【作者】 宋睿；

【导师】 王晓蓉； 高士祥；

【作者基本信息】 南京大学 ， 环境科学， 2011， 硕士

【摘要】 我国是世界上蓝藻水华暴发最严重、分布最广泛,并且水华的蓝藻种类最多的国家之一。蓝藻水华的暴发不仅改变了环境因子(水体出现低溶解氧、高pH、高化学需氧量等特征),还分解产生了大量的衍生物质,包括微囊藻毒素、铵态氮、硝态氮、硫化氢、嗅味物质(硫醚类物质、2-甲基异莰醇等物质),严重影响了水质和水生生态系统结构与功能,甚至危害了水生生物和人类的健康。铵态氮是典型的蓝藻水华衍生物质。本文重点研究蓝藻水华衍生物铵态氮对典型沉水植物苦草和重要淡水鱼类日本锦鲫的生物效应；本文还研究了铵态氮与典型重金属Cd的联合作用对日本锦鲫的生物效应,以及铵态氮与典型蓝藻水华衍生物微囊藻毒素MC_LR的联合作用对鲤鱼的生物效应,以期探明蓝藻水华暴发对水生生态系统的致毒效应与机制。本研究将传统毒理学研究方法与分子生物学技术相结合,以期寻找到蓝藻水华暴发条件下沉水植物和鱼类生存的铵态氮安全浓度,为我国蓝藻水华成灾的生态安全阈值指标体系,以及蓝藻水华消亡过程中适合不同功能区的水质安全指标体系的建立提供科学依据。本文的主要研究结果归纳如下：1.苦草对铵态氮暴露最敏感的生理生化指标是叶片中游离氨基酸态氮含量。铵态氮浓度低于0.60mg/L时苦草生长良好,浓度大于或等于1.00mg/L时苦草的光合能力受到抑制、代谢受到干扰。铵态氮作为沉水植物的一种营养物质,当其含量较低时,植物由于营养缺乏诱导产生自由基。2.日本锦鲫对铵态氮暴露敏感的生理生化指标是抗氧化酶SOD、CAT活性以及MDA含量。铵态氮浓度达到0.50mg/L(非离子氨NH3浓度为0.008 mg/L)时诱导日本锦鲫肝脏产生氧化应激。铵态氮浓度达到5.00mg/L(非离子氨NH3浓度为0.086 mg/L)时诱导日本锦鲫肝脏产生氧化应激,并出现氧化损伤和蛋白损伤。3.日本锦鲫对重金属Cd暴露敏感的生理生化指标是抗氧化酶SOD活性。Cd浓度为0.005 mg/L、铵态氮浓度为0.50 mg/L(非离子氨NH3浓度为0.006mg/L),其联合作用诱导日本锦鲫肝脏产生氧化应激,并且铵态氮的存在加剧了重金属Cd对日本锦鲫的氧化胁迫。Cd浓度为0.005 mg/L、铵态氮浓度为1.00mg/L(非离子氨NH3浓度为0.013 mg/L),其联合作用诱导日本锦鲫肝脏出现氧化损伤。4.微囊藻毒素MC_LR浓度为1.0pg/L、铵态氮浓度为10.0mg/L(非离子氨浓度为0.006 mg/L)以及其联合作用诱导了鲤鱼肝脏产生氧化应激。实验结果并未表明MC_LR浓度为1.0pg/L)和铵态氮(浓度为10.0mg/L)的联合作用比单一作用对鱼类的毒性更大。综上,在蓝藻水华暴发水体pH值较高的条件下,铵态氮浓度超过0.50mg/L即会对沉水植物和鱼类产生影响；并且铵态氮的存在加剧了重金属Cd对鱼类的胁迫。本实验结果表明微囊藻毒素MC_LR和铵态氮的联合作用并未比单一作用对鱼类产生更明显的胁迫。更多还原

【Abstract】 China was one of the countries which had the most serious eruption of cyanobacteria blooms that widely distributed and the most species of cyano-bacteria. The eruption of cyanobacteria blooms not only changed the envi-ronmental factors(low dissolved oxygen, high pH, high chemical oxygen de-mand, et al.), but also produced a large number of derivatives, including mi-crocystin, ammonia, nitrate, hydrogen sulfide and odor substances (sulfoether, 2- methyl isobutyl alcohol camphene, et al.). It seriously affected the water quality and the structure and function of the aquatic ecosystem, and even did harm to the aquatic organisms and human beings. This study focused on cyanobacterial blooms-producing ammonia and the biologic effects on typical aquatic organisms, submersed macrophyte Vallisneria natans L. and fresh-water fish Carassius auratus, and the combined effects of ammonia and Cd on Carassius auratus and the combined effects of ammonia and MC_LR on Cy-prinus carpio L. In an attempt to obtain the data of toxicity and mechanism of eruption of cyanobacteria blooms, the traditional toxicology methods were used, which were combined with molecular biology. This study provided a scientific basis for the system of ecological security threshold on the outbreak of cyanobacterial blooms, and the standards for water safety in different func-tional areas during the process of cyanobacterial blooms diminishing. The major results were summarized as follows:1. Among all those physiological parameters measured, the nitrogen contents in the free amino acids of the plant leaves was the most sensitive indicator. Submersed macrophyte Vallisneria natans L. grew well when the NH4+-N concentration was below 0.60mg/L and stress and growth disturbance happened when it was above 1.00mg/L Results also suggested that defi-ciency of nutrient at a low level of ammonia may cause the induction of free radicals in submerged plant leaves.2. Among all those physiological parameters measured, the activity of SOD and CAT and the contents of MDA in the liver proved to be the most sensitive indicators.NH4+-N induced oxidative stress of the liver in Carassius auratus at concentration of 0.50mg/L(NH3-N 0.008mg/L), and induced oxida-tive damage and protein damage at concentration of 5.00mg/L(NH3-N 0.086 mg/L).3. Among all those physiological parameters measured, the activity of SOD in the liver proved to be the most sensitive indicator to Cd exposure. Oxidative stress of the liver in Carassius auratus was induced at concentration of 0.005 mg/L Cd and 0.50mg/L NH4+-N(NH3-N 0.006mg/L). Oxidative damage of the liver in Carassius auratus was induced at concentration of 0.005 mg/L Cd and 1.00mg/L NH4+-N(NH3-N 0.013mg/L).4. Oxidative stress of the liver in Cyprinus carpio L. was induced at concentration of 1.0μg/L MC_LR,10.0mg/L NH4+-N(NH3-N 0.006mg/L)and combined effect of MC_LR and NH4+-N. The results did not show that the combined effects of MC_LR and ammonia more toxic than a single one.In summary, NH4+-N would have an effect upon aquatic plants and fish when its concentration were in excess of 0.50mg/L The combined effects of Cd and ammonia were more toxic than the single effects of Cd. The combined effects of MC_LR and ammonia were not more toxic than a single one.更多还原