Study On Degradation And Residues Of Abamectin In Orangery And Its Photo-degradation In The Aqueous Solution

Abamectin is an effective, Low-poison, green and environmental-friendly acaricide, is widely used on crops such as vegetables, fruit trees and rice etc. In order to evaluate whether the Abamectin used on citrus will endanger the environment, this paper systematically studies the residual and degradation in citrus and gardens’soil. And also studies the light degradation in aqueous solution. In these studies, the safety of ecological environment after using Abamectin were evaluated comprehensively and accurately, which provided valuable basic data for Abamectin’s scientific usage.(1) Established liquid Chromatographic analytical method of residual quantity in citrus gardens and also the methods of collect, extract, refine. For Abamectin, the minimum detectable amount is4x10-11g, and the minimum detection limit concentrations in soil, whole-peeled citrus, citrus flesh and citrus peel is0.01mg/kg. When adding concentration between0.01to1.00mg/kg, the average recovery in deferent citrus fruits is79.1%-104.1%, Standard deviation is1.5%-17.6%.(2) The degradation of Abamectin in soil and citrus obey the first-order equation, the half-time degradation in soil is:GuiZhou6.46d> HuNan6.27d> ZheJiang5.69d, The degradation of Abamectin in whole-peeled citrus is:ZheJiang6.15d>HuNan5.59d>GuiZhou3.96d, the difference between3areas is not so significant, indicated that Abamectin belong to Easy Degraded pesticide in citrus fruits. According to recommended usage rate, used3%Abamectin (1:3000) to spray on tangerines. The residual quantity in citrus flesh after7d,14d and21d of treatment, is capped within LOD-0.009mg/kg; all did not exceed MRL (0.01mg/kg). The residual quantity in citrus flesh is capped within LOD-0.006mg/kg after14d of treatment, and did not exceed MRL (0.01mg/kg). In conclusion, the dosage of3%Abametin EW in citrus is safe to be used.(3) Abamectin in the light of500W high pressure mercury lamp,showing a certain degree of degradation of the half-life in water for31.45min.The dissolved oxygen content of avermectin photodegradation has a minor impact. In the surface water of avermectin fhotodegradation rate performance as the river water>purified water>pond water>water. Cl-compared to NO3-photolysis avermectin show some light quenching. Fe3+higher than of Na+on the photolysis of abamectin showed a certain degree of photosensitization. Sodium humate the avermectin light quenching with the increase in humic acid concentration of sodium,its photolysis quenching effect of avermectins enhanced.Abamectin in several organic solvents,the photochemical degradation rate in the order of dichloromethane>methanol> ethyl acetate.