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1.
在高放废物处置库场地选择和性能评价中,地下水化学特征是最重要的因素之一。文中以野外水文地球化学调查资料为基础,应用水文地球综合分析方法和地下水地球化学模拟技术,探讨中国高放废物处置库甘肃北山野马泉预选区地下水化学特征、时空分布规律及水岩作用机理。主要结论是:野马泉地区地下水以咸水为主, 具有高矿化的特征,水化学类型以Cl·SO4 Na和SO4·Cl Na型为主,pH值大多在7~8 之间;地下水化学成分显示出明显的分带特征;地下水对石盐和石膏欠饱和,对黄铁矿以及铝硅酸盐过饱和;方解石、钠长石在补给区地下水中呈不饱和状态,在排泄区地下水中呈饱和状态。由水岩作用模拟可知,沿水流路径地下水溶解岩石中的钠长石、黑云母、石盐等矿物,溶解二氧化碳,沉淀析出方解石、伊利石和萤石等矿物;发生明显地下水蒸发作用、二氧化碳溶解作用和Ca2+/ Na+离子交换作用, 说明溶滤、沉淀、离子交换和蒸发浓缩作用是区内地下水化学行为的控制因素。  相似文献   

2.
This paper reveals the geochemical processes of dissolution, precipitation and cation exchange that took place during water–rock interaction between water seepages through the Tannur Dam. The Schoeller diagram indicates that there are three major water types originating during water–rock interaction. The first water type is characterized by low salinity that ranges from 1,300 to 2,800 µs/cm, which represents the reservoir water and the water in the right side of the central gallery. The second water type is in the left side of the central gallery, which exhibits medium salinity that reaches about 4,400 µs/cm. The third water type is characterized by very high salinity that reaches a value of around 8,500 µs/cm and represents the water in the right existing adit. The increase of salinity can be explained due to the dissolution of carbonate and sulfate minerals that form the matrix of the foundation and the abutment rocks, and the dissolution of the grout curtain, which is composed of cement and bentonite. Hydrogeochemical modeling, using a computer code PHREEQC, was used to obtain the saturation indices of specific mineral phases, which might be related to interaction with water seepages, and to identify the chemical species of the dissolved ions. The thermodynamic calculations indicate that most of the water samples were undersaturated with respect to gypsum, anhydrite and halite, and were saturated and/or supersaturated with respect to calcite and dolomite. Ca(HCO3)2 is the primary water type, as a result of dissolution of carbonate minerals such as calcite and dolomite prevailing at the dam site. However, cation-exchange processes are responsible for the formation of the Na2SO4 water type from the CaSO4 type that formed due to the dissolution of gypsum.  相似文献   

3.
The present paper investigates hydrochemical processes and water quality in the Mornag aquifer in NE Tunisia. Groundwater samples were collected during a field campaign, and were analysed for major and trace elements. The collected waters have a chemical facies rich in Ca2+, Na+ and Cl-. Piper diagram shows a progressive increase in chloride ions along with increasing salinity. Saturation indexes calculated by using PHREEQC (USGS) show that the Mornag waters are slightly saturated with respect to carbonates (calcite and dolomite), while undersaturated with respect to gypsum, halite and other evaporitic minerals. The current composition of waters takes place via dissolution of halite and Ca-sulfates, where the increase in calcium is partially balanced by possible calcite precipitation. The relevant recorded pollutant is nitrate, which was likely dispersed from agricultural soils, while heavy metals were generally far below values of pollution thresholds, indicating no influence by mining activity.  相似文献   

4.
利用小昌马河流域上游大雪山老虎沟冰雪融水及下游昌马洪积扇区地下水的稳定同位素和水化学资料, 对流域稳定同位素和水化学的组分特征和季节变化进行了分析. 结果表明: 小昌马河流域内从上游冰雪融水区到下游昌马洪积扇地下水排泄区矿化度不断增高, 水化学类型由HCO3-Mg-Ca过渡到HCO3-SO4-Ca-Mg; 上游冰雪融水与下游地下水δ18O的季节变化基本一致, 洪积扇区地下水来源于冰雪融水的补给. 水文地球化学模型模拟显示地下水形成过程中水岩作用以析出方解石, 吸收二氧化碳, 溶解石膏、 岩盐和绿泥石等为主要特征, 溶蚀的含盐矿物使地下水中氯化物、 硫酸根和钠离子含量升高, 地下水水质恶化. 同位素和水化学证据均揭示了小昌马河流域地表水-地下水的化学环境转化关系.  相似文献   

