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31.
在对吉兰泰盐湖南部地下水化学组分特征分析的基础上,利用PHREEQC软件对水文地球化学演化规律进行模拟研究。结果表明,从贺兰山西侧山前到吉兰泰盐湖,水化学类型由HCO-3型过渡到Cl-—SO2-4型、最后变为Cl-型;Ca2+、Mg2+与SO2-4相关分析表明发生石膏溶解出的Ca2+置换了MgCO3中Mg2+,从而产生了CaCO3沉淀的水岩反应,而白云石、石膏、岩盐、CO2(g)的溶解是常量离子增加的物质来源,同时伴有强烈的蒸发浓缩作用及阳离子交换作用。特别是深层地下水具有较高的mNa/Cl值与较低的mCa/Na值,表明发生强烈的阳离子交换作用,这对认识吉兰泰盐湖地区及干旱区沙漠地区水体发生的水岩相互作用与演化机制具有借鉴作用。 相似文献
32.
The Agua Negra drainage system (30 12′S, 69 50′ W), in the Argentine Andes holds several ice‐ and rock‐glaciers, which are distributed from 4200 up to 6300 m a.s.l. The geochemical study of meltwaters reveals that ice‐glaciers deliver a HCO3?? Ca2+ solution and rock‐glaciers a SO42?? HCO3?? Ca2+ solution. The site is presumably strongly influenced by sublimation and dry deposition. The main processes supplying solutes to meltwater are sulphide oxidation (i.e. abundant hydrothermal manifestations), and hydrolysis and dissolution of carbonates and silicates. Marine aerosols are the main source of NaCl. The fine‐grained products of glacial comminution play a significant role in the control of dissolved minor and trace elements: transition metals (e.g. Mn, Zr, Cu, and Co) appear to be selectively removed from solution, whereas some LIL (large ion lithophile) elements, such as Sr, Cs, and major cations, are more concentrated in the lowermost reach. Daily concentration variation of dissolved rare earth elements (REE) tends to increase with discharge. Through PHREEQC inverse modelling, it is shown that gypsum dissolution (i.e. sulphide oxidation) is the most important geochemical mechanism delivering solutes to the Agua Negra drainage system, particularly in rock‐glaciers. At the lowermost reach, the chemical signature appears to change depending on the relative significance of different meltwater sources: silicate weathering seems to be more important when meltwater has a longer residence time, and calcite and gypsum dissolution is more conspicuous in recently melted waters. A comparison with a non‐glacierized semiarid drainage of comparable size shows that the glacierized basin has a higher specific denudation, but it is mostly accounted for by relatively soluble phases (i.e. gypsum and calcite). Meltwater chemistry in glacierized arid areas appears strongly influenced by sublimation/evaporation, in contrast with its humid counterparts. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
33.
Hydrogeological and hydrochemical characterization of the Voltaian Basin: the Afram Plains area,Ghana 总被引：1，自引：0，他引：1
In the Afram Plains area, groundwater is the main source of water supply for most uses. The area is underlain by aquifers
of the southern Voltaian sedimentary basin, which are predominantly sandstones, mudstones, conglomerates and shale. Ordinary
least squares regression analysis using 41 well-test data from aquifers in the Afram Plains portion of the Voltaian system
reveals that transmissivity, T, exists in a non-linear relationship with specific capacity, Sc. The analysis reveals that T = 0.769Sc1.075 with R
2 = 0.83 for aquifers in the area. The mudstone/conglomerate aquifer in the area appears to be the most variable in terms of
both specific capacity and transmissivity with transmissivity ranging from 0.18 to 197.7 m2/day and 0.5 and 148.5 m3/day/m, respectively. Horizontal fractures and joints resulting from secondary fracturing appear to be the main determinants
of both transmissivity and specific capacity in the area. PHREEQC modeling and mineral stability diagrams indicate that groundwater
quality in the Afram Plains area is controlled by the incongruent weathering of silicate minerals in the aquifers. These processes
concentrate calcium, sodium, magnesium, potassium, bicarbonate ion and quartz, leading to calcite, dolomite and aragonite
supersaturation at most locations. Hierarchical cluster analysis performed on the raw chemical data reveals two main water
types or facies: the calcium–sodium–chloride–bicarbonate facies, and the magnesium–potassium–sulfate–nitrate facies for the
southern and northern sections of the Afram Plains area, respectively. 相似文献
34.
