Article

# The hydrochemistry of groundwater in the Densu River Basin, Ghana

Authors:
• School of Nuclear and Allied Sciences Ghana Atomic Energy Commission (GAEC)
• Ghana Space Science and Technology Institute
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## Abstract

Hydrochemical analyses of groundwater samples were used to establish the hydrochemistry of groundwater in the Densu River Basin. The groundwater was weakly acidic, moderately mineralized, fresh to brackish with conductivity ranging from of 96.6 microS cm(-1) in the North to 10,070 microS cm( - 1) in the South. Densu River basin have special economic significance, representing the countries greatest hydrostructure with freshwater. Chemical constituents are generally low in the North and high in the South. The order of relative abundance of major cations in the groundwater is Na+>Ca2+>Mg2+>K+ while that of anions is Cl->HCO3->SO4(2-)>NO3-. Four main chemical water types were delineated in the Basin. These include Ca-Mg-HCO3, Mg-Ca-Cl, Na-Cl, and mixed waters in which neither a particular cation nor anion dominates. Silicate weathering and ion exchange are probably the main processes through which major ions enter the groundwater system. Anthropogenic activities were found to have greatly impacted negatively on the quality of the groundwater.

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... X = 6.55) ‫܀‬ EC ranged between 134 and 7780, X = 728.16 ‫܀‬ Elevated levels of NO 3 -, Mn and Fe ‫܀‬ Main water types; Ca-Mg-HCO 3 , Na-Cl, mixed water types ‫܀‬ Farming, washing and sewage disposal within the basin, perhaps, have great impact on the quality of groundwater Fianko et al. (2010) ‫܀‬ Conducted across the entire basin ‫܀‬ Weakly acidic water (pH = 4.37-7.63, X = 6.49) ‫܀‬ Order of dominance for cations; Na + >Ca 2+ >Mg 2+ >K + and anions; Cl ->HCO 3 >SO 4 2->NO 3 -‫܀‬ Main water types; Ca-Mg-HCO 3 , Ca-Cl, Na-Cl, mixed water types ‫܀‬ Silicate weathering and ion exchange impact negatively on quality Gibrilla et al. (2010) ‫܀‬ Conducted in northern part of Densu river basin ‫܀‬ Fresh and low in TDS (49-361 mg/l) ‫܀‬ Slightly acidic to alkaline (pH = 5.58-7.48, ...
... There Fig. 6. Conceptual groundwater flow (Modified after Alfa, 2010;Fianko et al., 2010;Gibrilla et al., 2010;Adomako et al., 2011a,b;Yidana et al., 2014Yidana et al., , 2018. is a general dominant north-south flow direction, and some northeast-southwest flow patterns as well, with intermittent local flow patterns in the central sections of the basin which is generally undefined (Fig. 6). The northern parts of the basin have the highest elevations (reaching 700 m), and has been noted as the recharge zone in the basin Gibrilla et al., 2010;Yidana et al., 2014). ...
... Similarly, mining activities in the Birimian formation around the East Akim district, sand winning, stone quarrying, and illegal fishing methods such as the use of explosives and chemicals contribute to the diminishing water quantity and quality problems in the basin (WRC, 2007). Several other studies have mentioned indiscriminate waste disposal in the basin as a source of worry for the environment and a major factor in the pollution of both surface and groundwater bodies (WRC, 2007;Fianko et al., 2010;Adomako et al., 2011a;Yidana et al., 2018). Waste discharge to surface water bodies, especially rivers has been predicted to increase by up to 10 times the presents amount (WRC, 2007). ...
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Study region Densu River Basin in Ghana, West Africa. Study focus This paper reviews aquifers and groundwater resources in the Densu River Basin based on several past studies which adopted hydrochemical, numerical modelling, geostatistical techniques, and several other conventional methods with particular focus on the hydrogeological and hydrochemical characteristics, general water quality and quantity challenges, and the projections thereof. New hydrological insights Groundwater recharge was revealed to far exceed the abstraction and offer great potential for other uses. However, the recharge rate is at the risk of diminishing due to climate change threats such as falling runoff and rainfall amounts, rising atmospheric temperatures, and population growth. The groundwater is generally of acceptable quality for domestic, agricultural and industrial purposes. The hydrochemistry of the groundwater is principally controlled by silicate weathering, ion exchange and sea water intrusion. Groundwater contamination due to domestic waste discharge, mining and agricultural activities also feature significantly in the basin. The emerging issues identified in this review include rising water demands, impacts of climate change on groundwater resources, anthropogenic effects on groundwater quality and inadequate knowledge of the underlying aquifers. Integrated hydrogeological assessment of the basin conducted in a holistic manner will therefore be necessary to properly understand the aquifers and groundwater resources in the basin for informed water management decisions.
... Hydrogeochemical and multivariate statistical techniques have also been jointly employed in groundwatersurface water quality evaluation Yidana et al., 2010;Affum et al., 2015). Additionally, Kortatsi (2006), Kortatsi (2007), Helstrup (2007), Fianko et al. (2010), Tay et al. (2017), and Ganyaglo et al. (2017) applied hydrochemistry and hydrogeochemistry to groundwater appraisal in southern Ghana and southern Togo, Accra plains, Ankobra Basin, Densu River Basin, Savelugu-Nanton District, northern Ghana, Lower Pra Basin, and Ochi-Narkwa Basin respectively. The hydrochemistry of groundwater in Ghana is generally noted to be influenced by silicate weathering, exchange of cations and anthropogenic activities such as agricultural activities, septic and waste discharges, mostly where the aquifers are unconfined and relatively shallow. ...
... Conventional hydrochemistry has been specifically applied in Ghana (e.g. Acheampong and Hess, 1998;Yidana et al., 2008;Banoeng-Yakubo et al., 2009;Fianko et al., 2010) in the study of water resources. The approach has been used by some researchers for surface water and groundwater studies in parts of the Volta Basin in Ghana but not specifically in the study area (Kortatsi, 1994;Nerquaye -Tetteh, 1993;Agyekum, 2004;Karikari et al., 2007;Yidana et al., 2007;Gampson et al., 2014). ...
... Hydrogeochemical and multivariate statistical techniques have also been jointly employed in groundwatersurface water quality evaluation Yidana et al., 2010;Affum et al., 2015). Additionally, Kortatsi (2006), Kortatsi (2007), Helstrup (2007), Fianko et al. (2010), Tay et al. (2017), and Ganyaglo et al. (2017) applied hydrochemistry and hydrogeochemistry to groundwater appraisal in southern Ghana and southern Togo, Accra plains, Ankobra Basin, Densu River Basin, Savelugu-Nanton District, northern Ghana, Lower Pra Basin, and Ochi-Narkwa Basin respectively. The hydrochemistry of groundwater in Ghana is generally noted to be influenced by silicate weathering, exchange of cations and anthropogenic activities such as agricultural activities, septic and waste discharges, mostly where the aquifers are unconfined and relatively shallow. ...
... Conventional hydrochemistry has been specifically applied in Ghana (e.g. Acheampong and Hess, 1998;Yidana et al., 2008;Banoeng-Yakubo et al., 2009;Fianko et al., 2010) in the study of water resources. The approach has been used by some researchers for surface water and groundwater studies in parts of the Volta Basin in Ghana but not specifically in the study area (Kortatsi, 1994;Nerquaye -Tetteh, 1993;Agyekum, 2004;Karikari et al., 2007;Yidana et al., 2007;Gampson et al., 2014). ...
