摘要
为预测和评价双氟磺草胺对水资源及土壤环境的潜在风险提供依据,采用室内模拟试验方法,研究双氟磺草胺在不同土壤(黑土、红壤和水稻土)环境中的降解、吸附、淋溶以及在土壤表面的挥发性和光解性等归趋特征。结果表明:双氟磺草胺在吉林黑土、云南红壤与贵州水稻土中的降解符合一级动力学方程,其在3种土壤中的降解半衰期分别为12.8d、15.0d和12.6d,属于易降解农药;双氟磺草胺在3种土壤中的吸附符合Freundlich方程,Kd值(吸附常数)分别为1.83、1.14和0.537,3种土壤中均难吸附。经土壤薄层层析试验,当溶剂展开18cm时,双氟磺草胺在吉林黑土、云南红壤与贵州水稻土中主要分布在12~18cm、9~18cm和9~18cm土层中,其Rf值(比移值)均为0.917,极易移动。双氟磺草胺在土壤表面光解遵循一级动力学方程,Ct=4.355 8e-0.002 t,光解半衰期为346.5h,属于难光解农药。在(25±2)℃,气体流速为500mL/min的条件下,双氟磺草胺在土壤表面的挥发速率小于0.04%,属于难挥发农药。双氟磺草胺在土壤中难挥发、难光解、难吸附、易移动,但其在土壤中降解较快,对土壤环境的风险性小。
The degradation,absorption,leaching,volatility and photolysis characteristics of Florasulam in three soil types of black,red and paddy soils was analyzed by an indoor simulation test to provide the scientific basis for forecast and evaluation of Florasulam potential risk in water resource and soil environment.Result:The degradation of Florasulam in three soil types accords with first-order kinetic equation and the degradation half-life period of Florasulam in black,red and paddy soils is 128 d,15.0 d and 12.6 drespectively,which indicates that Florasulam is an easily degradable pesticide.The absorption of Florasulam in three soil types accords with Freundlich equation and the Kdvalue of Florasulam in black,red and paddy soils is 1.83,1.14 and 0.537 respectively,which indicates that Florasulam is hardly absorbed in three soil types.The TLC analysis shows that Florasulam mainly distributes in black soil with 12-18 cm depth,red soil with 9-18 cm depth and paddy soil with 9-18 cm depth respectively when the solvent expands to 18.0 cm and their Rf value is 0.917,which indicates that Florasulam is an easily movement pesticide.The photolysis of Florasulam on soil surface follows first-order kinetic equation and the Ctand photolysis half-life period are 4.355 8 e~(-0.002 t) and 346.5 hrespectively,which indicates that Florasulam belongs to a difficult photolysis pesticide.The volatility rate of Florasulam on soil surface is less than 0.04% under the conditions of(25±2)℃ and 500 mL/min gas flow rate,which indicates that Florasulam belongs to a difficult volatility pesticide.Florasulam with the characteristics of difficult volatility,difficult photolysis,difficult absorption,easy movement and faster degradation in soil has a lower risk to soil environment.
引文
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