13种农药在乌龙茶中残留变化的研究

Variation Characteristics of 13 Pesticides' Residue in Oolong Tea

为了探索乌龙茶中农药的残留变化和影响特征,笔者采取田间农药喷施的方式,获取了3个浓度梯度7类共13种农药呈阳性的茶青,再经传统乌龙茶加工工艺制备成乌龙茶。通过测定茶青和成茶的农药残留量,研究喷施浓度、农药背景浓度和属性对乌龙茶中农药残留量变化的影响。结果显示,随着农药喷施浓度的提高,茶青中残留的农药量随着增加,但残留量增加比例有所下降。乌龙茶成茶的农药残留量比茶青低,仅为茶青的76%,3种浓度农药残留茶青的损失率略有不同,不同种类农药残留量损失程度差异较大。其中,恶二嗪类农药、烟碱类农药损失较大,达47.95%、39.11%;噻二嗪酮类农药、拟除虫菊酯类农药损失较小,为6.55%、11.05%;茚虫威损失率最高,噻嗪酮的损失率最低。研究表明农药喷施浓度、农药背景浓度和农药属性均是其农药残留量变化的影响因素。

The paper aims to explore the variation characteristics and effect of pesticide residue in Oolong tea.Pesticide residue in Oolong tea of 3 concentration gradients and 13 pesticides including organophosphorouspesticide, synthetic pyrethroid pesticide, nicotinic pesticide, acaricide and etc. were studied by sprayingpesticide in a field trial and tea preparation with traditional manufacture process. Then, the authors determinedpesticide residue in tea leaves and Oolong tea, and analyzed the effects of spraying concentration, backgroundconcentration, and pesticide property on residue variation. The results showed that： the amount of pesticides intea leaves increased with the increase of spraying concentration; while their increasing degree decreased; theamount of pesticide residue in Oolong tea was 76% of that in tea leaves; the pesticide loss ratio was slightlydifferent among the 3 concentrations in tea leaves, but different pesticides had different loss ratio; the loss ofoxadiazine pesticide and nicotine pesticide was relatively high（47.95% and 39.11%, respectively）; however,that of thiadiazine ketone pesticide and synthetic pyrethroid pesticide was low（6.55% and 11.05%,respectively）; the loss of buprofezin was the lowest among these pesticides, while that of indoxacarb was thehighest. It was conclude that spraying concentration, background concentration, and pesticide property allcontributed to the variation of pesticide residue in Oolong tea.