| The characteristics of adsorption and migration in soil and degradation in water of fluxapyroxad were studied by simulation experiment.(1)The method for determining fluxapyroxad was optimized.The accuracy and precision of method met the requirements of pesticide residue analysis.In the range of 0.05~100 mg.L-1,the linear correlation was 0.9999.When the addition level was 0.1 ~1.0 mg.L-1 in water,the recovery ratio of fluxapyroxad was 81.21% to 84.56% and the relative standard deviations was 0.38% to 0.85%.Meanwhile,the addition level of 1.0~10.0 mg.kg-1 in soil,the recovery ratio was 81.76% to 101.26% and its relative standard deviation was 0.71% to 4.27%.(2)The adsorption of fluxapyroxad in soil conformed to pseudo-2nd-order kinetics.The process consists of two stages,the first adsorption rate was greater than the second.Under the initial concentration of 0.5 mg.L-1,the KWM of two stage were 0.753,0.213 in yellow soil,and 0.456,0.160 in the purple soil.(3)Fluxapyroxad was weak adsorption in yellow soil and purple soil.The Kf-ads value of Freundlich model were 7.276 and 3.437,and the KOM were 25.008 and 11.814.Hysteresis effect existed in desorption,the hysteresis coefficient of was 0.990 and 0.903.(4)According to the “Experimental Guideline for Environmental Safety Evaluation of Chemical Pesticide”,the mobilities of fluxapyroxad in soil were middle level,the Rf was 0.322 to 0.472.(5)The degradation of fluxapyroxad in water conformed to first-order kinetics,and carried on more easily in neutral condition.At 25?,the half lives of pH 4,7,9 were 81.7,35.3,and 55.8 d.The degradation rate increased with temperature.At pH 7,the half-life of 5?,25?,35? were 101.2,42.2,25.8 d.Weakly adsorption,easily migration,difficulty degradation of fluxapyroxad may cause potential environmental risks. |
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