Browsing by Author "Tay, C.K."
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Item Human Exposure Risks Assessment of Heavy Metals in Groundwater within the Amansie and Adansi Districts in Ghana using Pollution Evaluation Indices(West African Journal of Applied Ecology, 2019) Doamekpor, L.K.; Tay, C.K.; Dorleku, M.Non-carcinogenic risk assessment was done using Hazard Quotient (HQing/derm) and Hazard Index (HIing/derm) following USEPA methodology for a total of 59 boreholes and 12 hand dug wells sampled between July and October 2012. The objective was to assess the potential human health risks caused by exposure to non-carcinogenic heavy metals and estimate the potential environmental risk exposure in order to ensure the health safety of consumers within the Amansie and Adansi Districts. The results shows that, the heavy metal abundance in groundwater within the districts is in the order: Fe > Mn > As > Zn > Cu = Pb > Cd > Hg, for borehole water and Fe > As > Mn > Zn > Cu > Cd > Pb > Hg, for well water. The percentage contributions are: Fe (60%), Mn (20%), As (7%), Zn (5%), Cu (4%), Pb (4%), Cd (0%) and Hg (0%). The results also show that, the potential non-carcinogenic risks of exposure (HQing/derm) posed by Fe, Mn, Cd, Cu, Zn, Pb, As and Hg within a single route of exposure via ingestion or dermal contact is 3.30 x 10-2, 1.40 x 10-1, 5.00 x 10-4, 3.70 x 10-2, 3.00 x 10-1, 3.60 x 10-2, 3.00 x 10-4 and 3.00 x 10-4 respectively for both adults and children, suggesting a decreasing order of Zn > Mn > Cu > Pb > Fe > Cd > As = Hg, for borehole water, and Zn > Mn > Cu > Fe > Cd > As = Hg, for well water. The concerns for potential human health risks caused by exposure to non-carcinogenic heavy metals for Fe, Mn, Cd, Cu,Zn, Pb, As, and Hg are: 6.0 x10-2, 2.56 x 10-1, 9.15 x 10-4, 6.77 x 10-2, 5.49 x 10-1, 6.59 x 10-2, 5.49 x 10-4, 5.49 x 10-4 for boreholes, and 6.46 x 10-2, 2.74 x 10-1, 9.79 x10-4, 7.25 x 10-2, 5.88 x 10-1, 5.88 x 10-4, 5.88 x 10-4 for well water, suggesting that there is no concern for potential human health risks caused by exposure to non-carcinogenic toxic heavy metals in groundwater within the Districts (i.e HQ/HI <1). The study further show that, the risk index factor (Ri) for heavy metals was in the order: Hg > As > Cd > Pb > Cu > Zn, for borehole water, and As > Cd > Cu > Zn for well water, suggesting that, groundwater within the Districts is potentially threatened by anthropogenic activities primarily, mining activities where, chemicals such as arsenic (As) and mercury (Hg) are used to recover gold from its amalgam. Based on the classification of environmental risk using comprehensive risk factor (CRI), borehole water within the districts could be classified as very high risk, while, well water could be classified as high risk. Generally, the main environmental heavy metals that poses pollution risk in groundwater within the Districts were Hg, As and Cd and contributed mostly to the Risk index factor (Ri).Item Hydrochemical appraisal of groundwater evolution within the Lower Pra Basin, Ghana: a hierarchical cluster analysis (HCA) approach(Environmental Earth Sciences, 2014-08) Tay, C.K.; Hayford, E.; Hodgson, I.O.; Kortatsi, B.K.The most relevant controls on groundwater quality within the Lower Pra Basin in Ghana were assessed using Q-mode hierarchical cluster analysis (HCA). The objective was to determine the chemical characteristics of the various water groups and subgroups responsible for the groundwater evolution and identify the groundwater recharge and discharge zones within the basin. The Q-mode HCA have characterized hydrochemical data from a total of sixty-eight (68) boreholes and two (2) streams within the basin into four (4) water groups and five (5) subgroups. Results showed that, Group 1 waters had the lowest mean pH (5.6 pH units) with EC and TDS in the range 64.9–295 µS/cm and 32.5–162.0 mg/L respectively, while, Group 4 waters had intermediary mean pH (6.3 pH units) with highest EC and TDS in the range 1,221.2–1,601.0 µS/cm and 661–691 mg/L respectively. Two main water types—the Na–HCO3 and Ca–Mg–HCO3 with Na–Cl and Ca–Mg–Cl as minor water types have also been delineated. Results also showed that, Groups 1 and 2 waters both represents transition zones between Ca–Mg–HCO3/Na–HCO3 and Na–Cl/Ca–Mg–Cl type waters and therefore, can be regarded as transition zones between naturally circulating groundwaters which have not undergone pronounced water–rock interaction/aggressive recharging alkali carbonate waters and limited recharging local rain/permanent hard water. Thus, groundwater within the basin perhaps evolves from fresh- Ca–Mg–HCO3/Na–HCO3 type waters to permanent hard- Ca–Mg–Cl type waters and limited recharging local rain- Na–Cl type waters along its flow paths principally due to ion-exchange reactions. However, Zion Camp areas may be serving as discharge areas to groundwater within the basin. © 2014, Springer-Verlag Berlin Heidelberg.Item Hydrochemical Evolution of Ground and Surface Water within the Amansie and Adansi Districts of the Ashanti Region, Ghana(West African Journal of Applied Ecology, 2018-07) Tay, C.K.; Dorleku, M.; Koranteng, S.S.Source-rock deductions of major ions and saturation states of minerals in groundwater were employed to determine the origin of dissolved ions and the thermodynamic controls on the groundwater composition respectively in groundwater within the Amansie and Adansi Districts. The main objective of this study is to characterize groundwater and delineate soil-water-rock interactions