水环境中金属纳米颗粒与微藻的交互作用机理研究

The fate and ecotoxicity of metal nanoparticles (MNPs) has become one of the most focused ecological security problems. The toxicity effects of MNPs on organisms have been widely confirmed. However, Previous research results based mainly on the acute toxicity assays can not reveal the physiological defense mechanism of organisms under long-term stress of MNPs, and the interaction mechanisms between organisms and MNPs are also still unclear . Three typical MNPs (Ag, CuO and ZnO nanoparticles) and two model microalgae (C. vulgaris and C. reinhardtii) are selected as the research objects in this project. The physiological defense mechanisms of microalgae will be revealed by investigating the long-term effects of MNPs on the physiological-biochemical characteristics, the related genetic transcription, and the proteomics expression of microalgae. The effects of microalgae on the speciation distribution, the oxidation-reduction processes, and other related characteritics of MNPs will be investigated to illuminate the biochemically driven processes caused by microalgae in aquatic environment. The adsorption and assimilation of MNPs by microalgae, as well as the impacts of microalgae on the bioavailibility of MNPs, will also be investigated to explore the mechanism for the biological remediation of MNPs by microalgae. The results of this study will provide new theoretical basis for further understanding of the fate and ecotoxicity of metal nanoparticles, and will supply some scientific bases for bioremediation of nano-metal pollution by simple organisms in environment.

金属纳米颗粒（Metal Nanoparticles，MNPs）的环境归趋及生物效应已引起广泛关注，MNPs对生物的毒性效应已得到证实，然而基于急性毒性实验基础上的结果难以揭示MNPs长期胁迫下生物的生理防御机制，而生物与MNPs的交互作用机制也尚不明确。本项目以3种MNPs（Ag-NPs、CuO-NPs和ZnO-NPs）和2类微藻（小球藻和莱茵衣藻）为研究对象，研究MNPs长期胁迫下微藻的生理生化特性、基因转录和蛋白质组等的响应，揭示MNPs对微藻的毒性机理及微藻的防御机制；研究微藻对MNPs在水环境中的形态分布、氧化还原等的影响，阐明微藻对MNPs在水环境中归趋的生物化学驱动机制；研究微藻对MNPs的吸附、吸收及生物有效性的影响，探讨微藻对MNPs进行生态修复的机理。研究结果将为理解MNPs的环境归趋及生态效应提供新的理论基础，在实践上也可为水环境中MNPs污染的生物修复提供科学依据。

金属纳米颗粒（MNPs）的生态毒性和环境归趋及其生物效应已成为目前国内外的研究热点之一，本研究探讨了微藻与纳米金属（MNPs）的交互作用机制，研究表明：.MNPs毒性效应：MNPs抑制了莱茵衣藻的生长和光合作用，且MNPs破坏了亚细胞结构，诱导了活性氧自由基（ROS）的产生，使细胞膜通透性增强，细胞大小变小，MNPs的毒性是纳米颗粒本身和离子释放共同作用结果，尺寸越小毒性越强。.藻类对MNPs防御过程：MNPs刺激了藻胞外多糖和蛋白分泌，对MNPs起到隔离作用；胞内超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）的活性和谷胱甘肽（GSH）的含量增加，从而清除胞内过多的ROS，减轻氧化损伤；同时植物螯合素（PCs）与MNPs发生螯合作用，转运到液泡隔离，起到胞内防御的作用，且藻细胞内发生了CuO还原为Cu2O的生物内化转化过程。.藻类对MNPs分子响应：纳米氧化铜（CuO-NPs）胁迫后，藻细胞参与卟啉与叶绿素代谢、类胡萝卜素生物合成、碳固定、光合作用和光合作用-天线蛋白5个通路均发生变化，说明光合系统是CuO-NPs的主要攻击靶点；藻细胞通过调控过氧化物酶体、抗坏血酸代谢、谷胱甘肽代谢和ABC转运体通路来提高抵御CuO-NPs的能力。.MNPs 在水环境中归趋：微藻促进了离子的溶出，pH、Ca2+、HCO3-、HPO42-和黄腐酸（SRFA）通过影响CuO-NPs的离子释放、团聚和沉降，进而影响CuO-NPs在含藻水体-微藻胞外-微藻胞内三相中的分配及生物可利用性。微宇宙模型中底泥是纳米银主要汇集地。pH和温度为影响吸附的主要因素，藻对MNPs的吸附是一个单层覆盖和多层吸附共存，以化学吸附为主的自发性吸热过程。.本研究结果将为理解MNPs的环境归趋及生态效应提供重要的理论基础，也可为水环境中MNPs污染的生物修复提供科学依据。