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1.
For the last 15 a, SKB (the Swedish Nuclear Fuel and Waste Management Company) has been using the Äspö Hard Rock Laboratory (HRL) as the main test site for the development of suitable tools and methods for the final disposal of spent nuclear fuel. Major achievements have been made in the development of a new groundwater modelling technique. The technique described in this paper is used within the ongoing site investigations of Forsmark and Simpevarp in Sweden. 相似文献
2.
Two sites on the east coast of Sweden (Forsmark and Laxemar/Simpevarp) are currently being investigated as potential geologic hosts for a deep repository isolating high-level nuclear waste. In this paper, a methodology for fracture mineral studies is suggested with focus on the variation in depth of the fresh/saline water interface and location of the redox front in the bedrock. The most commonly precipitated fracture minerals in crystalline rocks are chlorite, calcite, quartz, K-feldspar, Ca–Al-silicates like epidote, prehnite and laumontite, sulphides and Fe-oxides. Of these, calcite is the mineral best suited for palaeohydrological studies since it precipitates during a wide range of conditions including low-temperature conditions during the Pleistocene and Holocene epochs. Sulphides and Fe-oxides/hydroxides provide information on the position of the redox front. In order to carry out palaeohydrological studies, a number of prerequisites are required such as; high quality drill core material, geological knowledge of the sequence of fracture mineralizations; the post-glacial (Holocene) evolution in the area; high quality groundwater chemistry, including stable isotopes; and a conceptual model of the hydrogeochemistry that is to be tested. The choice of methods used here is based on the fact that both the Forsmark and Laxemar/Simpevarp sites are situated in Palaeoproterozoic crystalline rocks with reactivation of fractures over at least 1.5 Ga, and they have been exposed to glaciations/deglaciations and transgressions/regressions of the Baltic Sea during the Quaternary. This has resulted in a palaeohydrology with a range of groundwaters of quite different chemistry and stable isotopic composition. The suggested scheme for solving the variation in depth of the fresh/saline water interface focuses on fracture calcite. It includes a step-by-step procedure with;
- (1)
- Initial δ18O and δ13C, analyses and complementary petrographic studies of thin sections and crystal morphology followed by 相似文献
3.
This work, which was done within the Swedish nuclear waste management program, was carried out in order to increase the understanding of the mobility and fate of rare earth elements (REEs) in natural boreal waters in granitoidic terrain. Two areas were studied, Forsmark and Simpevarp, one of which will be selected as a site for spent nuclear fuel. The highest REE concentrations were found in the overburden groundwaters, in Simpevarp in particular (median ∑REE 52 μg/L), but also in Forsmark (median ∑REE 6.7 μg/L). The fractionation patterns in these waters were characterised by light REE (LREE) enrichment and negative Ce and Eu anomalies. In contrast, the surface waters had relatively low REE concentrations. They were characterised either by an increase in relative concentrations throughout the lanthanide series (Forsmark which has a carbonate-rich till) or flat patterns (Simpevarp with carbonate-poor till), and had negative Ce and Eu anomalies. In the bedrock groundwaters, the concentrations and fractionation patterns of REEs were entirely different from those in the overburden groundwaters. The median La concentrations were low (just above 0.1 μg/L in both areas), only in a few samples were the concentrations of several REEs (and in a couple of rare cases all REEs) above the detection limit, and there was an increase in the relative concentrations throughout the lanthanide series. In contrast to these large spatial variations, the temporal trends were characterised by small (or non existent) variations in REE-fractionation patterns but rather large variations in concentrations. The Visual MINTEQ speciation calculations predicted that all REEs in all waters were closely associated with dissolved organic matter, and not with carbonate. In the hydrochemical data for the overburden groundwater in particular, there was however a strong indication of association with inorganic colloids, which were not included in the speciation model. Overall the results showed that within a typical boreal granitoidic setting, overburden groundwaters are enriched in REEs, organic complexes are much more important than carbonate complexes, there is little evidence of significant mixing of REEs between different water types (surface, overburden, bedrock) and spatial variations are more extensive than temporal ones. 相似文献
4.
