Study On The Degradation Characteristics Of Atrazine In Soil By Symbiotic Fungi And Alfalfa

Atrazine is the most widely used herbicide currently in China. As a result of its large application, long residue and low degradation rate, atrazine has caused more and more serious soil contamination. Therefore, remediation of atrazine contaminated soil is extremely urgent.Three chamber culture systems are used in this research, Medicago sative inoculated with Glomus mossea(GM) and inactivated GM are respectively considered as the treatment group and the control group. Arbuscular mycorrhizal(AM)- Medicago sative Linn symbiosis could significantly improve efficiency of atrazine degradation, raising its degradation rate from 23.66% to 77.75%.In the treatment group and the control group, root exudate of Medicago sative Linn in the early, medium and late period are respectively collected and extracted. The degradation rate amounts to the highest point in each period when root exudate has been added in 8 mg/L atrazine for 24 hours. The degradation rate of root exudate in early growth period of treatment and control group are 57.25% and 44.87% respectively, degradation rate is 58.38% and 45.88% in medium period, then 50.13% and 40.25% in late period. These results demonstrate that the degradation process of atrazine accelerates when AM is inoculated in Medicago sative Linn, and the effect is more significant in the late period. Furthermore, identified by GC-MS technology, root exudate mainly includes alkanes, alcohol, acids, amino acids, esters, amine, ketone and alkene. The amount and distribution of these elements in root excudate show difference between treatment and control group which may be relevant to the degradation effect of GM inoculated Medicago sative Linn.LC-MS/MS is applied to identify the intermediate metabolite of atrazine degradation, which includes hydroxyl atrazine N-isopropyl ammelide cyanuric acid allophanamide and allophanic acidare. Metabonomics, based on HILIC and RPLC UHPLC-Q-TOF MS technique, is used in metabolic profiling analysis, analyzing samples of Medicago sative root in CK and GM. Then the different metabolites are sent to KEGG website for pathway analysis. The result shows that more different metabolites are found in pathway map01100、map01110、map01060、map01120, and different metabolites plays an important role in degradation of atrazine by AM fungi.Degradation rate is enhanced by using AM fungi- plant combined remediation technology. These results provide theoretical foundation for the development of inoculated AM for remediation of pesticide and protection of ecology and therefore, contributes to soil remediation and ecological protection.