Degradation and adsorption characteristics of cyclobutrifluram in multi-media environment

To investigate the degradation, adsorption, and desorption behaviors of the novel fungicide cyclobutrifluram, degradation and adsorption experiments of cyclobutrifluram were conducted under different soil types and water conditions. The results showed that the degradation of cyclobutrifluram in four types of soils followed the first-order kinetic model, with a half-life ranging from 43.6 d to 145 d. Among the influencing factors, anaerobic microorganisms, organic matter, and organic carbon content were identified as the crucial regulators governing its degradation process. The hydrolysis rate of cyclobutrifluram within 5 days ranged from 3.3% to 5.0%, indicating its favorable chemical stability. The photodegradation half-life of this fungicide varied from 10.4 h to 16.0 h, classifying it as a moderately photodegradable pesticide, and the photodegradation rate exhibited an order of neutral condition > alkaline condition > acidic condition. The adsorption kinetics of cyclobutrifluram in the four tested soils were well fitted to the pseudo-first-order kinetic model, with the maximum adsorption capacity rate ranging from 25.1% to 39.4% and the maximum desorption capacity rate ranging from 7.9% to 24.3%. Furthermore, the isothermal adsorption process conformed to the Langmuir model, and the organic carbon adsorption constant was in the range of 444.3-674.7, suggesting that cyclobutrifluram was a pesticide with relatively weak soil adsorption capacity. The groundwater pollution index of cyclobutrifluram varied from 2.9 to 3.3, implying a high leaching potential. In conclusion, cyclobutrifluram is a pesticide with moderate to difficult degradability in the four tested soils, possessing chemical stability in water. Meanwhile, its weak soil adsorption capacity leads to easy leaching, which poses a potential pollution risk to the groundwater system.