Rangeland Plants Potential for Phytoremediation of Contaminated Soils with Lead, Zinc, Cadmium and Nickel (Case Study: Rangelands around National Lead & Zinc Factory, Zanjan, Iran)

Abstract

There are many remediating methods for the polluted soils but only phytoremediation is a cost effective, environmental friendly, aesthetically pleasing approach that is most suitable for many countries. The purpose of this study was to investigate the potential of native plants for phytoremediation of contaminated soils with lead, zinc, cadmium and nickel in the rangelands around National Lead & Zinc Factory, Zanjan, Iran. Sampling was done at 11 sites on May, 2014 and plant samples were collected from 14 native plant species. Three soil samples were taken at each site. Soil samples were taken from the rooting zone. Extraction of Pb, Zn, Cd and Ni from plants was done by acid digestion. Plant samples were digested in the di-acid mixture (3:1) of nitric acid (HNO₃) and perchloric acid (HClO) and soil samples were digested with 4M HNO₃ acid. Metals of Pb, Zn, Cd and Ni were extracted from plant and soil samples were determined using Inductively Coupled plasma Optical Emission Spectroscopy “ICP-OES". In general, the results showed that no hyperaccumulators of Pb and Zn were identified in the area. All plants were classified as low lead accumulators, excluder and moderate accumulators, low zinc accumulators or excluders; though Pb and Zn concentrations in the plants were higher than standard range. Standard range of lead and zinc in rangeland plants is 0.2-20 and 1-400 mgkg^-1, respectively whereas the species of <em>Brassica juncea</em> and S<em>cariola orientalis </em>were classified as Cd hyperaccumulators and <em>Scariola orientalis and Echium amoenum </em>were classified as Ni hyperaccumulators. The normal value of Cd and Ni in these plants were 0.1-2.4 and 0.02-5.0 mgkg^-1, respectively. Thus, these native plants had an implication of carrying out phytoremediation in the rangeland soils around National Iranian Lead & Zinc Factory, Zanjan.