A Study on Heavy Metal Contamination of Yard Soils and its Remediation Potential by Weedy Species

Abstract

The present study was undertaken to analyse the phytoremediation potential of weedy plants growing at dump yards. Two dump yard sites were chosen. Based on the distribution and abundance, 11 weedy species were collected bi-annually using the plot method along with soil samples. Both plants and soils were analysed for heavy metals, and the bioconcentration factor (BCF) was calculated to assess the extent of soil contamination and the remediation potential of weedy plants.

The weed plants collected from two yard sites showed an accumulation of metals, and the rate of accumulation varied among plant species. In the species at the dumping yard site, a higher accumulation of metals was observed for Panicum ciliare (As and Zn), Indigofera hirsuta (Cd and Ni), Chloris barbata (Cr), and Indigofera aspalathoides (Pb). Goiania macrocarpa has accumulated more As, Cu, Ni, and Zn metals in the industrial yard. The accumulation levels in plant tissues were assessed through BCF in the whole plant. The study results confirm that Panicum cillarae, Indigofera hirsuta, and Sida acuta at dump yard soils and Indigofera aspalathoides at industrial yard soil reported BCF values of more than one, indicating the potential of these plants for phytoremediation for selected metals.

Six of the 11 weedy species were specific to accumulating metals from yard soils. They are Indigofera aspalathodies for Cd; Sida acuta, Panicum ciliare, and Indigofera hirsuta for As; Oldenlandia corymbose for Zn and As; and Gouinia macrocarpa for Zn. The findings suggest that weedy species growing naturally in the two yards sites adopted higher concentrations of the metals and can accumulate them to a higher degree in their body parts.