Geochemical evidence of seawater intrusion into a coastal geothermal field of central Greece: example of the Thermopylae system 总被引：1，自引：0，他引：1
A. Duriez C. Marlin E. Dotsika M. Massault A. Noret J. L. Morel 《Environmental Geology》2008,54(3):551-564
Thermal water of Thermopylae and from other geothermal fields located in the southern part of the Sperchios basin (central
Greece) are characterized by high salinity (total dissolved salts, or TDS, range from 1.2 to 30.3 g L−1) associated with a degassing of CO2. To determine the mineralization processes, geochemical and isotopic investigations (major elements, 18O, 2H and 13C) have been carried out upon 17 thermal waters from springs and boreholes. This study emphasizes that all the thermal waters
result from the mixing of a seawater end-member, several fresh water components depending on the field location, and a mantle-derived
CO2 rising upward through an E–W fault system. The seawater identified in the thermal mixture is likely to be evolved Aegean
seawater (ASW). Once intruded into the basin sediments, the trapped seawater has its chemical content modified by both water–rock
interactions and massive dissolution of the deep CO2 (pCO2 of 100.5 atm). The modelling performed with PHREEQC indicates that the anomalous major ion ratios measured in the so-called evolved
ASW are explained by the dissolution of calcite and dolomitization process associated to precipitation of gypsum within the
thermal aquifer. 相似文献
35.
奇村地热田水化学特征及其混合作用模拟 总被引：1，自引：1，他引：1
本文通过对奇村地热田地下水水化学资料及其水化学空间分布特征的分析,解释了本区地下水水化学成分的形成和演化机理;同时运用PHREEQC软件模拟,得出目前开采冷、热水的混合比范围为1.0∶1~3.2∶1,从而为合理开发利用地下热水提供了依据。 相似文献
36.
银北地区土壤盐渍化形成机理与模拟研究 总被引：1，自引：1，他引：1
银北地区位于干旱、半干旱气候带,降水稀少,蒸发强烈,导致本地区土壤盐渍化严重。近年来,由于黄河来水量的逐年减少,引黄灌溉不能满足农业灌溉需求,逐渐开始开采利用地下水。由于银北地区浅层地下水矿化度较高,利用地下水灌溉可能引起次生土壤盐渍化。本文运用PHREEQC模型软件模拟灌溉水与土壤之间的相互作用过程,探讨了土壤盐渍化的形成机理。通过模拟分析得到以下结论:(1)地表水和地下水联合运用是解决银北灌区土壤盐渍化的关键,不同地区采取不同的混合比例,可以实现水资源的高效利用。(2)银北地区灌溉淋洗期间存在蒸发浓缩叠代在2~4次,说明存在轻微蒸发。(3)INVERSE模拟结果说明,银北地区灌溉淋洗期间存在轻微蒸发,水相和固相的相互作用,石膏、白云岩和盐岩溶解,Na 、Ca2 和Mg2 吸附交换,渠水下渗转化为地下水;非灌水期地下水通过毛细管作用强烈蒸发,水相和固相的相互作用,石膏、白云岩和盐岩沉淀,Na 、Ca2 和Mg2 解吸附,使有害盐分氯化物、硫酸盐存留在土壤层中,形成土壤盐渍化。 相似文献
37.
水工建筑物排水孔洞中常常析出大量各色固体物质,对水工建筑物的安全稳定运行产生不可忽视的影响。某大型水利工程排水孔洞中析出物是典型的地下水环境变化下的水文地球化学现象,应用PHREEQC定量模拟析出量结果表明:单位长度析出量介于0.0303～0.9124kg/a,大坝析出物问题并不严重;一、二、三、五、七号单元的单位长度析出量小于0.66kg/a;四号、六号单元的单位长度析出量分别为0.8656kg/a和0.9124kg/a,属于相对危险部位,应该重点监测。应用PHREEQC定量模拟水-岩相互作用,揭示析出物的水文地球化学变化过程,可以为大坝安全监测提供科学依据。 相似文献
38.
