三唑类手性农药在食物链中的蓄积和传递
文献类型：学位论文
| 作者 | 陈锦辉 |
| 学位类别 | 博士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 李建中 |
| 关键词 | 食物链 三唑类农药 手性农药 安全性评价 蓄积 food chain triazoles chiral pesticide safety evaluation accumulation |
| 其他题名 | Accumulation and Transfer of Chiral TriazolePesticides in Food Chain |
| 学位专业 | 环境科学 |
| 中文摘要 | 全球有现有 1600余种的农药，其中 30%以上的农药具有手性。由于农业生产的现代化，农药的使用量也越来越大。农药通过作物的吸收、残留、蓄积和传导，最终会影响到人类。对于手性农药，由于手性中心的存在，使得其手性异构体之间的生物活性、环境行为和环境毒理差异变得不同。但是，在使用上并未对这种差异进行区分，导致部分低活性、持久性和蓄积性的异构体进入了环境和生态，由此引发的安全问题也值得去详细的研究。 本研究通过对手性三唑农药己唑醇、氟环唑、烯唑醇在食物链土壤-蚯蚓-鹌鹑中的行为进行了研究。在此过程中，建立了一种同时测定五种三唑类农药的十个异构体在土壤、蚯蚓、鹌鹑（血液、心脏、肝脏和肾脏）中的方法。该方法通过研磨、超声和离心对样品进行提取，用 GPC进行净化，利用 Chiralcel OD-3R手性色谱柱，在超高效液相色谱-三重四级杆质谱上实现了十个异构体的分离。通过对方法的选择性、专属性、检测限、精密度、回收率、线性和方法的稳定性来进行了方法学的验证表明，这此方法满足试验的需求。 建立了蚯蚓富集土壤中手性农药的方法，并用此方法研究了己唑醇、氟环唑、烯唑醇在蚯蚓中的富集特性。将蚯蚓（Eisenia foetida）暴露于三个不同浓度的三个不同手性三唑类农药中，结果表明，这三种农药的对应异构体在蚯蚓体内的蓄积和消除阶段都存在着立体选择性，他们的蓄积性表现出与 log KOW值成正比的关系。并且，蓄积性与暴露浓度密切相关，随着暴露浓度的增大，达到蓄积平衡状态所需要的时间也越短。从富集因子 BSAF值来看， 己唑醇和烯唑醇的富集因子随着暴露浓度的增加而增大，而氟环唑的富集因子则是随着暴露浓度的增加而下降。但这种选择性与农药的结构有密切的关系。随着与手性碳原子相连的基 团的活性的升高，在蓄积和消除阶段的立体选择性为烯唑醇>氟环唑>己唑醇。 己唑醇、烯唑醇和氟环唑在鹌鹑（Coturnix coturnixs japonica）体内的代谢动力学表明，己唑醇和烯唑醇的代谢过程符合房室模型中的一室模型，而氟环唑的代谢则是一阶动力学模型。代谢半衰期的研究表明，与三种农药的结构有关，其半衰期也趋近于烯唑醇>氟环唑>己唑醇，其选择性代谢的程度也趋近于烯唑醇>氟环唑>己唑醇。R-烯唑醇在鹌鹑肝脏和肾脏有严重的蓄积。从鹌鹑的血液、心脏、肝脏和肾脏中，发现了己唑醇、烯唑醇和氟环唑的代谢物。依据这些代谢物出现的时间顺序和结构，推测了其在鹌鹑体内的代谢路径。 以土壤、蚯蚓、鹌鹑组成典型的农田食物链，研究了三唑类手性农药烯唑醇、己唑醇和氟环唑在这条食物链中蓄积和传递。实验表明，三种手性三唑类农药在食物链中存在传递效应，传递的程度，随 log KOW值的增大，依次为烯唑醇>己唑醇>氟环唑。三种手性三唑类农药食物链中的蓄积具有选择性，选择性的显著性与结构中，与手性碳原子相连的基团的活性有关，依据活性的顺序烯唑醇>氟环唑>己唑醇，其在食物链中立体选择性的顺序为烯唑醇>氟环唑>己唑醇。在食物链中，随营养级的升高，立体选择性差异越来越明显。三种农药的代谢物随食物链营养级的升高，蓄积越来越严重。 |
| 英文摘要 | There are more than 1,600 pesticides using in the world, 30% of them are chiral. Due to the modernization of agriculture, pesticides became an indispensable part of planting. The applied pesticide to farmland is absorbed by crops, transferred by food chain, and ultimately affecte humans. For chiral pesticides, because of the chiral centers, the biological activity, the environmental behavior and toxicity are different between the enantiomers. The chiral pesticide is usually used as racemic, which may take the low activity, persistence and accumulation one of the enantiomers into the environment and ecosystem. This will lead to environmental pollution and biological extinction in the long run. Thus, the study of chiral pesticides in environment and ecosystem is very important. The accumulation and transfer of chiral triazole pesticides in the food chain soil-earthworms-quail was studied. First, a method for simultaneous detection of ten enantiomers of five chiral triazole pesticides (hexaconazole,epoxiconazole, diniconazole, myclobutanil, tetraconazole) was conducted on liquid chromatography tandem mass spectrometry. The soil sample, earthworm sample and quail tissue sample wereextracted by acetonitrile byhigh speed homogenizing, ultrasonic bath and centrifuging.Then they were clearnuped by GPC. At last the ten enantiomers were separated