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1.
Detailed hydrogeochemical analysis of several samples of groundwater collected from parts of the Niger Delta, Nigeria has been carried out in an effort to assess the quality of groundwater in the area. Results obtained showed the groundwater in the area to be enriched in Na+, Ca++, Mg++, Cl, HCO 3 - , and SO 4 -- . The concentration of these ions as well as such parameters as salinity, total hardness, and TDS are below the World Health Organization (WHO) standards for drinking water. The concentration of Ca++ was found to be higher than Mg++ except in some areas very close to the coast suggesting the encroachment of saltwater. This encroachment of saltwater is further indicated by the general increase in Cl and a decreased in HCO 3 - content towards the coast and Na/Cl ratios. On the basis of the present hydrogeochemical studies, five groundwater types have been recognized to occur in the area of study. These are (1) Sodium-Calcium-Magnesium-Bicarbonate type (Na-Ca-Mg-5HCO3), (2) Iron-Calcium-Bicarbonate type (Fe-Ca-4HCO3), (3) Sodium-Calcium-Magnesium-Sulfate type ( ), (4) Iron-Chloride-Bicarbonate (Fe-Cl-HCO3), and (5) Magnesium-Chloride type (Mg-2Cl). The assemblage of groundwater types in the area shows that both compound and single groundwater types occur. The geochemical characteristics of the groundwaters are thought to be closely related to the peculiar geologic and hydrologic conditions that prevail in the Niger Delta area of Nigeria.  相似文献   

2.
The dependency of people on groundwater has increased in the past few decades due to tremendous increase in crop production, population and industrialization. Groundwater is the main source of irrigation in Shiwaliks of Punjab. In the present study the samples were collected from predetermined location as was located on satellite image on basis of spectral reflectance. Global positioning system was used to collect samples from specific locations. Principal components analysis (PCA) together with other factor analysis procedures consolidate a large number of observed variables into a smaller number of factors that can be more readily interpreted. In the present study, concentrations of different constituents were correlated based on underlying physical and chemical processes such as dissociation, ion exchange, weathering or carbonate equilibrium reactions. The PCA produced six significant components that explained 78% of the cumulative variance. The concentration of the few trace metals was found to be much higher indicating recharge due to precipitation as main transport mechanism of transport of heavy metals in groundwater which is also confirmed by PCA. Piper and other graphical methods were used to identify geochemical facies of groundwater samples and geochemical processes occurring in study area. The water in the study area has temporary hardness and is mainly of Ca–Mg–HCO3 type.  相似文献   

3.
Sewage effluent is often rich in toxic constituents leading to environmental hazard. Continuous discharge of sewage effluents into an agricultural training farm in University of Ibadan is polluting groundwater used for cultivation of vegetables and cereals, as also for drinking, thus posing risk to human health. The study area is underlain by Precambrian banded gneisses. The study is based on seven groundwater samples and twenty-three soil samples collected from seven trial pits. The samples have been analysed using AtomicAbsorption Spectrophotometric and Inductively Coupled Plasma- Emission Spectroscopy respectively.Water analyses data show that the concentrations of Fe, Pb and Cd have exceeded the WHO (2006) drinking-water quality guidelines. Correlation coefficient of water shows that the coefficient corresponding to zero has a percentage of 29, whereas 71 % of correlation is either from the same source or from different source of enrichment. The correlation analysis of soil samples shows that 92.9% of the elements have the same source. The enrichment factor and geo-accumulation analyses confirm enrichment of Cu, Cd, Fe, Pb, Zn, Sr, Ba, Mn, Ni and La concentrations contributing to the pollution. All the metals analysed in the soil sample from the farm have anthropogenic influence.  相似文献   

