Level Of Groundwater Contamination Research Articles

Geophysical Electrical Investigation of Groundwater Contamination Using Resistivity Method at a Dumpsite in Ibwa, Gwagwalada Area Council, Abuja, Nigeria

Ground water occurrence and distribution in a basement complex is localize and confined to weathered / fractured zone. Hence, exploration of groundwater in such terrain poses a great threat and challenge to the Ibwa community. This study was aimed at using vertical electrical sounding (VES) method to investigate the level of ground water contamination within the community of Ibwa village Gwagwalada area council. The result showed the presence of four geoelectric layers, top soil, Sandy clay, clayey sand and the basement. The resistivity values were obtained range from 20.1 Ωm to 149.0 Ωm at the first layers of most all the sounding points around the dumpsite. Other layers showed high resistivity values but not as that of high asthe control site, an indication that there are leachate plume from the dump through the process of percolation. The result is further back up with water analysis test which shows that all parameters measured falls within the World health organization standard for drinking water (WHO Threshold). The result showed that for the Well water sample is higher in acidity. It is clear therefore that there are more dissolved substances in the well water around the area as a result of leachate from the dumpsite.

The Result of Electrical Resistivity Investigation of Solid Waste Landfill Conducted at Nsukka Municipality Using Electrical Resistivity Measurments

Solid waste landfill management has been a significant issue for Nigerian urban areas and other developing countries across the globe.Similar to most other cities, Nsukka also generates waste on a daily basis, much of which is dumped in poorly designed and positioned dumping sites. The majority of the disposal sites are found on roadsides, at marketplaces, on farms, and in residential neighborhoods, among other places. The road infrastructure and groundwater are under danger, and the beauty of the impacted communities are not spared. Undoubtedly, the unchecked citation of boreholes as the source of potable water in the majority of our rural and urban communities—given that the government doesn't seem to be providing water to the people—has become a significant challenge. An investigation using electrical resistivity method was conducted around a solid waste dumpsite at Nsukka in Nsukka L.G.A of Enugu State, Nigeria with an aim to investigate the level of groundwater contamination and the objectives to determine the subsurface geoelectric layers, depth to water table, lithology delineation and map out the contamination zones. The scope of this study provides an overview of some of the approaches used to assess the aquifer vulnerability and aquifer potential using Vertical Electrical Sounding (Schlumberger array) and 2D resistivity imaging (Wenner array) in different locations around Nsukka municipality dumpsite. Both methods were used for this study in order to provide a geophysical database for exploration of the study area’s groundwater resources and also they are less expensive and less time consuming. VES has proved to be effective in solving groundwater problems in most places in Nigeria (Ezeh and Ugwu, 2010; Ugwu and Ezeh, 2012; Nzemeka et al. [1,2]. Electrical Sounding (VES) and 2D resistivity imaging were carried out with a digital read out resistivity meter (ABEM SAS 1000) to acquire data in the area and were interpreted using the Schlumberger automatic INTERPEX analysis software and the RES2DINV software respectively, which generates model curves using initial layer parameters and display the variations of electrical resistivities respectively. A total of eight (8) sounding and six (6) 2D resistivity imagings were carried out in the area. A contaminant leachate plume was delineated in 2D resistivity sections as low resistivity zones while the VES shows the depth of aquifer. In 2D pseudosections where bluish colours with low resistivities (less than 20.80\(\Omega\)m) with the depth ranging from 1.28m to 17.1m in the Line 1 and 2 are seen as contaminated zones. The rest of the lines are not contaminated because of their high resistivities (greater than 20.80\(\Omega\)m). The result of the electrical resistivity survey also showed 4 - 5 layers geo-electric sections and an AA and AK type sounding curves. The VES result shows that VES 1A, 1B, 2A and 2B which are carried out on line 1 & 2 of the wenner lines showed signs of contamination with low resistivity values less than 20.80\(\Omega\)m complementing the wenner results. The contamination has not yet got to where the aquifer is located on the lines. Since the depth to the aquifer ranges from 30.26m to 155.43m while maximum depth of contamination is 17.1m. It is believed that the leachate has not percolated down to the aquiferous zones as such aquifers are presumed to be free. As such, it is recommended that boreholes around the study area should not be less than 30m deep to avoid exploiting polluted water.

