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1.
宁南西吉存在范围较大的高氟地下水区,属于高氟水重灾区.以宁南含水层沉积物为研究对象开展室内实验,探讨了pH、Ca2+、Na+、HCO3-和Ca2+/OH-协同作用对沉积物中氟释放的影响及定量关系.结果表明,相对于HCO3-,pH值对F-释放的促进作用更高,相对增量为10％～50％.低Ca2+/ Na+比提高了沉积物所释放F-的活度,有利于地下水中F-的聚集.不同岩性对pH值的缓冲能力不同,从而决定F-的释放.整体而言,粉质粘土、泥岩和粘土F-释放的浓度相对其他岩性要高.泥岩和粉质粘土的F-释放受pH影响较大.沉积物中Al、Fe、Mn、Si组分含量、总F-浓度与不同条件下淋滤出的F-浓度也具备较好的相关性.沉积物的F-含量对地下水中F-聚集有较大的影响. 相似文献
2.
《地质科技情报》2015,(5)
水土界面氟的迁移对高氟地下水的形成具有重要影响。以大同盆地典型氟中毒区为例,分析了不同岩性沉积物中的氟质量分数和形态分布特征,并通过室内静态实验,探究了水溶液的pH值、Ca2+、HCO-3以及H2PO-4质量浓度对水土界面氟迁移的影响。研究结果表明,沉积物中不同形态氟按含量由高到低的顺序依次为:残余态氟铁锰氧化态氟水溶态氟有机束缚态氟离子交换态氟;各形态氟在不同岩性沉积物中含量大小均表现为:黏土粉质黏土粉砂;在沉积物中,黏土矿物和方解石是主要的固氟矿物成分。溶液的pH值、Ca2+、HCO-3以及H2PO-4质量浓度与氟在沉积物表面的吸附-解吸和沉淀-溶解平衡密切相关,沉积物对氟的吸附量随溶液pH值和HCO-3质量浓度增大而降低,随Ca2+和H2PO-4质量浓度增大而增大。 相似文献
3.
地下水中CO2成因分析 总被引：6，自引：2，他引：4
通过对前人成果的总结认为,不同地区由于水文地质条件不同,其地下水中CO2 成因也大不相同。地下水的CO2 的成因主要有来源于大气溶解;土壤及水中有机物分解和生物呼吸;深部热源造成碳酸盐岩或矿物变质;直接由岩浆分泌;除碳酸外其它酸对碳酸盐矿物的溶解; 热水中暂时硬度去除等类型。至于具体到某一地区其地下水中CO2 主要成因为何种,以及各种成因CO2 在地下水中所占比例是多少,应结合具体情况并综合各种相关因素来分析确定。 相似文献
4.
大庆齐家水源地抽取地下水过程中，地下水中CO2和H2S气体大量逸出，造成就地实测的Eh和pH等值不能代表含水层中地下水的真实情况。本文提出用化学热力学模拟恢复水文地球化学环境的方法，在分析齐家水源地实际情况的基础上，界定了齐家水源地的水文地球化学环境指标：pH值、Eh值、游离CO2和H2S，pH值为6．56以下；Eh值为—121-—145mV之间；游离CO2为300mg/L以上；H2S(aq)大于64μg/L；HS^-大于17μg/L。指出大庆齐家水源地为偏酸性、弱还原、高游离CO2，且含H2S的水文地球化学环境；为地下除铁提供了水文地球化学环境依据。 相似文献
5.
由于盖层中可能存在未知断层和裂隙或被废弃井穿透,储存于深部地层的CO2会发生向上运移泄漏影响浅层地下水水质,在天然流场的作用下,受影响含水层在泄漏停止后,可能表现出一定的自我修复能力。以美国某野外试验场地为例,以TOUGHREACT软件为平台,模拟分析当CO2泄漏停止后含水层的自我修复能力。结果表明：CO2泄露进入含水层会降低地下水中的pH值,从而引起地下水中碳酸盐矿物（本次研究中为方解石矿物）的溶解发生;当泄漏停止后,在天然流场的作用下,地下水中pH值逐渐回升,说明天然条件下的含水层对pH值具有一定的自我修复能力,但在修复过程中,由于沿途方解石矿物的溶解,使得地下水中Ca的浓度值逐渐升高,研究区天然流场对地下水中的Ca修复效果不佳。 相似文献
6.
