Effect of Eisenia foetida on the metal uptake by Sedum plumbizincicola in different types of contaminated soils

Abstract:

Sedum plumbizincicola is a native cadmium/zinc (Cd/Zn) hyperaccumulator in China. At present, it has been applied to remediation of Cd contaminated soils. As the large differences in the removal efficiency of Cd and Zn for different soil conditions, the enhancement measure is important for the phytoremediation process. There have been many studies on the effects of earthworms on plant growth. But the effects on the growth of S. plumbizincicola and heavy metal removal efficiency have been rarely reported. There were 2 pot experiments: S. plumbizincicola was planted on 3 types of soils: Perudic Luvisols, Stagnic Anthrosols, and Udic Cambisols inoculated with Eisenia foetida to explore the effect of Eisenia foetida on the growth and Cd/Zn absorption of S. plumbizincicola. Stagnic Anthrosols with higher Cd effectiveness was selected in the second season pot experiment for further research the combined effect of earthworm and rich straw. The results of the first pot experiment showed that the addition of earthworms in acidic Perudic Luvisols increased the shoot biomass of S. plumbizincicola by 106% compared with the control treatment, and the Cd and Zn uptake increased by 72.0% and 36.0%, respectively. The soil available Cd was reduced by the addition of earthworms. The other two soils inoculated with earthworms had no enhancement on phytoremediation, addition of earthworms together with straw could improve the growth of S. plumbizincicola and the Cd/Zn uptake in Stagnic Anthrosols. The above results indicated that adding earthworm can enhance the phytoremediation of Cd/Zn hyperaccumulator, and the addition of straw is an important synergistic technique for earthworm-enhanced phytoremediation of S. plumbizincicola.