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1.
A total of 194 groundwater samples were collected from wells in hard rock aquifers of the Medak district, South India, to assess the distribution of fluoride in groundwater and to determine whether this chemical constituent was likely to be causing adverse health effects on groundwater user in the region. The study revealed that the fluoride concentration in groundwater ranged between 0.2 and 7.4 mg/L with an average concentration of 2.7 mg/L. About 57% of groundwater tested has fluoride concentrations more than the maximum permissible limit of 1.5 mg/L. The highest concentrations of fluoride were measured in groundwater in the north-eastern part of the Medak region especially in the Siddipeta, Chinnakodur, Nanganoor and Dubhaka regions. The areas are underlain by granites which contain fluoride-bearing minerals like apatite and biotite. Due to water–rock interactions, the fluoride has become enriched in groundwater due to the weathering and leaching of fluoride-bearing minerals. The pH and bicarbonate concentrations of the groundwater are varied from 6.6 to 8.8 and 18 to 527 mg/L, respectively. High fluoride concentration in the groundwater of the study area is observed when pH and the bicarbonate concentration are high. Data plotted in Gibbs diagram show that all groundwater samples fall under rock weathering dominance group with a trend towards the evaporation dominance category. An assessment of the chemical composition of groundwater reveals that most of the groundwater samples have compositions of Ca2+–Mg2+–Cl? > Ca2+–Na+–HCO3 ? > Ca2+–HCO3 ? > Na+–HCO3 ?. This suggests that the characteristics of the groundwater flow regime, long residence time and the extent of groundwater interaction with rocks are the major factors that influence the concentration of fluoride. It is advised not to utilize the groundwater for drinking purpose in the areas delineated, and they should depend on alternate safe source.  相似文献   

2.
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3.
Groundwater of an aquifer located in the vicinity of a large coal washery near Zarand City, Iran consists of two hydrochemically differing facies, which have been informally designated as groundwater (A) and groundwater (B). Groundwater (A) is native, brackish in composition and is characterized by Na+ > Mg2+ > Ca2+ > K+ and SO4 2? > HCO3 ? > Cl? > NO3 ?. Spearman’s rank correlation coefficient matrices, factor analysis data, and values of chloro-alkaline indices, C ratio and Na+/Cl? molar ratio indicate that in the groundwater (A), the ionic load of Ca2+, Mg2+, Na+, K+, SO4 2? and HCO3 ? is derived essentially from weathering of both carbonates and aluminosilicates and direct cation and reverse cation–anion exchange reactions. Groundwater (B) is the polluted variant of the groundwater (A), brackish to saline in composition, and unlike the groundwater (A), consists of HCO3 ? as the dominant anion. In comparison with the groundwater (A), the groundwater (B) contains higher concentrations of all ions, and its average ionic load (av. = 59.74 me/L) is 1.43 times higher than that of the groundwater (A) (av. = 41.54 me/L). Additional concentrations of Ca2+, Mg2+, K+, SO4 2?, Cl? and HCO3 ? in the groundwater (B) are provided mainly by downward infiltrating water from the coal washery tailings pond and reverse cation–anion exchange reaction between tailings pond water and exchanger of the aquifer matrix during non-conservative mixing process of groundwater (A) and tailings pond water. Certain additional concentrations of Na+, K+ and NO3 ? in the groundwater (B) are provided by other anthropogenic sources. Quality wise, both groundwaters are marginally suitable for cultivation of salt-tolerant crops only.  相似文献   

