Study On Environmental Behaviors Of Cyflufenamid

Cyflufenamid is a novel fungicide currently in development by Nippon Soda Co., Ltd.(Nisso). Cyflufenamid shows excellent control activity against powdery mildew in various plants and brown rot in stone fruits. This study established the residue analysis method of cyflufenamid in both water and soil, investigating systematically this fungicide of degradation in light, water chemistry, soil, and soil absorption-desorption, as well as soil migration. By monitoring all these characters, it can be contribute to systematically understand the residue dynamics and conversion process of cyflufenamid for evaluating its ultimate destination and potential environment damage. Therefor, all results could be used to guide the use of this fungicide, as well as provide the evidence to eliminate environment contamination. Research details are below:(1) A rapid and low-cost method for determining cyflufenamid in water and soil by Gas Chromatography coupled to mass spectrometry(GC-MS) in selected ion monitoring(SIM) mode was established. Results show that the established method achieved a good linear relationship over the range of 0.01 mg/kg to 5.0 mg/kg for cyflufenamid(R2 =0.9999). The average recoveries were 90.2~101.2% ? 89.5~94.7% ? 85.6~94.7% and85.6~91.4% in water, paddy soil, forest soil and city soil for cyflufenamid at the spiking Levels of 0.01, 0.1 and 1.0 mg/kg. The relative standard deviations(RSDs) were3.8~5.4%?3.9~6.6%?2.1~7.5% and 3.4~5.6% in water, paddy soil, forest soil and city soil for cyflufenamid, respectively. The limits of detection(LOD) of cyflufenamid in water and soil were 0.6 and 1.2 ?g/kg, respectively. This method is satisfying the requirements of pesticide residue analysis and determination.(2) The kinetics of hydrolysis of cyflufenamid was studied in different p H buffer and temperature under the laboratory condition and in natural water under simulating field environment. The hydrolysis rate of cyflufenamid fits first-order kinetic equation. The half-life was 231.3 d, 99.1 d and 30.2 d in the solutions of p H 5, 7 and 9 at 25 °C,respectively. The hydrolytic rate of cyflufenamid increased with the increasing temperature,the average temperature coefficient of hydrolysis for cyflufenamid was 2.6. The half-life of cyflufenamid was 16.9 d in natural water under simulating field environment, whose speed is obviously faster than that of lab conditions. Under simulating field environment, light intensity and microorganisms may have significant effect on the degradation of cyflufenamid in water.(3) The photolysis trend of cyflufenamid in different kinds of solvents under ultraviolet lamp and sunlight illuminating was investigated. The affecting factors were studied under different conditions including Light sources, organic solvents and the initial concentrations. The photolysis of cyflufenamid fits first-order kinetic equation. The photolytic rate of cyflufenamid in water under different light sources was significant different to each other. The half-life under ultraviolet lamp and sun light were 23.9 d and46.3 d, respectively. The photolytic rate was influenced by initial concentration of cyflufenamid. The photolytic rate showed negative correclation with the initial concentration of cyflufenamid. The photolytic rate of cyflufenamid in acetonitrile was faster than that in n-hexane and acetone.(4) The half-lives of cyflufenamid in paddy soil, forest soil and city soil were 34.7 d,23.0 d and 57.8 d, respectively, while in those three sterilized soils, the half-lives were 49.6d, 43.4 d and 63.1 d, respectively. It indicated that soil microorganisms had effect on the degradation of cyflufenamid in soil. The main influence factors of degradation rate were organic matter content.(5) The adsorption and desorption in three kinds of soils of cyflufenamid were studied with batch equilibrium technique. Adsorption isotherms of cyflufenamid on the soils could be described well by Freundlich equation, its correlation coefficient(R2) is 0.9451~0.9987.The adsorption constant(Kd) of cyflufenamid in paddy soil, forest soil and city soil were2.87, 1.18 and 0.91, respectively, which indicated that cyflufenamid was difficult to adsorb by those three soils. The adsorption and desorption in three kinds of soils of cyflufenamid are reversible.(6) The mobility of cyflufenamid in three kinds of soils was studied with soil thin layer chromatography(STLC). Relative flow(Rf) of cyflufenamid in paddy soil, forest soil and city soil were 0.38, 0.56 and 0.61, respectively. The mobility of cyflufenamid in threedifferent soils above mentioned all belonged to middling mobile pesticide. Mobility of cyflufenamid in three different soils is ranking from fast to low as city soil, forest soil, and paddy soil.