手性农药对映体在土壤及土壤生物体内的立体选择性行为研究
文献类型：学位论文
| 作者 | 秦芳 |
| 学位类别 | 博士后 |
| 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 | 手性农药 对映异构体 立体选择性降解 立体选择性富集 立体选择 性毒性 chiral pesticide enantiomer stereoselective degradation stereoselective bioaccumulation enantioselective toxicity. |
| 其他题名 | Studies on Enantioselective Behavior of Chiral Pesticides in Soils and Soil Invertebrate |
| 学位专业 | 环境科学与工程 |
| 中文摘要 | 手性农药进入环境后，其不同对映体在环境中的持久性及其生物活性、毒性、吸收、转移及代谢等方面均存在着差异。本报告利用高效液相色谱串联质谱(HPLC-MS/MS)手性固定相方法研究了手性农药呋霜灵和苯霜灵在不同质地农田土壤中、氟虫腈和呋霜灵在土壤生物蚯蚓体内以及氟虫腈在植物中的立体选择性环境行为。 通过向六种不同类型的农田土壤中分别添加外消旋呋霜灵和苯霜灵及其单一对映体进行培养，研究呋霜灵和苯霜灵在这些土壤中的降解动态及选择性降解情况，分析影响手性农药立体选择性降解的因素，考察降解与吸附和淋溶相关性。结果表明呋霜灵和苯霜灵在这些土壤中的降解趋势符合一级动力学方程(R2 >0.96)，S-呋霜灵、R-呋霜灵、S-苯霜灵和R-苯霜灵的半衰期分别为19.3-49.5 d、11.4-34.7 d、27.7-57.8 d和20.4-53.3 d。呋霜灵和苯霜灵在部分土壤中的降解是立体选择性的，R-异构体的降解速率均高于S-异构体的降解速率。同时这两种手性农药被土壤吸附的能力越大，降解的就越慢，半衰期就越长，而柱淋溶中出现的立体选择性与农药降解有关。与苯霜灵相比，呋霜灵在这些土壤中的降解速率要快，半衰期要短，立体选择性要明显。这些表明土壤的物理化学性质和微生物以及农药的理化性质等因素影响手性农药在环境中的命运。 利用滤纸片接触法测定了呋霜灵消旋体及两个单一异构体对蚯蚓的选择性急性毒性，利用自然土壤法研究了氟虫腈消旋体和两个单一异构体对蚯蚓生长(鲜重)的影响以及蚯蚓对呋霜灵和氟虫腈的选择性富集和代谢行为。结果表明，S-呋霜灵对蚯蚓的急性毒性要略高于消旋呋霜灵，而消旋呋霜灵的毒性又高于R-呋霜灵；R-氟虫腈对蚯蚓生长的毒性要低于S-氟虫腈和外消旋体；呋霜灵和氟虫腈在各自30天左右的富集实验过程中在蚯蚓体内均有富集，并存在立体选择性，蚯蚓体内对映体的浓度：S-呋霜灵>R-呋霜灵，S-氟虫腈>R-氟虫腈，氟虫腈代谢物氟虫腈砜和硫化氟虫腈在蚯蚓体内也有一定程度的富集；呋霜灵对映体在蚯蚓体内消除较快，半衰期小于1天，而氟虫腈对映体的半衰期在1.3-2.1天。 最后，在大田试验条件下，对氟虫腈对映体及其代谢物在作物玉米中的消解以及最终残留的立体选择性情况进行了研究，结果表明：氟虫腈对映体在土壤和玉米植株中的消解符合一级动力学方程(R2 >0.91)，R-氟虫腈和S-氟虫腈在玉米植株中的半衰期分别为3.7和4.3 d (北京)，5.9和7.8 d (安徽)，有明显的立体选择性，R-氟虫腈的消解速率快于S-氟虫腈；氟虫腈母体化合物及其代谢物在作物收获期的残留量都很少，低于定量限。因此，从作物保护、环境污染以及人体健康的角度来看，氟虫腈作为玉米拌种剂在推荐剂量的使用是很安全的。 |
| 英文摘要 | When chiral pesticides enantiomers enter into the environment and interact with enzymes or other chiral molecules, they usually react differently or selectively. The enantioselectivity of chiral pesticides often results in different rates of microbial transformation and differences in environmental behavior and fate, activity, toxicity, absorption, metabolism, and transfer of the two enantiomers. In this work, the enantioselective degradation of furalaxyl, benalaxyl and fipronil in plant and soils were investigated based on HPLC-MS/MS with chiral stationary phase technology. The enantioselective bioaccumulation, degradation and toxicity effects of furalaxyl and fipronil on soil invertebrate of earthworms were also studied. The dissipation dynamic and enantioselective degradation of furalaxyl and benalaxyl in soils were studied by incubation with racemate and individual enantiomers in six agriculture soils. The degradation process of the two fungicides enantiomers followed the first-order kinetics well (R2 >0.96). The half-life of S-furalaxyl, R-furalaxyl, S-benalaxyl and R-benalaxyl were 19.3-49.5 d, 11.4-34.7 d,27.7-57.8 d and 20.4-53.3 d, respectively. The degradation of furalaxyl and benalaxyl was enantioselective, and R-enantiomer was degraded faster than S-enantiomer on partial soils. Sorption protected pesticides from degradation and the enantioselectivity of chiral pesticides degradation process and made pesticides remain racemic longer than the readily biodegradable fraction. The enantioselectivity during leaching resulted from degradation behavior. Compared to furalaxyl, benalaxyl was degraded more slowly and less enantioselectively. These results should be attributed to the affection of soil physicochemical properties, soil microorganisms and environmental factors. The enantioselective toxicities of individual enantiomers of furalaxyl in earthworm (Eisenia foetida) were studied by filter paper contact test. The subchronic toxicity of fipronil enantiomers and the enantioselective bioaccumulation and degradation of furalaxyl and fipronil were studied after earthworms were exposed to contaminated soil. The acute toxicity of furalaxyl enantiomers was enantioselective, and R-furalaxyl was the least toxic compared with racemate and S-form. The fipronil enantiomers were no acute toxicity but they caused subchronic toxicity to E. foetida growth, with increased toxicity from racemate and S-fipronil compared with R-fipronil. In bioaccumulation experiments, the results indicated that earthworms can bioaccumulate furalaxyl and fipronil, and the bioaccumulations were enantioselective. The concentrations of enantiomers in earthworms were S-furalaxyl > R-furalaxyl，S-fipronil > R-fipronil. The earthworms had accumulated fipronil sulfide and sulfone. The half-lives of fipronil enantiomers were 1.3-2.1 d, however the half-lives of furalaxyl enantiomers were short (t1/2 <1.0 d). The dissipation and residue of fipronil and its metabolites in maize under field conditions were investigated. The degradation process of fipronil enantiomers followed the first-order kinetics well (R2 >0.91). The half-life of R-fipronil and S-fipronil in maize plants was 3.7 and 4.3 (Beijing), 5.9 and 7.8 (Anhui), respectively.The degradation of fipronil enantiomers in maize plants was enantioselective, and R-fipronil was degraded faster than S-fipronil. The residue of fipronil and its metabolites in the harvest were below the limit of quantification and the risk quotient (RQ) value was significantly lower than RQ = 1. Therefore, the risk of fipronil as a seed-coating formulation use in maize at the recommended dosage was negligible to humans. |
| 公开日期 | 2015-06-16 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/13473]  |
| 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 | 秦芳. 手性农药对映体在土壤及土壤生物体内的立体选择性行为研究[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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