Effect of citric acid on remediation efficiency and antioxidant enzyme of Solanum nigrum L. under Cd and Pb combined pollution
Cd、Pb复合污染下柠檬酸对龙葵修复效率及抗氧化酶的影响

Phytoremediation of soil heavy metals is generally considered as a clean and economical method of bioremediation.In order to improve the efficiency of bioremediation,citric acid as a chelating agent was used to enhance the uptake efficiency of Solanum nigrum L.and to study the changes of its physiological activity in the indoor pot experiment.The results showed that when citric acid’s concentration was 10 nmol/kg,the biomass of Solanum nigrum L.was significantly enhanced(P<0.05),whose orders were as follows: stem>leaf>root.With the increase of the concentration of citric acid,Solanum nigrum L.had remarkably increasing absorption ability for Cd(P<0.05),and the maximum amount of Cd could reach up to 229.85 μg/g DW when citric acid’s concentration was 10 nmol/kg.It is implied that the enrichment factors of Pb and Cd could reach up to their maximum when citric acid’s concentration was 5 nmol/kg.The amount of Pb absorbed increased at the beginning and then gradually declined while critic acid’s concentration was added.It indicated that application of citric acid significantly enhanced the absorption activity for Cd and improved the activity of antioxidant enzymes of Solanum nigrum L.,but the effect of Pb absorbed was not obvious.