Chelator-Enhanced Phytoextraction of Copper And Zinc By Impatiens balsamina L. (Kamantigi)

Abstract

INTRODUCTION

Heavy metal pollution in soil has become a critical environmental concern due to its potential adverse ecological effects. Phytoextraction is the most common form of phytoremediation that involves the accumulation of heavy metals in the roots and shoots of phytoremediation plants. Naturally occurring chelating agents are more favorable for the phytoextraction of metals due to their nontoxic and biodegradable property. The present study investigated the potential of gallic acid and citric acid in enhancing the phytoextraction of copper and zinc by Impatiens balsamina (kamantigi).

METHODS

The growth response of I. balsamina to the different concentrations of citric acid and gallic acid (high 30mg/kg; medium 20 mg/kg; and low 10 mg/kg) was determined by measuring the shoot heights. Concentrations of accumulated copper and zinc inthe plant parts after 2nd, 4th and 6th week of transplanting were determined using AOAC official method 999.11. Aliquots of the plant and soil solutions were taken from the concentrations of the following heavy metals; copper and zinc using a graphite atomic absorption spectrophotometer.

RESULTS

Copper showed a negative response to a high amount of citric acid causing the shoot heights increment to decline. Shoot heights of plants treated with zinc were abruptly increased in all concentrations of gallic acid and citric acid. The concentrations of accumulated copper in the plants contaminated with gallic acid and citric acid were concentrated in the roots of I. balsamina. However, the concentrations of accumulated Zn were highest in the leaves of the plants. The average concentration of the accumulated copper in high concentration (30mg/kg) of citric acid was 714.41 mg. kg-far better than the control with 261.36 mg.kg-. High concentration of citric acid enhanced 362.07% Cu in I. balsamina. The use of gallicacid and citric acid in the enhanced phytoextraction of Zn were negligible. The overall research showed that citric acid was a potentially suitable chelator in enhancing the phytoextraction of copper.

DISCUSSIONS

The amount of accumulated copper was beyond the permissible limit in the plant tissues. However, the amount of accumulated zinc was still in the permissible limit for plant tissues. The use of gallic acid and citric acid in the phytoextraction of zinc were negligible which might due to the relatively low concentration of zinc in soil.