温度对水中碳酸平衡的影响浅析 总被引：3，自引：0，他引：3
本文通过理论分析和计算探讨了0～100℃范围内不同温度下的碳酸平衡问题,分析了H2CO3*、HCO3-和CO32-三种碳酸在不同温度和pH条件下的水中所占比例及分布规律。认为0～100℃范围内pH0在8.60～8.22之间变化,变化范围较小;三种碳酸在不同温度下随pH变化过程中所占比例存在差异,但差异也不大;在0～100℃范围内不管温度高低,均表现出酸性水中H2CO3*占优势,碱性水中CO32-占优势,偏酸、偏碱及中性水中HCO3-占优势;在较低pH下由于水中CO32-含量很少,因此用常规方法一般是难以检测到的。 相似文献
7.
深圳市东湖矿泉水形成机理探讨 总被引：5，自引：0，他引：5
深圳市东湖矿泉水是自然界十分稀少的锶—锌—偏硅酸碳酸复合型矿泉水，通过对矿泉水赋存地的地质与水文地质条件的分析，并结合其水文地球化学特征，认为东湖矿泉水形成的主要控制性因素是构造作用和变质作用；在特定的水文地质条件下，深部碳酸盐类岩石受热硅化变质而产生大量CO2气体，使得各种化学元素在含有大量CO2的地下水的溶滤作用下不断迁移和富集而形成该区地下水中良好的元素组合。在其特征成分中，偏硅酸来自裂隙渗透水的溶滤和岩浆期后热液水的作用，微量元素锶主要来源于钾长石、钙长石，锌则主要来自岩浆活动以及岩脉中的黑云母、角闪石、辉石等铁镁硅酸盐矿物；并认为目前矿泉水含水层仍处于良好的地质环境保护下。 相似文献
8.
成岩作用中的地下水碳酸体系与方解石溶解度 总被引：4，自引：1，他引：4
方解石在沉积岩成岩环境中的溶解度与地下水化学特征、温度等有着极为密切的关系。地下水碳酸体系中各碳酸组分的比例是溶液pH值的函数,可溶性CO2、HCO3-和CO32-分别在pH≤pK1的酸性介质、pK1≤pH≤pK2的弱酸至中性介质和pH≥pK2的碱性介质中具有绝对数量。而地下水体系中碳酸总量及各组分的变化受到pH值、气相CO2分压PCO2及固相方解石的溶解-沉淀效应的控制。通过限定溶液中离子的电价平衡和质量守恒约束条件可以确定各种温压环境中的地下水组成及方解石的溶解度特征。溶液pH值和温度是方解石溶解度的最直接的控制因素,且方解石的溶解随pH值不同分别在强酸、弱酸和碱性介质中表现出不同的反应方式。基于质量守恒条件,溶液中初始[ΣCO2]-[Ca2+]值对中性至碱性介质中的方解石溶解度带来很大的影响,当[ΣCO2]0<[ca2+]0有利于方解石的溶解,当[σco2]0>[Ca2+]0时有利于方解石的沉淀。如果CO2—H2O—CaCO3体系同时受到电价平衡和质量守恒条件的约束,则方解石只在酸性介质中溶解,碱性介质中沉淀。新疆塔里木盆地库车坳陷克拉2气田及相关储层中方解石分布特征表明,该区碎屑岩储层中方解石的大量沉淀发生于重碳酸钠型地下水环境中,而孔隙度极好、次生孔隙发育的储集段则出现于氯化型的地下水环境,从而验证了成岩作用中地下水类型对方解石溶解—沉淀的控制机制。 相似文献
9.
通过珠江三角洲地区两千余组地下水样的pH值现场测试,发现水体酸化是该区地下水环境最为突出的问题之一。偏酸性地下水的分布范围占全区76.3%。该区地下水pH值的分布具有明显的区域性特征。丘陵台地区以偏酸性地下水为主,pH值集中在5.6～6.4;三角洲平原区地下水普遍呈中性,pH值主要介于6.4～7.2。丰、枯水期地下水pH值变幅不大,受酸雨影响,丰水期略有降低。该地区影响地下水pH值的主要因素为酸雨、包气带介质、河流及海水潮汐。丘陵区酸雨入渗强度大、包气带的缓冲能力低,对地下水pH值偏低起了主要作用;平原区粘土层厚,酸雨入渗强度减弱,而河流与地下水交换频繁,加上咸潮与海水入侵的影响,共同导致了地下水pH值升高。 相似文献
10.
