Response of Urease Activity to Zn in Sewage River Sediment under Different Phytoremediation Methods

The phytoremediation of heavy metals in sewage river sediment in a coastal city was investigated by single phytoremediation method,EDTA-induced phytoremediation method and plant-mycorrhizal fungi phytoremediation method.The plants used were maize,ryegrass,Indian mustard and Medicago sativa L.The change in urease activity and its relationship with zinc concentration in sediment under different phytoremediation methods were analyzed.Urease activity in soil under different plant combinations,treatment levels and treatment lengths were monitored.The results showed that the removal rate of Zn by maize under the EDTA-induced phytoremediation method was the highest at 69.00%.The removal rate of Zn by ryegrass under the plant-mycorrhizal fungi phytoremediation method was the second highest at 64.37%.Taking a comprehensive consideration,the plant-mycorrhizal fungi phytoremediation method is more suitable for remediation of sediment and soil contaminated by Zn.Plants suitable for remediation of sediment contaminated by Zn were maize and ryegrass.The urease activity in root soil during the remediation by ryegrass was the highest,and the uptake of Zn by maize was the highest.Low temperature had great influence on urease activity,and the absorption of zinc by plants should be avoided.