Hydrogeochemical zonation for groundwater management in the area with diversified geological and land-use setup 总被引：1，自引：0，他引：1
Manish Kumar Roger Herbert Jr. AL. Ramanathan M. Someshwar Rao Kangjoo Kim Jyoti Prakash Deka Bhishm Kumar 《Chemie der Erde / Geochemistry》2013
Despite its limited aerial extent, the National Capital Territory (NCT) Delhi, India, has diversified geological and topographical setup. A geochemical assessment of prevailing conditions of aquifer underlying the NCT was attempted and further classified into different hydrogeochemical zones on the basis of statistical and analyses and its correlation with land use, geological and climatic setting. Mineral phase study and isotopic analyses were used for the verification of performed clustering. Saturation indices (SI) calculated using the geochemical modelling code PHREEQC were used to distinguish the characteristics of four zones, as saturation states of the water does not change abruptly. Four different hydrogeochemical zones were statistically identified in the area: (1) intermediate (land-use-change-impacted) recharge zone, (2) discharge (agriculture-impacted) zone, (3) recharge (ridge) zone, and (4) recharge floodplain (untreated-discharge-impacted) zone. The distinctiveness of hydro-geochemical zones was further verified using stable isotopic (2H and 18O) signature of these waters. GIS-based flow regime in association with long-term geochemical evidences implied that these zones are being affected by different problems; thus, it necessitates separate environmental measures for their management and conservation. The study suggested that in a diversified urban setup where the complex interactions between anthropogenic activities and normal geochemical processes are functioning, hydrogeochmical zoning based on the integration of various techniques could be the first step towards sketching out the groundwater management plan. 相似文献
39.
ABSTRACTA study of surface water chemistry evolution was conducted by multivariate statistical analysis and inverse geochemical modelling using the PHREEQC computer program. Using hierarchical cluster analysis the 14 sampling sites were classified into three groups (recharge, transition and discharge areas). Water chemistry changed along a flow path so that waters with Ca–HCO3 and Mg–Cl composition changed to Mg–Cl–HCO3 waters. The order of abundance of the major cations was Mg > Ca > Na > K. Their average concentrations were 21, 19, 3.6 and 2.5 mg L-1, respectively. Inverse geochemical modelling along flow paths indicated that the dissolution of sylvite and kaolinite, and precipitation of feldspars and andalusite, happened with Na entering the solution and Ca, Mg and K leaving the solution.
Editor D. Koutsoyiannis; Associate editor not assigned 相似文献
40.
《Chemie der Erde / Geochemistry》2021,81(2):125742
Over exploitation for agricultural activities and consumption has depleted the groundwater resources of drought-prone northeast Mexico. Major ion concentrations along with δ18OH2O, δ2HH2O and d-excess values of shallow groundwater from the Cieneguilla Basin (near Tula) located at a distance of ∼200 km from coast of the Gulf of Mexico helped to contribute new data about drought vulnerability in this region through identification of the moisture source and groundwater recharge zone. Different degrees of rock-water interaction through gypsum, anhydrite and halite dissolutions and minor silicate weathering controlled the hydrochemistry. Stable isotopes yielded a least square regression and slope similar to the local as well as global meteoric water lines, indicating minimal effect of evaporation during the recharge as well as in the subsoil. Isotopic fractionations along with a digital elevation model demarcated the recharge zones at north and east of the basin, with altitudinal difference of ≥1000 m, and indicated that the recharge occurred through warm season moisture sourced from the Gulf of Mexico. Less frequent landfalling of tropical storms caused by warmer sea surface temperature, however, has reduced this rainfall over the last few decades. If the trend of global warming continues unabated, the depleted groundwater resources would trigger reduction in agricultural activities in this drought-prone region and lead to enhanced socio-economic challenges. 相似文献