大同盆地砷中毒病区沉积物中砷的吸附行为和影响因素分析 总被引：3，自引：0，他引：3
沉积物对砷的吸附-解吸作用是控制砷在地下水中的迁移和转化的决定性因素。对砷中毒重病区大同盆地山胡县沉积物中砷的吸附行为和影响因素研究结果表明,沉积物对砷的吸附符合Freundlich吸附等温模式,吸附量主要与沉积物颗粒大小、黏土矿物质量分数和类型、铁铝氧化物质量分数以及沉积物中As的质量分数有关,有机质质量分数对砷的吸附量影响需进一步深入研究。铝硅酸盐、铁铝氧化物质量分数较高且颗粒较细的黏土和亚黏土类沉积物对砷的吸附性较强;而铝硅酸盐、铁铝氧化物质量分数较低且颗粒较粗的细砂和粉砂类沉积物对砷的吸附性较差,其所处的含水层也是形成高砷地下水的主要含水层。pH值为5．5～8．0时,砷的吸附量最大。大同盆地高砷地下水pH条件非常不利于沉积物中砷的吸附,易形成高砷地下水。该区地下水10℃左右的温度条件非常有利于沉积物对砷的吸附,但由于影响因素较多,且地下水的温度在不同季节会发生一定的变化,其产生的影响还有待进一步研究。 相似文献
11.
Zhou Xun Zhang Hua Zhao Liang Shen Ye Yan Xia Li Rui Zhang Li 《Environmental Geology》2007,53(2):317-323
Groundwater of low total dissolved solids (TDS) of 10 mg/L and low pH ranging commonly from 4.0 to 7.0 occurs in the unconsolidated
unconfined and confined aquifers in the coastal plain near Beihai, Guangxi, China. Minerals in the unconsolidated sediment
of Quaternary are predominated by quartz (more than 50%) with small amount of clay minerals, such as kaolinite, illite and
chlorite. SiO2 accounts for most (more than 70%) of the chemical compositions of the sediments. The sediments contain low concentrations
of soluble constituents (below 300 μg/g) and are predominated by SO4. Abundant recharge from low-TDS precipitation and a long time’s dissolution of the unconsolidated sediments containing small
amount of soluble compositions lead to low TDS of the groundwater in the area. 相似文献
12.
Optimal schemes of groundwater exploitation for prevention of seawater intrusion in the Leizhou Peninsula in southern China 总被引：1，自引：0，他引：1
The Lei-Qiong Depression Zone, near the Leizhou Peninsula in southern China, consists of unconsolidated sediments of 500-3,000 m thickness. Groundwater occurs in a multi-aquifer system in the Leizhou Peninsula. The aquifers receive recharge from precipitation, canal and reservoir infiltration, and discharge mainly through subterranean drainage into the sea. Artificial pumping for drinking and agricultural purposes is another way of groundwater discharge. Groundwater development along the coast faces the threat of seawater intrusion. A quasi-three-dimensional finite element model, containing 457 nodes and 833 elements, has been used to simulate the spatial and temporal distribution of groundwater levels in the three-aquifer system. Verification of various aquifer parameters and boundary conditions was performed with the simulation model. Linear programming models have been developed for groundwater exploitation within the two confined aquifers. The objective function of the models is to maximize the total groundwater pumpage from the confined aquifers. Control of seawater intrusion is examined by restricting the water levels at points along the coast and the withdrawal rates in coastal management cells. A response matrix approach was used in the optimization models. The response matrix was obtained from the simulation model by forecasting drawdown produced by pumping at a unit impulse discharge. Groundwater development in the Leizhou Peninsula can be primarily optimized by allocating the pumping rates of the management cells. 相似文献
13.
14.
针对采煤对松散含水层地下水扰动程度评价方法适用性不足等问题,以神东补连塔井田为研究背景,通过分析采煤对地下水动力场的影响规律,得出矿井水（矿井排水与采空区储水）的形成是导致大气降水、地表水与地下水转化关系和转化量发生改变的主要原因;并从松散含水层生态水位变化、含水层损伤以及水量损失的角度,提出了采煤对地下水扰动程度的3个评价指标,结果显示,截至2012年补连塔井田松散含水层地下水生态水位扰动指标基本均大于1,采扰比达92%,说明采煤对生态水位影响较大;由于采动裂隙直接发育至松散含水层内部,导致井田范围内8%面积的含水层完全损伤而失去地下水调蓄能力;而在重复利用矿井水并开发地下水库储水功能的条件下,补连塔矿地下水量损失减少至8.5%,说明矿井水的充分利用对减少地下水资源损失意义重大。 相似文献
15.