5.
Sabkhas are ubiquitous geomorphic features in eastern Saudi Arabia. Seven brine samples were taken from Sabkha Jayb Uwayyid in eastern Saudi Arabia. Brine chemistry, saturation state with respect to carbonate and evaporate minerals, and evaporation-driven geochemical reaction paths were investigated to delineate the origin of brines and the evolution of both brine chemistry and sabkha mineralogy. The average total dissolved solids in the sabkha brines is 243 g/l. The order of cation dominance is Na+   >>  Mg2+ >>  Ca2+>K+, while anion dominance is Cl− >> SO4 2− >> HCO3 −. Based on the chemical divide principle and observed ion ratios, it was concluded that sabkha brines have evolved from deep groundwater rather than from direct rainfall, runoff from the surroundings, or inflow of shallow groundwater. Aqueous speciation simulations show that: (1) all seven brines are supersaturated with respect to calcite, dolomite, and magnesite and undersaturated with respect to halite; (2) three brines are undersaturated with respect to both gypsum and anhydrite, while three brines are supersaturated with respect to both minerals; (3) anhydrite is a more stable solid phase than gypsum in four brines. Evaporation factors required to bring the brines to the halite phase boundary ranged from 1.016 to 4.53. All reaction paths to the halite phase boundary follow the neutral path as CO2 is degassed and dolomite precipitates from the brines. On average, a sabkha brine containing 1 kg of H2O precipitates 7.6 g of minerals along the reaction path to the halite phase boundary, of which 52% is anhydrite, 35.3% is gypsum, and 12.7% is dolomite. Bicarbonate is the limiting factor of dolomite precipitation, and sulfate is the limiting factor of gypsum and anhydrite precipitation from sabkha brines.  相似文献   

6.
《Applied Geochemistry》1998,13(5):553-569
The chemical evolution of the Kurnub Group paleowater was studied starting from rainwater in recharge areas of the Sinai and along groundwater flowpaths leading to the natural outlets of this regional aquifer. This was achieved by investigating the chemical composition of groundwater, ionic ratios, degrees of saturation with common mineral species, normative analysis of dissolved salts and by modeling of rock/water interaction and mixing processes occurring along groundwater flow paths. The initial groundwater composition used is from the Nakhel well in Sinai. It evolves from desert rainwater percolating through typical Kurnub Group lithology in Sinai. This rainwater dissolves mainly gypsum, halite and dolomite together with smaller amounts of marine aerosol and K-feldspar. At the same time it precipitates calcite, SiO2, smectite and degasses CO2. Between the area of Nakhel and the northern Negev the chemistry of Kurnub Group waters is influenced by dissolution of halite and lesser amounts of gypsum of surficial origin in recharge areas, small amounts of feldspars and of dolomite cement in sandstones eroded from the Arabo-Nubian igneous massif of Sinai and organic degradation-derived CO2. Concomitantly, there is precipitation of calcite, smectite, SiO2 and probably analcime characteristic of sediments in continental closed basins. North of the Negev, the Kurnub Group fluids are diluted and altered by mixing with Judea Group aquifer groundwaters. On the E there is mixing with residual brines from the water body ancestral to the Dead Sea, prior to discharge into the Arava valley. Rock/water interaction indicated by NETPATH and PHREEQC modeling is in agreement with lithology and facies changes previously observed in the Kurnub Group sequence.  相似文献   

