Fluoride in groundwater in the Bongo District, Ghana: an assessment, health impact and possible mitigation strategies (original) (raw)
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ABSTRACT Groundwater is the most appropriate portable and widely used source of drinking water for many rural communities in Ghana and its quality has special health significance and needs great attention of all concerned since it is the major alternate source of domestic, industrial and drinking water supply in Ghanaian communities. Fluoride is a common constituent of groundwater and its sources are connected to various types of rocks and to volcanic activity, Agricultural (use of phosphate fertilizers) and industrial activities. Fluoride contamination in drinking water is a public health problem in many areas around the world. Chronic ingestion of high doses has been linked to the development of dental fluorosis, abnormal thyroid function and other hormonal disturbances and in extreme cases, skeletal fluorosis. High doses have also been linked to cancer (Marshall, 1990) and (Ilamiiton, 1992). The study was carried out to evaluate the geologic controls on fluoride concentrations in groundwater from northern and southern Ghana on the West African Craton. Groundwater from active pumping wells and rock samples from outcrops were collected from various communities from northern and southern Ghana for fluoride and petrological (thin section) analysis. The fluoride concentration in groundwater in some communities of northern Ghana was recorded up to 4.0 mg/l and the overall water quality found was unsatisfactory with respect to fluoride for drinking purposes without any treatment and 0.8mg/l for the south which is considered to be good for drinking. The petro logical analysis indicates that the geological source of fluoride in groundwater is related to leaching of minerals from rocks thus metamorphic (gneissic) rocks and granitoids (Bongo granites) which are rich in mica, quartz and sericite as well as microcline. Among the fluoride-bearing minerals, only biotite was abundant in rock samples. There was a Positive correlation between fluoride concentration in the groundwater and the percentage of biotite composition in rock samples. Therefore, the high fluoride concentrations in the groundwater are more likely to result from the dissolution of biotite (K (Mg,Fe)3AlSi3O10(F,OH)2) which contain fluorine at the OH− sites of the octahedral sheet.
Removal of fluoride from rural drinking water sources using geomaterials from Ghana
2008
This paper presents preliminary findings on the fluoride removal capability of some Ghanaian geomaterials and their potentials of being used to develop, design replicable easy-to-manage rural community based fluoride removal system. Batch experiments were performed on geomaterials (laterite and bauxite tailings) with raw fluoride-contaminated water (10.31 mg/l) from a borehole to determine their potentiality of removing excess fluoride from rural drinking water supplies. The raw bauxite tailings showed the higher removal capacity. Further experiments were conducted using heat-treated bauxite tailings. The results indicate that optimum fluoride removal is attained when the bauxite is heated to 600oC but removal capacity decreases with increased heating temperature. XRF analyses to determine chemical composition indicated Al2O3, Fe2O3 and SiO2 (silica) to be the most dominant compounds in that order.
Fluoride content in water has received a world-wide attention due to its importance to health. This study attempts to trace the factors responsible for low fluoride levels in the aquifers of the Jos Younger Granites despite the high fluorine content in the rocks. A total of 41groundwater samples (1 mining pond, 2 hand pumps and 38 hand dug wells), 7 rock samples from the various lithological units, and 13 soil sections from two exposed locations were collected and analyzed for their fluorine content. Analysis of major cations was carried out using ICP-OES; the anions were analyzed using the UV multi-ion parameter and bicarbonates by titration method. Fluoride in underground water was determined by multi-ion parameter. Fluorine in rocks and soil were analyzed by the fusion method. The rock samples show variations in their fluorine content (Jos – Bukuru Biotite Granite 6,231, aplo-pegmatic granite-gneiss (basement rock) 4,864, Quartz-pyroxenes-fayalite porphyry 1,280, Dilimi-Biotite Granite 258 and Ngeil Biotite Granite-162 ppm). The soil sections from different locations also show variations of fluorine with depth of sampling. Cumulatively, the fluorine content in the sections and fluoride content in water do not correlate with fluorine in rock in the rock units. The low content in the two media, indicate that: 1. bulk fluorine have not been released from minerals in the host rocks and those retained in soils have not been mobilized to the groundwater. 2. Fluorine have formed complexes with other ions and occurring in compound form rather than ionic form. Apart from low fluoride in about 70% of the water samples all other parameters are within the WHO recommended limit for house hold uses. Although there are no records on the effect of low consumption of fluoride in water, inferences from the data show that most areas with low fluoride level should have dental caries.
A Review of Fluoride Removal from Groundwater
Periodica Polytechnica Chemical Engineering
Most of the arid and semiarid zones of the Indian subcontinent are seriously affected by the fluorosis problem due to high concentration of the fluoride in ground water. Due to leaching of fluoride from the fluoride bearing rocks, the groundwater gets contaminated with fluoride. The different techniques for fluoride removal namely, the Activated alumina, the Nalgonda technique, bone charcoal, contact precipitation, electro-dialysis, reverse osmosis, ion-exchange, clay column, bio-adsorbents and MgO are discussed in detail. Their advantages and disadvantages together with the applicability in actual use also been discussed in the paper.