Mapping and assessment of groundwater pollution risks in the main aquifer of the Mostaganem plateau (Northwest Algeria): utilizing the novel vulnerability index and decision tree model.

Water plays a pivotal role in socio-economic development in Algeria. However, the overexploitations of groundwater resources, water scarcity, and the proliferation of pollution sources (including industrial and urban effluents, untreated landfills, and chemical fertilizers, etc.) have resulted in substantial groundwater contamination. Preserving water irrigation quality has thus become a primary priority, capturing the attention of both scientists and local authorities. The current study introduces an innovative method to mapping contamination risks, integrating vulnerability assessments, land use patterns (as a sources of pollution), and groundwater overexploitation (represented by the waterhole density) through the implementation of a decision tree model. The resulting risk map illustrates the probability of contamination occurrence in the substantial aquifer on the plateau of Mostaganem. An agricultural region characterized by the intensive nutrients and pesticides use, the significant presence of septic tanks, widespread illegal dumping, and a technical landfill not compliant with environmental standards. The critical situation in the region is exacerbated by excessive groundwater pumping surpassing the aquifer's natural replenishment capacity (with 115 boreholes and 6345 operational wells), especially in a semi-arid climate featuring limited water resources and frequent drought. Vulnerability was evaluated using the DRFTID method, a derivative of the DRASTIC model, considering parameters such as depth to groundwater, recharge, fracture density, slope, nature of the unsaturated zone, and the drainage density. All these parameters are combined with analyses of inter-parameter relationship effects. The results show a spatial distribution into three risk levels (low, medium, and high), with 31.5% designated as high risk, and 56% as medium risk. The validation of this mapping relies on the assessment of physicochemical analyses in samples collected between 2010 and 2020. The results indicate elevated groundwater contamination levels in samples. Chloride exceeded acceptable levels by 100%, nitrate by 71%, calcium by 50%, and sodium by 42%. These elevated concentrations impact electrical conductivity, resulting in highly mineralized water attributed to anthropogenic agricultural pollution and septic tank discharges. High-risk zones align with areas exhibiting elevated nitrate and chloride concentrations. This model, deemed satisfactory, significantly enhances the sustainable management of water resources and irrigated land across various areas. In the long term, it would be beneficial to refine "vulnerability and risk" models by integrating detailed data on land use, groundwater exploitation, and hydrogeological and hydrochemical characteristics. This approach could improve vulnerability accuracy and pollution risk maps, particularly through detailed local data availability. It is also crucial that public authorities support these initiatives by adapting them to local geographical and climatic specificities on a regional and national scale. Finally, these studies have the potential to foster sustainable development at different geographical levels.

Integrated assessment of pollution status of MSW sites: a case study of Uyo, Ikot Ekpene and Oron, Akwa Ibom State, southern Nigeria.

One of the main causes of contaminated groundwater in emerging nations is improper trash disposal in urban areas, which affects the level of groundwater contamination caused by contaminants of municipal solid waste (MSW) origin within the three local government headquarters in Akwa Ibom State, southeastern Nigeria. The main thrust of this research survey is to assess the level of groundwater contaminations and their consequences. The research used statistical data generated from the Electrical Resistivity Survey (ERS) in combination with hydrogeochemical investigations. Analysis of variance of resistivity between Uyo, Ikot Ekpene and Oron was carried out. The test result indicated significant difference in contamination among the three cities. This was followed by a t-test between each pair of dump and control sites in the three cities. The test results showed significant difference between each control and dumpsite. The results showed that leachate layer conductivity is always higher than that of the layer above it. All water samples from boreholes close to the dumpsites were identified by hydrogeochemical analysis to exhibit pH (3.70-4.15) lower than the permissible limit of the WHO; few water samples exhibit increased electrical conductivity (EC), cadmium and total dissolved solids (TDS). Similarly, the bacteriological analyses indicated a high level of microbial load due to the waste dump. Formations found in boreholes close to the dumpsite have litho-correlations which depict intercalations of comparatively impermeable and porous materials. The findings reveal that leachate (contaminate) travels slowly downward, allowing for physical, chemical and biological processes to filter out impurities before they get to the aquifer. It is recommended that no new water supply wells should be placed in areas of abnormally low resistivity and physicochemical and bacteriological parameters, until the reasons for these values are properly assessed.

