Characterizing Groundwater Quality Research Articles

GROUNDWATER POLLUTION SOURCE USING PRINCIPAL COMPONENT ANALYSIS IN GUELMA PLAIN, NORTHEAST ALGERIA

This study was conducted in the agricultural region of Guelma, located in northeastern Algeria, where groundwater is the main source of water for human consumption, agriculture, and industry. The objective was to characterize groundwater quality and identify potential pollution sources using multivariate statistical methods, including Principal Component Analysis (PCA), correlation matrix, and the Piper diagram. The analyses revealed strong correlations between certain ions, such as sodium and chloride, suggesting carbonate dissolution processes, such as calcite and dolomite, leading to increased water hardness. The Piper diagram allowed for the classification of water types based on the relative concentrations of major cations (Ca²⁺, Mg²⁺, Na⁺+K⁺) and anions (Cl⁻, SO₄²⁻, CO₃²⁻+HCO₃⁻), showing a predominance of mixed hydrochemical types influenced by both natural and anthropogenic processes.PCA then simplified the interpretation by identifying the most influential variables that could serve as key indicators for the continuous monitoring of water quality. Overall, the results indicate that groundwater chemistry in this region is strongly influenced by human activities and local geological conditions, highlighting the need for sustainable management and continuous monitoring to protect this vital resource.

Hydrogeochemical and isotopic assessment for characterizing groundwater quality in the Mitidja plain (northern Algeria).

Coastal aquifer overexploitation represents a concerning trigger for water salinization around the world and especially in arid and semi-arid regions along with urban growth and urbanization, as well as land use human-induced changes. This study aims to assess the groundwater quality in the Mitidja alluvial aquifer (northern Algeria) along with its suitability for domestic and agricultural utilizations. A hydrogeochemical approach, based on the interpretation of groundwater physiochemical parameters (EC, pH, dry residue, Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, and NO3-) collected during the wet and dry periods for the years 2005 and 2017 along with an isotopic characterization, including stable isotopes to identify the recharge sources for the samples collected in October 2017, has been proposed. The results show the presence of three dominant hydrochemical facies: (i) calcium chloride, (ii) sodium chloride, and (iii) calcium bicarbonate. Groundwater mineralization and salinization are so ascribable carbonates and evaporitic dissolution, especially during the dry periods, and to the presence of seawater. Ion exchange significantly affects groundwater chemistry along with human activities which directly or indirectly contribute in raising groundwater salts concentration. Specifically, NO3- concentrations are very high in the eastern portion of the study area which is exposed to fertilizers pollution where also the Richards classification pointed out the necessity of limit water utilization for agricultural use. The δ2H = f(δ18O) diagram indicates that the recharge origin for this aquifer is mainly due to the oceanic meteoric rainwater from the Atlantic and the Mediterranean Sea. The methodology proposed in this study can be applied in the similar worldwide coastal areas in order to contribute and sustainable water resource management in these regions.

Characterizing groundwater quality for a safe supply of water using WQI and GIS in Bahir Dar city, northwest Ethiopia

Abstract Although both urban and rural residents benefit from drinking enough high-quality water in the right amounts, the degree of contamination from artificial sources has been increasing. The study aims to assess the quality and availability of groundwater potential in Bahir Dar City using geographic information systems (GIS)-based ordinary kriging (OK) and analytical hierarchy process methods, respectively. The concentrations of pH, alkalinity, Escherichia coli, nitrite manganese, and iron in the groundwater of built-up areas were found to exceed the limits set by the World Health Organization. The groundwater quality distribution contained 69.6% of good water, 19.6% of the excellent class, and 10.8% of the poor class. The high potential of groundwater, particularly in the Lake Tana shoreline sedimentation areas, revealed the poor quality class. The results suggest that improving groundwater quality should be prioritized in areas with high potential groundwater availability.

