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1.
Groundwater is the most important source of water supply in the Yeniceoba Plain in Central Anatolia,Turkey.An understanding of the geochemical evolution of groundwater is important for the sustainable development of water resources in this region.A hydrogeochemical investigation was conducted in the Plio-Quaternary aquifer system using stable isotopes(δ~(18)O andδD),tritium(~3H),major and minor elements(Ca,Na,K,Mg,Cl,SO_4,NO_3,HCO_3 and Br)in order to identify groundwater chemistry patterns and the processes affecting groundwater mineralization in this system.The chemical data reveal that the chemical composition of groundwater in this aquifer system is mainly controlled by rock/water interactions including dissolution of evaporitic minerals,weathering of silicates,precipitation/dissolution of carbonates,ion exchange,and evaporation.Based on the values of Cl/Br ratio(300 mg/l)in the Plio-Quaternary groundwater,dissolution of evaporitic minerals in aquifer contributes significantly to the high mineralization.The stable isotope analyses indicate that the groundwater in the system was influenced by evaporation of rainfall during infiltration.Low tritium values(generally1 tritium units)of groundwater reflect a minor contribution of recent recharge and groundwater residence times of more than three or four decades. 相似文献
2.
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
3.
The hydrogeochemical characterization of Morsott-El Aouinet aquifer, Northeastern Algeria 总被引：1，自引：0，他引：1
A study of the hydrogeochemical processes in the Morsott-El Aouinet aquifer was carried out with the objective of identifying
the geochemical processes and their relation with groundwater quality as well as to get an insight into the hydrochemical
evaluation of groundwater. The high salinity coupled with groundwater level decline pose serious problems for current irrigation
and domestic water supplies as well as future exploitation. A combined hydrogeologic and isotopic investigation have been
carried out using chemical and isotopic data to deduce a hydrochemical evaluation of the aquifer system based on the ionic
constituents, water types, hydrochemical facies and factors controlling groundwater quality. The ionic speciation and mineral
dissolution/precipitation was calculated by WATEQF package software. The increase in salinity is related to the dissolution
and/or precipitation processes during the water–rock interaction and to the cationic exchange reactions between groundwater
and clay minerals. The isotopic analysis of some groundwater samples shows a similarity with the meteoric waters reflect their
short residence time and a lowest evaporation phenomenon of infiltrated groundwater. 相似文献
4.
Ayadi Rahma Trabelsi Rim Zouari Kamel Saibi Hakim Itoi Ryuichi Khanfir Hafedh 《Hydrogeology Journal》2018,26(4):983-1007
Major element concentrations and stable (δ18O and δ2H) and radiogenic (3H and 14C) isotopes in groundwater have proved useful tracers for understanding the geochemical processes that control groundwater mineralization and for identifying recharge sources in the semi-arid region of Sfax (southeastern Tunisia). Major-ion chemical data indicate that the origins of the salinity in the groundwater are the water–rock interactions, mainly the dissolution of evaporitic minerals, as well as the cation exchange with clay minerals. The δ18O and δ2H relationships suggest variations in groundwater recharge mechanisms. Strong evaporation during recharge with limited rapid water infiltration is evident in the groundwater of the intermediate aquifer. The mixing with old groundwater in some areas explains the low stable isotope values of some groundwater samples. Groundwaters from the intermediate aquifer are classified into two main water types: Ca-Na-SO4 and Ca-Na-Cl-SO4. The high nitrate concentrations suggest an anthropogenic source of nitrogen contamination caused by intensive agricultural activities in the area. The stable isotopic signatures reveal three water groups: non-evaporated waters that indicate recharge by recent infiltrated water; evaporated waters that are characterized by relatively enriched δ18O and δ2H contents; and mixed groundwater (old/recent) or ancient groundwater, characterized by their depleted isotopic composition. Tritium data support the existence of recent limited recharge; however, other low tritium values are indicative of pre-nuclear recharge and/or mixing between pre-nuclear and contemporaneous recharge. The carbon-14 activities indicate that the groundwaters were mostly recharged under different climatic conditions during the cooler periods of the late Pleistocene and Holocene.
相似文献5.
