【背景】空气微生物是城市生态系统的重要组成部分，其浓度对于监测城市空气质量、治理环境污染、预防疾病发生具有重要意义。【目的】研究拉萨市空气微生物分布特征，探讨气象因素和空气颗粒物对空气微生物分布特征的影响。【方法】基于荧光显微镜法分析了2019年10月-2020年10月不同季节空气微生物浓度及附着特征，结合气象因素和环境指标分析其影响因素。【结果】在荧光显微镜下，经过SYBR Green I染色的微生物呈亮绿色，规则椭圆状，大小在0.5-1.0 μm之间，同时还观察到微生物附着在有机物和黑碳上的现象。拉萨市空气微生物浓度变化范围为3.10×103-2.38×104 cells/m3，冬季空气中2种存在形式的微生物(自由漂浮和附着颗粒物)浓度最高。自由漂浮微生物浓度在秋季最低，与冬季存在显著差异(P<0.05)，不同季节颗粒附着微生物的浓度差异不显著。Spearman相关性分析表明，微生物浓度与气象因素无显著相关，但与空气中颗粒物浓度呈显著正相关(P<0.05)。【结论】拉萨市空气微生物浓度与全国其他城市相比处于较低水平，而且受空气污染物的影响。
[Background] Airborne microbes are a key component of the urban ecosystem, the concentration of which has great significance for monitoring urban air quality, controlling environmental pollution, and preventing disease. [Objective] To analyze the distribution characteristics of airborne microbes in Lhasa of China and explore the effects of meteorological factors and air particulate matter on the distribution of airborne microbes. [Methods] The airborne microbes were stained by SYBR Green I and observed under an epifluorescence microscope. The seasonal concentrations of the microbes from October 2019 to October 2020 were determined. Furthermore, the correlations of the concentration of airborne microbes with meteorological factors and environmental indicators were studied. [Results] The airborne microbes appeared bright green, oval, with a diameter of 0.5-1.0 μm and attaching to the organic matter and black carbon. The concentrations of total microbes in Lhasa ranged from 3.10×103 to 2.38×104 cells/m3. The concentrations of airborne microbes in two forms (free-floating and particle-attached) were the highest in winter. The concentration of free-floating microbes was the lowest in autumn, which was significantly different from that in winter (P<0.05). The concentration of particle-attached microbes showed no significant difference among four seasons. Furthermore, the concentration of airborne microbes was not significantly correlated with meteorological factors, while it had a significant positive correlation with the concentration of air particulate matter (P<0.05). [Conclusion] The concentration of airborne microbes in Lhasa was at a low level compared with that in other cities and affected by air pollutants.