Analysis Of Groundwater Samples Research Articles

Integration of GIS and Water-Quality Index for Preliminary Assessment of Groundwater Suitability for Human Consumption and Irrigation in Semi-Arid Region

The Setifian high-plains region, Northeast of Algeria, grapples with challenges in water resource management. As the water demand intensifies across a diverse range of sectors, assessing groundwater quality becomes indispensable. This article responds to the critical need for a thorough assessment of groundwater quality in the Wadi Boussellam sub-watershed. Employing a GIS-based method, we evaluate groundwater geochemistry by estimating the Water Quality Index (WQI), offering a comprehensive overview of water consumption. The analysis of groundwater samples reveals distinct facies, including calcic bicarbonate, calcic chloride, calcic sulfate, and magnesium sulfate, contributing to an enhanced understanding of the hydrochemical composition in the Setif region. Hydrochemical indices, specifically the WQI, Sodium Adsorption Ratio (SAR), and Na% are applied to assess groundwater suitability for various applications. The results indicate that most crops are generally suitable for irrigation, though they advise exercising caution with regard to human consumption. This study underscores the significance of regular monitoring to avert groundwater contamination and ensure sustainable use in the Setif region, providing insights that emphasize the ongoing necessity for efforts in water resource management and the preservation of this vital resource’s quality.

Evolution of groundwater hydrochemical characteristics and formation mechanism during groundwater recharge: A case study in the Hutuo River alluvial–pluvial fan, North China Plain

A pilot project for groundwater recharge from rivers is currently being carried out in North China Plain. To investigate the influence of river recharge on groundwater hydrochemical characteristics, dynamic monitoring and analysis of groundwater samples were conducted at a typical recharge site in the Hutuo River alluvial-pluvial fan in the North China Plain from 2019 to 2021. Hydrochemical, isotopic, and multivariate statistical analyses were used to systematically reveal the spatiotemporal variation of groundwater chemistry and its driving factors during groundwater recharge process. The results showed that the groundwater hydrochemical types and characteristics in different recharge areas and recharge periods exhibited obvious spatiotemporal differences. The groundwater type varied from HCO3·SO4-Na·Mg to HCO3·SO4-Ca·Mg in an upstream ecological area, while the groundwater type changed from SO4·HCO3-Mg·Ca to HCO3·SO4-Ca·Mg in the downstream impacted by reclaimed water. Changes in the contents of Ca2+, Mg2+ and HCO3− were mostly controlled by the water–rock interactions and mixing-dilution of recharge water, while the increases in Na+, NO3−, Cl−, SO42− and NO3− contents were mainly due to the infiltration of reclaimed water. Nitrogen and oxygen isotope (δ15N and δ18O) tests and the Bayesian isotope mixing model results further demonstrated that nitrate pollution mainly originated from anthropogenic sources, and the major contribution came from manure and sewage, with an average proportion of 64.6 %. Principal component analysis indicated that water–rock interactions, river-groundwater mixing and redox environment alternation were dominant factors controlling groundwater chemical evolution in groundwater recharge process.

Geophysical, hydrogeological and laboratory assessment of groundwater quality and its health implication in some urban communities in cross river state

The electrical resistivity technique which involved the Schlumberger depth sounding method, electrical resistivity tomography and geochemical analyses of water samples collected from boreholes were used to investigate the quality of groundwater in some urban communities in Cross River State, also the health implication of the said groundwater was also investigated. Forty nine electrical resistivity data were collected, modeled, and interpreted after calibration with lithologic logs. Ten electrical resistivity tomography data was were also collected, modeled and interpreted. Forty nine borehole water samples were collected and analyzed to determine anion, cation concentrations and some physical and chemical parameters, such as water colour, temperature, total dissolved solids, and electrical conductivity. The results show that the lithostratigraphy of the study area is composed of sands, sandstones (fractured, consolidated and loosed), siltstones, shales (compacted and fractured) of the Asu River Group, Eze-Aku Formation which comprises the aquifer units, and the Nkporo Shale Formation. The aquifer conduits are known to be rich in silicate minerals, and the groundwater samples in some locations show a significant amount of Ca2+, Mg2+, and Na+. These cations balanced the consumption of H+ during the hydrolytic alteration of silicate minerals. The geochemical analysis of groundwater samples revealed dominant calcium–magnesium–carbonate– bicarbonate water faces. The groundwater quality was observed to be influenced by the interaction of some geologic processes but was classified to be good to excellent, indicating its suitability for domestic and irrigation purposes.