Steven Joyce Lee Hartley David Applegate Jaap Hoek Peter Jackson 《Hydrogeology Journal》2014,22(6):1233-1249
Forsmark in Sweden has been proposed as the site of a geological repository for spent high-level nuclear fuel, to be located at a depth of approximately 470 m in fractured crystalline rock. The safety assessment for the repository has required a multi-disciplinary approach to evaluate the impact of hydrogeological and hydrogeochemical conditions close to the repository and in a wider regional context. Assessing the consequences of potential radionuclide releases requires quantitative site-specific information concerning the details of groundwater flow on the scale of individual waste canister locations (1–10 m) as well as details of groundwater flow and composition on the scale of groundwater pathways between the facility and the surface (500 m to 5 km). The purpose of this article is to provide an illustration of multi-scale modeling techniques and the results obtained when combining aspects of local-scale flows in fractures around a potential contaminant source with regional-scale groundwater flow and transport subject to natural evolution of the system. The approach set out is novel, as it incorporates both different scales of model and different levels of detail, combining discrete fracture network and equivalent continuous porous medium representations of fractured bedrock. 相似文献
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Application of inverse modeling in a study of the hydrogeochemical evolution of karst groundwater in the Jinci Spring region,northern China 总被引：1，自引：0，他引：1
Zhenxing Jia Hongfei Zang Philip Hobbs Xiuqing Zheng Yongxin Xu Kai Wang 《Environmental Earth Sciences》2017,76(8):312
This study explores the hydrogeochemical evolution of karst groundwater in the Jinci Spring region, Shanxi Province, northern China. During 2015, karst groundwater samples collected from 24 sampling points along several profiles that follow the groundwater flow direction were subjected to hydrochemical analysis. Reaction paths and mineral phases for the hydrogeochemical modeling were determined based on the analysis results and in conjunction with the regional geology and hydrogeology. The PHREEQC hydrogeochemical modeling software was used to perform mass balance and reaction path modeling of the hydrogeochemical evolution of the spring region. The modeling results showed that from the recharge area through the runoff area to the drainage area, the hydrogeochemical processes occurring in the karst water vary widely between the northeastern, central, and southwestern parts of the spring region, and across the piedmont discharge area. Additionally, hydrodynamic fields and geological structures were found to have significant control over the hydrogeochemical reactions occurring within the spring region’s karst groundwater. 相似文献
7.
One of the great environmental problems of our age is the safe disposal of radioactive waste for geological time periods. Britain is currently investigating a potential site for underground burial of waste, near the Sellafield nuclear plant. Future leakage of radionuclides depends greatly on subsurface water flows; these must be understood from the past, to predict hydrogeology 104 –105 years into the future. We have taken information from the present-day, published by the government company Nirex, and used a finite-element steady-state fluid flow computer code to examine water flows in the subsurface. We find that flow directions at the planned Repository are persistently upwards, and that geologically significant flow rates could occur. How rates are particularly sensitive to uncertainties of rock permeability (conductivity) measurements made from site investigation boreholes. The hydrogeology at this site needs longer term investigation before a confident and credible prediction can be made. 相似文献
8.
Antonio González-Ramón Manuel López-Chicano Juan Carlos Rubio-Campos 《Environmental Earth Sciences》2012,67(3):923-937
A small karst aquifer of great structural complexity has been subjected to significant resource withdrawal over recent decades. This exploitation aroused social conflict due to the effect it has had on emblematic springs. This research has analysed piezometric data collected over the course of 12 years and the spatial hydrochemical data supplied by the main water points associated with it. The spatial and temporal evolution of the main chemical species in the groundwater and the hydrogeochemical processes affecting them have been studied, modelling them with the programme PHREEQC. These data suggest a complicated model of hydrogeological function with sectors storing water at different depths and connected to each other locally as determined by the geological structure. 相似文献
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天山北麓中段受构造控制,水文地质条件较为复杂.研究孔隙水水化学特征及苏打水（NaHCO3型）形成机制对了解天山北麓中段地下水水文地球化学过程与地质条件之间的联系具有重要意义.基于新疆天山北麓中段平原区209组地下水水样,结合地质条件,采用半变异函数模型、绝对主成分得分多元线性回归模型（PCA/APCS-MLR）剖析了潜水和承压水中水化学类型空间分布特征、地下水化学组分源贡献率、苏打水形成的地质条件控制因素以及水文地球化学作用.结果表明:山前倾斜平原潜水、冲积平原潜水和承压水分别以Na2SO4、NaHCO3和Na2SO4型水为主,其中苏打水分别占总水样的7.18%、14.83%、6.22%.承压水中Na+、HCO3-、TDS空间自相关性较强,潜水中Na+、HCO3-、TDS空间自相关性较弱,当水中TDS < 1 000 mg/L时更有利于NaHCO3型水的形成.溶滤-富集因子（F1）、外界输入因子（F2）、原生地质因子（F3）和地质环境因子（F4）对地下水中水化学指标的平均贡献率分别为29.44%、15.99%、7.70%和6.71%.苏打水形成过程不仅受控于矿物溶滤、阳离子交换、混合作用和脱硫酸作用等多种水文地球化学作用,还受到地质环境、地质构造及水文地质条件的影响. 相似文献
11.
