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Title: Phytoremediation of Heavy Metal Contaminated Soil Using Leucaena Leucocephala: A Case Study at Anglogold Ashanti Obuasi Ghana
Authors: Boateng, Yaw
Issue Date: 13-Feb-2015
Abstract: Phytoremediation is one of the low cost biotechnology technique for the reclamation of contaminated mined sites. This study investigated the use of Leucaena leucocephala as a potential plant species for phytoremediation of heavy metal contaminated soils. The phytoremediation capability of the plant was studied at the Nursery and Re-vegetation unit of AngloGold Ashanti in Obuasi. Tailings from the Sansu Tailings Dam was amended with top soil from Mampanhwe and three supplements to produce 10 treatments regimes, which were; T1 - Tailings alone, T2 - Tailings + chelator (EDTA), T3 - Tailings + Fertilizer (NPK), T4 - Tailings + Fertilizer (NPK) + chelator (EDTA), T5 - Tailings + PKC, T6 - Tailings + PKC + chelator (EDTA), T7 - Tailing + Topsoil (3:2), T8 - Tailing + Topsoil (2:3), T9 - Tailing + Topsoil (1:1) and T10 - Topsoil alone. Treatment soils of 5 kg were put in poly-pots. Each of the 10 treatments was replicated 6 times and harvesting was done twice at 45 and 75 days after transplanting. A total of 120 poly-pots were prepared. The concentrations of six heavy metals (As, Fe, Pb, Zn, Cd and Cu) were determined, in samples of shoots and roots from each harvest, using an Atomic Absorption Spectrometer. The levels of heavy metals were highest in the roots than in the shoot. The fertilizer (NPK) and the organic manure (PKC) did not have any effect on the biomass. The highest accumulation ratio (22.58 and 32.91) of heavy metals in shoots for both harvests was obtained in T2 for As. The highest accumulation ratio (35.76 and 51.39) of heavy metal in roots was obtained in T5 for As in both harvests. The highest percentage heavy metals reduction in soils was recorded for Zinc (Zn) for both harvests in T2 at 71.30% and 95.96% respectively. Except for As in T4, the amendment of treatment soils with chelator (EDTA) was not effective as the translocation of heavy metals into the shoots was not enhanced by its addition. T2 was the best treatment regime in enhancing the accumulation of heavy metals for both harvest in the order: (T2>T5>T6>T4>T3>T7>T9>T8). In general the levels of heavy metal accumulation increased with the addition of the supplements (Chelator, PKC and NPK) and performed much better than the tailings/soil mixtures. Between the tailings and soil mixtures ratios, T7 (3:2) was the best combination for increased heavy metal accumulation in the plant. Bioaccumulation ratios obtained were all less than 1 (<1) but increased from first to second harvests. Translocation factors greater than 1 (>1) was recorded for As in T4 (tailing + NPK + chelator) for both harvests and T9 (1:1) which was equal to 1 (=1) at the second harvest. Zn in the control also had TF greater than 1 (>1) in the second harvest. The results show that the plant is a phytoextractor and when aided with the addition of supplements, could be more effective in accumulation of heavy metals as a hyperaccumulator on long term cultivation.  
Description: This Thesis is Presented to the Department of Theoretical and Applied Biology in Partial Fulfilment of the Requirements of Master of the Science Degree in Environmental Science, 2014
URI: http://hdl.handle.net/123456789/6835
Appears in Collections:College of Science

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