Abstract

Heavy metals can be absorbed by living organisms, such as aquatic plants or non-living biomass. Aquatic plants can be used for removing heavy metals and nutrients from industrial and municipal wastewaters. This paper investigates the capability of Phragmites australis, Typha latifolia and Scirpus (Bulrush) to uptake arsenic and mercury from industrial wastewater. The accumulation capacities of these aquatic plants in three treatments consisting of 50, 100 and 200 mg/kg As and Hg in soil were studied under the semi-arid conditions of Dezful, Southwest Iran. Data observed from the treatments 60 days after growth indicated that each three species were capable to uptake As and Hg from the solution. Results showed significant statistical differences in accumulation of As in the below-ground tissues of three plants where the highest As accumulation (measuring 119.55 mg/kg) was observed for P. australis in the treatment of 200 mg/kg As in soil, followed by 65.25 and 47.86 mg/kg for Bulrush (Scirpus) and T. latifolia, respectively. Maximum accumulation for Hg in below-ground tissues was observed in P. australis measuring 6.23 mg/kg in 200 mg/kg Hg in soil treatment, followed by Bulrush (Scirpus) and T. latifolia measuring 2.23 and 1.45 mg/kg, respectively. The results indicated that As and Hg accumulations in below-ground tissues were higher than those for the above-ground tissues for all plants. The results also indicated highest below-ground to above-ground tissues rations (BG/AG) for As and Hg in P. australis and Bulrush (Scirpus) ranging 85.3 to 108.8 and 19.7 to 39, respectively. Data obtained from this research conformed well to the exponential association model. The overall conclusion being that the three aquatic plants selected in this study can be used as effective catalysts for removing heavy metals from the industrial wastewater under arid and semi-arid conditions.

Key words: Accumulation, arsenic, mercury and Phragmites australis.