4.
Groundwater samples from three different states of southeastern Nigeria were analyzed for a range of physicochemical parameters and heavy metal constituents in order to determine their potability as drinking water sources. The results indicate that the physicochemical parameters (pH, temperature, TDS, TH, electrical conductivity, Cl?, NO3 ? and SO4 2?) tested for have most of their values fall within the permissible limits given by the Nigerian and World Health Organization standards for drinking water quality. The results also reveal that apart from Cu and Pb the rest of the tested heavy metals (As, Zn, Ni, total Fe, Cd and Mn) recorded values that are significantly above the maximum permissible limits for drinking water purposes and therefore have the potential to cause health impacts for long-term potable use. On the basis of principal component analysis, the sources of the measured chemical constituents are likely to be predominantly geogenic (weathering of soluble minerals in the formations) and partly anthropogenic (industrial effluent, agricultural practices and mining activities). Single-factor ANOVA tests indicated insignificant differences in the datasets within/between states or geological units. Caution or adequate treatment is generally required when utilizing the groundwater from the area for drinking purpose due to the elevated metal concentrations and rating as poor to unsuitable water quality.  相似文献   

5.
6.
矿区地下水系统水质分类判别的多元统计分析   总被引:1,自引:0,他引:1  
以某矿区地下水系统为例,对该矿区地下水水化学资料进行了多元统计分析方法耦合应用研究,主要包括利用因子分析对存在相关关系的离子变量进行空间降维处理,找出能够反映众多离子信息的基础变量(正交因子),以其作为系统聚类变量;运用系统聚类法获取能代表各地下水子系统水化学特征的典型水样;使用贝叶斯逐步线性判别分析建立地下水各子系统水化学判别模型(判别函数),并对随机检验样品进行判别归属和判别模型统计检验。结果表明:这是一种稳定性较好且切实有效的、适用于矿区地下水系统水化学分类及水源水化学判别的方法。  相似文献   

7.
8.
Groundwater is considered as one of the most important sources for water supply in Iran. The Fasa Plain in Fars Province, Southern Iran is one of the major areas of wheat production using groundwater for irrigation. A large population also uses local groundwater for drinking purposes. Therefore, in this study, this plain was selected to assess the spatial variability of groundwater quality and also to identify main parameters affecting the water quality using multivariate statistical techniques such as Cluster Analysis (CA), Discriminant Analysis (DA), and Principal Component Analysis (PCA). Water quality data was monitored at 22 different wells, for five years (2009-2014) with 10 water quality parameters. By using cluster analysis, the sampling wells were grouped into two clusters with distinct water qualities at different locations. The Lasso Discriminant Analysis (LDA) technique was used to assess the spatial variability of water quality. Based on the results, all of the variables except sodium absorption ratio (SAR) are effective in the LDA model with all variables affording 92.80% correct assignation to discriminate between the clusters from the primary 10 variables. Principal component (PC) analysis and factor analysis reduced the complex data matrix into two main components, accounting for more than 95.93% of the total variance. The first PC contained the parameters of TH, Ca2+, and Mg2+. Therefore, the first dominant factor was hardness. In the second PC, Cl-, SAR, and Na+ were the dominant parameters, which may indicate salinity. The originally acquired factors illustrate natural (existence of geological formations) and anthropogenic (improper disposal of domestic and agricultural wastes) factors which affect the groundwater quality.  相似文献   