Hydraulic containment of TCE contaminated groundwater using pulsed pump-and-treat: Performance evaluation and vapor intrusion risk assessment

Remedial actions for groundwater contamination such as containment, in-situ remediation, and pump-and-treat have been developed. This study investigates the hydraulic containment of Trichloroethylene (TCE) contaminated groundwater by using pulsed pump-and-treat technology. The hypothetical research site assumed the operation of pulsed pump-and-treat to manage groundwater contaminated with 0.1 mg/L of TCE. at the pump-and-treat facility. Numerical models, employing MODFLOW and MT3DMS for groundwater flow and contamination simulations, were used for case studies to evaluate the performance and risks of pump-and-treat operation strategies. Evaluation criteria included capture width, removal efficiency, and contaminant leakage. Health risks from TCE leakage were assessed using a vapor intrusion risk assessment tool in adjacent areas. In the facility-scale case study, the capture width of the pump-and-treat was controlled by pumping/injection well operations, including schedules and rates. Pumping/injection well configurations impacted facility efficiencies. Pulsed operation led to TCE leakage downstream. Site-scale case studies simulated contaminant transport through pump-and-treat considering various operation stages (continuous; pulsed), as well as various reactions of TCE in subsurface environment (non-reactive; sorption; sorption and biodegradation). Assuming non-reactive tracer, TCE in groundwater was effectively blocked during continuous operation stage but released downstream in the following pulsed operation stage. Considering chemical reactions, the influences of the pump-and-treat operation followed similar trends of the non-reactive tracer but occurred at delayed times. Groundwater contamination levels were reduced through biodegradation. Cancer and non-cancer risks could occur at points of exposure (POEs) where the contamination levels approached or fell below TCE groundwater standards.

Vulnerability and Risk of Contamination of the Varaždin Aquifer System, NW Croatia

This paper presents the first study that assesses the vulnerability and risk of contamination of groundwater in the Varaždin aquifer system. The alluvial aquifer system is mostly unconfined with favorable hydrogeological features. Out of three wellfields, two still operate at full capacity, while the Varaždin wellfield, once the major source of drinking water, has been abandoned due to high concentrations of nitrates in the groundwater. Index-based methods are employed to assess groundwater vulnerability—two DRASTIC-based methods, standard and P-DRASTIC; two SINTACS-based methods, with normal and severe weighting strings; and the GOD method. Hazard is evaluated according to recommendations from the EU COST 620 action, while the risk intensity of the resource is calculated using the results of vulnerability and hazard assessments. The results reveal that for all vulnerability models, the resulting maps have a similar distribution pattern of vulnerability classes, with the high vulnerability class prevailing. However, notwithstanding the generally high groundwater vulnerability, a moderate resource contamination risk prevails as a consequence of a dominantly low hazard index. The validation of the groundwater vulnerability models demonstrates a weak correlation between the vulnerability indices and mean nitrate concentrations in groundwater. Conversely, a significantly higher correlation coefficient (0.58) is obtained when the groundwater vulnerability index is replaced by the resource risk intensity index, indicating that the results of resource risk intensity assessments are superior to groundwater vulnerability results in predicting the level of groundwater contamination.