Hydrogeochemical and isotopic assessment for characterizing groundwater quality and recharge processes in the Essaouira Basin, Northwestern Morocco

Hydrogeochemical and isotopic assessment for characterizing groundwater quality and recharge processes in the Essaouira Basin, Northwestern Morocco

Hydrogeochemical Characterization of Groundwater Quality in Parts of Amroha District, Western Uttar Pradesh, India

The present work attempts to characterize groundwater quality and ascertain its suitability for drinking and agricultural practices using different indices. A total of 122 sub-surface water samples were collected from the Amroha district of Uttar Pradesh, India, in the pre and post-monsoon season 2018 (61 samples of each season). The quality of groundwater observed from the study region has a slightly acidic to alkaline character with moderately hard type water. The order of the dominant ions is Na + > Ca 2+ > Mg + > K + and HCO − 3 > Cl − > SO 4 2 − > NO − 3 > F − in the pre-monsoon season while Na + > Mg + > Ca 2+ > K + and HCO − 3 > SO 4 2 − > Cl − > NO − 3 > F − in the post-monsoon season. A few samples show a higher concentration of Nitrate and Fluoride. The correlation coefficient shows that EC is positively correlated with TDS, Cl − , Ca 2+ , Mg + , and Total Hardness. The WQI studies revealed that about 52.45%, 36.07%, and 11.48% samples denoted excellent, good, and poor water quality, respectively, in the pre-monsoon season. About 52.45%, 45.9%, 1.63% of groundwater samples fell under excellent, good, and poor water quality in the post-monsoon season. The Piper diagram depicts Ca–HCO 3, mixed Ca-Na-HCO3, Na Cl, and mixed Ca-Mg-Cl facies in the water samples. Chloro-alkaline indices show negative values, which indicates that most parts of the study area exist in the discharge zone and base ion exchange processes occurred in the area. The position of the sample on the Gibbs diagram revealed that the rock-water interaction and evaporation of dissolved formation are the major governing process of water chemistry. Irrigation water quality indices revealed that the water quality for irrigation uses is mainly excellent to permissible type. The result of the Corrosivity ratio shows that about 24.5% of groundwater of the study area can be transported only through PVC pipes. • Groundwater quality assesses that most of the groundwater samples are suitable for drinking purposes except few samples are unsuitable for drinking purposes. • The WQI studies revealed that about 52.45%, 36.07%, and 11.48% samples of groundwater are excellent water, good water, and poor water quality, respectively in the pre-monsoon season. While about 52.45%, 45.9%, 1.63% groundwater samples show excellent water, good water, and poor water quality in the post-monsoon season. • The piper trilinear diagram shows the dominant facies types are Ca–HCO 3 followed by mixed Ca-Na-HCO3, Na Cl, and mixed Ca-Mg-Cl type categories. • The position of the sample on the Gibbs diagram revealed that the rock-water interaction and evaporation of dissolved formation are the major governing process of water chemistry. • Irrigation water quality indices revealed that the groundwater samples for irrigation purposes are excellent to permissible type.

Challenges to the Use of a Base of Fresh Water in Groundwater Management: Total Dissolved Solids vs. Depth Across California

According to the California Sustainable Groundwater Management Act, the bottom of a basin, and subsequently the depth to which groundwater is managed, can be defined through physical or geochemical qualities of the aquifer. Total dissolved solids (TDS) concentrations are most frequently used to define the basin bottom. However, upper limits in TDS concentrations for “fresh” and “useable” groundwater can range from 1,000 to 10,000 mg/L. To evaluate the applicability of using TDS concentrations to delineate depths subject to sustainable groundwater management, we analyze 216,754 TDS measurements throughout the state of California. We find major challenges to reasonably estimating the BFW with our dataset in 73% of California due to data insufficiencies or complexity introduced by non-montonic TDS-depth relationships. We estimate the BFW in 22% of the Central Valley, a key agricultural region with large groundwater demands and many critically overdrafted groundwater subbasins. Using a TDS limit of 3,000 mg/L, where possible, we estimate the shallowest BFW in the Central Valley to be 155 m below ground surface and the deepest BFW to be 589 m below ground surface. We find that the base of brackish water (TDS < 10,000 mg/L) can extend more than 500 m deeper than the BFW in 78% of the Central Valley where we are able to estimate the BFW, which corresponds to 2% of California. There is a need to evaluate alternative strategies for defining groundwater subject to sustainable management, which likely involves additional measurements and analysis to better characterize groundwater quality with depth throughout California.