The Simpevarp area is one of the alternative sites being considered for the deep geological disposal of high level radioactive waste in Sweden. In this paper, a coupled regional groundwater flow and reactive solute transport model of the Simpevarp area is presented that integrates current hydrogeological and hydrochemical data of the area. The model simulates the current hydrochemical pattern of the groundwater system in the area. To that aim, a conceptual hydrochemical model was developed in order to represent the dominant chemical processes. Groundwater flow conditions were reproduced by taking into account fluid-density-dependent groundwater flow and regional hydrogeologic boundary conditions. Reactive solute transport calculations were performed on the basis of the velocity field so obtained. The model was calibrated and sensitivity analyses were carried out in order to investigate the effects of heterogeneities of hydraulic conductivity in the subsurface medium. Results provided by the reactive transport model are in good agreement with much of the measured hydrochemical data. This paper emphasizes the appropriateness of the use of reactive solute transport models when water-rock interaction reactions are involved, and demonstrates what powerful tools they are for the interpretation of hydrogeological and hydrochemical data from site geological repository characterization programs, by providing a qualitative framework for data analysis and testing of conceptual assumptions in a process-oriented approach. 相似文献
12.
An investigation was conducted to assess the hydrogeochemical processes of an alluvial channel aquifer located in a typical Karoo Basin of Southern Africa. The investigation was aimed at identifying and describing the groundwater chemistry evolution and its contribution to the overall groundwater quality. X-ray fluorescent spectrometry (XRF) and X-ray diffractometry (XRD) analyses were performed on geological samples to identify and quantify the major element oxides and minerals. The study utilises the conventional Piper diagram, bivariate plots and PHREEQC hydrogeochemical model to analyse groundwater chemistry data obtained during the wet (February and May) and dry seasons (August and December) of 2011. The XRF and XRD results show that the channel deposits are dominated by SiO2 element oxides and quartz minerals, thus elevated concentrations of silicon (Si4+) were found in the groundwater. Dolomite and calcite minerals were also detected in the unconsolidated aquifer sediments. The detailed study of the alluvial aquifer system has shown that dissolution of dolomite and calcite minerals and ion exchange are the dominant hydrogeochemical processes influencing the groundwater quality. The groundwater evolves from Ca2+–Mg2+–HCO3 ? recharge water that goes through ion exchange with Na+ in the clay-silt sediment to give a Na+–HCO3 ? water type. The groundwater is supersaturated with respect to quartz, dolomite and calcite minerals. The study shows the potential usefulness of simple bivariate plots as a complimentary tool to the conventional methods for analyzing groundwater hydrogeochemical processes. 相似文献
13.
Owing to its five decades in the chemical industry, Estarreja is one of the most important industrial areas in Portugal. Intensive industrial activity along with both direct discharge of the effluents into natural water streams and uncontrolled waste disposal on the ground has, throughout the years, had strong impact on health and welfare. Recently an association between industry and local authorities was created — ERASE. The main goal for this association is to find, in co-operation with the Portuguese Environmental Ministry, a cost-effective solution to deal with the soil/sediments contamination and solid waste problem.
The ERASE association planned to build a landfill for both solid waste and contaminated soil/sediments disposal. In order to determine more accurately the volume of material to be disposed of in the landfill, a site investigation was carried out during September/November 1998. The site investigation consisted mainly of systematic soil sampling at shallow depths, both within the industrial area and along the natural water streams.
The site investigation results revealed high concentrations of toxic pollutants, mainly heavy metals (namely As, Hg, Pb and Zn), in the soil of the industrial area. Much higher concentrations were found in the sediments of the water streams, several kilometres away from the industrial complex (the pollution source area).
In most cases, concentration increases with depth, reaching groundwater. Therefore the site investigation programme carried out could not determine the full extent of the contamination. Consequently, further studies were strongly recommended, which should include a wider and deeper investigation area and groundwater sampling. 相似文献
14.