4.
Groundwater survey has been carried out in the area of Gummanampadu sub-basin located in Guntur District, Andhra Pradesh, India for assessing the factors that are responsible for changing of groundwater chemistry and consequent deterioration of groundwater quality, where the groundwater is a prime source for drinking and irrigation due to non-availability of surface water in time. The area is underlain by the Archaean Gneissic Complex, over which the Proterozoic Cumbhum rocks occur. The results of the plotting of Ca2+ + Mg2+ versus HCO3 ? + CO3 2?, Ca2+ + Mg2+ versus total cations, Na+ + K+ versus total cations, Cl? + SO4 2? versus Na+ + K+, Na+ versus Cl?, Na+ versus HCO3 ? + CO3 2?, Na+ versus Ca2+ and Na+: Cl? versus EC indicate that the rock–water interaction under alkaline condition is the main mechanism in activating mineral dissociation and dissolution, causing the release of Ca2+, Mg2+, Na+, K+, HCO3 ?, CO3 2?, SO4 2? and F? ions into the groundwater. The ionic relations also suggest that the higher concentrations of Na+ and Cl? ions are the results of ion exchange and evaporation. The influences of anthropogenic sources are the other cause for increasing of Mg2+, Na+, Cl?, SO4 2? and NO3 ? ions. Further, the excess alkaline condition in water accelerates more effective dissolution of F?-bearing minerals. Moreover, the chemical data plotted in the Piper’s, Gibbs’s and Langelier–Ludwig’s diagrams, computed for the chloro-alkaline and saturation indices, and analyzed in the principal component analysis, support the above hypothesis. The groundwater quality is, thus, characterized by Na+ > Ca2+ > Mg2+ > K+: HCO3 ? + CO3 2? > Cl? > SO4 2? > NO3 ? > F? facies. On the other hand, majority of groundwater samples are not suitable for drinking with reference to the concentrations of TDS, TH, Mg2+ and F?, while those are not good for irrigation with respect to USSL’s and Wilcox’s diagrams, residual sodium carbonate, and magnesium hazard, but they are safe for irrigation with respect to permeability index. Thus, the study recommends suitable management measures to improve health conditions as well as to increase agricultural output.  相似文献   

5.
Groundwater of the unconfined aquifer (1,100 sq. km) of a two-tier coastal aquifer located in the Amol–Ghaemshahr plain, Mazandaran Province, Northern Iran, is classified into fresh and brackish water types. Fresh groundwater (FGW) samples (n = 36) are characterized by Ca2+ > Na+ > Mg2+ > K+ and HCO3 ? > Cl? > SO4 2? > NO3 ?. Spearman’s rank correlation coefficient matrices, factor analysis data, values of the C-ratio (av. = 0.89) and CAI and values of the molar ratios of Ca2+/HCO3 ?, Ca2+/SO4 2?, Mg2+/HCO3 ? and Mg2+/SO4 2? indicate that the ionic load in the FGW is derived essentially from carbonic acid-aided weathering of carbonates and aluminosilicates, saline/sea water trapped in the aquifer sediments (now admixed with the groundwater) and ion exchange reactions. Values of the CAI and Na+/Cl? molar ratio suggest that the part of the Ca2+ (±Mg2+) content in 23 FGW samples is derived from clay minerals of the aquifer matrix, and part of the Na+ content in 20, 12, and 3 FGW samples is derived, respectively, from alkali feldspar weathering, clay minerals of the aquifer matrix and rain water and/or halite. Brackish groundwater (BGW) samples (n = 4) contain Cl? as the dominant anion and their average total ionic concentration (38.65 meq/L) is 1.79 times higher than that of the FGW samples (21.50 meq/L). BGW pockets were generated by non-conservative mixing of FGW with the upconed saline water from the underlying saline groundwater zone of the semi-confined aquifer along bore wells involved in excessive extraction of groundwater from the unconfined aquifer. Groundwater belongs essentially to “high salinity, low sodium” irrigation water class.  相似文献   

