Physico-Chemical Quality of Water Sources in the Gold Mining Areas of Bibiani

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Physico-chemical quality of ground and surface waters from Bibiani and its environs was conducted between November, 2009 and April, 2010. This study was undertaken to determine whether physical, chemical and trace metal contamination of water sources in Bibiani is as a result of mining or geochemical and biochemical processes within the environment. Levels of trace metals (Arsenic (As), Iron (Fe), Manganese (Mn), and Copper (Cu)), physical parameters (pH, Total Dissolved Solids (TDS), Electrical Conductivity (E.C) and Temperature) and chemical parameters (Alkalinity, Hardness, Phosphate and Cyanide (CN)) in water resources were determined. Water samples were collected from 10 sampling points including 2 streams, 2 rivers, 3 boreholes and 3 hands dug wells for trace metal analysis. The results showed that groundwater (pH range 5.77 – 6.56) was slightly acidic (low pH) compared to surface water (pH range 6.57 – 7.14 pH units). Groundwater electrical conductivity ranged from 360.17 to 957.12 µS/cm whereas that of surface water ranged from 451.67 to 774.72 µS/cm. Mining related contaminants detected in water samples in this study were As (ranging from values <0.001 to 0.002 mg/l), CN (minimum and maximum concentrations of 0.002 and 0.036 mg/l respectively), Mn (ranging between 0.1 and 0.72 mg/l) and Fe (with 0.32 and 3.035 mg/l being the respective minimum and maximum values). Groundwater (GW1, GW2, GW3, GW4, GW5 and GW6) samples were found to contain more Mn (at GW3 and GW4 with concentrations of 0.72 and 0.5 mg/l respectively) and Fe (at all the sampling points with concentrations ranging from 0.32 to 1.47mg/l) contaminants. Surface water (SW1, SW2, SW3, and SW4) bodies were also found to have more As (at SW2 with a value of 0.02 mg/l) and Fe (also occurring at all the sampling points with values between 1.246 and 3.035 mg/l) contaminants. Relationships between trace metals and chemical and physical parameters in groundwater showed that As had a strong negative correlation with alkalinity (r = - 0.866) and Fe also had a strong positive correlation with electrical conductivity (r = 0.906). In surface water, Mn showed a strong positive correlation with phosphate (r = 0.871) but correlated negatively with alkalinity (r = - 0.93). Fe also correlated negatively with electrical conductivity (r = - 0.864) in surface water. Compared to WHO / EPA guideline, few of the ground and surface water supplies had one or more trace metal (Fe, As and Mn) levels outside acceptable limits set for drinking water. Most of them however have levels safe for human consumption.
A Thesis submitted to the Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the degree of Master of Science in Environmental Science, July-2012