File Name: appelo and postma geochemistry groundwater and pollution .zip
Hydrogeochemical investigations had been carried out at the Amol-Babol Plain in the north of Iran. Geochemical processes and factors controlling the groundwater chemistry are identified based on the combination of classic geochemical methods with geographic information system GIS and geostatistical techniques.
The results of the ionic ratios and Gibbs plots show that water rock interaction mechanisms, followed by cation exchange, and dissolution of carbonate and silicate minerals have influenced the groundwater chemistry in the study area. Three classes, namely, C 1 , C 2 , and C 3, have been classified using cluster analysis. However, salinization process had increased due to the influence of the evaporation-precipitation process towards the north-eastern side of the study area.
Groundwater plays a major role in the water supply and ecology of arid and semiarid regions. The quality of groundwater is important in order to support life [ 1 ]. Groundwater is controlled by natural and anthropogenic factors, such as geological structure, composition of precipitation [ 2 ], geochemical process, the interaction between the groundwater and aquifer minerals [ 3 ], and human activities.
The interaction of these factors result in various water types [ 4 ]. The groundwater chemistry depends on different hydrogeochemical processes that the groundwater undergoes over space and time. In arid and semiarid areas, such as the Amol-Babol Plain in the north of Iran and to the south of the Caspian Sea, several processes evaporation, transpiration, seawater intrusion, cation exchange, dissociation and precipitation minerals, oxidation reduction, and biological processes could be involved in the groundwater chemical composition at the same time.
Salinization is one of the principal water problem concerns that have become a major threat to the quality of the freshwater being suitable for human consumption. Land use activities, climate conditions, and the geological setting have a significant influence on the groundwater salinity [ 5 ]. Improper irrigation and drainage technique in arid and semiarid areas could also increase the risk of the progressive salinization of soil, because of the solute accumulation in irrigation water [ 2 , 6 ].
Several studies have indicated the role of other processes such as high evaporation rate and limited discharge [ 7 ], excessive pumping of groundwater [ 8 ], fossil seawater [ 9 ], and seawater-freshwater mixing [ 10 ] which increases the salt concentration in the groundwater. The coastal area on the north side of the Amol-Babol Plain is under increasing human pressure from population growth and the increase in the development of agricultural activities.
Groundwater resources along the shoreline could be threatened by the mixing mechanism of seawater intrusion into the freshwater, due to the over abstraction of groundwater [ 11 , 12 ]. In as much as salinization on the Amol-Babol Plain may be caused by a combination of different processes; this research was undertaken to identify the source of salinity of groundwater and determine the hydrogeochemical process involved in the salinization of groundwater in the study area.
The weathering conditions, altitude, and geological structure are different in the southern part of the study area, where the plain is restricted by the Alborz Highlands.
The hydrochemistry of the groundwater near the Highlands might be influenced through the dissolution of carbonate rocks, cation exchange, and the adsorption of dissolved ions as the dominant processes [ 1 ]. Studies of the major ions have been used to identify the hydrochemical facies of the water. Several researchers have evaluated the groundwater chemistry and consider hydrogeochemical processes by developing geochemical modelling and adopting graphical methods for the interpretation of water quality indices [ 2 , 14 — 16 ].
In recent years, multivariate statistical techniques coupled with PHREEQC software [ 17 ] and Geographical Information Systems GIS [ 18 ] have been applied to detect important information from the hydrogeochemical data in complex systems [ 4 , 19 — 21 ]. This multidisciplinary approach will be useful to identify and locate different physiochemical processes in the groundwater in complex aquifers.
The combination of hydrogeochemical tools and statistical analysis is applied to investigate the properties of groundwater among the sampling sites. The application of GIS provides a unified way to represent the physiochemical characteristic in a specific area, as well as the presentation of spatial distribution of groundwater hydrochemistry parameters in the thematic maps [ 22 ].
Although GIS is an appropriate tool to map, query, and analyse the data [ 22 ], which could be effective for the authorities to manage the natural resource in a given certain area [ 23 ], not many studied have been conducted with this method in hydrochemical evaluation of groundwater. The sustainable development of water resources in the arid and semiarid areas highly depends on the investigation of the hydrogeochemical evolution of groundwater.
Nevertheless, limited research is available regarding the hydrochemical characteristics of the Amol-Babol Plain. This study focuses on investigating the major hydrogeochemical aspects of groundwater chemistry on the Amol-Babol Plain as well as providing an overview of the spatial distribution of the groundwater ionic ratios by using GIS and interpolation techniques. It consists of a broad plain on the northern side of the Mazandaran Province which is bounded to the south by the Alborz Highlands and to the north by the Caspian Sea.