6.
Investigations were undertaken into the quality of surface water and groundwater bodies within the Upper Tigris Basin in Turkey to determine their suitability for potable and agricultural use. In the study area, the majority of the groundwater and surface water samples belong to the calcium–magnesium–bicarbonate type (Ca–Mg–HCO3) or magnesium–calcium–bicarbonate type (Mg–Ca–HCO3). Chemical analysis of all water samples shows that the mean cation concentrations (in mg/L) were in the order Ca2+ > Mg2+ > Na+ > K+ and that of anions are in the order \( \text{HCO}_{3}^{ - } \) > \( \text{SO}_{4}^{2 - } \) > Cl? > \( \text{CO}_{3}^{ - } \) for all groundwater and surface water samples. The Mg2+/Ca2+ ratio ranges from 0.21 to 1.30 with most of the values greater than 0.5, indicating that weathering of dolomites is dominant in groundwater. The analysis reveals that all of the samples are neutral to slightly alkaline (pH 7.0–8.7). Groundwater and surface water suitability for drinking usage was evaluated according to the World Health Organization and Turkish Standards (TSE-266) and suggests that most of the samples are suitable for drinking. Various determinants such as sodium absorption ratio, percent sodium (Na %), residual sodium carbonate and soluble sodium percentage revealed that most of the samples are suitable for irrigation. According to MH values, all of the well water samples were suitable for irrigation purposes, but 80 and 81.82% of Zillek springs and surface water samples were unsuitable. As per the PI values, the water samples from the study area are classified as Class I and Class II and are considered to be suitable for irrigation.  相似文献   

7.
Twenty groundwater samples were collected from Enugu metropolis over two seasonal periods in order to characterize the groundwater and to determine its quality for domestic and irrigation purposes. The results show that groundwater of the area is strongly acidic to slightly alkaline in nature and varied from “soft water” to “moderately hard” water type. The major ionic trend is in the order Cl? > Na+ > HCO3 ? > K+ > Mg2+ > Ca2+ > SO4 2?and Mg2+ > Cl? > Na+ > K+ > Ca2+ > HCO 3 ?  > SO4 2? in abundance for dry and rainy seasons, respectively. The results also reveal that there is an increase in trend of the ionic concentrations during the dry season, which arises from weathering of the host rocks and anthropogenic activities. Two hydrochemical facies were identified, namely, Na+ –K+ –Cl? –SO4 2?and Ca2+ –Mg2+ –Cl? –SO4 2? , with Na+ –K+ –Cl? –SO4 2? as the dominant facies for the two seasons. Groundwater quality ranges from “very poor water” to “good water” and “water unsuitable for drinking purposes” to “good water” for the dry season and rainy season investigations, respectively. The groundwater is suitable for irrigation purposes for the two seasons.  相似文献   

8.
The present work was carried out in Nalbari district of Assam (India) with an objective to assess the quality of groundwater and to check its suitability for drinking and irrigation purposes. Groundwater samples were collected from 50 different locations during pre- and post-monsoon seasons of 2016. Results of chemical analysis revealed that mean concentration of cations varied in the order Ca2+?>?Na+?>?Mg2+?>?K+, while for anions the order was HCO3 ??>?Cl??>?SO42??>?NO32??>?F? during both pre- and post-monsoon seasons. The suitability of groundwater samples for drinking purpose was assessed by comparing the results of physico-chemical analysis of groundwater with Indian Standards. Further, its suitability for irrigation purpose was assessed by evaluating several parameters like sodium adsorption ratio (SAR), sodium percentage (Na%), magnesium ratio, Kelly’s ratio and residual sodium carbonate (RSC). The SAR values obtained for all the samples were plotted against EC values in the US Salinity Laboratory diagram, and it was revealed that the most of the samples fall under water type C2-S1 indicating medium salinity and low SAR. Further, it was found that the majority of the samples belong to Ca–Mg–HCO3 hydrochemical facies followed by Ca–Mg–Cl–SO4, whereas only a few samples belong to Na–K–HCO3 hydrochemical facies.  相似文献   

9.
Hydrogeochemical investigation of groundwater has been carried out in the coastal aquifers of southern Tamil Nadu, India. Seventy-nine dug well samples were collected and analyzed for various physicochemical parameters. The result of the geochemical analysis indicates the groundwater in the study area is slightly alkaline with moderate saline water. The cation and anion concentrations confirm most of the groundwater samples belong to the order of Na+ > Mg2+ > Ca2+ > K+ and Cl? > SO4 2? > HCO3 ?. Thereby three major hydrochemical facies (Ca–Cl, mixed Ca–Mg–Cl and Na–Cl) were identified. Based on the US Salinity diagram, majority of the samples fall under medium to very high salinity with low to high sodium hazard. The cross plot of Ca2+ + Mg2+ versus chloride shows 61 % of the samples fall under saline water category. Higher EC, TDS and Cl concentrations were observed from Tiruchendur to Koodankulam coastal zone. It indicates that these regions are significantly affected by saltwater contamination due to seawater intrusion, saltpan deposits, and beach placer mining activities.  相似文献   