9.
10.
The Slingram electromagnetic (EM) survey using a coil separation of 60 and 100 m was carried out in ten villages in the Akinyele area of Ibadan, southwestern Nigeria to aid in the development of groundwater. Five main rock types including an undifferentiated gneiss complex (Su), biotite-garnet schist/gneiss (Bs), quartzite and quartz schist (Q), migmatized undifferentiated biotite/hornblende gneiss (M) and pegmatite/quartz vein (P) underlie the study area. A total of 31 EM profiles was made to accurately locate prospective borehole sites in the field. Four main groups with different behavioural patterns were categorized from the EM profiles. Group 1 is characterized by a high density of positive (HDP) or a high density of negative (HDN) real and imaginary curves, Group 2 by parallel real and imaginary curves intersecting with negligible amplitude (PNA), Group 3 by frequent intersection of a high density of negative minima (FHN) real and imaginary curves, and Group 4 by separate and approximately parallel (SAP) real and imaginary curves. Qualitative pictures of the overburden thickness and the extent of fracturing have been proposed from these behavioural patterns. A comparison of the borehole yield with the overburden thickness and the level of fracturing shows that the borehole yield depends more on the fracture density than on the overburden thickness. The asymmetry of the anomaly was also found to be useful in the determination of the inclination of the conductor/fracture.
Résumé Une prospection électromagnétique Silgram (EM) utilisant une séparation de 60 et 100 m, a été réalisée sur 10 sites villageois dans la zone d’Akinyele, Ibadan, au Sud-Ouest du Nigeria, pour le développement de l’exploitation des eaux souterraines. De cette manière il a été possible de définir cinq principaux types de roches comprenant un complexe gneissique indifférencié (Su), un schiste gneissique à biotite et garnet (Bs), une quartzite et un schiste quartzitique (Q), un gneiss migmatisé à hornblende et biotite indifférenciées (M) et une veine de pegmatite et quartz recouvrant la zone d’étude. Un total de 31 profils EM a été réalisé de manière à améliorer sérieusement la localisation des forages de reconnaissance. Quatre groupes principaux ont été définis sur base de leur comportement dans les profils EM. Le Groupe 1 est caractérisé par une forte densité de courbes réelles et imaginaires, positives ou négatives (HDP ou HDN). Le Groupe 2 est caractérisé par des courbes parallèles, réelles et imaginaires, superposées à une amplitude négligeable (PNA). Le Groupe 3 rassemble les densités importantes de courbes réelles et imaginaires, d’amplitude négative minimum, fréquemment intersectées. Le Groupe 4 rassemble les courbes réelles et imaginaires, distinctes et sensiblement parallèles (SAP). Les images qualitatives de l’épaisseur de la couverture et la largeur des fractures ont pu être déterminées sur base du comportement des éléments précédemment cités. La comparaison des débits de forage, de l’épaisseur de la couche supérieure, et du degré de fracturation, montre que le débit du forage dépend plus de la densité de forage que de l’épaisseur de la couverture. L’asymétrie des anomalies a par ailleurs été très utile pour déterminer l’inclinaison des fractures conductrices.

Resumen Se llevó a cabo un levantamiento electromagnético (EM) Slingram utilizando una separación de bobinas de 60 y 100 metros en 10 comunidades en el área Akinyele de Ibadan, suroeste de Nigeria para ayudar en el desarrollo de agua subterránea. Cinco tipos de rocas principales incluyendo un complejo de gneiss no diferenciado (Su), gneiss/esquisto de granate-biotita (Bs), cuarzita y esquisto de cuarzo (Q), gneiss de hornblenda/biotita migmatizado no diferenciado (M) y vetas de cuarzo/pegmatita (P) se encuentran en el área de estudio. Se levantaron un total de 31 perfiles EM para localizar con precisión sitios prospectivos para pozos en el campo. Se distinguieron cuatro grupos principales con diferente patrón de comportamiento a partir de los perfiles EM. El Grupo 1 se caracteriza por una alta densidad de curvas reales e imaginarias positivas (HDP) o negativas (HDN); el Grupo 2 por curvas paralelas reales e imaginarias que se interceptan con amplitud despreciable (PNA); el Grupo 3 por intersección frecuente de curvas reales e imaginarias con mínimos negativos de alta densidad (FHN); y el Grupo 4 por curvas imaginarias y reales separadas y aproximadamente paralelas (SAP). A partir de estos patrones de comportamiento se han propuesto cuadros cualitativos del espesor del material superficial y la extensión de fracturamiento. Una comparación de la productividad del pozo en relación al espesor del material superficial y el nivel de fracturamiento muestra que la productividad del pozo depende más de la densidad de fracturamiento que del espesor del material superficial. También se encontró que la asimetría de la anomalía era útil en la determinación de la inclinación de la fractura/conductor.
  相似文献   