Analysis and evaluation of groundwater pollution in Shouguang, China

AbstractGroundwater is an essential nonrenewable resource for agricultural activities. In this study, groundwater samples were collected from the Shouguang area, and the level of groundwater contamination was investigated by measuring the NO3−, SO42−, F−, Cl−, Ca2+, Mg2+, total dissolved solids (TDS) and chemical oxygen demand (COD). Exploratory data analysis was employed initially to study the hydrochemical characteristics and the sources of pollutants. Finally, the groundwater quality was measured using principal component analysis, entropy weight and complex correlation coefficient methods. As a common observation, the groundwater in the Shouguang area is slightly alkaline, so Ca2+, Mg2+ and NO3− acted as predominant pollutants. These contaminants originated from the excessive use of chemical fertilizers and large‐scale sewage irrigation. Second, perennial overexploitation of groundwater in Shouguang led to the generation of funnels and led to seawater intrusion. As a result, Cl− and TDS in the water samples collected from the north Shouguang area exceeded the regulatory guideline value, which indicates the risk of land salinization. However, the measured concentrations of SO42−, F− and COD were within the normal range. This confirms the minimal contribution of industries to groundwater pollution. East of the Ni River the groundwater is severely polluted, and the detected concentrations of pollutants are far beyond the standard limit and pose a potential risk to human health. Therefore, protection and treatment are urgently needed.

Understanding the phenomenon of saltwater intrusion sourced from desalination plants at coastal aquifers.

Members of the Gulf Cooperation Council countries Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates rely on desalination to produce water for domestic use. Desalination produces brine that may intrude into the aquifers to pollute the fresh groundwater because of the concentration gradient and groundwater pumping. Modeling the trends of saltwater intrusion needs theoretical understanding and thorough logical experimentation. The objective of this exercise was to understand the phenomenon of saltwater intrusion using an existing set of data analyzed with the convective-diffusion equation and the two-region mobile-immobile solution model. The objective was achieved by optimizing non-measurable solute transport parameters from an existing set of data generated from a series of logical miscible displacements of potassium bromide through sepiolite minerals and curve-fitting simulations. Assumptions included that solute displacements through sepiolite porous media and the related simulations represented the phenomenon of saltwater intrusion under non-equilibrium conditions of porous media mimicking the aquifers. Miscible displacements of potassium bromide were observed from a column of 2.0-2.8mm aggregates of sepiolite over 4 ranges of concentration and at 11 displacement speeds under saturated vertical flow deionized water and vice versa. Breakthrough curves of both bromide and potassium ions were analyzed by a curve-fitting technique to optimize transport parameters assuming solute movement was governed (i) by the convective-diffusion equation and (ii) the two-region mobile-immobile solution model. Column Peclet numbers from the two analyses were identical for potassium ions but those for bromide ions were c. 60% greater from the two-region model than from the convective-diffusion equation. For the two-region model, dispersion coefficients were well defined and remained unchanged from the convective-diffusion equation for potassium ions but decreased for bromide ions. Retardation factors for bromide ions were approximately the same, but those for potassium ions, though > 1, were poorly defined. In order to design mitigation strategies for avoiding groundwater contamination, this study's findings may help model groundwater pollution caused by the activities of desalination of seawater, which produces concentrated liquid that intrudes into the coastal aquifer through miscible displacement. However, robust saltwater intrusion models may be considered in future studies to confirm the results of the approach presented in this exercise. Field data on the groundwater contamination levels may be collected to compare with simulated trends drawn from the saltwater intrusion models and the curve-fitting technique used in this work. A comparison of the output from the two types of models may help determine the right option to understand the phenomena of saltwater intrusion into coastal aquifers of various characteristics.

Groundwater Vulnerability Assessment and Protection Strategy in the Coastal Area of China: A GIS-Based DRASTIC Model Approach

Groundwater vulnerability reflects the risk level of groundwater contamination and its self-repairing ability, as well as its sustainability for use. Therefore, it provides significant scientific support for implementing measures to prevent groundwater contamination, especially in coastal areas. In this study, considering the lithology of vadose in valley plains and the extent of karst subsidence areas, a GIS-based DRASTIC model was employed to assess groundwater vulnerability in Tangshan City, a coastal area in China. The assessment results were presented and mapped using GIS, based on a comprehensive evaluation of seven parameters, including “Depth of groundwater, Vertical net recharge, Aquifer thickness, Soil media, Topography, Impact of vadose zone, and Hydraulic conductivity”. The identified groundwater vulnerability zones included the highest, higher, moderate, low vulnerability those four zones, which accounted for 4%, 53%, 25%, and 18%, respectively. In addition, according to the results of field investigation, the karst subsidence area and the mined-out coastal area were directly classified as the highest vulnerable areas and covered 1.463 km2; more attention is required here in subsequent groundwater protection processes and strategies. Finally, the groundwater pollution index was used to validate the groundwater vulnerability distribution results, and these two were in high agreement, with an R2 coefficient of 0.961. The study is crucial for the rational utilization and protection of water resources in Tangshan City.

