污染河道反硝化型甲烷厌氧氧化及其影响因素研究

The accumulation of excessive carbon and nitrogen elements beyond the metabolic capacity of the river ecosystem is the origin of river pollution. Denitrification anaerobic methane oxidation (DAMO) is an ideal way to realize the coupling removal of carbon and nitrogen. Specific denitrifying bacteria and denitrifying archaea are the key of the carbon and nitrogen transformation, and the abiotic environmental factors play an important regulating role. To date, there is still a lack of systematic study on the mechanism of the relevant conversion process in polluted rivers..Based on the above issue, the present project focuses on the DAMO coupling nitrogen removal process in the sediment in polluted rivers. The in situ environmental genome analysis and simulation of indoor membrane reactor system are to be combined for elucidation of the composition, community structure, and the evolution of DAMO bacteria and archaea species. Based on the analysis of environmental genomics and carbon stable isotope fractionation, the changes of microbial composition and community structure, the dynamics of substrate conversion and the fate of methane and nitrogen species in the coupling removal process will be studied. The simulation system of the coupled carbon nitrogen removal reaction chamber of river sediment will be constructed, which allows to adjust the main environmental factors, for revealing the effect of microhabitat heterogeneity on carbon nitrogen removal efficiencies. The driving mechanisms of carbon nitrogen removal by the DAMO coupling process will be investigated from both microbial and chemical aspects..This research will innovate from theoretical and technological aspects. A novel research frame will be established for the driving mechanisms study on the DAMO coupling process of polluted rivers, which is comprised of the genome characteristics analysis of bacteria and archaea, coupled carbon and nitrogen transformation dynamic, spatial patterns, microhabitat heterogeneity of environmental factors aiming for the comprehensive control of river pollution. Combined with our own patented technology for the in situ sampling of surface sediment, an indoor simulation system of DAMO coupled reaction will be constructed, to carry out the study on the mechanism of stable isotope fractionation and the effect of microhabitat factors on carbon and nitrogen removal. The flow path of the simulation device and operation parameters will be optimized to accomplish a complete set of experimental simulation system with stabilized process.

污染河道汇聚过量碳氮元素，超过河流生态系统自身代谢能力，是造成污染的根源。反硝化型甲烷厌氧氧化是碳氮元素耦合转化，实现污染去除的理想路径。其中，反硝化型甲烷厌氧氧化细菌与古菌是元素转化核心，非生物环境因子起到调节作用，目前相关转化过程机理在污染河道中上尚缺少系统性研究。本研究针对上述问题，结合自有的沉积物原位采样专利技术，开发污染河道反硝化型甲烷厌氧氧化反应模拟系统，优化装置工作流程与工艺参数，构建基于分子生物学、稳定同位素技术、环境因子调控的综合研究技术体系，探明反硝化型甲烷厌氧氧化菌在污染河道中的分布特征、作用强度、时空分布规律及其在河流生态系统碳氮循环、温室气体排放与氮素污染修复中的作用，评估反硝化型甲烷厌氧氧化过程对典型生境因子的响应及其生态环境效应。增进对河流生态系统碳氮生物地球化学循环的认知，提供污染河道温室气体排放与氮素污染修复的新思路，为河道氮素污染控制提供科学支撑。

反硝化型甲烷厌氧氧化是近年来发现的，能够实现同步脱氮除碳的碳氮耦合转化过程，相关微生物过程在污染河道中能够缓解生活源污染输入导致的高营养负荷。以无锡市滨湖城市河道为例，选取了若干条典型城市河浜，通过原位调查、室内培养、模拟实验，采用高分辨率被动采样技术、分子生物学技术等技术，研究了污染河道DAMO微生物的群落结构和丰度的空间异质性特征，建立了DAMO微生物的富集培养体系，阐明了影响DAMO过程的关键环境因子，探讨了高营养负荷入湖河流对湖泊富营养化的潜在作用。.（1）阐明了城市河道DAMO微生物群落结构和丰度的空间异质性。研究发现，城市河道DAMO微生物的相对丰度整体较低，由于河道生境的异质性导致沉积物的微生物群落结构和DAMO微生物丰度具有显著差异，整体而言DAMO古菌的丰度要高于DAMO细菌。.（2）揭示了影响DAMO过程的关键控制因子。研究发现，研究发现，城市河道的理化性质和物质组成异质性对DAMO微生物有显著影响，相较于DAMO古菌，强还原、甲烷充足的环境更有利于DAMO细菌的生长，反应底物对DAMO古菌的限制不明显，而水体较高的pH值有利于DAMO古菌的生长。.（3）建立了DAMO微生物的富集培养体系。经过两年半的富集培养，探索出适合DAMO细菌富集的反应条件，反应器内相对丰度最高达到39.62%，绝对丰度最高达到3.47*108 Copies g-1沉积物，脱氮速率最高达到72.77 mg L-1 d-1，甲烷氧化速率最高达到211.2 mmol d-1。.（4）研究了城市河道温室气体释放潜力和排放通量特征。研究结果发现，典型城市污染河道温室气体排放时空异质性明显，N2O排放通量呈现冬春季高、夏秋季低的特征，CH4排放通量呈现夏季高、秋冬季低的特征。不同河道的甲烷释放潜力具有显著差异，高有机质负荷的沉积物有利于甲烷的释放。