11.
 An integrated geological, geoelectrical and hydrochemical investigation of shallow groundwater occurrence in the Ibadan area, southwestern Nigeria, is presented. The primary objective was to characterise the groundwater in a typical low-latitude environment underlain by Precambrian crystalline basement complex rocks. The dominant rocks comprise suites of gneisses and quartzites. Chemical analyses of the groundwater show that the mean concentration of the cations is in the order Na>Ca>Mg>K while that for the anions is Cl>HCO3>NO3>SO4. Statistical analyses, using the product-moment coefficient of correlation, indicate positive correlations between the following pairs of parameters: TDS and conductivity (r=0.96); Na++Mg2+ and Cl (r=0.95); Na++K+ and Ca2+ (r=0.43); Na++K+ and HCO3 (r=0.17); Ca2+ and Mg2+ (r=0.74); Ca2+ and HCO3 (r=0.33); Ca2++Mg2+ and HCO3 (r=0.31) and pH and HCO3 (r=0.54). A very weak negative correlation was recorded between pH and Cl, with r=–0.003. Five groundwater groups have been identified, namely, (1) the Na-Cl, Na-Ca-Cl, Na-Ca-(Mg)-Cl; (2) the Ca-(Mg)-Na-HCO3-Cl, Na-Ca-HCO3-Cl, and Ca-HCO3-Cl; (3) the Ca-(Mg)-Na-HCO3, Ca-Na-HCO3; (4) Ca-Na-Cl-(SO4)-HCO3 and (5) the Ca-(Mg)-Na-SO4-HCO3. The different groups reflect the diversity of bedrock types and consequently also of the products of weathering. Most of the water sampled is unfit for drinking on account of the high NO3 content. It can, however, be used for irrigation purposes as the sodium hazard is low while the salinity hazard ranges from low to medium. Resistivity soundings indicate the presence of a thick weathering profile, which could be up to 60 m. Such sites should be the target for any long-term and sustainable groundwater development in the area. Received: 15 April 1998 · Accepted: 4 July 1998  相似文献   

12.
A baseline study involving analyses of subsurface water samples from the Cape Coast granitoid complex, Lower Birimian, Togo Formation and the Voltaian Group, was carried out to assess their suitability for drinking, domestic and agricultural purposes. Study results show that pH within the range (3.0 ≤ pH ≤ 6.5) constitutes 74% of the boreholes analysed, and 51% have hardness values ranging from 7.89 to 73.24 mg/l as CaCO3 and are described as soft. Total dissolved solids are less than 1,000 mg/l and generally characterized by low conductivity values, of which 95% are within the range (55 ≤ EC ≤ 1,500 μS/cm). The mean values of the major cations (Ca2+, Mg2+, Na+, K+) and anions (SO42−, Cl, HCO3) are all within the World Health Organisation (WHO) standards. Five (5) of the boreholes sampled have nitrate (NO3) contamination. Even though NO3 contamination and acidic waters exist in some of the boreholes, the majority of the boreholes are excellent for drinking and domestic purposes. Assessment of the groundwaters for agricultural irrigation revealed three main categories. These are low salinity–low sodicity (C1–S1), medium salinity–low sodicity (C2–S1) and high salinity–low sodicity (C3–S1), using the US Salinity Laboratory (USSL) classification scheme. As much as 95% of the samples plotted in the ‘excellent to good’ and ‘good to permissible’ categories on the Wilcox diagram. The groundwater in the study area may therefore be regarded as good for irrigation activities. The major identifiable geochemical processes responsible for the evolution of the various ions are mineral weathering and chemical reactions.  相似文献   

13.
为实现地下水水源地的科学保护,识别水源地可能的污染源,通过采集吴忠市金积水源地保护区及周边16个水井地下水样品,依据采样测试分析结果,遵循连续性和代表性原则,选择了电导率、溶解性总固体、总硬度、浊度、溶解氧、氟化物、亚硝酸盐和细菌总数等8个指标进行多元统计分析。采用因子分析法,提取出4个公因子,利用因子得分进行多元线性回归,实现对金积水源地可能的地下水污染源的识别。结果表明,因子分析提取出的4个公因子,解释了所选样本总方差的96.979%,其中第一公因子代表蒸发浓缩作用,第二公因子代表粪便污染,第三公因子代表含氟矿物的溶解和工业污染,第四公因子代表自然作用,且各污染因子对不同采样点的污染程度不同,四个公因子对地下水水质的贡献率分别为:42.63%,29.23%,22.40%和5.74%。  相似文献   