Karstic limestone formations in the Mediterranean basin are potential water resources that can meet a significant portion
of groundwater demand. Therefore, it is necessary to thoroughly study the hydrogeology and hydrogeochemistry of karstic mountain
regions. This paper presents a detailed hydrogeological and hydrogeochemical characterization of the Nif Mountain karstic
aquifer system in western Turkey, an important recharge source for the densely populated surrounding area. Based on the geological
and hydrogeological studies, four major aquifers were identified in the study area including the allochthonous limestone in
Bornova flysch, conglomerate-sandstone and clayey-limestone in Neogene series, and the Quaternary alluvium. Physicochemical
characteristics of groundwater were measured in situ, and samples were collected at 59 locations comprised of springs and
wells. Samples were analyzed for major ions, isotopic composition, arsenic, boron and heavy metals among other trace elements.
It was found that the hydrogeological structure is complex with many springs having a wide range of discharge rates. High-discharge
springs originate from allochthonous limestone units, whereas low-discharge springs are formed at the contacts with claystone
and limestone units. Using stable isotope analysis data, a δ18O-deuterium relationship was obtained that lies between the Mediterranean meteoric and mean global lines. Tritium analyses
showed that low-discharge springs originating from contact zones had longer circulation times compared to the high-discharge
karstic springs. Furthermore, hydrogeochemical data revealed that groundwater quality significantly deteriorated as water
moved from the mountain to the plains. Heavy metal, arsenic and boron concentrations were generally within drinking-water
quality standards with a few exceptions occurring in residential and industrial areas located at the foothills of the mountain.
Elevated arsenic concentrations were related to local geologic formations, which are likely to contain oxidized sulfite minerals
in claystones. It is concluded that Nif Mountain overall has a significant potential to provide high-quality water with a
safe yield of at least 50 million m3/year, which corresponds to about 28% of the mean annual inflow to the Tahtali reservoir, a major water resource for the city
of Izmir.
An erratum to this article can be found at 相似文献
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Patrik Vidstrand Sven Follin Jan-Olof Selroos Jens-Ove Näslund Ingvar Rhén 《Hydrogeology Journal》2013,21(1):239-255
On-going geological disposal programs for spent nuclear fuel have generated strong demands for investigation and characterization of deep-lying groundwater systems. Because of the long time scales for which radiological safety needs to be demonstrated in safety assessment applications, an analysis of the hydrogeological performance of the geosphere system during glacial climate conditions is needed. Groundwater flow at depth in crystalline rock during the passage of an ice-sheet margin is discussed based on performed groundwater-flow modeling of two bedrock sites, Forsmark and Laxemar, in the Fennoscandian Shield, Sweden. The modeled ice sheet mimics the Weichselian ice sheet during its last major advance and retreat over northern Europe. The paper elaborates and analyzes different choices of top boundary conditions at the ice sheet–subsurface interface (e.g. ice-sheet thickness and ice-margin velocity) and in the proglacial area (presence or lack of permafrost) and relates these choices to available groundwater-flow-model hydraulic output and prevailing conceptual hydrogeochemical models of the salinity evolution at the two sites. It is concluded that the choice of boundary conditions has a strong impact on results and that the studied sites behave differently for identical boundary conditions due to differences in their structural-hydraulic properties. 相似文献
17.
