土壤中低剂量吡虫啉-铬(Ⅵ)复合污染的毒性效应及其致毒机制研究

Accumulation of pesticides and heavy metals in the soil causes significant adverse effects on soil organisms. A clear understanding of their toxicological effects on soil animals is important for the correct evaluation of the compound effects of pollution and effective protection of the soil fauna. In this work, earthworm, the terrestrial invertebrate was chosen as model organism. imidacloprid, the one of widely used pesticide, and chromium (Ⅵ), the common heavy metal in soil, were chosen as the research object. Base on the effect on the earthworm’s acute and subacute toxic index (growth, propagation, elusive behavior, etc.) with individual or combine existence of imidacloprid and chromium, the toxic effect of combination of imidacloprid and chromium (Ⅵ) with low dose and high touch time was studied in the angle of tissue, cell, and subcellular level. Furthermore, their toxic mechanism was explored in the molecular level. On the point of view of chemistry and biology, the residue-response mechanism of imidacloprid and chromium (Ⅵ) were clarified. The object of this work is to explore the toxic mechanism of the combined pollutant with low dose on the earthworm in molecular level, and screen the effective biological mark for the early diagnosis of low dose of combined pollution of imidacloprid and chromium (Ⅵ). This study will provide early management,theoretical basis and scientific method for low-dose effects of combined pollution between pesticide and heavy metal in soil.

土壤中不断积累的农药和重金属对土壤动物造成了严重不利影响，明确他们对土壤动物的毒理效应和致毒机理，对于正确评价复合污染效应，有效保护土壤动物非常重要。本项目拟以陆生无脊椎动物蚯蚓为模式生物，选用广泛使用的农药之一吡虫啉和土壤中普遍存在的重金属之一铬(Ⅵ)为主要研究对象，根据两者单独存在与共存条件下对蚯蚓急性和亚急性毒性指标（生长、繁殖及回避行为等）影响的毒性信息，重点从组织、细胞和亚细胞水平上研究低剂量长期暴露下吡虫啉-铬复合污染对蚯蚓的毒性效应，进而在分子水平上探讨复合污染的致毒机理。从化学和生物两方面结合的角度，揭示吡虫啉-铬（Ⅵ）复合污染的剂量-效应关系。本研究旨在阐明低剂量复合污染物对蚯蚓的分子毒性机理，筛选出能够灵敏度高的，可以用于早期诊断低浓度吡虫啉-铬（Ⅵ）复合污染的有效生物标志物，为土壤中低剂量农药-重金属复合污染的早期预警及其修复治理提供可靠的理论依据和科学方法。

土壤中不断积累的农药和重金属对生态系统造成了严重威胁，且经常构成复合污染，明确他们共存时的毒性效应及其致毒机理，对于准确评价复合污染对土壤生物毒副作用和有效保护生物多样性非常重要。本项目以土壤动物赤子爱胜蚯蚓（Eisenia fetida）为受试生物，选用土壤中广泛存在的新烟碱类农药吡虫啉和重金属铬（Ⅵ）为研究对象，根据它们单一与复合暴露时对蚯蚓急性毒性影响的信息资料，重点从亚细胞和分子水平上测定吡虫啉和铬（Ⅵ）共存下对蚯蚓的毒性效应，在分子水平上探讨复合污染的毒作用机理。具体评价了吡虫啉和铬（Ⅵ）单一及复合污染对蚯蚓组织病理、溶酶体膜稳定性、DNA 损伤和基因差异表达的影响，明确了各级水平毒性指标的响应规律和剂量-复合效应关系，阐明了联合毒性机制，且建立了复合污染分子诊断技术。该研究成果可以为早期诊断土壤中农药-重金属复合污染物提供有效敏感生物标志物，这不仅为土壤污染的早期预警提供灵敏指标，同时为研究土壤动物的生态毒理学和评价复合污染的生态风险提供科学依据，也为建立土壤复合污染评价技术体系及其修复基准提供理论基础，最终为改善生态环境提供技术支撑。