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溴氰菊醋在田间条件下在茶树新梢上降解很缓慢,低于二氯苯醚菊酯;它在叶表的渗透力较弱。以每亩0.44—0.73克有效成份用量(合2.5％乳剂6000—10,000倍液)喷施茶树后,鲜叶中原始附着量(以鲜叶干重计)为1.34—3.23ppm。溴氰菊酯在鲜叶和成茶中的半衰期(按原始附着量计算)均为2.8天。气候条件对溴氰菊酯降解的影响较小,但如喷药后1-2天遇雨会加速溴氰菊酯残留量的降解。由于溴氰菊酯的蒸气压特低,因此鲜叶中的残留量通过加工过程的降解率很低,平均仅为29.79%。由于溴氰菊醋在水中溶解度很低,因此,成茶中的残留农药,在泡茶过程中,进入茶汤中的数量,不会超过其中含量的1％。 根据已报道的溴氰菊酯的ADI值,作者建议溴氰菊酯在成茶中的暂定允许残留标准为2ppm,茶树喷施2.5％乳剂 6000—10,000倍液时的安全间隔期为3天,这样通过茶汤进入人体的量不会超过0.02ppm。
Deltamethrin vinegar degraded slowly on the shoots of tea trees under field conditions and was less permethrin; its penetrability was weaker on the leaf surface. After the tea plants were sprayed with 0.44-0.73 g of active ingredient per acre (combined with 6000-10,000 times 2.5% emulsions), the original amount of fresh leaves (based on fresh leaf dry weight) was 1.34-3.23 ppm. The half-life of deltamethrin in fresh leaves and tea (calculated as the original weight) was 2.8 days. Climatic conditions have little effect on the degradation of deltamethrin, however, if rain is found 1-2 days after spraying, the degradation of deltamethrin will be accelerated. Due to the extremely low vapor pressure of deltamethrin, the degradation rate of fresh leaves by the process is very low, averaging only 29.79%. Due to the low solubility of deltamethrin in water, residual pesticides into tea can not exceed 1% of the amount of tea in the brewing process. Based on reported ADI values of deltamethrin, the authors suggest that the tentative allowable residue level for deltamethrin in tea is 2 ppm, and that for tea plants sprayed with 6000-10,000 times 2.5% emulsions is 3 days , So that the amount of tea into the body will not exceed 0.02ppm.