Assessment of the Pollution Status of Butuah Lagoon in the Sekondi-Takoradi Metropolis, Western Region, Ghana
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Date
2012-07-20
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Abstract
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
Description
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