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.
Background: Many years of gold mining in Ghana has generated huge environmental legacy issues, particularly contamination from heavy metals and metalloids. The present study evaluated the contamination from arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg) and lead (Pb) in sediment cores at Bibiani, a historical gold mining town in Ghana. The study took a retrospective look at these contaminations by conducting sediment core analysis of heavy metals in sediments collected from Lake Amponsah in the Bibiani district. Sediment cores were sampled to a depth of 30 cm.
Results:The Lake was found to be undergoing sedimentation at an average rate of 1.76 cm/y. There was marginal decline in Hg concentrations over the past two decades (from the 1990s to 2010s), while the other metals showed relatively increasing trends. The Hg policy restricting Hg usage in Ghana since 1989 has contributed to the recent marginal decline of Hg in the sediment. It was found that small-scale miners illicitly applied Hg but used crude retrofits to recover some of the Hg during the gold amalgamation process. This perhaps contributed to the marginal decline being observed in the sediment compartment with depth. Nevertheless, there was concern of potential risk of exposure to gaseous Hg during the amalgamation process.
Conclusion:Based on findings of this study, Hg legislation in Ghana should be enforced to the latter as it has shown good sign of reducing environmental contamination from this metal.
Wastewater treatment plants receive sewage containing high concentrations of bacteria and antibiotics. We assessed bacterial counts and their antibiotic resistance patterns in water from (a) influents and effluents of the Legon sewage treatment plant (STP) in Accra, Ghana and (b) upstream, outfall, and downstream in the recipient Onyasia stream. We conducted a cross-sectional study of quality-controlled water testing (January–June 2018). In STP effluents, mean bacterial counts (colony-forming units/100 mL) had reduced E. coli (99.9% reduction; 102,266,667 to 710), A. hydrophila (98.8%; 376,333 to 9603), and P. aeruginosa (99.5%; 5,666,667 to 1550). Antibiotic resistance was significantly reduced for tetracycline, ciprofloxacin, cefuroxime, and ceftazidime and increased for gentamicin, amoxicillin/clavulanate, and imipenem. The highest levels were for amoxicillin/clavulanate (50–97%) and aztreonam (33%). Bacterial counts increased by 98.8% downstream compared to the sewage outfall and were predominated by E. coli, implying intense fecal contamination from other sources. There was a progressive increase in antibiotic resistance from upstream, to outfall, to downstream. The highest resistance was for amoxicillin/clavulanate (80–83%), cefuroxime (47–73%), aztreonam (53%), and ciprofloxacin (40%). The STP is efficient in reducing bacterial counts and thus reducing environmental contamination. The recipient stream is contaminated with antibiotic-resistant bacteria listed as critically important for human use, which needs addressing.
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