Potentials of adiantum raddianum and nephrolepis exaltata for phytoextraction of heavy metals in spiked soils
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Date
2013-08-14
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Abstract
Phytoremediation is an emerging technology that employs the use of higher plants for the cleanup of contaminated environments. Research has demonstrated that selected plant species possess the genetic potential to remove, degrade, metabolize, or immobilize a wide range of contaminants. Despite this tremendous potential, phytoremediation is yet to become a commercial technology. This study was carried out to assess the potential of using Adiantum raddianum (L) and Nephrolepis exaltata (L) for phytoextraction of heavy metals in a spiked soil and the effect of EDTA as mobilizing agents. Heavy metal concentrations in soil and plant parts were measured using atomic absorption spectrometer. N. exaltata was able to extract more heavy metals compared to A. raddianum in shoots and roots when grown on spiked as well as spiked and EDTA amended soil samples. The concentrations of metals in both plants were significantly increased when EDTA was added to soil samples. Mean heavy metal concentration was higher in roots than shoots of both plants except Zn which had higher concentration in both plant shoots when grown on spiked as well as spiked and EDTA amended soil samples. In the experiment where soil was spiked and treated with EDTA as mobilizing agent, N. exaltata had bioconcentration indices for Cr and Zn less than one but indices for Pb, Cd and Ni were above 1. In the same experiment, the bioconcentration factor of Pb, Zn, Cr and Ni in A. raddianum were less than 1 but index for Cd was greater than 1. Translocation of Zn by N. exaltata in the experiment where spiked soil was treated with EDTA was greater than 1 making the plant suitable for phytoextraction of a Zn-contaminated site. The plant is however suitable for phytostabilization of Cd, Pb, Cr and Ni-contaminated sites as translocation values were less than 1. A. raddianum had translocation values greater than 1 for Zn and Ni while indices for Cd, Pb and Cr were less than 1 in a spiked and EDTA treated experiment. This makes the plant suitable for Zn and Ni phytoextraction and phytostabilization of Cd, Pb and Cr contaminated sites as metals were mainly stored in roots.
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A thesis submitted to the Department of Environmental Science
Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the degree of
Master of Science in Environmental Science, 2013