Aerobic biodegradation kinetics and pathway of the novel herbicide ZJ0273 in soils

Degradation of ZJ0273, a recently developed pyrimidynyloxybenzoic‐based herbicide, was investigated in five different soils under aerobic conditions. ZJ0273 degradation rate was strongly affected by soil physico‐chemical characteristics and the inoculation of ZJ0273‐degrading bacteria. Greater organic matter (OM) content, neutral pH and inoculation of ZJ0273‐degrading bacteria can increase degradation rate and decrease the half‐life value (DT50). At 30°C the biodegradation rate of ZJ0273 reached 41–85% in natural (unsterilized) soils. It ranged from 69 to 96% at 90 days after treatment (DAT) in five different types of soils after re‐inoculation of Amycolatopsis sp. M3‐1 and DT50 decreased by 34 , 81, 16, 20 and 32 days, respectively, in soils S1, S2, S3, S4 and S5. Furthermore, using the six metabolites (M1–M6) identified six metabolites (M1–M6) by liquid chromatography‐mass spectrometry (LC‐MS) and their behaviour, a biodegradation pathway of ZJ0273 in soils was proposed. New metabolites, M5 and M6, were found in soils. Biodegradation of ZJ0273 involved continuous biocatalytic reactions, such as de‐estering, hydrolysis, acylation, C‐N cleavage, de‐methyl and ether cleavage reactions. Finally, ZJ0273 was bio‐transformed into M4 and M6, which could be degraded and oxidized into CO₂ and H₂O through the tricarboxylic acid (TCA) cycle.