Nontargeted Screening of Contaminants of Emerging Concern in the Glen Valley Wastewater Treatment Plant, Botswana.

There is growing concern about the prevalence and impact of contaminants of emerging concern (CECs). The environmental monitoring of CECs has, however, been limited in low- and middle-income countries due to the lack of advanced analytical instrumentation locally. In the present study we employed a nontargeted and suspect screening workflow via liquid chromatography coupled with high-resolution mass spectrometry (HRMS) to identify known and unknown pollutants in the Glen Valley wastewater treatment plant, Botswana, complemented by analysis of groundwater samples. The present study represents the first HRMS analysis of CECs in water samples obtained in Botswana. Suspect screening of 5942 compounds qualitatively identified 28 compounds, including 26 pharmaceuticals and two illicit drugs (2-ethylmethcathinone and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol). Nontargeted analysis tentatively identified the presence of 34 more compounds including (5ξ)-12,13-dihydroxypodocarpa-8,11,13-trien-7-one, 12-aminododecanoic acid, atenolol acid, brilliant blue, cyclo leucylprolyl, decanophenone, DL-carnitine, N,N'-dicyclohexylurea, N4-acetylsulfamethoxazole, NP-003672, and 24 polyethylene glycol polymers. The highest number of detections were in influent wastewater (26 CECs) followed by effluent wastewater (10 CECs) and, lastly, groundwater (4 CECs). Seventeen CECs detected in the influent water were not detected in the effluent waters, suggesting reduced emissions due to wastewater treatment. Two antiretroviral compounds (abacavir and tenofovir) were detected in the influent and effluent sources. This suggests that wastewater treatment plants are a major pathway of chemical pollution to the environment in Botswana and will help inform prioritization efforts for monitoring and remediation that is protective of these key ecosystems. Environ Toxicol Chem 2024;43:52-61. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

ENGINEERING AND GEOLOGICAL STUDIES OF THE TENGIZ DEPOSIT

In this article, a study of geological and ecological loads on the geological environment at the Tengizfield, located in the Zhyloy district of Atyrau region of the Republic of Kazakhtan, is carried out. Soil tests by dynamic sounding (STDS) were performed on all drilling wells for sandy soils. In the process of performing engineering and geological exploration, static sounding of soils was performed at the projected sites of GDP-1 (gas distribution plant) and Torch, with the measurement of hydrostatic pore pressure. Physical and mechanical properties of soils, chemical properties of soils and chemical properties of groundwater were determined during laboratory studies. In the studied territory, the soils composing the engineering-geological section to a depth of up to 25 m are saline with an average degree of salinity. All lithological-facies groups of soils also contain a significant amount of carbonates and gypsum in their composition. For loamy silt (IGE-1b), according to the combination of physico-chemical and mechanical characteristics (fluid consistency, high degree of salinity, high degree of compressibility and low strength, the possibility of manifestation of thixotropic properties under dynamic influences), this soil belongs to the category of weak water-saturated clay soils. Weak soil (IGE-1b) is observed at a shallow depth in some areas. The available geotechnical data is not enough to accommodate areas of weak soils. At the same time, heavy sandy loam (IGE1a) and light sandy clay (IGE-8) have swelling properties of a weak degree. Chemical analysis of groundwater samples taken within the studied territories showed a high degree of mineralization, groundwater belongs to the brackish group, a subgroup of strongly brackish waters. Dangerous geological processes that could negatively affect the construction conditions are characterized by the processes of secondary salinization of soils.

Subsurface groundwater aquifer mapping and quality characterization in Matiari district, Sindh, Pakistan.