《Applied Geochemistry》1999,14(7):893-905
The hydrogeology of a vertical fracture zone at 70 m depth at the access tunnel to the Äspö Hard Rock Laboratory was monitored over 3 a for hydrochemical changes that could be effected by construction of a deep repository for high-level nuclear waste. Tunnel construction dramatically disturbed the hydrogeological system, but this provided an opportunity to integrate hydrogeochemical and hydrological evaluation of the zone. The objective of this study was to evaluate hydrogeochemical evolution, groundwater flow and surface water intrusion during the experiment using an integrated approach of geochemical mass-balance calculations and numerical flow simulations.The dilution of major ions was the dominant hydrochemical trend. However, HCO3 and SO4 showed significant enrichment. Increasing activity of 14C suggested that oxidation of organic C was the likely source of HCO3. Any mineral source dissolving during the experiment seemed insufficient to account for changes in SO4 and current intrusion of sea water was excluded according to the data. Cation exchange as well as minor calcite reactions in fractures were assumed probable in such temporary chemical conditions. Conservative two end-member mixing models with shallow groundwater in the zone and initial groundwater at tunnel level also assumed remarkable mass transfer (several mmol/l). Therefore a third SO4-rich end-member, a regional shallow groundwater type which may mix by lateral flow in the system, was tested. This was also expected from hydraulic measurements and preliminary flow simulations assuming homogeneity.Three end-member mixing calculations using Cl and SO4 as conservative tracers give a constant proportion of lateral water in all boreholes after 300 days, which is consistent with the steady state character of the flow field in the late part of the experiment. To predict reactions on plausible levels needs significant adjustments of initial and final waters, indicating uncertainties in the hydrochemical information of the fracture zone. In the flow simulations the transmissivities were selected so that the chemical mixing proportions would match simulated portions of flow as closely as possible. The simulated total recoveries (drawdowns) differ from the measurements mainly due to overly simple parametrisation of the transmissivity in the fracture zone. However, integrating hydrochemistry in flow modelling is considered encouraging in producing additional information of the heterogeneity of a flow structure. 相似文献
18.
以ETM+遥感数据为主要遥感信息源,应用遥感技术对喀喇昆仑山温泉地区进行1∶25万图幅的水文地质调查。根据地质体的影像特征并与前人地质填图结果对比,建立了遥感解译标志。重点对新生代地层及与水文地质有关的要素等进行解译,编制1∶25万新生代遥感解译图。根据遥感图像对研究区的第四纪沉积物的成因类型和分布范围、地貌特征及河流、湖泊、泉群、地下水溢出带、湿地等水文地质特征进行了研究。基于区内地下水形成环境的差异,地下水资源体系可以分为南部河谷冲积层地下水系统和北部内流湖盆地下水系统。总结地下水的分布特征认为,南部冲积层储水条件较为优越,且补给充分,其地下水与地表水构成一个统一的水资源系统;北部内流湖盆地区多为湖相沉积,受气象因素制约,山前巨大的冲洪积扇存在丰富的地下水外,地下水资源总体贫乏。遥感水文地质调查表明,遥感技术在高原区域填图与水文地质调查中具有高效率低成本的优点,可以在青藏高原水文地质调查中发挥重要作用。 相似文献
19.
高放废物处置库甘肃北山预选区地下水的形成 总被引：1，自引：0，他引：1
在高放废物处置库场地选择和性能评价中,水文地质特征是最重要的因素之一,地下水的形成则是水文地质研究中的首要问题。在水文地质、地下水化学、同位素、CFC、地下水动态等资料综合分析的基础上,探讨了高放废物处置库甘肃北山预选区地下水的形成问题。研究结果表明,北山地区地下水以赋存于变质岩、岩浆岩、碎屑岩、碳酸岩节理、裂隙中的基岩裂隙潜水为主,地下水化学成分具有明显的水平分带性特征,地下水动态类型主要为入渗—蒸发—径流型,结合地下水同位素和CFC 特征,认为区内地下水主要由当地大气降水入渗补给形成。浅部地下水主要由现代区内降水补给形成,而深部地下水则可能由地质历史时期降水补给形成。 相似文献
20.
Bibhash Nath Doris Stüben Sukumar Basu Mallik Debashis Chatterjee Laurent Charlet 《Applied Geochemistry》2008
The present study demonstrates the importance of hydrogeochemical characteristics (groundwater flow and recharge) of an aquifer in the release of As to groundwater. The study area (∼20 km2) is located in Chakdaha block, Nadia district, West Bengal, which hosts groundwaters of variable As content. The spatial distribution pattern of As is patchy with areas containing groundwater that is high in As (>200 μg L−1) found in close vicinity to low As (<50 μg L−1) groundwaters (within 100 m). The concentration of groundwater As is found to decrease with depth. In addition, the data shows that there is no conspicuous relationship between high groundwater As concentration and high groundwater abstraction, although the central cone of depression has enlarged over 2 a and is extending towards the SE of the study area. The river Hooghly, which forms the NW boundary of the study site, shows dual behaviour (effluent and influent during pre- and post-monsoon periods, respectively), complicating the site hydrogeology. The observed groundwater flow lines tend to be deflected away from the high As portion of the aquifer, indicating that groundwater movement is very sluggish in the As-rich area. This leads to a high residence time for this groundwater package, prolonging sediment–water interaction, and hence facilitating groundwater As release. 相似文献