Absorption and Transport of Heavy Metals Copper and Cadmium in Alfalfa from Vanadium-titanium Magnetite Tailings

Phytoremediation technology is widely used in ecological restoration process of abandoned mines, and the ability of plants to absorb heavy metals should be taken into account. In order to explore the absorption characteristics of Cu and Cd in the tailings of vanadium-titanium magnetite by the restoration plant alfalfa, Cu and Cd were added externally to the tailings to simulate different pollution levels. After three months, the occurrence forms of Cu and Cd in vanadium-titanium magnetite tailings, the growth of alfalfa and the absorption and transport of Cu and Cd in alfalfa were analyzed to study the absorption and transport characteristics of alfalfa under Cu and Cd stress. The results showed that after three months, Cu mainly existed in acid-soluble form and Cd mainly existed in oxidizable form, the ecological risk was relatively high. The addition of Cu could inhibit the emergence and shoot growth of alfalfa, but the uptake of Cu by alfalfa increased significantly. The uptake of Cu by the shoot and the ground increased by 1.78%～109.62% and 48.46%～463.11%, respectively. The shoot was the main enrichment site of Cu. Cd was mainly accumulated in the roots of alfalfa. With the increase of Cd stress concentration, the ability of alfalfa to transfer Cd from root to shoot increased. The results can provide a theoretical basis for the study of phytoremediation technology in mining areas.