Comprehensive assessment of groundwater quality using heavy metal pollution indices and geospatial technique: a case study from Wanaparthy watershed of upper Krishna River basin, Telangana, India

The present study is to characterize groundwater quality using heavy metal pollution indices and geospatial variations. A total of 58 samples from hand pump/submersible bore wells were collected from the Wanaparthy watershed of the upper Krishna River basin according to the grid size (5×6 km2). The trace elements’ concentration in groundwater samples are found in the order of Zn (38.67%) > B (32.67%) > Ba (13.59%) > As (8.49%) > Hg (3.71%) > Cr (1.28%) > Ni (0.52%) > Cd (0.47%). Among these trace elements, arsenic (22.4%) and mercury (5.1%) were found above the permissible limits of WHO drinking water guideline values. A positive correlation between TH versus EC/TDS indicates the presence of trace elements due to chemical reaction (rock–water interaction). Arsenic correlation with EC/TDS/TH indicates artificial intervention. Drainage network analysis enumerates high concentration of parameters at near or joining to upper order of drainage system, which might be due to input of runoff water (interaction of variable rocks composition) and later stage infiltration to subsurface and reached to an aquifer. Heavy metal pollution index (HPI) showed 86.2% of samples are in the category of low class, whereas 12.07% of samples fall within medium class. According to metal index (MI) classification, 12.07% samples are in very pure, 24.14% samples are pure, while the remaining 63.79% samples are in the slightly to strongly affect category. This study suggested the main source of trace elements in groundwater might be from the dominant granitoid rocks because the area is mostly devoid of industrialization.

Hydrochemical and isotopic assessment for characterizing groundwater quality and recharge processes under a semi arid area: Case of the Haouz plain aquifer (Central Morocco)

The Haouz plain aquifer is one of the most important aquifers in Morocco. It is supporting so many activities tightly connected to the local and national socioeconomic development (agriculture, tourism, industry). The recurrent drought the region has been experiencing, had led to a major mobilization of groundwater to meet human needs and socioeconomic objectives. A hydrogeochemical, isotopic and statistical study based on field data was conducted to understand the functioning of the aquifer, to characterize the processes controlling the groundwater's chemistry, as well as identify areas presenting water salinity anomalies. The objective of this study is to develop a conceptual model of functioning of the Haouz aquifer, leading to a better comprehension of the spatial evolution of mineralization regarding the geological frame and the current context of exploitation to evaluate groundwater suitability for domestic and agricultural use. The Plio-Quaternary aquifer water-table contours map showed a flow direction from the High Atlas Mountains, in the south (recharge zone) towards the Tensift bed river in the northwest part of the region. Physico-chemical analysis showed that electrical conductivity are essentially controlled by the chloride and sodium ions and varies over a wide range from 326 to 6800 μS/cm. Regarding irrigation, poor groundwater quality was defined specially near Tensift River in the north of the study area. Stable isotopes contents of water, range respectively from −8.35 to −5.26‰ for δ18O and from −54.4 to −32.4‰ for δD. The recharge altitude of the aquifer was estimated between 860 and 2110 m, following an altitudinal gradient of 0.25% per 100 m.

Hydrogeochemical characterization and quality assessment of groundwater using self-organizing maps in the Hangjinqi gasfield area, Ordos Basin, NW China