14.
Multivariate statistical analysis has been widely used for hydrogeochemical characterization of groundwater quality. In this study, hydrochemical data from three hydrological basins were used and two methods (factor and cluster analyses) were applied. The first area is the coastal area of Eastern Thermaikos Gulf where groundwater is influenced by seawater intrusion and geothermal fluids. The other two areas are the inland basins of Gallikos and Perdikas in which agricultural and industrial activities constitute the main anthropogenic pollution sources of groundwater. Initially, the aforementioned methods were applied for each area separately and resulted in a different number of significant factors and clusters, while the natural and anthropogenic influences were spatially determined in each area. Additionally, factor and cluster analyses were applied coupling data from all areas. Therefore, five clusters and three major factors were determined distinguishing the hydrochemical processes and impacts from anthropogenic activities in more detail. It is worth mentioning that the application of cluster analysis in the coupled groundwater samples of all studied areas resulted beneficially in the most hydrochemically complex area. Salinization dominates in the coastal area, while in Gallikos and Perdikas basins high concentrations of NO3 occur mainly due to agricultural activities and small livestock units. The numerous hydrochemical samples are identified as the main issue for the higher discretization and reliability of the second approach. Nevertheless, this study is associated with a number of limitations of multivariable statistical analysis regarding extreme concentrations of Cl and Na. This issue stimulates further research in overcoming and understanding these drawbacks.  相似文献   

15.
Geoelectrical resistivity techniques are increasingly being applied in addressing a wide range of hydrological, environmental, and geotechnical problems. This is due to their effectiveness in near-surface characterization. In the present study, a suite of vertical electrical soundings (VESs) was integrated with 2D geoelectrical resistivity and time-domain induced polarization (IP) imaging to characterize the near-surface and delineate the underlying aquifer in a sedimentary terrain. The geophysical survey was conducted as part of preliminary studies to evaluate the potential of groundwater resource in Iyana-Iyesi and Canaan Land area of Ota, southwestern Nigeria. A high-yield confined sandy aquifer overlain by a low-yield aquitard was delineated; overlying the aquitard is a very resistive and thick layer that is predominantly composed of kaolinitic swelling clay intercalated with phosphate mineral.  相似文献   

16.
The central region of Saudi Arabia is underlain by thick sedimentary formations belonging to the Mesozoic and Cenozoic era. These sedimentary formations form a prolific aquifer supplying groundwater for agricultural and domestic usage in and around Riyadh. The region south of Riyadh City is well known for agricultural activities. Wadi Sahba, which is an eastward extension of Wadi Nisah, has readily available groundwater resources in the Cretaceous Biyadh sandstone aquifer to sustain agricultural activities. The objective of the present study was the hydrochemical assessment of groundwater in the area to understand the main hydrological processes which influence groundwater chemistry. To achieve this objective, 20 groundwater samples were collected from agricultural farms in the Wadi Sahba in central Saudi Arabia, and the major physiochemical constituents were analyzed and interpreted. The average TDS value of the analyzed samples is 1578.05 mg/l, whereas the average EC concentration is 3220.05 μS/cm. Groundwater facies classification inferred from the Piper plot shows that groundwater in the study area belongs to the Ca-SO4-Cl type and Ca-Na-SO4-Cl type. The Ca-SO4-Cl type of groundwater facies is influenced mainly by gypsum dissolution and base ion exchange, whereas the Ca-Na-SO4-Cl type is influenced by gypsum and halite dissolution. All the groundwater samples are undersaturated with respect to these two principal mineral phases. The Q-mode cluster analysis results in two main groups of groundwater samples, mainly based on the TDS content. Cluster 1 has an average TDS value of 1980 mg/l, whereas cluster 2 has an average TDS of 1176 mg/l. The groundwater facies identified through the Piper plot reflects the major hydrological processes controlling groundwater chemistry in the area and was found to be more useful in this study as compared to cluster analysis.  相似文献   

