Study On The Environmental Behavior Of Cyhalodiamide

Cyhalodiamide is a novel insecticides developed by Zhejiang Research Institute of Chemical Industry Co.,Ltd,independently.In this paper,a method was established for the detection of cyhalodiamide in soil and water,investigated cyhalodiamide of hydrolysis,photolysis,soil degradation trends and the adsorption-desorption effects in soil.The results could be used to guide the use and evaluate the environmental safety of cyhalodiamide.The main conclusions are as follows:An analytical method was established for the detection of cyhalodiamide in soil and water.The water sample was extracted with methylene chloride and the soil sample was ultrasonically extracted with acetonitrile,purified by PSA(primary secondary amine)and C18,and detected by high performance liquid chromatography(HPLC).The results showed that the linearity of the method was good in the linear range of 0.1-10.0 mg/L,the correlation coefficient(R~2)was 0.9999,and the limit of quantification is 0.01 mg/kg and 0.02 mg/kg in water and soil,respectively.At the three spiked levels of 0.1,1.0 and 5.0mg/kg,the average spike recovery was 87.3%～97.4%,and the relative standard deviation(RSD)was 3.5%～8.2%.The kinetics of hydrolysis of cyhalodiamide was studied in different p H buffer and temperature under the laboratory condition and hydrolysis rule of cyhalodiamide aqueous solution under natural conditions was investigated.The results showed that,the hydrolysis rate of cyhalodiamide is p H9>p H5>p H7 in different p H buffer at 25℃.The hydrolytic rate of cyhalodiamide increased with the increasing temperature between 25～50℃.The degradation of cyhalodiamide in natural conditions is a combination of hydrolysis,photolysis and other factors,and its degradation rate is greater than the hydrolysis rate under the laboratory conditions.The effects of different light sources,p H,water,organic solvent and initial concentration on the photolysis of cyhalodiamide were studied.The results showed that the photolysis rate of cyhalodiamide fits first-order kinetic equation under UV lamp and fluorescent lamp,and the photolysis rate under UV lamp was faster than that in fluorescent lamp.The photolysis rate of cyhalodiamide in alkaline and acidic conditions was faster than that in neutral conditions.The photolysis rate of cyhalodiamide in different water showed the following order:rice field water>distilled water>tap water.The photolysis rate of cyhalodiamide in different organic solvent showed the following order:acetonitrile>methanol>acetone.The photolysis rate of cyhalodiamide was decreased with increasing initial concentration.The degradation half-lives of cyhalodiamide in Henan soil,Chongqing soil,and Guangdong soil were 46.2 d,38.5 d,and 30.1 d,respectively,while in those three sterilized soils,The degradation half-lives of cyhalodiamide was 69.3 d,63.0 d,and 53.3 d,respectively.Both organic matter content and soil microorganisms can affect the soil degradation rate of cyhalodiamide.The adsorptions capacity of soils to cyhalodiamide accorded with Freundich equation,adsorption constants K_d were 5.132,7.501 and 9.734,respectively,and the adsorption capacity of cyhalodiamide for three soils showed the following order:Guangdong soil>Chongqing Soil>Henan soil.The desorption capacity is opposite to the adsorption capacity.