[Establishment and growth of Lolium multiflorum for phyto-remediation of Pb/Zn tailings].

Following the cropping of Sesbania rostrata, Lolium multiflorum was cropped as the subsequent species on an acidified Pb/Zn tailings site. As the experimental treatments, S. rostrata issues harvested on the site were removed from the site or buried into the tailings as the green manure. Changes of tailings chemical and physical properties, germination, growth and heavy metal accumulation of Lolium multiflorum were investigated. The results showed that cropping of S. rostrata improved the chemical and physical properties of the tailings, especially for the contents of organic matter, total nitrogen, available phosphorus and available potassium. The strong acidity (pH < 3) in the Pb/Zn tailings was the main factor that limited the establishment of L. multiflorum. The tailings acidity was decreased temporarily by lime application and it seemed to be helpful only for the germination because the strong acidity was restituted in the end of the experiment. In the most cases, L. multiflorum succeeded to germinate, grow and establish on the Pb/Zn tailings, and yielded relatively great biomass (DM 1.4-3.2 t.km-2). Compared to CK (without S. rostrata cropping), cropping S. rostrata increased the biomass of subsequent L. multiflorum by 4.8%-39.5% in case without S. rostrata green manure using and by 7.7%-139.5% in case with the green manure using, and the green manure application resulted in 2.7%-75.8% increment of L. multiflorum biomass. The results proved that the artificial vegetation process using S. rostrata and subsequent L. multiflorum would be a successful pioneer stage for restoration of the Pb/Zn tailings.