Groundwater, is an alternative resource, is used as a supplement for irrigation as well as drinking purposes in Pakistan. This paper aims to determine the quantum and quality of groundwater in Matiari district of Sindh, Pakistan, through Electrical Resistivity Survey (ERS). The ERS was conducted at 52 location points using the ABEM Terrameter SAS 4000. The quantity of good quality groundwater has also been evaluated with ArcGIS interpolation techniques, i.e., the maximum percentage of fresh groundwater is 34% the marginal fresh groundwater 43% at the depth of with few patches of saline groundwater aquifers. Moreover, at 50-m depth, the percentage of fresh groundwater reduces to 21% and the marginal has increased to 48%. However, groundwater below the depth from 50 to 100m was found only 8% fresh groundwater, 29% marginal, 49% salt water, and 14% high salt water. Analysis of groundwater samples for quality showed a good agreement with the quality obtained from VES results. In addition, a socio-economic survey of 55 tube well owners were conducted through interviews related to groundwater suitability and usage. According to the survey, about 62% of respondents are using good quality groundwater; however, 36% consuming the marginal and the remaining 2% are utilizing the hazardous quality of groundwater. The consumer satisfaction survey showed most farmers (89%) were satisfied with the groundwater usage, while 11% were unsatisfied due to poor-quality groundwater. The crop productivity could be enhanced through awareness and conjunctive use of marginal quality groundwater with the canal water.

Investigation the Origins of Groundwater Salinity in Baghdad City by Using Environmental Isotopes and Hydrochemical Techniques

The hydrochemical and isotopic techniques have become one of the most popular and successful methods for determining the hydrogeochemical features of groundwater in recent years. A total of 15 samples were collected during wet (March, 2021) and dry (August, 2021) seasons. An approach with major elements (Cl-, Na+, Mg2+, Ca2+, and SO4 2=) and multi-isotope (2H, 18O) are used in this study to solve the geochemical variation of salinity in groundwater in Baghdad. The results of the analysis of groundwater samples in the study area showed that the major cations were Ca2+ and Na+, while the major anion was SO4, Cl, and HCO3. The Ca-SO4 and Ca-Na-Cl-SO4. hydrochemical facies are the dominant hydrochemical facies of groundwater on the Al-Karakh and Al-Russafa sides, respectively. Ca-HCO3 was found to be the dominant hydrochemical facies of the Tigris River. Human activities and geochemical processes may have caused differences in hydrochemical Facies. According to isotope analysis, the study area has multiple sources of salinity. This can be attributed to the effects of natural dissolution of the salt compounds, mixing with sewage, and industrial water sink. The results and data from this work can be used to research groundwater recharge and interaction, as well as to protect groundwater quality.

Assessment of seawater ingress in the coastal aquifers of south Andaman Island, India

Seawater ingress is a widespread environmental issue posing threat to the fresh groundwater reserves of the coastal aquifers of Andaman and Nicobar Islands (ANI) particularly after the great Indian Ocean Tsunami 2004, and the comprehensive investigations of seawater ingress in this region are relatively uncommon. In this context, the spatial distribution and vertical movement of seawater ingress in the coastal and catchment areas were mapped using geo-spatial techniques and the extensive geoelectrical resistivity surveys (96 vertical electric soundings (VES) and profiling) along and across the identified and affected coastlines. The geoelectrical surveys unravels very low resistivity formations (≤10 Ω m) at varying depths interpreted as the lateral and vertical intrusion of seawater. The hydro-chemical and other physical analyses of groundwater samples reveal critical concentrations of the different major elements and other physical parameters like TDS, pH as well the EC above its permissible limit for drinking water standards. The integrated approach allows to delineate the site specific hydrogeological setting including the saline/fresh aquifer geometry (transition zone) and stratigraphic−geomorphological reconstruction of coastal aquifers. Further, various assessment parameters including very low formation resistivity, surface manifestation of salt tolerant plants, high chloride concentration, low formation factor and high ionic strength were employed to infer the various levels of contamination. The present study show that impact of seawater intrusion is intense in sedimentary formations than Ophiolite suite and needs site specific mitigation measure to prevent further deterioration of aquifer health.

