| Powdery mildew is a common disease of pea during its growing period, and it led to the mass deduction of production can reached up to 50%. The new fungicide metrafenone which was produced by the Germany Basf company, it was employed to prevent pea from infected by powdery mildew in many countries and the control efficiency can be satisfied. But until now, few reports about the application risk of metrafenone can be found. To evaluate the safty and environmental behavior of new metrafenone, this paper study on the residue of metrafenone on pea, including the degeradation dynamics, final residue, photolysis and its environmental behavior, the main results are as follows:1. The analytical method of metrafenone residue in pea and soil was described, the samples was extracted by acetonitrile, GCB, C18 and PSA as purifying agent, external standard method for quantitative standard, by UPLC-MS/MS. Linear, accuracy of the method were analyzed. The results showed that, the method with good linearity, and R2 was greater than 0.999. The recovery in the 4 matrices including pea grain, Pea, pea shoots and soil were between 73.5%-105%, and the relative standard deviation were from 1.9% to 13.5%, which can be satisfied the requirements of the analysis of pesticide residues. LOQ were between 0.02-0.07mg/kg which was much lower than 0.05mg/kg the current MRLs employed by European Union.2. Study on dissipation dynamics of metrafenone in field, and the results showed that the dissipation dynamics of metrafenone in Peas and soil can be well described by the first kinetic equation Ct = C0e-kt, and the average deposit in Pea and soil were 0.39-0.53mg/kg and 0.64-1.12mg/kg, with the half-life were 3.40-4.68 d and 6.00-14.44 d. According to the Environmental safty evaluation standard of pesticide, metrafenone belong to the pesticide that easy to degrade. And the result of final residue showed that, the final residual deposit on pea were lower than 0.01mg/kg after five days of the last time that metrafenone was sprayed. At present, there have no MRLs of metrafenone on pea in China while it is 0.05mg/kg employed by European Union. So, it is reasonable to suggest that the MRLs of metrafenone are set at 0.05mg/kg on pea in our country.Fair use advice: the dose of 500g/L metrafenone suspension were spayed to prevent pea from infected by powdery mildew, with the highest dose are 24 m L/mu(the dose of active content are 180g/ha), at most 3 times are permitted, and the application interval are 7 to 10 days, and the recommended preharvest safty interval are 5 days.3. Study on the photolysis of metrafenone in 6 organic solvents and water, the results suggested that the order degradation rate of metrafenone while it was exposed to the light from artificial xenon lamp(3700-4000lux), are water < methanol < acetonitrile < hexane < ethyl acetate < dichloromethane <acetone, with half-life of photolysis are 173.3h、63.0h、63.0h、34.7h、28.9h、23.1h and 11.2h, respectively. Metrafenone belong to the pesticide that easy to photolyze.4. In this study, the typical methods of soil thin-layer and column leaching were adopted to investigate the leaching behavior of new fungicide metrafenone in three typical soils. The result showed that the Rf of fluvo-aquic soil of Hebei, red soil of Hunan and black soil of Harbin are 0.17, 0.26 and 0.15, respectively. While 99%, 80% and 99% of the original dose of metrafenone are in the first soil column(0~30 cm). According to the Chinese guidelines on environmental safety assessment for chemical pesticides, the leaching character of metrafenone is classified as Ⅳ grade, and it will not to pollute groundwater in leaching. |
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