Phytoremediation of Cadmium in Polluted Effluents by Pharagmites Australis in Constructed Wetland

Background and Objectives: With increasing population, the process of contamination of water resources has intensified and humans need new and inexpensive ways to refine and improve water quality. Heavy metals are the environmental pollutants that originate mainly from industrial and agricultural activities and are found in all parts of the industrial communities. This research was conducted to evaluate cadmium stress resistance for Pharagmites australis in greenhouse conditions in University of Jiroft. Methods: The experiments were conducted in a completely randomized design with factorial arrangement with two factors and three replications. Experiments were included: cadmium as the first factor and levels of metal stress including 0, 50, 100, 200, 400, 600, 800, 1000 mg.kg-1 soil for greenhouse experiments as the second factor. The resistance of Pharagmites australis to cadmium stress at deposition stage to full growth in greenhouse conditions was investigated and the concentration of cadmium in the underground organs and aboveground organs and soil pots were measured. Results: results of Greenhouse experiments showed that with increasing in metal concentrations, it's absorbing with underground organs and aboveground organs were increased. However, impressive accumulation of cadmium was in underground organs and its translocation and accumulation in aboveground organs has been reported much less. With absorption and accumulation of metal in underground organs, ability of plant growth was decreased with changes in physiological characteristics. Even in respect of cadmium with high solubility in water and significant uptake in underground organs, have seen stop growing in aboveground plant parts.  Conclusion: In summary results of this research showed that regarding the growth of underground organs, the Pharagmites australis is relatively resistant to cadmium stress, has low transmission factor and ability to accumulate cadmium in its underground organs.