微生物介导的黄河三角洲滨海湿地AOM途径及其影响机制研究

Anaerobic ammonia oxidation (AOM) process of wetlands was a potential scientific problem of global methane (CH4) sink, which was easy to ignore, to mitigate global warming due to CH4 emission, macro-genomics and stable isotope tracer method were adopted to investigated the AOM pathway of coastal wetland in the Yellow River delta, mainly including the following aspects: (1) the AOM potential of coastal wetland under different salt marsh vegetation communities and different soil layers were investigated to find the correlation between vegetation type, organic carbon, other factors and AOM potential, and reveal the main AOM pathway in different salt marsh vegetation communities by stable isotope tracer technique and laboratory culture experiments with different electron acceptors; (2) the main microbial community structure and abundance and functional genes which were related to AOM pathway were included by using modern molecular biological means such as high-throughput sequencing, establish the gene library of microbial feature function and reveal the microbial mechanism of AOM pathway in coastal wetland; (3) Basted on the study of the AOM pathway in coastal wetland, further explore its circulation patterns of CH4. This study is of great significance to mitigate the global warming caused by CH4 emission and provide scientific basis for the reduction of CH4 emission in coastal wetlands.

针对减缓因CH4排放而带来的全球气候变暖的实际需求，围绕湿地厌氧氨氧化（AOM）这一容易被忽视的潜在的全球CH4汇的科学问题，采用宏基因组学和稳定同位素示踪方法，以黄河三角洲滨海湿地为对象，重点研究：（1）不同盐沼植被群落下滨海湿地土壤不同土层的AOM潜力，探究滨海湿地植被类型、盐度、有机碳等因子与AOM潜力的相关性。同时应用稳定同位素示踪技术，通过添加不同电子受体的室内培养试验，揭示黄河三角洲滨海湿地不同盐沼植被群落下AOM的主要途径；（2）采用高通量测序等现代分子生物学手段，研究参与黄河三角洲滨海湿地AOM过程的主要微生物群落结构与丰度以及功能特征基因，建立微生物特征功能基因文库，揭示滨海湿地AOM过程的微生物机制；（3）在滨海湿地AOM途径研究的基础上，进一步探究滨海湿地CH4的循环模式。这对于减缓因CH4释放而带来的全球气候变暖具有重要意义，以期为滨海湿地CH4减排提供科学依据。

湿地厌氧氧化（AOM）是减少CH4释放到大气中的重要生物地球化学过程，是全球重要的但容易被忽视的潜在CH4汇，是全球气候变化研究的热点。AOM 途径主要分为反硝化型甲烷厌氧氧化(DAMO)、硫酸盐还原型甲烷厌氧氧化(SAMO)以及以Fe3+/Mn4+作为电子受体的AOM 途径。本项目从DAMO、SAMO以及以Fe3+、Mn4+作为电子受体对黄河三角洲滨海湿地AOM 过程进行深入系统研究。主要研究：（1）不同盐沼植被群落下滨海湿地土壤不同土层的AOM潜力，探究滨海湿地植被类型、盐度、有机碳等因子与AOM潜力的相关性。同时通过添加不同电子受体的室内培养试验，揭示黄河三角洲滨海湿地不同盐沼植被群落下AOM的主要途径；（2）采用高通量测序等现代分子生物学手段，研究参与黄河三角洲滨海湿地AOM过程的主要微生物群落结构与丰度以及功能特征基因，揭示滨海湿地AOM过程的微生物机制；（3）在滨海湿地AOM途径研究的基础上，进一步探究滨海湿地CH4的循环模式。研究结果表明：土壤植被、深度、pH、ORP、EC、TP、NO3-、SO42-是影响AOM的关键环境因子，该过程还与土壤的细菌多样性有关；在NO3-/NO2-、SO42-和Fe3+/Mn4+等多种电子受体共存的条件下，NO3-是驱动AOM过程的关键电子受体；微生物层面，湿地土壤细菌中有硝酸根还原能力的Paenibacillus以及古菌中的Candidatus_Methanoperedens是驱动滨海湿地AOM过程的关键功能微生物；并基于以上研究提出了CH4的循环模式。总体而言，AOM速率受多种环境因子和微生物因子影响，而以NO3-作为电子受体的DAMO过程可能是最关键的甲烷汇，但不同区域又存在着明显的差异。考虑到近年来渤海湾氮污染问题比较突出，未来DAMO过程在统筹控制我国陆海污染和全球气候变化方面的重要性将会更加突出，能为我国黄河流域高质量发展与生态保护及碳达峰、碳中和国家战略提供重要的技术支撑。