on a Chiralcel OD-3R chiral column, and been determined on an Ultra-Performance Liquid Chromatography tandem mass spectrometry. The LOD, LOQ, precision, recovery and linearity of methods were studied. And the results showed that this method was satisfied to the study. Earthworms(Eisenia foetida)were exposed to three concentrations of hexaconazole, diniconazole and epoxiconazole enantiomer (1 mg/kg, 10 mg/kg and 25 mg/kg) in artificial soil (dry weight). The accumulation and elimination were stereo selectivity. And the changes of the EF (enantiomer fraction) were closed to the activity of the group bonded to chiral center, which made the stereo selectivitive orderdiniconazole > epoxiconazole > hexaconazole.The accumulation results of the studies were closed to the log KOW value of the pesticide, which mad the accumulation order diniconazole > hexaconazole > epoxiconazole.The accumulation in earthworms was related to the exposure concentration. The steady state of the accumulation came fast as the increasing of exposure concentrations. The bioaccumulation factors of hexaconazole and diniconazole increasedas the increasing of exposure concentrations, and the bioaccumulation factors of epoxiconazole decreased the increasing of exposure concentrations. The pharmacokinetics of diniconazole, hexaconazole and epoxiconazole enantiomers in quail (Coturnix coturnixs japonica) was investigated. The results showed, pharmacokinetic of diniconazole and hexaconazole fitted one-compartment model, while epoxiconazole fitted first-order kinetic model. The studies showed that the the half-life of diniconazole, hexaconazole and epoxiconazole enantiomers were closely related to the the activity of the group bonded to chiral center, which made the order of diniconazole > epoxiconazole > hexaconazole. The R-diniconazole showed high risk of accumulation in quail liver and kidney.The metabolites metabolic pathways of diniconazole, hexaconazole and epoxiconazolewere studied in this paper. The accumulation and transfer of triazole chiral pesticides in the food chain soil-earthworm-quail was studied. It was found that stereoselective accumulationrisk increased as the extension of the food chain. The accumulation order was same to the log KOW order of diniconazole > hexaconazole >epoxiconazole.The stereo selectivitivity in the food chain was closed to the activity of the group bonded to chiral center, which showed an order of diniconazole > epoxiconazole > hexaconazole.The stereo selectivitivityincreased as the increasing of trophic level. The metabolites of the three chiral pesticides accumulated strongly in the food chain, and also increased as the increasing of trophic level. |
| 公开日期 | 2015-07-08 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15715]  |
| 专题 | 生态环境研究中心_中国科学院环境生物技术重点实验室 |
| 推荐引用方式 GB/T 7714 | 陈锦辉. 三唑类手性农药在食物链中的蓄积和传递[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：生态环境研究中心
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