Hydrochemical Evolution of Ground and Surface Water within the Amansie and Adansi Districts of the Ashanti Region, Ghana

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 respectivelyin groundwater within the Amansie and Adansi Districts. Results show that, silicate weathering and ion-exchange reactions are the major processes influencing groundwater chemistry within the 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 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: Ca2+ > Na+ > Mg2+ > K+ and HCO3- > Cl- > SO42-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-HCO3 and Na–Cl have been delineated, with Ca-Mg-SO4, Na-Mg-Ca-HCO3 and Na- Cl-SO4 as minor water types. Groundwater within the districts principally evolves from fresh Ca–Mg–HCO3 type water into Na–HCO3 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

Assessment of Nutrients Levels in Groundwater within the Lower Pra Basin of Ghana

The level of concentration of nitrates, phosphates, and sulphates was determined in groundwater within the Pra Basin to ascertain the degree of anthropogenic influence via the application of fertilizer and other agro-chemical to farmlands by farmers. Sixty-five (65) boreholes in forty-five (45) communities were analysed between January and April 2012 to cover the dry season and between June and October 2012 to cover the wet season. The results show that nitrate for both seasons range between 0.011 mg/l and 5.01 mg/l and therefore within the WHO (2006) guideline value of 10 mg/l, whilst that of phosphate range between 0.01 mg/l and 3.08 mg/l and therefore outside the USEPA guideline value of 2.5 mg/l. Sulphate recorded a range between 1.60 and 96.2 mg/l and therefore within the WHO (2006) guideline value of 250 mg/l. The concentration levels of the two nutrients of the parameters, nitrates and phosphate were correlated against borehole depth and the results show a weak positive and negative correlation for nitrate and phosphate respectively. There was thus, an indication that the levels of all parameters, nitrate, phosphate and sulphate are not yet a threat to groundwater in the basin

Assessment of trace metal contamination by geochemical normalisation in sediments of two lagoons: A comparative study of the Kpeshie and Muni lagoons, Ghana

Heavy metal contamination status of bottom sediments of two lagoons was compared by the employment of Enrichment Factor (EF) analysis for Iron (Fe), Manganese (Mn), Cupper (Cu), Lead (Pb), Chromium (Cr), Nickel (Ni), Silver (Ag), Zinc (Zn) and Mercury (Hg). Kpeshie Lagoon recorded enrichment (EF ≥ 1) for Cd, Pb, Ag, Hg and Zn, whilst Muni Lagoon recorded enrichment for Cd, Mn, Ag, Hg and Zn as metals of anthropogenic influence. Kpeshie, situated in a highly urbanized area, has 75% spatial distribution of Pb enrichment. The assessment shows that Ag and Hg are the most enriched metals in the sediments of both Lagoons, reaching extremely severe levels. Only Mn showed statistically significant difference in mean concentration of metals for both Lagoons. Pearson correlation matrix indicated that Pb had a strong relation with Ag, Hg and Zn (r = 0.956; p < 0.05) which is significant in Kpeshie. It also had a strong association with Ag and Hg but not with Zn (r = 0.240) in the Muni. The study clearly delineates Pb as a pollutant that designates the urban status of Kpeshie. Its associated metals; Ag, Hg and Zn which may be coming from a common source are from industrialized zones

Effects of small-scale gold mining on heavy metal levels in groundwater in the Lower Pra Basin of Ghana

Abstract The effects of small-scale gold mining activities on heavy metal levels in groundwater were determined for the Lower Pra Basin of Ghana. Sixty five boreholes in 45 communities were analysed between January 2012 and April 2012 for the dry season and June and October 2012 for the wet season. The test for significance and the use of cluster analysis, a multivariate approach, clearly delineate Cu, Zn, Cd and Hg as possible anthropogenic contributors, whilst As, Se and Pb could be both anthropogenic and natural geochemical process contributors of metal level concentrations in the groundwater. The analysis shows generally low pH values in the basin with more than 95% of dry season and almost all wet season values being acidic or slightly acidic. Approximately 35% of boreholes in the wet season recorded values for cadmium above WHO guideline value of 3.0 µg/l with almost all dry season values falling below 3.0 µg/l except for two boreholes. Generally, high values were recorded for iron, manganese, lead, Al and Hg. In general, lead, copper, cadmium and manganese showed higher wet season values than dry season suggesting anthropogenic influence

Risk of heavy metal ingestion from the consumption of two commercially valuable species of fish from the fresh and coastal waters of Ghana.

