Studies On The Environment Behavior Of Strobilurin Fungicide

Agricultural soils in China mainly include the southern red yellow soil,loess soil,the arid area soil,the northeast forest steppe soil and paddy soil.The physicochemical properties of the organic matter content,viscosity content and acid basicity of soil are very different.The adsorption characteristics of the agricultural chemicals are different,leading to different combinations with the target and soil.Strobilurin fungicide is one kind of fungicide with the development potential and market share.The extensive use of strobilurins makes a major concern on environmental problems.So the analysis method of the strobilurin fungicides,including coumoxystrobin,tricyclopyricarb,picoxystrobin,fluoxastrobin,trifloxystrobin,e-metominostrobin,kresoxim-methyl,dimoxystrobin,fenaminstrobin,pyraoxystrobin and fenaminstrobin,in the soil will be one importent factor of the environmental behavior and safety assessment.The main contents are as follows:1.A method for the simultaneous determination of 11 strobilurin fungicides including coumoxystrobin,tricyclopyricarb,picoxystrobin,fluoxastrobin,trifloxystrobin,e-metominostrobin,kresoxim-methyl,dimoxystrobin,fenaminstrobin,pyraoxystrobin and fenaminstrobin,in different types of soil by quick,easy,cheap,effective,rugged and safe(QuEChERS)-ultra performance liquid chromatography-tandem mass spectrometry.The strobilurin fungicides were extracted with 0.1%acetic acid-acetonitrile,and cleaned-up by primary secondary amine and C18.The separation was performed on a C18 column with methanol and water as the mobile phase.The strobilurin fungicides were determined by the mode of positive ion mode and multiple reaction monitoring.The quantification was carried out by matrix-matched external standard curve.The main results are as follows:The linear of strobilurin fungicides in the concentration range of 0.1-100 μg/kg,and the correlation coefficient was 0.9805-0.9999.The recovery of blank samples at concentration of 5 and 50 was 65.1 to 103.9%,respectively.The relative standard deviation(n = 5)was 0.2 to 13.1%.The method was limited to the minimum addition concentration of 5μg/kg,which could satisfy the requirement of the trace detection of 11 methoxyacrylate sterilant in different vegetation type soil,such as black soil,red soil,paddy soil,moisture soil,desert soil and plateau soil.2.The adsorption characteristics of strobilurin fungicides in 6 soils were studied by batch equilibrium method.The results showed that the adsorption kinetics equilibrium time of 11 strobilurin fungicides was 24 h in the 6 soils.The isothermal adsorption curves in 6 soils were well in accordance with Freundlich model.Coumoxystrobin,tricyclopyricarb,picoxystrobin,fluoxastrobin,pyraoxystrobin,kresoxim-methyl and trifloxystrobin were easily adsorbed in the 6 soils,while e-metominostrobin,dimoxystrobin,orysastrobin and fenaminstrobin were not.The adsorption free energy of the soil to strobilurin fungicides is |△G |>40 kJ · mol-1 showing that the adsorption of strobilurin fungicides belonngs to chemical adsorption.The adsorption of coumoxystrobin,trifloxystrobin and orys’astrobin in moisture soil in hebei province belongs to exothermic reaction,while 11 other strobilurin fungicides belongs to exothermic reaction.The adsorption of coumoxystrobin,e-metominostrobin,orysastrobin,pyraclostrobin,dimoxystrobin,and tricyclopyricarb adsorption in the sandy soil in hainan province and the gray desert soil in xinjiang municipality belongs to the exothermic reaction.The adsorption of e-metominostrobin and orysastrobin is a heat-absorbing reaction in black soil in jilin province.Adsorption of e-metominostrobin by soil in qinghai province belongs to endothermic reaction.3.The photodegradation behavior of e-metominostrobin,dimoxystrobin,orysastrobin and fenaminstrobin in water were studied under the condition of simulated solar illumination.The half-lifes and the degradation rates of these four fungicides in water were calculated.The safety of these four fungicides in the environment was also predicted.The photodegradation in water of e-metominostrobin,dimoxystrobin,orysastrobin and fenaminstrobin were in accordance with the first order reaction kinetics equation,the half-life times of these fungicides were 9.7 h,3.6 h,9.1 h and 9.5 h,respectively.The order of degradation rate of the four fungicides is the fenaminstrobin>orysastrobin>dimoxystrobin>e-metominostrobin.Based on above results,the following conclusions are:(1)This method is simple,fast and efficient,with good reproducibility,high sensitivity and good linear relationship,which could be applied on the trace analysis of 11 methoxylmethacrylate fungicides in different soil types.(2)Organic matter content and structure of soil have an impact on adsorption behavior of strobilurin fungicides.(3)According to the photodegradation half-life of those fungicides,fenaminstrobin was easy photolysis,and e-metominostrobin,dimoxystrobin,orysastrobin were the medium photolysis substance.