| Nowadays,pesticides have been widely used in modern agriculture and played an important role in modern agriculture,especially played an important role in preventing and controlling plant diseases and pests during the process of vegetable production.However,the pesticide residue problems caused by the improper use seriously that affectted the quality of the vegetables.It is urgent to study degradation patterns and influence factors of pesticide residue.The paper aims to study environmental pollution and pesticide residue level which caused by the application of clothianidin and hexaflumuron in the field of chive,and the distribution of clothianidin in different parts of chives,and effect of precipitation and ultraviolet ray on the degradation of clothianidin.These studies will solve the problem of pesticide residues and complete the trace standard of pesticide in chives.Residues of clothianidin and hexaflumuron in samples were extracted with acetonitrile and removal of sulfur-containing compounds with phosphoric acid,cleaned up with Florisil column and determined by high performance liquid chromatography(HPLC)with UV-detector.The minimum detectable amount of clothianidin and hexaflumuron was 0.071 and 0.134 ng respectively.For the chives and soil samples,the minimum detectable concentration of clothianidin and hexaflumuron was 0.24 and 0.45 μg/kg respectively,the average recoveries were 87.64%~107.67% and 91.62%~92.70% respectively and the coefficient of variation were 3.92%~6.44% and 3.92%~6.44% respectively.The minimum detectable concentration of hexaflumuron was 0.45 μg/kg in chives and soil samples,the average recoveries were 88.45%~93.82% and 91.21%~91.93% respectively and the coefficient of variation were 2.55%~3.61% and 1.73%~3.64%.These results illustrate the methods of residue analytical satisfy the requirements of pesticide residues.Digestion dynamics of 30 % clothianidin·hexaflumuron SC: field experiments were conduct to study the degradation dynamics of clothianidin and hexaflumuron in chives and soil.The field trials choose conduct in Guangdong and Hubei province.In chives and soil,the half-life of clothianidin was 6.30~8.77 d and 4.08~ 4.95 d,respectively,and the half-life of hexaflumuron was 3.94~5.37 d and 4.17~6.73 d,respectively.The test of 30 % clothianidin·hexaflumuron SC final residue: in field experiment,1 time(675 g.a.i./ha)and 2 times(1350 g.a.i./ha)of the recommended dose were root-irrigated in chive and soil for 2~3 times.The result in two places shows that both maximum residual amount of clothianidin and hexaflumuron in chives are lower than the value of International maximum residual amount.Digestion dynamics of 48% clothianidin SC: field experiments were conducted to study the degradation dynamics of 48% clothianidin SC residues in chives and soil.The field trials were conducted in Guangdong and Hubei.In chives and soil,the half-life of clothianidin was 5.50~6.54 d and 4.59~4.03 d,respectively.The test of 48 % clothianidin SC final residue: in field experiment,1 time(675 g.a.i./ha)and 2 times(1350 g.a.i./ha)of the recommended dose were root-irrigated in chive and soil for 2~3 times.The result in two places shows that both maximum residual amount of clothianidin and hexaflumuron in chives are lower than the value of International maximum residual amount.The paper aims to study the space-time distribution of clothianidin in chives under field experiments,The results show the content of clothianidin in soil cauloid was highest and the content of clothianidin in leaf was lowest.The varying patterns of the degradation rates are as follows: cauloid > fibrous root > soil cauloid > bulb > leaf > rootstocks.According to results of this study,we can see that precipitation and excessive ultraviolet ray will affect the absorption and transmission of clothianidin in chives.In order to ensure good efficacy and less pesticide residue,we must grasp the right time of pesticide application in actual production. |
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