The Mobility And Degradation Of Xiaochongliulin In Soils

Xiaochongliulin,invented by Sichuan Academy of Chemical Industry Research and Design,is an organophosphorous insecticide and acaricide,which is effectively against a wid range of insects, especially the citrus arrowhead scale.At present,the pesticide has been temporarily registered to control citrus arrowhead scale in China.However,the environmental behavior of it in soil have not been reported in home and abroad.Therefore,the studies on these are of great significance.The main environmental behaviors of Xiaochongliulin,including absorption,desorption,mobility and degradation,were studied.The main results were summarized as follows:1.HPLC of XiaochongliulinA method was developed for determination Xiaochongliulin residues in soil by HPLC. Chromatographic column Venusil C18 250 mm×4.6 mm,was used for analysis.220nm was choosed for UV wavelength,flow liquid were water and acetonitrile.The peak time is 6.69 min.Under the optimize condition for residues,average recveries of xiaochongliulin from soil were in the range from 98.4%～100.2%,the coefficient of variaon was 0.515,which accord with qualification of CIPAC.2.Adsorption-desorption characters of Xicaohongliulin in 6 type of soilsThe adsorption-desorption experiments of the pesticide in soils were conducted by the batch equilibration and HPLC techniques.The results showed that the different adsorption ability of xiaochongliulin was found in 6 tested soils with different physical and chemical properties,and the free energy of adsorptions indicated the spontaneity of the given adsorption process of the pesticide in soils and unreversed adsorption existed during the process.The adsorption-desorption isotherms of the pesticide in the tested soils was fitted with Frendlich equation well.Furthermore,the difference of adsorption capability occurred in different soils to the pesticide.Among all tested soils, the Sichuan gray brown soil had strongest affinity with herbicides,and the Chongqing purple soil had weakest affinity with herbicides.Further linear regression analysis showed that the product of Frendlich constants of adsoprion,K_ads-f(1/n_ads),had a positive correlation with organic matter content(OM%) and clay content(Clay%),but negative correlation with pH value of soils.The results of desorption indicated that the hystersis phenomena appeared during desorption process for the herbicides in tested soils mostly. 3.Mobility of Xiaochongliulin in 6 type soilsThe mobility of xiaochongliulin in three kinds of soil was studies by the soil thin layer chromatography(TLC).This experiment showed that the pesticide were more mobile in soils with lower content of OM%and Clay%than in soil with higher and there was a close relationship between the mobility of the pesticide and the properties of soil.Xiaochongliulin don't move in the Sichuan gray brown soil and Guangxi red soil,don't easily move in the other for soils.4.Degradation Dynamics of Xiaochongliulin in soils and its Influencing FactorsDegaradation dynamics of Xiaochongliulin in four soils were investigated under labrotory condition to understand effects of soil properties on degradation.Results showed that the degradation of Xiaochongliulin in soils followed the first-order kinetic equation,the degradation rate constant(k) varied from 7.21×10^-2 to 11.63×10^-2,and the half-time ranged from 6.0d to 9.6d.The half-time of degradation decreased with the increase of the percentage of organic matter and soil pH. Microorganisms had a significant influence on the degradation.The degradation rate was also affected by the concentration of added insecticide and environmental factors as temperature, moisture and insecticide concentration,the degradation rate also increased.Xiaochongliulin belongs to readily degraded insecticide.The degradation of Xiaochongliulin is influenced by the percentage of organic matter,soil pH,added insecticide concentration and environmental factors.