Sustainable Water Resources and Management
This study was conducted to understand the hydrochemistry of groundwater in the Bongo district and unravel the source of fluoride in the groundwater using an integrated hydrochemical analysis and multivariate geostatistical analysis. A total of thirty (30) borehole water samples were collected in various communities in the district during the dry season. The district is dominated by Upper Birimian (Paleoproterozoic) metavolcanics and granitoids known as the Bongo granitoids. Hydrochemical facies identified in the area include Ca–Na–HCO3 (70%) and Ca–Mg–HCO3 (30%) water types. The Ca–Na–HCO3 water types are hosted in fractured bedrocks of the Upper Birimian metavolcanics and the K-feldspar rich Bongo granitoids, whereas the Ca–Mg–HCO3 water types are within the Upper Birimian volcanic/metavolcanic sequences. All the hydrochemical parameters show acceptable concentrations for drinking purposes except fluoride (1.71–4.0 mg/L). The high fluoride concentrations in the groundwater are largely due to intense dissolution of the Bongo granitoids, which contain biotite and muscovite as the dominant fluoride-bearing minerals. The pH, Ca²⁺, SO4²⁻, HCO3⁻ and CO3²⁻ concentrations have weak positive correlations with F⁻ concentrations of the groundwater implying some dependent relationship and different source for the fluoride. Principal component analysis performed on the hydrochemical data resulted in three principal components (PCs), which explain 76.251% of the total variance. The three PCs represent the dominant processes influencing the groundwater chemistry, which include water–rock interaction, mineral dissolution, and ion exchange reactions, respectively, with water–rock interaction as the most dominant process. However, anthropogenic sources such as the use of phosphate fertilizers cannot be precluded from contributing to the groundwater fluoride contamination.
Fluoride in Groundwater: Causes, Implications and Mitigation Measures
Groundwater is the major source for various purposes in most parts of the world. Presence of low or high concentration of certain ions is a major issue as they make the groundwater unsuitable for various purposes. Fluoride is one such ion that causes health problems in people living in more than 25 nations around the world. Fluoride concentration of atleast 0.6 mg/l is required for human consumption as it will help to have stronger teeth and bones. Consumption of water with fluoride concentration above 1.5 mg/l results in acute to chronic dental fluorosis where the tooth become coloured from yellow to brown. Skeletal fluorosis which causes weakness and bending of the bones also results due to long term consumption of water containing high fluoride. Presence of low or high concentration of fluoride in groundwater is because of natural or anthropogenic causes or a combination of both. Natural sources are associated to the geological conditions of an area. Several rocks have fluoride bearing minerals like apatite, fluorite, biotite and hornblende. The weathering of these rocks and infiltration of rainfall through it increases fluoride concentration in groundwater. Fluoride which is present in high concentration in volcanic ash is readily soluble in water and forms another natural source. Anthropogenic sources of fluoride include agricultural fertilisers and combustion of coal. Phosphate fertilisers contribute to fluoride in irrigation lands. Coal which is a potential source of fluoride is used for combustion in various industries and in brick kilns. The aerial emission of fluoride in gaseous form during these activities reaches the surface by fall out of particulate fluorides and during rainfall they percolate with the rainwater thus reaching the groundwater table. Also the improper disposal of fly ash on ground surface contributes to fluoride in groundwater. Since ingestion of high fluoride has a long term effect on human health it is essential to monitor its concentration in groundwater used for drinking periodically and take steps to bring them within the permissible range of 0.6 to 1.5 mg/l. There are several methods available for the removal of fluoride from groundwater which is insitu or exsitu. To dilute the groundwater contaminated with fluoride, artificial recharging structures can be built in suitable places which will decrease its concentration. Rainwater harvesting through existing wells also will prove effective to reduce the groundwater fluoride concentration. Exsitu methods which are conventional treatment methods like adsorption, ion exchange, reverse osmosis, electrodialysis, coagulation and precipitation etc can be practiced at community level or at households to reduce fluoride concentration before ingestion. But the choice of each method depends on the local conditions of the region such as the quality of groundwater and the source of contamination whether it is natural or anthropogenic. Fluoride contamination being a prominent and widespread problem in several parts of the world and as causes for this are mostly natural and unpreventable, educating the people and defluorinating the groundwater before consumption are essential for a healthy world.
2021
In Saboba District of the Northern region of Ghana, many a people depend on boreholes as their main source of water for drinking and other domestic purposes in the communities. An assessment and evaluation of the quality and suitability of borehole water sources for drinking was conducted or carried out by determining levels of fluorides and other physicochemical parameters namely pH, salinity, Total Dissolved Solids (TDS), fluoride concentration, electrical conductivity and turbidity. Samples were taken from ten different boreholes within the Saboba township. The analytical results showed that, all the investigated physicochemical parameters of water samples were within the permissible limits for drinking water as suggested by World Health Organization (WHO). A Palin test for fluoride was used for the determination of the concentration of fluoride in the water samples. The mean fluoride content was 1.08mg/L. The fluoride concentration of all the samples were within the maximum standard limit of 1.50mg/L set by World Health Organization specification for drinking water.