7.
以揭示河北平原深层碱性淡水化学形成机制为主要研究目的, 选择河北平原深层碱性淡水发育的保定、沧州地区为典型研究区, 应用水文地球综合分析方法和地下水地球化学模拟技术, 探讨了深层碱性淡水水化学性质、分布规律及形成的自然环境; 依据质量守恒原理建立深层地下水质量平衡反应模型, 研究了从山前至滨海整个水流路径上所发生的水文地球化学作用及水、岩间的质量交换, 从而揭示了深层地下水化学演化规律的内涵及深层碱性淡水水化学形成机制.主要结论是深碱性淡水是由山前补给区HCO3-Ca·Mg水逐步演化而来, 从山前至中部平原, 在地下水环境由开放转为封闭的过程中, 方解石、白云石溶解和沉淀, 钠长石、石膏、岩盐和菱铁矿的溶解, Ca-Na阳离子交换是控制其形成和演化的主要水文地球化学作用.   相似文献   

8.
A geographical information system (GIS) assisted approach that couples a groundwater flow model and an inverse geochemical model is presented to quantify the phase mole transfers between two points on the flow path within a groundwater system. It is used to investigate the plausible phase transfers in the unconfined aquifer of Mehsana district of Gujarat State, India. X-ray diffraction analysis of soil samples is carried out for mineral characterization. The groundwater flow field is simulated using MODFLOW and flow paths used for inverse geochemical modeling are traced using PMPATH, a particle tracking algorithm. The plausible phase mole transfers in the flow path are quantified using PHREEQC geochemical code. The different scenarios generated by inverse modeling routine are used as input to the geochemical model and simulation runs are taken as forward models. The obtained results are compared to the target solution chemistry by using the square of the Pearson product moment correlation coefficient. Results reveal that the groundwater is undersaturated with anhydrite, carbon dioxide (gas), fluorite, gypsum, halite, jarosite-K, and siderite. It is oversaturated with aragonite, calcite, dolomite, ferrihydrite, goethite, and hematite. Results further reveal that calcite is precipitating, while dolomite, gypsum, carbon dioxide, and fluorite are dissolving together with ion exchange in the flow path.  相似文献   

9.
应用离子比例系数法分析了峰峰矿区东部地下水化学成分特征,结合含水层岩性条件,为水文地球化学模拟中“可能矿物相”的确定提供依据;采用PHREEQC软件对含水层中水-岩作用进行水文地球化学模拟,模拟计算出饱和指数,通过质量平衡模拟计算水-岩作用过程中主要矿物相的转化量。结果表明:方解石和白云石处于饱和状态,在适当的条件下会沉淀,而岩盐、石膏处于未饱和的状态,在适当的条件下将继续溶解。沿地下水流路径,从五矿奥灰水-一矿奥灰水-一矿副井水,地下水系统中白云石、岩盐、石膏溶解,方解石沉淀,且发生了阳离子交换作用。研究矿井水中水-岩相互作用,初步探讨废弃矿井水文地球化学演化机制,对分析矿井水文地球化学演化的影响因素有重要作用。   相似文献   

10.
Presence of fluoride in groundwater is a public health problem in the so-called endemic fluorosis belt of the central Iran, where the groundwater is the major source of drinking water in most urban and rural areas. Therefore, an attempt has been made to determine the hydrogeochemical factors controlling fluoride enrichment in the groundwater resources at this belt. Fluoride concentrations ranged from 0.20 to 1.99 mg/L (1.02 ± 0.47) in groundwater samples. The presence of different F-bearing minerals and also clay minerals in the soils and aquifer materials was confirmed using XRD analysis. To identify probable sources of dissolved F? and investigate groundwater quality, multivariate statistical analyses were carried out. Geochemical modeling indicated that all samples were undersaturated with respect to fluorite, halite, gypsum and anhydrite and mostly oversaturated with respect to calcite and dolomite. Contrary to most high-fluoride regions in the World, the high F? content was dominated by Na–Cl- and Ca–SO4-type groundwater in the study area. Besides, fluoride showed negative relationship with pH and HCO3 ? in groundwater. In order to assess the bioavailability of fluoride in soils, a two-step chemical fractionation method was applied. The results showed that fluoride in soils mostly accompanied with the residual and water-soluble fractions and was poorly associated with soil’s bonding sites. Calculated aqueous migration coefficient demonstrated that fluoride in the studied soils was mobile to easily leachable to the groundwater. Finally, the results demonstrated that combination of water–rock interaction and influence of clay minerals is geochemical mechanism responsible for controlling fluoride enrichment in groundwater.  相似文献   

