,初步建立了储盖层适宜性评价指标及其分级标准,对国内深部咸水层CO2地质储存工程场地选址中的储盖层地质评价及适宜性评价工作具有一定的指导意义。  相似文献   

Provenance of chalk tesserae from Brading Roman Villa, Isle of Wight, UK     

Alison Tasker  Ian P. Wilkinson  Mark Williams 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(5):933-937

Thin section petrographical analysis of chalk tesserae at Brading Roman Villa, Isle of Wight, England, identifies a range of planktonic foraminifera and the calcareous algal cyst Pithonella that identify the Late Cenomanian Rotalipora cushmani Biozone (BGS Foraminiferal Biozones 4iii to 7). The local chalk crop to the north of the villa includes rocks of R. cushmani Biozone age, and indicates a likely local, rather than long distance, source for the tesserae. Microfossils provide a powerful tool for identifying the provenance of artefacts in Roman Britain.  相似文献   

Determination of arsenic concentration and distribution in the Floridan Aquifer System     

T. Pichler  R. Price  O. Lazareva  A. Dippold 《Journal of Geochemical Exploration》2011,111(3):84-96

Here we report on the different sampling strategies for almost seven years of sampling rocks/sediments for the determination of As within the Intermediate Aquifer System (IAS) and upper Floridan Aquifer System (FAS), a very large and productive limestone aquifer spanning from Georgia into Florida. In the FAS, As contamination has become a recurring problem during aquifer storage and recovery (ASR), particularly in central and south Florida.To investigate these phenomena, samples from solid drill cores and rock cuttings were collected from the Hawthorn Group, Suwannee Limestone, Ocala Limestone and Avon Park Formation. Samples were taken along drill cores and rock cuttings (referred to as ‘interval’ samples) or from particular drill core sections and rock cuttings (referred to as ‘targeted’ samples) likely to contain elevated concentrations of As as indicated by the presence of pyrite, hydrous ferric oxide, organic matter, clay minerals, fracture surfaces, and high permeable (moldic) zones.Arsenic was present in all of the stratigraphic units at low concentrations, close to the global average for As in limestone of 2.6 mg/kg. The highest As concentration was 69 mg/kg. In all units, however, the average bulk As concentration in the targeted samples was substantially higher than that in the interval samples. Based on direct spot measurements by electron microprobe and indirect calculations, pyrite was identified as the main source of As in the FAS. Concentrations in pyrite ranged from less than 100 mg/kg to more than 11,000 mg/kg. Because pyrite is heterogeneously distributed, both vertically and horizontally in the sampled stratigraphic units, the same was observed for the distribution of As. However, As concentrations generally decreased with depth, i.e., highest As values in the Hawthorn Group and lowest As values in the Ocala Limestone and Avon Park Formation. Compared to pyrite, other trace minerals contained much less As.The average As concentrations of the two types of sample media (solid cores and rock cuttings) were quite similar. These results indicate that if simply the average bulk rock As concentration of a geologic unit is the desired outcome of an investigation, either interval or targeted sampling of rock cuttings, seems to be sufficient. This is particularly important when time and money are a factor. This approach could work equally well for any other trace element. Structural sedimentary information, such as fractures, etc., is likely lost, however, when sampling rock cuttings. Thus, if this information is required, solid core samples need to be collected by hollow core diamond drilling.  相似文献