Seasonal analysis of groundwater samples to identify water quality index and comparative statistical analysis of Hunsur Taluk, Mysuru, Karnataka, India

Groundwater quality assessment is critical for maintaining freshwater sources in semi-arid and dry environments, which is critical for long-term development. Water quality control authorities can regulate the use of water for agriculture or drinking implementations based on groundwater quality in various areas, as nearly 85% of India's population is reliant on groundwater for domestic and irrigation needs, particularly as a source of drinking in rural areas. From Hunsur taluk, Mysore district, Karnataka, India, this study explores and identifies potential places for pumping groundwater for drinking and irrigation. An analysis of groundwater quality was conducted by analyzing the Water Quality Index (WQI) determined from 30 wells during two seasons of the year 2019, namely Pre-Monsoon and Post-Monsoon. The identification of the quality of water resources for irrigation and drinking purposes can be determined with the help of the WQI. It’s extremely useful for classifying water quality considering the standard-based classification of water as excellent, good, poor, very poor, or unsuitable for drinking. By using the Weighted Arithmetic Index method calculated using the groundwater samples collected data for the study, reported ‘excellent water’ ranges between 80 and 83.33 and ‘good water’ between 20 and 16.67, and never found ‘poor water.’ The IWQ index for the study area has been reported to be in the average range of 17.35–65.64. This paper highlights the physico-chemical parameters assess water quality in comparison with climatology.

Health risk assessment from exposure to dissolved trace element concentration in drinking groundwater resources of Central Ganga Alluvial Plain: a case study of Lucknow region

ABSTRACT This study explores ‘Indicator Kriging’ approach for assessment of health risk from exposure to trace elements concentration in drinking water resources of the Central Ganga Alluvial Plain (CGAP), northern India. The estimates for were generated using analysis of groundwater samples (n = 100) collected from the Lucknow monitoring area to map the predicted area of health risk. The predicted probability maps have reclassified into a unified scale to generate Trace Element Risk Index (TERI), which has further integrated with human population count data to generate Health Risk Index of Lucknow. The results indicate that the risk is potentially alarming in urban areas as relatively high there are referring to the local (point) sources of contamination. Approximately 23.15% human population residing in about 69.77% of the total area is at moderate-to-high health risk probability. The findings of this study could help planning substantial remediation measures on long-term basis.

Modeling Groundwater Nitrate Contamination Using Artificial Neural Networks

The scope of the present study is the estimation of the concentration of nitrates (NO3−) in groundwater using artificial neural networks (ANNs) based on easily measurable in situ data. For the purpose of the current study, two feedforward neural networks were developed to determine whether including land use variables would improve the model results. In the first network, easily measurable field data were used, i.e., pH, electrical conductivity, water temperature, air temperature, and aquifer level. This model achieved a fairly good simulation based on the root mean squared error (RMSE in mg/L) and the Nash–Sutcliffe Model Efficiency (NSE) indicators (RMSE = 26.18, NSE = 0.54). In the second model, the percentages of different land uses in a radius of 1000 m from each well was included in an attempt to obtain a better description of nitrate transport in the aquifer system. When these variables were used, the performance of the model increased significantly (RMSE = 15.95, NSE = 0.70). For the development of the models, data from chemical and physical analyses of groundwater samples from wells located in the Kopaidian Plain and the wider area of the Asopos River Basin, both in Greece, were used. The simulation that the models achieved indicates that they are a potentially useful tools for the estimation of groundwater contamination by nitrates and may therefore constitute a basis for the development of groundwater management plans.

