[Optimum operating conditions in the phytoremediation of contaminated soils with Lead and Cadmium by native plants of Iran]

ABSTRACT

In recent decade, phytoremediation technology is regarded very important because of its simplicity, inexpensiveness and use of natural resources and solar energy. In this study, we investigated the efficiency of remediation of contaminated soil with Lead and Cadmium by using native plants of Iran. We selected three native plants of Iran [Abutilon theophrasti, Amaranthus retoflexus and Zea maize] for this study. Extraction of soil and plant samples was performed by use of HNO3 ,HCl and HNO3, HClO4 and H2SO4 respectively. Concentrations of Lead and Cadmium in soil and plants were determined by Perkin-Elmer 603 atomic absorption spectrophotometer. Lead concentration in the roots of plants [Alkaline soil] was more than those in their shoots. In acidic soil [with exception of Zea maize], concentration of Lead in the shoots was more than its concentration in the roots of the plants. Concentrations of lead in the roots and shoots of Abutilon theophrasti, Amaranths and Zea maize in alkaline soil were [54.5 and 25.5 mg/kg], [69 and 37.6mg/kg] and [47 and 32mg/kg] respectively, and its respective concentrations in acidic soil were [71.4 and 92.5 mg/kg], [89 and 120.5mg/kg] and [85 and 66.7 mg/kg]. Cadmium concentrations in alkaline soil were [6.5 and 4mg/kg], [8 and 6.2 mg/kg] and [5.6 and 3.4 mg/kg] and in acidic soil were [5.8 and 4.5 mg/kg], [7.6 and 5.4mg/ kg] and [6 and 4.8 mg/kg] respectively. Plants in group 3 produced less biomass than those in control group, group 1 and group 2. Considering the increased rate of absorption of Lead and Cadmium and the amount of biomass produced by Zea maize and Amaranthus retoflexus in the acidic and alkaline soil, use of these native plants is recommended for refining the soil contaminated with heavy metals