Forecasting of Groundwater Quality by Using Deep Learning Time Series Techniques in an Arid Region

Groundwater is regarded as the primary source of agricultural and drinking water in semi-arid and arid regions. However, toxic substances released from sources such as landfills, industries, insecticides, and fertilizers from the previous year exhibited extreme levels of groundwater contamination. As a result, it is crucial to assess the quality of the groundwater for agricultural and drinking activities, both its current use and its potential to become a reliable water supply for individuals. The quality of the groundwater is critical in Egypt’s Sohag region because it serves as a major alternative source of agricultural activities and residential supplies, in addition to providing drinking water, and residents there frequently have issues with the water’s suitability for human consumption. This research assesses groundwater quality and future forecasting using Deep Learning Time Series Techniques (DLTS) and long short-term memory (LSTM) in Sohag, Egypt. Ten groundwater quality parameters (pH, Sulfate, Nitrates, Magnesium, Chlorides, Iron, Total Coliform, TDS, Total Hardness, and Turbidity) at the seven pumping wells were used in the analysis to create the water quality index (WQI). The model was tested and trained using actual data over nine years from seven wells in Sohag, Egypt. The high quantities of iron and magnesium in the groundwater samples produced a high WQI. The proposed forecasting model provided good performances in terms of average mean-square error (MSE) and average root-mean-square error (RMSE) with values of 1.6091 × 10−7 and 4.0114 × 10−4, respectively. The WQI model’s findings demonstrated that it could assist managers and policymakers in better managing groundwater resources in arid areas.

ISOLATION OF MULTI DRUG RESISTANT BACTERIA FROM BORE WATER SAMPLES IN AND AROUND VISAKHAPATNAM

Objective: The aim of the present study was to determine the levels of groundwater contamination by isolating total coliforms, fecal coliforms, and bacterial pathogens.
 Methods: A total of 32 water samples, comprising 5 samples from each GVMC urban area zone, Visakhapatnam were randomly collected from different areas. Evaluation of Total and fecal coliform counts was done by using multiple-tube fermentation technique and were reported as the most probable number (MPN) of organisms present per 100 ml of sample.
 Results: The samples collected from the zones Yendada (zone I), Marripalem (zone IV), Chinna musidiwada (zone VI) showed the highest total and fecal coliform counts (MPN>180). Nearly 30 samples (94%) yielded bacterial isolates. Among the isolates Pseudomonas spp. showed highest susceptibility to cefepime and imipenem antibiotics. All the microorganisms isolated were multidrug resistant with a multidrug antibiotic resistant index more than 0.2.
 Conclusion: These multidrug-resistant (MDR) organisms are considered as a major threat to the public health and should receive more attention.

Assessment of Groundwater Decontamination Processes around a Dismantled Septic Tank Using GIS and Statistical Analysis

Septic tanks without proper construction and insulation entail a significant risk to the environment. In this study, the environmental impacts of a permeably designed septic tank on shallow groundwater contamination are investigated, and changes in water quality in the period after its elimination in 2014 are assessed. For the purpose of evaluating the pollution level of the site, 10 monitoring wells were installed around the septic tank in 2012 and long-term monitoring was carried out. Analytical measurements revealed a significant level of groundwater contamination in the operational period of the septic tank. Extremely high concentrations of NH4+ (>90 mg/L) were observed in the closest monitoring wells, and in most of the wells, concentrations exceeded the relevant contamination limit. δD and δ18O isotopic ratios of monitoring wells within 1 m from the septic tank indicate continuous recharge of sewage water originating from deeper aquifers. The groundwater dome resulting from the wastewater discharge exceeded 1.1 m, within a distance of 25 m. Statistical analyses also revealed significant changes in water quality depending on the monitoring well location from the septic tank. In the period after the septic tank elimination, considerable changes have been detected. Following the cessation of the wastewater discharge, the groundwater dome around the septic tank disappeared; therefore, differences in groundwater levels have decreased from more than 1 m to a few cm. Significant positive changes were detected in the water quality parameters investigated after the dismantling of the septic tank. Five years after the cessation of the pollutant supply, concentrations still exceeded the contamination limit in most of the monitoring wells, indicating slow decontamination processes with a permanently high level of pollution.

