International Journal of Research in Environmental Studies
ISSN: 2059-1977
Vol. 8(2), pp. 27-35, April 2021
doi.org/10.33500/ijres.2021.08.003



Assessing the potential of Ageratum conyzoides for the phytoremediation of lead-polluted soils

Ademola F. Aiyesanmi*, Iyalabake O. Ajayi and Afamefuna E. Okoronkwo

Department of Chemistry, The Federal University of Technology, Akure, Nigeria.

*To whom correspondence should be addressed. E-mail: afaiyesanmi@futa.edu.ng, demolaktp@yahoo.co.uk.

Received 05 April, 2020; Received in revised form 06 May, 2020; Accepted 12 May, 2020.

Abstract


Keywords:
Polluted soil, Lead, Remediation, Ageratum conyzoides, Chelating agents.


Remediation of heavy metal contaminated soil has been a serious challenge to most developing nations of the world, because the conventional remediation strategy for heavy metal-contaminated soils involves excavation, though effective but extremely costly and disruptive. In this study, Ageratum conyzoides was investigated for its potential to remediate lead-polluted soil both naturally and chelate-induced forms under green house conditions. Pot experiments were conducted in nursery beds using lead spiked soils. Varing concentrations of lead salt solution were used. The plant was grown both directly on the soil and on soils modified with ethylenediaminetetraacetic acid (EDTA) and oxalic acid. The concentration of lead absorbed by the plants in the unmodified soil gradually increased with time. The maximum concentration absorbed in the root over a four-week study period was 37.12 mg/kg, while that of the shoot was 36.33 mg/kg. This increased significantly in the EDTA and oxalic acid-modified soils with maximum values (Root: 84.98.mg/kg, Shoot: 85.19 mg/kg) and (Root: 81.89 mg/kg, Shoot: 80.16 mg/kg), respectively. The plant growth was not affected by the increase in concentration of lead absorbed by the roots and shoots, when compared with the control, which implies that Ageratum conyzoides exhibited tolerance for lead-contaminated soils. The transfer factor ranged from 0.62 - 0.95 in unammended lead-contaminated soil; 0.75 - 1.04 and 0.84 - 0.98 in soils amended with chelating agents (EDTA and oxalic acid, respectively). Thus EDTA and oxalic acid can be used to enhance the absorption of lead from contaminated soil by A. conyzoides.

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