Abstract:
Phytoremediation and phytoextraction processes have being in-used experimentally and in
real-time operations for the uptake and recovery of metals and heavy metals from
contaminated soils. The current study evaluates Celosia argentea, Corchorus olitorius,
Amaranthus gangeticus, Euphorbia heterophylla for the phytoextraction of Cu, Zn, Cd, and
Pb in soils and hydroponic system. The phytoextraction potentials, the strength of the plants
to tolerate single and multiple heavy metals concentrations were determined with the
addition of enhancement agents (EDTA). Physico-chemical parameters of the soils that
include: pH, conductivity, Cation exchange capacity, soil texture, soil organic matter, and
soil structure (Clay, Loamy and Silt), elemental and heavy metal properties were
determined: K, Na, Pb, Cd, Zn, Cu, and Mg, all the parameters are within the allowable
limits. The concentrations of the heavy metals taken from by all the plants were determined:
For Cu, it ranged from (3.00 ± 0.2 mg/kg -.295 ± 4.3 mg/kg: For Zn, it ranges from (5.60 ±
1.2 mg/kg - 350 ± 5.0 mg/kg): For Cd, it ranged from (2.10±0.2 mg/kg - 155 ± 3.30
mg/kg): For Pb (4.6 ± 0.2 mg/kg - 135 ± 4.0 mg/kg). The plants extracted almost twice the
concentrations taken from the soil experiments in hydroponic solutions
The addition of enrichment agent (EDTA), proved effective in the phytoextraction of
selected heavy metals. Sequential extraction results showed that the heavy metals available
to the plants from the soils are majorly associated with the exchangeable fraction, Fe-Mn
oxides fraction, and partly organic matter fraction. The physiological examination of
Euphorbia hetrerophylla showed that it possesses milky sap latex, which may have helped
in the bioaccumulation of heavy metals. Hydroponic experiments showed that Celosia
argentea produces exudate on exposure to a higher concentration of heavy metals, which
are difficult to extrapolate in soil potted, and field experiments. Under this study, the
evaluation of these plants recommends; labeling Sunflower and Euphorbia heterophylla as
heavy metals extractors, Corchorus olitorius as phytoextractor of lead exclusively and
justified Celosia argentea as a toxic metal indicator plant
