Fungi diversity in PM_2. 5 and PM₁ at the summit of Mt. Tai: abundance, size distribution, and seasonal variation

Abstract. Fungi are ubiquitous throughout the near-surface atmosphere, where they represent an important component of primary biological aerosol particles. This study combined internal transcribed spacer region sequencing and quantitative real-time polymerase chain reaction (qPCR) to investigate the ambient fungi in fine (PM_2. 5, 50 % cutoff aerodynamic diameter D_a50 =  2.5 µm, geometric standard deviation of collection efficiency σ_g =  1.2) and submicron (PM₁, D_a50 =  1 µm, σ_g =  1.2) particles at the summit of Mt. Tai located in the North China Plain, China. Fungal abundance values were 9.4  ×  10⁴ and 1.3  ×  10⁵ copies m⁻³ in PM_2. 5 and PM₁, respectively. Most of the fungal sequences were from Ascomycota and Basidiomycota, which are known to actively discharge spores into the atmosphere. The fungal community showed a significant seasonal shift across different size fractions according to Metastats analysis and the Kruskal–Wallis rank sum test. The abundance of Glomerella and Zasmidium increased in larger particles in autumn, whereas Penicillium, Bullera, and Phaeosphaeria increased in smaller particles in winter. Environmental factors, namely Ca²⁺, humidity, and temperature, were found to be crucial for the seasonal variation in the fungal community. This study might serve as an important reference for fungal contribution to primary biological aerosol particles.