Hydrogeochemical appraisal of fluoride in groundwater of Langtang area, Plateau State, Nigeria
Global Journal of Geological Sciences, 2016
Consumption of high fluoride in groundwater of Langtang area, manifest in the inhabitants of the area in form of dental fluorosis and skeletal fluorosis in older group. The aim of this study was to appraise the hydrogeochemistry of fluoride in the groundwaters of Langtang area. Thirty seven surface and groundwater samples and nine rock samples were collected in Langtang area for geochemical analysis. The Inductively Coupled Plasma Emission Spectrometry (ICPOES) was used to detect cations. The anions (Cl-, SO 4 = and Br-) were determine by Ion Chromatography method. Fluoride was determined by the Specific Ion Electrode and bicarbonate was determined by titration. Major oxides, trace elements and rare earth elements for the rock samples were determined by the XRF method and fluorine by the Fusion method. Polished thin sections for rocks were prepared and studied. Geochemical results from analysis of the samples (rock and water) show that four major rock units make up the geology of the area; coarse porphyritic biotite granite, migmatite, rhyolite and riebeckite granites, the minor ones are pegmatite, trachyte, aplite and fine to medium grained biotite granites. The rhyolite, the riebeckite granites and trachyte have the highest level of fluorine content in the area (1,470, 1000, 900 and 800 ppm) respectively. The fluorine mineral (Fluorite) crystallized in the late stage of the magma as replacement of Fe/Mg mineral probably hornblende or biotite. Fluorine is leached into the groundwater from the rhyolite under the slightly alkaline (Ca-Mg-HCO 3 evolving Na-HCO 3) water in the area. The two major groundwater types (Ca-Mg-HCO 3 and Na-HCO 3) in the area have good relationship with content of fluoride in water. Although, the riebeckite granites have high fluorine content, contribution of fluoride from them is towards the southern portion of the map, owing to the groundwater flow direction. The different water sources in the area do not show variation in content of fluoride in water. However, groundwater barriers (dykes) may be responsible for some area having low fluoride (<1.5 mg/l) content. The consumption of high content of fluoride in the area has resulted in severe dental fluorosis in both children and youths and bowing of legs (Genu Valgum) in children with no discrimination between the sexes.
West African Journal of Applied Ecology, 2017
Fluoride contamination of groundwater within the Savelugu-Nanton District was assessed using hydrogeochemical framework and multivariate statistical approach. Eighty-one (No) boreholes were sampled for quality assessment in May and June 2008. The main objective of this study was to assess the fluoride levels in groundwater and delineate areas of low fluoride and high fluoride within the district. The study show that, 41.9% of the boreholes are within the safe limits of 0.5-1.5 mg/L of fluoride for the protection of bones and teeth, 43.2% of the boreholes have fluoride levels below the lower safe limit (< 0.5 mg/L) and therefore vulnerable to dental caries, 10.8% of the boreholes have fluoride levels between 1.5 and 3.0 mg/L and therefore vulnerable to dental fluorosis and 4.1% of the boreholes have fluoride levels between 3.0 and 10 mg/L and therefore vulnerable to skeletal fluorosis. The results further show that, 14.9% of groundwater requires defluoridation, while, 43.2% of groundwater requires fluoride addition to the groundwaters. PCA using Varimax with Kaiser Normalization results in the extraction of three main principal components which delineates the factors that influence the principal components of the physico-chemical parameters. The three principal components have accounted for approximately 83% of the total variance. Component 1 delineates the main natural processes through which groundwater within the basin acquire its chemical characteristics. Component 2 delineates pollution sources principally fluoride and nitrate. Component 3 suggests mineralogical influence of fluoride with some major ions on the chemistry of groundwater. The loadings and score plots of the first two PCs which explains 71.52% of the total variance show grouping pattern which indicates the strength of the mutual relation amongst the hydrochemical variables. Biological defluoridation though not very well understood, is recommended as a best alternative to the conventional methods of defluoridation especially in developing countries due to its cost effectiveness.
Occurrence of Fluoride in the Groundwater of Kaltungo Area and Environs, North Eastern Nigeria
Journal of Geoscience and Environment Protection, 2019
The aim of the study is to assess the occurrence of fluoride in the groundwater of Kaltungo area and environs. Consumption of high fluoride waters clearly manifests in the majority inhabitant of the area in form of dental fluorosis especially in the majority of the populace. Thirty groundwater samples were collected from hand-dug wells and boreholes using standard method and were analyzed to determine the fluoride level. The results revealed that the Fluoride in the waters ranges from 0.8 to 1.94 mg/l with a mean value of 1.65 mg/l. No clear variations in fluoride content have been observed in both the borehole samples and those from the hand-dug wells. Ca-Mg-HCO 3 and Ca-Mg-Cl are the two major water types obtained in the area, which have a good association with fluoride. Negative correlation is observed between fluoride and temperature, fluoride and magnesium, fluoride and potassium and poor correlation is observed between fluoride and chloride, fluoride and nitrate, fluoride and phosphates which rules out the possibility of anthropogenic source of the fluoride in the waters. Positive correlation between fluoride and iron, indicates that the presence of fluoride in the water is as a result of dissolution of biotite within the host rock (Basalt).