Seasonal concentrations and influencing factors of airborne microbes in Lhasa of China

Abstract:

[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.

Key words:airborne microbe;filter membrane sampling;fluorescence microscopy;concentration characteristics;influencing factors