The plain has been formed by river deposits that developed alluvial fans, a flood plain, and marine deposits. The main annual temperature is about The temperature decreases from the north of the area, which is close to the Caspian Sea to the south around the Alborz Highlands [ 24 ].
Haraz, Babol, and Talar are the three largest rivers in the study area. The rivers begin from the Alborz Highlands and flow northward to the Caspian Sea. The river is a major source of agricultural activity in the region. The Babol River passes through Babol City. Moreover, the groundwater is the main source for drinking in the study area.
The Amol-Babol Plain is part of the geological unit of the Georgian-Rasht Zone situated in the north of the Alborz great fault, which extends from Georgian to Lahijan [ 25 ]. The oldest geological formation of the study area dates back to the Permian age and includes Dorud, Ruteh, and Nessan formations, which mostly consist of a limestone layer and also thin layers of shale and marl [ 25 ]. These formations mostly outcrop in the southern parts of the study area near the Haraz road.
When global de glaciation started in the Triassic age, sedimentation stopped in the Alborz area [ 25 ], and the sea level started to rise with the commencement of sedimentation during the Jurassic period.
The bedrock of the area mostly belongs to the lower to middle Jurassic formation. The lithology of the study area consists of conglomerates, sandstone, siltstone, shale, and coal seams. The late Jurassic is represented by the presence of limestone in the sediment layers. Cretaceous marl and clay cover top of the Jurassic limestone in the south and south-eastern side of the study area.
During the Quaternary period, the process of deposition developed unconsolidated clay and sandy sediments with freshwater over an extensive part of the plain [ 25 ].
Alluvial fans have been formed by the weathering of rocks, transport and deposition of sediments by the rivers. During this process, Haraz homogenous and Talar heterogeneous alluvial fans had been extended to the western and eastern side of the Amol-Babol Plain [ 26 ]. The Caspian Sea is a remnant of the Paratethys Sea, which became an enclosed water body around 5. Then within the last one million years, old sea water, which was trapped between the layers of sediment layers, was washed and discharged to the sea by the river and groundwater flows [ 25 ].
However, fossil saline water still remains in limited areas on the north eastern side of the plain, due to the weak discharge rate of the Talar River and the heterogeneous sediment layers of clay and sand in the study area [ 26 ].
Groundwater in the study area is represented by an unconfined aquifer and a confined aquifer. The groundwater tables decrease from the Highlands on the southern side to the coastal area Figure 1. The main direction of the groundwater flow is from the recharge zone Alborz Mountain in the south to the discharge area Caspian Sea in the north part of the plain Figure 2.
The hydraulic gradient varies from 10 per thousand in the southern area to 0. There are around 61, shallow and 6, deep wells on the Amol-Babol Plain. A total of groundwater samples were collected from wells during the dry and wet seasons in After pumping out for 10—15 minutes to prevent nonrepresentative samples of stagnant or polluted water [ 27 ], the analyses were undertaken within 24 hours of the sampling exercise.
The parameters, such as temperature, electrical conductivity EC , pH, total dissolved solid TDS , and dissolved oxygen DO were measured in the field immediately after sampling using a multiparameter WP series meter. The bottles were rinsed using the groundwater to be sampled.
The samples were taken and stored in the acid-washed polyethylene bottles [ 28 ]. Also, the samples were filtered using a 0. The samples were analysed for sodium, potassium, calcium, magnesium, chloride, sulfate, bicarbonate, and carbonate based on the APHA [ 28 ] procedures in the laboratory.
The anions and bicarbonate were determined by acid titration, while the chloride concentration was determined by AgNO 3 titration and the sulfate and phosphate values by spectrophotometer.
The quality of the analyses of the parameters to obtain a reliable dataset was controlled by sending the blank samples to the laboratory. Multivariate statistical analyses were applied to obtain significant information from hydro-chemical data sets in complex systems.
Chemical variables were graphically interpreted using Piper, Schoeller, and Gibbs diagrams to show the groundwater facies for the Amol-Babol Plain. Multivariate statistical methods of descriptive statistics, Pearson correlation analysis, discriminant analysis DA , and cluster analysis CA were performed as quantitative and independent methods for classification of groundwater samples and to correlate between the chemical parameters and groundwater samples.
Multivariate statistical analysis utilizes normally distributed data [ 30 ]. The data for most chemical parameters are positively skewed.
The data were then log-transformed so that it will be normally distributed Prior to the multivariate analyses, all the parameters were standardized by subtracting the mean value and dividing by the standard deviation of parameters [ 16 ]. Discriminant analysis was applied to characterize and categorize the water quality into exclusive and exhaustive groups based on the relationship between dependent variable and independent variables [ 32 ].
Linear combinations of independent variables will discriminate the groups to minimize the misclassification error [ 33 ]. DA was applied on the raw data using forward stepwise methods to determine the most significant variables that highly influenced groundwater quality [ 34 ].