Rahim Barzegar Asghar Asghari Moghaddam Mortaza Najib Naeimeh Kazemian Jan Adamowski 《Arabian Journal of Geosciences》2016,9(2):147
A detailed hydrogeological investigation was carried out in the Tabriz plain in Iran using conventional hydrogeological field investigations and hydrochemistry. The study was carried out because the aquifers are of particular importance as they are more or less the only source of water supply available to the rural population and for agricultural and industrial activities. Analytical and numerical methods were applied to the constant rate pumping test data from the Tabriz airport and the Tabriz Power Station well fields. Two types of aquifers of different water quality were identified in the study area: an unconfined aquifer that extends over the plain and confined aquifers that are found in the deeper layers of the multilayered sediment terraces of the Aji-Chay River course. Therefore, the central part of the Tabriz plain contains both unconfined and confined aquifers, while close to the highlands, there is only an unconfined aquifer. There was evidence of minor leakage in the confined aquifers when the numerical method was used for analysis. The groundwater in the area can be identified by three main geochemical facies: Na-Cl, Ca-HCO3, and mixed Ca-Mg-Cl-SO4. The processes responsible for the hydrochemical evolution in the area fall into five categories: dissolution of evaporate minerals, precipitation of carbonate minerals, evaporation, ion exchange, and anthropogenic activity. 相似文献
6.
广汉市平原区浅层地下水化学演化及其控制因素 总被引：4，自引：0，他引：4
为在广汉市城乡规划过程中提供地下水资源开发利用的基础信息,采用矿物风化系统分析、相关性分析、主成分分析和PhreeQC反向水文地球化学模拟等方法对广汉市平原区的浅层地下水的地下水水化学组分进行分析,确定了浅层地下水的水化学演化及控制因素,完成了地下水资源的质量及时空分布特征分析。分析表明：Gibbs图显示岩石风化主导该区地下水水化学特征,风化过程产生离子和次生矿物又经历水解作用,在矿物风化系统稳定场图中显示水样中铝硅酸盐矿物逐渐趋于溶解,碳酸盐矿物处于饱和状态;PhreeQC反向水文地球化学模拟结果显示在水流模拟路径上主要发生了钙蒙脱石、钾长石溶解和高岭石、石英、钠长石的沉淀,以及Ca-Na2之间的阳离子交换吸附作用;离子相关性和主成分分析进一步的验证了溶滤作用、蒸发浓缩作用和阳离子交换吸附作用是引起浅层地下水水化学过程和矿物组成改变的主要原因。研究区地下水水质总体不会对人体健康造成不良影响。 相似文献
7.
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
8.
The present study aimed at identifying the salinity source in the groundwater of Lenjanat Plain. To do so, non-isotopic geochemical methods were employed: groundwater samples were collected seasonally from 33 wells widespread in the area, and physicochemical parameters as well as major and minor elements were measured in the 132 samples. The data collected from the field and laboratory measurements were interpreted through statistical and hydrogeochemical graphs, mass ratios and saturation indexes obtained from modeling. The results revealed that hydrogeochemical properties of the study aquifer were controlled by rock/water interactions including ion exchange, dissolution of evaporation deposits (halite and gypsum) and precipitation/dissolution of carbonates. Based on the values of Cl/Br ratio in Lenjanat groundwater (329–4,492), dissolution of evaporation deposits in aquifer was the main cause for groundwater salinity. Considering the Lenjanat groundwater geochemical properties, the data confirm the reported Cl/Br ratios for groundwater affected by the dissolution of evaporation deposits (Cl/Br > 300) and overlaps with the range of Cl/Br ratios for domestic sewage effluent groundwater. Selecting the best chemical components and their ratios in non-isotopic geochemical methods provides an accurate distinction between sources of groundwater salinity. 相似文献
9.