17.
Hydrogeologically, faults may impede, conduit, exert no influence, or may play a combination of these roles on groundwater flow. The object of this paper is to study the hydrogeological role of the Tabarteh fault, which is located on the border of Zagros and Central Iran tectonic zones in an alluvial aquifer. The recorded data of water table levels, chemical parameters, and discharge rate of wells, in addition to geological maps and geophysical results, were collected and evaluated. The outcrop of travertine in limited areas and the emergence of a few small springs within the alluvium show a barrier role of the fault in the groundwater flow. The spatial analysis of chemical components, head time series, and groundwater flow direction assessment demonstrated that the fault acts as both a barrier and a non-barrier in different sections. The multivariate statistical methods of cluster and discriminant analyses also confirm the dual role of the fault.  相似文献   

18.
Thermal groundwater is currently being exploited for district-scale heating in many locations world-wide. The chemical compositions of these thermal waters reflect the provenance and circulation patterns of the groundwater, which are controlled by recharge, rock type and geological structure. Exploring the provenance of these waters using multivariate statistical analysis (MSA) techniques increases our understanding of the hydrothermal circulation systems, and provides a reliable tool for assessing these resources.Hydrochemical data from thermal springs situated in the Carboniferous Dublin Basin in east-central Ireland were explored using MSA, including hierarchical cluster analysis (HCA) and principal component analysis (PCA), to investigate the source aquifers of the thermal groundwaters. To take into account the compositional nature of the hydrochemical data, compositional data analysis (CoDa) techniques were used to process the data prior to the MSA.The results of the MSA were examined alongside detailed time-lapse temperature measurements from several of the springs, and indicate the influence of three important hydrogeological processes on the hydrochemistry of the thermal waters: 1) salinity and increased water-rock interaction; 2) dissolution of carbonates; and 3) dissolution of sulfides, sulfates and oxides associated with mineral deposits. The use of MSA within the CoDa framework identified subtle temporal variations in the hydrochemistry of the thermal springs, which could not be identified with more traditional graphing methods, or with a standard statistical approach. The MSA was successful in distinguishing different geological settings and different annual behaviours within the group of springs. This study demonstrates the usefulness of the application of MSA within the CoDa framework in order to better understand the underlying controlling processes governing the hydrochemistry of a group of thermal springs in a low-enthalpy setting.  相似文献   

19.
The aim of this work is to evaluate the hydrogeochemical characteristics of groundwater in parts of the lower Benue Through in Nigeria as well as to evaluate the variation in groundwater chemistry data and the suitability of the groundwater for drinking and other domestic purposes. This was based on chemical analyses of 44 water samples from existing wells and boreholes in the study area. From the statistical analysis (wide ranges, median and standard deviation), it is obvious that there are significant variations in the quality/composition of groundwater in the period of sampling. The calculated SAR, Na% and RSC values indicated that the water is of excellent to good quality and is suitable for irrigation. Na and HCO3 are dominant with respect to the chemical composition of the groundwater. On the basis of water chemistry, hydrochemical indices and factor analysis the dominant controls or processes affecting the distribution of geochemical variables in the study area have been shown to be water/rock interaction which is mainly controlled by carbonate and silicate dissolution as well as anthropogenic influence to a lesser extent. Additional processes include cation exchange reactions and reverse ion exchange to a minor extent.  相似文献   

20.
In order to assess the impact of coal mining on groundwater quality in Talcher Coalfield area, seventeen groundwater samples for pre and post monsoon seasons were collected from borewells/dugwells and analysed for major ions and trace elements. Water quality analysis of major ions and trace elements shows elevated concentration in few groundwater samples. The water quality data was analysed using multivariate statistical techniques viz., factor analysis and cluster analysis. The result clearly shows that the variation in the season is due to recharge of rain water during monsoon. The factor and cluster analysis brought out impact of intensity by mining activity on groundwater regime. Discharge of mining seepage effluents and its interaction with the groundwater contaminate the surrounding groundwater regime. Multivariate statistical techniques are potential tools and provide greater precision for identifying contaminant parameters linkages with mining environment.  相似文献   

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