Hydrogeochemical characterization and groundwater quality assessment: a case study of the alluvial aquifer in the Middle Western Cheliff (Algeria)

ABSTRACT The Middle Western Cheliff plain hosts an important alluvial aquifer that is exploited for various uses including drinking water supply, irrigation and industry. This study aims to provide a hydrogeochemical characterisation of groundwater by using statistical methods and binary diagrams, as well as to evaluate the physico-chemical quality of groundwater by using the water quality index (WQI). Moreover, parametric indices such as SAR and %Na were used to evaluate the suitability of groundwater for irrigation. The hydrochemical approach based on results of 45 analyses of groundwater samples for the dry period 2019 enabled the determination of the most dominant chemical facies, which was chloride, sulphate, calcic and magnesium. The binary diagrams used indicated that the water-rock interaction and the evaporitic phenomenon are major geochemical processes that control the mineralisation of groundwater. The evaluation of groundwater quality for drinking water supply using WQI provided results with values ranging from 45.95 to 194.78, and above 60% of samples were classified into the category of excellent to good quality (WQI < 100), while the remaining 40% of water samples were classified in the category of poor quality for drinking (WQI > 100). However, the quality of groundwater is mostly acceptable for irrigation, mostly for plants with salinity-tolerant in drained soils.

Statistical Analysis of Groundwater sample of Sirohi village of Neemkathana block of Sikar (Rajasthan) India

In this study, the statistical analysis of groundwater of Sirohi village of Neemkathana block, Sikar (India) has been presented. Groundwater samples were taken from the se-lected sites strictly as per BIS norms. The TDS level of Sirohi village was found to be more than the acceptable limit of 500 mg/L. The higher TDS will affect human health. Neemkathana block in Rajasthan is a semi-arid zone, due to a continuous decrease in the value of rainfall, the rate of recharge of the water aquifer is imbalanced by yield. The average discharge from wells in alluvium ranges from 40m3/day to 90m3/day. Such kind of situation makes contamination to be at the extreme.

The origin of Uranium in groundwater of the eastern Halkidiki region, northern Greece

Uranium (U) pollution in groundwater has become a serious problem worldwide. Even in low concentrations, U has both radiological and toxicological impacts on human health. In this study an integrated hydrogeological approach was applied to conceptualize an aquifer system, and determine the origin of U detected in the aquifer of the eastern Halkidiki region in northern Greece. Data from measurements of groundwater level and hydrochemical and stable isotope analyses of groundwater samples were applied to perform geochemical modeling and multivariate statistical analysis. The modeling and statistical analysis identified three hydrogeochemical groups within the studied hydro-system, and U(VI) as the dominant U species. The first group is linked to the deeper aquifer which is characterized by water-rock interactions with weathering products of granodiorite. In this group the dominant U species is uranyl phosphate and U concentration is 3.7 μg/L. The upper aquifer corresponds to the second hydrogeochemical group where U concentrations are mainly influenced by high concentrations of nitrogen species (NO3− and NO2−). Factor analysis further discriminated the upper aquifer into a saline coastal zone and an inland zone impacted by agricultural activities. The third hydrogeochemical group presents the highest concentration of U (up to 15 μg/L) in groundwater and corresponds to the internal aquifer system. The U within this system is triggered by the presence of Mn2+, while the long residence time of the groundwater contributes synergistically to the hydrogeochemical process. Manganese triggers U oxidation in parallel with Fe2+ precipitation that acts as a regulator of U concentration. Groundwater depletion of the upper aquifers promotes the up-coning of geothermal fluids from fault zones leading to increased concentrations of U in the mid-depth aquifers.

Use of Multidisciplinary Approaches for Groundwater Recharge Mechanism Characterization in Basement Aquifers: Case of Sanon Experimental Catchment in Burkina Faso

