Phytoremediation of cadmium, lead and zinc by Medicago sativa L. (alfalfa): A study of different period

Medicago sativa L. (alfalfa) has been reported to be extremely resistant to contaminants as well as a bioaccumulator. However, heavy metals accumulated by alfalfa in different period was less analyzed and reported. In the present experiment, the alfalfas grew for 10 days, 40 days and 80 days in different soils which were polluted by Cd, Pd, and Zn. It was found that: alfalfa could be applied for phytoremediation of soil polluted moderately by Cd, Pb, and Zn. Alfalfa could transfer heavy metals from roots to shoots in seedling period. Alfalfas had the higher biomass in maturation period. However, biomass of alfalfa was not significant difference in the same period. In different period, alfalfa showed the similar ability of accumulating Cd, Pb and Zn in roots and shoots. Compared with the shoots, the contents of Cd, Pb and Zn in the roots were higher. BCF (bioconcentration factor) values of alfalfa in Cd, Pb and Zn were higher in maturation period. Alfalfa had a better ability of accumulating Cd. TF (translocation factor) values of alfalfa were low and tended to decrease with the increasing contents of Cd, Pb and Zn in the soils.