Assessing some shrub species for phytoremediation of soils contaminated with lead and zinc

The objective of this research is to study the effects of refinery effluent of Alborz Industrial City (Iran) on the soil and plant growth including Robinia pseudoacacia, Cercis siliquastrum, and Caesalpinia gilliesii. Firstly, samples were taken from soils irrigated with wastewater. The results of initial soil test revealed that the concentrations of Pb and Zn in the agricultural soils irrigated with treated wastewater showed significant differences (P < 0.01). The highest concentrations of Pb and Zn in the agricultural soils irrigated with treated wastewater and in the vicinity of industrial sites were 49.91 and 85.62 mg/kg, respectively. Secondly, the effect of wastewater treatment on the absorption of heavy metals by plant species was studied under greenhouse conditions. Treatments included four levels of effluent (100, 50, 25, and 0%) and three plant species. At the end of the experiments, concentrations of Pb and Zn in the soil and in the plant organs were measured. The results showed that there were significant differences between metal concentration in the soil and in the plant roots and shoots. Under 100 and 50% of industrial wastewater, R. pseudoacacia and C. gilliesii had the highest efficiency regarding RFZn (remediation factor), TFPb (translocation factor), BCFZn, and BCFPb (bioconcentration factor). Overall, two species of R. pseudoacacia and C. gilliesii had the highest Pb concentrations (15 and 32 mg/kg) in the shoots and thus have the ability to remediate contaminated soils. Therefore, they can be an appropriate choice for the phytoremediation of Pb-contaminated soils.