Use of hydrogeochemistry and environmental isotopes for evaluation of groundwater in Qingshuihe Basin,northwestern China 总被引：4，自引：0，他引：4
Hydrogeochemistry and environmental isotope data were utilized to understand origin, geochemical evolution, hydraulic interconnection, and renewability of groundwater in Qingshuihe Basin, northwestern China. There are four types of groundwater: (1) shallow groundwater in the mountain front pluvial fans, originating from recent recharge by precipitation, (2) deep paleo-groundwater of the lower alluvial plains, which was formed long ago, (3) shallow groundwater in the lower alluvial plains, which has undergone evaporation during the recharge process, and (4) mixed groundwater (shallow and deep groundwater in the plain). The main water types are Na–HCO3, which dominates type (1), and Na–SO4, which dominates types (2) and (3). Geochemical evolution in the upper pluvial fans is mainly the result of CO2 gas dissolution, silicates weathering and cation exchange; in the lower alluvial plains, it is related to mineral dissolution. The evaporative enrichment only produces significant salinity increases in the shallow groundwater of the lower alluvial plains. Shallow groundwater age in the upper plain is 10 years or so, showing a strong renewability. Deep groundwater ages in the lower plain are more than 200 years, showing poor renewability. In the exploitation areas, the renewability of groundwater evidently increases and the circulation period is 70–100 years. 相似文献
10.
Hydrochemistry of groundwater is largely determined by both natural processes, such as dissolution, cation exchange, mixing,
evaporation; and anthropogenic activities, which can affect the aquifer systems by contaminating them or by modifying their
hydrological cycle. Both natural and anthropogenic processes vary in time and space; which is reflected in groundwater hydrochemistry
variation. The objective of this study is the determination of the main hydrogeochemical processes that affect the quality
of shallow groundwaters in the Grombalia basin, located in the Cap Bon Peninsula, north-eastern Tunisia. In this area, the
chemical composition of groundwater is mostly characterized by Na–Cl–NO3–Ca water type which reveals the implication of natural and anthropogenic major factors. Natural factors are dissolution of
evaporatic minerals, i.e. halite and gypsum and cation exchange with clays, while anthropogenic factors are pollution with
industrial Sr-rich waste water and return flow of irrigation water, highly contaminated by MgSO4 and methyl-bromide fertilizers. 相似文献
11.
12.
One hundred forty-eight groundwater samples were collected from the lower part of Wadi Siham catchment area for hydrogeochemical investigations to understand the hydrogeochemical processes affecting groundwater chemistry and their relation with groundwater quality. Groundwater in the study area is abstracted from different aquifers. The study area is characterized by arid climate and extremely high relative humidity. The results indicate that groundwater in the study area is fresh to brackish in nature. The abundance of the major ions is as follows: Na+1?>?Ca+2?>?Mg+2?≥?K+1 and Cl?1?>?HCO 3 ?1 ?>?SO 4 ?2 ?>?NO 3 ?1 . Various graphical and ionic ration plots, statistical analyses, and saturation indices calculations have been carried out using chemical data to deduce a hydrochemical evaluation of the study area. The prevailing hydrogeochemical processes operating in the study area are dissolution, mixing, evaporation, ion exchange, and weathering of silicate minerals in the eastern part (recharge areas). The reverse ion exchange and seawater intrusion control the groundwater chemistry along the Red Sea coast areas and few parts of the study area. Deterioration in groundwater quality from anthropogenic activities has resulted from saltwater intrusion along the coastal areas due to groundwater overpumping and extensive use of fertilizers and infiltration of sewage water. Salinity and nitrate contamination are the two major problems in the area, which is alarming considering the use of this water for drinking. 相似文献
13.
Maurice Monjerezi Rolf D. Vogt Per Aagaard Asfaw Gebretsadik Gebru John D.K. Saka 《Applied Geochemistry》2011,26(12):2201-2214
Groundwater resources in some parts of the lower section of Shire River valley, Malawi, are not useable for rural domestic water supply due to high salinity. In this study, a combined assessment of isotopic (87Sr/86Sr, δ18O and δ2H) and major ion composition was conducted in order to identify the hydro-geochemical evolution of the groundwater and thereby the causes of salinity. Three major end-members (representing fresh- and saline groundwater, and evaporated recharge) were identified based on major ion and isotopic composition. The saline groundwater is inferred to result from dissolution of evaporitic salts (halite) and the fresh groundwater shows influence of silicate weathering. Conservative mixing models show that brackish groundwater samples result from a three component mixture comprising the identified end-members. Hence their salinity is interpreted to result from mixing of fresh groundwater with evaporated recharge and saline groundwater. On the other hand, the groundwater with low TDS, found at some distance from areas of high salinity, is influenced by mixing of evaporated recharge and fresh groundwater only. Close to the Shire marshes, where there is shallow groundwater, composition of stable isotopes of water indicates that evaporation may also be an important factor. 相似文献
14.
