Study On The Residue Of Chlorfenapyr In Field And Its Toxicity Effects

Chlorfenapyr is an aryl-substituted pyrrole compounds insecticide and acaricide, which successfully developed through the transformation of the chemical structure of the aryl pyrrole antibiotics. Chlorfenapyr residues in crops and the environment of soil dynamics had been some researches,but studies on residues degradation behavior and toxicity in field have not been reported.In this paper,the residue degradation of chlorfenapyr in paddy and its toxic effects have been studed, provided a scientific basis for the evaluation of the chlorfenapyr water emulsion in the rational use of paddy fields as well as its environmental safety.The main contents of paper were as follows:(1) Established an analytical method of residue analysis of chlorfenapyr in paddy water, soil, straw, rice hull and brown rice,and made a series of tests on samples of the former to deal with the analysis in the process of extraction and purification methods. Samples were extracted with acetone(or acetonitrile),extraction using dichloromethane, purified coupled with activated carbon and neutral alumina,detected by gas chromatography.Minimum detectable of chlorfenapyr was2.0×10-12g,detectable limits of chlorfenapyr residue in paddy water, soil, straw, rice hull and brown rice were0.0001mg/L,0.0005mg/kg,0.001mg/kg,0.001mg/kg,0.0005mg/kg. The result shows that gas chromatography with ECD detection,the parameters such as accuracy, repeatability and precision et al for the method are good to satisfy the basic requirements for pesticide residues detection.(2) The study on the degradation dynamics of chlorfenapyr in field.The result shows that the degradation of chlorfenapyr accorded with Ct=C0e-kt in paddy water,soil and plant;The average half-life of chlorfenapyr of Changsha,Hangzhou and Nanning were5.71days in paddy water,9.20days in paddy soil and8.55days in paddy plant.Thus, chlorfenapyr is a easy degradation pesticide.(3) chlorfenapyr was applied under recommended and high dose,the final residue experiment of chlorfenapyr sprayed interval of7days in rice. After the last application of the14d,21d and28d were collected from the rice plant and paddy soil.Under recommended dose,the residue of straw was0.111mg/kg,rice hull was 0.089mg/kg,brown rice was0.009mg/kg.So chlorfenapyr15%EW in paddy field applied under the recommended dose was safe.It suggested that the MRL of chlorfenapyr in paddy field was0.2mg/kg.(4) A satic experiment has showed that the study of the acute toxicity and joint toxicity of chlorfenapyr, Cu2+、Cr6+、Mn2+to misgurnus anguillicadatus.The results of the acute toxicity indicate that:24～96h LC50of chlorfenapyr, Cu2+, Cr6+, Mn2+were3.5880～9.0207mg/L,0.4698～0.8839mg/L,116.9401～241.1734mg/L,3367.7074～4769.8563mg/L.The safy concentration of them were0.6170,0.1922,112.6459,939.8097mg/L.The joint toxicity of chlorfenapyr and Cu2+for24h was synergism,48～96h were antagonism; The joint toxicity of chlorfenapyr and Cr6+for96h were antagonism; The joint toxicity of chlorfenapyr and Mn2+for48h were antagonism,but at72～96h were synergism.