【作者】 陈莉；

【导师】 梁文艳；

【作者基本信息】 北京林业大学 ， 环境科学， 2010， 硕士

【摘要】 藻类及其次生代谢产物微囊藻毒素(MCs)的污染使人类的饮用水安全遭受严重威胁。作为一种杀藻降解藻毒素的新技术,电催化氧化法以其操作简便、与环境兼容等优点被众多学者研究,但是对于该方法处理过程的安全性却很少有学者关注。本文确立了发光菌法、脱氢酶活性法、蚕豆根尖微核法以及单细胞凝胶电泳法的实验条件,从急性毒性和遗传毒性两个方面对电催化氧化杀藻降解藻毒素过程中水样毒性的变化进行研究；结合处理过程中中间产物分析及水样性质检测,对该方法的安全性进行论述,提出方法运行过程中控制水质毒性的对策；并探讨了胞内物质及反应过程中生成的氧化性副产物对水质毒性的影响。研究结果表明：脱氢酶活性法以天然地表水作为菌种来源,转接培养1次后菌活性较好；样品液与菌液最佳混合比例为6：1；测试时混合液需在37℃恒温培养箱中激活50min以上。蚕豆根尖解离的最佳时长为50-60min,细胞染色时间应在30min以上。单细胞凝胶电泳实验中,细胞裂解180min、解旋30min后,于电压28V、电流300mA的条件下电泳55min可取得好的实验效果。电催化氧化法可有效去除水样中的藻毒素,初始浓度102μg／L的水样,处理30min后可使MCLR去除率达到100%；此外色素等其它胞内有机物也能被有效降解。电催化氧化法还可有效使藻细胞灭活,处理过程中藻毒素及其它各种胞内物质在藻细胞死亡的过程中被逐步释放出来,致使溶液中始终含有微量的MCLR。电催化氧化杀藻降解藻毒素的过程中水样会生成一些具有急性毒性的物质,使溶液的发光菌和脱氢酶毒性略有上升,但随着处理时间的延长,这部分物质会被氧化降解,最终出水基本不具急性毒性。未处理粗毒素水样蚕豆根尖微核率可达6‰～7‰,纯毒素水样则超过8‰。66.2μg／L以上浓度的粗毒素即可诱发小鼠细胞DNA损伤。随着处理的进行,细胞DNA损伤减小,水样的遗传毒性显著降低(P<0.05)。藻毒素降解的中间产物研究显示,反应生成的中间产物主要为小分子有机酸,随着处理时间的延长可完全去除。水样处理过程中应在MCLR完全降解之后适当延长处理时间,以提高方法的安全性。更多还原

【Abstract】 The pollution of algae and its secondary metabolites microcystins (MCs) are serious threats to drinking water security. As a new technology of killing algae and degrading microcystins, electrocatalytic oxidation catches great attention because of its simple manipulation and advantages of environmental compatibility. But few scholars are concerned about the security of treatment process.The experimental conditions of the luminescent bacteria acute toxicity test, dehydrogenase toxicity assay, Vicia faba root tip micronucleus method and single-cell gel electrophoresis assay were determined in this thesis. Based on acute toxicity and genotoxicity of the water samples, studies on the toxicity variation during the process of electrocatalytic oxidation killing algae and degrading microcystins were carried out. By combining analysis of intermediate products with water sample testing, the security of the method was discussed. In addition, the proposed method to control water quality toxicity during the process was offered. Furthermore the impact on water quality toxicity caused by intracellular material and oxidation by-product generated in the treatment was discussed.The results showed that for dehydrogenase activity method, using natural surface water as bacterial species sources and switch cultivating one time could make the activity of bacterial relatively good; the best ratio of sample fluid and bacteria was 6:1; before the testing, mixture was required to keep in a 37℃incubator for more than 50min to activating the bacterial. The best Vicia faba root dissociation time is 50-60min. The cell staining time should be more than 30min. During single-cell gel electrophoresis experiments, following 180 min cell lysis and 30min unwinding, electrophoresis for 55min in the electrical condition of 28V,300 mA can get good test results.Electrocatalytic oxidation can effectively remove microcystins in water samples. For water samples with a initial Microcystin-LR (MCLR) concentration of 102μg/L, the MCLR removal rate can reach 100% after 30min treatment. In addition, pigments and other intracellular organic matter can also be effectively degraded. Electrocatalytic oxidation can also effectively inactivate algal cells. During the treatment, microcystins and a variety of other intracellular substances were gradually released in the algal cell death process. As a result, there was a trace of MCLR in the water samples, persistently.During the process of electrocatalytic oxidation killing algae and degrading microcystins, some substances with acute toxicity were generated in water samples, causing the luminous bacteria and dehydrogenase toxicity of the solution to increase slightly. But along with the treatment, these substances were oxidized and degraded. As a result, the water samples ultimately showed little acute toxicity. The micronucleus rate of 45μg/L untreated crude MCLR was 6‰～7‰, while the rate of the same concentration of pure microcystins was more than 8‰. Over 66ug/Lμf crude MCLR can induce mouse cell DNA damage. As the treatment progressing, cells’DNA damage decreased, the genotoxicity of water samples showed a significantly decline (P<0.05).Studies on intermediate product of degrading microcystins showed that small molecule organic acids were the main intermediate reaction products and can be completely removed along with the processing time expending. During the water treatment process, appropriate extending treatment time can improve the security of this method after MCLR are completely degraded.更多还原