Residual Behavior Of Avermectin And Beta Cypermethrin In Cucumber Field And Its Adsorption In Five Kinds Of Soil Tested

The thesis paper mainly analysises the degradation of abamectin and beta-cypermethrin in cucumber and cucumber soil after the usage of2.8%abamectin and cypermethrin.Meanwhile, it also analysis the adsorption of the beta-cypermethrin in the five different soils. The study statements will be the strong support to evaluate the environmental influence after the uasage of abamectin and beta-cypermethrin in a comprehensive way. It also demonstrates us the scientific way to use the abamectin and beta-cypermethrin in a safe way.Here are the majors conclusions of this thesis paper:(1). The soil and cucumber samples were extrcted with acetonitrile,cleaned-up by salting out method and Florisil column method,and then determined by high performance liquid chromatography(HPLC).The quantification was performed by external standard. The minimum detectable amounts of avermectin was2.0×10-10g,the limit of detection was0.01mg/kg in soil and cucumber.The recoveries of the method ranged from85.06%to91.87%with the relative standard deviations of3.21%-10.90%.This method is suitable for the analysis of pesticide residue.(2). The soil and cucumber samples were extrcted with acetonitrile,cleaned-up by salting out method and Florisil column method,and then determined by gas chromatography electron capture detector(GC-ECD).The quantification was performed by external standard. The minimum detectable amounts of beta-cypermethrin was1.0×10-11g,the limit of detection was0.01mg/kg in soil and cucumber.The recoveries of the method ranged from84.46%to105.82%with the relative standard deviations of4.60%-9.38%.This method is suitable for the analysis of pesticide residue.(3). Study the residual dynamics of avermectin and beta-cypermethrin in soil and cucumber Under the natural condition of Hunan Changsha, Zhejiang Hangzhou and Hebei Shijiazhuang, The results show that the dynamic residual volume of avermectin were lower than0.01mg/kg when avermectin and beta-cypermethrin was sprayed after2h;the degradation of beta-cypermethrin in soil and cucumber meet the requirement of the chemical reaction kinetic equation. Degradation half-live in the cucumber and soil was4.97d～7.13d and3.96d～5.11d.These rusults show that both avermectin and beta-cypermethrin in cucumber field are degradable pesticides.(4). According to the residual quantity of avermectin and beta-cypermethrin residual in cucumber.recommended rational use of3%avermectin and beta-cyperthrin in cucumber. We recommended the reasonable ues standard:the3%avermectin and beta-cypermethrin cream can be used in Liriomyza sativae Blanchard, the maximum dosage is1000g/ha which can not be used more than once. The safety interval is5days.(5). The absorption time for beta-cypermethrin, among one of the five chosen tested soil, was about20to24h. This is in line with the isothermal adsorption model and the Freundlich model. The strongest adsorbability for beta-cypermethrin is when it is used in wet soil of Hunan and in it’s weakest power in the sand soil in Hangzhou which at the same time means the liquidity is better in the Hangzhou soil while the worst liquidity in Hunan soil. The difference of the pH rate has little influence for the absorption of beta-cypermethrin in silt soil and black soil. In the red soil and the river sand soil of Hunan,the PH rate is of great influence for the the absorption of beta-cypermethrin.The elements which matters the most is the CEC. The adsorption capacity of the five chosen tested soil is11.42～13.53kJ·mol-1. The data means the type of adsorption belongs to physical absorption.(6). By observing effection of5kinds of inorganic salt solution in their absorbing beta-cypermethrin for alluvial soil and red soil of Hunan we can get the conclusion that:the inbibitional effect is strong in absorbing beta-cypermethrin for Hunan alluvial soil when it is added with the low concentration of NaNO3, NaHCO3, while the inbibitional effect is weak in absorbing beta-cypermethrin for Hunan alluvial soil when it is added with inorganic salt such as NaCl, KCl, and CaCl2; the inbibitional effect is strong in absorbing beta-cypermethrin for Hunan red soil when it is added with low concentration of KCl, while the inbibitional effect is weak in absorbing beta-cypermethrin for Hunan Red Soil when it is added with inorganic salt such as NaCl, CaCl2, NaNO3and NaHCO3.