Analysis of Groundwater Pollution Levels in the Alluvial Plains of Semarang City

Water is the source of life for all living things on Earth. Indonesian people make groundwater the main source of water, including the people in Semarang City. The city of Semarang, which is the capital city of Central Java province, with the development of industry, trade and tourism growing rapidly, has forced groundwater exploitation on a large scale. As a result, disasters such as drought, the phenomenon of seawater intrusion and groundwater contamination have started to occur in the city of Semarang, especially in the alluvial plains area. This study aims to determine the level of groundwater contamination in the study area. In this study, 30 groundwater samples were taken to test the chemical content of groundwater. The methods used were the geospatial analysis and the Pollution Groundwater Index (PGI). The geospatial in Geographic Information System/GIS method aims to determine the distribution of groundwater quality in the study area. The PIG method aims to determine the level of groundwater contamination. PGI results show that there is 1 sample belonging to high pollution and 1 other sample belonging to groundwater with very high pollution. Geospatially, it shows that the distribution of groundwater contamination is in the western and central parts of the study area. This is also supported by geospatial analysis for the physicochemical conditions of groundwater which includes parameters of pH, EC, TDS and Hardness. From this research, it is known that groundwater in Semarang City is starting to experience pollution. So there is a need for efforts to restore groundwater conditions and start reducing the use of groundwater by utilizing surface water.Introduction

Combining the classic vulnerability index and affinity propagation clustering algorithm to assess the intrinsic aquifer vulnerability of coastal aquifers on an integrated scale

In the northern plains of Laizhou City, groundwater quality suffers dual threats from anthropogenic activities: seawater intrusion caused by overextraction of fresh groundwater, and vertical infiltration of agricultural pollutants. Groundwater management requires a comprehensive analysis of both horizontal and vertical pollution in coastal aquifers. In this paper, Intrinsic Aquifer Vulnerability (IAV) was assessed on an integrated scale using two classic IAV models (DRASTIC and GALDIT) separately based on a GIS database. Hydrogeological parameters from two classic IAV models were clustered using affinity propagation (AP) clustering algorithm, and silhouette coefficients were used to determine the optimal classification result.In our application, the objects of the AP algorithm are 3320 units divided from the whole study area with 500 m*500 m precision. A comparison of all four outputs in AP-DRASTIC shows that the clustering results of the 4-classification yielded the best silhouette coefficient of 0.406 out of all four. Cluster 4, which comprises 21% of the area, had relatively low level of groundwater contamination, despite its high level of vulnerability as indicated by the classic DRASTIC index. In the second level of vulnerability Cluster 3, 53.8% of all water samples were found to be contaminated, indicating a greater level of nitrate contamination. With respect to AP-GALDIT, the silhouette coefficient for result 7-classification reaches the highest value of 0.343. There was a high level of vulnerability identified in Clusters 2, 4 and 5 (34.7% of the study area) relating to the classic GALDIT index. The concentration of chloride in all water samples obtained in these areas was extremely high. Groundwater management should be addressed by AP-DRASTIC results on anthropogenic activity/contamination control, and by AP-GALDIT results on groundwater extraction limitation. Overall, this method allows for the evaluation of IAV in other coastal areas on an integrated scale, facilitating the development of groundwater management strategies based on a better understanding of the aquifer's essential characteristics.

Hydrogeochemistry and quality evaluation of groundwater and its impact on human health in North Tripura, India.

