Assessment of the Pollution Status of Butuah Lagoon in the Sekondi-Takoradi Metropolis, Western Region, Ghana

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The water quality of Butuah Lagoon was monitored together with the concentrations of seven heavy metals (As, Cu, Pb, Zn, Fe, Cd and Hg) determined in the sediments, muscles of Tilapia fish and lagoon water using Atomic Absorption Spectrophotometer (AAS 220 Model) except Hg which was determined using the Automatic Mercury Analyzer (HG 6000 Model). The same parameters were determined in an effluent discharging into the lagoon from an Industrial Complex. The results indicated that the concentrations of heavy metals in the effluent samples were generally below the recommended standards. The effluent discharged into the lagoon was not a major source of pollution indicating that there are other major sources of pollutants discharging into the lagoon. When compared with ISQG (2002), heavy metal concentrations of sediments from Butuah Lagoon recorded higher values except for Hg which was below the permissible limits. The highest levels of pollutants were found in the sediment followed by fish and the least being recorded in water. The concentrations of As, Cu, Pb, Zn, Fe, Cd and Hg in sediments were 94.1%, 92.7%, 88.1%, 81.3%, 95.4%, 92.7% and 27.4% higher than those obtained in muscles of fish. Similarly, the concentrations of As, Cu, Pb, Zn, Fe, Cd and Hg in sediments were 100%, 99.9%, 99.4%, 99.8%, 100%, 99.3% and 100% higher respectively than in water samples from the same lagoon. The range of heavy metal concentrations in fish during the sampling period was 1.93 mg/kg to 8.13 mg/kg for As, 0.08 mg/kg to 8.00 mg/kg for Cu, 1.00 mg/kg to 13.43 mg/kg for Pb, 15.20 mg/kg to 37.67 mg/kg for Zn, 33.17 mg/kg to 210.06 mg/kg for Fe, 0.00 to 0.97 mg/kg for Cd to 0.008 mg/kg to 0.014 mg/kg for Hg. In terms of location the midstream was more polluted than downstream which was more polluted than upstream. Monthly levels of pollutants determined over four months indicated that the concentrations decrease with the onset of the wet season. The use of Butuah Lagoon as source of fish (Tilapia) supply should be discouraged
A Thesis Submitted to the Department of Environmental Science, Kwame Nkrumah University of Science and Technology, Kumasi, in Partial Fulfillment of the Award of Master of Science in Environmental Science, July-2012