Influence of Salinity on Phytoremediation of Cadmium in Contaminated Soils

Phytoremediation is one of the methods used to remove contaminants and while being simple, cheap and efficient, does not cause environmental deterioration. The aims of this study were phytoremediation of soil contaminated by Cd, the simultaneous survey of the influence of different electrical conductivity values, and comparison of two soil amendments including sludge and municipal compost in increasing of Cd uptake by sunflower. Experiments of this study were conducted randomly with three replications in the split plot design consisting of 24 pots from June to August 2010. To determine the effect of salinity on metal uptake efficiency of the sunflower plant, irrigation water was used with different levels of electrical conductivity, in the range of 0, 2, 4 and 6 dS/m. The combined effects of organic amendments including sewage sludge and municipal compost in improving the efficiency of metal uptake was also examined. The most Cd was absorbed in the 6 dS/m EC and in the sludge bed. The EC contents of the root, stem, and leaves were 5.8 ± 0.7, 11.8 ± 3.6 and 8.4 ± 0.0 mg/kg, respectively. It caused dry weight reduction of leaves and the most loss was observed in the treated soil with compost. ANOVA showed that with increasing the EC of irrigation water, the amount of Cd absorbed by the roots, stems and leaves will increase. Cd uptake in the sludge amendment was also greater than soil treated by compost. Thus, EC and sewage sludge applications increase the uptake of cadmium.