Phytoremediation of the soils contaminated with cyanide by Vetiveria zizanioides

In the field of environmental risk assessment, Cyanide is one of the most important pollutants of water, soil and air that has an important impact on the ecosystem and environment of the contaminated area. Therefore, the present study aimed to prove the biological effectiveness of Vetiveria zizanioides in phytoremediation of soils contaminated with cyanide.
This research study was conducted on a gold mine wastewater. The dried effluent samples amended with soil with various cyanide concentrations. Seven treatments with different concentrations of cyanide were obtained (mean cyanide content in G soil, 14.77 mg/kg, F soil, 10.13 mg/kg, E soil, mg/kg 8.09, D soil, mg/kg 7.53, C soil, 3.32 mg/kg, B soil, 2.52 mg/kg and A soil without cyanide (as control). After two months, the amount of cyanide in the soil, roots and leaves of the plant, as well as the total protein and proline content, and the number and length of the leaves of the plant were measured and then statistically evaluated by SPSS15 Tukey and t Paired Samples T Tests.
The results of this study showed that the increase of cyanide had a significant effect on the amount of proline (proline in the plant increased), total protein (in the plant increased), number of leaves (decrease in number) and the length (length reduction) of the leaves of the vetiver. The amount of cyanide in the leaves and roots of the plant was increased. Cyanide content was decreased in the different treatments. Cyanide content was decreased in G 50.93%, F 38.20%, E 27.19%, D 38.37%, C 17.77% and B 16.66%.
The results indicated that increase of the amount of cyanide in soil resulted in observational changes in the morphological and biochemical characteristics of the plant. However, Vetiveria zizanioides exhibited very high resistance to soil cyanide and the planting of vetiver in highly contaminated soils can lead to a reduction of cyanide up to 50 percent. Vetiveria zizanioides had higher resistance to cyanide and showed better phytoremediation than the other plants.