... It interprets evolutionary trends by providing additional information on groundwater hydrogeochemical facies and explains water types and reverse and direct ion exchange processes (Aly et al., 2015). In this plot, total cations (Na + + K + , Ca 2+ , Mg 2+ ) versus total anions (HCO 3 − + CO 3 − , SO 4 2− , Cl − ) in percentage milliequivalents/litre are plotted (Fianko et al., 2010). For better understanding, pH and TDS (mg/L) are introduced to the diagram edges. ...
Article
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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. Graphical abstract
... In fact, this approach operates entirely on the assumption that the outliers are not part of the background concentration but rather from another source (Bulut et al., 2020). However, adopting only these tools in estimating the NBL in this study will be problematic since the anthropogenic activities in the study area are known to have had adverse effect on the groundwater (Fianko et al., 2010). This study therefore demonstrates the feasibility of estimating the NBL of NO 3 -N in the Densu basin using the kernel density estimation (KDE) and Gaussian mixture clustering models (GMM). ...
Article
The study assesses the extent of nitrate pollution in the Densu Basin because of itspredominance in agriculture and urbanized vicinities by employing robust techniques for estimating both the natural background and human-induced concentrations. Statistical methods used to estimate these concentrations are the pre-selection method, graphical approach (probability plot), non-parametric approach (kernel density estimation), and parametric approach (Gaussian mixture model). The study shows that the Gaussian mixture model is robust enough in determining the spectral distribution and clustering of the NO3-N concentration in the basin. It estimated the natural background and human induced concentration at 1.7±1.3 mg/L and 9.8±5.6 mg/L, respectively. The results show that the natural background concentration in the basin is more dominant and hence, conducive for drinking. It’s revealed that 26% of anthropogenic sources have leaked into the natural groundwaters of the Basin. The data suggest multiple sources of NO3-N concentration in the groundwater.
... All of the groundwater and surface water samples in the study region fell well below the 1:1 line (Fig. 4a), with the regression for all samples being negatively correlated (not shown). Very few of the samples in the Mid and South sections plotted close to the line indicating that processes other than halite dissolution are dominant and the source for Na may likely include weathering of silicate minerals in the aquifer (Fianko et al., 2010;Kumar et al., 2014). Deep saline sources could also contribute Na and Cl to the aquifers. ...
Article
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The groundwater quality of the Upper Pearl River Watershed (UPRW) and surface water quality of the basin’s outlet, Ross Barnett Reservoir (RBR), are critically important because of growing demands for drinking, agriculture, and industrial use in the region. To identify factors affecting water quality and characterize the surface water outlet and the watershed’s groundwater, geochemical and statistical analyses were performed using results from various hydrogeochemical parameters. Based on surface geology, groundwater samples analyzed (n = 51) within the watershed were partitioned into three recharge zones: North, Mid, and South. Precipitation and rock-water interactions were identified to dominantly influence the groundwater chemistry in the region. The chemistry of the surface water samples (n = 9), on the other hand, was influenced more by precipitation with minor contribution from the proximal aquifer system. Principal component analysis (PCA) revealed that two groundwater recharge zones and RBR samples exhibited significant clustering. The groundwater had a complex array of parameters influencing its chemistry owing to diverse properties, including Na, Ca, Mg, alkalinity, and conductivity. Comparing land use at the sub-watershed level with the water quality parameters showed that agriculture and development could have contributed nitrate, especially to the groundwater in the south zone. However, a general lack of distinct relationship between land use and water quality, along with detection of excess nitrate in select wells suggested that the water in the region was likely affected by point sources, such as poultry farms. The research recommends evaluating point sources of pollution to cater to future water management in the region.
... Where five of the brands of sachet drinking water had their pH values lower than the permissible limit, ranging from 5.21 to 5.93, only one (hephzzy) sachet water brand had pH valued within the permissible limit (Okechukwu et al., 2015). Acidic water has also been recorded in other parts of Africa, including Guinea-Bissau (Bordalo and Savva-Bordalo, 2007;Haruna et al, 2005); Ghana (Adomako et al, 2014;Fianko, 2010aFianko, , 2010b; Nigeria (Nduka and Orisakwe, 2011;Omezuruike, 2008), South Africa (Zamxaka, 2004); and Tanzania (Shayo et al, 2007). ...
Article
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This study was conducted to assess the physical, chemical, and bacteriological parameters of five-brand of sachet water, and their source point consumed in Bo city, southern Sierra Leone. The physical parameters include: pH, temperature, turbidity, total dissolved solid, and conductivity; chemical parameters include: Residual Chlorine, Magnesium, Potassium, Nitrite, Ammonia; and bacteriological parameters include: Escherichia coli, fecal coliform, and non-fecal coliform. Samples were collected and conveyed to the laboratory within 30 min. The result analyzed shows that the physical, chemical, and bacteriological parameters of the Spring Box, and the five-brand were in conformity with the World Health Organization (WHO) guidelines. However, the pH of four-brand and the Spring Box fell below WHO standards (6.50-8.50), only Tee Spring had a pH that is within the permissible limit. The temperature of the Spring Box and the five-Brand fell above the WHO standard (25.00°C). It can be said that the physical, chemical, and bacteriological parameters of all the five-brand and the Spring Box, are all within the WHO guidelines limit, and therefore fit for drinking.
... Where five of the brands of sachet drinking water had their pH values lower than the permissible limit, ranging from 5.21 to 5.93, only one (hephzzy) sachet water brand had pH valued within the permissible limit (Okechukwu et al., 2015). Acidic water has also been recorded in other parts of Africa, including Guinea-Bissau (Bordalo and Savva-Bordalo, 2007;Haruna et al, 2005); Ghana (Adomako et al, 2014;Fianko, 2010aFianko, , 2010b; Nigeria (Nduka and Orisakwe, 2011;Omezuruike, 2008), South Africa (Zamxaka, 2004); and Tanzania (Shayo et al, 2007). ...
... Expanded Durov diagram was used to show the clustering of groundwater point data to specify the samples that have similar compositions. In this diagram major cations (Ca 2+ , Mg 2+ , Na + , K + ) and anions (CI − , SO 4 2− , HCO 3 − ) were plotted in terms of percentage by converting the chemical facies concentration (meq/L) (Guler et al., 2002;Fianko et al., 2010). The major cations and anions plotted (Durov, 1948) as percentages of miliequivalents in two base triangles. ...
... Therefore, determination of groundwater qualityin this area is important to effectively allocate the groundwater resources for agricultural and industrial purpose. In this regard, geo-chemical studies of groundwater provide a better understanding for possible changes in groundwater quality due to rock-water interaction or any type of anthropogenic influence [1][2][3]. ...
Conference Paper
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This paper aims to investigate the groundwater quality for agricultural and industrial purposes in southern Tehran, Iran. In this regard, sampling was performed in 20 wells. Results indicated that about 25% groundwater samples (wells) had electrical conductivity(EC) higher than 3000 and therefore they are harmful for agricultural purposes. For the majority of samples, the sodium adsorption ration (SAR) was within the acceptable range and thus suitable for irrigation. Residual sodium carbonate (RSC) of all the water samples was negative that indicates the suitability of all wells for irrigation application. Also, findings suggested that about 80% of wells were not suitable to use for industrial purposes based on calculated saturation index of calcium carbonate.
... Bounded by the Okrudu, Odaw, Volta, and Birim basins to the west, east, north, and northwest respectively, the Densu River which is about 116 km long originates from the Atewa-Atwiredu mountain range near Kibi in the East Akyem District of Ghana and drains into the Gulf of Guinea near Bortianor, West of Accra . The basin is underlain by Precambrian granitoids made up largely of Cape Coast granite and granodiorites and little Upper Birimian and Togo formation (Fianko et al. 2010). The main tributaries of the Densu River include rivers Adeiso, Nsakyi, Dobro, Aprapon, Mame, and Kuia. ...
