南极苔原环境厌氧氨氧化过程及其调控机理研究

The discovery about the process of anaerobic ammonium oxidation（Anammox）is a breakthrough in the field of environmental sciences in recent years. Anammox has been confirmed to widely exist in the anaerobic environment of the nature, and it plays an important role in the nitrogen cycle processes, but there is no report about Anammox in the Antarctic environment. In this project, tundra wetlands on Fildes Peninsula of maritime Antarctica are selected to be as study areas, and the molecular biology technology, microbiology and biogeochemistry methods are used to study community structure of Anammox bacteria and their spatial distribution patterns in the environment of Antarctic tundra, to study the spatial variations of Anammox rates and their influencing factors, to find out the key regulatory factors influencing the process about Anammox in Antarctic tundra environment and its mechanism, to discuss the contribution rate of Anammox to nitrogen loss, to evaluate the intensity of Anammox in tundra environment, and its importance in the nitrogen transformation, to explore the potential coupling relationships between Anammox-denitrification-dissimilatory nitrate reduction to ammonium (DNRA). The results of this project will reveal the effect of Anammox process, environmental regulatory mechanism and its role in the tundra nitrogen cycles under the extreme environmental conditions in Antarctica, and will provide the theory evidence to accurately describe the nitrogen cycle in the Antarctic tundra, and will further promote the understanding of the process and mechanism of nitrogen cycle in Antarctica.

厌氧氨氧化（ANAMMOX）过程的发现是近年来环境科学领域的重大突破，已证实该过程普遍存在于自然界厌氧环境中，并对氮循环过程起重要作用，但目前还未见有文献报道南极环境中存在厌氧氨氧化。本项目以南极法尔兹半岛苔原湿地作为研究区域，应用分子生物学技术、微生物学和生物地球化学方法等，研究南极苔原环境中厌氧氨氧化细菌群落结构与空间分布规律，研究厌氧氨氧化速率的空间变化规律及其影响因素，查明影响南极苔原环境厌氧氨氧化过程的关键调控因子及其作用机理；探讨厌氧氨氧化过程对氮气损失的贡献率，评估苔原环境厌氧氨氧化强度及其在氮转化中的重要性；探索厌氧氨氧化-反硝化-硝化-硝酸盐异化还原成铵（DNRA）之间潜在的耦合作用关系。通过本课题的研究，将揭示南极极端环境下厌氧氨氧化过程效应、环境调控机理及其在苔原氮循环中的作用，为精确描述南极苔原氮循环过程提供理论依据，推进人们对南极氮循环过程和机制的认识。

厌氧氨氧化（Anammox）普遍存在于自然界厌氧环境中，对氮循环过程起重要作用，但目前还未见有文献报道南极环境中存在厌氧氨氧化。本项目应用了氮稳定同位素示踪和分子生物学方法，研究了南北极苔原土壤、湖泊与近海沉积物中厌氧氨氧化等氮转化速率的空间变化规律，以及相关的功能微生物群落多样性变化特征、调控因素及其对苔原和湖泊氮循环过程的影响。发现南极苔原土壤存在厌氧氨氧化菌（AnAOB），阐明了苔原土壤厌氧氨氧化菌基因丰度及其群落的组成；企鹅粪土中AnAOB共有4属5种，以Kuenenia属数量最多；AnAOB基因丰度受pH值影响显著，而厌氧氨氧化速率受控于氨氮水平和碳氮比；Anammox对土壤脱氮贡献率与企鹅或海豹活动影响下的土壤碳氮比和硝氮/氨氮比显著相关。查明了南极苔原土壤氨氧化速率、氨氧化细菌（AOB）与古菌（AOA）群落多样性空间变化特征，发现AOB和AOA活性、丰度及其群落组成与企鹅或海豹活动导致的土壤碳氮比改变有关。阐明了南极湖泊沉积物氮转化速率及其相关微生物群落多样性特征，发现沉积物中存在Brocadia属AnAOB，且其菌群结构受pH和硝态氮含量的调控；查明沉积物AnAOB基因丰度与nirS和AOB amoA基因丰度呈显著正相关；Anammox与硝酸盐异化还原成铵（DNRA）相耦合导致了沉积物更高的脱氮贡献率，在湖泊氮循环中发挥了重要作用。查明了北极王湾沉积物厌氧氨氧化与其它氮转化的速率及其菌群组成，沉积物AnAOB均为Scalindua属，且Anammox对沉积物脱氮作用的贡献率较高；探明了新奥尔松苔原断面土壤N2O产生，可能主要由硝化作用有关的微生物驱动。还开展了南极苔原微生物群落多样性变化特征，以及多环境变量对南北极苔原温室气体源汇通量的影响研究；查明了南极苔原土壤微生物群落多样性空间变化特征；阐明了紫外辐射强度、光照、温湿度和冻融作用等对苔原温室气体通量与产生过程的综合影响等。.发表标有该项目资助号的国内外核心期刊论文计14篇。通过该项目，为我国在南北极积累了大量的氮转化速率及其功能微生物群落丰度和组成、温室气体浓度与通量等的资料，为精确描述南极苔原氮循环过程提供了理论依据，推升了人们对南北极环境氮循环过程和机制的认识。