Groundwater contamination becomes an alarming threat to the provision of ecosystem services and natural resources. A very high level of groundwater contamination has been observed in the northeastern states particularly in North Tripura district. Therefore, the present study considered the region as a case study to evaluate the hydrogeochemical facies, heavy metal pollution and irrigation indices, and their impact on human health. For the investigation, we have collected a total of 35 groundwater samples from North Tripura district. Hydrogeochemical facies through Piper plot reflect Ca2+-Mg2+-HCO3- and Na+-HCO3- as dominant water types. Gibbs plot identifies the dominance of rock-water interaction process in groundwater hydrochemistry. Geochemical plots indicate the dominance of silicate weathering, ion exchange and carbonate dissolution processes in groundwater mineralisation. The order of trace metal contaminations follows Fe > As > Zn > Mn > Cu > Pb. Results of heavy metal indices suggest above 80% samples are at high risk due to high Fe contamination. The risk of the heavy metal indices is associated with rising elevation in southern part of North Tripura. Findings of health risk assessment study imply that children face much carcinogenic and non-carcinogenic risks than adults because of unsafe levels of Fe and As. Multivariate statistical tools are applied to unravel interrelationships among all ions and trace metals as well as probable hydrogeochemical processes in groundwater. Results of Wilcox and USSL plots suggest 77% samples meet irrigation suitability criteria. Besides, the analysis suggests a better insight to identify hydrogeochemical processes controlling groundwater chemistry and the suitability of groundwater for irrigation and drinking purposes. The study also suggests treatment and sustainable management of groundwater resources is compulsory to reduce trace metal contaminations before public use.

Identification of Water Contamination Sources Using Hydrochemical and Isotopic Studies—The Kozłowa Góra Reservoir Catchment Area (Southern Poland)

The application of combined research methods, such as hydrochemical and isotopic analyses, facilitates understanding of the origin of water constituents and migration of contaminants in the aquatic environment. The presented study attempts to identify contamination sources affecting water quality within the Kozłowa Góra reservoir catchment area (southern Poland). A total of 100 water samples were collected from surface water (the Brynica river, streams, and the reservoir) and groundwater (a Quarternary aquifer) in four time periods. During fieldwork, the physicochemical parameters were measured (temperature, pH, electrical conductivity, redox potential, and dissolved oxygen). The chemical analysis included the determination of major ions (HCO3−, SO42−, Cl−, Ca2+, Mg2+, Na+, and K+), nutrients (NO3−, NO2−, NH4+, and PO43−), and total organic carbon. The study was complemented by isotopic analysis of sulphur and oxygen in sulphate, which enabled a more precise identification of stressors affecting water quality in different parts of the catchment area. Chemical and isotopic results (δ34S = 4.38–13.99‰; δ18O 3.59–13.30‰) revealed that wastewater discharges and agricultural activities have a significant influence on the chemistry of the Brynica River and other streams. At some sampling points, a lower quality of water was manifested by elevated concentrations of NO3− (up to 22.6 mg/L) and several other ions (e.g., up to 114 mg/L for Cl−, up to 51.52 mg/L for NH4+, and 12.5 mg/L for PO43−). The quality of groundwater was deteriorated mainly by infiltration of sewage from leaky septic tanks. The level of groundwater contamination varied depending on the location, as higher concentrations of major ions and values of electrical conductivity were observed in residential areas. The Brynica river, streams, and groundwater recharge the drinking water reservoir, and thus its quality depends on these sources. A dilution of water and the presence of biochemical processes led to a reduction of contaminant concentrations in the Kozłowa Góra reservoir (down to 3.5 mg/L for NO3−, 32 mg/L for Cl−, 0.21 mg/L for NH4+, and <0.05 mg/L for PO43−) compared to water in the river and streams supplying the reservoir. The study revealed the role of wastewater discharge and agricultural activities in the evolution of surface water chemistry. The results will be used in further research on the origin and migration of other substances in water, including microcontaminants.