Article
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Crustaceans, mollusks, and fish are wetland resources that constitute an important source of protein and foreign exchange for the Ghanaian population, and many species of these are sold in the open market and restaurants, yet studies on their heavy metal contents are generally scarce. This paper evaluates the levels of mercury in five species of crustaceans, two species of mollusks, and ten species of fish inhabiting three river basins with different catchment activities in Ghana. These include the Ankobra Basin, characterized with mining and agriculture, Densu Basin, associated with urban waste discharges and agriculture, and Lower Volta River Basin, associated with agricultural activities. Mercury concentration was highest in Ankobra (2.5 ± 2.59 μg g(-1)) followed by Densu (1.75 ± 1.35 μg g(-1)) and Volta (0.74 ± 1.46 μg g(-1)). The mercury load of the organisms range from <0.1 to 4 μg g(-1) with the highest load in Cynoglossus senegalensis at Ankobra. Except for Panaeus notialis from Densu and Ankobra, and three other species from Ankobra (Tympanotonus fuscatus, Cardisoma armatum, Callinectes amnicola) in which mercury was not detected, mercury loads of all the organisms were above the permissible limit of 0.5 mg kg(-1) established by Commission Regulation-EC (2006) for fishery products and muscle meat of fish. Weekly quantities of crustaceans and mollusks considered safe for consumption by adults ranged from 88 and 1000 g while that of the fishes were between 70 and 700 g (on a dry weight basis) depending on the species. It was clear that some caution needs to be exercised in the consumption of Ghana's fresh and brackish water fisheries.
... Although the pH of water is not considered to be an immediate health issue, the acidity of the water can damage pipes and can release those minerals into wells, potentially causing serious health problems (WHO, 2011).A previous study of the water quality of wells in Bo that are used as residential drinking water sources found levels of acidity very similar to those observed in this study (Jimmy et al., 2012). Acidic water has also been reported from other parts of Africa, including Guinea-Bissau (Bordalo, 2007; Haruna, 2005), Ghana (Adomako, 2008; Fianko, 2010a; Fianko, 2010b), Nigeria (Nduka, 2011; Omezuruike, 2008), South Africa (Zamxaka, 2004), and Tanzania (Shayo, 2007). One of the factors that may affect the safety and quality of water is the knowledge of water workers. ...
Article
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[DOI: 10.4314/sljbr.v8i1.5] Background: Many people who lack reliable access to a quality and safe drinking water source in or near the home rely on commercial drinking water products, such as machine-filled sachet water, that may be of variable quality. Methods: A participatory geographic information system was used in conjunction with distribution point and vendor census in the study area to identify a total of 36 water sources across Bo city that are used for commercial water production. These include 6 water sources and the production facilities for 10 brands of machine-filled factory-produced water sachets as well as the 10 sources and finished samples for 10hand-tied plastic-bagged water producers. Water samples from all 16 water sources and 20 commercial water products purchased from randomly-selected retail outlets and street vendors were tested for microbiological and physicochemical properties. Workers at all of these facilities were also interviewed about their knowledge and practices. Results: All of the machine-filled sachet waters were free of microbial contamination, but several of the hand- tied water sachets, all filled from unlined local wells, and had coliform bacteria. Both machine-filled sachet water and hand-tied sachet water had pH levels that were below the World Health Organization’s recommended range. Water with acidic pH can cause corrosion of the metal pipes used with wells and can release those potentially harmful minerals into drinking water. Water factory workers used a variety of water treatment methods to purify their products; hand-tied sachets generally used only cloth filters to purify the water, and often stored water in open containers. Conclusions: Improved quality of commercial water products would improve health in Sierra Leone.
... It is obvious that though DRASTIC seems to be over-parametised with the number of datasets, it gives a reasonable judgment of the basin conditions as at present. This is because other studies in the basin have indicated that there exists a relative high potential of the groundwater resources in the basin(Dickson Adomako, Gibrilla, Akiti, Fianko, & Maloszewski, 2011;D Adomako, Osae, Akiti, Faye, & Maloszewski, 2011;Fianko, et al., 2010) and that the groundwater was highly susceptible due to the geographical conditions and impact from human activity. This qualitatively describes the groundwater bearing rock as vulnerable to the high human activity in this basin. ...
Article
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The Densu River Basin is one of the important basins in Ghana. A large number of residents in this basin are dependent on groundwater for their livelihood. However, with the growing population, urbanization and impact of climate change, it is imperative to develop ways to protect and manage the limited groundwater resource that is supporting the communities. As a result, this paper assessed the groundwater vulnerability by comparing two methods – the Depth to water, net Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and hydraulic Conductivity DRASTIC an the Aquifer Vulnerability Index (AVI). The results show that DRASTIC is more precise and representative of the groundwater vulnerability in the basin. The AVI statistically show a relatively lower risks compared to DRASTIC. It is recommended, AVI which is oversimplified may be useful for larger basins.
... The waters in the granites have pH values ranging from 5.7 to 7.64. Similar results were obtained by Fianko et al. (2010) and Ganyaglo et al. (2010) in the Cape Coast Granitoids of the Densu River Basin. The neutral to slightly acidic waters in the granitoids may be due to the dissolution of silicates and carbonates (Pelig-Ba 1989). ...
Article
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This paper assesses groundwater in the Ga West Municipal Area of Ghana using hydrogeochemistry and isotope approaches. High salinity groundwaters are obtained in the municipality which poses problems for current and future domestic water supply exploitation. The increase in salinity is related to the dissolution of minerals in the host rocks and the evaporative concentration of solutes. The dominant groundwater composition in both shallow and deep wells sampled is Na–Cl. The concentration of the Na–Cl was observed to increase substantially with well depths. The mixing of freshwater of the shallow hand dug wells with that of saline water of the deep boreholes was noted in the shift from Ca–HCO3 facies to Ca–Cl facies. Schoeller diagram showed that groundwater in the study area is recharged from a similar source. The Schoeller diagram also showed the gradual increase in concentration of the major ions with depth. This leads to salinization in the deep boreholes. The oxygen and hydrogen isotope compositions in the groundwater samples suggest that groundwater recharge is of meteoric origin with few samples showing evidence of evaporation. An average deuterium excess of rainfall of 14.2 ‰ was observed, which indicates the significance of kinetic evaporation due to low humidity conditions prevalent in the study area. The d-excess also indicates modern recharge along the foothills of the Akwapim-Togo Ranges.
... Togo formations is dominantly a metamorphic and highly comprised of three distinctive lithology assemblages which quartzites are the main rock types followed by the strongly tectonised phyllites and serpentinite (Ahmed et al., 1977; Banoeng-Yakubo et al., 2010). Other rock types of the Togo Formations include sandstones, shales, quartz schist, silicified limestones, talc mica schist (Richmond et al., 2010; Darko et al., 2010). Adentan is located in the area where the major solids aquifers or rocks types are Dahomeyan series mentioned above with undifferentiated (mainly schists and gneisses). ...
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The aim of this present study was to assess natural radioactivity levels in selected groundwater (boreholes and wells) used as domestic purposes in particular and drinking as well in some communities in Adentan and Abokobi areas in Greater Accra region of Ghana. This was achieved by first measuring the activity concentration of 222Rn, 40K and 232 232Th in groundwater samples using High-Purity Germanium (HPGe) detector. These concentrations of 40K, 222Rn and 232Th were used with their ingested dose conversion factors to estimate annual effective dose for Adult members of public due to consumption of the groundwater. The estimated average annual effective dose due to consumption of 40K, 222Rn and 232Th in the water samples from Adentan and Abokobi were 113.007±3.940 and 76.568±2.321 μSv/y, respectively. These were compared with the estimated average annual dose due to ingestion of nuclides in water by the WHO (100 μSv/y) and the estimated average dose due to ingestion of radionuclides in food and water (290 μSv/y) by UNSCEAR (2000). They are found within the range even though Adentan value is slightly higher than the WHO average value. The results show that consumption of groundwater may not pose any radiological health hazard to the public.
