微塑料因其尺寸小，对生物体产生危害，并通过食物链进行迁移或生物放大，对生态系统构成威胁，因此其毒理学效应越来越受到重视。为探讨微塑料和重金属复合污染对土壤生物的毒性效应，本研究选取聚苯乙烯（PS，5 μm）和重金属镉（Cd）作为受试毒物，以赤子爱胜蚓（Eisenia Fetida）作为受试生物，采用滤纸接触法（48h）和人工土壤法（14 d），开展Cd-PS不同浓度复合暴露对赤子爱胜蚓的毒性效应研究，从急性毒性、氧化损伤、物质代谢、遗传毒性等角度进行评价。主要研究结果如下： 1）急性毒性试验结果表明，PS的存在一定程度上降低了Cd对蚯蚓的毒性效应；2）通过对超氧化物歧化酶（superoxide dismutase, SOD）、过氧化氢酶（catalase, CAT）活性和脂质过氧化产物丙二醛（malondialdehyde, MDA）含量的测定，可知微塑料和重金属的复合暴露使蚯蚓产生氧化损伤；3）纤维素酶（cellulase, CL）和碱性磷酸酶（alkaline phosphatase, AKP）活性受到抑制，说明复合污染胁迫对蚯蚓物质代谢能力产生影响；4）采用蚯蚓体腔细胞彗星试验，检测彗尾长度（Tail length, TL）、彗尾DNA含量（Tail DNA%）和Olive尾矩（Olive tail moment, OTM）三项指标，结果显示Cd-PS复合暴露造成蚯蚓体腔细胞DNA断裂的基因损伤。本论文为微塑料与重金属复合污染研究提供了基础数据，微塑料和重金属复杂的复合毒性机理有待进一步研究。

Microplastics have attracted more and more attention to its toxicological effects, because their small size renders them cause harm to organisms, and migration or biomagnification through the food chain, finally endanger the ecosystem. To investigate the toxic effects of the combined pollution of microplastics and heavy metals on soil organisms, polystyrene (PS, 5 μm) and heavy metal cadmium (Cd) were selected as the tested poisons, and earthworm (Eisenia Fetida) as the test organism. Filter paper test (48h) and artificial soil test (14d) were used to investigate the mixture toxicity effects of exposure to different doses of Cd-PS at different concentrations on E.fetida, from the aspects of acute toxicity, oxidative damage, substance metabolism and genotoxicity. The main results are as follows: 1) The results of acute toxicity test showed that the presence of PS reduced the toxicity of Cd to earthworms to a certain extent. 2) Through the determination of superoxide dismutase (SOD), catalase (CAT) activity and malondialdehyde (MDA) content, it can be seen that the composite exposure of microplastics and heavy metals caused oxidative damage to earthworms; 3) The activities of cellulase (CL) and alkaline phosphatase (AKP) were inhibited, suggesting that the effects of compound pollution stress on the metabolism of earthworms; 4) Tail length (TL), Tail DNA% and Olive tail moment (OTM) were detected in the comet assay to observe the DNA damage level, results showed that Cd-PS exposure resulted in DNA damage to DNA single-strand breaks in the earthworm coelomocyte. The thesis provides basic data for the study of the composite effect of microplastics and heavy metals. The complex mixture toxicity mechanism of microplastics and heavy metals needs further study.