11.
河套灌区西部浅层地下水咸化机制   总被引：2，自引：0，他引：2       下载免费PDF全文
浅层地下水水位埋深浅、含盐量高,是导致河套灌区土壤次生盐渍化的重要原因.以河套灌区西部地区为研究区,通过对浅层地下水的水化学和氢氧同位素特征分析以及水文地球化学模拟,探讨了灌区浅层地下水的补给来源和主控水-岩作用过程,并定量估算了蒸发作用对浅层地下水含盐量的影响.研究区内浅层地下水为弱碱性咸水,pH为7.23~8.45,总溶解性固体（total dissolved solids,TDS）变化范围为371~7 599 mg/L;随着地下水咸化程度增大,水化学类型由HCO3-Na·Mg·Ca型向Cl-Na型过渡.引黄灌溉和大气降水是浅层地下水的主要补给来源,径流过程中浅层地下水受蒸发作用和植物蒸腾作用影响,地下水化学组分主要来源于蒸发盐溶解和硅酸盐风化水解,并受强烈的蒸发作用和离子交换作用影响.水文地球化学模拟和主成分分析结果显示,蒸发作用和岩盐溶解作用对区内浅层地下水咸化贡献最大,石膏和白云石等矿物的溶解、硅酸盐的水解、Na-Ca离子交换以及局部地形起伏对地下水咸化过程也有较大贡献.   相似文献   

12.
The systematic sampling of the chemical composition of the groundwater from five karst springs (including an overflow spring) and one outflowing borehole have permitted to determine distinctive chemical changes in the waters that reflect the geochemical processes occurring in a carbonate aquifer system from southern Spain. The analysis of the dissolution parameters revealed that geochemical evolution of the karst waters basically depends on the availability of the minerals forming aquifer rocks and the residence time within the aquifers. In the three proposed scenarios in the aquifers, which include the preferential flow routines, the more important geochemical processes taking place during the groundwater flow from the recharge to the discharge zones are: CO2 dissolution and exsolution (outgassing), calcite net dissolution, calcite and dolomite sequential dissolution, gypsum/anhydrite and halite dissolution, de-dolomitization and calcite precipitation. A detailed analysis of the hydrochemical data set, saturation indices of the minerals and partial pressure of CO2 in the waters joined to the application of geochemical modelling methods allowed the elaboration of a hydrogeochemical model of the studied aquifers. The developed approach contributes to a better understanding of the karstification processes and the hydrogeological functioning of carbonate aquifers, the latter being a crucial aspect for the suitable management of the water resources.  相似文献   

13.
在开展曹妃甸地区环境地质调查评价过程中,利用水化学组分及离子组合方法对曹妃甸地区水化学样品进行分析,结合曹妃甸地区水文地质条件,开展了地下水水化学形成作用研究,认为该区浅层地下水以溶滤地层中的岩盐、碳酸盐矿物和硅酸盐矿物为主,方解石、石膏等贫镁矿物的影响较小,同时,强烈的蒸发浓缩作用对浅层水水化学特征具有重要影响。深层...  相似文献   