Abstract Water resources are scarce in arid or semiarid areas, which not only limits economic development, but also threatens the survival of mankind. The local communities around the Hangjinqi gasfield depend on groundwater sources for water supply. A clear understanding of the groundwater hydrogeochemical characteristics and the groundwater quality and its seasonal cycle is invaluable and indispensable for groundwater protection and management. In this study, self- organizing maps were used in combination with the quantization and topographic errors and K-means clustering method to investigate groundwater chemistry datasets. The Piper and Gibbs diagrams and saturation index were systematically applied to investigate the hydrogeochemical characteristics of groundwater from both rainy and dry seasons. Further, the entropy-weighted theory was used to characterize groundwater quality and assess its seasonal variability and suitability for drinking purposes. Our hydrochemical groundwater dataset, consisting of 10 parameters measured during both dry and rainy seasons, was classified into 6 clusters, and the Piper diagram revealed three hydrochemical facies: Cl-Na type (clusters 1, 2 and 3), mixed type (clusters 4 and 5), and HCO3-Ca type (cluster 6). The Gibbs diagram and saturation index suggested that weathering of rock-forming minerals were the primary process controlling groundwater chemical composition and validated the credibility and practicality of the clustering results. Two-thirds of 45 groundwater samples were categorized as excellent- or good-quality and were suitable as drinking water. Cluster changes within the same and different clusters from the dry season to the rainy season were detected in approximately 78% of the collected samples. The main factors affecting the groundwater quality were hydrogeochemical characteristics, and dry season groundwater quality was better than rainy season groundwater quality. Based on this work, such results can be used to investigate the seasonal variation of hydrogeochemical characteristics and assess water quality accurately in the others similar area.

Hydrogeochemical and isotopic assessment for characterizing groundwater quality and recharge processes in the Lower Anayari catchment of the Upper East Region, Ghana

The Lower Anayari Catchment (LAC) groundwater system of the upper east region contributes substantially to the populace’s socioeconomic development. LAC is well distinguished for intense farming activities. This study sought to assess the quality and processes/activities that impact on the groundwater chemistry in the catchment. Forty-one (41) samples, comprising boreholes and hand-dug wells were sampled from six (6) prime communities (Kulwase, Manyoro, Mirigu, Nakolo, Paga and Pungu) for physico-chemical and stable isotopes analysis. Hydrochemistry, ionic ratios, principal component analysis (PCA), geostatistics and stable isotopes (δ18O and δ2H) approaches were applied to construe the hydrogeochemistry of the groundwater system. Utilizing PCA and geostatistics, two factors controlling groundwater quality were depicted as; (a) V1- the dissolution of silicate minerals and (b) V2- agrochemicals/domestic waste. Piper Trilinear plot identified two hydrochemical facies, namely, Ca-Na-HCO3 and Na-Ca-HCO3. Cation exchange processes and silicate weathering/dissolutions are main drivers of the groundwater chemistry. Stable isotopes suggests groundwater in LAC is mainly of meteoric origin and a well-mixed system. However, few deviations of groundwater isotopic signatures from GMWL were observed suggesting evaporation before recharge or recharge occurring from an enriched source.

Hydrochemical characteristics and water quality assessment of groundwater in the Yishu River basin

Groundwater is the primary source of water for human development in the Yishu River basin, and therefore characterizing groundwater quality is essential for sustainable development of groundwater resources in the region. This study aimed to determine the hydrochemical characteristics and water quality of groundwater in the Yishu River basin by sampling 45 wells in October 2016 and May 2017. Hydrochemical characteristics of groundwater were determined using integrated hydrochemical analysis and the groundwater quality was evaluated based on the water quality index (WQI). Groundwater of the Yishu River basin was characterized as weak alkaline hard water with mean concentrations of total hardness and total dissolved solids of less than 500 mg L−1 and 1000 mg L−1, respectively, and the principal chemical components of groundwater were higher in 2016 than in 2017. A Piper diagram showed that 64.4% of the water samples contained Ca–HCO3 type water and 27% contained mixed water (27%). The dominant processes driving the chemical composition of groundwater were found to be dissolution of silicate and carbonate minerals and cation exchange. The saturation index indicated that carbonate minerals were supersaturated, whereas gypsum, fluorite, and halite were unsaturated. The WQI indicated good groundwater quality in the Yishu River basin, with only one water sample classified as having "poor" water quality in 2016 and 2017, respectively. However, these samples contained high nitrate concentrations (> 200 mg L−1), which may be the result of domestic sewage discharge and/or the use of agricultural fertilizers.