In Burkina Faso, the basement aquifers represent a major asset in terms of quantity and quality, for both drinking and irrigation purposes for rural populations. They provide water resources that can guarantee the long-term needs of the populations, provided that a sustainable management policy for these resources is adopted. Yet, any groundwater resource management policy is necessarily linked to a better knowledge of aquifer recharge mechanisms, which is yet to be fully assessed in the Sahelian basement area. The objective of this study was to characterize the recharge mechanism within the experimental site of Sanon, located in the basement zone in Burkina Faso, using a coupling of hydrodynamic and chemical approaches. The hydrodynamic approach consisted of monitoring the spatial and temporal distribution of the piezometric levels of the aquifers along a north–south and east–west transect and determining soil infiltration capacity. The hydrochemical characterization of the aquifers was carried out through an analysis of groundwater samples from the concerned aquifers and daily tracing of the electrical conductivity of the aquifer water. The cross-analysis from the results of the implemented approaches shows a direct recharge mechanism through rainwater infiltration in the central valley, an indirect recharge mechanism in the lowlands, and a recharge mechanism by lateral transfers in the peripheral aquifers of the Sanon experimental catchment. The existence of a piezometric dome reveals in the central valley a zone of preferential recharge and water movement. The water of the central valley is the least mineralized with electrical conductivities below 100 µS/cm. This mineralization follows the direction of the water flow.

Groundwater deterioration in Akhmim District, Upper Egypt: A Remote Sensing and GIS investigation approach

Groundwater has a special significance in Akhmim area as it is used mainly in various purposes. However, groundwater is currently threatened by pollution from different sources. Therefore, detailed field investigations, in addition to Geographic Information Systems and remote sensing techniques are integrated to study the main sources of deterioration in groundwater quality and proposing practical solutions for mitigation and remediation. Based on the Modified Normalized Difference Water Index (MNDWI) and physicochemical analysis of groundwater samples, areas that contribute to groundwater deterioration have been identified. The results showed that the main causes of groundwater deterioration are the use of sewage rooms and injection wells to get rid of sewage especially in rural areas and scattered settlements, discharging liquid industrial wastes into the ground without proper treatment, the random exploitation of groundwater, and the use of wastewater in agriculture in a random manner. The results of the physicochemical analysis of groundwater samples confirmed the sources of deterioration identified by satellite images and field studies. To avoid groundwater degradation, strict restrictions need to be applied on the use of untreated or treated wastewater for irrigation, sewage networks have to be established in all residential areas, and factories must treat wastewater before discharging it.

Appraisal of protectivity and corrosivity of surficial hydrogeological units via geo-sounding measurements.

The surface resistivity method was used to appraise the protectivity of hydrogeological units and corrosivity of the top soil in Obot Akara County, southern Nigeria. A total of 28 vertical electrical sounding (VES) was undertaken in the area using the Schlumberger electrode configuration. The results of the VES data interpretation reveal 3 to 4 geoelectric layers in the study area. The resistivity of the first layer interpreted as the Motley top soil ranges from 34.7 to 929.7 Ωm with a mean value of 381.1 Ωm. The third layer, with a resistivity range of 99.4 to 2716.7 Ωm, constitutes the aquifer unit in most communities in the area, with an average thickness of 58.3m, while the fourth layer penetrated in most communities has a resistivity range of 216.1 to 1475.7 Ωm with a mean value of 657.5 Ωm. The longitudinal conductance and resistivity reflection coefficient of the aquifer protective layers vary from 0.04 to 0.76 mhos and - 0.74 to 0.93, respectively. Analysis of these results shows that 89.3% of the hydrogeological units in the area is weakly/poorly protected, 10.7% has moderate to good protection, while 85.7% of the top soil at the sounding stations is noncorrosive and 14.3% is slightly to moderately corrosive. The implication of these results is that most of the hydrogeological units in the area are likely prone to contamination in particular by some ferrugenized materials from the overlying layers. Also, underground metal storage tanks and galvanized and steel pipes can be buried in the topmost layer in most communities in the area without any risk of failure. Although these findings are very promising especially in groundwater management and exploitation in the area, hydrogeochemical and microbiological analyses of groundwater samples from available boreholes are recommended to corroborate the results.

Occurrence, distribution, and prediction of iron and manganese in groundwater of opencast mines: an example from Inner Mongolia, China.

