【作者】 李梅；

【导师】 朱利中；

【作者基本信息】 浙江大学 ， 环境科学， 2012， 博士

【摘要】 人工纳米颗粒已广泛应用在工业和生活各个领域,它们在生产、运输、使用及处理过程中不可避免地进入环境,从而对生态环境产生一定风险。本文研究了水中ZnO、TiO2.Al2O3和SiO2等典型氧化物纳米颗粒对大肠杆菌的毒性效应,探讨了水化学性质、共存纳米颗粒和表面活性剂对ZnO纳米颗粒(nano-ZnO)毒性的影响及机理。论文取得了以下主要结果：(1)初步探明了ZnO、TiO2、Al2O3和SiO：纳米颗粒对水中大肠杆菌的毒性效应和机理。超纯水中纳米颗粒对大肠杆菌的毒性大小为ZnO>TiO2(锐钛矿相)、Al2O3>SiO2、TiO2(金红石相)(无毒性)。Nano-ZnO的毒性主要来自其释放的锌离子；而锐钛矿相nano-TiO2和nano-Al2O3的毒性主要与颗粒自身和细菌间的化学或物理作用有关。(2)揭示了水化学性质对nano-ZnO大肠杆菌毒性的影响及其机理。不同培养基中Hano-ZnO毒性主要取决于游离Zn2+浓度和细菌对毒性的抵抗力,培养基成分和溶液渗透压分别影响游离Zn2+浓度和细菌的耐毒能力；磷酸根和有机物可显著降低游离Zn2+浓度,而等渗(0.85％NaCl、PBS)和富营养(MD、LB)条件可增强细菌耐毒能力,导致不同培养基中nano-ZnO毒性的差异。模拟天然水中nano-ZnO对大肠杆菌的毒性除由游离Zn2+浓度控制外,还受Ca2+、Mg2+的影响；pH、离子强度、阴离子和天然有机质(如胡敏酸和富里酸)均可影响nano-ZnO的溶解度以及游离Zn2+浓度,而Ca2+、Mg2+可与Zn2+竞争细胞的毒性位点,降低游离Zn2+毒性。(3)阐明了水中共存纳米颗粒和表面活性剂对nano-ZnO大肠杆菌毒性的影响及机理。未观察到nano-TiO2或nano-Al2O3对nano-ZnO毒性的影响。阴离子表面活性剂SDBS不仅可降低水中游离Zn2+浓度,还可降低水中Ca2+和Mg2+浓度,导致不同SDBS浓度时nano-ZnO毒性的差异。非离子表面活性剂Tween 80对nano-ZnO溶解和毒性影响不大。生物表面活性剂Saponins(皂角苷)可以与锌离子络合,从而降低nano-ZnO对大肠杆菌的毒性。更多还原

【Abstract】 Engineered nanoparticles have been widely applied in many areas of industry and life. They are increasingly released into the environment during their production, transportation, use and treatment, which may bring uncertain risk to the eco-environment. In this paper, the toxicities of oxide nanoparticles such as ZnO, TiO2, Al2O3, and SiO2 to Escherichia coli (E. coli) were investigated, and then the effects and underlying mechanisms of water chemistry, coexisting nanoparticles and surfactants on the toxicity of ZnO nanoparticles were discussed. The main results were as follows:(1) The toxicities and mechanisms of oxide nanoparticles such as ZnO, TiO2, Al2O3, and SiO2 to E. coli were explored. Nano-ZnO showed the highest toxicity, and then nano-TiO2 (anatase) and nano-Al2O3, and nano-SiO2 and nano-TiO2 (rutile) showed no toxicity. The toxicity of nano-ZnO was mainly from the released zinc ions, and the toxicity of nano-TiO2 and nano-Al2O3 was related to the chemical or physical interaction between nanoparticles and bacterial cells.(2) The influence mechanisms of water chemistry on the toxicity of nano-ZnO to E. coli were clarified. The toxicity of nano-ZnO in culture media showed that the toxicity mainly depended on the concentration of free zinc ions and the tolerant ability of bacteria to the toxicants. The PO43- and organic complexes in the media could decrease the concentration of free zinc ions, and the isotonic (0.85% NaCl, PBS) and rich nutrient conditions (MD, LB) could enhance the tolerance ability of bacteria to toxicants, which both mitigated the toxicity of nano-ZnO. The toxicity of water qualities of nano-ZnO to E. coli demonstrated that the toxicity of nano-ZnO depended on not only the concentration of free zinc ions but also the concentration of Ca2+ or Mg2+. The influence mechanism was different for various water qualities. Ionic strength, pH, anions, and natural organic matters such as humic acid and fulvic acid could influence the toxicities through effecting on the dissolution of nano-ZnO and the concentration of free zinc ions. Ca2+ or Mg2+ alleviated the toxicity via competing with Zn2+ for the toxic sites of cells. (3) The effects of coexisting nanoparticles and surfactants on the toxicity of nano-ZnO to E. coli were studied. Nano-TiO2 (anatase) or nano-Al2O3 had no influence on the toxicity of nano-ZnO. SDBS could reduce the concentration of free Zn2+, Ca2+, and Mg2+, which influenced the toxicity of nano-ZnO. Tween 80 had little influence on the dissolution and toxicity of nano-ZnO, and Saponins could complex with zinc ions, which decreased the bioavailability of zinc ions, and thus decreased the toxicity of nano-ZnO to E. coli.更多还原