蓝藻胞外含氮有机物在水华生消过程中的变化规律研究

Cyanobacteria releases large amounts of nitrogenous organic matter into surface water during the outbreak and decline of algal bloom. This would seriously threat the water supply security, due to the unsatisfactory removal efficiency of low molecular weight and hydrophilic nitrogenous organic matter in conventional water treatment plants and the increase in nitrogenous disinfection by-products. This project takes qualitatively and quantitatively characterization of the cyanobacterial nitrogenous organic matter as key point, which would be mainly performed by size exclusion chromatography-organic carbon detection-organic nitrogen detection (LC-OCD-OND), three-dimensional excitation emission matrix fluorescence spectroscopy and infrared spectroscopy technique. The research works would concentrate on: (1) Establish and optimize the simultaneous detection method of the nitrogenous organic matter content and molecular weight distribution in algae-laden water. (2) Figure out the change law of the cyanobacterial nitrogenous organic matter during the outbreak and decline of the algal bloom, explore the release route of different molecular weight nitrogenous organic matter, and finally build the dynamics model. (3) Explore the effects of environmental stress on the algal cellular structure, cell membrane integrity, cellular antioxidant system and the nitrogenous organic matter metabolism, thus establishing the influence mechanism of environmental stress on the cyanobacterial nitrogenous organic matter excretion. This research would provide scientific basis for predicting the changes of algal nitrogenous organic matter during the breakout and decline of algal bloom and offering the theoretical guidance for water resource management and water supply safety.

蓝藻在水华生消过程中会向水体释放大量含氮有机物，而传统水处理工艺对小分子和亲水性含氮有机物的去除效果较差，造成水厂出水含氮消毒副产物含量增加，严重影响供水安全。本项目以水华蓝藻含氮有机物的定性定量表征为切入点，以凝胶色谱-有机碳-有机氮探测技术、三维荧光光谱技术和红外光谱技术等为主要手段，重点开展：（1）建立并优化高藻水中含氮有机物含量和分子量分布的同步定量分析方法；（2）探明水华爆发和消亡过程中蓝藻含氮有机物的变化规律，识别不同分子量含氮有机物的释放途径，建立动力学模型；（3）阐明环境胁迫对藻细胞结构、细胞膜完整性、胞内抗氧化系统和含氮有机物代谢等的影响，解析环境胁迫对含氮有机物释放的影响机制。以上研究将为预测水华爆发和消亡过程中藻源含氮有机物的变化规律提供科学依据，为地表水源管理和供水安全提供理论指导。

富营养化水体中过量繁殖的藻类会释放大量的含氮有机物，对给水处理和供水安全产生不可忽视的影响。本项目优化了基于液相色谱、紫外氧化、紫外检测器联用技术对高藻水中溶解性有机氮的含量和分子量分布的表征技术，对水华生消过程中典型蓝藻的胞外含氮有机物及其相应的生理特征进行了研究，结果表明：水华爆发条件下不同氮源（NO3-N、NH4-N）和氮磷比对蓝藻胞外含氮有机物特征影响不大，而藻种变化的影响较为显著；铜绿微囊藻在分层型水体不同水层中的垂向迁移可能引发补偿生长现象，且在补偿生长阶段更容易释放大分子和小分子含氮有机物，而铜胁迫后的补偿生长也会改变胞外有机物的分子量分布特征；氮胁迫或磷胁迫条件下铜绿微囊藻胞外含氮有机物的含量均增加，且随着胁迫程度的增大溶解性有机氮的释放量升高；水温下降时铜绿微囊藻胞内、外含氮有机物（如络氨酸类和色氨酸类蛋白质）均有所降低；过氧化氢胁迫下水华蓝藻拟柱胞藻较铜绿微囊藻更容易释放大分子和小分子含氮有机物；对蓝藻胞外含氮有机物和藻类生理参数进行主成分分析发现，大分子有机氮与细胞质膜电位、大分子生物聚合物呈正相关，而小分子有机氮与细胞膜完整性、超氧化物歧化酶呈正相关；EEM图谱和叶绿素a荧光参数有潜力作为指示藻源含氮有机物变化的在线监测手段。通过本项目的研究揭示了藻源含氮有机物在不同生境中的变化规律及影响机制，为蓝藻水华控制和饮用水安全供给提供了科学依据和理论指导。