14.
An approach is presented to investigate the regional evolution of groundwater in the basin of the Amacuzac River in Central Mexico. The approach is based on groundwater flow cross-sectional modeling in combination with major ion chemistry and geochemical modeling, complemented with principal component and cluster analyses. The hydrogeologic units composing the basin, which combine aquifers and aquitards both in granular, fractured and karstic rocks, were represented in sections parallel to the regional groundwater flow. Steady-state cross-section numerical simulations aided in the conceptualization of the groundwater flow system through the basin and permitted estimation of bulk hydraulic conductivity values, recharge rates and residence times. Forty-five water locations (springs, groundwater wells and rivers) were sampled throughout the basin for chemical analysis of major ions. The modeled gravity-driven groundwater flow system satisfactorily reproduced field observations, whereas the main geochemical processes of groundwater in the basin are associated to the order and reactions in which the igneous and sedimentary rocks are encountered along the groundwater flow. Recharge water in the volcanic and volcano-sedimentary aquifers increases the concentration of HCO3 –, Mg2+ and Ca2+ from dissolution of plagioclase and olivine. Deeper groundwater flow encounters carbonate rocks, under closed CO2 conditions, and dissolves calcite and dolomite. When groundwater encounters gypsum lenses in the shallow Balsas Group or the deeper Huitzuco anhydrite, gypsum dissolution produces proportional increased concentration of Ca2+ and SO4 2–; two samples reflected the influence of hydrothermal fluids and probably halite dissolution. These geochemical trends are consistent with the principal component and cluster analyses.  相似文献   

15.
应用水文地球化学模拟(PHREEQC软件)对咸阳城区地下热水进行了水文地球化学演化和路径模拟.模拟路径分别为西、西北两个补给方向.模拟结果表明,,地下水流向发生了一系列的水-岩反应,,线R5→SP2,SP2水化学类型由Na-HCO2-Cl转化为Na-Cl型,而西北线R6→SP2水化学类型由Na-Ca-HCO3 -el转化为Na-Cl型,在水流路径上SiO2(玉髓)、方解石、白云石和高岭石发生了沉淀,而岩盐、石膏、天青石、钠长石、云母和萤石发生了溶解作用.对研究区地下热水地球化学反应路径模拟,描述了研究区地下热水补给到排泄的演化特征,表明水-岩作用模拟对于揭示研究区地下水化学演化环境具有重要的指示意义.  相似文献   

16.
人类活动对鄱阳湖赣江流域水质的影响受到广泛关注,厘清流域内污染水体对人类的健康风险状况有利于更好地保护和利用水资源。本研究于赣江下游采集39个地下水和16个地表水样,在分析其水化学特征和影响因素的基础上,对地下水水化学成分演变进行反向模拟,并对地下水水质以及潜在非致癌风险进行评价。结果表明,研究区地下水呈弱酸性-中性(pH=5.47~7.60),以HCO3-Ca-Mg型水为主,部分为Cl-Ca-Mg型水,硅酸岩风化和矿物溶解-沉淀作用是水化学类型形成的主要控制因素;地表水呈中性-弱碱性(pH=6.94~8.19),主要为HCO3-Cl-Ca-Na型水,其形成与硅酸岩风化、大气降水和人类活动有关。PHREEQC模拟计算结果表明,地下水中大部分矿物饱和指数(SI)为负数,其中岩盐的SI为-7.80~-9.53,指示该矿物溶解剧烈;白云石、石膏和方解石的SI分别为-1.72~-6.39、-1.65~-3.96、-0.51~-3.09,表明三种矿物呈溶解趋势。反向模拟结果显示,赣江干流地下水化学特征演变过程经历了Ca-蒙脱石、岩盐、白云石溶解和方解石沉淀,同时消耗CO2;支流中命名为NCGW-3的路径表现为高岭石、方解石、玉髓和白云石溶解,石膏、Ca-蒙脱石、黑云母和斜长石沉淀,同时产生CO2,可能与人为作用的干扰有关。其余支流地下水反向模拟结果与干流结果相似。熵权水质指数(EWQI)计算结果表明,干流地下水水质优于支流地下水,沿赣江受Mn、N O 3 -影响水质降低;地下水非致癌潜在风险主要为对婴儿存在严重风险,其次是儿童,对成年男性和成年女性风险相对较小,支流水质存在的潜在风险相较于干流更为显著。  相似文献   

17.
In Wadi Tharad the groundwater has been subjected to hydrochemical study to identify the process (s) that led to the formation of relatively highly saline water in shallow alluvial aquifer. The chemical analyses results show that the groundwater salinity was highly variable and randomly distributed along the wadi course. This variation could be attributed to intensive evaporation on effluent prone surface irrigation water that led to precipitation of evaporates (e.g., calcite, dolomite, gypsum and probably halite). The intensive irrigation practice through mineral dissolution recharged the groundwater with a marked increase in the salinity. The local hydrogeological condition is also involved in determining the risk of the groundwater salinity as a consequence of irrigation practice. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