responsible for the chemical evolution of groundwater within the districts. Fifty-nine boreholes, twelve wells and two stream samples were collected for quality assessment. Results show that, silicate weathering and ion-exchange reactions are the major processes influencing groundwater chemistry within the Districts. Results also show that groundwater within the districts is strongly to moderately acidic as, 62 % of the groundwaters has pH that range 3.6-6.0. Acidity in ground and surface water within the districts is attributable predominantly to natural processes than mining activities; however, the groundwaters still have the potential to neutralize acids due to the presence of silicates/aluminosilicates. The waters are fresh (EC< 500 μS/cm) with conductivity values which ranged 22.8-473 μS/cm, and a mean value of 172.9 μS/cm. TDS of the groundwaters ranged 14.9-309.8 mg/L with a mean value of 112.6 mg/L. The relative abundance of cations and anions are in the order: Ca 2+ > Na + > Mg 2+ > K + and HCO 3-> Cl-> SO 4 2-respectively. The states of saturation of the groundwaters with respect to major minerals using hydrogeochemical transport model Phreeqc for Windows suggest that, anhydrite and gypsum are subsaturated and indicates that, groundwater within the districts originates from a formation with insufficient amount of these minerals in solution or short residence time of these minerals with groundwater within the districts.Two principal hydrochemical water types; Ca-Mg-HCO 3 and Na-Cl have been delineated, with Ca-Mg-SO 4 , Na-Mg-Ca-HCO 3 and Na-Cl-SO 4 as minor water types. Groundwater within the districts principally evolves from fresh Ca-Mg-HCO 3 type water into Na-HCO 3 type water into Ca-Mg-Cl type water into Na-Cl type water along its flow path due to ion-exchange reactions and therefore, largely characterized by recharge processes through mixing with waters of geochemically different ionic signatures.Item Hydrogeochemical evaluation of groundwater in the lower Offin basin, Ghana(Environmental Geology, 2008-02) Kortatsi, B.K.; Tay, C.K.; Anornu, G.; Hayford, E.; Dartey, G.A.Alumino-silicate mineral dissolution, cation exchange, reductive dissolution of hematite and goethite, oxidation of pyrite and arsenopyrite are processes that influence groundwater quality in the Offin Basin. The main aim of this study was to characterise groundwater and delineate relevant water-rock interactions that control the evolution of water quality in Offin Basin, a major gold mining area in Ghana. Boreholes, dug wells, springs and mine drainage samples were analysed for major ions, minor and trace elements. Major ion study results show that the groundwater is, principally, Ca-Mg-HCO3 or Na-Mg-Ca-HCO3 in character, mildly acidic and low in conductivity. Groundwater acidification is principally due to natural biogeochemical processes. Though acidic, the groundwater has positive acid neutralising potential provided by the dissolution of alumino-silicates and mafic rocks. Trace elements' loading (except arsenic and iron) of groundwater is generally low. Reductive dissolution of iron minerals in the presence of organic matter is responsible for high-iron concentration in areas underlain by granitoids. Elsewhere pyrite and arsenopyrite oxidation is the plausible process for iron and arsenic mobilisation. Approximately 19 and 46% of the boreholes have arsenic and iron concentrations exceeding the WHO's (Guidelines for drinking water quality. Final task group meeting. WHO Press, World Health Organization, Geneva, 2004) maximum acceptable limits of 10 μg l-1 and 0.3 mg l -1, for drinking water. © 2007 Springer-Verlag.Item Origin of major dissolved ions in groundwater within the Lower Pra Basin using groundwater geochemistry, source-rock deduction and stable isotopes of 2H and 18O(Environmental Earth Sciences, 2013-11) Tay, C.K.; Kortatsi, B.K.; Hayford, E.; Hodgson, I.O.Hydrochemical and stable isotopes (18O and 2H) analyses of groundwater samples were employed to establish the origin of major dissolved ions in groundwater within the Lower Pra Basin. Results showed that, the major processes responsible for chemical evolution of groundwater include: silicate (SiO4)4- dissolutions, ion exchange reactions, sea aerosol spray and pyrite (FeS2) and arsenopyrite (FeAsS) oxidations. The groundwater is strongly acidic to neutral, with pH generally range from 3.5 to 7.0 pH units and mean 5.9 (±0.5). Approximately 89 % of boreholes had pH values outside the World Heath Organization (WHO, Guidelines for drinking water quality, 2004) guideline value for drinking water due principally to natural biogeochemical processes and therefore, not suitable for potable purposes. Electrical conductivity (EC) range from 57.6 to 1,201 μS/cm with mean 279.3 (±198.8) μS/cm. Total dissolved solids (TDS) range from 32 to 661 mg/L with mean 151.7 (±106.8) mg/L, with 98.6 % of groundwater as fresh (TDS < 500 mg/L). The chemical constituents generally have low concentrations and are within the WHO (Guidelines for drinking water quality, 2004) guideline value for drinking water. The relative abundance of cations and anions is in the order: Na+ > Ca2+> Mg2+ > K+ and HCO3 - > Cl- > SO4 2-, respectively. A plot of ∂18O ‰ against 2H ‰ showed that, ground and surface waters clustered on or closely along the Global Meteoric Water Line, suggesting that, the waters emanated principally from meteoric source with evaporation playing an insignificant role on the infiltrating water. © 2013 Springer-Verlag Berlin Heidelberg.