Hajer Ferchichi Boutheina Farhat Mohamed F. Ben-Hamouda Abdallah Ben-Mammou 《Arabian Journal of Geosciences》2017,10(23):530
The rapid urbanization and industrialization of the Manouba plain (Northeastern Tunisia), the extensive agricultural expansion and the succession of dry years during recent decades have exerted greatly load on the water needs and lead to groundwater quality degradation. The aim of this study is to evaluate the processes controlling the groundwater mineralization of the shallow aquifer for determining its suitability for drinking and agricultural purposes. For establishing that, we combine several geological, hydrological and hydrochemical data with geostatistical techniques. The samples were collected at 17 sites covering 230 km2 of the study area and analyzed for major and trace components. The total dissolved solid (TDS) content ranges from 1372 to 3999 mg/l. The results of Piper diagram indicate that Na+/Cl? and Ca2+?>?Na+/SO4 2? were the main dominant water types localized in the sloping sides of the watershed and near the saline depression; the suitability for irrigation use was also evaluated. The high concentrations of nitrates and chlorides are indicators of anthropogenic pollution, like the agricultural over application of nitrogen fertilizers and the discharge of domestic and industrial wastewater. Saturation indexes calculated by using PHREEQC (USGS) program show that groundwaters are undersaturated with evaporitic minerals (halite, gypsum) and saturated with carbonates (calcite, aragonite). The use of principal component analysis and hierarchical cluster analysis has shown that two main factors accounting 67.13% of the information of variability within the dataset confirm the existence of dissolution of evaporitic minerals and the mechanisms of nitrate increasing the salinity of the Manouba groundwater. 相似文献
15.
Isotopic and geochemical characteristics of groundwater in the Senegal River delta aquifer: implication of recharge and flow regime 总被引：3，自引：3，他引：0
Moctar Diaw Serigne Faye Willibald Stichler Piotr Maloszewski 《Environmental Earth Sciences》2012,66(4):1011-1020
Groundwater and surface water samples were collected to improve understanding of the Senegal River Lower Valley and Delta
system, which is prone to salinization. Inorganic ion concentrations and environmental isotopes (18O, 2H and 3H) in groundwater, river, lake and precipitation were investigated to gain insight into the functioning of the system with
regard to recharge sources and process, groundwater renewability, hydraulic interconnection and geochemical evolution. The
geochemical characteristics of the system display mainly cation (Ca2+ and/or Na+) bicarbonated waters, which evolve to chloride water type; this occurs during groundwater flow in the less mineralized part
of the aquifer. In contrast, saline intrusion and secondary brines together with halite dissolution are likely to contaminate
the groundwater to Na–Cl type. Halite, gypsum and calcite dissolution determine the major ion (Na+, Cl−, Ca2+, Mg2+, SO4
2− and HCO3
−) chemistry, but other processes such as evaporation, salt deposition, ion exchange and reverse exchange reactions also control
the groundwater chemistry. Both surface water and groundwater in the system show an evaporation effect, but high evaporated
signatures in the groundwater may be due to direct evaporation from the ground, infiltration of evaporated water or enriched
rainwater in this region. The stable isotopes also reveal two types of groundwater in this system, which geomorphologically
are distributed in the sand dunes (depleted isotopes) and in the flood plain (enriched isotopes). Consideration of the 3H content reinforces this grouping and suggests two mechanisms of recharge: contribution of enriched surface water in recharging
the flood plain groundwater and, in the sand dunes area where water table is at depth between 8 and 13 m, slow recharge process
characterized the submodern to mixed water. 相似文献
16.
