A Study On Environmental Behaviors Of Quinotrione

Quinotrione is a novel systemic selective herbicide of p-hydroxyphenylpyruvate dioxidase（HPPD）inhibitor jointly developed by Central China Normal University and Shandong Xianda Agrochemical Co.,Ltd.,which has the advantages of high efficiency,low toxicity and safety for later crops,but long-term application may cause environmental pollution and threaten human health.In order to explore the degradation law of quinotrione in the environment and evaluate its environmental safety,this paper uses indoor simulation test method to establish a residue analysis method of quinotrione in water and soil,and studies the hydrolysis,photolysis,soil degradation and migration of quinotrione,and the main results are as follows:1.The residue detection method of quinotrione in water was established by high performance liquid chromatography（HPLC）,and the recovery rate of quinotrione in water was88.4%～104.1%,and the relative standard deviation was 1.5%～6.1%,which met the requirements of quantitative analysis.The effects of p H,temperature,natural water and surfactants on quinotrione hydrolysis were studied under indoor simulation conditions.The results showed that quinotrione was prone to hydrolysis under acidic conditions,and the hydrolysis rate in buffer solution was p H 4>p H 9>p H 7.At the same time,the hydrolysis of quinotrione is affected by temperature,and the increase in temperature promotes the hydrolysis of quinotrione,the temperature increases by 10～15°C,and the hydrolysis rate increases by 2.6～2.9 times.Quinotrione is a refractory pesticide in natural water,and the hydrolysis rate is rainwater>lake water>ultrapure water>groundwater.The cationic surfactant（CTAB）with a mass concentration of 100 mg/L promoted the hydrolysis of quinotrione,while the anionic surfactant sodium dodecyl benzene sulfonate（SDBS）had no obvious effect.2.The effects of light source,initial concentration,p H,natural water,humic acid,riboflavin,Fe³⁺and NO₃^–on the photolysis of quinotrione were studied.The results showed that quinotrione had almost no photolysis within 7 days under the condition of 500 W xenon lamp,and was easily photolyzed under 500 W mercury lamp irradiation,and the photolysis half-life was 28.2 min.The photolysis rate of quinotrione decreases with the increase of the initial concentration.Quinotrione is prone to photolysis under acidic conditions,and the photolysis rate is p H 4>p H 9>p H 7.The photolysis rate of quinotrione in natural water is rainwater>ultrapure water>groundwater>lake water,and the photolysis rate of quinotrione in rainwater is the fastest compared with the ultrapure water control.Low concentrations of humic acid（1mg/L）promote the photolysis of quinotrione and high concentrations（100 mg/L）inhibit its photolysis.Riboflavin,Fe³⁺and NO₃^–all promoted the photolysis of quinotrione,and the photolysis rate increased with the increase of concentration.3.A method for the residual analysis of quinotrione in soil was established by high performance liquid chromatography tandem mass spectrometry（HPLC-MS/MS）,and the recovery rate of quinotrione in soil was between 89.8%～95.4%,and the relative standard deviation was 1.9%～5.7%.Quinotrione was an easily degradable pesticide in different types of soil,and the degradation rates were brown soil>aquic soil>paddy soil>black soil,with half-lives of 14.7,21.0,26.6 and 27.9 d,respectively.The degradation rate of quinotrione in sterilized soil slowed down significantly,indicating that soil microbial degradation was one of the degradation pathways of quinotrione in soil.Soil water content between 40%～80%saturated water content is more conducive to the degradation of quinotrione,and the degradation rate is slowed down under the condition of stagnant water,which proves that aerobic microorganisms in soil are the main factors affecting the degradation of quinotrione.The transfer ability of quinotrione in soil is brown soil>black soil>aquic soil=paddy soil,according to the pesticide movement grade,quinotrione is mobile in brown soil,medium mobile in black soil,and inaccessible pesticide in aquic soil and paddy soil.