For the classification of variables based on the similarities within a class and heterogeneity between the classes cluster analysis was applied on the normalized dataset by means of the Ward method [ 35 ].
Hierarchical agglomerative cluster analysis HACA was mostly used where clusters were formed sequentially, by starting from the most similar pair of objects and forming higher clusters [ 36 ]. The dendrogram provides a visual summary of the clustering process, presenting a picture of classes and their proximity. In this study, the degree of association of relationship between two variables was summarized using Pearson's correlation analysis [ 30 ]. Ordinary kriging is a method for linear optimum appropriate interpolation with a minimum square error of the un sampled location, based on the following [ 37 ]:.
The basic geostatistical tool for modelling the spatial autocorrelation of a regionalized variable is the semivariogram, which measures the average degree of dissimilarity between the unsampled values and the nearest data values [ 38 ]. The best fitting variogram model has been chosen by calculating the experimental semivariogram and fitting alternative semivariogram, using cross validation. The cluster analysis classified the groundwater samples into three general classes, namely, C 1 , C 2 , and C 3 , using cluster analysis based on the similarities among the chemical parameters involved in the groundwater quality on the plain Figure 3 a.
The level of significance of the chemical parameters of sodium, magnesium, calcium, chloride, and electrical conductivity was determined by discriminant analysis according to spatial variation of the sampling wells in the study area. Therefore, the chemical compositions of these classes were characterized by the Ca-Mg-HCO 3 water type. The Ca-HCO 3 water, which extended in the Haraz alluvial fan and the southern side of the Alborz Highlands, represented permanent hardness of the groundwater.
The groundwater samples were classified as Na-Cl type, which represented the saline water type. The spatial distribution map showed that the groundwater type gradually changed from freshwater on the south and western sides to saline water on the north-eastern side of the plain Figure 4 b. In general, the groundwater was found to be slightly acidic with pH values varying from minimum 6.
Naturally, rainwater is slightly acidic [ 40 ], due to the reaction with carbon dioxide in the atmosphere, thereby making the rainwater slightly acidic, according to 1 Table 1 :. The large variations of the EC and TDS in the groundwater were dependent on the geochemical processes and the anthropogenic activities, such as the application of fertilizers and seawater intrusion in the study area. High calcium concentration might have originated from calcite and dolomite weathering or silicate rock dissolution.
The concentration of potassium in the groundwater samples varied from 0. Calcium and magnesium were the dominant cations and bicarbonate was the dominant anion in wide areas of the western, eastern, and central sides of the plain.
Only a few samples around 2. The spatial pattern in the ratio of calcium and magnesium showed the variation from the south to the central and eastern parts of the plain Figure 6 a. The ratio was the highest towards the Alborz Highlands on the southern side, due to the increase in calcium concentration through the weathering of silicate and carbonate rocks in the recharge area. The ratio decreased with the distance from the weathering zones towards the discharge area in the Caspian Sea Figure 6 a.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Balkema Publishers, Leiden, The Netherlands. Hardcover, pp. ISBN This book presents important fundamental concepts and current knowledge of groundwater geochemistry and the interaction of water, minerals, gases,.
The Mazar-i-Sharif city is part of the Balkh province, north of Afghanistan, and its groundwater resources are developed for water supply and irrigation purposes. The main lithological units consist chiefly of evaporite, conglomerate, sandstone, siltstone, and loess. In order to evaluate the quality of groundwater in the study area, 28 samples were collected and analyzed for various ions. Chemical indices like sodium adsorption ratio, the percentage of sodium, residual sodium carbonate and permeability index were calculated.
Its groundwater resources are used mainly for crop irrigation in an agriculture dominated area. Hydrochemical and water quality data obtained through a sampling period December and analysis program indicate that nitrate pollution can be a serious problem affecting groundwater due to the use of nitrogen N fertilizers in agriculture. Considerable seasonal fluctuations in groundwater quality were observed as a consequence of agricultural practices and other factors such as annual rainfall distribution and the wadi El Kebir flow regime. The chemical composition of the water is not only influenced by agricultural practices, but also by interaction with the alluvial sediments.
Groundwater resources are often exposed to multiple sources of pollution, which may make them unfit for human consumption. As a result, comprehensive geochemical studies on groundwater status and evolution are required for a sustainable management of water resources. In the present study, 38 water samples from hand-dug wells were collected in a peri-urban area, and their physico-chemical parameters, viz.
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Ion exchange and dissolution seem to be the dominant process that alters the quality of groundwater in coastal aquifers (Appelo and Postma.Courtney M. 16.12.2020 at 00:43
To browse Academia.Dongtazipo 17.12.2020 at 08:56
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