In this study, combining interpretations of conservative dissolved ions and environmental isotopes in water were used to investigate the main factors and mechanisms controlling groundwater salinization and hydrogeochemical processes in the Eastern Nile Delta, Egypt. Hydrogeochemical and isotopic study has been carried out for 61 water samples from the study area. Total dissolved solid (TDS) contents of groundwater are highly variable rising along flowpath from the south (410 mg/L) to the north (14,784 mg/L), implying significant deterioration and salinization of groundwater. Based on TDS and ionic ratios, groundwater samples were classified into three groups. In low-saline groups, water chemistry is greatly influenced by cation exchange, mineral dissolution/precipitation, anthropogenic pollutants and mixing with surface water. Whilst, in high-saline groups, water chemistry is affected by salt-water intrusion, reverse cation exchange and evaporation. The chemical constituents originating from saline water sources, reverse ion exchange and mineral dissolution are successfully differentiated using ionic delta and saturation index approaches. The δ18O–δ2H relationship plots on a typical evaporation line, suggesting potential evaporation of the recharging water prior to infiltration. Isotope evidence concludes that the groundwater have been considerably formed by mixing between depleted meteoric water recharged under different climatic conditions and recently infiltrating enriched surface water and excess of irrigation water. The δ18O data in conjunction with chloride concentrations provide firm evidence for impact of dissolution of marine-origin evaporite deposits, during past geologic periods, on groundwater salinity in the northern region. Moreover, the relation between 14C activities and Cl? concentration confirms this hypothesis. 相似文献
17.
Geochemical characteristics of shallow groundwater in Datong basin, northwestern China 总被引：9，自引：0，他引：9
Located in semi-arid regions of northwestern China, Datong basin is a Quaternary sedimentary basin, where groundwater is the most important source for water supply. It is very important to study groundwater characteristics and hydrogeochemical processes for better management of the groundwater resource. We have identified five geochemical zones of shallow groundwater (between 5 and 80 m) at Datong: A. Leaching Zone (Zone I); B. Converging Zone (Zone II); C. Enriching Zone (Zone III); D. Reducing Zone (Zone IV); E. Oxidizing Zone (Zone V). In Zones I, II, and V and some parts of Zones III and IV, hydrolysis of albite/K-feldspar/chalcedony system and/or albite/K-feldspar/quartz system enhanced concentrations of Na+, K+, HCO3− and silicate. In Zone I, dissolution of carbonate and hydrolysis of feldspar generally controlled the groundwater chemistry. Infiltration of meteoric water promoted the formation of HCO3− in the water. In Zone II, the main geochemical processes influencing the groundwater chemistry were dissolutions of calcite and dolomite, ion exchange and evaporation. In Zones III and IV, in addition to ion exchange, evaporation and precipitation of calcite and dolomite, leaching of NaHCO3 in saline–alkaline soils dominated the water quality. Zone IV was under anoxic condition, and reduction reactions led to the decrease of SO42−, NO3− and occurrence of H2S, with the highest arsenic content (mean value of 366 μg/L), far exceeding Maximum Contaminant Level (MCL). Abnormal arsenic in the groundwater resulted in endemic disease of waterborne arsenic poisoning among local people. Zone V overlapped Zone I was intensively affected by coal mining activities. Sulfide minerals, such as pyrite, would have been oxidized when exposed to air due to coal mining, which directly added sulfate to groundwater and thus increased SO42− concentration. Oxidization of sulfide minerals also decreased pH and promoted dissolutions of calcite and dolomite. 相似文献
18.
Geochemical process regulating groundwater quality in a coastal region with complex contamination sources: Barka,Sultanate of Oman 总被引：4，自引：2，他引：2
An investigation was carried out to evaluate the geochemical processes regulating groundwater quality in a coastal region,
Barka, Sultanate of Oman. The rapid urban developments in Barka cause depletion of groundwater quantity and deterioration
of quality through excessive consumption and influx of pollutants from natural and anthropogenic activities. In this study,
111 groundwater samples were collected from 79 wells and analysed for pH, EC, DO, temperature, major ions, silica and nutrients.
In Barka, water chemistry shows large variation in major ion concentrations and in electrical conductivity, and implies the
influence of distinguished contamination sources and hydrogeochemical processes. The groundwater chemistry in Barka is principally
regulated by saline sources, reverse ion exchange, anthropogenic pollutants and mineral dissolution/precipitation reactions.
