Abstract: In order to evaluate the risk of isoxaflutole in the environment, the volatility, absorption and degradation characteristics of isoxaflutol was examined by a laboratory test. The results demonstrated that absorption of isoxaflutole in four soil types (fluvo-aquic soil, paddy soil, black soil and red soil) accorded with Freundlich equation. The calculated adsorption coefficient of isoxaflutole in fluvo-aquic soil, paddy soil, black soil and red soil was 0.640 6, 1.376 2, 0.816 9 and 1.289 5, respectively. The results indicated that isoxaflutole was hardly absorbed in these four soil types. The degradation of isoxaflutole in lake (West Lake) and river (Grand Channel) water-sediment system accorded with first-order kinetic equation. The aerobic degradation half-life period was 73.7 h and 75.3 h, respectively, and the anaerobic degradation half-life period was 42.3 h and 43.0 h, respectively. The results indicated that isoxaflutole was an easily degradable pesticide in water-sediment system .The volatility rate of isoxaflutole in air, water and on soil surface was less than 1% under the conditions of 20-25 ℃ and 500 mL·min^-1 gas flow rate, indicating that isoxaflutole belonged to a difficult volatility pesticide. In general, isoxaflutole possessed the characteristics of difficult volatility, difficult absorption and fast degradation in water-sediment system, and had a relatively low risk to environment.

Key words: isoxaflutole, volatilization, soil absorption, water-sediment system