Assessing aquifer vulnerability to pollutants by electrical resistivity tomography (ERT) at a nitrate vulnerable zone in NE Spain 总被引：1，自引：0，他引：1
There is an increasing demand for groundwater vulnerability maps which illustrate the exposure of aquifers against pollution.
These maps show areas of greatest potential for groundwater contamination on the basis of local subsurface conditions. Parameters
affecting vulnerability are mainly permeability and thickness of each protective layer. For unconsolidated sediments, the
permeability is strongly related to the clay content, which can be deduced from indirect resistivity methods, like electrical-imaging.
Such geophysical methods can be of great help in groundwater vulnerability studies because they disturb neither the structure
nor the dynamics of the soil. Sensibility analysis was performed of the electrical resistivity tomography method for accurately
mapping soil media. Managers and public administrators may effectively use this method for assessing the potential risk of
groundwater contamination. In the studied zone, electrical resistivity exhibits a wide range of variability that can be easily
correlated to soil parameters, such as clay content and hydraulic conductivity. A numerical index of protection has been assessed
from the geophysical information derived from 2D electrical resistivity tomography. This work represents a preliminary approach
on the natural vulnerability evaluation of shallow aquifers at the Empordà basin (NE Spain) that is highly affected by diffuse
pollution by nitrates. 相似文献
16.
Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment,Germany 总被引：1，自引：0，他引：1
L. P. Gumm V. F. Bense P. F. Dennis K. M. Hiscock N. Cremer S. Simon 《Hydrogeology Journal》2016,24(1):99-108
Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low δ2H and δ18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7?×?10?4 cm3 (STP) g–1?±?2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of helium provides a groundwater residence time of ～107 years. Although fluid exchange between the deep basal aquifer system and the upper aquifer layers is generally impeded by confining clay layers and lignite, this study’s geochemical data suggest, for the first time, that deep circulating fluids penetrate shallow aquifers in the locality of fault zones, implying that sub-vertical fluid flow occurs along faults in the LRE. However, large hydraulic-head gradients observed across many faults suggest that they act as barriers to lateral groundwater flow. Therefore, the geochemical data reported here also substantiate a conduit-barrier model of fault-zone hydrogeology in unconsolidated sedimentary deposits, as well as corroborating the concept that faults in unconsolidated aquifer systems can act as loci for hydraulic connectivity between deep and shallow aquifers. The implications of fluid flow along faults in sedimentary basins worldwide are far reaching and of particular concern for carbon capture and storage (CCS) programmes, impacts of deep shale gas recovery for shallow groundwater aquifers, and nuclear waste storage sites where fault zones could act as potential leakage pathways for hazardous fluids. 相似文献
17.
An assessment of the origin and variation of groundwater salinity in southeastern Ghana 总被引：1，自引：1，他引：0
Groundwater from the major aquifers in southeastern part of Ghana was sampled to determine the main controls on groundwater
salinity in the area. This paper uses multivariate statistical methods, conventional graphical methods and stable isotope
data to determine spatial relationships among groundwaters from the different hydrogeologic units in the area on the basis
of salinity. Q-mode hierarchical cluster analysis (HCA) was used to spatially classify the samples, whilst R-mode factor analysis
was used to reduce the dataset into two major principal components representing the sources of variation in the hydrochemistry.
Analysis of the major chemical parameters suggests that the principal component responsible for salinity increment in the
area is the weathering of minerals in the aquifers. This factor is especially more significant in the upland areas away from
the coast. The second factor responsible for salinity in the area is the combined effects of seawater intrusion, and anthropogenic
activities. This study finds that four major spatial groundwater groups exist in the area: low salinity, acidic groundwaters
which are mainly derived from the Birimian and Togo Series aquifers; low salinity, moderate to neutral pH groundwaters which
are mainly from the Voltaian, Buem and Cape Coast granitoids; very high salinity waters which are not suitable for most domestic
and irrigation purposes and are mainly from the Keta aquifers; and intermediate salinity groundwaters comprising groundwater
from the Keta basin aquifers with minor contributions from the other major terrains. The major water type identified in this
study is the Ca–Mg–HCO3 type, which degrades into predominantly Na–Cl–SO4 more saline groundwaters toward the coast. Stable isotope data analyses suggest that groundwater in the Voltaian aquifers
is largely of recent meteoric origin. The Birimian and Togo aquifers receive a component of recharge from the tributaries
of the Densu and Volta Rivers, after the waters have undergone evaporative enrichment of the heavier isotopes. In the Keta
basin, recharge is mainly from precipitation but an observed enrichment of 2H and 18O isotopes is probably due to seawater and evaporative effects since the water table there is very shallow. An analysis of
the irrigation quality of groundwater from the six aquifers in the study area using sodium adsorption ratio and electrical
conductivity suggests that most of the aquifers supply groundwater of acceptable quality for irrigation. The only exception
is the Keta Basin area, where extremely high salinities and SAR values render groundwater from this basin unsuitable for irrigation
purposes. 相似文献
18.
