Heavy metals contaminations of soil and water at Agbogbloshie Scrap Market, Accra

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The levels of heavy metals contaminations of both soil and water were investigated at Agbogbloshie scrap market, Accra between December, 2011 and September, 2012. Seven different heavy metals (Zn, Cr, Cu, Cd, Pb, Co and Ni) were measured in eight (8) sampling sites namely 101 (burning site with no disposal), 102 (burning but no disposal), 103 (Big lagoon), 104 (small lagoon), 105 (dismantling site), 106 (no burning or disposal site), 107 (disposal site but no burning) and 108 (disposal and burning site). The sampling sites were considered because of the dismantling and burning of the electronic products to recover metals. Eighteen (18) soil samples and six (6) water samples were used for the study. The soils and water samples collected from the different sites were analyzed at Ecological laboratory of the University of Ghana, Legon. Atomic Absorption Spectrophotometer (AAS) was used for the determination of the heavy metals in the soil and water samples. The mean concentrations of soil samples ranged from 173.60 to 899.90, 9.57 to 57.73, 226.80 to 6291.33, 3.47 to 13.80, 127.83 to 1392.67, 17.03 to 64.43 and 6.47 to 62.53 (mg/kg dry weight) for Zn, Cr, Cu, Cd, Pb, Co and Ni respectively. The contamination levels of Zn, Cu and Pb were high while the rest of the metals (Cr, Cd, Co and Ni) in the soil samples were low. Zn and Pb concentrations exceeded the Dutch target values (Zn: 140 mg/kg and Pb: 85 mg/kg) in all the sampling sites. Their concentrations in site 101 (Zn: 810.53 mg/kg and Pb: 1392.67 mg/kg), 102 (Zn: 899.90 mg/kg and Pb: 642.27 mg/kg) and 105 (Zn: 860.17 mg/kg and Pb: 706.60 mg/kg) were higher than the Dutch intervention values (Zn: 720 mg/kg and Pb: 530 mg/kg). Cu concentration in all the soil samples exceeded the concentration admitted by the Dutch guidelines of the new Dutch list. The Cu concentrations in all the sampling sites for the soils were high. The mean values of the water samples ranged from 0.039 to 0.060, 0 to 0.012, 0.007 to 0.019, 0.069 to 0.074 and 0 to 0.23 (mg/L) for Zn, Cu, Cd, Co and Ni respectively. No Cr and Pb were detected in all the water samples, an indication of lower instrumental detection limit. It was noted that the dismantling and burning of the electronic products to recover metals had a direct impact on the concentrations of the heavy metals determined.
A thesis submitted to the Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the degree of Master of Science degree in Environmental Science, 2014