... The acidity of the water sources in Kulanda Town is similar to other water sources in Africa, including Uganda (Haruna et al. 2005;Bordalo and Savva-Bordalo 2007) and Guinea-Bissau (Haruna et al. 2005;Bordalo and Savva-Bordalo 2007). But studies from Ghana (Adomako et al. 2008;Fianko et al. 2010a, b;Nartey et al. 2004), Nigeria (Ejechi et al. 2007;Jaji et al. 2007;Nduka and Orisakwe 2011;Omezuruike et al. 2008), South Africa (Zamxaka et al. 2004), and Tanzania (Shayo et al. 2007) indicated that acidic water is not uniformly found throughout the continent. Water with acidic pH can cause corrosion of the metal pipes used with wells and can release those minerals into wells, potentially causing serious health problems (WHO 2008). ...
Article
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Human health depends on reliable access to safe drinking water, but in many developing countries only a limited number of wells and boreholes are available. Many of these water resources are contaminated with biological or chemical pollutants. The goal of this study was to examine water access and quality in urban Bo, Sierra Leone. A health census and community mapping project in one neighborhood in Bo identified the 36 water sources used by the community. A water sample was taken from each water source and tested for a variety of microbiological and physicochemical substances. Only 38.9% of the water sources met World Health Organization (WHO) microbial safety requirements based on fecal coliform levels. Physiochemical analysis indicated that the majority (91.7%) of the water sources met the requirements set by the WHO. In combination, 25% of these water resources met safe drinking water criteria. No variables associated with wells were statistically significant predictors of contamination. This study indicated that fecal contamination is the greatest health risk associated with drinking water. There is a need to raise hygiene awareness and implement inexpensive methods to reduce fecal contamination and improve drinking water safety in Bo, Sierra Leone.
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In the present study, an attempt has been made to develop the dictate metrics using a multi-proxy approach, i.e., spatial-temporal analysis, statistical evaluation, and hydrogeochemical analysis for 45 water samples located in the Thamirabarani river basin in Tamil Nadu, India. In order to evaluate the aptness of developed metrics for agriculture and domestic needs, eleven years dataset was analyzed and compared with national and international standards. Monitoring and analysis results revealed that the concentration of calcium and chloride ion was on the higher side in all the selected locations. These higher values may be attributed to the regional point sources such as untreated water disposal and off-peak sources such as agriculture practices. The principal component analysis resulted in 84.2% of the total variance in the post-monsoon season dataset. The major analyzed cations and anions were observed in the following order: Na ⁺ > Ca ²⁺ > Mg ²⁺ > K ⁺ and Cl ⁻ > HCO 3 ⁻ > SO 4 ²⁻ > NO 3 ⁻ , respectively. Overall, this study revealed that the studied area's groundwater quality was significantly affected by the high salinity in the region, probably due to anthropogenic activities and unprotected river sites.
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Granitic aquifers, which occur in crystalline Basement bedrocks, are generally fresh and serve as potable water sources in many developing countries. In this study, we examine the chemical evolution processes, and water isotope geochemistry of a sparsely studied granitic aquifer in a sub-river watershed of the White Volta River Basin in West Africa. Our goal is to establish the sources of water that replenishes the aquifer - in a watershed dominated by irrigation farming - and to determine the most vulnerable areas that may be impacted by human activities and climate change. The results show that in most samples collected from the aquifer, the level of dissolved ions permits safe agricultural use and requires minimal treatment for domestic consumption. The aquifer water evolves from recharge water of Ca-Mg-HCO3, Ca-Na-Mg-HCO3/Cl type in the highlands of the watershed, to Na-Ca-Mg-HCO3, Na-Ca-Mg-HCO3/Cl and Na-HCO3 types in the discharge areas. Groundwater recharge is diffuse, and flow is continuous with little attenuation from the highlands to the lowlands. Water isotopes (δ2H and δ18O) show groundwater recharge comes mainly from rainfall and occurs throughout the basin. Tritium, ³H, measurements confirm diffuse recharge and suggest the aquifer contains recharge water, which are between the ages of less than 1 – 30 years. The assigned Hydrogeochemical Vulnerability Index (HVI) is confirmed with nitrate and tritium data and shows that the aquifer could be negatively impacted by climate change and land-use activities. A conceptual framework for aquifer recharge, flow, and vulnerability is presented to summarize our findings.
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Metal levels beyond stipulated thresholds are a considerable concern for environmental pollution regulators and public health administrators around the globe. Data is, however, lacking in most regions especially developing countries for practical policy decision making and management. In this study, we obtain 49 high-resolution soil cores from three vertical profiles in the Densu River Basin of Ghana and measured the concentrations of major and trace metals (Ca, K, Fe, Ti, Cr, Cu, V, Ni, and Zn). The aim was to examine and provide data on metal levels to serve as baseline information on mobilization studies for waste management. Geochemical methods for estimation of metal enrichment and accumulation were employed to determine enrichment and pollution, sources, and mobilization of the metals. Hierichical cluster and principal components analyses were used to examine metal associations and the effects soil physicochemical properties on the metals. The results show spatial variations in metal concentrations within and between individual soil profiles and are attributed to variability in soil formation processes and the locations where samples were collected, respectively. Moderate to high enrichment factors ( EF ) and geo-accumulation ( Igeo ) indices were observed for Vanadium (V) and Chromium (Cr) in all soil profiles indicating some level of anthropogenic interference leading to pollution possibly from vehicular and agricultural inputs. The Pourbaix diagrams, however, show that the Cr and V abundances may be natural. Our analysis also show that most of the metals investigated are of natural (i.e., geologic) origin but further investigations are recommended. The combination of field observations and established methods such as geochemical and statistical analyses have aided in extracting beneficial information from the small sample size.
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Hydrogeochemical methods were integrated to delineate the geochemical factors controlling fluoride (F-) contamination in groundwater at four sites in the districts of Lahore (Samada) and Kasur (Sari Chimba, Kot Maiga, and Chah Fatehwala) in Panjab province of Pakistan. Hydrochemical data and stoichiometric ratios indicate Na–Cl and Na–HCO3 as the dominant water types with silicate weathering influencing overall hydrogeochemistry of the study area. The groundwater F- concentrations ranged between 0.54 mg/L and 17.5 mg/L, with more than 70% samples having F- concentrations above the World Health Organization (WHO) provisional drinking water guideline (1.5 mg/L). Saturation indices determined that 100% samples were saturated with respect to calcite and 96% samples were undersaturated with respect to fluorite, indicating the influence of calcite precipitation on fluoride enrichment. A positive correlation was observed between fluoride with pH, Na+, and HCO3−, confirming that high fluoride concentrations were the result of weathering of silicate minerals and the exchange of OH- on clay surface under the alkaline pH conditions. The isotopic values of δ18O and δ2H in groundwater ranged from 9.14 to − 5.51‰ and 56.57 to − 39.5‰, respectively. The stable isotope data indicated the meteoric origin of groundwater with some evaporative effect, which is partly influencing groundwater quality such as high pH and salinity, as a result facilitating anion exchange (OH- for F-) on clays surface. The research indicates that the groundwater quality of the study area is not recommendable for drinking due to its high total dissolved solids (TDS) and elevated fluoride concentrations.