Anthropogenic Effects on Hydrogeochemical Characterization of the Shallow Groundwater in an Arid Irrigated Plain in Northwestern China

Many irrigated plains in arid and semi-arid regions have groundwater quality issues due to both intensive human activity and natural processes. Comprehensive studies are urgently needed to explore hydrogeochemical evolutions, investigate possible pollution sources, and understand the controls on groundwater compositions in such regions. Here, we combine geostatistical techniques and hydrogeochemical assessments to characterize groundwater quality over time in the Yinchuan Plain (a typical irrigated plain in China), using 12 physicochemical variables derived from sampling in 600 and 602 wells in 2004 and 2014, respectively. Our results show that groundwater-rock interactions and evaporation are the key natural factors controlling groundwater compositions. Hydrogeochemical water types in both 2004 and 2014 were Ca-HCO3, Na-Cl, and mixed Ca·Mg-Cl. Along with the hydrogeochemical compositions, we used ionic ratios and the saturation index to delineate mineral solution reactions and weathering processes. Dissolution of gypsum, halite, fluorite, and mirabilite, along with silicate weathering and cation exchange, were identified in the study area. Our results indicated rising ion concentrations in groundwater, which could be the result of anthropogenic influences. Increasing total hardness and nitrates over the study period were most likely caused by agricultural activity and the discharge of waste water from human residential areas.

Characterizing groundwater quality and seawater intrusion in coastal aquifers of Nagapattinam and Karaikal, South India using hydrogeochemistry and modeling techniques

A severe problem of water supply in eastern coastal India is the saline water intrusion into aquifers due to growing industrialization, urbanization, groundwater withdrawals and sea-level rise. The present study investigated the groundwater quality and sea intrusion in a coastal area of southern India using different techniques. A total of 122 groundwater samples were collected during May 2014 representing summer (SUM) and August 2014 representing southwest monsoon (SWM), and analyzed for 12 chemical parameters (Na+, K+, Ca2+, Mg2+, Cl−, SO42−, HCO3−, NO3−, F− PO4−, Si and TDS). Water quality index (WQI) was used to determine the groundwater quality. The WQI suggests that more samples during SWM are classified as poor quality than in SUM due to multiple factors seawater intrusion, ion exchange, excess withdrawal, sewages impact and agricultural activity. The spatial of Cl−, EC and WQI indicate that Cl− and EC related to poor quality groundwater. Saline water mixing index indicates greater percentage (35%) of samples during SWM, influenced by seawater intrusion noted toward western and eastern localities of the study area. The SEAWAT model attempted describes seawater intrusion noted along the eastern stretches of the study area owing to excess withdrawal and simulation for 50 years suggests further migration inland.

Impact of landuse on groundwater quality of Bangladesh

Groundwater pollution is a major concern in water resources management across the world. The objective of this study is to characterize groundwater quality and identify the impact of landuse on groundwater quality of Bangladesh. Total of 113 groundwater samples, collected from shallow aquifers at different locations of Bangladesh were analysed to estimate eight standard groundwater quality indices namely, sodium absorption ratio (SAR), soluble sodium percentage (SSP), residual sodium bi-carbonate (RSBC), permeability index (PI), total hardness (TH), magnesium adsorption ratio (MAR), Kelly’s ratio (KR) and total dissolved solids (TDS). The results showed that the SAR in groundwater of Bangladesh varies between 1 and 818, SSP between 9 and 99%, RSBC between − 13 and 719 meq/L, PI between 21 and 112%, TH between 233 and 19400 meq/L, MAR between 5 and 74%, KR between 0.06 and 135 meq/L, and TDS in the range of 51–15200 mg/L. Significant differences in groundwater quality indices between agricultural and forest lands were observed. The study revealed that higher amount of total dissolved salt in groundwater was due to sea water intrusion into the coastal aquifer. Relation between agriculture and groundwater quality suggests that though the nitrate concentration in groundwater was less than permissible level, it might increase in future due to extensive use of nitrogen-based chemical fertilizers in agriculture.

