【作者】 刘瑜；

【导师】 骆耀平； 张友炯；

【作者基本信息】 浙江大学 ， 园艺（专业学位）， 2016， 硕士

【摘要】 联苯菊酯具有杀虫谱广、低毒、低残留的特点,是茶园中使用率最高的农药之一。因其广泛使用,在茶叶中有较高的检出率。为了提高茶叶的安全性,降低茶叶中的联苯菊酯残留量。本研究从联苯菊酯的检测方法、生产中施药浓度、施液量、施药方向、降雨、采摘标准、烘干条件等因素着手,探讨了生产各环节中不同作业对联苯菊酯残留量带来的影响,为生产实践措施的选择提供参考意见。1.研究针对国标法检测茶叶中联苯菊酯试剂用量较大、过程较繁琐等不足,选用张海伟的固相萃取-气相色谱法进行联苯菊酯的测定,在此基础上比较了不同吸附剂处理对萃取效果的影响。结果表明：层析柱中无水硫酸钠添加与否、弗罗里硅土活化与否,对测定结果无影响。萃取时,层析柱中添加0.1g活性炭,可使图谱基线更平稳。因此,使用固相萃取-气相色谱法进行茶叶中联苯菊酯的检测,不添加无水硫酸钠、弗罗里硅土不活化、添加0.1g活性炭,可使操作更节能、省时。该条件下,茶叶中联苯菊酯添加浓度为0.01 mg.kg～5 mg/kg时,其回收率在84.26±8.24%～108.23±3.05%(n=10),RSD≤8.24%,检出限为0.0017mg/L,符合农残检测要求。2.研究探讨了推荐浓度、加倍浓度,以及常量施药、四倍常量施药对联苯菊酯残留量的影响。结果表明,不同施药浓度对联苯菊酯残留量会带来显著影响。按常量(1320L/公顷)施药时,加倍浓度施药的初始残留量是推荐浓度的2.5倍,7天后,加倍浓度的残留量是推荐浓度的1.47-2.85倍。按常量施药,推荐浓度施药后7天后采摘,茶叶达到安全标准；双倍浓度施药,在7天后采摘农残超标。不同施液量对联苯菊酯残留会带来显著影响。在推荐浓度时,四倍常量施药的初始残留量是常量施药的1.11倍；双倍浓度时,四倍常量施药的初始残留量是常量施药的1.54倍。施药浓度对联苯菊酯残留量的影响大于施液量的影响。3.从叶片上表面和叶背面两个不同施药方向对茶叶喷、涂联苯菊酯。结果表明,使用手动喷雾器,在叶背面喷药时,大量药液被枝干阻挡。背面施药的初始残留量仅为正面施药的13.78%。涂药试验中,背面涂药药液附着量则是正面涂药的121.42%。说明在药液能均匀到达叶片正反面的情况下,叶背面的附着能力更强。涂药7天后,叶片正、背面农药降解率分别为58.74%、59.68%,均降解至农残限量以内。4.不同采摘标准显著影响茶叶中的联苯菊酯残留量。施药后7天,按单芽、一芽一叶、一芽二叶、一芽三叶不同标准采摘的茶叶中农残含量存在差异。初始残留量越高、采摘间隔期越短,不同叶位的农残差异越显著。推荐浓度施药7天后,按一芽三叶采摘的茶叶中农残含量比按一芽二叶、一芽一叶、单芽标准采摘的茶叶分别高出9.52%、76.92%、447.61%。推荐浓度施药三天后采摘单芽和一芽一叶,符合安全标准,提高采摘标准可降低农残超标风险。不同叶位生长速率不同,生长稀释所起的作用也不同,从而影响到不同采摘标准茶叶间的农残差异。5.施用联苯菊酯后的不同时间内降雨对农残含量会带来不同影响。施药后4h、8h、17h、24h模拟降中雨,雨水对联苯菊酯的淋失率不同,分别为48.02%、21.84%、8.98%、-2.10%,即降雨距离施药时间越短,雨水对其冲刷效果越明显。根据不同地方虫情的控制情况,施药后短时内降雨,需考虑补施。施药后24h,降雨对茶叶上联苯菊酯残留量无显著影响。药后24h模拟小雨、中雨、大雨,各处理茶叶中农残含量分别为4.71±0.17mg/kg、4.92±0.024mg/kg、4.84±0.37mg/kg,与对照的4.82±0.22 mg/kg无显著差异。据已有对联苯菊酯试验,施药24h后治虫效果达82.93%-100%。因此,若施药24h后降雨,不必补喷农药。6.加工过程中烘干温度和时间对茶叶中联苯菊酯的减少有显著影响。当烘干温度为90℃、110℃、130℃,烘干时间在Omin～60min时,联苯菊酯残留量随温度升高和时间延长而减少。在烘干前10min农药减少最快,三种温度条件下分别下降10.52%-15.44%,之后农残减少速率逐渐下降。相同烘干时间,烘干时间大于10min时,130℃温度烘干,对联苯菊酯的降解作用显著高于90-C和110℃处理。在保持茶叶有较好品质的前提下,减少茶叶中农残,可考虑在烘干的前10min采用90℃,之后提高到130℃。更多还原