DETERMINATION OF CONTAMINATION DISTANCE FOR BOREHOLES IN OKIGWE ZONE, IMO STATE NIGERIA

Groundwater contaminants in Okigwe zone in Imo state made up of six local government areas were investigated. Four (4) groundwater samples were collected from each local government area. This amounted to twentyfour groundwater samples. These samples were collected randomly from sites close to septic tanks and to avoid contamination from tanks, the samples were collected at the well head, before water enters into storage tanks. The samples were stored in a sterilized 250 ml bottles and then taken to the laboratory for analysis. The chemical parameters were determined using a HA-CH 44600-00 and using standard methods as contained in Chessbourgh (2014). These samples were refrigerated and analyzed within 24 h. All plastics and glass wares utilized were pre-washed with detergent water solution, rinsed with tap water and soaked for 48 h in 50% HNO3 then rinsed thoroughly with distilled- deionized water. These results were used to ascertain the levels of groundwater contamination in Okigwe zone. An equation was generated from the chemical parameters using SPSS and E-view softwares to estimate the minimum allowable distance for locating borehole from sources of contamination in Okigwe zone in Imo state Nigeria. The minimum allowable distance calculated for groundwater from sources of contamination (septic tanks) is 15.81meters.

The Use of the Contamination Index and the LWPI Index to Assess the Quality of Groundwater in the Area of a Municipal Waste Landfill.

Environmental degradation caused by the migration of pollutants from landfills is one of the biggest problems for urban areas. Systematic monitoring of groundwater in the vicinity of waste dumps allows for an assessment of the degree of risk to the soil and water environment. In this paper, spatiotemporal variation of groundwater pollution near a municipal landfill in Sosnowiec (southern Poland) was investigated. For this purpose, the monitoring results of five physicochemical indicators from 2014–2019 were used. This study presents an example of the application of the Landfill Water Pollution Index (LWPI) and the Cd Contamination Index. The obtained results indicated that the tested waters were negatively influenced by municipal landfills, especially in the southern part (piezometers P8 and P10). The values of the Contamination Index even reached a value equal of about 1400, while the values of the LWPI index reached 305. Significantly lower values of both indicators were obtained using the results of monitoring studies for other piezometers located upstream from the landfill but belonging to the observation network of a neighboring facility. The indices used permit a determination of the level of groundwater contamination from the described landfill and can be used in similar research areas.

Vulnerability Assessment of Groundwater Contamination from an Open dumpsite: Labete Dumpsite as a Case study

The assessment of leachate impact on groundwater is very crucial to human health and its environment. This research work aimed at assessing Labete dumpsite and its effects on groundwater integrity in the vicinity of the dumpsite. Soil samples were collected for leachate analysis at a depth of 0.5m from the earth’s surface within the proximity of the dumpsite. Four different groundwater samples (GW1-GW4) were collected at radial distances from the dumpsite. Collected water samples were analyzed to examine their Cr, Fe, Cd, Pb, Zn, and Cu ions content. Physicochemical and bacteriological analysis were also considered and measured against NSDWQ and WHO standards for drinking water. The results showed that the level of groundwater contamination is directly proportional to the depth of the water table (collection) and the distance of the dumpsite from the shallow wells. GW1 and GW2 groundwater samples were not fit for consumption unless adequately treated.

Assessment of heavy metal pollution in groundwater with respect to distance from ash pond by using heavy metal evaluation index

In order to assess the quality of groundwater near ash pond of Parichha Thermal Power Plant (Jhansi), heavy metal evaluation index (HEI)was calculated. An unlined ash pond is being used for a long time to dispose fly ash generated by thermal power plant. To assess the level of groundwater contamination due to ash slurry disposal, both groundwater and ash slurry samples were collected and analysed in terms of their chemical concentration. In the present study, it was observed that significant amount of trace elements can leach out from ash slurry and may contaminate groundwater due to downward percolation through soil strata in an unlined ash pond. Obtained results revealed the range of heavy metals concentration in groundwater as [Ni (0.02–0.07 mg/l), Pb (0.14–0.41 mg/l), Fe (0.20–7.21 mg/l), Mn (0.01–0.14 mg/l), Cr (0.03–0.05 mg/l) and Al (0.05–0.26 mg /l)]. HEI showed a heavy load of metal pollution within the range of 5 km from the ash pond while moderate pollution within the range of 7 km and very low at a distance of 15 km.