The need to evaluate the human health safety of fishery resources remain urgent in the mist of the ever-increasing fear of heavy metal toxicity from the consumption of Ghana's fisheries resource, as a consequence of pollution from several anthropogenic activities including artisanal gold mining. Nevertheless, the bigeye grunt (Brachydeuterus auritus) and Bagrid catfish (Chrysichthys nigrodigitatus) remain commercially valuable fish species in West Africa and continue to attract high patronage.Forty-five specimens each of C. nigrodigitatus and B. auritus collected from the Weija Dam and the Tema Fishing Habour in Ghana, between June and September 2016, were analysed for seven heavy metals using Atomic Absorption Spectrometry.Lead and Cadmium were below detection in all samples while Cu was not detected in B. auritus. Levels of the remaining metals (mg kg-1) were below FAO/WHO maximum permissible limits in fish and occurred in the rank order Se (3.5) > Zn (2.34) > Cu (0.59) > As (0.37) > Hg (0.19) in C. nigrodigitatus and Se (2.97) > Zn (2.28) > Hg (0.31) > As (0.21) in B. auritus. Only As in C. nigrodigitatus recorded Estimated Weekly Intake (EWI) greater than FAO/WHO Provisional Tolerable Weekly Intake (PTWI). Also, As in C. nigrodigitatus and Hg in B. auritus had Targeted Hazard Quotient (THQ) greater than 1 for individuals consuming the fishes on daily basis and therefore, raising concerns. However, for both species of fish, cancer risk of As was 1 in 10,000,000,000 and modified Health Benefits values of Se (HBVSe) were positive indicating the health risks that might accompany Hg exposure would be negated. Since toxicity depends on the concentration and quantity of a pollutant consumed, safe maximum consumption rate of C. nigrodigitatus based on As concentrations was 0.21 mg per day and that of B. auritus was 0.058 mg per day for Hg. With an average of 0.227 kg fish per meal of an adult human, these translated into not more than 24 C. nigrodigitatus and nine (9) B. auritus meals in a month but because fish is consumed at 0.0685 kg per person per day in Ghana, these values respectively translates to 93 and 30 safe days of consumption per month.At the rate of 0.0685 kg fish per person per day that fish is consumed in Ghana, the consumption of the two species of fish in Ghana would essentially be of little or no consequence to consumers

Human health risk assessment parameters of heavy metals from the consumption of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters of Ghana.

<p>Human health risk assessment parameters of heavy metals from the consumption of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters of Ghana.</p

Frequency distribution of metal concentrations in the muscle tissues of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> from the waters of Ghana.

<p>Note: Pb, Cd and Cu were excluded from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194682#pone.0194682.g001" target="_blank">Fig 1</a> because Pb and Cd were below detection in all samples while 96% of the C. nigrodigitatus and 100% of the B. auritus samples had Cu levels below detections.</p

Comparison of heavy metals concentrations between the muscle tissues of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> from the waters of Ghana.

<p>Note: <i>Mean ± SD with different letters in columns are significantly different (Mann–Whitney U test</i>, <i>p > 0</i>.<i>05)</i>.</p

Weight of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters in Ghana.

<p>Weight of <i>Chrysichthys nigrodigitatus</i> and <i>Brachydeuterus auritus</i> respectively from the fresh and coastal waters in Ghana.</p

Map of Ghana showing the Weija Dam and the Tema fishing harbour where fish specimens were collected.

<p>Map of Ghana showing the Weija Dam and the Tema fishing harbour where fish specimens were collected.</p