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Objectives: To assess the extent to which packaged water producers follow product registration procedures and to assess the relationship between product registration and drinking water quality in Accra, Ghana. Methods: Following preliminary analysis of a national water quality survey, 118 packaged sachet water samples were collected by sampling all brands sold by 66 vendors. A sample of vendors were selected from two high income and two low-income areas of Accra, Ghana. Sachet packaging and labelling details were recorded and compared to a regulatory database to assess product registration. All samples were weighed and tested for faecal indicator bacteria and selected physico-chemical parameters. Results: Product registration numbers and brand names could be matched to regulatory records for 77 out of 118 sachets (65.2%). All samples tested were compliant with national water quality standards for faecal indicator bacteria and nitrate. Brand registration was not associated with any of the quality indicators considered Conclusion: The results of this study suggest that whilst a substantial proportion of sachet water is sold without formal product registration, the microbial quality of the unlicensed water is consistently high in Accra, Ghana. Further examination of regulatory enforcement and monitoring will be needed to ensure sustained high water quality over time. <br/
Article
This study aims to identify the water source of a water-bursting disaster that occurred at the Longmen Gorge South Coal Mine ventilation adit on May 2011. The chosen approach includes the investigation of hydrogeochemical processes of major ions and a tracing test. The relative abundance of major ions is proposed to be Ca²⁺ > > K⁺+Na⁺ > Mg for cations and HCO3⁻ > > SO4²⁻ > NO3⁻ > Cl⁻ for anions. A piper diagram of the water samples demonstrates that they are of an HCO3-Ca water type. Principal component analysis implies that the hydrochemistry of water is a result of multiple factors. PC1 represents ion exchange and natural mineral weathering. PC2 and PC3 indicate hydrological processes of agricultural activities and evaporation, respectively. Cluster analysis of water samples is divided into four groups of clusters (group 1–group 4) and suggests a certain homology and similarity between water samples M1/M2 and S3/S5. The tracer breakthrough curves suggest that there is a large possibility that the injection points are connected with the monitoring points, consistent with the CA view. Analysis and research of the hydrogeochemistry of mine groundwater demonstrate that the use of PCA and CA is a feasible method of identifying the mine’s water-bursting source and determining the possibility of a water-bursting event.
Article
Insufficient understanding of the hydrogeochemistry of aquifers makes it necessary to conduct a preliminary water quality assessment in the southern region of Ordos Basin, an arid area in the world. In this paper, the major ions of groundwater have been studied aiming at evaluating the hydrogeochemical processes that probably affect the groundwater quality using 150 samples collected in 2015. The two prevalent hydrochemical facies, HCO3Mg·Na·Ca and HCO3Mg·Ca·Na type water, have been identified based on the hydrochemical analysis from Piper trilinear diagram. Compositional relations have been used to assess the origin of solutes and confirm the predominant hydrogeochemical processes responsible for the various ions in the groundwater. The results show that the ions are derived from leaching effect, evaporation and condensation, cation exchange, mixing effect and human activities. Finally groundwater quality was assessed with single factor and set pair methods, the results indicate that groundwater quality in the study region is generally poor in terms of standard of national groundwater quality. The results obtained in this study will be useful to understand the groundwater quality status for effective management and utilization of the groundwater resource.
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Leachate generated by open solid waste disposal sites contains substances likely to contaminate groundwater. The impact of potential contaminants migrating from leachate on groundwater can be quantified by monitoring their concentration and soil properties at specific points in the unsaturated zone. In this study, physical and chemical analyses were carried out on leachate, soil and water samples within the vicinity of the municipal solid waste disposal site at Abloradjei, a suburb of Accra, Ghana. The area has seen a massive increase in population and the residents depend on groundwater as the main source of water supply. Results obtained indicate alkaline pH for leachate and acidic conditions for unsaturated zone water. High EC values were recorded for leachate and unsaturated zone water. Major ions (Ca2+, Na+, Mg2+, K+, NO3 −, SO4 2−, Cl−, PO4 3− were analysed in leachate, unsaturated zone water, soil solution and groundwater while trace metals (Al, Fe, Cu, Zn, Pb) were analysed in both soil and extracted soil solution. Concentrations of major ions were high in all samples indicating possible anthropogenic origin. Mean % gravel, % sand, % clay, bulk density, volumetric water content and porosity were 28.8, 63.93, 6.6, 1 g cm−3, 35 and 62.7 %, respectively. Distribution of trace elements showed Kd variation of Al > Cu > Fe > Pb > Zn in the order of sequential increasing solubility. It was observed that the quality of groundwater is not suitable for drinking.
Article
This study examines groundwater quality along the Nandesari common effluent channel (Vadodara, Gujarat, India) designed for disposal of treated industrial effluents from the Nandesari industrial area. Groundwater samples have been collected from various available groundwater sources like hand pumps, wells, bore wells, lakes, etc. along the channel in both post-monsoon and pre-monsoon seasons and were subjected to analysis for determining physicochemical parameters like pH, Na, K, Ca, Mg, Cu, Zn, Cd, chloride, fluoride, sulfate, phosphate, electrical conductance, chemical oxygen demand, DO, etc. The chemical composition of groundwater of the study area was found to be strongly influenced by effective weathering and leaching action along with anthropogenic activities. The hydrochemical facies infer groundwater samples irrespective of seasons to be of Ca–Mg–SO4–Cl type. Furthermore, salinity, sodium adsorption ratio, percentage of sodium Na (%), residual sodium carbonate, piper trilinear diagrams, and Gibbs ratio suggest that 56.25% of samples were found to be unfit for irrigation.
Article
The present study aims to assess and understand the chemical characteristics of groundwater and geochemical processes occurring within the aquifer systems around chromite-mineralized areas in India. The water samples are collected from 33 groundwater sources are analyzed for physicochemical properties as well as major ion concentrations such as Ca2+, Mg2+, Na+, K+, $${\text{CO}}_{3}^{2 - }$$ , HCO3 −, Cl−, NO3 −, F− and $${\text{SO}}_{4}^{2 - }$$ in pre and post- monsoon. Alkali metal ions (Na+, K+) and alkaline earth metal ions (Ca2+, Mg2+) data of groundwater showed high concentration of Ca during pre-monsoon where as high concentration of Na in post-monsoon than other cations. The major hydro chemical facies identified as CaHCO3 type of water is predominant during pre-monsoon whereas the CaHCO3 and mixed CaNaHCO3 type of water in post-monsoon. The classification based on the total hardness reveals that a majority of groundwater samples fall in the hard to very hard category during the pre-monsoon season that is unfit for drinking. Anions such as bicarbonate 85 % and nitrate 18 % of the sample locations in pre- monsoon are exceed the WHO permissible limits, while during post- monsoon concentrations of bicarbonate decreased (70 %), nitrate increased (27 %). The suitability of water for irrigation by analyzing salinity hazard indicated by sodium adsorption ratio (SAR) and residual sodium carbonate (RSC). US Salinity diagram showed the majority of samples (>50 %) fall in the field of C3-S1, indicating water of high salinity and low sodium, which can be used for irrigation in almost all types of soils with attention.
Chapter
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The spring waters of the Sierra Nevada result from the attack of high CO2 soil waters on typical igneous rocks and hence can be regarded as nearly ideal samples of a major water type. Their compositions are consistent with a model in which the primary rock-forming silicates are altered in a closed system to soil minerals plus a solution in steady-state equilibrium with these minerals. Isolation of Sierra waters from the solid alteration products followed by isothermal evaporation in equilibrium with the earth's atmosphere should produce a highly alkaline Na-HCO3-CO3 water; a soda lake with calcium carbonate, magnesium hydroxysilicate, and amorphous silica as precipitates.