18.
刘海  康博  沈军辉 《现代地质》2019,33(2):440-450
在了解安徽省泗县水文地质条件基础上,分析了区域水文地球化学特征及类型,探讨了其空间分布特征。根据开采条件下的地下水动力场条件,选择了3条模拟路径,采用PHREEQC软件进行了水文地球化学模拟研究,定量分析了地下水的形成机理及演化。结果表明,路径Ⅰ发生了岩盐、石膏以及伊利石的溶解,高岭土、石英、白云石、萤石发生了沉淀;钙蒙脱石、方解石不参与反应,NaX解吸,CaX_2被吸附;路径Ⅱ发生了岩盐、石膏、伊利石、石英等的溶解以及钙蒙脱石、方解石的沉淀,NaX解吸,CaX_2被吸附;路径Ⅲ发生的反应基本与路径Ⅰ相同,不同之处在该路径上的白云石发生了溶解,其原因可能是地下水在径流过程中溶解CO_2,使其继续溶解白云石以及受沉淀滞后的影响。研究结果表明地下水开采条件下,泗县地下水化学组分主要受到了岩盐和石膏等矿物的溶解作用、钙钠离子交换作用以及钙蒙脱石、方解石沉淀作用的控制。  相似文献   

19.
Flows of different hierarchy, which travel through limestone, schist, sandstone and ultra-basic rocks, with ages from the Paleocene to the Jurassic, at Sierra del Rosario, Pinar del Río, Cuba, were characterized. The waters were sampled from 1984 until 2004 and the data were statistically processed by means of chemical equilibrium and physico-chemical models, under a flow system view of interpretation. Results demonstrate that the physico-chemical properties of the water are controlled by water–rock interaction resulting from residence time since rainwater infiltrate and the path it follows to the discharge zone and the type of aquifer material the different groundwater flows are in contact with. Geochemical indices allow the definition of the different types of flow (local, intermediate, regional) to be characterized, permitting a further definition of the different flow systems and rock type involved, as well as its use for water supply and medical use. The main geochemical processes which control the chemical composition acquisitions mode are: congruent dissolution of calcite, dolomite, and halite; incongruent dissolution of plagioclase and microcline minerals; pyrite oxidation, sulphate reduction, and silica dissolution at the surface or silica precipitation at deep saturation and circulation zones.  相似文献   

20.
Groundwater is a critical resource in Deoria district, as it is the main source of drinking water and irrigation. The aquifer has deteriorated to a high degree, during the last two to three decades, in quality and quantity due to high population growth and environmental pollution. More than 90% of the population get their drinking water from subsurface waters. Fifteen wells were sampled in June 2006 to probe the hydrogeochemical components that influence the water quality. The results show that groundwater have EC, TDS, Na+, Mg2+, HCO3− and TH higher than the WHO, 1997 maximum desirable limits. A hydrogeochemical numerical model for carbonate minerals was constructed using the PHREEQC package. The regression analysis shows that there are three groups of elements which are significantly and positively correlated. The main hydrochemical facies of the aquifer (Ca + Mg–HCO3) represents 33.33% of the total wells. The geochemical modeling demonstrated that the reactions responsible for the hydrochemical evolution in the area fall into three categories: (1) dissolution of salts, (2) precipitation of dolomite, (3) ion exchange. Solubility of dolomite, calcite, aragonite and gypsum were assessed in terms of the saturation index. The thermodynamic prerequisites for dolomite supersaturation reactions are satisfied by subsurface waters, since they are supersaturated with respect to dolomite, undersaturated (or in equilibrium) with respect to calcite, and undersaturated with respect to gypsum. The Ca2+ versus SO42− and Mg2+ versus SO42− trends are also compatible with homologous trends resulting from dolomite supersaturation.  相似文献   

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