10.
The present study aims to discuss the hydrogeochemical processes in the Aosta Valley region and assess the quality of its groundwater for suitability of drinking and irrigation purposes. One hundred twenty-two samples were collected from the Aosta Valley region in the years 2007 and 2008 (61 per year), and analysed for pH, electrical conductivity, total dissolved solids (TDS), total hardness, major cations and anions. The pH of the samples in both years indicated a near-neutral to alkaline nature of the groundwater. The cation and anion chemistry showed the general ionic abundance as: Ca2+ > Mg2+ > Na+ > K+ and HCO3 ?>SO4 2?>Cl?>NO3 ?>F? in both years. Ca2+-Mg2+-HCO3 ? and Ca2+-Mg2+-Cl?-SO4 2? were the dominant hydrogeochemical facies. The computed saturation indices demonstrated that the groundwater was supersaturated with respect to dolomite and calcite in both years. The groundwater chemistry of the study area was mainly controlled by the dissolution of carbonate, sulphate and silicate minerals, as well as ion exchange processes. A comparison of the groundwater quality in relation to drinking water standards showed that most of the water samples were suitable for drinking and domestic uses. The computed water quality index (WQI) values of the study area groundwater ranged from 24 to 84 in the year 2007 and from 22 to 82 in the year 2008, and all the location fell under the Excellent to Good category. Quality assessment for irrigation uses revealed that the groundwater was good to permissible quality for irrigation; however, locally higher salinity, residual sodium carbonate (RSC) and magnesium hazard (MH) restricted its suitability for irrigation at a few sites. These results will be useful in implementing future measures in groundwater resource management at regional and national level.  相似文献   

11.
Agricultural activities act as dominant polluter of groundwater due to increased fertilizers and pesticides usage. Bist-Doab region, Punjab, India, is one such region facing deterioration of groundwater quality due to usage of fertilizers. This study aims in delineating and evaluating the groundwater quality in the region. Water samples are collected from canals, reservoir, and shallow and deep groundwater. Water types in canal and reservoir in Kandi region are Mg2+HCO3 ? and Mg2+Ca2+Na+HCO3 ?, respectively. While water types of shallow and deep groundwaters are found to be of two types: Na+Mg2+Ca2+HCO3 ? and Ca2+Mg2+Na+HCO3 ?. Presence of Mg2+ in groundwater at locations adjoining canals indicates recharge due to canal. The major ion (Na+, Mg2+, Ca2+, HCO3 ?) chemistry of the region is due to weathering of rocks that are rich in sodic minerals and kankar. Deep groundwater quality in the region meets BIS and WHO standards for drinking purpose, unlike shallow groundwater which is of poor quality at many locations. Both shallow and deep groundwater with high sodium concentration (>1.5 meq/l) affect cropping yield and permeability of soil matrix. High concentration of SO4 2? and NO3 2? (>1 meq/l) in shallow groundwater at few locations indicates influence of anthropogenic (fertilizer) activity. Factor analysis indicates that the major cations, bicarbonate and chloride are derived from weathering/dissolution of source rocks. Higher concentration of nitrate and presence of sulphate in shallow groundwater at few locations is due to usage of fertilizers and pesticides.  相似文献   