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The geochemical processes taking place along an 800 km flow line in the non-carbonate Continental Intercalaire aquifer (CI) aquifer in North Africa are described using chemical (major and trace element) and isotopic indicators. The aquifer is hydraulically continuous from the Atlas Mountains in Algeria to the Chotts of Tunisia and the geochemical evidence corroborates this. The highest discharge temperature is 73 °C but silica geothermometry indicates a maximum temperature of 94 °C at depth. Chloride concentrations increase from 200 to 800 mg l−1 and the Br/Cl ratios confirm the dissolution of non-marine evaporites or interstitial waters as the main source of salinity. Fluoride concentrations are low and are likely to be derived from rainfall, recording oscillations in source. Radiocarbon ages, except near outcrop, are at or near detection limits and the δ18O and δ2H values indicate a cooler recharge regime with rainfall having lower primary evaporation than today. This is shown by the fact that mean isotope ratios of CI waters are around 3‰ lighter than the present-day weighted mean value for rain. Major ion ratios and most trace elements indicate that despite the complex structure and stratigraphy, uniform evolution with continuous water-rock interaction takes place along the flow lines, which are only disturbed near the Tunisian Chotts by groundwater converging from additional flow lines. The ageing of the water can also be followed by the smooth increase in several indicator elements such as Li, K and Mn which are least affected by solubility controls. Similarly the influence of marine facies in the Tunisian sector may be recognised by the changing Mg/Ca and higher Br/Cl as well as trace element indicators. The groundwaters are oxidising up to 300 km from outcrop (dissolved O2 has persisted for at least 20 ka) and within this zone the concentrations of several elements forming oxy-anions, such as U and Cr, increase and NO3 remains conservative. Beyond 300 km from outcrop, the groundwaters are reducing and contain high Fe concentrations. The basin contains huge reserves of fresh/brackish waters but these need careful development due to the limiting high salinity and scaling tendency resulting from the high temperatures and mineral super-saturation caused during abstraction as well as high concentrations of some harmful elements such as Cr in the oxidising section.
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The hydrology of subarctic, discontinuous permafrost regions is sensitive to the effects of climatic warming, because pronounced changes in water storage and runoff pathways could occur with small additional ground heating. The objective of this study is to understand the hydrologic functions of unique land-cover types in this region (channel fens, flat bogs, and peat plateaus) using isotopic and chemical signatures of surface and subsurface water, as well as hydrometric measurements. The study was conducted in a 152-km2 basin of Scotty Creek, located in the central part of the Mckenzie River basin in northern Canada. The headwater of Scotty Creek, Goose Lake had a strongly enriched isotopic composition due to evaporation. The stream water composition changed downstream, as the lateral drainage from the active layer of peat plateaus contributed isotopically light and chemically dilute water to channel fens that are part of the drainage network. Flat bogs received drainage from peat plateau in addition to direct precipitation, and were internally drained or drained water to adjacent channel fens. Average evapotranspiration estimated from the chloride-balance method was 280–300 mm/yr, which was consistent with the hydrometric estimate (precipitation minus runoff) of 275 mm/yr indicating a potential applicability of this method to ungauged basins. Tracer-based hydrograph separation showed that the direct snowmelt contribution to spring runoff was less than half of total discharge, suggesting an importance of the water stored over winter in lakes and wetlands. The total amount of water stored over winter in the basin was estimated to be 140–240 mm, which was comparable to the average annual basin discharge (149 mm).
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The first eight chapters of this book treat the main chemical processes that affect groundwater composition. Examples are provided of how natural groundwaters have obtained their composition, and the effects of pollution are discussed. Under ideal field conditions a single chemical reaction may adequately describe the evolution of groundwater composition, but in general, the interplay of several processes must be considered. The remaining chapters present the systematics of transport in aquifers and how to couple transport to chemical reactions. It treats the basics of writing computer programs to calculate the combined effects of transport and chemical reactions. Applications of hydrogeochemical transport modelling of complex systems are demonstrated and geochemical approaches to aquifer clean-up schemes are evaluated. -from Authors
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Building on the success of its 1993 predecessor, this second edition of Geochemistry, Groundwater and Pollution has been thoroughly re-written, updated and extended to provide a complete and authoritative account of modern hydrogeochemistry. Offering a quantitative approach to the study of groundwater quality and the interaction of water, minerals, gases, pollutants and microbes, this book shows how physical and chemical theory can be applied to explain observed water qualities and variations over space and time. Integral to the presentation, geochemical modelling using PHREEQC code is demonstrated, with step-by-step instructions for calculating and simulating field and laboratory data. Numerous figures and tables illustrate the theory, while worked examples including calculations and theoretical explanations assist the reader in gaining a deeper understanding of the concepts involved. A crucial read for students of hydrogeology, geochemistry and civil engineering, professionals in the water sciences will also find inspiration in the practical examples and modeling templates. © 2005 C.A.J. Appelo & D. Postma, Amsterdam, The Netherlands and Ben Akkerman collection Stedelijk Museum, Amsterdam. All rights reserved.
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The hydraulic gradients and velocity of underground flow, the intensity of the water exchange with the earth's surface, the relation of the water-bearing bed to water (e.g., intensive flush, hampered flush, salt accumulation), the subsurface drainage conditions, the duration of time of the contact of water with the geological formations along with the chemical composition of rock material and the water which occurs in them and the structural features of the area, are considered as the chief factors governing the salinity variation of subterranean waters.
Article
450 samples of water have been collected from several crystalline massifs in Norway, France, Sahara, Senegal, Chad, Ivory Coast and Malagasy. The chemical composition of the waters is studied in relation with the dynamics of weathering. On the one hand the data of thermodynamics permit one to know the gibbsite, kaolinite and montmorillonite domains of stability. Thus one can point out which of these weathering minerals is in equilibrium with the waters draining the landscapes. On the other hand the ratios of the removal of basic cations to that of silica in waters permit one to discern the principal geochemical process of the present-day weathering in a region: allitization, monosiallitization or bisiallitization. The molecular ratiosSio2/(Na2O + K2O + CaO + + MgO)and(6Na2O+ 6K2O+ 2CaO − SiO2)(Na2O + K2O + CaO - SiO2)/(Na2O + K2O + CaO) in the solutions permit one to characterize these principal types of evolution. The results of thermodynamics and geochemical balances in the studied waters are in good agreement with the data about the evolution of weathering in the studied regions.
Article
Aquifers of the peninsulas of Florida and northern Yucatan are Tertiary marine carbonate formations showing many lithologic and faunal similarities. In addition, the tropical to subtropical climates of the two areas are similar, each having annual rainfall of about 1000 to 1500 mm. Despite similarities in these fundamental controls, contrasts in the hydrologic and geochemical systems are numerous and striking. For example, Florida has many rivers; Yucatan has none. Maximum thickness of fresh ground water in Florida is about 700 meters; in the Yucatan it is less than 70 meters. In Florida the gradient of the potentiometric surface averages about 1 meter per kilometer; in the Yucatan it is exceedingly low, averaging about 0.02 meter per kilometer. In Florida the chemical character of water changes systematically downgradient, owing to solution of minerals of the aquifer and corresponding increases in total dissolved solids, sulfate, calcium, and Mg-Ca ratio; in the Yucatan no downgradient change exists, and dominant processes controlling the chemical character of the water are solution of minerals and simple mixing of the fresh water and the body of salt water that underlies the peninsula at shallow depth. Hydrologic and chemical differences are caused in part by the lower altitude of the Yucatan plain. More important, however, these differences are due to the lack of an upper confining bed in Yucatan that is hydrologically equivalent to the Hawthorn Formation of Florida. The Hawthorn cover prevents recharge and confines the artesian water except where it is punctured by sinkholes, but sands and other unconsolidated sediments fill sinkholes and cavities and impede circulation. In the Yucatan the permeability of the entire section is so enormous that rainfall immediately infiltrates to the water table and then moves laterally to discharge areas along the coasts.
