Comparative study of phytoremediation of chromium contaminated soil by Amaranthus viridis in the presence of different chelating agents

Abstract

Chromium is a harmful heavy metal to the environment due to the toxicity induced by it to plants and other living organisms. High concentration of Cr in soil poses severe toxicological problems ecosystem. Phytoremediation using different plants is an economical and environment-friendly method for removing Cr from soil. The addition of chelating agents augments the phytoextraction using plants.The present study aimed to augment the Cr phytoremediation capacity of Amaranthus virdis, a predominant plant species in the Cr-contaminated open dumpsites of Bangalore. . Phytoextraction of Cr by Amaranthus viridis was studied in the presence of different chelating agents viz. ethylenediaminetetraacetic acid (EDTA), citric acid (CA), growth promoting hormone- indoleacetic acid (IAA) and NPK fertiliser. A. viridis grown under different concentrations (5, 10 and 20 mg/Kg) of Cr were treated with 0.5g EDTA/Kg of soil, 0.5g CA/Kg of soil, 1mg IAA/Kg of soil and NPK (125 mg of nitrogen, 45 mg of phosphorous and 156 mg of potassium per Kg of soil). Results indicated that CA, at 10 mg/kg Cr supply, induced the highest uptake (up to 29.25 µg/plant). Furthermore, the study revealed that CA amendment induced maximum Cr uptake in A. viridis at all levels of Cr supply as compared to other amendments. This was due to the increased solubility of Cr in the presence of citric acid and the amelioration of oxidative stress due to Cr to plants by citric acid. This study inferred that the non-hyperaccumulating plant, A. virdis could be used as a phytoremediator for Cr in the presence of citric acid in the places where it is grown abundantly.