Peatlands are an important source of nitrous oxide (N₂O) emissions, which is a potent greenhouse gas and is also involved in the depletion of stratospheric ozone. Due to the large number of N₂O production and consumption processes, it is challenging to trace N₂O emissions to an individual process. We investigated the effect of different water regimes (dry, intermediate and flooded) on N₂O emissions via ¹⁵N tracing in a microcosm study with well-decomposed nitrogen-rich alluvial fen peat. The isotopic composition of the peat and emitted N₂O gas was analysed in combination with qPCR analysis of abundances and diversity of N-cycle functional genes. Bacterial denitrification was the predominant source of N₂O emission, followed by nitrification (ammonia oxidation). This was identified by a close relationship between ¹⁵N-N₂O and ¹⁵N-NO₃⁻ under flooded (anoxic) and intermediate (sub-oxic) treatments and concomitant increases in nirK, nirS and nosZ after the flooding. The site preference and δ¹⁸O values fell within the previously observed range indicating multiple overlapping processes and bacterial denitrification as the dominant process. Although the combination of isotopic and microbial analyses indicates that bacterial denitrification is the primary process under intermediate and flooded treatments, the high abundance of amoA indicates that nitrification via comammox was present. High archaeal amoA and bacterial amoA gene copy numbers and second highest N₂O emissions under the intermediate and flooded peats indicated that ammonia oxidation was, secondary to denitrification, also a source for N₂O. The increase in emissions with nrfA gene copies also showed that dissimilatory nitrate reduction to ammonium (DNRA) potentially contributed to N₂O emission under flooded treatment.

泥炭地是一氧化二氮 (N ₂ O) 排放的重要来源，它是一种强效温室气体，也与平流层臭氧的消耗有关。由于 N _{2 O 生产和消耗过程数量众多，因此很难将 N 2} O 排放追踪到单个过程。^{我们通过15} N 追踪研究了不同水体（干水、中间水和淹水）对 N ₂ O 排放的影响，该研究对分解良好的富氮冲积泥炭进行了微观研究。泥炭的同位素组成和排放的 N ₂结合对 N 循环功能基因的丰度和多样性的 qPCR 分析分析 O 气体。细菌反硝化是 N ₂ O 排放的主要来源，其次是硝化作用（氨氧化）。这通过在淹水（缺氧）和中间（低氧）处理下¹⁵ N-N ₂ O 和¹⁵ N-NO ₃ ^{-之间的密切关系以及淹水后}nirK、nirS和nosZ的伴随增加来确定。地点偏好和 δ ¹⁸O 值落在先前观察到的范围内，表明多个重叠过程和细菌反硝化作为主要过程。虽然同位素和微生物分析的结合表明细菌反硝化是中间处理和淹水处理的主要过程，但 amoA 的高丰度表明存在通过 comammox 的硝化作用。高古细菌amoA和细菌amoA基因拷贝数以及中间和淹没泥炭下的第二高 N ₂ O 排放表明氨氧化是继反硝化之后的 N ₂ O 的来源。nrfA排放的增加基因拷贝还表明，异化硝酸盐还原为铵 (DNRA) 可能导致淹没处理下的 N ₂ O 排放。