Phytoremediation Of Some Heavy Metals From Mined Soils: A Case Study Of Bontesso In Amansie West District, Ghana.
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Date
2019-02
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KNUST
Abstract
Bioremediation is a promising technique presently being practiced to extract heavy metals from mined tailings on commercial scale in many developed countries. This technology of remediating heavy metals contaminated soils has overriding advantage on conventional technologies. The hyperaccumulation potential of four plant species, Chromolaena ordorata (CO), Paspalum vaginantum (PV), Chrysopogon zizanioides (CZ) and Cynodon dactylon (CD) were evaluated using soil polluted by mining activities from Bontesso in the Amansie West District of Ashanti Region of Ghana. Nine treatments were used in the study: Control, CO, CZ, PV, CD, CO+PV, CO+CD, CZ+PV and CZ+CD samples. The experiment was laid out in a randomized complete block design with six replicates. The soils’ physico-chemical properties and the concentration of some selected heavy metals (As, Cd, Cu, Ni and Pb) were determined. Plant growth and dynamics of pH, electrical conductivity and heavy metals concentrations in the soil were monitored for a nine-week study period. Accumulation, bioaccumulation and translocation potentials were determined. Okro and tomato were cultivated on treated soils and concentrations of metals in the crops were determined. The results of the study show that, soil in the study area are acidic with average pH range of 5.71-6.24 and of loamy-sand texture. Soil organic carbon, total nitrogen and Phosphorous contents are 0.21 %, 0.09 % and 4.79 mg/kg soil, respectively. Concentrations of Pb, Cu, Ni, As and Cd 40.22, 30.54, 23.58, 6.18 and 0.27 mg/kg, respectively) in the area are generally below the permissible limits set by WHO. Combined use of CO and PV (CO+PV) plant species resulted in higher reductions in the concentrations of all measured metals from the soil. The species accumulation and bioaccumulation factors also show their specific metal affinity and time limitation for their application. The implication of this research is to help reduce threats on national food security and to increase the food buscket as far as agriculture is concerned.
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This Dissertation Is Presented To The Department Of Materials Engineering In Partial Fulfilment Of The Requirements Of Master Of Philisophy Degree In Environmental Resources Managemnt