12.
Assessment of groundwater quality in and around Vedaraniyam,South India   总被引：1，自引：1，他引：0  
Groundwater from 47 wells were analyzed on the basis of hydrochemical parameters like pH, electric conductivity, total dissolved solids, Ca2+, Mg2+, Na+, K+, Cl?, CO3 2?, HCO3 ?, NO3 ?, PO4 3? and F? in the Cauvery delta of Vedaraniyam coast. Further, water quality index (WQI), sodium percentage (Na %), sodium absorption ratio, residual sodium carbonate, permeability index and Kelley’s ratio were evaluated to understand the suitability of water for drinking and irrigation purposes. The result shows significant difference in the quality of water along the coastal stretch. The order of dominance of major ions is as follows: Na+ ≥ Mg2+ ≥ Ca2+ ≥ K+ and Cl? ≥ HCO3 ? ≥ CO3 2? ≥ PO4 3? ≥ F?. Na/Cl, Cl/HCO3 ratio and Revelle index confirmed that 60–70 % of the samples were affected by saline water intrusion. WQI showed that 36 % of the samples were good for drinking and the remaining were poor and unsuitable for drinking purpose. The degradation of groundwater quality was found to be mainly due to over-exploitation, brackish aquaculture practice, fertilizer input from agriculture and also due to domestic sewage.  相似文献   

13.
Groundwater in Farashband plain, Southern Iran, is the main source of water for domestic and agricultural uses. This study was carried out to assess the overall water quality and identify major variables affecting the groundwater quality in Farashband plain. The hydrochemical study was undertaken by randomly collecting 84 groundwater samples from observation wells located in 13 different stations covering the entire plain in order to assess the quality of the groundwater through analysis of major ions. The water samples were analyzed for various physicochemical attributes. Groundwater is slightly alkaline and largely varies in chemical composition; e.g., electrical conductivity (EC) ranges from 2314 to 12,678 μS/cm. All the samples have total dissolved solid values above the desirable limit and belong to a very hard type. The abundance of the major ions is as follows: Na+ > Ca2+ > Ma2+ > K+ and Cl? > SO4 2– > HCO3 ?. Interpretation of analytical data shows three major hydrochemical facies (Ca–Cl, Na–Cl, and mixed Ca–Mg–Cl) in the study area. Salinity, total dissolved solids, total hardness, and sodium percentage (Na%) indicate that most of the groundwater samples are not suitable for irrigation as well as for domestic purposes and far from drinking water standard. A comparison of groundwater quality in relation to drinking water standards showed that most of the water samples are not suitable for drinking purposes. Based on the US salinity diagram, most of samples belong to high salinity and low to very high sodium type.  相似文献   

14.
The assessment of hydrogeochemical processes that govern the water quality of inland freshwater aquifers in coastal environment, especially in Indian sub-continent, is occasionally attempted. To bridge the gap, a detail hydrochemical evaluation of groundwater occurring in coastal alluvium is attempted. Single set of high-density water sampling is done from a limited area to gain an in-depth knowledge of the processes that govern the water chemistry of the sandy aquifers. The water is of weak alkaline nature and less mineralized, EC being < 1,000 μS/cm in many samples. Major ion composition indicates that water is contaminated with excess concentration of nitrates. Ionic abundance is in the order of Cl? > Na+  > Ca2+ > HCO3 ? > SO4 2? > Mg2+  > NO3 ?. Na+ and Cl? are almost in similar proportions implying the influence of coastal climate on water quality. The water shows modest variation in their ionic assemblage among different sample points as evident from Schoeller scheme. Groundwater can be classified into three distinct facies viz. Cl?–Ca2+–Mg2+, Na+–Cl? and Ca2+–Mg2+–HCO3 ? types. The ionic assemblages, their indices, ratios and cross-plots substantiate that multiple processes were involved in the evolution of the water chemistry. Among them, silicate weathering, halite dissolution, ion exchange and base exchange played prominent role in the ion enrichment of groundwater. The aquatic chemistry is further influenced and modified by marine environment, evapotranspiration and anthropogenic inputs which is authenticated by good correlation (r 2 = 1) among the Na+–Cl?, EC–Mg2+, Na+ and Cl?. Gibbs plots established that evaporation is more responsible for contribution of minerals to the groundwater than aquifer material. Nitrate contamination can be attributed for poor sewerage disposal mechanism which is aggravated by fertilizer inputs, irrigation practices and agriculture activity. A contrasting correlation (r 2 ≥90 to <0.40) among select pairs of ions reassures dissimilar source of those ions, involvement of multiple processes and limited interaction of formation water with aquifer material.  相似文献   