Evaluating groundwater quality for irrigated agriculture: spatio-temporal investigations using GIS and geostatistics in Punjab, Pakistan

Groundwater is cornerstone of global food production, and its quality plays a vital role in crop development. Success of agriculture in Pakistan relies heavily on groundwater because of reduced surface water supplies and rainfalls. The current study was conducted to assess the spatio-temporal quality of groundwater in the Lower Chenab Canal (LCC) east area with emphasis on characterizing groundwater quality zones for irrigation applications. Groundwater samples from 289 observation wells were collected and chemically analyzed. A geostatistical approach using kriging interpolation was applied to express spatial variation and minimize estimation error in data. Three water quality parameters, electrical conductivity (EC), sodium absorption ratio (SAR), and residual sodium carbonate (RSC), were utilized to develop groundwater quality maps for two seasons including pre-monsoon and post-monsoon. To describe the spatial autocorrelation, suitable semivariogram models were identified and cross validated. The exponential model gave the best results for EC and RSC, whereas the spherical model was found to be the best fit for SAR. The overlay analysis was performed to create composite water quality maps according to which 40% LCC area is showing good groundwater quality for irrigation, 49% is exhibiting marginal quality, and 10% unsuitable during pre-monsoon and post-monsoon seasons. Groundwater quality is 100% good for Sultanpur irrigation subdivision, and only 3.75% is good for Paccadala subdivision. The results of the study may provide guidelines for the planners/policy makers to devise area-specific strategies for sustainable groundwater use.

Characterizing groundwater quality ranks for drinking purposes in Sylhet district, Bangladesh, using entropy method, spatial autocorrelation index, and geostatistics.

Drinking water is susceptible to the poor quality of contaminated water affecting the health of humans. Thus, it is an essential study to investigate factors affecting groundwater quality and its suitability for drinking uses. In this paper, the entropy theory, multivariate statistics, spatial autocorrelation index, and geostatistics are applied to characterize groundwater quality and its spatial variability in the Sylhet district of Bangladesh. A total of 91samples have been collected from wells (e.g., shallow, intermediate, and deep tube wells at 15-300-m depth) from the study area. The results show that NO3-, then SO42-, and As are the most contributed parameters influencing the groundwater quality according to the entropy theory. The principal component analysis (PCA) and correlation coefficient also confirm the results of the entropy theory. However, Na+ has the highest spatial autocorrelation and the most entropy, thus affecting the groundwater quality. Based on the entropy-weighted water quality index (EWQI) and groundwater quality index (GWQI) classifications, it is observed that 60.45 and 53.86% of water samples are classified as having an excellent to good qualities, while the remaining samples vary from medium to extremely poor quality domains for drinking purposes. Furthermore, the EWQI classification provides the more reasonable results than GWQIs due to its simplicity, accuracy, and ignoring of artificial weight. A Gaussian semivariogram model has been chosen to the best fit model, and groundwater quality indices have a weak spatial dependence, suggesting that both geogenic and anthropogenic factors play a pivotal role in spatial heterogeneity of groundwater quality oscillations.

Shallow groundwater quality assessment: use of the improved Nemerow pollution index, wavelet transform and neural networks

Shallow groundwater is generally of great interest to the community due to its easy availability. However, it is very sensitive to external stimulus. In this paper, shallow groundwater quality is assessed and classified with improved Nemerow pollution index, multi-layer perceptron artificial neural network (MLP-ANN) optimized with a back-propagation algorithm and wavelet neural network (WNN) methods in a coastal aquifer, Fujian Province, South China. The data used in three models were collected during the pre-monsoon over the period 2004–2011. The eight parameters, total dissolved solids, total hardness, chemical oxygen demand, chloride, sulphate, nitrate, nitrite and fluorides, were selected to characterize groundwater quality classification based on the National Quality Standard for Groundwater (GB/T 14848-93). The results of MLP-ANN and WNN are interpreted by mean absolute error, root mean square error and R2 (determination coefficient) criteria. The results obtained from three methods demonstrate that WNN has a higher accuracy compared with the other two methods. The study reveals that these methods are efficient tools for assessing groundwater quality.

