Comparative Phytoremediation of Chromium-Contaminated Soils by Alfalfa (Medicago sativa) and Sorghum bicolor (L) Moench

A study was carried out to investigate the potential of alfalfa and sorghum for phytoremediation of soil contaminated chromium. Soil samplings of 0-10 cm depths were taken. The experiment consisted of five treatments in which chromium concentration varied from 0 to 10 mg/kg soil (blank (T1), soil contaminated with 2 mg/kg concentration of chromium (T2), soil contaminated with 4 mg/kg concentration of chromium (T3), soil contaminated with 8 mg/kg concentration of chromium (T4), soil contaminated with 10 mg/kg concentration of chromium (T5). Alfalfa and sorghum were grown for 50 days after seeding in pots containing 5 kg of these soils. Chromium concentrations in soil after phytoremediation by alfalfa were 0.74, 1.16, 2.08,and 4.00 in T2, T3, T4, and T5, respectively. Chromium concentrations in soil after phytoremediation by sorghum were 0.84, 1.36, 2.44, and 5.12 in T2, T3, T4, and T5, respectively. Concentration of chromium in soil in all treatments after phytoremediation by alfalfa was decreased between 60-74%, and after phytoremediation by sorghum was decreased between 51.2-69.5%. The evidence provided by this experiment indicated that alfalfa and sorghum are effective accumulator plants for phytoremediation of chromium, but the potential of alfalfa was more than sorghum for phytoremediation of chromium polluted soils.