15.
Excess fluoride in groundwater affects the human health and results in dental and skeletal fluorosis. Higher concentration of fluoride was noted in hard rock terrain of the south India, in the Krishnagiri district of Tamilnadu. The region has a complex geology ranging from ultra basic to acid igneous rocks, charnockite and gneissic rocks. Thirty-four groundwater samples were collected from this study area and analysed for major cations and anions along with fluoride. The order of dominance of cations is Na+?>?Mg2+?>?Ca2+?>?K+ and the anions in the following order HCO3 ??>?Cl??>?NO3 ??>?SO4 2?. It is found that nearly 58 % of the samples have more fluoride ranging from 1 to 3 mg/L. It is also noted that high fluoride waters correspond to magnesium water types. This is due to the release of fluoride from the magnesium-bearing minerals like, biotite, hornblende, etc., or weathering of apatite/hydroxyapatites found in charnockites.  相似文献   

16.
The chemistry of the rainwater indirectly reflects the composition of the ions in the atmosphere. The study of the rainwater gains its own importance as it forms the basis for the agricultural, domestic and drinking water. Twelve rainwater samples were collected along the southeastern coast of India during southwest monsoon. The samples were analyzed for the major anions (Cl?, SO4 2?, PO4 3? and HCO3 ?) and cations (Na+, K+, Ca2+ and Mg2+). The majority of the samples reflect acidic pH. The general dominance of the cations is in the order of Na+ > Ca2+ > K+ > Mg2+ and that of anions is HCO3 ? > Cl? > SO4 2? > PO4 3?. The water is classified as calcium bicarbonate to sodium bicarbonate type. The decrease of pH value also increases the pCO2. In order to study the impact of acidic and alkaline species on rainwater, correlation coefficients were determined for establishing the relationship between different ions. Good correlation was established between cations, and sulfate has no correlation with other ions and pH. Factor analysis reveals that land use pattern, marine source and methanogenesis from the tidal influenced mangroves play a major role in determining the rainwater chemistry of the region.  相似文献   

17.
The present work is an effort to develop an appraisal of the hydrogeochemical regime for the aquifers of Dhekiajuli, Sonitpur district, Assam, which is imperative considering: (i) excessive use of groundwater for irrigation; (ii) reported high arsenic (As) contamination; (iii) application of fertilizer is an inevitable process undergoing in this region to achieve higher yield owing to deteriorating water quality; and (iv) study area being the location of many tea estates of Assam, that export tea in many foreign countries. The highest As concentration of 44.39 µg/L was detected in this study (Bachasimalu and Sitalmari region), implying high As-contaminated aquifers being used for drinking and irrigation purposes in the area. The relative abundance pattern of major cations and anions was in the order of Na+ > Mg2+ > Ca2+ > K+ and HCO3 ? > Cl? > SO4 2?, respectively. Majority of the samples belong to Na+–K+–Cl?–HCO3 ? and mixed water type. Closer inspection of Piper plot reveals that a higher As value (>40 µg/L) was prevalent in HCO3 ? water type. Results of hydrogeochemical plots suggest silicate and carbonate weathering, ion exchange and anthropogenic activities to be the dominant processes governing groundwater contamination, including As which is further supported from PCA loadings. The Singri area to the east of the affected areas and adjacent to the Brahmaputra River has oxic aquifers owing to the absence of mass deposition of younger sediments, while reducing conditions prevails in the Bachasimalu and Sitalmari region. High positive correlation between As and Fe (r = 0.83**) and a negative correlation between ORP and Fe (r = ?0.68**) further add that Fe (hydr)oxides are the direct source of As release in the affected region, the mechanism being reductive hydrolysis of such (hydr)oxides. The study implies that although groundwater is suitable for irrigation use, there is a high probability of As getting into the food chain through tea and other edible plants irrigated with As-contaminated water; thus, the area has a maximum probability of facing health hazards caused by As-contaminated groundwater.  相似文献   