Due to ubiquitous pollutants and processes, groundwater samples were classified into two groups based on electrical conductivity.
In group1, water chemistry is greatly influenced by mineral dissolution/precipitation process and lateral recharge from upstream
region (Jabal Al-Akdar and Nakhal mountains). In group 2, the water chemistry is affected by saline water intrusion, sea spray,
reverse ion exchange and anthropogenic pollutants. Besides, high nitrate concentrations, especially in group 2 samples, firm
evidence for impact of anthropogenic activities on groundwater quality, and nitrate can be originated by the effluents recharge
from surface contamination sources. Ionic ratios such as SO4/Cl, alkalinity/Cl and total cation/Cl indicate that effluents recharged from septic tank, waste dumping sites and irrigation
return flow induce dissolution of carbonate minerals, and enhances solute load in groundwater. The chemical constituents originating
from saline water sources, reverse ion exchange and mineral dissolution are successfully differentiated using ionic delta,
the difference between the actual concentration of each constituent and its theoretical concentration for a freshwater–seawater
mix calculated from the chloride concentration of the sample, and proved that this approach is a promising tool to identify
and differentiate the geochemical processes in coastal region. Hence, both regular geochemical methods and ionic delta ensured
that groundwater quality in Barka is impaired by natural and human activities. 相似文献
19.
Major element concentrations, stable (δ18O and δ2H) and radiogenic (3H, 14C) isotopes determined in groundwater provided useful initial tracers for understanding the processes that control groundwater mineralization and identifying recharge sources in semi-arid Cherichira basin (central Tunisia).Chemical data based on the chemistry of several major ions has revealed that the main sources of salinity in the groundwaters are related to the water–rock interaction such as the dissolution of evaporitic and carbonate minerals and some reactions with silicate and feldspar minerals.The stable isotope compositions provide evidence that groundwaters are derived from recent recharge. The δ18O and δ2H relationships implied rapid infiltration during recharge to both the Oligocene and Quaternary aquifers, with only limited evaporation occurring in the Quaternary aquifer.Chemical and isotopic signatures of the reservoir waters show large seasonal evolution and differ clearly from those of groundwaters.Tritium data support the existence of recent recharge in Quaternary groundwaters. But, the low tritium values in Oligocene groundwaters are justified by the existence of clay lenses which limit the infiltration of meteoric water in the unsaturated zone and prolong the groundwater residence time.Carbon-14 activities confirm that groundwaters are recharged from the surface runoff coming from precipitation. 相似文献
20.
Influence of hydrogeochemical processes on temporal changes in groundwater quality in a part of Nalgonda district, Andhra Pradesh, India 总被引：4，自引：3，他引：1
Geochemical processes that take place in the aquifer have played a major role in spatial and temporal variations of groundwater
quality. This study was carried out with an objective of identifying the hydrogeochemical processes that controls the groundwater
quality in a weathered hard rock aquifer in a part of Nalgonda district, Andhra Pradesh, India. Groundwater samples were collected
from 45 wells once every 2 months from March 2008 to September 2009. Chemical parameters of groundwater such as groundwater
level, EC and pH were measured insitu. The major ion concentrations such as Ca2+, Mg2+, Na+, K+, Cl−, and SO4
2− were analyzed using ion chromatograph. CO3
− and HCO3
− concentration was determined by acid–base titration. The abundance of major cation concentration in groundwater is as Na+ > Ca2+ > Mg2+ > K+ while that of anions is HCO3
− > SO4
2− > Cl− > CO3
−. Ca–HCO3, Na–Cl, Ca–Na–HCO3 and Ca–Mg–Cl are the dominant groundwater types in this area. Relation between temporal variation in groundwater level and
saturation index of minerals reveals the evaporation process. The ion-exchange process controls the concentration of ions
such as calcium, magnesium and sodium. The ionic ratio of Ca/Mg explains the contribution of calcite and dolomite to groundwater.
In general, the geochemical processes and temporal variation of groundwater in this area are influenced by evaporation processes,
ion exchange and dissolution of minerals. 相似文献