Sattam Almadani Hussain Alfaifi Abdullah Al-Amri Mohamed Fnais Elkhedr Ibrahim Kamal Abdelrahman Mohammed Shehata Faisal Zaidi 《Arabian Journal of Geosciences》2017,10(6):139
This study was carried out in the Alwadeen area of Khamis Mushayt district of southwestern Saudi Arabia to evaluate the hydrochemical characteristics of the shallow hard rock aquifers. These hard rock aquifers mostly comprise granites and contain significant quantities of groundwater that complement the available groundwater from the unconsolidated alluvial sediments in the nearby wadis. The field investigation indicates two main fracture sets which intersect each other and are oriented in the west-northwest and east-west directions. The granitic rocks in the area are intruded by coarse-grained and quartz-rich monzogranite and pegmatite veins. Hydrogeologically, the fracture systems are important since they facilitate the groundwater storage and assume the transmissive function during times of groundwater abstraction. Given the fact that groundwater in the fractured rock aquifers generally occurs at shallow depths, it may be exposed to contamination from surface and/or near-surface sources, and it is therefore important to evaluate its quality. To this end, a hydrochemical analysis was carried out on six groundwater samples collected from the area. The hydrochemistry revealed that the groundwater is fairly fresh, and facies analysis reveals mixed Na-Cl and Ca-Mg-Cl-SO4 types. Overall, the results reveal that the groundwater is saturated with calcite and dolomite, but unsaturated with gypsum and halite. The degree of salinity increases in the direction of the groundwater flow due to increased rock-water interaction. 相似文献
19.
矿区深部含水层水-岩作用的同位素与水化学示踪分析 总被引：3，自引：0，他引：3
为了有效揭示华北隐伏型煤矿区煤炭开采进程中深部含水层水-岩作用机制,本文以淮北煤田宿县-临涣矿区为研究示范,收集与采集1985～2011年期间矿区松散层第四含水层、煤系砂岩裂隙含水层、石炭系太原组岩溶含水层与奥陶系岩溶含水层深部地下水样166个,分析与测试87Sr/86Sr、34S、13C同位素以及Na++K+、Ca2+、Mg2+、HCO-3、Cl-、SO2-4、CO2-3等常规组分,并开展基于同位素与水化学的水-岩作用示踪与分析。研究成果表明:在矿区主要充水含水层中,煤系砂岩裂隙含水层脱硫酸与阳离子交替吸附作用最为显著,而松散层第四含水层、石炭系太原组岩溶含水层与奥陶系岩溶含水层黄铁矿氧化或地下水硬化最为显著;受煤炭开采影响,煤系砂岩裂隙含水层、奥陶系岩溶含水层主要水-岩作用逐渐减弱,松散层第四含水层、石炭系太原组岩溶含水层主要水-岩作用或增强、或减弱,增强或减弱的程度取决于井田基岩面标高、主要断层的展布形态与隔水性能以及煤层开采扰动范围等。 相似文献
20.
开采孔隙承压含水系统，引起含水层水头下降。通常认为相邻含水层一经出现水头差，便会有通过粘性土层的越流渗透。但在粘性土两侧含水层出现水头差初期，粘性土内部水头降低缓慢，并伴随有释水压密过程。本文采用多用途饱水粘性土固结和渗透试验装置，对不同岩性的粘性土原状样进行了释水、吸水与越流发展过程之间关系的试验。试验表明，含水层水位升、降变化，首先引起相邻粘性土吸水回弹或释水压密，而后出现粘性土吸水或与释水越流并存阶段。越流的出现。明显滞后于含水层水头变化，当吸水或释水过程结束后，越流渗透达到稳定。越流滞后时间与土的固结程度有关，笔者采用一维固结理论提出了计算越流滞后时间的方法。 相似文献