18.
Assessment of groundwater quality is essential to ensure sustainable use of it for drinking, agricultural, and industrial purposes. The chemical quality of groundwater of Gaya region has been studied in detail in this work to delineate the potable groundwater zones. A total of 30 groundwater samples and 2 surface water samples were collected in and around Gaya district of Bihar. The major cations follow the trend: Ca2+?>?Mg2+?>?Na+?>?K+. The domination of calcium ions in the groundwater is due to weathering of rocks. The K+ ranged between 0.2 and 47.95 ppm, suggesting its abundance the below desired limit; but some samples were found to be above permissible limit. K+ weathering of potash silicate and the use of potash fertilizer could be the source. The major anions abundance followed the order HCO 3 ? ?>?Cl??>?SO 4 2? ?>?NO 3 ? ?>?PO 4 3? . Dissolution of carbonates and reaction of silicates with carbonic acid accounts for the addition of HCO 3 ? to the groundwater and oxidation of sulphite may be the source of SO 4 2? . Principal component analysis was utilized to reflect those chemical data with the greatest correlation and seven major principal components (PCs) representing >80 % of cumulative variance were able to interpret the most information contained in the data. PC1, PC2 and PC3 reflect the hydrogeochemical processes like mineral dissolution, weathering and anthropogenic sources. PC4, PC5, PC6 and PC7 show monotonic, random and independent relationships.  相似文献   

19.
Groundwater is a precious resource for humankind not only in Nepal but also across the globe due to its diverse functions. A total of 48 groundwater samples were collected from three villages of Nawalparasi district, Nepal, during pre-monsoon and monsoon to estimate the overall groundwater quality and to identify the sources of contamination with emphasis on arsenic (As). The average concentrations of all tested groundwater quality parameters (temp., pH, EC, ORP, Ca2+, Mg2+, Na+, K+, Cl?, F?,SO4 2?, PO4 3?, HCO3 ?, NO3 ?, Cu, Ni, Mn, Cd, Pb, Fe, Zn, Cr, and As) were well within permissible limits of WHO for drinking water, except for Ni, Cd, Pb, Cr, and As. Concentration of As ranged from 60 to 3,100 μg L?1 and 155 to 1,338 μg L?1 in pre-monsoon and monsoon, respectively. The Piper diagram of the groundwater chemistry showed groundwater of Nawalparasi belongs to Ca–Mg–HCO3 and Mg–HCO3 water type with HCO3 ? as dominant ions. As content in the study area was negatively correlated with Fe in pre-monsoon, while it was positively correlated in monsoon. Furthermore, As was negatively correlated with oxidation reduction potential suggesting reducing condition of groundwater. Principal component analysis revealed seven major factors that explained 81.996 and 83.763 % of total variance in water quality in pre-monsoon and monsoon, respectively. The variance of water quality was related mainly with the degree of water–rock interaction, mineralization, and anthropogenic inputs.  相似文献   

20.
The chemical analysis of 19 water wells in Ferdows area, Northeastern Iran, has been evaluated to determine the hydrogeochemical processes and ion concentration background in the region. In the study area, the order of cation and anion abundance is Na+ > Ca2+ > Mg2+ > K+ and Cl? > SO 4 ?2  > HCO3 ? > NO3 ?, respectively, and the dominating hydrochemical types are Na–Cl. Most metal concentrations in water depend on the mineral solubility, and pH, Eh, and salinity of the solution. Their ΣREE concentrations showed excellent correlations with parameters such as TDS and pH. North American Shale Composite (NASC)-normalized REE patterns are enriched in the HREEs relative to the LREEs for all groundwaters. They all have positive Eu anomalies (Eu/Eu* = 0.752–3.934) and slightly negative Ce anomalies (Ce/Ce* = 0.019–1.057). Reduction–oxidation, complexation, desorption, and re-adsorption alter groundwater REE concentrations and fractionation patterns. The positive Eu anomalies in groundwaters are probably due to preferential mobilization of Eu2+ relative to the trivalent REEs in the reducing condition.  相似文献   

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