Based on the geological and hydrologic data, the generation, enrichment, and transportation of iron (Fe) and manganese (Mn) ions in Yimin open-pit mining area were investigated using water quality analysis of groundwater samples, Statistical Product and Service Solutions (SPSS) principal component analysis, and geostatistics analysis by Geographic Information System (GIS). The water quality test results showed that the groundwater of this area was mainly the Na-Ca-HCO3 type, and the content of Fe and Mn ions significantly exceeded the national standard. The groundwater in the mining area was strongly affected by human activity, deep groundwater mixing effect, and water-rock interaction associated with mining activities. It was also found that Fe and Mn in the research area had a large variation in spatial distribution. On the whole, Fe and Mn ion concentrations found in the groundwater to the north of the research area were higher than those in the south area, with the mining area as the dividing line. The removing of non-mineral layer and the draining of gushing water in the mining area resulted in the formation of a water funnel and the strengthening of an effect between each aquifer. The change of hydrogeological and redox conditions in the mining area promoted the dissolution of Fe and Mn in soil and stratum and migration in groundwater.

Assessment of Groundwater Quality in the Jajrood River Basin, Tehran, Iran: A Coupled Physicochemical and Hydrogeochemical Study

The physicochemical composition of groundwater are affected by the quantity and quality of surrounding aquifers which are in turn recharging from adjacent river waters. In the present study, 20 surface and 16 groundwater samples were collected in pre- and post-monsoon seasons from Jajrood river basin, Tehran, Iran. The samples were analyzed for totally 18 physicochemical water quality characteristics to assess the river and groundwater qualities. Hydrogeochemical analyses of groundwater samples were also performed to determine the water quality index (WQI) for drinking use and to evaluate factors governing the water quality characteristic in the study area. Accordingly, Piper diagram as well as Gibbs and Chadha’s plots were applied to assess seasonal variations in hydrochemical facies and to evolve the hydrochemical processes in the basin. Sub – surface soil samples were also examined with respect to the structure, elemental composition and multi- elemental trace analysis. Results showed the abundance of major ions in the order of Ca+2 > Na+ > Mg+2 > K+, and HCO3- > SO42- > Cl- > NO3- > F-. In general, all drinking groundwater samples met WHO permissible limits except for chemical oxygen demand (COD) and HCO3-. Moreover, the water is categorized as Ca-Mg-HCO3 type. Sub surface soil analyses demonstrated quartz and calcium carbonate as the main phases of soil structure suggesting the enrichment of groundwater with temporary hardness. Overall, the groundwater quality was suitable for drinking uses and agricultural activities.

Characterization of Ground Water Quality in Southern and Northern Region of Zanzibar Island

Millions of people from different countries depend on groundwater, which might contain elevated levels of unhygienic constituents. Poor quality of drinking water in many countries has been forcing people to use bottled water. In the present study, groundwater samples were collected in November 2014 leading to twenty-nine analysis of groundwater samples. The primary objective of this paper is to study the selected groundwater quality parameters as an establishment of preliminary baselines on groundwater constituents. A total of twenty nine water samples were collected (fourteen and fifteen samples from North and South regions of Zanzibar Island respectively. Physical parameters (Turbidity, oxidation-reduction potential ORP, Eh, pH, total dissolved soild TDS, salinity, and Electrical conductivity (EC) were determined in situ using Horiba multiparameters digital meters. Analysis of anions (NO3-, Br- , SO42-, F-, NO2-) was carried out using Ion chromatography (IC). Nitrite and nitrate for some water were below detection limit (BDL) The order of relative abundance for anions in samples collected at Northern region of Zanzibar Island, was NO3- &gt; Br- &gt; SO42- &gt; F- &gt; NO2- , while for the Southern region the order was NO3- &gt;Br- &gt; NO2- &gt; SO42- &gt; F- . In both regions, the orders for other parameters were; Turbidity &gt; pH &gt; salinity; and EC &gt;TDS &gt; ORP &gt; Eh. Almost all the measured parameters were within the WHO guidelines for drinking water. However, for nitrate and bromide, the percentage that exceeded the WHO limit was 7%, and 10.3% respectively. Based on toxicological perspective, although few samples had concentrations above groundwater quality criterion it is fundamental to estimate the intake by humans through the drinking water pathways.