养殖废水人工湿地处理系统中厌氧氨氧化菌的时空变化规律与功能效应研究

Anaerobic ammonium oxidation (anammox) has become a research highlight in the fields of biological denitrification and nitrogen (N) cycle, due to it can directly change ammonia nitrogen to nitrogen gas and avoids the generation of greenhouse gas - nitrous oxide (N2O). Presently, constructed wetlands (CWs) is increasingly used to lower the N load from agricultural nonpoint sources. Microbial action are the main mechanism of N transformation in CWs, however, the dynamic change and functional roles of anammox bacteria in CWs are still unknown and should in-depthanalysis and assessment. A CWs system treating rural swine wastewater will be selected as the research object in this work and research methods, including real-time quantitative PCR, high-throughout sequencing and isotope tracer technique, will be carried out to explore the spatiotemporal variation of anammox bacterial abundance, diversity and activity in the sediments of CWs. Moreover, the influence of soil environmental factors, plant and other N transforming microbes on anammox bacteria will be analyzed by statistical methods. Meanwhile, continuous flow analyzer method and static chamber-gas chromatograph technique will be carried out to routinely monitoring the N removal and N2O emission flux characteristics. Finally, the effects of anammox bacteria in N removal and N2O emission reduction will be assessed by integrated with its dynamic change and N transforming rates. Through the work all above, this research will help to improve the knowledge of microbial N removal mechanism in CWs, and also provide theoretical basis for reasonably regulating the microbial N transformation process and the reduction of N2O emission in CWs.

厌氧氨氧化可将氨氮直接转化为氮气且避免了温室气体N2O的产生而成为生物脱氮和氮循环领域的研究亮点。当前人工湿地技术在农业面源氮素污染源头治理中应用广泛。微生物作用是人工湿地氮去除的主要机制，但关于湿地中驱动厌氧氨氧化的微生物的动态变化与功能效应仍不清楚，亟待深入解析与定量评估。本项目拟以处理农村养殖废水的人工湿地系统为研究对象，采用荧光定量PCR、高通量测序和同位素示踪等技术全面揭示湿地土壤厌氧氨氧化菌的丰度、多样性和活性的时空变化规律，并综合运用统计分析方法阐明土壤环境因子、植物和其它氮转化微生物对其变化的影响；采用连续流动分析仪和静态箱-气相色谱法系统监测湿地氮去除和N2O排放特征，进而结合厌氧氨氧化菌的动态变化及氮转化速率评估其对湿地氮去除与N2O减排的效应。本研究有助于提高人工湿地微生物脱氮机制的认识，可为调控湿地微生物氮转化过程和N2O减排提供理论基础。

厌氧氨氧化因可直接将氨氮转化为N2且避免了温室气体N2O的产生而成为废水生物脱氮和氮循环领域的研究亮点。当前，人工湿地技术在农业面源氮素污染源头治理中应用广泛，但有关厌氧氨氧化在人工湿地处理中的作用及机制尚不清楚。本项目以典型的农村养殖废水多级人工湿地处理系统为对象，采用荧光定量PCR、克隆文库和15N-稳定同位素示踪等技术研究了人工湿地中厌氧氨氧化细菌的存在与丰度、群落组成与多样性、活性与脱氮贡献、以及关键环境影响因子。厌氧氨氧化细菌在不同强度养殖废水的人工湿地处理野外中试系统的底泥中广泛存在和分布，其功能基因hzsB丰度为0.75–3.46 × 106 copies g-1，活性大小为1.03–12.5 nmol N g-1 h-1，构成其群落的主要属为 “Ca. Brocadia”和“Ca. Kuenenia”，占至55.7%。底泥NH4+-N, NO2--N 和pH是影响厌氧氨氧化细菌丰度和活性的显著环境因子。粗略估算通过厌氧氨氧化作用去除的氮量为0.83–2.68 kg N yr-1，约占人工湿地总氮去除量的10%左右，表明厌氧氨氧化作用是人工湿地处理中一个不可忽视的氮去除途径。本项目研究结果有力证实了厌氧氨氧化过程在处理农村养殖废水的人工生态湿地系统中存在并发挥氮去除作用，为提升人工湿地处理系统中氮去除机制的认识和氮通量计算的科学性奠定了科学依据，对于人工湿地技术更好地在农业氮污染治理中推广具有重要的理论研究价值。