Assessment of groundwater quality index for drinking purpose in the Durg district, Chhattisgarh using Geographical Information System (GIS) and Multi-Criteria Decision Analysis (MCDA) techniques

Present study is carried out to evaluate and characterize groundwater quality using Geographical Information System (GIS) and Multi-Criteria Decision Analysis (MCDA) Techniques. In order to ascertain the groundwater quality a detailed survey was carried-out and a total 88 numbers of groundwater samples were collected from different locations of the Durg district. Various physicochemical parameters of collected groundwater samples were analyzed for the periods of 5-years from 2007 to 2011 during premonsoon period. Six criteria viz. pH, calcium (Ca++), magnesium (Mg++), chloride (Cl–), nitrate (NO– 3) and fluoride (F–) were used for the determination of groundwater quality index. The analytical hierarchical process (AHP) used to determine the weight of various parameters and their classes for identifying the groundwater quality index. Present study is helpful for long-term planning and management of groundwater resources of the study area.

Identification and Apportionment of Pollution Sources to Groundwater Quality

Characterizing groundwater quality and apportionment of pollution sources to groundwater pollution is important for managing water resources effectively. Owing to rapid industrialization and population growth in Bengaluru city, the groundwater quality is getting deteriorated. Receptor modeling by Multi-Linear Regression of the Absolute Principal Component Scores (APCS-MLR) has been used to evaluate the source apportionment of groundwater pollution in order to recognize and quantify the pollution sources. Groundwater quality data measured for pre-monsoon and post-monsoon in the year 2014, comprising 14 physico-chemical parameters from 68 sites distributed across the study area, have been used. Principal component analysis identified four factors explaining 79.2 % of the total variance. Receptor modeling using APCS-MLR provided apportionment of different sources responsible for the groundwater quality along with percentage contribution of the recognized sources to each parameter. Results revealed that most of the variables were primarily affected by rock water interactions, seepage of sewage and industrial effluent. It was also found that few parameters gained significant contribution from the unidentified sources. Finally, the model performance was evaluated based on the ratio of estimated mean to measured mean (E/M). It was found that except for Fe with (E/M) ratio as high as 7.1, the model showed moderate strength with (E/M) values ranging from 0.51 to 2.83 of all the other parameters.

Groundwater Quality in the Vicinity of Aba-Eku Dumpsite, Ibadan, SW Nigeria: A Detailed Report

Groundwater contamination by landfill leachate is a recognized socio-economic and environmental problem in many countries. The Aba-Eku dumpsite was upgraded and the present study undertaken to characterize groundwater quality in the vicinity of the site to assess the effectiveness of the upgrades. Twenty three parameters were assessed in two groundwater wells (GW1 and GW2 located 600m from the site) over a twenty-month period using Inductively Coupled Plasma Spectroscopy and Ion Chromatography. Data were analyzed using t-test, ANOVA and correlation coefficients. Phosphates and nitrites were below detection limits. Suspended solids: [42.96±67.68 mg/l]; COD-[9.80±4.07mg/l]; and four metals [Pb: 0.047±0.029; Cu: 0.017±0.009; Ni: 0.012±0.011; Cr: 0.014±0.019 mg/l] were elevated in the up-gradient well GW1. However, only lead was significant (p<0.05). Fifteen parameters were elevated in GW2 down-gradient, of which nine including: pH: 8.15±0.11, dissolved solids: 241.39±62.89; magnesium: 28.25±17.52; chloride: 38.19±16.80; sulphate: 27.00±9.62 and cadmium: 0.070±0.045 mg/l were significant (p<0.05). Mean lead, GW1-0.047±0.029; GW2- 0.015±0.018; cadmium GW1-0.028±0.047; GW2-0.070±0.045 and iron GW1-0.82±0.61; GW2- 2.43±4.33 mg/l levels in both wells exceeded regulatory limits. Correlation results [GW1:TSSCOD; 0.713;p<0.01; GW2:TSS-COD:0.262] indicated that the turbid nature of GW1 reflected in higher levels of TSS appeared to be composed of organics and may have contributed to lead mobilization in this well. Zinc mobilization in both wells was strongly pH dependent [GW1: pH-Zn: -0.491;p<0.01; GW2:pH-Zn: -0.682;p<0.05]. Seasonal variations were less distinct. However, increased leachate influx into GW2 resulted in significantly elevated wet season levels of pH, nitrates, sulphates, chloride and TDS. There is urgent need for remediation in view of the health implications of these pollutants.Key words: Groundwater, Aba-Eku dumpsite, landfill leachate, Remediation.