随着城市化程度的提高以及气候变化和城市空气质量愈发重要，城市绿地土壤的氧化亚氮（N2O）和一氧化氮（NO）的排放受到越来越多的关注。本研究在北京市清华大学校园内的绿地上使用原位动态通量箱方法，进行了涵盖四个季度的长期观测，研究北京城市绿地裸露土壤及有植被覆盖的土壤N2O和NO排放通量及其主要影响因子。此外，还研究了氯化铵（NH4Cl）和硝酸钠（NaNO3）氮肥添加对土壤排放通量的影响。该站点的城市绿地N2O和NO的总年平均通量分别为8.73 kg N2O-N ha-1 yr-1和0.75 kg NO-N ha-1 yr-1，施氮样地的通量则分别上升为17.1 kg N2O-N ha-1 yr-1和11.1 kg NO-N ha-1 yr-1。未施氮的最高通量出现在夏季（28.5 kg N2O-N ha-1 yr-1 and 4.13 kg NO-N ha-1 yr-1）。降雨对于该样地的N2O和NO的排放通量影响极大，尤其是在长时间干燥之后的降雨。NH4Cl和NaNO3施肥实验开始后的三天内均产生极高的N2O排放，排放因子（EF）分别为2.89％和2.01％。这表明该城市绿地土壤中硝化反应和反硝化反应均为N2O的主要来源。与N2O不同，NH4Cl施肥后的EF非常高，为4.05％，而NaNO3对NO排放影响很小（EF = 0.053％）。这与以往研究结果相似，在干燥通气土壤中硝化反应是NO排放的主要过程。有无植被覆盖的土壤对降雨和氮肥施加后的响应差异表明，植被覆盖有利于土壤反硝化过程，无植被覆盖更有利于硝化过程。尽管有植被覆盖的土壤和裸露土壤地理位置彼此接近，但土壤性质和土壤微生物种群的差异仍可能导致这些差异。本研究表明城市绿地常规的管理，如施氮和浇水等，可能增加N2O和NO排放。这要求未来改变城市土地管理的政策，以减少城市温室气体的排放。

With increased urbanization coupled with concerns over climate change and urban air quality, fluxes of nitrous oxide (N2O), a greenhouse gas (GHG), and nitric oxide (NO), a major contributor to photochemical smog, from urban soils is of increasing concern. A year-long study on these flux trends from temperate urban lawn grass (Poa annua L.) and bare soil covers was conducted on the campus of Tsinghua University in Beijing city. An in situ dynamic chamber method was used. The contributions of temporal changes in urban environmental factors and of ammonium chloride (NH4Cl) and sodium nitrate (NaNO3) fertilizer additions to soil emission fluxes were measured. Mean N2O and NO fluxes without fertilizer treatment was 8.73 kg N2O-N ha-1 yr-1 and 0.75 kg NO-N ha-1 yr-1, respectively. Fluxes after fertilization raised means to 17.1 kg N2O-N ha-1 yr-1 and 11.1 kg NO-N ha-1 yr-1. The season with the highest mean fluxes without fertilizer was the summer (28.5 kg N2O-N ha-1 yr-1 and 4.13 kg NO-N ha-1 yr-1).Water saturation and soil temperature were major impacting factors for N2O flux. NO flux was strongly influenced by NO and NO2 ambient concentrations due to the decrease in diffusion gradient, especially in dryer seasons. Isolated rainfall events were important for both N2O and NO flux, especially after a long dry period. NH4Cl and NaNO3 additions both resulted in high N2O flux pulses, with comparable emission factors (EF) of 2.89% and 2.01%, respectively during the first three days following fertilization. This shows that N2O is emitted from both nitrifiers (either nitrifier denitrification or nitrification), and from denitrifiers (denitrification). NH4Cl was important for NO flux with a very high EF of 4.05% while NaNO3 did not influence NO emissions (EF = 0.053%), giving rise to the commonly share notion that nitrification is important for NO flux. Differences in the response of grass and bare cover types to rainfall events and fertilizer application indicate that grass plot type favors denitrification and bare favors nitrification. Differences in soil characteristics and microbe populations likely resulted in these differences despite their close proximities. This study reinforces the notion that common lawn practices such as N fertilization and irrigation are important for inducing N2O and NO flux. This calls for future policy changes in order to reduce urban GHG contributions.