Article
Patterns and rates of chemical evolution of groundwater in a sandy silicate aquifer were determined by detailed analysis of groundwater velocity and chemistry along short (120 m) flow paths. Groundwater enters the aquifer mainly as seepage from a dilute lake and evolves chemically under open-COâ conditions for at least 8 years before discharging to another lake. Spatial trends in the aquifer are evident for calcium, magnesium, silicon, sodium, COâ, alkalinity, pH, temperature, and dissolved oxygen. The kinetics of silicate mineral dissolution regulates additions of calcium, magnesium, and alkalinity to the groundwater, causing them to increase steadily along flow paths at about 12 Î¼mol Lâ»Â¹ yrâ»Â¹ (Ca), 6 Î¼mol Lâ»Â¹ yrâ»Â¹ (Mg), and 39 Î¼eg Lâ»Â¹ yrâ»Â¹ (alkalinity) respectively, for at least 3-5 years. Silicon and sodium increase by 41 Î¼mol Lâ»Â¹ yrâ»Â¹ and 13 Î¼mol Lâ»Â¹ yrâ»Â¹ respectively for about 3 years, then level off as the groundwater approaches saturation with respect to kaolinite and smectite.
Article
Insights into the chemical and Hydrogeologie history of spring waters in carbonate rocks can be gained from a study of the chemical quality of such waters and of the waters which feed springs. The median Ca2+/Mg2+ ratio was 3.4 in 29 spring waters from folded and faulted carbonate rocks near State College, Pennsylvania, indicating ground-water flow predominantly in limestone. The mean dissolved oxygen content was 7.7 mg/1 or 71% of saturation consistent with subsurface flow chiefly under water table conditions. Most of the dissolved solids (as specific conductance) including pollutants such as Cl and NO3 were added to spring waters during ground-water flow. Specific conductances ranged from 180 to 476 micromhos, with a mean of 347 micromhos. CO2 pressures were from 10−1.9 to 10−2.6 atm with a mean of 10−2.2. atm. The CO2, which is chiefly introduced as gas by downward diffusion from the soil zone, gives spring waters the capacity to hold about 3 times more hardness and alkalinity than streams in equilibrium with the atmosphere. However, all spring waters were undersaturated with respect to calcite and dolomite because of their short residence times as ground water. Dye tracing of ground-water feeding springs in two drainage basins gave residence times of 2–6 days for subsurface flows of about 4,000 feet. The specific conductance and carbonate saturation data indicate that ground-water residence times of the 29 spring waters average somewhat longer than 2–6 days.
Article
Hydrochemical and stable isotope (18O and 2H) analyses of groundwater samples were used to establish the hydrochemistry of groundwater in the Ankobra Basin. The groundwater was generally mildly acidic, low in conductivity and undersaturated with respect to carbonate phases. Major ions except bicarbonate were low and dissolved silica was moderately high. Silicate minerals weathering is probably the main process through which major ions enter the groundwater. Groundwater samples clustered tightly along the Global Meteoric Water Line suggesting integrative, smooth and rapid recharge from meteoric origin. The majority of the boreholes and a few hand dug wells cluster towards the Ca–Mg–HCO3 dominant section of the phase diagram, in conformity with the active recharge and short residence time shown by the isotope data. Aluminium, arsenic, manganese, iron and mercury were the only trace metals analysed with concentrations significantly above their respective detection limits. Approximately 20%, 5%, 40% and 25% respectively of boreholes had aluminium, arsenic, iron and manganese concentrations exceeding the respective WHO maximum acceptable limits for drinking water. The relatively large percentage of boreholes with high concentration of aluminium reflects the acidic nature of the groundwater.
Article
Chemical and isotopic analyses are used to characterize and identify the relevant water-rock interactions, which are responsible for the poor groundwater quality in the Accra Plains. Four main water types are identified. Processes that singly or in combination influence the chemical composition of each water type include halite dissolution carbonate dissolution and precipitation, seawater intrusion, cation exchange, evaporative concentration of solutes and aluminosilicates dissolution. These processes contribute considerably to the concentration of major ions in the groundwater. Stable isotope contents of the groundwater suggest mainly direct integrative recharge. A few samples plot along the meteoric-seawater mix line which is coincidentally the evaporative line. The Cl−/Br− ratios of some of these are close to 300 confirming marine origin, others probably concentrated by evaporation have their Cl−/Br− ratios significantly lower than 300. Groundwater is qualitatively good for drinking purposes only along the foothills of the Akwapim Togoland ranges.
Article
The pH-dependence of far from equilibrium steady-state dissolution rates of silicates can be understood by considering the detachment rates of their oxide components through surface protonation-deprotonation reactions. At high pH, where Si surface sites are deprotonated and therefore carry negative charge, detachment of silicon appears to control overall silicate dissolution rates. At low pH, near the zero point of charge of SiO2 (where surface charge is dominated by the other oxide components), detachment of the non-silicon structure-forming oxides apparently controls dissolution rates of multi-oxide silicates. Correlations between metal-oxygen site potentials and pH-dependent surface detachment reactions permit estimation of dissolution rates of a large number of silicates from pH 5 to pH 12.
Article
The field pH and content of Ca2+, Mg2+, HCO3−, dissolved oxygen and other aqueous species have been measured in 29 spring waters and 29 well waters in folded and faulted Paleozoic carbonate rocks near State College, Pennsylvania. Most of the springs issue from limestone; most of the well waters are pumped from dolomite. Average specific conductances of the spring and well waters were 347 and 499 μΩ−1, respectively, with polluted well waters having conductances as high as 945 μΩ−1. Molar ratios as low as 0.6 in the well waters have resulted from incongruent solution of dolomite. Theoretical treatment of relationships between PCO2, pH and HCO3− content shows that solution of calcite or dolomite by undersaturated waters leads to increases in both pH and HCO3− content. This relation is approximately obeyed by the spring waters at an average CO2 pressure of 10−2.2 atm. In contrast, solution or precipitation of carbonates by waters near saturation with respect to them, results in inverse relationships of pH and HCO3−; a behavior closely obeyed by the well waters which have CO2 pressures up to 10−1.6 atm. Computer calculation of ground water saturation with calcite and dolomite at ground water temperatures (8–14°C) was made using remeasured solubility product data for calcite, and considering the effect of CaSO40, MgSO40 and MgHCO3+ ion pairs. Within the uncertainty of the chemical analyses and thermochemical data, 12 well waters and 3 spring waters were saturated with calcite, whereas 7 well waters and 3 spring waters were saturated with dolomite. None of the ground waters significantly exceeded saturation with respect to either carbonate.
Article
The chemical composition of 185 groundwater samples collected from two catchments in the extreme NE Norway and NW Russia over the period April 1994 to November 1995 is reported in terms of Ag, Al, As, B, Ba, Be, Bi, Br, Ca, Cd, Cl, Co, Cr, Cu, F, Fe, K, Li, Mg, Mn, Mo, Na, Ni, NO3, P, Pb, PO4,Rb, S, Sb, Se, Si, SO4, Sr, Th, Ti, Tl, U, V and Zn concentrations (as determined by ICP-MS, ICP-AES and IC), pH and electrical conductance. One catchment (C2) is located in Russia 5 km downwind of the nickel—copper ore smelting industry in Monchegorsk, which is a major SO2 and trace metal emission source, the other (C5) is located in Norway 30 km off-wind from the nickel-copper ore smelter in Nikel and 52 km off-wind from the nickel—copper ore roasting plant of Zapoljarniy, which are also significant emitters of inorganic atmospheric pollutants.Groundwater chemistry mostly reflects the mineralogical composition of the gabbro aquifer in C2 and the Quaternary deposits in C5, although groundwater in C2 also shows signs of incipient contamination from surface waters (heavy metals, sulphate, chloride). Groundwater in C2 appears to have been acidified by S-compounds emitted from Monchegorsk, but the groundwater's capacity to neutralise incoming acidity has not been exhausted. In C5, groundwater has not been acidified to any extent and has a high acid neutralising capacity. This study demonstrates that the geological substrate of a catchment is a fundamental control on how groundwater responds to atmospheric pollution, even if the latter is severe.
