Study On The Residue Dissipation Dynamics Of Florasulam In Wheat Field And Its Adsorption,Leaching Behavior In Soil

Behavior of pesticides in the environment including dissipation,adsorption,migration,etc,it's a variety of complex physical,chemical and biological process.We can learn about the presence status and behavior of pesticides in the environment through the research,as an important indicator of environmental safety evaluation of pesticides.Florasulam is an new and efficient herbicide belongs to the triazolopyrimidine sulfonanilide family of herbicides,reports of its behavior in environment were few.This article has researched the dissipation dynamics of florasulam in wheat plant and soil,absorption,leaching behavior and its influencing factors in soil in laboratory,which could be the evaluation of the safety of florasulam in the environment and provide the scientific basis for rational administration.The main research contents and conclusions were as follows:Method for the analysis of florasulam residues in wheat plant and soil was established.The recovery experiment was conducted by carrying out 5 consecutive extractions?n=5?of spiked matrices?wheat plant and soil?at different levels?0.01⁰.5mg/kg in wheat plant,0.005⁰.05mg/kg in soil?,the recoveries of florasulam in wheat plant were ranged from90.4% to 115.0%,and RSDs were ranged from 2.0% to 3.9%,the recoveries of of florasulam in soil were ranged from 86.3% to 112.8%,and RSDs were ranged from 2.0%to 4.1%,the detected limit of UPLC-MS/MS for florasulam was 1×10^-11 g,the minimum detectable concentration of florasulam in wheat plant and soil was 0.01mg/kg and0.005mg/kg.The results demonstrated that the approach established was suitable and repeatable for the determination of florasulam residues in wheat plant and soil.The results of residues dissipation dynamics of florasulam at three wheat fields in two years showed that the dissipation dynamics of florasulam for wheat plant and soil could be described by the first-order kinetic equation.The dissipation half-lives for florasulam in wheat plant were ranged from 1.33 days to 5.59 days,and half-lives of florasulam in soil were ranged from 5.66 days to 7.84 days.Method for the analysis of florasulam residues in samples of adsorption and leaching experiments was optimized,the recovery experiment showed that the recoveries of florasulam in soil were ranged from 78.0% to 92.7%?0.5⁵mg/kg added?,and RSDs were ranged from 2.4% to 4.4%,the recoveries of florasulam in water were ranged from 97.3%to 98.8%?0.5⁵0mg/L added?,and RSDs were ranged from 0.5% to 1.2%,the minimumdetectable concentration of florasulam in soil and water was 0.5mg/kg and 0.5mg/L.The results also demonstrated that the method optimized was suitable and repeatable for the determination of florasulam residues in adsorption and leaching experiments.The adsorption of florasulam in three different soils was conducted by batch equilibrium experiment.The results showed that the adsorption of florasulam in the tested soils was better fitted by the empirical Freundlich adsorption isotherm,the adsorption constants?Kf?in Anhui clay,Shandong sandy loam and Henan sandy clay loam were ranged from 0.39 to 0.62,the organic carbon partition coefficients?Koc?were ranged from66.91 to 81.35,showed that florasulam was rather difficult to be adsorbed on tested soils,the values of adsorption free energy??G?in three soils were ranged from-10.90 to-10.42kJ/mol,the adsorption belonged to spontaneous and physical process.The migration of florasulam in three different soils was conducted by column leaching experiment under laboratory conditions,its influencing factors,the initial amount of florasulam and humic acid were also studied with Anhui clay.The results showed that the leaching rates were ranged from 71.7% to 74.1% in three tested soils,florasulam showed comparatively high mobility and leaching degree.The initial addition and humic acid had some effect on leaching rates,thus attention should be paid to pollution problem of groundwater caused by florasulam.