Mercury and cadmium accumulation in selected weed plants: Implications for phytoremediation

With increasing use of heavy metal by human activities, ecosystems have and are being contaminated with heavy metals. Contaminated soil can be remediated by chemical, physical or biological methods. Phytoremediation is an on-site remediation strategy that employs plants to remove non-volatile and immiscible soil contents. To enhance phytoremediation as a viable strategy, fast growing plants with high metal uptake ability and rapid biomass gain are needed. The present study was conducted to find useful weed species for Cadmium (Cd) and Mercury (Hg) phytoremediation. Seven species of locally available common weeds were grown for two months in pot culture with three treatment doses of Cd and Hg (5, 10 and 25 mg / kg dry weight (DW)) using HgCl2 and CdCl2 salts. The Cd and Hg concentrations in the dry plant biomass were determined by Atomic absorption spectrometry. The concentrations of Cd were relatively higher in Trianthema portulocastrum (6.0720 mg/kg), Jatropha curcas (4.8990mg/kg) and Ipomoea cornea (3.0108 mg/kg). Higher concentrations of Hg were recorded in Ipomea cornea (3.1500 mg/kg) and Jatropha curcas (2.3175 mg/kg). These results suggest that Ipomoea cornea and Jatropha curcas accumulate Cd in higher concentrations and they also accumulate Hg significantly. Trianthema portulocastrum and Jatropha curcas accumulate high concentrations of Cd then Ipomoea cornea. Based on the present investigation it is suggested that Ipomoea cornea and Jatropha curcas have better accumulation capacity for Hg remediation and Trianthema portulocastrum, Jatropha curcas and Ipomoea cornea can be used Cd phytoremediation.

Author(s): Kavitha Kadirvel K and M Jegadeesan

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