Environmental isotope study of groundwater in crystalline rocks of the Accra Plains
• T T Akiti
• TT Akiti
Akiti, T. T. (1986). Environmental isotope study of groundwater in crystalline rocks of the Accra Plains. In 4th Working Meeting Isotopes in Nature. Leipzig. September 1986. Proceedings of an advisory group meeting. Vienna: IAEA.
A new geography of Ghana
• K B Dickson
• G Benneh
• KB Dickson
Dickson, K. B., & Benneh, G. (1980). A new geography of Ghana. London: Longmans Group Limited.
Practical guide for groundwater sampling. Illinois State Water Survey ISWS Contract Report 374 Control of sil-ica dissolution rates in neutral and basic solutions at 250C
• M Barcelona
• J P Gibb
• J A Heldrich
• E E Garske
• J V Walther
Barcelona, M., Gibb, J. P., Heldrich, J. A., & Garske, E. E. (1985). Practical guide for groundwater sampling. Illinois State Water Survey ISWS Contract Report 374. Brady, P. V., & Walther, J. V. (1989). Control of sil-ica dissolution rates in neutral and basic solutions at 250C. Geochimica et Cosmochimica Acta, 53, 2823– 2830. doi:10.1016/0016-7037(89)90160-9.
Arid zone hydrology recent develop-ments Vulnerability of shal-low groundwater quality due to natural geochemical environment. Health problems related to groundwater in Obuasi and Bolgatanga Areas
• Am
• P L Smedley
• W M Edmunds
• J M West
• S J Gardner
Am. Geophysical Union. Trans. Schoeller, H. (1959). Arid zone hydrology recent develop-ments. UNESCO Rev. Reicardi, 12. Smedley, P. L., Edmunds, W. M., West, J. M., Gardner, S. J., & Pelig-ba, K. B. (1995). Vulnerability of shal-low groundwater quality due to natural geochemical environment. Health problems related to groundwater in Obuasi and Bolgatanga Areas, Ghana. ODA/BGS Technology Development and Research Program, Report 92/5.
Chemical analysis of groundwater. Geochemistry, groundwater and pol-lution Comparison of chemical hydrogeology of the carbonate peninsu-las of Florida and Yacatan
• C A J Postma
, C. A. J., & Postma, D. (1999). Chemical analysis of groundwater. Geochemistry, groundwater and pol-lution. Rotterdam: Balkema. Back, W., & Hanshaw, B. B. (1970). Comparison of chemical hydrogeology of the carbonate peninsu-las of Florida and Yacatan. Journal of Hydrology (Amsterdam), 10, 330–368. doi:10.1016/0022-1694(70) 90222-2.
Etude geochimique et isotopique de quelques aquifere du Ghana
• T T Akiti
Akiti, T. T. (1980). Etude geochimique et isotopique de quelques aquifere du Ghana. PhD thesis, Universite de Paris-Sud.
Guidelines and techniques for obtaining water samples that accurately represent the water quality for an aquifer
• H C Claasen
Claasen, H. C. (1982). Guidelines and techniques for obtaining water samples that accurately represent the water quality for an aquifer. U.S. Geological Survey Open File Report 82-1024, 49 pp.
Reverse ion exchange in a deeply weathered porphyritic dacite fractured aquifer system
• J Jankowski
• R I Acworth
• S Shekarforoush
Jankowski, J., Acworth, R. I., & Shekarforoush, S. (1998). Reverse ion exchange in a deeply weathered porphyritic dacite fractured aquifer system, Yass, New South Wales, Australia. In G. B. Arehart, & J. R. Hulston (Eds.), Proc. 9th Int. symp. Water-Rock Interaction Taupo, New Zealand (pp. 243-246). Rotterdam: Balkema.
The mineral and rock resource of Ghana. Rottendam: Balkema
• G O Kesse
• GO Kesse
Kesse, G. O. (1985). The mineral and rock resource of Ghana. Rottendam: Balkema.
Chemical weathering of ore and host rock in six Norwegian sulphide mines
• R Nilsen
• G Grammeltvedt
Nilsen, R., & Grammeltvedt, G. (1993). Chemical weathering of ore and host rock in six Norwegian sulphide mines. Norges geologiske undersokelse report 93. 037, Ngu, Trondheim, Norway.
Phreeqc for windows version 1. 4. 07. A hydrogeochemical transport model
• D L Parkhurst
• C A J Appelo
Parkhurst, D. L., & Appelo, C. A. J. (1999). Phreeqc for windows version 1. 4. 07. A hydrogeochemical transport model. U.S. Geological Survey Software.
Information building block. Ghana water management study. Unpublished consultancy report for the Ministry of Works and Housing
• Nii Consult
Vulnerability of shallow groundwater quality due to natural geochemical environment. Health problems related to groundwater in Obuasi and Bolgatanga Areas, Ghana. ODA/BGS Technology Development and Research Program
• P L Smedley
• W M Edmunds
• J M West
• S J Gardner
• K B Pelig-Ba
Smedley, P. L., Edmunds, W. M., West, J. M., Gardner, S. J., & Pelig-ba, K. B. (1995). Vulnerability of shallow groundwater quality due to natural geochemical environment. Health problems related to groundwater in Obuasi and Bolgatanga Areas, Ghana. ODA/BGS Technology Development and Research Program, Report 92/5.
Geohydrological and mineralization studies with environmental isotopes in a large Kalahari ranching development
• B T Verhagen
• C Marobela
• G Sawula
• B Kgarebe
Verhagen, B. T., Marobela, C., Sawula, G., & Kgarebe, B. (1995). Geohydrological and mineralization studies with environmental isotopes in a large Kalahari ranching development (pp. 91-95). IAEA-SM 366/41, Vienna.
Practical guide for groundwater sampling
• M Barcelona
• J P Gibb
• J A Heldrich
• E E Garske
Barcelona, M., Gibb, J. P., Heldrich, J. A., & Garske, E. E. (1985). Practical guide for groundwater sampling. Illinois State Water Survey ISWS Contract Report 374.
Unpublished consultancy report for the Ministry of Works and Housing
• Nii Consult
Nii Consult (1998). Information building block. Ghana water management study. Unpublished consultancy report for the Ministry of Works and Housing, Ghana, /DANIDA/World Bank.
Guidelines for drinking water quality. Revision of the 1984 guidelines. Final task group meeting
World Health Organisation (WHO) (1993). Guidelines for drinking water quality. Revision of the 1984 guidelines. Final task group meeting. Geneva 21-25 September 1992W.
Groundwater assessment: An element of integrated water resources management-the case study of Densu River Basin
• Wri
WRI (2003). Groundwater assessment: An element of integrated water resources management-the case study of Densu River Basin. WRI/CSIR, Accra.
Report on borehole drilling and installation of drivers for groundwater monitoring in the Densu River Basin
• Wri
WRI (2005). Report on borehole drilling and installation of drivers for groundwater monitoring in the Densu River Basin. WRI/CSIR, Accra.