【Abstract】 Bifenthrin is a broad spectrum insecticide, which with low toxicity and residues. It is widely used in Tea Garden. Because of this, bifenthrin have a high detection rate in tea. To reduce the residues of bifenthrin in tea, this study do search for how the production affect the residues. The factors including the determination method, pesticide concentration, applied amount of liquid, spraying direction, rainfall, picking standard and drying conditions.1. The study determinated the bifenthrin by solid phase extraction gas chromatography (SPE-GC). Comparing the chromatograms of the bifenthrin, which were divided by different adsorbents. The results showed that, if anhydrous sodium sulfate is added or not, or Florisil be activated or not, have no effect on the measurement results. When the column was added with 0.1g activated carbon, the baseline of the chromatograms was more stable. Therefore, extract the befenthrin in tea with 1g Florisil(not activated),and 0.1g of activated carbon, without anhydrous sodium sulfate, can operate more energy-efficient and time-saving. Under this condition the average recovery was in the range of 84.26 ± 8.24%～108.23± 3.05%(n=10), RSD≤8.24%, the detection limit was 0.001mg/L. The method can be use in befenthrin determination.2. The effects of pesticide concentration and spray volume on befenthrin residues were studied in this experiment. The results showed that different concentrations of pesticide had a significant impact on the residues of bifenthrin. Sprayed by constant volume, the initial residues of double-recommended concentration were 2.5times as recommended concentration’s.7 days after, the befenthrin residues of the tea sprayed by recommended concentration were lower than the max residues limit (MRL,5mg/kg); the tea sprayed by double-recommended concentration had the risk of excessing the MRL. Spray volume had a significant influence on the residues of bifenthrin. Sprayed by recommended concentration, the initial residues of 4 times-constant volume were 1.11 times as constant volume spraying. Sprayed by double-recommended concentration, the initial residues of 4 times-constant volume were 1.54 times as constant volume. Pesticide concentrations affected the bifenthrin residues greater than spray volume.3. Detected the residues of bifenthrin in tea after spraying or painting the bifenthrin on leaf abaxial and adaxial surfaces. When using manual sprayers spray toward the leaf abaxial surfaces., the pesticide could be blocked by the branches; just a few pesticide could arrive at the leaf. The Initial residues were 13.78% of the bifenthrin in tea which was sprayed on the adaxial surface. When daubing bifenthrin on leaf abaxial and adaxial surface,the Initial residues of the former were 121.42% of the latter. This meant if the pesticide liquid can be uniformly arrive at the leaf abaxial and adaxial surfaces, the former one had the stronger adhesion.7 days after the pesticide degradation of the bifenthrin painted the on leaf abaxial and adaxial surfaces were 59.68% and 58.74%, both of the residues were lower than the MRL.4. Different tea plucking standards significantly affected the amount of bifenthrin residues.7 days after bifenthrin application, single bud, a bud with one leaf, a bud and two leaves and a bud three leaves have significant difference in pesticide content.7 days after sprayed by recommended concentration, the bifenthrin residues of one bud three leaves were 9.53%,76.92%,447.61% higher than the residues in one bud two leaves, one bud one leaf, single bud.3 days after recommended concentrations spraying, picking single bud and one bud with one leaf could compliance with the safety standards. Improved picking criteria could reduce the risk of excessive pesticide residues standard. Leaves in different positions had different growth rates, and had different growth dilute, thus affected the bifenthrin residues between the tea picking by differences tea plucking standards.5. The interval between rainfall and bifenthrin application affected the residues significantly. Simulated moderate rain when 4h,8h,17h,24h after pesticide spraying, the degradation rates were 48.02%,21.84%,8.98%,-2.10%,the shorter the interval, the higher bifenthrin degradation rate. When it was raining short time after bifenthrin application, whether the pesticide should be spraying again or not, need according to the pest control efficiency.24h after bifenthrin application, rainfall had no significant effect on the residual amount of the bifenthr in tea.24h after the application, light rain, moderate rain, heavy rain, had no influence on the bifenthrin residues in tea, the residues were 4.71±0.17mg/kg,4.92±0.024mg/kg,4.84±0.37mg/kg, all had no significant difference with the CK (4.82±0.22 mg/kg). According to the existing reports,24h after bifenthrin application, pest control efficiency was ranged from 82.93% to 100%. Therefore, if the rain occurs 24h after bifenthrin application, there is no need to spray again.6 The drying temperature and duration had a significant impact on tea bifenthrin reducing. When the drying temperature at 90℃,110℃,130℃, drying time during Omin～60min, the higher the temperature and the longer the duration, the less the bifenthrin residues. The former 10min had the biggest degradation, ranged from 10.52% to 15.44%, then as the duration be longer the duration, the degradation was lower. Under the same drying duration(longer than 10min),the degradation of the 130℃’s was significantly higher than 90℃’s and 110℃’s. in order to keep the quality of the tea while reducing the bifenthrin residues, the drying temperature of the former 10min can be 90℃, then increased to 130℃.更多还原